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Existing earthquake damage reconnaissance reports indicate that many tunnels have suffered noticeable damage. During seismic excitation, ignoring the rock–concrete interaction may affect the accuracy of research results. In this study the influence of rock–concrete interaction on the response of a tunnel under seismic excitation was systemically investigated. A finite-difference method (FDM) model of the tunnel was constructed and full dynamic time history calculations were performed. The rock–tunnel interface was built using the FDM, with interface elements defined by a linear Coulomb shear strength criterion. The reliability of the numerical simulation of the interface was verified by comparisons with direct shear test results. Based on a real engineering case (Xianglushan water conveyance tunnel), two models with different rock–tunnel interactions were established and their seismic responses evaluated. The mechanical properties of the interface were compared. The seismic responses of the tunnel were assessed in terms of displacements, stresses and lining dynamic internal forces. The results indicated that rock–concrete interaction may have a significant effect on a tunnel's seismic response, and that effect has a certain pattern. The influences of the mechanical parameters of the interface on the seismic response of tunnels are complex and the stiffness of the interface plays a significant role. [ABSTRACT FROM AUTHOR]

Introduction: Previous medication adherence studies primarily focused on the domains of non-adherence in hypertension treatment and less attention has been given on domains that encourage adherence to anti-hypertensive medications. The current study is aimed to identify the domains of adherence and non-adherence to anti-hypertensive medications among hypertensive patients in Kuala Lumpur, Malaysia. Methods: Hypertensive patients from two public health clinics in Kuala Lumpur were invited for in-depth interviews until thematic saturation. Audio recordings from these interviews were transcribed verbatim. Transcripts were then analysed deductively with the guidance of the World Health Organization Medication Adherence Framework to extract the domains of adherence and non-adherence to anti-hypertensive medications. Results: Ten patients who were predominantly Malays and aged 34-73 years old participated the study. Patient-related (encompassing knowledge, attitude, belief and culture, lifestyle, personal barriers, self-efficacy, and cue to action), socioeconomic (encompassing social support), condition-related (encompassing nature of illness and presence of multiple co-morbidities), therapy-related (encompassing experience of receiving treatment, barrier in treatment, and side effects of treatment), and healthcare system (encompassing access to healthcare and healthcare center experience) domains were identified as central to the medication-taking behaviour of hypertensive patients. Conclusion: Sixteen codes of adherence and 22 codes of non-adherence to anti-hypertensive medications were identified, which were distributed across five domains (patient-related, socioeconomic, condition-related, therapy related, and healthcare system domains). These findings can help to inform future development of medication adherence questionnaires, individualised interventions for patients with adherence problems, and targeted health promotion programmes to reduce uncontrolled hypertension. [ABSTRACT FROM AUTHOR]

INTRODUCTION: No study has investigated the efficacy and safety of vonoprazan-amoxicillin dual therapy compared with bismuth quadruple therapy (B-quadruple). This study aimed to evaluate the efficacy and safety of 10-day vonoprazan-amoxicillin dual therapy as a first-line treatment of Helicobacter pylori infection compared with B-quadruple and to explore the optimal dosage of amoxicillin in the dual therapy. METHODS: A total of 375 treatment-naive, H. pylori-infected subjects were randomly assigned in a 1:1:1 ratio into 3 regimen groups including VHA-dual (vonoprazan 20 mg twice/day 1 amoxicillin 750 mg 4 times/day), VA-dual (vonoprazan 20 mg 1 amoxicillin 1,000 mg twice/day), and B-quadruple (esomeprazole 20 mg 1 bismuth 200 mg 1 amoxicillin 1,000 mg 1 clarithromycin 500 mg twice/day). Eradication rates, adverse events (AEs), and compliance were compared between 3 groups. RESULTS: The eradication rates of B-quadruple, VHA-dual, and VA-dual were 90.9%, 93.4%, and 85.1%, respectively, by per-protocol analysis; 89.4%, 92.7%, and 84.4%, respectively, by modified intentionto-treat analysis; 88.0%, 91.2%, and 82.4%, respectively, by intention-to-treat analysis. The efficacy of the VHA-dual group was not inferior to the B-quadruple group (P < 0.001), but VA-dual did not reach a noninferiority margin of 210%. The AEs rates of the B-quadruple group were significantly higher than those of the VHA-dual (P 5 0.012) and VA-dual (P 5 0.001) groups. There was no significant difference in medication compliance among 3 treatment groups (P 5 0.995). CONCLUSIONS: The 10-day VHA-dual therapy provided satisfactory eradication rates of >90%, lower AEs rates, and similar adherence compared with B-quadruple therapy as a first-line therapy for H. pylori infection. However, the efficacy of VA-dual therapy was not acceptable. [ABSTRACT FROM AUTHOR]

• Effect of nitrite on semi-continuous two-phase AD was firstly investigated. • The addition of nitrite promoted an increase in STOC and VFA contents. • The addition of nitrite increased VS reduction and had slightly impact on biogas production. • Microbial community changed significantly after addition of nitrite and Vulcanibacillus and Candidatus Methanofastidiosum become the dominant genera. • Nitrite pretreatment is relatively a cost effective alternative. Previous study found that the pre-treatment of sewage sludge with nitrite improves the biogas production during the mono/two-phase anaerobic digestion (AD) using batch biochemical methane potential tests. In this study, the effects of nitrite on hydrolysis-acidification, biogas production, volatile solids destruction and microbial composition in semi-continuous two-phase AD of sewage sludge were investigated. The addition of nitrite promotes sludge organic matter solubilization (+484%) and VFAs production (+98.9%), and causes an increase in the VS degradation rate during the AD process (+8.7%). The comparison of biogas production from the acidogenic and methanogenic reactors with or without the addition of nitrite implies that the nitrite has no significant effect on the overall biogas production of two-phase sludge AD process. High-throughput sequencing analysis shows that the microbial communities of bacteria and archaea in two-phase AD reactors significantly changes after the addition of nitrite. Vulcanibacillus (bacteria) and Candidatus Methanofastidiosum (archaea) become the dominant genera in the acidogenic and methanogenic reactors with the nitrite respectively. These findings provide new insights about using nitrite to promote the organic matter degradation of sewage sludge in a semi-continuous two-phase AD system. [Display omitted] [ABSTRACT FROM AUTHOR]

Due to the typical topography and hydrological characteristics in western Hubei's mountain and gorge areas, the landslide-surge-barrier dam disaster chain is the prevalent geological disasters. This research describes the blockage of Pingdu River by the Erhuang Village landslide (110°08′48″E, 31°47′27″N) that occurred in Shiyan, causing six deaths and serious damage of hydropower station. In order to reveal the mechanism of this disaster chain, it is critical to reproduce the complex fluid–solid coupling process involved in the disaster. The interaction between landslides and rivers, as the linking process in this disaster chain, basically determines the scale of secondary disasters. Therefore, we adopt the TPDP-MPM to establish the numerical model realistically: two sets of particles represent landslide and water body, respectively. Regarding the sliding surface as a computational boundary, we reproduced the landslide runout and river blockage process. By giving full advantages of TPDP-MPM, the chain generation mechanism of the strong coupling effect of soil–water in the landslide-surge-river blocking disaster chain is decoupled and analyzed from the energy perspective, a new understanding of the chain generation process is obtained, and the movement of landslide disaster chain was divided into three stages: acceleration and ejection, river braking, and accumulation. Besides, the chain generation mechanism and spatial–temporal evolution of the landslide-surge-barrier dam disaster chain, especially the mechanism of river-braking and the coverage of influence of surge, were discussed. This research provides a novel methodology for the reproduction and risk assessment of landslide-surge-barrier dam disaster chain. [ABSTRACT FROM AUTHOR]

In this study, three various types of rainfall with the measured rainfall events and data are used to analyze the stability of the high-fill deposit slope taking the influence of water deterioration into account. Under natural and saturated fully submerged conditions, the mechanical behaviors of the S-RM inside the slope are investigated, and the test results are taken into consideration in the numerical analyses as a reference to water deterioration. The test results show that the loss of the soil that filled in the spaces between the rock blocks due to the water migration has a clear negative impact on the shear strength and friction angle of S-RM. According to the simulation analyses, the negative pore water pressure (matric suction) exhibits a greater area of dissipation under the multi-peak type rainfall with the assistance of the antecedent rainfall, and the evident decrease in safety factor with the smallest value is also found with the upward movement of the potential sliding surface. When the water deterioration is taken into account, the deposit slope stability is more susceptible to rainwater infiltration, and the position of the potential sliding surface is more consistent with the matric suction dissipation. The results of this study support the notion that persistent antecedent rainfall and water deterioration are two key aspects in the stability of the high-fill deposit slope. [ABSTRACT FROM AUTHOR]

The mechanical properties of the rock-concrete contact surface are vital in the study of the ground-liner interaction for the tunnels embedded in rock mass. This paper mainly investigates the shear mechanical behaviour and failure mechanisms of the ground-tunnel interface with experimental and numerical approaches. Firstly, a Brazilian test was conducted to make a rough surface that represents the rock-concrete contact surface in the rock tunnelling. The split rough surface was then scanned with a 3 D scanning technique with which the digital terrain map (DTM) model of the split surface was acquired. In conjunction of the DTM model with a 3 D printing technique, synthetical samples that represent the rock-concrete contact surface were produced. These samples were put in shear test in which the shear behaviour and failure mechanism were investigated, and the shear strength criterion of the rock-concrete contact surface was presented. Ultimately, based on the discrete element method (DEM) code 3DEC, the numerical shear tests of the contact surface were performed. A sophisticated, nonlinear, continuously yielding (C-Y) model was adopted to describe the complex shear behaviour of the contact surface during the numerical shear test. The reasonable match of laboratory data with the numerical test results demonstrated the applicability of the DEM approach in reflecting the shear mechanical behaviour of the rock-concrete contact surface of liner. [ABSTRACT FROM AUTHOR]

Background: Tracheal stents can be placed in a narrow position in the human trachea to ensure smooth breathing. And the stent will deform during service by the influence of the physiological environment or random excitations, such as coughing. Methods: This paper divides the vibration into periodic and random vibrations according to the different pressures. And a coupling vibration model was established by analyzing the contact relationship between the stent and the trachea tissue. And this study discusses the influence of tracheal diameter, respiratory pressure, and frequency on the stent vibration characteristics through Ansys simulation. In addition, the nonlinear equations were solved by the Matlab numerical analysis method, which could help analyze the influence of cough intensity on the stability of the tracheal stent system. Results: The results showed that when tracheal stenosis occurred in the trachea's more significant grade, the trachea stent was more likely to fall off when treated with a tracheal stent. With the increase in respiratory frequency and pressure, the deformation of the tracheal stent is more considerable. Moreover, the frequency of normal cough hardly affects the stability of the stent system, while the excitation force and damping coefficient value greatly influence the system. When the excitation force of the cough exceeds the critical importance of 20 N, the tracheal stent is prone to fall off. This study comprehensively obtained the forced vibration characteristics of the stent under service conditions, which could make up for the shortage of the vibration theory of the stent. Conclusion: The results can provide a theoretical basis for predicting the possibility of stent loss in clinical treatment. [ABSTRACT FROM AUTHOR]

A reasonable prediction of the elastic modulus of rock and rock mass can provide sound basis for the design in tunnels and underground caverns. It is observed from the laboratory results that the elastic modulus not only depends on the confining pressure but also indicates certain sensitivity to the failure degree during the loading-fracturing process. This paper deduces a unified expression for the elastic modulus with the coupling effects of the plastic strain and confining stress, and fits the soft, moderate, hard rocks with different quality. In this paper, a method to determine the elastic modulus from the laboratory results is proposed. Through the method, the variation of the elastic modulus versus the plastic strain and confining stress for the soft, moderate, hard rocks is analysed. A unified deterioration model for the elastic modulus is developed by the nonlinear fitting regression method. This deterioration model can be employed in the analytical and numerical analysis of the tunnels and underground caverns, which enables to present a more realistic mechanical behaviour of rock mass. Highlights: Variation of elastic modulus versus plastic strain and confining stress for soft, moderate, hard rocks is analysed. A unified deterioration model for elastic modulus is developed by nonlinear fitting regression method. This deterioration model can be employed in analytical and numerical analysis of tunnels and underground caverns. [ABSTRACT FROM AUTHOR]

The regression analysis method is being widely adopted to analyse the tunnel strain, most of which ignore the strain-softening effect of the rock mass and fail to consider the influence of support pressure, initial stress state, and rock mass strength classification in one fitting equation. This study aims to overcome these deficiencies with a regression model used to estimate the tunnel strain. A group of geological strength indexes (GSI) are configured to quantify the input strength parameters and deformation moduli for the rock mass with a quality ranging from poor to excellent. A specific semi-analytical procedure is developed to calculate the tunnel strain around a circular opening, which is validated by comparison with those using existing methods. A nonlinear regression model is then established to analyse the obtained tunnel strain, combining twelve fitting equations to relate the tunnel strain and the factors including the support pressure, GSI, initial stress state, and critical softening parameter. Particularly, three equations are for the estimation of the critical tunnel strain, critical support pressure, and tunnel strain under elastic behaviour, respectively; and the other nine equations are for the tunnel strain with different strain-softening behaviours. The relative significance between the GSI, the initial stress and the support pressure on the tunnel strain is assessed. [ABSTRACT FROM AUTHOR]

Highlights: The dynamic behaviors of rock under different seismic loads are numerically simulated. The properties of rock under different seismic loads are analyzed and compared. The main factors of seismic load for the deformation properties of rock are determined. [ABSTRACT FROM AUTHOR]

Objectives: To explore the synergistic effect of vitamin D deficiency and sarcopenia on vertebral osteoporostic fracture (VF) in patients with rheumatoid arthritis (RA). Methods: A total of 188 patients with RA and 158 control subjects were enrolled. Bone mineral density (BMD) at the total hip, neck of femur, lumbar vertebra 1–4, and skeletal muscle mass was measured by dual energy X-ray absorptiometry (DXA) and biological electrical impedance, respectively. Serum 25(OH)D was tested by electrochemiluminescence. The prevalence of VF and osteoporosis (OP) were compared between RA and controls. The synergism of sarcopenia and vitamin D deficiency on VF in patients with RA was tested by χ2 test and logistic regression. Results: The prevalence of OP at all measured sites and VF in RA patients were all higher than those in controls (P < 0.0001). The incidence of VF in RA either with sarcopenia or with vitamin D deficiency was higher than for those without sarcopenia or without vitamin D deficiency (χ2 = 5.069, P = 0.027, χ2 = 8.822, P = 0.001). Age, disease duration, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), DAS28, health assessment questionnaire (HAQ), Sharp score, and body mass index (BMI) were significantly different between RA with sarcopenia or not (P < 0.05). Logistic regression analysis found that age (OR = 1.095, 95%, CI: 1.044–1.150, P < 0.0001) was a significant risk factor for VF in patients with RA, while high skeletal muscle mass (SMI) (OR = 0.513, 95% CI: 0.327–0.804, P = 0.004) was a protective factor for VF in RA patients. Conclusions: VF, sarcopenia, and vitamin D deficiency are common in patients with RA. Sarcopenia and vitamin D deficiency may be risk factors for the incidence of VF in RA patients. Key points: • RA patients had a higher incidence of OP and VF, also a high prevalence of sarcopenia and vitamin D deficiency. • Vitamin D deficiency and sarcopenia may might have a synergistic effect on VF in RA. • Aging and sarcopenia are risk factors for VF in RA patients, and sarcopenia were associated with disease activity and structural damage. [ABSTRACT FROM AUTHOR]

The bearing capacity of large strip foundations under combined loading is an important issue in geotechnical engineering, which is related to the design and stability analysis of foundations such as gravity dams, retaining walls, and ground anchorages of bridges. Herein, a new model for predicting the bearing capacity of large strip foundations under combined loading was proposed. First, a series of numerical simulation analyses of a large strip foundation resting on the surface of the soil were conducted to investigate the shape of the failure envelope in the V–M–H (vertical load, overturning moment, and horizontal load) loading space, and an improved form of failure equation was proposed. Second, the main factors influencing Vmax (the vertical ultimate bearing capacity) and the shape of the failure envelope were determined. Last, an applicable empirical equation of the failure envelope in the V–M–H loading space was presented. The results show that the deflection angle of the ellipse (θ), which is considered as a certain constant by previous studies, varies with the vertical load (V); the width of the foundation (B), the depth of the foundation (D), the cohesion of the soil (c), and the internal friction angle of the soil (φ) are the main factors influencing Vmax and the shape of the failure envelope; only parameters B, D, c, φ, and γ are needed to determine, in a unique way, the empirical equation of the failure envelope in the V–M–H loading space. The proposed model provides a convenient means of calculating the bearing capacity of large strip foundations on soil under combined loading. [ABSTRACT FROM AUTHOR]

Objective: To investigate the rate of subclinical inflammation in patients with axial spondyloarthritis (axSpA) with nonsteroidal anti-inflammatory drug (NSAID)/anti-tumor necrosis factor (TNF)-α drug-induced clinical remission and to explore factors influencing clinical and imaging remission. Methods: One hundred twenty-five patients with axSpA followed up for at least 6 months were enrolled in this prospective study and randomly divided into two groups. Ninety patients were treated with anti-tumor necrosis factor (TNF)-α or anti-TNF-α combined with nonsteroidal anti-inflammatory drugs (NSAIDs) (anti-TNF-α treatment group), and thirty-five patients were treated with only NSAIDs (non anti-TNF-α treatment group). The improvements in the clinical remission rate, imaging remission rate, and disease parameters before and after the different treatments were compared. Risk factors for clinical and imaging remission were analyzed by multivariate logistic regression analysis. Results: The clinical and imaging remission rate was increased after treatment especially in the anti-TNF-α group (P < 0.001). The remission rate of imaging in the group with clinical remission was higher than that in the group with clinical non-remission (P < 0.05). After treatment, the remission rates of imaging in the clinical remission and non-remission group were significantly higher than those before treatment (P < 0.0001). The results of multivariate logistic regression analysis showed that higher CRP was a risk factor for failure of clinical remission in axSpA (OR = 2.034, 95% CI:1.595 ~ 2.617, P < 0.001), while higher ASDAScrp was a risk factor for failure of imaging remission (OR = 1.306, 95% CI:1.026 ~ 1.688, P < 0.05). Anti-TNF-α treatment was a protective factor for both clinical (OR = 0.234, 95% CI:0.091 ~ 0.605, P < 0.05) and imaging remission (OR = 0.511, 95% CI:0.286 ~ 0.914, P < 0.05). Conclusion: Even after regular treatment, some clinical remission patients continued to have evidence of subclinical inflammation. Higher CRP and ASDAScrp are risk factors for clinical and imaging non-remission in axSpA respectively, Continuous NSAID treatment (more than 1 year) can effectively improve clinical and MRI inflammation in patients, but anti-TNF-α treatment is more beneficial for clinical and imaging remission. Key Points • Some patients achieving ASDAScrp remission status continue to have inflammation when assessed with objective imaging techniques. • MRI can sensitively measure bone marrow inflammation and may provide a more accurate assessment of remission. • Controlling inflammation, especially reducing CRP and ASDAScrp levels, is a key factor for achieving clinical and imaging remission in patients with axSpA. [ABSTRACT FROM AUTHOR]

Highlights: A dynamic constitutive model for rock materials suited to dynamic cyclic loading was established. The numerical tests on a hard rock under true triaxial dynamic cyclic loading with different loading rates were conducted. The dynamic deformation and mechanical properties of a hard rock were studied. [ABSTRACT FROM AUTHOR]

Due to topographical restrictions, transmission towers will inevitably be erected in areas prone to frequent geological disasters such as steep slope failure. Taking the Yanzi tower foundation landslide as the research object, the failure process of the tower foundation in a landslide and the corresponding failure mode under rainfall were studied through physical model testing and numerical theoretical analysis. Firstly, the planned design and testing process of the physical model test of the tower foundation landslide under rainfall were introduced. Secondly, the failure process of the tower foundation at different positions of landslide under rainfall was revealed. Then, the failure mode of the tower foundation landslide under rainfall was proposed. Finally, the failure mode of the tower foundation under rainfall was determined. According to the observed displacement of the tower foundation during a landslide in the model test, the instability of the toe of the landslide caused by scouring caused traction damage to the landslide. The tower foundations on the landslide and outside the trailing edge of the landslide became unstable and collapsed along with the landslide, while the tower foundation below the landslide remained stable. During the deformation stage of the landslide, there was no shear failure and no tipping damage to the tower foundation. If the potential landslide on which the tower foundation is located is unstable under heavy rainfall, the tower foundation may slide along with the potential landslide passing through the bottom of the tower foundation, which is consistent with the result of physical testing. [ABSTRACT FROM AUTHOR]

A two-stage analysis of the support-rock interaction is carried out using a proposed numerical procedure. The procedure provides a simplified solution for readily obtaining the final support load and rock mass displacement that is easier to use than the conventional Convergence-Confinement Method (CCM). The procedure accounts for the strain-softening behaviour of the rock mass and the effect of delayed support installation. Based on the procedure, a method to determine the delayed distance and allowable displacement for the support installation is presented. A Modified Ground Reaction Curve (MGRC) that relates the rock mass displacement to the final support load is introduced. The effects of the rock mass quality, initial stress, support type and strain-softening, dilatancy behaviours on the delayed distance and allowable displacement are investigated. A comparison between the predictions of the MGRC and GRC is conducted. The results indicate that the influence of the rock mass quality and initial stress on the support-rock interaction is more significant than that of the strain-softening and dilatancy behaviours. An approximate support design using the GRC may be acceptable for a weak rock mass, whereas the GRC results in an overly conservative support design for an excellent rock mass. [ABSTRACT FROM AUTHOR]

This paper presents a unified elasto‐plastic analysis of rock mass supported with fully ground bolts for deep tunnels. In the analysis, depending on whether the relative movement at the grout–bolt interface is considered, two finite‐difference algorithms are discussed. For each algorithm, two conditions, one when the rock bolt is inserted into the elastic area and one when it is included within the plastic area, are comprehensively investigated. In the algorithms, the initial and final states for the rock–bolt interaction are presented, and for each state, the surrounding rock mass consisting of the bolt or the plastic area is divided into a finite number of annuli through a constant radius increment. Based on this, the stress and displacement for the rock mass and the rock bolt are obtained step by step. The results of the two algorithms are verified by the analytical method and the field test data, respectively. Parametric studies were conducted to compare bolt force, rock displacement and stress components that are solved by the algorithms with and without considering relative movement. The proposed algorithms can be written into the software for guiding the rock bolt design in practical engineering. [ABSTRACT FROM AUTHOR]

Rock materials are often subjected to medium- and low-strain-rate dynamic cyclic loading such as earthquake action; however, few dynamic constitutive models for rock materials under dynamic cyclic loading are available. Therefore, it is important for evaluating the stability of rock engineering when analyzing the effects of seismic loading to establish a reasonable dynamic constitutive model for rock materials. This model can simulate the main characteristics of rock materials, such as the hysteresis loop, cumulative plastic deformation, strain rate effect, and damage effect. Thus, the formulation of a new dynamic constitutive model able to reproduce the cyclic behavior and dynamic mechanical properties of rock materials under dynamic cyclic loading is demonstrated and validated. First, by analyzing the variation of Young's modulus for different rock materials under static and dynamic cyclic loading, it is assumed that there exist strain rate effect and damage effect on the Young's modulus of rocks when subjected to dynamic cyclic loading. The expression of Young's modulus for rock materials suitable for medium- and low-strain-rate dynamic cyclic loading is established. Second, like the variation of Young's modulus, the expressions of cohesion and internal friction angle with strain rate and damage variable for rock materials under dynamic cyclic loading are also established. Then, a dynamic constitutive model for rock materials considering strain rate, damage effect, and the coupling of the former two effects is constructed based on the static constitutive model proposed by a previous study. Finally, the dynamic and static constitutive models are applied to simulate the behavior of a T2y6 marble and a material similar to basalt under uniaxial constant amplitude dynamic cyclic loading and triaxial damage-controlled cyclic dynamic loading (using increasing mean and amplitude stress). The results show that the results obtained by the proposed model, in terms of reproducing the compressive strength, Young's modulus, and residual strain in cyclic tests of the two rock materials, are much better than those predicted by the static constitutive model. [ABSTRACT FROM AUTHOR]

2 The schematic and simplified flowchart of the cyclic shear loading test device Note, to improve the accuracy for cyclic shearing, there are two separate shear servo valves, one for each shear jack. 1) specialized in cyclic shear loading for rock joints was developed, and tested on artificial joint models under conventional monotonic shear test, and cyclic shear tests with simple and complex stress path. 4a were obtained by setting the stop target as: 2 mm of shear displacement under 0.5 MPa of normal stress, then - 3 mm of shear displacement under 1 MPa of normal stress, followed by 4 mm under 1.5 MPa, ..., until 8 mm of shear displacement at 4 MPa of normal stress was reached. Keywords: Rock joint; Direct shear; Cyclic shear; Shear apparatus EN Rock joint Direct shear Cyclic shear Shear apparatus 4321 4327 7 08/06/21 20210801 NES 210801 Introduction The mechanical behavior of rock joint has always been an important issue in the field of geotechnical practice. [Extracted from the article]

Study Design. A prospective consecutive case study. Objective. This study aimed to assess the accuracy of computed tomography perfusion (CTP) in evaluating the vascularity of thoracolumbar metastases and to determine the impact of combining CTP with preoperative embolization on reducing intraoperative blood loss during separation surgery. Summary of Background Data. Surgery for thoracolumbar metastases is a complex procedure with the potential for substantial blood loss. Therefore, assessing tumor vascularity before surgery and taking measures to minimize intraoperative blood loss is essential. Methods. A total of 62 patients with thoracolumbar metastases were prospectively enrolled. All patients underwent separation surgery using the posterior approach. Before surgery, the vascularity of the metastases was evaluated using CTP. On the basis of the CTP results, patients were categorized into hypervascular and hypovascular groups. Preoperative angiography and embolization were performed for the hypervascular group. Clinical data were abstracted, including intraoperative blood loss, perioperative complications, visual analog scale score, neurological status, and the accuracy of vascularity evaluation by CTP confirmed by angiography. χ² testing was used to compare categorical variables, whereas independent sample t tests were used to compare continuous variables, with paired t tests used to assess differences from preoperative to postoperative time points. Results. The mean intraoperative blood loss was 485±167 and 455± 127.6 mL in the two groups, respectively. The accuracy of vascularity evaluation by CTP was 100%. In the hypervascular group, 80.6% of the patients experienced at least one level of improvement in neurological status, while the hypovascular group had 81.5% of patients with similar improvement. None of the patients experienced neurological deterioration. There was a significant reduction in visual analog scale scores in both groups after the operation. Conclusions. The vascularity of thoracolumbar metastases could be accurately evaluated using noninvasive CTP. When combined with preoperative embolization, this approach effectively and safely reduced intraoperative blood loss in the setting of separation surgery. [ABSTRACT FROM AUTHOR]

The bearing capacity of large rectangular foundations on soil subjected to combined loading [simultaneously subjected to vertical load (V), overturning moment (M), and horizontal or lateral load (H)] is one of the central topics of interest to geotechnical engineers as it relates to the design of foundations such as ground anchorages of bridges, offshore structures, and gravity dams. To solve this problem, a combination of numerical simulation and theoretical research was used, and a stability evaluation model of large rectangular foundations on soil subjected to combined loading was established. First, an empirical equation for the failure envelope in the V‒M‒H loading space of rectangular foundations was developed. Second, the safety factor for load-path dependency (LPD) was established by considering the combined effects of V, M, and H, the stability evaluation model for large rectangular foundations on soil subjected to combined loading was constructed by proposing a method for calculating the LPD safety factor based on the V‒M‒H failure envelope. Last, the accuracy and effectiveness of the stability evaluation model proposed was verified. The proposed model provides a convenient means of calculating the stability of large rectangular foundations on soil under combined loading. The model was applied to the optimal design of a gravity anchorage project of a suspension bridge, which proves that the proposed model is rational and efficient. [ABSTRACT FROM AUTHOR]

The rock discontinuity orientation has a significant impact on the engineering stability. This paper proposes a semi-automatic method for identifying the orientation of rock discontinuities based on 3D point clouds. First, the normal of each point is calculated by k-nearest neighbors (KNN) and least squares (LS) algorithms. Then the point normal is regarded as the input parameter and the number of joint sets can be determined by density-based spatial clustering of applications with noise (DBSCAN). For each joint set, the point coordinate is considered as the input parameter, and DBSCAN is employed again to obtain the individual joint plane. Finally, the orientation of each joint plane is computed by LS algorithm, and the weighted mean of the orientation based on size is taken as the orientation of each joint set. The correctness of the method is verified by two standard geometric solid objects, and it is applied in real slope engineering to identify the orientation of rock discontinuities. The results are consistent with those observed in the field, and the differences with other methods are discussed. In comparison with the open source procedure DSE and the commercial software ShapeMetrix, the proposed method shows remarkable advantages in terms of precision and accuracy, and can preserve more point cloud information. This study extends the method of semi-automatic identification of rock discontinuities and can provide a reference for similar engineering. [ABSTRACT FROM AUTHOR]

Support damage is a typical hazard scenario associated with tunnel boring machine (TBM) drives in the squeezing rock condition. The stress release of the rock mass and the improvement of the support capacity are two effective methods to prevent support damage. The stress in the rock mass can be released by allowing a certain amount of overexcavation. The support capacity can be evaluated by solving the required support pressures corresponding to different critical strain levels. This paper aims to achieve a better understanding of preventing support damage for TBMs in the squeezing condition by quantitatively analyzing the overexcavation and the required support pressure. A semianalytical solution of the ground reaction curve is obtained. A simplified method of solving the support pressure with specific rock displacement is proposed. Based on the two solutions, the procedures for solving for the overexcavation and the critical support pressure are presented. Corresponding to the critical strain levels of 1%, 2.5%, 5%, and 10%, the response surfaces for critical support pressures in relation to the Geological Survey Index (GSI) and in situ stress are obtained via the nonlinear regression method. The influences of GSI, in situ stress, and the mechanical parameters of the concrete lining and shield on the size of the overexcavation are comprehensively investigated. A method to guide support design in the squeezing rock mass is proposed. Three tunnel cases are presented to demonstrate the application of the method, and three case histories that encounter support failures are discussed to illustrate the appropriate design measures through the proposed method. [ABSTRACT FROM AUTHOR]

Seismic analysis of tunnels close to or crossing seismogenic faults is a complex problem, which is often neglected at the design stage for the lack of specific codes or guidelines and also because underground structures are considered less vulnerable than that of the corresponding above-ground facilities. Near-fault ground motions are generally assumed to providing more powerful energy to tunnel structures. Therefore, a recently developed velocity pulse equivalent model is proposed to synthesize the artificial near-fault pulsed ground motion for the seismic response behavior of the tunnel structure. A newly proposed nonlinear dynamic time history methodology, the incremental dynamic analysis method, is introduced into the analysis of seismic performance and fragility for tunnel structures. This study takes the Zheduoshan tunnel as a case study to illustrate the effects of velocity pulse on the seismic response behavior and seismic performance. The applicability of different seismic intensity measures is preliminarily discussed, and the vulnerability of the tunnel structure at different characteristic locations is analyzed. Afterward, the seismic vulnerability probabilities of the tunnel structure under the action of the near-fault pulsed ground motions and the far-field ground motions are presented, and then, the failure probabilities of the tunnel structure under the three-level support requirements are obtained. Research results provide an objective assessment of the velocity pulse effects and acts as a reference for the likely seismic damage assessment of tunnel structures. [ABSTRACT FROM AUTHOR]

Safe construction and operation of tunnels in high seismic risk regions require special aseismic design. A possible solution to this issue is to consider the earthquake damage that a tunnel may suffer beforehand in the process of engineering rock mass classification during the geotechnical investigation phase. Then, the tunnel support system is designed with this modified classification result. To verify this hypothesis, this work investigates the Chinese engineering rock mass classification system, the basic quality (BQ) rating system, considering seismic effects. The main contribution of the current work is to quantitatively modify the rock mass intactness index Kv in the BQ system considering the potential earthquake damage under various levels of design peak ground acceleration. The procedure to obtain the rock mass basic quality index considering the design peak ground acceleration is proposed and verified with real field data from the 2008 Wenchuan earthquake. This approach is a promising enhancement of the empirical methods for considering the seismic effects for tunnels that require special design against possible earthquake impacts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fractions and transformation of P together with key metals are researched. • P tends to transform into more stable P fractions during pyrolysis. • TP, IP, HCl-P and HCl-Ca/-Mg increases as pyrolysis temperature increases. • NaOH-P is the dominant fraction, enabling sludge biochars to act as a P fertilizer. Pyrolysis of sewage sludge (SS) to SS biochars (SBCs) is a promising method for maximizing the utilization of phosphorus (P) in SS. A comprehensive understanding of P distribution and transformation in SS and SBCs is fundamental for the recycling of P from these materials as a soil amendment. Most studies have focused on P itself in SS and SBCs, without examining the changes of closely related metals (e.g., Al, Ca, Fe and Mg) that are typically co-extracted with P. Thus, in this study, a series of investigations were performed in which an improved Hedley sequential extraction method of P was used together with advanced analytical techniques to determine the distribution and transformation of P in SS and SBCs. Increasing the pyrolysis temperature increased concentrations of total P and inorganic P in SS and SBCs. In addition, P and Al species in SS and SBCs were predominantly sodium hydroxide-soluble species—denoted NaOH-Al and NaOH-P—and increasing the pyrolysis temperature increased their concentrations in SBCs, especially for NaOH-Al, from 28.35 ± 2.56 mg/g to 38.18 ± 3.29 mg/g. Ca, Mg and Fe were predominantly extracted by HCl solution, showing that HCl-extracted P comprised not only Ca-P but also Fe-P, Mg-P and Al-P. Spectroscopic analyses revealed that the concentration of hydroxyapatite (HAp) in SS and SBCs increased with the pyrolysis temperature, and Al-P was the dominant species in both SS and SBCs. Thus the pyrolysis of SS affords SBCs that are a relatively stable pool of P for plants, enabling SBCs to serve as a slow-release P fertilizer in soil. These findings further contribute to fundamental knowledge on the recycling of P during integrated waste management. [ABSTRACT FROM AUTHOR]

In a strong earthquake, not only a large number of coseismic landslides are triggered, but relaxation and cracks in the rocks and soils are induced, which make these rocks and soils vulnerable to instability during subsequent rainfall; thus, strong earthquakes always have long-term effects on landslides. The geo-hazards along the Zhaotong-Qiaojia road in the 2014 Ludian earthquake (Ms 6.5) of Yunnan Province, China, were investigated, and the Ganjiazhai giant landslide was chosen as a case study. First, using the limit equilibrium analysis and Newmark method, the critical seismic intensity of the landslide before the earthquake was evaluated. Secondly, the dynamic failure process of the landslide under the measured ground motion was simulated with the discontinuous deformation analysis method. Lastly, based on stress–seepage coupling analysis and precipitation data from Ludian meteorological station, the stability of the landslide during subsequent rainfall after the earthquake was predicted. The results show that the critical seismic intensity was within degrees VIII–IX, which is consistent with the results of the earthquake damage investigation. The dynamic failure process can be divided into four stages, and four scarps formed; the potential sliding zones during the subsequent rainfall were at the first scarp and the fourth scarp, and their critical rainfall amounts were 35–40 mm and 55–60 mm, respectively. In this paper, failure process simulation and stability prediction of the landslide before, during, and after the strong earthquake are presented, which provide analysis methods for the dynamic stability of landslides in the meizoseismal area. [ABSTRACT FROM AUTHOR]

A majority of hypertensive patients will end up suffering uncontrolled hypertension, which is partly due to poor medication adherence. This paper aimed to review a range of interventions that could improve anti-hypertensive medication adherence. Literature search was conducted using PubMed, Scopus, Medline, and Science Direct databases, with publication dates confined to between October 2009 and October 2019. Eventually, only 11 studies were used for this study. It was found that interventions that are based on or include patient education, patient interviews, patient reminders, self-management and behavioural modifications have the potential to improve patients' adherence to anti-hypertensive therapy. Most successful interventions involve patient reminder, self-management and behavioural intervention. [ABSTRACT FROM AUTHOR]

In the uniaxial compressive test, the strain energy density is expressed as follows: 2 HT ht Graph 3 HT ht Graph Graph: Fig. According to the strain equivalence hypothesis: 14 HT ht Graph 15 HT ht Graph Graph: Fig. [Extracted from the article]

Earthquakes are a major landslide trigger, and evaluation of the dynamic stability of landslides under seismic action is very important. The Yanyangcun landslide, which is located at route marker K92 of the Xianggelila to Lijiang expressway in Yunnan Province, China, was chosen as a case study. Using the three-dimensional finite difference method and the unbalanced thrust method, three mechanical indices of the sliding zone, including the volume ratio of the elastic or plastic elements, the permanent displacement, and the residual thrusts of the slices, were calculated to evaluate the progressive failure and dynamic stability of the landslide when exposed to different intensities of seismicity. The safety factor of the landslide with reinforcement measures was also assessed. The critical peak seismic acceleration was about 2.29 m/s2, between earthquake intensity of VIII degree and IX degree. The landslide experienced progressive failure by means of shear at the leading edge, tension at the trailing edge, and immobilization of the middle part. The middle part of the sliding zone underwent a "locking effect," which could effectively resist the immobilization of the plastic zones of the leading edge and the trailing edge. With reinforcement measures, the dynamic stability of the landslide under VIII degree and IX degree events satisfied the allowable safety factor of the local specifications. The results provide guidance for disaster prevention and aseismic design for the Yanyangcun landslide, and can also be used as reference information for dynamic stability evaluation of other landslides threatened by earthquakes. [ABSTRACT FROM AUTHOR]

As the weak structure and main seepage channel of rock mass, the discrete fracture network (DFN) has a significant influence on the physical and mechanical properties of rock mass. In this paper, based on the rectangular joint model, two algorithms are proposed to realize the precise modeling of the DFN in any polyhedron. First, the equivalence of DFN modeling with the rectangular joint model and the elliptical joint model is theoretically deduced. On this basis, the chain splicing algorithm suitable for the rectangular joint model is proposed, which can generate the DFN model according to the actual distribution of joint spacing, trace, and bridge length. Aiming at the concave boundary in the model domain, the segmentation‐stitching operation is put forward, and the continuity of the joint when passing through the interface is ensured. Finally, the effectiveness of the above algorithm is verified by several simple cases, and the relationship between the size of the geometrical representative elementary volume (REV) and discontinuity parameters is discussed. The results show that when the mean values of the joint distribution parameters are the same, even if the distribution rules are different, the number of joints generated in the same spatial region is approximately equal. The size of the geometrical REV is independent of the spacing and bridge length and is approximately three to five times the mean of the trace. The relevant algorithms and conclusions in this paper can be used as the basis for subsequent rock mass stability analysis and seepage calculation. [ABSTRACT FROM AUTHOR]

Soil-rock mixture (SRM) shows complicated mechanical behaviors due to their complex compositions and structures, leading to challenging instability problems during the construction process. Typical SRM are composed of rocks with high strength and fine grained soils, and the mechanical characteristic is largely controlled by the rock block proportion (RBP) and component properties. It is noted that the rock sizes of natural SRM make it difficult for laboratory or in situ tests. There are few studies on empirical formulas to predict the mechanical characteristics of SRM. In this study, the nonlinear relationship between SRM shear strength and RBP was investigated, and an empirical formula predicting the shear strength of mixtures consisted of strong rocks and a weak soil matrix was proposed. For this purpose, a database of shear strength and uniaxial compressive strength (UCS) of SRM with different RBPs was built firstly on the basis of the laboratory test results from previous literatures. In order to focus on the interactions of rock blocks and soil matrix in SRM, a RBP range of 30–90% was set as the applicable range of the empirical formula and both of the compositions are held to provide shear resistance in the applicable range. Subsequently, a nonlinear equation to calculate the shear strength of SRM with RBP range of 30–90% was proposed using regression analysis considering the strengths of components and soil-rock contact faces. Several representative properties of rocks and soil matrix, such as RBP, UCS of the matrix (UCSm), and the friction angle of the blocks (φblock), were chosen as the input parameters based on the mechanical properties of SRM. An additional parameter "A" was used to describe the connect strengths of the soil-rock contact faces. In addition, uniaxial compression tests and large-scale direct shear tests were performed on the Taoyuan SRM samples. The test results and other measured data from the database were used to compare with the corresponding estimated values. The results demonstrated that the empirical approach could predict the shear strength with R2 = 0.75 and can be considered a practical tool in engineering designs when mechanical tests are not available. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to investigate the relationship of serum hemoglobin (HB) level with disease activity and structural damage in Chinese patients with rheumatoid arthritis (RA). Methods: A total of 890 RA patients and 890 normal subjects were enrolled in the case-control study. A HB threshold of< 110 g/L (women) and < 120 g/L (men) was used to determine anemia. All the patients were divided into three groups: non-anemia group (HB ≥ 120 g/L (male) or 110 g/L (female)), mild anemia group ((90 g/L < HB < lower limit of normal), and medium to severe anemia group (HB ≤ 90 g/L). Serum HB level and anemia prevalence between RA patients and normal subjects were compared. Associations of HB level with disease activity, structural damage, and function of joint in different groups were also investigated. Results: The average of HB level in RA was (109.08 ± 17.96)g/l, which was lower than that in controls (136.75 ± 14.57)g/l (P < 0.001). Anemia was observed in 47% of the RA patients, while prevalence of anemia in control group was only 4.4%. In RA group, percentages of non-anemia, mild anemia, and medium to severe anemia were 47%, 38%, and 15%. Compared with non-anemia RA patients, RA patients with anemia had higher disease activity, severer structural damage and worse function of joint (P < 0.001). With the increase of anemia, the disease activity, structural damage, and dysfunction of joints increased significantly (P < 0.05–0.001). Linear regression analysis showed that HB level was negatively correlated with disease activity parameters, degree of joint destruction, and function (P < 0.05–0.001). Logistic regression indicated that serum HB level was protective factors for disease activity and structural damage in RA (P < 0.001). Conclusion: HB level was significantly related to disease activity and structural damage in RA patients. Key Points • Inflammatory anemia was popular (about a half) in patients with RA. • HB level was related to disease activity and structural damage in RA patients [ABSTRACT FROM AUTHOR]

The stress state and principal stress axis changes of the stress-field tensor are analyzed during the advancement of a tunnel face on the basis of a given case study of the Jinping II Hydropower Station in China. First, the prevailing pole diagram in geology is used to illustrate the rotation of the stress axes as the tunnel face advances. The results show that the orientation adjustments of principal stresses in different positions near the tunnel boundary share common characteristics. The major and minor principal stress axes ahead of the tunnel face will rotate to intersect with the excavation surface at an angle, with the intermediate principal stress axis being almost parallel to the excavation surface. Furthermore, the stress triaxiality that is commonly used to indicate the deformation and damage of metal materials is introduced to describe the stress state change of the excavation-induced stress. The stress triaxiality is found to represent the stress state change due to the variation in both the magnitude and orientation of the stress-field tensor. According to the physical meaning and the change law of the stress triaxiality, stress disturbance during tunnel excavation can be divided into four stages, and the stress disturbance zone is divided into a strong disturbance zone and a weak disturbance zone. The disturbance characteristics of different stages and the distribution patterns of various zones are analyzed, which may be useful for practical application in the design and construction of rock tunnels. [ABSTRACT FROM AUTHOR]

Objectives: To explore the prevalence and risk factors of osteoporosis (OP) and vertebral osteoporotic fracture (VOPF) in patients with rheumatoid arthritis (RA). Methods: Anteroposterior and lateral X-ray examination of the vertebral column (T4-L4) was used for the semi-quantitative assessment of VOPF. Bone mineral density was measured by dual-energy X-ray absorptiometry. Results: Of 865 RA patients, the prevalence of OP and VOPF was 33.6% and 20.2%, respectively. Patients with OP or VOPF were older, and had longer term use and a larger daily amount and cumulative dose of glucocorticoids (GCs), longer disease duration, and higher Health Assessment Questionnaire (HAQ) scores and Sharp scores than patients without OP or VOPF (P < 0.05). OP was also correlated with higher disease activity. The patients treated with GCs had higher incidences of OP and VOPF than the patients without GCs (P < 0.05). The cutoff values in the area under curve (AUC) of the daily dose or treatment course of GCs-VOPF were 9 mg and 37.5 days. Older age, female sex, and a higher Sharp score were risk factors for OP in RA patients, while higher BMI was a protective factor. Older age and a high GC daily dose were risk factors for VOPF in RA patients. Conclusions: RA patients have a high prevalence of OP and VOPF. Older age, female sex, lower BMI, and higher activity and severity of RA are closely related with OP. Older age and a higher GC daily dose are risk factors for VOPF in RA patients. Key Points • Older age, female sex, lower BMI, and a higher Sharp score were risk factors for OP in RA patients. • Older age and a high GC daily dose were risk factors for VOPF in RA patients. • OP and VOPF in RA patients were correlated with longer disease duration and higher severity of RA. [ABSTRACT FROM AUTHOR]

It is not widely accepted that the dynamic strain rate experienced by a rock mass during an earthquake is lower than that during a high strain rate scenario such as an explosion or a rock burst. The present study investigated the problem of determining the mechanical properties of rock considering earthquake effects using experimental tests and empirical formulas. First, to obtain the most concentrated frequency band of earthquake energy, a statistical analysis was conducted to obtain the response spectra of ground motion records near the example projects. The mean response spectrum was then fitted with a design response spectrum formula. The most concentrated frequency band of earthquake energy was then determined with the flat segment of the design response spectrum. Based on this frequency range, cyclic loading–unloading testing that simulated the earthquake effect was conducted on rock samples. The strain rate range experienced by rocks during an earthquake was then obtained. This strain rate range is between the quasi-static and intermediate strain rate ranges and is significantly lower than the high strain rate range. Based on this strain rate range, dynamic triaxial compression tests were conducted on igneous rock specimens from the case study areas. It is confirmed that the fit of the dynamic compression test results with the Hoek–Brown (HB) criterion is more accurate than that with the Mohr–Coulomb criterion. The HB strength envelope under static conditions can be used to predict the seismic strength behaviors, requiring an update of only the intercept of the envelope. Thus, the HB strength criterion considering the seismic effect was obtained. Moreover, the seismic modulus of the intact rock can be estimated with the values of the uniaxial compressive strength (UCS) under different strain rates and the modulus ratio, which was found to be independent of the strain rate. Hence, it is practical to estimate the mechanical properties of rock masses in consideration of seismic effects with the seismic HB strength criterion and the Hoek and Diederichs equation based on the UCSs under various strain rates. Ultimately, the rock mechanical properties in consideration of seismic effects were estimated via the proposed approach for the Baihetan hydropower plant project as an example. [ABSTRACT FROM AUTHOR]

Introduction: Diabetes mellitus is a major risk factor for chronic kidney disease (CKD). Thus, making routine screening among the diabetic group is necessary in order to reduce the burden of the disease. As such, various risk prediction models including QKidney model have been developed for early detection of CKD. However, the Qkidney model has not been validated in Malaysia. This study aimed to evaluate the performance of QKidney model in predicting a 5-year risk of developing CKD in a cohort of type 2 diabetes mellitus (T2DM) patients in the primary care setting. Methods: A total of 377 T2DM patients attended the primary care clinic at the town of Rawang, aged 30-74 years old, and free of CKD outcomes at baseline were recruited and followed-up for 5 years. Their CKD risk was calculated using the QKidney model. The predictive performance of QKidney model was assessed through discrimination and calibration analyses. Results: At the end of the 5-year follow-up, a total median QKidney score was 3.9% (IQR: 5.9). The median QKidney score of male participants (7.3%) was significantly higher than that of the females (3.0%) (p < 0.001). The QKidney model has a moderate discrimination in which the area under the receiver operating characteristic curve was 0.748, with good calibration (χ² = 13.039, p = 0.111). Conclusion: It was found that the QKidney model had a moderate discriminative ability with good calibration. When taken together, it was suggested that the QKidney model could be utilized to predict a moderate-to-severe CKD risk in Malaysians with T2DM. [ABSTRACT FROM AUTHOR]

The stability of a colluvial slope, which is different from a rock or soil slope, is determined by the properties of both the bedrock and the colluvium. Coupled with artificial excavation and environmental effects, the stability factors of such slopes are complicated. To rapidly and effectively evaluate the risk of a colluvial cutting slope, a risk evaluation system for this type of slope is established herein. First, an evaluation index system is established, and reasonable risk evaluation indices are selected. Second, the fuzzy analytic hierarchy process (FAHP) is applied, a fuzzy pairwise comparison matrix, that must satisfy a consistency test, is constructed, and the weight of each index is determined. Third, the risk evaluation grades are divided into 4 risk grades, and the risk evaluation criteria for each basic index are determined. Finally, the three-level fuzzy comprehensive evaluation (FCE) method is applied, the membership function for each index is constructed, the membership degree is calculated, and the risk grade of the colluvial cutting slope is determined. This risk evaluation system is used to evaluate the risks of 148 colluvial cutting slopes along the Xiaomengyang-Mohan highway in Yunnan, China. The results show that there are 24 slopes of low risk (grade I), 85 of medium risk (grade II), 22 of high risk (grade III), and 17 of very high risk (grade IV). The evaluation results obtained are in good agreement with the actual slope instability states: failure occurred in 15 out of 85 slopes of risk grade II, 13 out of 22 slopes of risk grade III, and 16 out of 17 slopes of risk grade IV. This application demonstrates that the proposed risk evaluation system for colluvial cutting slopes is universal, and stable and that the calculation results are objective. [ABSTRACT FROM AUTHOR]

Objective RA is a systemic auto-immune inflammatory disease that can lead to local bone erosions and generalized osteoporosis (OP). The aim of this study was to investigate the relationship between systemic osteoporosis and local bone erosion with RA patients in the Chinese population. Methods In total, 1235 patients with RA and 158 normal subjects were enrolled in this study. Clinical and laboratory features were recorded in detail. Information about functional class and physical activity was collected using specific questionnaires. Dual-energy X-ray absorptiometry was used to measure BMD. The MECALL castor-50-hf model X-ray scanner was used for two-hand (including wrist) photographs. Results The median Sharp scores differed significantly between the normal bone mass group, osteopenia group and OP group (P < 0.001). There was a modest negative linear correlation between Sharp and HAQ scores and longer disease duration (P < 0.001). There was a clear increasing trend in Sharp score, incidence of OP and HAQ score in the different DAS in 28 joints (DAS28) activity groups (P < 0.001). Spearman's correlation test showed that Sharp and HAQ scores were negatively correlated with BMD at all measured sites (femoral neck, total hip and L1–4) (P < 0.001). Logistic regression indicated that age, female gender, and Sharp and HAQ scores were independent risk factors in the occurrence of OP in RA patients. The use of DMARDs and BMI were protective factors for OP. Conclusion These results suggest that BMD is associated with local bone erosion among Chinese patients with RA. Local bone erosion is closely related to clinical symptoms and BMD in patients with RA. [ABSTRACT FROM AUTHOR]

Regression analysis method has been extensively used to predict tunnel during excavations. This paper applies the method to solve for the tunnel strain for a circular opening in a strain-softening rock mass. Support pressure, in-situ stress and geological strength index (GSI) are three important geological parameters that are simultaneously considered in evaluating tunnel strain. A numerical procedure of the strain-softening rock mass is incorporated to solve for tunnel strain with a series of GSI, in-situ stress and support pressure. A detailed result of the tunnel strain is solved using the repeated numerical procedures. A nonlinear regression model for predicting tunnel strain is obtained through analysing the result with the regression method. Twelve fitting equations are considered in the regression model, correlating the tunnel strain with the support pressure, GSI, initial stress and critical softening parameters. The analysis framework is validated by comparing the calculated tunnel strain to that predicted by existing studies. The influence of the critical softening parameter on tunnel strain and the radius of the plastic zone are investigated. The response surfaces of tunnel strain versus the initial stress and support pressures for different rock mass qualities with various softening behaviours are also analysed. Then a guidance of the support design is derived based on the regression model and is demonstrated in an actual tunnel case with field measurements. [ABSTRACT FROM AUTHOR]

Summary Seismic stability analysis of a rock block is an important issue in the field of rock mechanics and rock engineering. To solve this problem, the block theory and the Newmark method are combined, and a general method for seismic response of a rock block is introduced. First, the formation method of a three‐dimensional rock block, which includes establishing a topological relationship among the block‐polygon face‐edge‐vertex and dividing a complex block into convex subblocks, is presented, and the simplex integration method is employed to calculate the volume of a rock block and the areas of the polygonal faces. Second, the assumptions and algorithms of the general method for seismic response of a rock block are detailed. The dynamic analysis is carried out in time step. In each time step, the key technologies including analysis of the seismic force and motion mode, trial of the incremental displacement, check for the block entrance, and update of the motion parameters are performed in order. Last, two verification examples and three application examples including a wedge, a rock block of slope, and a combined rock block are used to analyze the correctness and practicality of the general method. The results show that, for a given ground motion record, the Newmark program can effectively simulate the dynamic response process of the motion mode, velocity, and safety factor of the rock block, and the permanent displacement under the earthquake action is obtained, which provides a quantitative parameter to evaluate the dynamic stability of a rock block. [ABSTRACT FROM AUTHOR]

Background: Efficacy of anti-tumor necrosis factor (anti-TNF)a treatment in patient with active ankylosing spondylitis (AS) had been proved by many clinical studies. Inflammation and new bone formation in spine were two pivotal aspects in AS. TNF a inhibitor could eliminate inflammation including clinical and laboratory inflammatory manifestation. Paradoxical results whether TNF a antagonist could delay radiographic progression in AS were often been reported simultaneously. Objectives: To review the literature about the effect of TNF a inhibitor on radiographic progression and disease activity in patient with AS. Methods: We conducted a comprehensive search including Medline, EMBASE and the Cochrane Library from 1 January 2000 to 15 August 2017. Two reviewers independently supplemented with hand searching for the reference lists of inclusion. All trials focusing on radiographic progression or disease activity in patients with AS treated with anti-TNF a agents. Primary outcomes were modified Stokes AS Spinal Score (mSASSS), as well as Bath AS disease activity index (BASDAI) and Bath AS functional index (BASFI). Two reviewers independently selected studies and analyzed data. Methodological quality was assessed using the Newcastle-Ottawa scale (NOS). We pooled effects recorded on different scales as Standardized mean differences (SMDs) with 95% confidence intervals (CIs) using randomeffects models. Results: We included 14 studies of low to moderate risk of bias with 3,186 patients, compared with control group, there was no effect of mSASSS changes (SMD¼-0.12, 95% CI: -1.17-0.93, p value¼.82, I2¼95%) and follow-up (SMD¼0.03, 95% CI: 0.21-0.26, p value¼.82, I2¼36%) estimation in anti-TNF a group. However anti-TNF a agent treatment led to remarkable improvements on both Bath AS disease activity index (BASDAI) (SMD¼1.06, 95% CI: 0.22-1.89, p value¼.01, I2¼96%) and Bath AS functional index (BASFI) (SMD¼0.93, 95% CI: 0.24-1.92, p value¼.01, I2¼97%) scores at 12 weeks. Conclusion: Our meta-analysis found no significant effect on delaying radiographic progression in AS treated with TNF a inhibitor, although TNF a inhibitor could do improve significantly disease activity and physical function in AS. [ABSTRACT FROM AUTHOR]

This work describes investigation of the long-term strength of marble rocks in a stability assessment of deeply buried Jinping headrace tunnels. First, a series of long-term axial compression tests were conducted, with which the fitted long-term strength curve for marble rocks was determined. Then, Potyondy's parallel-bonded stress corrosion (PSC) model was used to perform a numerical static fatigue test. The PSC parameters of the marble rocks were back-analyzed based upon the long-term loading tests. Finally, a small-scale Particle Flow Code (PFC)-based model was constructed for a headrace tunnel, and the long-term stability of the modeled tunnel was assessed. [ABSTRACT FROM AUTHOR]

Determining the shear strength of rock joint surfaces is a fundamental problem in the fields of rock mechanics and engineering geology. To obtain the cyclic shear strength of rock joint surfaces under cyclic shearing conditions, an improved formula is proposed. First, cubic splitting tests are used to fabricate joint surfaces and prepare experimental specimens with simulated materials. Second, a series of laboratory cyclic shear tests and data analysis are conducted to investigate the effects of the normal stress, the number of shearing cycles, the rock wall strength, and the surface roughness on the mechanical and morphological properties of the rock joints. The maximum shear strength of the joint surface increases with the normal stress, the rock wall strength, and the joint surface roughness. Considering morphological properties, the normalized values of the indices decrease with the normal stress, the number of shearing cycles, and the joint surface roughness increase, while they increase with increasing rock wall strength. Third, the accuracy of the Adhesive Friction Theory-Barton empirical formula is verified by fitting the experimental data to calculation results. Finally, based on the negative exponential degradation assumption, a new formula is proposed to calculate shear strength under cyclic shear conditions. The proposed calculation method can provide a theoretical reference for improved safety during engineering and design. [ABSTRACT FROM AUTHOR]

In this work, we present a peridynamic-based simulation method for modeling quasi-static fracture propagation in isotropic and anisotropic rock within the framework of peridynamic least square minimization (PDLSM). The original isotropic elastic PDLSM is further extended to investigate fracture propagation in anisotropic materials in this study. The proposed AN-PDLSM model integrates an anisotropic model in fracture mechanics to analyze the failure process of anisotropic rocks. An important advancement in this research lies in the incorporation of the maximum energy release rate criterion (MERR) into the PDLSM framework for the first time. This enhancement enables accurately determining crack propagation and the associated crack angles. The proposed model utilizes the energy release rate calculated through the J-integral method to assess bond breakage, and it employs a mesh-independent, piecewise linear fracture model to describe crack propagation. The proposed method fully combines the merits of traditional fracture mechanics with the unique capabilities of peridynamics. To demonstrate the effectiveness of the proposed model, a simulation of fracture evolution in isotropic plates subjected to semi-circular bending tests is presented and compared with experimental results. It is shown that the proposed model accurately replicates fracture trajectories in isotropic specimens. In the context of anisotropic rock, the effect of a weak coefficient on crack morphology is discussed in order to obtain a suitable value. Additionally, the impact of bedding angles on fracture paths through our proposed model is also explored, revealing excellent agreement with experimental results. The findings in this research demonstrate that the proposed AN-PDLSM model is exceptionally proficient at capturing the intricate, oscillating crack paths observed in anisotropic rock materials. [ABSTRACT FROM AUTHOR]

As a typical heterogeneous material, the macroscopic mechanical properties of rocks are influenced by factors, such as the type, size, and spatial distribution of internal mineral particles. To study the influence of microscopic heterogeneity on the nonlinear mechanical behavior and fracture process of rocks, DIP (digital image processing) technology and FDEM (finite-discrete element method) are used to establish numerical models that characterize the microstructures of three types of gabbro: coarse-grained, medium-grained, and fine-grained. First, CT (Computed Tomography) scan images were segmented and vectorized. Then, the model was calibrated based on uniaxial compression experiment results. Finally, numerical tests of uniaxial compression were carried out on the three heterogeneous models to explore the deformation characteristics, crack propagation laws, and energy conversion effects of the micro-heterogeneous structures of the three gabbros. Combined numerical and laboratory uniaxial compression experiments results, the results showed that micro-cracks in gabbro appeared at the boundary between clinopyroxene and plagioclase, and propagated continuously along the mineral interface, and the final crack distribution was controlled by the spatial distribution of mineral particles. In addition, the particle size of gabbro had a significant impact on the micro-crack propagation and macroscopic mechanical properties of the model. The finer the particle size, the smaller the heterogeneity, the higher the UCS (uniaxial compression strength) and E (elastic modulus), the faster the energy dissipation, and the stronger the brittleness of the rock. The results of this study conclude the macroscopic mechanical behavior and micro-failure mechanism of gabbro in the compressed state, and also provide technical support for the study of similar rocks. Highlights: Based on the FDEM and digital image processing technology, a numerical model is being created that can represent the micro-heterogeneity of gabbro. Compared the results of numerical and laboratory experiments, the differences in mechanical behavior of different grain sizes gabbros were revealed. Compared the energy dissipation and crack propagation modes of gabbros, the impact of grain size on the rock fracturing process was revealed. [ABSTRACT FROM AUTHOR]

Calibration is one of the most crucial and inevitable processes in vision technology, whose performance can significantly affect the measurement accuracy of the vision system. To compensate for coefficients of water factors, the conventional calibration technology for the underwater camera generally introduces several higher-order distortion coefficients, which, unfortunately, suffer poor stability, low efficiency, as well as computational complexity. To overcome these drawbacks, a newish calibration method based on equivalent focal length is proposed in this paper. The method takes the refraction distortion of water factors as equivalent focal length changing to cause. Applying the invariance principle of linear perspective projection, distortion correction should first be carried out. Subsequently, the internal and external parameters of the camera are calculated by using Zhang's calibration method based on the camera linear model, which simplifies the process of underwater camera calibration. Finally, the experimental results show that the calibration method can effectively improve the accuracy of the underwater camera. [ABSTRACT FROM AUTHOR]

The mechanism for the influence of near-fault ground motion on seismic issues for underground rock caverns has seldom been addressed, especially for caverns controlled by large geological discontinuities. In this paper, a nonlinear joint model was used to simulate the effects of unfavorable geological discontinuities under seismic excitation. The influence of near-fault ground motion on unfavorable geological discontinuities was analyzed using a large sample of ground-motion records collected from the NGA-West2 database. A damage potential index (DPI) for unfavorable geological discontinuities was proposed and discussed. The #1 surge chamber of the Baihetan Hydropower Plant, which is dominated by interlayer shear weakness zone (ISWZ) C2, was used as a study case to investigate the differences between pulse-type near-fault ground motion, non-pulse-type near-fault ground motion, and far-field ground motion. The results of the study indicate that (1) significant velocity and displacement as well as a stronger long-period response spectrum are key characteristics of pulse-type near-fault ground motions, whereas non-pulse-type near-fault ground motions display characteristics similar to those of far-field ground motions; (2) the velocity pulse is responsible for the destructive capabilities of near-fault ground motions; (3) the peak ground velocity (PGV) was shown to be the most suitable DPI of several ground-motion parameters for large geological discontinuities under seismic excitation (applicable to both near-fault and far-field ground motions); and (4) PGV was verified to be the most effective DPI for ISWZ C2 at the Baihetan #1 surge chamber. The cavern became fragile when subjected to near-fault ground motions, so special seismic reinforcement measures are recommended. These findings may provide a reference for the seismic design of underground caverns. [ABSTRACT FROM AUTHOR]