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The frequency of water inrush disasters severely affects tunnel construction, lives, and property. As a result, accurate forecasting of the danger of water inrush during construction is critical. This paper aims to create a progressive evaluation model for assessing water inrush risk during two stages: pre-construction and construction. The proposed model provides a static pre-construction estimation and allows dynamic updates based on previous predictions for unexcavated sections during construction. Initially, comprehensive multi-water inrush information was presented by analyzing 65 tunnel accidents of water during construction, including 12 evaluation indexes encompassing hydrogeology and excavation monitoring. Subsequently, the assessment model was constructed using a combined weighting method and non-linear attribute recognition theory. The information from dynamic monitoring on surrounding rock and seepage pressure is integrated, and feedback site data is used to dynamically modify the weighting of the indicators and update the projected predictions. This approach has been employed as a case study to evaluate the water inrush risk during the Qinling water transmission tunnel. The results demonstrate that the prediction outcomes of dynamic weights align well with on-site holes, exhibiting higher forecasting accuracy than other methods. This approach offers a novel perspective for accurately evaluating water inrush risk in tunnel construction. [ABSTRACT FROM AUTHOR]

With the rapid development of underground engineering, the problem of sudden surge water has become one of the main problems that restrict engineering safety. Grouting method is commonly used to seal the fracture water flow. However, grouting in flowing water streams still faces many challenges. In this study, a rough fracture model is established based on the Barton curve, and the effects of fracture roughness, water flow rate, fracture inclination, and grouting pressure are considered, and orthogonal tests are used to study the diffusion pattern of slurry under the four factors. According to the observed phenomena, there are four main diffusion patterns of the slurry: (1) full slurry coverage with no water passing through; (2) little coverage with watercourses and cavity areas along both sides of the fracture; (3) partial slurry coverage with no obvious watercourses but some cavity areas; and (4) less coverage with larger watercourses and cavity areas. The reduction rate of flow rate at the outlet before and after grouting was used to express the sealing effect. The results show that the degree of influence on the slurry sealing effect from strong to weak is fracture roughness, water flow velocity, grouting pressure, and fracture angle in order. A method to characterize the sealing effect by slurry coverage is proposed based on the final distribution of residual slurry. Considering the mutual influence between different factors, the sealing effect of two factors is analyzed in order to provide reference for engineering practice. [ABSTRACT FROM AUTHOR]

In seepage analysis, the value of the boundary conditions primarily determines the accuracy of the calculation results. The reservoir impoundment causes a redistribution of the underground seepage field and a change in the groundwater level. At present, the commonly used finite element simulation methods rarely consider the influence of boundary water level changes. To explore the influence mechanism of reservoir impoundment on the boundary water level, based on the Dupuit theory and numerical simulation experiment, the change in groundwater level at the boundary on the mountainsides after impoundment was investigated when the model range was 1400 m, and a correction method for the boundary water level was proposed. The results showed that the distribution of the seepage field before and after the correction was significantly different and cannot be ignored. Subsequently, a large-scale slope model was established. Comparing the numerical solution of the boundary water level with the corrected solution indicated that the maximum relative difference was only 1.4%, proving the reliability of the proposed method. Moreover, the calculation results of the discharge and groundwater levels were underestimated, as the groundwater level rise at the calculation boundary was ignored. The proposed method can correct the water level at the boundary of the model and effectively improve the calculation accuracy of seepage analysis. [ABSTRACT FROM AUTHOR]

The disasters caused by groundwater during underground cavern excavation, are inevitable and difficult to predict. In this study, transient seepage analysis was performed during the excavation of Qingyuan power station's underground caverns and drainage hole arrays. The drainage hole arrays around the caverns were simulated using a new method, and the groundwater surface during transient seepage analysis was confirmed with the hydraulic conductivity adjustment method, by using ABAQUS user subroutines USDFLD and GETVRM. By simplifying the drainage hole into face geometry, the proposed drainage hole simulation method could reach the accuracy of the widely used substructure method with half nodes of the computational boundary, and reflect the influence of drainage hole diameter on seepage analysis results. Moreover, a sensibility analysis of the diameter and space of drainage hole arrays could be conducted using one simulation model with the proposed finite element mesh type. Transient seepage analysis showed the evolutions of the groundwater level, flow rate and maximum hydraulic gradient of drainage holes and underground caverns, during the construction of Qingyuan power station. Such results could provide a reference for the creation of design and construction schemes. The previous excavation of the drainage hole arrays could control the seepage field, and reduce the flow rate and maximum hydraulic gradient of the underground caverns. This study may provide valuable reference to the design and construction of similar projects. [ABSTRACT FROM AUTHOR]

Loess tunnels are prone to collapse during construction. The risk assessment of loess tunnel collapse is therefore of great significance to prevent collapse accidents. An attribute recognition model of loess tunnel collapse risk assessment is established based on attribute mathematical theory. Several risk assessment indexes, including surrounding rock lithology, topography, excavation span, burial depth, groundwater, rainfall, and construction technology and management level, are selected according to the statistical analysis of 62 cases of loess tunnel collapse. The indexes are described using qualitative and quantitative methods, and the grading standards for each index are determined. The frequency statistic method is used to compute the evaluation index weights. Attribute measurement functions are established to calculate the single-index and synthetic attribute measures, and a confidence criterion is adopted to determine the loess tunnel collapse risk level. The constructed attribute recognition model is used to evaluate the collapse risk of four loess tunnel projects. The results are consistent with the actual construction conditions, which verifies the reliability of the evaluation method and provides a new method to evaluate the collapse risk of loess tunnels during construction. [ABSTRACT FROM AUTHOR]

The Qingyuan Pumped Storage Power Station is located in Liaoning, China and has large-scale water conveyance and underground powerhouse systems. In order to analyze the evolution of the flow rate, external water pressure, and hydraulic gradient of water conveyance and powerhouse systems or around them, a 3D equivalent continuum seepage finite element simulation model was established based on existing theories and a new drainage hole arrays simulation method was proposed in this study. The proposed method had approximate accuracy and was easy to model with fewer nodes and elements in comparison with the substructure method for complex hole arrays of diameter 5 cm. On the basis of four different conditions, the results show that the dehiscence of concrete lining lead to the peak values of the water conveyance flow rate, the water inflow of the powerhouse, and the water discharge of drainage hole arrays. The lapse of drainage hole arrays at a 50% rate resulted in the peak values of the external water pressure around the terminal of the diversion system and the hydraulic gradient around the upstream of drainage hole arrays. Besides, the hydraulic gradient around the downstream drainage hole arrays reached the peak value when the lower reservoir water level rose. [ABSTRACT FROM AUTHOR]

AbstractConcrete face rockfill dams, preferred for their adaptability in unloading and soft rock foundations, encounter significant deformation control challenges at increased heights. This study analyses the stress and strain of five Chinese dams, ranging from 179.5 m to 233.5 m, demonstrating improved structural responses by implementing high-modulus zones in the rockfill and concrete embedment. The findings reveal a direct relationship between rockfill settlement, concrete face slab deflection, and dam height. Incorporating a high-modulus zone and concrete embedment resulted in reduced rockfill settlement by 15% and 5.8%, concrete face slab deflection by 17% and 41.9%, and joint deformation by 10%–20% and 21.2%, respectively. This study is expected to support the deformation control of high-concrete-face rockfill dams. [ABSTRACT FROM AUTHOR]

Determining the representative elementary volume (REV) of fractured rock masses is the foundation for studying the properties of such rock masses using the equivalent continuum model. This paper focuses on estimating the REV sizes of a fractured rock mass, considering the linked trace length and fracture aperture in both linear and nonlinear flow regimes. To achieve this, Monte Carlo simulations were employed to create discrete fracture network (DFN) models based on the geometric characteristics of fractures. The linear element method, modified by the Forchheimer law, was used to calculate the equivalent permeability coefficient tensor K and the equivalent non-Darcy coefficient tensor β. These calculations were performed to determine the REV size of DFNs under nonlinear flow conditions. The findings of this study demonstrate a general consistency in the computed K values for the two flow regimes. It was observed that the REV size, determined by β value, exceeded that obtained using K for the identical fracture network. Furthermore, when considering the same flow regime, the REV size was found to be smallest when the fracture aperture remained constant, followed by cases where it was independent of the trace length and finally when it was correlated with the trace length. [ABSTRACT FROM AUTHOR]

The continuous migration and loss of small particles in fractured rock mass with water flow is the main cause of water inrush in fault zones. In this study, a fluid–solid coupling model for fault zone was established to study the complex coupling between the groundwater seepage and migration of broken rock mass, and reveal the mechanism of erosion-induced water inrush. The rock skeleton and broken rock mass in the fault zone were modelled by large skeleton particles and small filling particles, respectively, in 3D particle flow software while the fluid flow through the fault was modelled by the built-in computational fluid dynamics module. The numerical results show that: (1) with the increase of water pressure, the loss of filling particles increases continuously, and the whole seepage process can be divided into three stages: slow seepage, abrupt seepage and steady seepage, (2) the mass loss, porosity and permeability first increase slowly, then increase rapidly, and finally tend to be stable, (3) higher fine particle content are more likely to cause structural instability due to mass loss, thus increases the risk of water inrush and mud outburst. [ABSTRACT FROM AUTHOR]

Interfacial seepage on soil-structure interface is common in water-related engineering, such as dam, culvert, water tunnel, foundation pit, etc. As a weak part in the project, seepage failure on soil-structure interface has caused many project accidents. However, there are few studies on the seepage mechanism analysis of soil-structure interface. In this paper, a series of numerical tests of interfacial seepage are carried out using CFD-DEM coupling method. The seepage mechanism and characteristics of different soil layers in the seepage device are analyzed and a formula for calculating the critical hydraulic gradient of the interface is discussed. The main conclusions are as follows: (1) The seepage flow on soil-structure interface will go through three stages: stability stage, transition stage and particle erosion stage; (2) The porosity and flow velocity of soil on the interface are greater than those in the far-field soil at the beginning of seepage flow; (3) The particle erosion on the soil-structure interface occurs earlier and the erosion degree is more serious than that of the far-field soil; (4) The critical hydraulic gradient of the interface rises nonlinearly with the increase of the degree of soil compaction; (5) The formula for calculating the critical hydraulic gradient of the interface could predict the numerical test results well. [ABSTRACT FROM AUTHOR]

Seepage problems exist in water conservancy projects, groundwater research, and geological research, and hydraulic conductivity is an important factor that affects the seepage field. This study investigates the heterogeneity of hydraulic conductivity. Kriging methods are used to simulate the spatial distribution of hydraulic conductivity, and the application of resistivity and grain size is used to obtain hydraulic conductivity. The results agree with the experimental pumping test results, which prove that the distribution of hydraulic conductivity can be obtained economically and efficiently and in a complex and wide area. [ABSTRACT FROM AUTHOR]

With the rapid increase of city waste, landfills have become a major method to deals with municipal solid waste. Thus, the safety of landfills has become a valuable research topic. In this paper, Jiangcungou Landfill, located in Shaanxi, China, was investigated and its slope stability was analyzed. Laboratory tests were used to obtain permeability coefficients of municipal solid waste. Based on the results, the distribution of leachate and stability in the landfill was computed and analyzed. These results showed: the range of permeability coefficient was from 1.0 × 10–7cm sec–1to 6.0 × 10–3cm sec–1on basis of laboratory test and some parameters of similar landfills. Owing to the existence of intermediate cover layers in the landfill, the perched water level appeared in the landfill with heavy rain. Moreover, the waste was filled with leachate in the top layer, and the range of leachate level was from 2 m to 5 m in depth under the waste surface in other layers. The closer it gets to the surface of landfill, the higher the perched water level of leachate. It is indicated that the minimum safety factors were 1.516 and 0.958 for winter and summer, respectively. Additionally, the slope failure may occur in summer. Implications: The research of seepage and stability in landfills may provide a less costly way to reduce accidents. Landslides often occur in the Jiangcungou Landfill because of the high leachate level. Some measures should be implemented to reduce the leachate level. This paper investigated seepage and slope stability of landfills by numerical methods. These results may provide the basis for increasing stability of landfills. [ABSTRACT FROM AUTHOR]

Chemical and physical clogging frequently occur in tailings dam. The clogging seriously influences the safety of tailings dam. This paper conducts several column experiments to analyse the physical and chemical clogging of the Lixi tailings dam in China. The experiment results of chemical clogging show that average flow velocity and permeability decrease by approximately 50% to 60%. The experiment results of physical clogging show that these values decrease by approximately 50% to 70%. For physical clogging, a higher hydraulic gradient could result in a larger extent of decrease in the permeability coefficient. The permeability did not decrease when the hydraulic gradient was equal to 0.125. The results of chemical clogging column experiments show that ferrous ion solution concentration is disproportional to the permeability coefficient. This scenario can be attributed to the extremely small concentration gradients. [ABSTRACT FROM AUTHOR]

Abstract: Endogenous reactive oxygen species (ROS) control is important for the maintenance of self-renewal of embryonic stem (ES) cells. Although miRNAs have been found to be critically involved in the regulation of the self-renewal, whether miRNAs can regulate the signaling axis to control ROS in ES cells is unclear. Here we show that miR-29b specifically regulates the self-renewal of mouse ES cells in response to ROS generated by antioxidant-free culture. Sirt1 is the direct target of miR-29b and can also make mES cells sensitive to ROS and regulate the self-renewal of mES cells during the response of ROS. We further found that Sirt1 could attenuate the miR-29b function in regulating mES cells' self-renewal in response to ROS. Our results determined that miR-29b–Sirt1 axis regulates self-renewal of mES cells in response to ROS. [Copyright &y& Elsevier]

Abstract: Epidemiological studies have demonstrated a close correlation between nickel exposure and the incidence of lung cancer. Several studies have suggested that nickel contributes to tumor progression of human lung cancer. In this in vitro study, we found that nickel, as nickel chloride, could significantly enhance the invasive potential of human lung cancer cells, accompanied by elevated expression of IL-8, TGF-β, MMP2 and MMP9 in human lung cancer cells. Importantly, we demonstrated that nickel could activate TLR4 signaling in human lung cancer cells. Further studies showed that the TLR4/MyD88 signaling conferred the enhanced invasive potential of human lung cancer cells induced by nickel. Finally, we revealed that the p38MAPK pathway and NF-kB pathway were necessary for the enhanced invasive potential of human lung cancer cells induced by nickel. Our data provide a mechanistic explanation for nickel induced invasion of human lung cancer, and they suggest new strategies for nickel-related lung cancer clinical biotherapies. [Copyright &y& Elsevier]

• High temperature reduces the adhesion between asphalt and concrete. • As the new bond is generated, the adhesion of asphaltene-phenol is the strongest. • Aging reduces the adhesion of molecules and has more impact at high temperatures. In this paper, reactive molecular dynamics is used to investigate the adhesion between asphalt molecules and aggregates, and explore the mechanism of action between asphalt and aggregates. Different asphalt molecules, system temperatures and aging of asphalt are considered. Through numerical simulation, it was found that there are physical (van der Waals force) and chemical interactions between the aggregates and the asphaltene molecules containing hydrogen atoms. The new bond is generated through the chemical reaction, which provides strong bonding force to enhance the adhesion of the interface. Other types of molecules and aggregates are only combined through physical attraction, and the bonding force is weak. In addition, the aging of the asphalt causes the loss of hydrogen atoms, so the adhesion between the asphalt and the aggregate is weakened. In summary, numerical simulation results provided a reference for the research and production of asphalt materials with better adhesion properties. [ABSTRACT FROM AUTHOR]

Historically, seepage failure has always been the primary cause of failures and accidents of earth dams after overtopping. However, research on the reliability of earth dams against seepage failure remains scarce. Meanwhile, the influence of the uncertainty of the soil–water characteristic curve (SWCC) on the reliability of dams against seepage failure is still unclear. In this study, the van Genuchten–Mualem model is used to describe SWCC, and its uncertainty is characterized by discretizing SWCC fitting parameters a and n into cross-correlation lognormal random fields. Based on the random finite element method, this paper systematically studies the influence of the heterogeneity, autocorrelation, and cross-correlation of hydraulic parameters Ks, a, and n on the reliability of a dam against seepage failure. Sensitivity analysis indicates that Ks and autocorrelation distance crucially affect the reliability of the dam against seepage failure. Additionally, this paper also emphasizes and proves that considering the correlation between the hydraulic conductivity field and the critical hydraulic gradient field has a significant impact on evaluating the reliability of earth dams against seepage failure. However, this subtle but important potential characteristic has not been paid attention to in previous studies. [ABSTRACT FROM AUTHOR]

• Compare influence zone of cavern and drainage system with influence radius of well. • Statistical analyse the characteristics of 56 operational pumped storages. • Study the influence mechanism of model range on seepage analysis results. • Proposed the influence zone determination method for cavern and drainage system. The construction and operation of underground cavern and drainage system for pumped storage are threatened by groundwater seepage. Numerical simulation methods are commonly used for seepage analysis of cavern and drainage system. However, the method for determining the influence zone of the cavern and drainage system is unclear. The model range is difficult to confirm, and the accuracy of the analysis results is unwarranted. In this study, the engineering and geological characteristics of 56 operational pumped storages were summarised. Numerical simulation experiments were conducted based on steady seepage analysis of simplified pumped storage with cavern and drainage system. The influences of the model range on the groundwater level and flow rate of the cavern and drainage system were investigated, and a method for determining the influence zone was proposed for the cavern and drainage system. The results indicated that unclear influence zone of the cavern and drainage system existed in numerous pumped storages. Moreover, a small model range strongly overstated the results regarding the flow rate and groundwater level, as the groundwater drawdown at the computation boundary was ignored. Increased influence factors, including the right and left bank groundwater surface slope ratio, maximum water head depth above the cavern, and volume of the cavern, delayed the stable tendencies of the changes of the flow rate and groundwater level with an increased model range. With a receivable flow rate threshold, the proposed method could be used to predict the influence zone for the cavern and drainage system, and the optimal model range could be confirmed to improve the calculation accuracy of seepage analysis. [ABSTRACT FROM AUTHOR]

Xu, Z.; Wang, X., and Chai, J., 2020. Piping particle movement using a seepage test based on NMR technology. In: Hu, C. and Cai, M. (eds.), Geo-informatics and Oceanography. Journal of Coastal Research, Special Issue No. 105, pp. 12–17. Coconut Creek (Florida), ISSN 0749-0208. As a kind of seepage failure mode occurred in hydraulic earth structures (dikes, levies, or dams), piping could cause dam-break in earth-rock dams. Additionally, although many investigators have applied many experiments to study the mechanism of piping, the initiation and development mechanism of piping is still poorly understood. In this study, a vertical piping test was conducted on stained noncohesive soil by an experimental device to measure a serial of parameters (the critical hydraulic gradient, porosity, upper particle size of lost particles, and accumulated sediment) in the development of piping phases. The particle migration pattern and change of porosity were then observed by the nuclear magnetic resonance (NMR) technology. The results show that the phases of piping are controlled by the content of movable particles and the particle size distribution curve. Three migration types of particles can be distinguished by NMR results and stained noncohesive soil during the piping phase. On basis of the empirical formula between hydraulic gradient and flow rate, if it shows a liner that means the soil is still well graded during the piping; if it divides into two separate lines that means the soil is unstable in the range covered by the second line. Additionally, the critical hydraulic gradient is located around the lines' connection points. [ABSTRACT FROM AUTHOR]

Finite element method (FEM) is usually used in dam and large underground cavern engineering to evaluate complex anti-seepage and drainage systems. In general, the substructure method is used to simulate the drainage hole array, but it becomes cumbersome when the number of drainage holes is large and the model is more complicated. In this study, the drainage holes were simplified and simulated as a line. The calculation results of the proposed method were then compared with those of the substructure simulation method and the well flow formula. This method has approximate accuracy, and it is easier to model with fewer nodes and elements compared with the substructure method. Based on the data of Heihe Reservoir, a three-dimensional equivalent continuum seepage FEM, reflecting the topography and geology of the dam area, was established, along with engineering layout and anti-seepage drainage system. The seepage field of nine different anti-seepage and drainage facilities were studied. The effects of drainage hole spacing and impervious curtain on seepage field were investigated. When the drainage holes were working normally and the drainage hole spacing was 2 m, the phreatic line in the dam body was the lowest and the drainage effect was the best. The analysis results showed that the failure of drainage holes on the left and right banks significantly influenced the seepage discharge of dam body and impervious curtain. According to the distribution of seepage field, a reasonable spacing of drainage holes is selected, and reasonable suggestions are put forward for anti-seepage and drainage in different parts. [ABSTRACT FROM AUTHOR]

• Coupled shear-flow tests with hydraulic pressure up to 0.8 MPa were conducted. • The influence of joint surface destruction and gouge material was discussed. • The anisotropy of flow regime caused by anisotropic joint surface was discussed. • Modify cubic law with hydraulic gradient, mechanical and hydraulic aperture. The single-fracture seepage model is important for fracture network seepage models and underground engineering, but the existing knowledge is insufficient for the roles of the high hydraulic pressure, joint surface destruction, gouge material, and the anisotropy of flow regime in the single-fracture seepage model during shear process. In this study, coupled shear-flow tests were conducted at 0.2, 0.4, 0.6 and 0.8 MPa hydraulic pressure with radial fluid flow, and then 3D simulation models were established by using COMSOL Multiphysics 5.2a with the Reynolds-averaged Navier–Stokes k- ε turbulence model for initial and peak shear conditions. Results showed that the radial flow cubic law diverged from experimental results seriously, and non-Darcy flow behaviour was remarkable during tests. High hydraulic pressure decreased the accuracy of the radial flow cubic law dramatically by increasing the influence of inertia force, and the accuracy was sensitive to the increase in lower hydraulic pressure. The flow regime and velocity were varied and influenced by the anisotropic tortuosity ratio, maximum inclination angle, and the uneven distribution of aperture. The absolute values of velocity vertical to the radial distance reduced with decreasing roughness. The roughness, tortuosity ratio, and maximum inclination angle of the fracture joint reduced dynamically with destruction of the joint surface and formation of gouge material, leading to a significant change in the relationship between mechanical and hydraulic apertures. Moreover, the radial flow cubic law was modified on the basis of the relationship of mechanical and hydraulic aperture with hydraulic gradient. This study may serve as a basis to establish fracture network seepage model and other similar tests. [ABSTRACT FROM AUTHOR]

To solve the problem of asphalt concrete panel cracking at low temperatures, this study proposes to use crumb rubber as a modified material for asphalt in the impermeable layer of asphalt concrete panels and to investigate the anti-cracking performance of crumb rubber modified asphalt concrete (CRMAC) in water conservancy projects in different low-temperature environments. Taking matrix asphalt concrete (MAC), CRMAC, and SBS modified asphalt concrete (SBSMAC) as the research objects, the cracking resistance performance of the three kinds of asphalt concrete under different low-temperature conditions were comparatively analyzed by using ultra-low-temperature (−35°C) small beam bending test, which reveals the damage mechanism of asphalt concrete's low-temperature cracking and damage process; the failure temperatures of the three kinds of asphalt concrete were accurately quantified by the thermal stress restrained specimen test (TSRST), and combined with the Pearson correlation coefficient method to determine the evaluation criteria of asphalt concrete low-temperature performance. The results show that the low-temperature crack resistance of CRMAC is better than the other two asphalt concretes under the same temperature conditions. Its failure temperature reaches −43°C, which meets the low-temperature demand for asphalt concrete panels in alpine regions. This study aims to improve the low-temperature cracking resistance of asphalt concrete impermeable panels, provide new ideas for the selection of asphalt concrete panels, and lay the foundation for the application of CRMA in water conservancy projects, and open up new ways to solve the problem of waste tire accumulation. • Proposed using CRMAC as impermeable layer materials for asphalt concrete panels. • Different types of asphalt: Karamay 70, SBS, and crumb rubber modified investigated. • Using TSRST to measure failure temperatures of asphalt concrete: CRMAC −43℃. • Small beam bending test temperature range: −35℃∼−10℃. • The cracking damage mechanism of asphalt concrete at low temperatures is revealed. [ABSTRACT FROM AUTHOR]

Concrete cut-off walls are a well-established technique for forming seepage cut-off in pervious and compressible foundations in newly constructed dams. This study investigated the behaviour of cut-off walls on the basis of statistical analysis. A set of monitoring records and construction details of 43 case histories of in-service concrete cut-off wall constructed in the past 50 years were gathered. Detailed statistical analyses of horizontal displacement, crest settlement, cracking behaviour and stress of the walls were performed based on the case histories. Loading characteristics and relative settlement between the wall and the alluvium foundation were analysed. The statistical analyses also attempted to identify quantitatively the major factors affecting the wall behaviour; these factors include wall location, wall material, foundation deformation characteristics, wall depth and valley shape. The wall location was found to be the deterministic factor that affects the wall behaviour. The findings and results of this study provide a significant insight into concrete cut-off wall behaviour and provide a valuable reference for future wall design and construction. [ABSTRACT FROM AUTHOR]

Longitudinal erosion is the main mechanism of the overtopping breaching of dams. Although this type of erosion has been studied by conducting flume model tests, there are no experimental studies on the longitudinal erosion of concrete-face sand-gravel dams (CFSGDs). In this study, flume model tests were conducted to analyze the overtopping breaching of a CFSGD. Based on monitoring data recorded by pore water pressure sensors, measuring rods, and high-definition cameras, the longitudinal erosion process of the CFSGD was analyzed, and the influence of joint water stop failure on the longitudinal erosion process was studied. The results showed that the scour pit and the central mound area were the most evident erosion characteristics, similar to that observed in an actual breaching process. A longitudinal evolution model was proposed, which reflects the erosion characteristics of the CFSGD at different stages. The longitudinal erosion rate and undercutting erosion rate were found to first increase and then decrease. The joint water stop failure did not change the longitudinal erosion characteristics; however, the seepage reduced the shear strength of the soil, and the dam breaching duration was 1.53 times that observed in the intact water stop case. Through a force analysis of the soil particles on the seepage surface, the critical angle (θcr) for erosion failure on the seepage surface was determined, and a formula for the critical shear stress (τc) of the soil particles under the action of seepage and overflow was derived. [ABSTRACT FROM AUTHOR]

This study evaluated the behaviour of a concrete face rockfill dam (CFRD) built on river gravel foundation on the basis of in-situ measurement records and numerical analysis. The monitoring records were obtained from a detailed deformation-monitoring system. A 3D finite element analysis was performed to assess long-term dam behaviour. The behaviour of the CFRD built on river gravel foundation was analysed comprehensively. A discussion of behaviour, especially with relevance to the behaviour of dams built on stiff-foundation, was included. The effect of the river gravel foundation was analysed, and the exact mechanisms were discussed. The relative contribution of various factors on the long-term behaviour of the CFRD was also studied. In-situ measurements were compared with numerical results to discuss the capability of the numerical model to predict the dam behaviour. [ABSTRACT FROM AUTHOR]

This study presents stability charts for estimating the stability of rock mass slopes that are suitable for the generalized Hoek-Brown (GHB) failure criterion based on the strength reduction technique. First, in order for implementing the GHB strength reduction, the estimation for the local Mohr-Coulomb (MC) friction angle and cohesive strength from the GHB criterion was incorporated into the strength reduction process in ABAQUS 6.10. Second, stability charts for calculating the FOS of rock slopes with a specific slope angle of β = 45° and D = 0 are proposed based on this method. Third, the disturbance weighting factors f D and slope angle weighting factor f β are used to quantify the effect of the rock mass disturbance factor and slope angle on the rock slope stability evaluations. Combined with the stability charts based on β = 45° and D = 0, the weighting factor f D and f β can be used to calculate the FOS of rock slopes with various slope angles under different blast damage and stress relief conditions. Finally, the stability charts were applied to two real case studies to illustrate the applicability and validity. The results for the two cases demonstrated good agreement with those from the other charts and the FEM software ABAQUS 6.10. The proposed charts provide a simple and straightforward way to estimate the FOS of the rock mass slopes directly from the GHB parameters. [ABSTRACT FROM AUTHOR]

This work studied the compressive behavior and microstructure of cement-based recycled concrete (CE-RC), low-volume fly ash (FA) recycled concrete (LFA-RC), and high-volume FA recycled concrete (HFA-RC) under different curing ages. The compressive properties, energy absorption properties, and microstructure of CE-RC, LFA-RC, and HFA-RC were measured and compared with cement-based normal concrete (CE-NC). The addition of coarse recycled concrete aggregate (CRCA) leads to more macropores and micro cracks in the concrete. As the result, the mechanical property of RC is worse than normal concrete. FA improved the energy absorption performance of recycled concrete in the early stage. With the continuous curing, pozzolanic reaction occurred between FA and the cement hydration product. The internal microstructure of LFA-RC and HFA-RC was improved. However, part of the FA in HFA-RC can only act as a filler and cannot fully participate in the secondary hydration reaction. Therefore, in the mature age, the internal pore distribution of LFA-RC was the most uniform. And the improvement of strength is more obvious. [ABSTRACT FROM AUTHOR]

This paper combined with the adaptive principle to improve the genetic algorithms (GA) and applied it to optimal design of the shape of the concrete face rock-fill dam (CFRD). Based on the improved GA, a mathematical model was established for the design optimization of CFRD. CFRD utilizes dam cost as objective function and dam slope and geometries of the dam material partition as design variables. Dam stability, stress, displacement, and stress level are used as the main condition constraints. The calculation procedures were prepared, and the GA was used to optimize the design of Jishixia CFRD. Results show that the GA could solve the global optimal solution problem of complex optimization design, such as the high degree of nonlinearity and the recessiveness of constraint conditions, and using the GA to optimize the CFRD design can reduce the quantities of projects and engineering safety costs. [ABSTRACT FROM AUTHOR]

Background: The amino acid transporter SLC6A14, which transports 18 of the 20 proteinogenic amino acids, is too low to be detected in healthy normal tissues but is significantly increased in some solid cancers. However, little is known about the roles of SLC6A14 in colorectal cancer (CRC).Methods: The mRNA and protein levels of SLC6A14 were detected using TCGA database, real-time polymerase chain reaction, western blot, and tissue microarrays, respectively. Amino acids concentration was determined by LC-MS/MS. Cell proliferation and apoptosis were determined using MTT assay and flow cytometry. Transwell invasion assay and wound healing assay were employed to analyze cell migration and invasion. The protein levels of Akt-mTOR signaling pathway and MMPs proteins were detected by western blot.Results: Both of the mRNA and protein levels of SLC6A14 were upregulated in CRC tissues, and the protein levels of SLC6A14 were closely related to the tumor cells differentiation: the higher the expression of SLC6A14 was, the poorer the differentiation of the tumor cells was. Further knockdown SLC6A14 with siRNA or treatment with α-MT in CRC cell lines reduced cell proliferation and migration in vitro and inhibited xenograft tumor growth in vivo. Mechanistically, SLC6A14 was demonstrated to regulate the expression and phosphorylation of Akt-mTOR, which mediates the promoting tumor growth function of SLC6A14. Blockade of SLC6A14 with α-MT inhibited the activation of mTOR signaling.Conclusion: SLC6A14 was upregulated in CRC and could promote tumor progression by activating the Akt-mTOR signaling pathway, which may serve as an effective molecular target for the treatment of CRC. [ABSTRACT FROM AUTHOR]

The combined influence of dip angle and adsorption heterogeneity on solute transport mechanisms in heterogeneous media can be understood by performing simulations of steady-state flow and transient transport in a heterogeneous aquifer with dipping anisotropy. Reactive and non-reactive contaminant transport in various types of heterogeneous aquifer is studied by simulations. The hydraulic conductivity ( K) of the heterogeneous aquifer is generated by HYDRO_GEN with a Gaussian correlation spectrum. By considering the heterogeneity of the adsorption distribution coefficient ( K), a perfect negative correlation between ln K and ln K is obtained by using the spherical grains model. The generated K and K are used as input to groundwater flow and transport models to investigate the effects of dipping sedimentary heterogeneity on contaminant plume evolution. Simulation results showed that the magnitude of the dip angle strongly controls the plume evolution in the studied anisotropic and heterogeneous aquifer. The retarded average pore-water velocity ( v/ R) of the adsorption model significantly controls the horizontal spreading of the plume. The bottom plume is intensively retarded in the zones between the dipping lenses of lower hydraulic conductivity and the no-flow bottom boundary. The implications of these findings are very important for the management of contaminated heterogeneous aquifers. [ABSTRACT FROM AUTHOR]

To study the shear properties and damage constitutive model of plain concrete (PC) and nylon fiber recycled from waste reinforced concrete (RNFRC), the direct shear test under different normal stresses (σ n , from 1 to 5 MPa) with a continuous horizontal rate of 0.5 mm/min is conducted on the cube specimens at different ages. The 3D roughness parameters of shear surface and the evolution of shear strength components are studied. Results show that the peak shear strength of RNFRC at 3, 7 and 28 d ranges from 6.65 to 12.09, 8.07–13.94 and 8.93–15.27 MPa under different σ n , exhibiting varying degrees of enhancement compared to those of PC. The values of the 3D roughness parameter C gradually increase while R s and the joint roughness coefficient (JRC) decrease with increasing σ n. The evolution of shear strength components is affected clearly by σ n. The calculation results of shear damage constitutive model match well with the experimental results. • The feasibility of using recycled nylon fibers to enhance the shear properties of concrete is discussed. • The roughness parameters of shear surface are analyzed by quantifying the 3D morphology characteristics. • The evolution shear strength components and their contribution to the peak under different test conditions are studied. • A new peak shear strength criterion based on the 3D morphology parameters and the damage constitutive model are proposed. [ABSTRACT FROM AUTHOR]

Thermal conductivity is an important parameter reflecting the heat transfer capacity of soil. In engineering applications, the thermal conductivity of soil varies with influencing factors such as particle size, porosity, water content, saturation, and seepage velocity of soil. At present, the thermal probe method and the traditional thermal response test method are mainly used to determine the thermal conductivity of soil. However, these methods can only perform point temperature measurements and require an inversion calculation based on a particular heat transfer model to obtain the value of soil thermal conductivity. Compared with this and other temperature monitoring methods, optical frequency domain reflectometry (OFDR) offers the advantages of distributed measurement, high measurement accuracy, high spatial resolution, and fast speed. In this paper, an OFDR-based measurement of soil thermal conductivity is designed. Taking sand as an example, the influence of different influencing factors on the measured value of thermal conductivity of soil was studied through the measurement test of thermal conductivity of soil, and the results are compared with the calculation results of the theoretical model of thermal conductivity and the results measured by the thermal probe method. The test results showed that when there was no seepage in the soil, the thermal conductivity of the soil exhibited an "S"-shaped growth trend with increasing water content; when the soil had seepage, the thermal conductivity of the soil was larger than that without seepage, and the thermal conductivity showed a positive linear increase with the increase in seepage velocity; With the increase of heating power, the measurement results tend to be stable. By comparing with the results obtained by other methods, the measurement results of the thermal conductivity measurement method proposed in this study have high accuracy. [ABSTRACT FROM AUTHOR]

There are many practical problems in the rapid development of the concrete face rockfill dam, which mainly focus on a large number of cracks and extrusion breakages in the face slab caused by temperature-induced stress, shrinkage stress, deformation of dam and other reasons, which eventually lead to leakage, threatening the safety of the dam. To solve this problem, the three-dimensional finite element analysis method is combined with the block equivalent continuum method to calculate the three-dimensional seepage field of the dam area, in order to study the seepage characteristics of numerous and unevenly distributed cracks in the concrete face rockfill dam; then, the corresponding head distribution and seepage characteristics, including the phreatic line, the hydraulic gradient and the seepage discharge, were obtained. The findings of this paper validate the accuracy and reliability of the block equivalent continuum method. It not only meets the requirements of simulation accuracy, but also can obtain the characteristics of the local seepage field near the crack. At the same time, it greatly simplifies the finite element model and significantly improves the efficiency of seepage calculation. This method provides a reference for the seepage analysis of similar projects. [ABSTRACT FROM AUTHOR]

Abstract: The lower Liaohe River Plain (LRP) is an economically and ecologically important area situated on an alluvial plain, where anthropogenic activities are very intensive. Field investigations were conducted in the LRP and 15 water quality parameters surveyed at 216 wells during September and October of 2009 and 2010. These showed significant variation in the hydrochemistry of groundwater throughout the plain. A Piper plot was used to identify the major geochemical processes occurring in the entire plain. Principal components analysis (PCA) was used to identify various underlying natural and anthropogenic processes that created these distinct water types. The Stuyfzand classification was used to subdivide and interpret the complex groundwater hydrochemistry of the Liaohe River delta. Five principal components (PCs) were extracted in terms of PCA, which can be invoked to explain 82% of the total variance in water quality parameters. The PCA results can be categorized by five major factors: (1) Holocene transgression and mixing; (2) surface water infiltration; (3) multi-factor processes; (4) rainfall and agricultural fertilizer contamination; and (5) Geogenic F enrichment. This study demonstrates that the great variation of groundwater hydrochemistry in the LRP should be attributed to both natural and anthropogenic processes. [Copyright &y& Elsevier]

Abstract: The LIM homeodomain transcription factor Islet1 (Isl1) is expressed in multiple organs and plays essential roles during embryogenesis. Isl1 is required for the survival and specification of spinal cord motor neurons. Due to early embryonic lethality and loss of motor neurons, the role of Isl1 in other aspects of motor neuron development remains unclear. In this study, we generated Isl1 mutant mouse lines expressing graded doses of Isl1. Our study has revealed essential roles of Isl1 in multiple aspects of motor neuron development, including motor neuron cell body localization, motor column formation and axon growth. In addition, Isl1 is required for survival of cranial ganglia neurons. [Copyright &y& Elsevier]

Concrete face rockfill dams are widely used in hydropower engineering because of their many advantages. As important structures, if the performance of the concrete face slab and the impervious curtain is weakened, leakages and even serious dam failures can occur. Based on an equivalent quasi-continuum medium model, three-dimensional finite-element numerical simulations of the seepage behaviour of Miaojiaba dam, China, are performed. The seepage field and seepage characteristics, including the phreatic line, maximum hydraulic gradient and seepage discharge, are analysed quantitatively and systematically under various abnormal conditions. The results show that cracks in different areas of the face slab and different degrees of degradation in the impervious curtain influence the seepage field in different ways, with cracks in the lower face slab being the most serious. Ensuring that the face slab and impervious curtain are working as intended is very important for the integrity of the dam. Therefore, the design and construction quality of impervious structures should be strictly controlled. Under abnormal conditions, seepage control should be realised to ensure the safety and stability of concrete face rockfill dams. [ABSTRACT FROM AUTHOR]

This study experimentally estimated the fractal pore size distribution of granites, which is then linked to the hydro-mechanical properties of rocks treated by temperatures that range from 25 ∘ C to 900 ∘ C. The mercury intrusion experiment was carried out to characterize the pore size distributions and the MTS815.02 triaxial testing system was used to investigate hydro-mechanical properties of rocks. Finally, the micro-CT scanning system and scanning electron microscope system were employed to exhibit the evolutions of microstructures of cracks that were then linked to the macroscopic hydro-mechanical properties. The results show that the pore size distribution of granites follows the fractal scaling law and the fractal dimension ranges from 2.45 to 2.94. The fractal dimension decreases significantly when the temperature increases from 25 ∘ C to 100 ∘ C and then holds a constant with continuously increasing the temperature to 400 ∘ C. The fractal dimension slightly increases as the temperature increases from 400 ∘ C to 500 ∘ C and decreases following a linear relationship until the temperature of 900 ∘ C. The porosity obtained by the mercury intrusion experiment shows an exponential relationship with the fractal dimension. Both the axial stain and peak total stain, as well as the initial permeability and the permeability at the peak axial stress, have quadratic functions with the fractal dimension. The mean aperture of fractures increases from 56.75 μ m to 76.10 μ m with increasing the temperature from 100 ∘ C to 900 ∘ C through micro-CT scanning. The scanning electron microscope test clearly shows that the fractures are generated when the temperature exceeds 300 ∘ C, which agrees well with the micro-CT scanning results. With increasing the temperature from 400 ∘ C to 900 ∘ C, both the number and aperture of fractures increase, which well interprets that both the strain and permeability increase as indicated by the triaxial stress-flow tests. [ABSTRACT FROM AUTHOR]

• The incorporation of CF and CNTs will reduce the real w/c-ratio, deteriorate the fluidity and delay the hydration process. • The volume change rate of capillary pores can reflect the hydration rate. • The thermal conductivity of mortar with CB is the highest, and that of mortar with CF is the lowest. • A small amount of reinforcing phase affects the thermal conductivity mainly by changing its pore structure and hydration. • The small sample learning model demonstrates that a limited sample of experimental data can make reliable predictions. To reveal the impact of various sizes of inert reinforcement on the pore structure, hydration products, and microscopic morphology of mortar. To explore its effect on mortar's thermal conductivity. Investigated by microscopic tests and small sample regression modeling. It is found that nanoscale materials have a nanocore effect, which can effectively enhance hydration, but the filling and bridging of larger pores is inadequate, leading to lower thermal conductivity in the early stage. The release of their properties is limited by the dispersion technique. Micron-reinforcing-phase, easily dispersed and with adsorption, can effectively fill capillary pores, and adsorb the hydration products to advance the hydration process. Milli-reinforcing-phase, flocculent fiber water absorption is obvious, resulting in the reduction of the real water-cement ratio, hydration process is delayed. With age growth and water precipitation, the fiber surface produces nucleation sites, which will accelerate the hydration rate. For thermal conductivity, porosity is the main influence factor in the early curing stage; when the porosity changes are small, the internal microstructure and hydration products will become the dominant factors. The sample set is expanded by feature enhancement and data synthesis to improve the generalization ability. The predicted model R2 can reach 0.75, demonstrating that a limited sample of experimental data can make reliable predictions. [ABSTRACT FROM AUTHOR]

This paper develops a nonlinear shear-strength reduction technique for analyzing the stability of uniform slopes with the general nonlinear failure criterion. To incorporate the nonlinear power-law failure criterion into the finite-element slope stability analysis with the shear-strength reduction method (SSR-FEM), a general tangential approach is employed to obtain the instantaneous cohesive strength and internal friction angle from the power-law failure criterion iteratively. Therefore, the shear strength of the power-law criterion can be expressed by the instantaneous Mohr–Coulomb (MC) parameters related to stress within the slope soil. By this way, it is possible to use the linear MC failure criterion for the nonlinear slope stability analysis based on the conventional SSR-FEM. The proposed approach is applied to three typical examples including a homogenous 2D slope, a homogenous 3D slope, and a high rockfill embankment slope. The results show that the nonlinear shear-strength reduction technique presented in this paper can guarantee the accuracy and feasibility to determine the factor of safety (FOS) and provide an alternative way for stability analysis of simple uniform cohesive slopes with a general power-law criterion. [ABSTRACT FROM AUTHOR]

• The seepage analysis considers the water released by the MSW itself. • SWCC of the MSW in the Jiangcungou Landfill, Xi'an, China was tested. • Effects of landfill age and dry density on the SWCC parameters were analyzed. • Landfill lifecycle was simulated using unsaturated-saturated seepage theory. In this study, an analysis of municipal solid waste (MSW) is undertaken at the Jiangcungou landfill in Xi'an, China. Using waste specimens gathered from the landfill, the soil water characteristic curve (SWCC) is determined at the laboratory, and the effects of landfill age and dry density on the SWCC parameters are analyzed. Leachate level trends during the landfill lifecycle are examined by performing saturated-unsaturated seepage analysis with the consideration of precipitation, as well as the inner source of water. These results are then summarized into three primary points. First, the shallow waste in the Jiangcungou landfill lost its water relatively quickly at small negative pressure heads, while the deep waste lost its water much more gradually. In addition, the deeper waste exhibited a lower volumetric water content when the matrix suction was less than 1.4 kPa, but the result was opposite when the matrix suction was more than 2.0 kPa. Second, the saturated volumetric water content and steepness of the SWCC decreased as the dry density increased, and the residual volumetric water contents increased and the inverse of the air-entry pressure decreased with increasing landfill age. Third, layers three, five and six demonstrated the highest leachate levels in the eighth landfill stage especially layer five, and these merit the greatest attention in monitoring and construction. These findings may provide a basis for the management of the Jiangcungou landfill. [ABSTRACT FROM AUTHOR]

Ensuring adequate ventilation during tunnel construction is a critical issue that directly affects construction efficiency. A good ventilation environment can effectively guarantee the construction progress. In this paper, by repeatedly selecting the flow field simulation parameters and continuously summarizing the calculation methods, a reasonable model is selected to simulate the tunnel engineering. Specifically, the eddy current zone near the working face is obtained by analysing the flow field of forced ventilation tunnels. Furthermore, we analyse the dispersion and accumulation of harmful gases in the tunnel. The CO concentration at typical locations in the tunnel is also examined in order to determine areas with the lowest likelihood of harmful gas discharge. We then propose adding a jet fan to the tunnel to create an extraction plus ventilation tunnel. Simulation results reveal that the addition of a jet fan causes eddy currents that improve the extraction of harmful gases, thereby greatly reducing ventilation time and increasing efficiency. The results of the model can effectively guide the actual project, and help them save the construction time. [ABSTRACT FROM AUTHOR]

A simulation-optimization model (ADINA-MMRDE) has been developed using the commercial finite-element software ADINA coupled with an improved differential evolution algorithm (MMRDE) to estimate the hydraulic conductivity of the aquifer of the Lu Dila hydropower project in China. The ADINA-MMRDE model employed the sum of the weighted square difference between the simulated value and the observed value as the objective function. To evaluate the accuracy of the MMRDE, the ADINA software was also coupled with a classical differential evolution (DE) algorithm and particle swarm optimization (PSO). Before estimating the initial seepage field of the Lu Dila hydropower station, the performance of the ADINA-MMRDE model was first tested using a boundary-simplified model based on the initial seepage field model. The effects of different objective functions, measurement errors and population sizes on the performance of ADINA-MMRDE were investigated. Then the ADINA-MMRDE model was applied to the Lu Dila hydropower project by considering water levels in 20 boreholes. The results showed that the head calculated using the estimated parameters was very close to its observed value. The water levels of 13 monitoring boreholes were used for further confirmation of the parameters obtained by the inversion. The results revealed that the calculated values of the monitoring borehole water levels were generally well fitted to the measured values. This study demonstrated the effectiveness of the ADINA-MMRDE model for practical and complex parameter inversion tasks. [ABSTRACT FROM AUTHOR]

Seven volcanic rocks samples were collected from Southern Qinghai to analyze chemical speciation and migration behavior of heavy metals by sequential chemical extraction procedure and column leaching test. The geo-accumulation index, ecological risk index and the risk assessment code were applied to assess the heavy metal pollution and potential environmental effects in this area. Results revealed that the total concentrations of heavy metals did not exceed the background values in soil of this area. Most of the samples produced acid rock drainage. The order of heavy metal migration and transformation sequence in the volcanic rocks of Zhiduo region was Cd > Pb > As = Cu = Zn = Mn based on the geo-accumulation index and Cd caused heavy pollution, which was also confirmed by the leaching test. Moderate potential ecological risk posed by heavy metals occurred in the study area based on the potential ecological risk index. Cd contributed to most of ecological risk while the remaining heavy metals (except As) exerted medium to high risks to the environment according to the risk assessment code evaluation results. In summary, volcanic rocks possessed potential risks to the surroundings due to potential release of heavy metals. Cd that caused the pollution should be paid special attention. [ABSTRACT FROM AUTHOR]

Highlights • Waste polypropylene fiber fabric added to concrete is considered. • The compressive behavior and destruction characteristics of polypropylene-fiber-fabric-reinforced concrete are studied. • Results are compared with those of plain concrete and polypropylene-fiber-reinforced concrete. Abstract Waste fiber fabric has already become an important pollutant source of the world's environmental problems. If this waste was added into concrete, could the resulting composite concrete material be good enough for engineering use? This study is focused a feasibility study of the addition of polypropylene fiber fabric into concrete, as well as analysis of its compression property, damage evolution rule, and damage performance in macroscopic and microscopic fields. Concrete specimens were made from polypropylene spun-bonded materials produced from used clothes. Their compressive behavior, energy absorption characteristics, and destruction characteristics were compared with plain concrete (PC) and polypropylene-fiber-reinforced concrete (PPFRC). The result indicate that the addition of waste fiber fabric can improve the compression performance of concrete. The addition of waste fiber fabric materials to concrete is a technology that can be constantly improved, considering changes in both technical and environmental conditions. [ABSTRACT FROM AUTHOR]

• A quasi-distributed fiber optic monitoring system was constructed. • The rationality of centrifugal model test of faced rockfill dams was confirmed. • The additional tensile stress is easily generated at the bottom of the face slab due to the effect of water load. • The necessity of avoiding boundary effect in centrifugal model test was demonstrated. • The feasibility and accuracy of fiber Bragg grating sensing technology for deformation monitoring in centrifugal model tests of concrete faced rockfill dams was explored. The traditional method of tracking the deformation of centrifugal dam model involves burying marker points on the sidewalls, which is commonly used. However, the method is inaccurate in monitoring the deformation of the model since the constraining effect of boundary effect on the model. In this study, a quasi-distributed fiber optic monitoring system was constructed using fixed-point distributed fiber Bragg grating. Particle image velocimetry, earth pressure cell, and other electromagnetic sensors were combined to examine the rationality of the face rockfill dams centrifugal model tests. Through comparative analysis, the applicability and stability of the fixed-point distributed FBG technique in the centrifugal model test were demonstrated. It is also demonstrated that traditional monitoring methods will underestimate the deformation of face rockfill dams by 2.32 % ∼ 13.55 %. This study addresses the shortcomings of existing monitoring methods with excessive measurement errors and provides a more applicable monitoring tool for developing related experimental studies. [ABSTRACT FROM AUTHOR]

[Display omitted] • A comprehensive review of the effects of nanomaterials on the hydration progression of cement paste is presented. • The effect of chemical and physical dispersion of nanoparticles on the hydration reaction is discussed. • Propose the idea of relative hydration degree and discuss the evolution of each composite paste with the change of dosage. • Schematic diagram depicting the mechanism of the effect of each nanomaterial on the relative hydration degree. Nanotechnology has been widely utilized in the microscopic to macroscopic modification of building materials. The early hydration kinetics will have a significant impact on the characteristics of cement-based materials after consolidation. As a result, research into the early hydration mechanism of nano-reinforced phase composite cement pastes is necessary. The periods of hydration, as well as the composition and structural distribution of the hydration products, are all impacted differently by various types of nanomaterials. The relative hydration degree will be increased to a different extent. The microscopic mechanism of composite pastes' hydration kinetics is closely related to the special properties of nanomaterials. Effective dispersion is the key for nanomaterials to give full play to their properties. The dispersion technique also affects the hydration kinetics. Physical methods will improve the effective doping of nanomaterials and enhance the uniformity of distribution. The effect of chemical methods on the hydration reaction needs to be analyzed specifically according to its type and dosage. In this study, the mechanisms of hydration phenomena in composite pastes, the experiments related to hydration products, and the methods for quantifying the degree of hydration are integrated and discussed. The study aims to provide a comprehensive review of the important effects of the nano-reinforcing phases' specific properties, doping, and dispersion methods on early hydration kinetics. The significance is to provide a theoretical basis for applied research of nanotechnology to modify smart building materials. [ABSTRACT FROM AUTHOR]

Graphene-based membranes (GBM) will migrate in the soil and enter the groundwater system or plant roots, which will eventually pose potential risks to human beings. The migration mechanism of GBM depends on the interface behavior of complex soil components. Herein, we use molecular dynamics (MD) simulations to probe the interface behavior between GBM and three type minerals (quartz, calcite and kaolinite). Based on the investigation of binding energy, maximum pulling force and barrier energy, the order of the difficulty of GBM adsorption and desorption on the three minerals from small to large is roughly: quartz, calcite and kaolinite respectively. The graphene-oxide (GO), improves the binding energy and energy barrier, making GBM difficult to migrate in soil. Remarkably, a larger GBM sheet and high velocity external load improve GBM migration in soil to a certain extent. These investigations give the dynamic information on the GBM/mineral interaction and provide nanoscale insights into the migration mechanisms of GBM in soil. [Display omitted] • The migration mechanism of GBM in soil was analyzed by interface adsorption and desorption. • Molecular dynamics was applied to explore the interfacial behavior of nanomaterial/mineral. • Binding energy and energy barrier were obtained to reveal the migration mechanism. • Effects of functional groups, size and pulling velocity of GBM are elaborated. [ABSTRACT FROM AUTHOR]

In this paper, a penalty function method for solving non-linear optimization problems was introduced to obtain a reliability indicator and to calibrate the partial factors, avoiding the complexity associated with the calibration process of the partial factors and maintaining the accuracy of the reliability indicator. The proposed method was employed to calibrate the partial factors of gravity dam sliding stability analysis. The results indicate that using the penalty function-based calculation method to determine the reliability indicator not only ensures correctness and accuracy but also makes the calibration process of partial factors simple and easy to perform. [ABSTRACT FROM AUTHOR]

Background: The transcriptional regulator in embryonic development, KAP1, has been proved could promote cell proliferation and metastatic progression in a variety of human cancers. However, the role of KAP1 in hepatocellular carcinoma (HCC) remains unclear. The purpose of this study is to investigate the relationship of KAP1 expression with the progression and prognosis of HCC. Methods: We measured the expression level of KAP1 in both human hepatoma cell lines and HCC tissues obtained from HCC patients by real-time quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and western blot. Furthermore, the effect of KAP1 expression on hepatoma cell proliferation was investigated through KAP1 knock-down strategy. Besides that, the correlation between KAP1 expression and HCC progression was analyzed. Results: KAP1 overexpression was proved broadly existed in the human hepatoma cell lines. Furthermore, down-regulate the expression of KAP1 by specific siRNA could inhibit cell proliferation which was partly originated from the activation of p53 mediated signal pathway. Moreover, comparisons between the cancer tissues and noncancerous tissues proved the expression level of KAP1 was significant higher in tumor tissues obtained from HCC patients. In addition, KAP1 overexpression was significantly correlated with tumor size and tumor stage and also a predictor for poor prognosis of HCC patients. Conclusion: Our results presented here demonstrate that KAP1 plays an important role in HCC and could be regarded as a valuable biomarker for tumor diagnosis and prognosis prediction, as well as a potential target for the treatment of HCC. [ABSTRACT FROM AUTHOR]

Izbash's law, which has a simpler form and exhibits narrower variations of coefficients than Forchheimer's law, has been successfully used to describe nonlinear flow in rough fractures. However, the meaning of its coefficients and its relationship with Forchheimer's law are poorly understood. Based on mathematical derivations, we identified the relationship between the cubic law, Forchheimer's law, and Izbash's law. An improved, dimensionally consistent Izbash's law which can be treated as the modified cubic law was formulated by incorporating a correction coefficient m I. The value of this coefficient depends on fluid properties, fracture geometries, and flow rate, and can be used to estimate the nonlinear flow state at given flow rates, in a similar fashion to Forchheimer number (F 0). A critical m I value (m cri) of 1.1 was determined that indicates whether the nonlinear effect can be ignored. Because m I is flow-rate-dependent, it can serve to describe the local flow behaviors, whereas the Izbash's exponent m is generally treated as a constant. At the maximum flow rate for a given pressure gradient versus flow rate curve, the value of m is approximately equal to that of m I , indicating that m represents the maximum nonlinear deviation. To validate the improved Izbash's law and the relevant findings, results from four experimental studies were utilized, and numerical simulations were performed. The result of this validation suggests the rationality of the analysis. The multiscale roughness effects on the coefficients were also investigated by selecting two different sampling intervals to construct the fracture surface. It was demonstrated that secondary roughness can enhance the development of nonlinear flow and increase the value of m , while its effects are strongly dependent on internal geometrical properties. • Relationship between cubic law, Forchheimer's law, and Izbash's law is revealed. • An improved Izbash's law is proposed. • The critical value of m for characterizing the onset of nonlinear flow is 1.1 [ABSTRACT FROM AUTHOR]