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Explosive blasting in tunnel construction may provoke damage to the surrounding rocks, leading to economic and safety concerns. While studies on rock fragmentation mechanisms exist, the innovative mechanism of shaped charge hydrostatic blasting remains largely unexplored. This paper aims to fill this research gap by proposing the mechanical analysis model for shaped charge hydrostatic blasting. By integrating physical model tests with LS-DYNA numerical simulations, this study assesses the dynamic response and crack propagation behaviors of this blasting method compared to traditional shaped charge blasting. Further, this study delves into the effects of various charge structures on hole wall pressure and crack propagation characteristics in shaped charge hydrostatic blasting, finally determining the optimal charge structure. Findings reveal that the explosive stress of shaped charge hydraulic blasting persists over an extended period, effectively generating directional cracks. The water medium amplifies the near zone effect of blasting, curtails the disturbance in the far zone, augments the energy utilization rate of explosive, and enlarges both the crushing zone and the propagation of primary crack. The charge structure with water intervals at both ends of the energy accumulation device generally yields beneficial results, producing favorable directional cracks. However, the presence of water medium at the bottom of the blast hole impedes the rock fragmentation, it is advisable to increase the explosive quantity at this location.

Natural gas hydrates (NGH) stored in submarine deposits are a promising energy resource, Yet, the deterioration in sediment strength can trigger geological disasters due to drilling-induced hydrate dissociation. Hence, an in-depth investigation on geo physical-mechanical performance of gas hydrate-bearing sediments (GHBS) is crucial for recovery hydrates safely and efficiently. This paper provides a comprehensive assessment of the research progress on formation conditions, intrinsic properties, and mechanical responses of GHBS. The key findings have been presented: gas composition, inhibitors and promoters alter hydrate formation by modifying the thermodynamic equilibrium of temperature and pressure. Also, we identified the key determinants of porosity of GHBS and revealed the correlation between permeability, hydrate saturation, and hydrate morphology. Moreover, we highlighted the differences in mechanical behavior between hydrate-free sediments and GHBS along with their underlying mechanisms. Furthermore, we examined the methods for GHBS preparation as well as the employed test apparatuses, providing critical insights into the limitations and recommendations. By synthesizing data from existing literature, we conducted a comprehensive analysis of the dependence of mechanical parameters of GHBS on factors such as hydrate saturation, effective confining stress, and temperature, and discussed the mechanical responses subjected to various hydrate dissociation methods. Finally, we offer a perspective for future research to focus on the micro-scale aspects, heterogeneous distribution, and long-term stability of GHBS. The discerned patterns and mechanical mechanisms are expected to guide the improvement of predictive model for geo physical-mechanical behavior of GHBS and establish a reference for developing effective strategies for recovery hydrates.

This paper explores how participatory science helps address water supply challenges in developing countries suffering from water shortages. In the absence of technical capacity to monitor the water supply system, this participation constitutes an excellent alternative to involve citizens in data collection and evaluation of the quality of the water service. The paper presents the design and implementation of a participatory science platform that enables data about the quality of the water supply in the city of Kharas in Palestine to be collected. Thanks to significant citizen participation, the study demonstrates that participatory science enhances the management of the water supply system and public awareness and engagement. Temporal and spatial analysis of collected data helped us to better understand the water supply system and identify the causes of the water service degradation. The study shows that the success of citizen participation requires cooperation between the water staff and citizens, including continuous dialogue and training and the construction of a friendly citizen participation platform.

The excavation and unloading of silty mudstone slopes often precipitate slope instability and collapse. While abundant research addresses the macro deterioration of rock strength, the micro-damage mechanism of silty mudstone remains largely uncharted. To bridge this gap, our study innovatively utilized nano-materials to prepare silt-like mudstone subjected to the triaxial unloading test considering multiple paths. Then we delved into the variation in microstructure using Scanning Electron Microscopy (SEM), binarization, and fractal dimensions. Our findings reveal that: (1) The peak stress, residual stress, and residual strain of silt-like mudstone display a decreasing trend with an increase in initial deviatoric stress while the peak strain initially increases and subsequently decreases; (2) Following unloading, the crack propagation on fracture surface is dictated by both confining pressure and initial deviatoric stress, which profoundly impact porosity, particle fragmentation, and pore expansion; (3) As confining pressure and initial deviatoric stress elevate, the average morphology coefficient rises with a reduction in rate of change. The impact of unloading confining pressure on pore morphology diminishes; (4) The fractal dimension increases with increased confining pressure and initial deviatoric stress, with a transition in the pore surface from smooth to rough.

This study centers on the use of smart technology to improve the lifecycle management of underground facilities. It presents a comprehensive digital solution that addresses the challenges of underground facilities, particularly those related to the extensive use of underground space, as well as the requirements for safety, sustainability, and quality of services. The proposed solution emerged from discussions with experts, companies, and cities involved in the design, construction, and management of underground facilities. In this paper, we first discuss the major challenges of underground facilities, then, we present the development of a smart solution to address these challenges. This study demonstrates a promising perspective for the use of smart technology in the optimal management of underground facilities, and paves the way for its implementation.

The swelling deformation of expansive soil after immersion often lead to engineering disasters. In this paper, the experiments on the swelling properties of expansive soil in Hefei after microwave heating have been carried out. The results show that, the soil samples change from fine particles to coarse particles after microwave heating. With the increase of microwave heating time, the specific gravity of soil samples first increases and then decreases, while the liquid and plastic limit continue to decrease. In addition, microwave heating significantly affects the swelling behaviors of soil samples. With the increase of microwave heating time, both the free swelling ratio and vertical free swelling strain decrease. In the process of microwave heating, there are a series of physical and chemical changes in expansive soil, such as the water escaping from the interlayer structure of clay minerals, the transformation and decomposition of material components, which significantly changes the physical and mechanical properties of expansive soil.

To ensure the stability of the tunnel structure, this paper simulates the excavation process of shield tunneling in karst areas, and monitors the top of the arch, the bottom of the arch and the waist of the arch within the influence of the cave. It obtains the displacement and stress change laws under the influence of the upper cave and the lower cave. Finally, the main factors causing karst collapse in tunnels are explored through orthogonal tests. The results indicate that the displacement of the surrounding rock within the influence of the cave decreases and the stress increases. When the cavity and the tunnel reach the safety limit distance, the effect of the lower cavity on the stress around the tunnel is more obvious than that of the upper cavity. The results of the orthogonal test show that when the cavity is above the tunnel, the tunnel burial depth has the greatest influence on the stability of the surrounding rock; when the cavity is below the tunnel, the cavity height has the greatest influence on the stability of the surrounding rock.

To investigate the strength and failure characteristics of silty mudstone using different stress paths, silt-like mudstone specimens were subjected to triaxial unloading tests. The results indicate the following. (1) When subjected to equivalent initial deviator stress levels and differing confining pressures, the peak stress, residual stress, and elastic modulus, exhibited during unloading, increased concordantly with greater initial confining pressure. Both the peak strain and residual strain increased with rising initial confining pressure. The increase in peak strain and residual strain initially decelerated, then noticeably increased, before ultimately decreasing again. Additionally, the unloading failure time and strain rate demonstrated a negative correlation as the confining pressure increased. (2) Under different initial deviatoric stress conditions, the peak stress, residual stress, and residual strain, under unloading confining pressure conditions, decreased as the initial deviatoric stress levels elevated. Conversely, the peak strain and elastic modulus initially increased, then decreased under increasing initial deviatoric stress conditions. The unloading failure time and strain rate were both observed to decrease as the initial deviatoric stress levels increased. (3) Utilizing the Mohr stress circle enabled the characterization of the shear strength variation in the specimens during the unloading process. The cohesion and internal friction angle remained relatively consistent across the different unloading stress paths appraised, with cohesion being greater in path I versus path II, whereas the internal friction angle exhibited an inverse relationship. (4) The specimen failed during unloading due to lateral expansion caused by unloading confining pressure and collapse failure. The failure fracture surfaces predominantly manifested shear failure morphologies.

The initial dry density has a significant effect on the mechanical behavior of rockfill material (RFM). The size effects on the minimum/maximum dry density (referred to as dry density, ρd) of RFM still need further study. To investigate the relationship between ρd and dM, a series of surface vibration compaction tests and DEM simulations are performed on the samples with different maximum particle sizes dM. Both the physical and numerical results exhibit that ρd increases fast when dM ranges from 10 to 40 mm. When dM exceeds 40 mm, ρd increases slowly and tends to be a constant. Results indicate that ρd is affected by the gradation. To consider the gradation effect, a normalized parameter λ is introduced, and the relation between ρd and dM can be characterized by an empirical equation.

In this paper, a micromechanics-based constitutive representation of the deformation-induced phase transformation in polyethylene terephthalate is proposed and verified under biaxial loading paths. The model, formulated within the Eshelby inclusion theory and the micromechanics framework, considers the material system as a two-phase medium, in which the active interactions between the continuous amorphous phase and the discrete newly formed crystalline domains are explicitly considered. The Duvaut–Lions viscoplastic approach is employed in order to introduce the rate-dependency of the yielding behavior. The model parameters are identified from uniaxial data in terms of stress–strain curves and crystallization kinetics at two different strain rates and two different temperatures above glass transition temperature. Then, it is shown that the model predictions are in good agreement with available experimental results under equal biaxial and constant width conditions. The role of the crystallization on the intrinsic properties is emphasized thanks to the model considering the different loading parameters in terms of mechanical path, strain rate and temperature.

In order to realize the high efficiency quality classification and three-dimensional visualization of engineering rock mass and to solve the technical difficulties of the traditional rock mass quality evaluation method such as high labor intensity, long process time consumption, many intervention processes such as scale measurement and manual calculation, and nonintuitive classification results, this paper puts forward a 3D visual rock mass quality evaluation method and system based on close-range photography, which optimizes the traditional rock mass quality evaluation method, makes the rock mass classification three-dimensional and visible, and realizes the estimation of unrevealed rock mass quality evaluation index. The research results show the following: (1) The method of storing joint information by close-range photography and extracting joint information by human-computer interaction improves the working efficiency and the process is safe and controllable compared with the traditional method of collecting fracture parameters. (2) Based on the statistical analysis of 97 groups of roadway survey data, the comprehensive statistical regression formula between BQ value of Chinese national standard and RMR value is given, and there is a good correlation between BQ value and RMR value of rock mass quality index. (3) Based on the power-inverse ratio method, the three-dimensional model of rock mass classification of the mine was established, and the cutting model obtained the current distribution diagram of rock mass quality grade, providing scientific reference for drilling, blasting, support, and other production design optimizations.

The present paper presents analysis of the influence of the soil saturation on the free -field response of liquefiable soils. Analyses are conducted using a finite element program developed for partially saturated soils subjected to cyclic loading. The performances of the proposed model are analysed by simulation of undrained triaxial tests with different water saturations. The finite element program is then used for the analysis of the influences of the soil saturation, density and position of the water table on the liquefaction of a soil layer subjected to cyclic loading. Results show that the soil saturation significantly affects the liquefaction of partially saturated sandy layers. The decrease in the soil saturation results in a reduction of liquefaction risk. Keywords: Saturation, Free field, Liquefaction, Dynamic, Cyclic loading, Seismic, Numerical

The numerical modelling of the excavation of an underground gallery in hard clay has been discussed in current article. A constitutive model is proposed to describe poromechanical behaviour of the hard clay. The main features of the hard clay observed in laboratory and in-situ experimental investigation have been taken into account in the proposed constitutive model, in particular the plastic deformation, the visco-plastic deformation, the damage, etc. The influence of the initial in-situ stress and the pore pressure has been taken into consideration. The numerical modelling of the underground excavation has been implemented by using a fully coupled hydro-mechanical finite element calculation code. The performance of the model is examined by comparing numerical simulations with in situ measurements. The proposed model and the calculation procedure for the modelling of the excavation of an underground gallery have the capacity to reproduce well the excavation damaged/distributed zone and other main features and phenomena observed during the excavation process. However, the in-situ observed convergence could not be reproduced correctly. More effort on the discontinuous problem should be made for the reproduce the observed convergence. Keywords: Full coupled hydro-mechanical processes, Elasto-plastic-damage model, Visco-plastic model, Underground excavation

Completely disintegrated carbonaceous mudstone, a common embankment material, has significant swelling-shrinkage behavior under cyclic wetting and drying, which often causes the instability of embankments. In this paper, the evolution of the cracks in the completely disintegrated carbonaceous mudstone subjected to cyclic wetting and drying was studied by laboratory tests. The vacuum saturation method and the drying method based on heat lamps and a fan were employed to simulate the wetting and drying processes, respectively. The image processing technique was used to treat the images of the sample surface. Afterward, various geometric parameters of the cracks appeared on the sample surface were measured, and the evolution characteristics of the cracks were analyzed. The results show that with the increase in the number of wetting and drying cycles, the number of cracks on the sample surface gradually increases. After four wetting and drying cycles, the existing cracks produce a large number of small branches, which are connected to form irregular polygonal grids. The development of the cracks in the completely disintegrated carbonaceous mudstone sample can be divided into three stages, i.e., slow development, rapid development, and stable development. Both the surface density of crack and the crack rate first increase and then tend to be stable with the increasing number of wetting and drying cycles. New cracks are mainly generated on the basis of the existing cracks, and some cracks appear to heal under cyclic wetting and drying. The early cracks are mainly developed in the directions of 0°–90° and 300°–360°, and the development rate of the cracks in the directions of 30°, 90°, 140°–150°, and 180°–270° is significantly higher than that of the cracks in other directions.

This paper aims to assess groundwater potability and palatability in the West Bank, Palestine. It combines the adjusted weighted arithmetic water quality index method (AWAWQIM), a close-ended questionnaire, and step-wise assessment ratio analysis (SWARA) to develop groundwater potability (PoGWQI) and palatability (PaGWQI) indices. Both a geographic information system (GIS) and the kriging interpolation method (KIM) are employed to create spatiotemporal mapping of PoGWQI and PaGWQI. The research is based on data from 79 wells, which were provided by the Palestinian Water Authority (PWA). Data include fecal coliform (FC), nitrate (NO3), pH, chloride (Cl), sulfate (SO4), bicarbonate (HCO3), total dissolved solids (TDS), turbidity, and hardness. Results indicate that 2% and 5% of water samples were unpotable and unpalatable, respectively. Unpotable samples were found in areas with poor sewer networks and intensive use of agrochemicals. All groundwater samples (100%) in the eastern part of the West Bank were unpalatable because of seawater intrusion. Unconfined aquifers were more vulnerable to potability and palatability contamination. It was noticed that PoGWQI is sensitive to FC and NO3, while PaGWQI is sensitive to HCO3, TDS, and Cl. Consequently, these quality parameters should be monitored well. The proposed method is of great interest to water decision-makers in Palestine for establishing strategies to protect water resources.

This paper presents a smart solution for the utility tunnel, which allows hosting a wide range of water and energy utilities in an accessible underground space. It is well known that utility tunnels offer major advantages such as the possibility to inspect, maintain, and easily extend urban utilities without excavation, thereby eliminating disturbances related to urban excavation such as traffic jams, noise, pollution, and pavement degradation. However, despite these advantages, the effective development of this facility remains below expectations, because of serious challenges related to the security and governance of this “shared space”. The solution presented in this paper is based on discussions with experts and companies involved in the design, construction, and management of utility tunnels, as well as on the authors’ experiences in the design and implementation of smart solutions for urban utilities. The paper firstly presents the major challenges of utility tunnels and then discusses how theb smart technology could help in coping with these challenges. The paper presents the architecture of this solution, as well as the main layers of monitoring, information system data analysis, and system control. It also presents the methodology to be followed for the implementation of this smart solution. Finally, the paper discusses two major issues for utility tunnels: fire risk and risk assessment. The paper shows that the use of smart technology allows developing a comprehensive digital solution, which uses advanced monitoring system to collect real-time data about the tunnel environment and functioning. These data can be easily shared by authorized staffs. Analysis of these data allows improving the utility tunnel security and performances.

Time-dependent behavior of subcritical crack growth is one of the main characteristics in rocks. The double-torsion test is commonly used to study the slow crack growth behavior of brittle and quasi-brittle materials. However, double-torsion specimen is difficult to processing, the process of the laboratory test is irreversible, and the current numerical simulation is difficult to consider the time-dependent behavior, and so on. In view of all above problems, an idealized particle model was built, and the crack was identified in this article, based on the theory of particle flow. The numerical model was built using Particle Flow Code in 3 Dimensions, and the macromechanical and micromechanical parameters of the model were calibrated. The process of the macroscopic crack propagation and its evolution were analyzed. The intrinsic relations with the load, the displacement, and the time were established. The results show that the Particle Flow Code in 3 Dimensions can reproduce the time-dependent behavior of subcritical crack growth in double-torsion test. And, the peak and the law of the curves are in good agreement with the laboratory test results. Therefore, the Particle Flow Code in 3 Dimensions numerical simulation can be used as a new effective method to reveal the slow crack growth behavior, to get the relevant parameters such as V, K I , and K IC , and to build the relationship between V and K I . The results of this article will have some reference value for the simulation and application of double-torsion test.

According to the change characteristics of the subgrade moisture content and the mechanical calculation of several typical highways, the test scheme of the permanent deformation of coarse soil was formulated. The relationship between the permanent deformation of coarse-grained soil and the stress level, compaction degree, moisture content, and loading frequency was studied by cyclic loading triaxle testing. The results show that the permanent deformation of coarse-grained soil increases with the increase in partial stress and moisture content and decreases with the increase in compaction degree. The experimental data were fitted by the Tseng-Lytton model, and the correlation coefficients were 92%, which indicated that the model could be used to predict the permanent deformation of coarse soil. The relationships between the model coefficient and the moisture content and spring back modulus were obtained by the multiple regression method. Finally, the permanent deformation of the subgrade soil was calculated by using the layered summation method and a typical subgrade pavement structure.

The limitation associated with Fourier transform and wavelet analysis that they often fail to produce satisfactory resolution simultaneously in time and frequency when dealing with nonlinear and nonstationary signals is frequently encountered. Therefore, this paper aims at using the HHT (Hilbert–Huang transform) method, which is built on the basis of the EMD- (empirical mode decomposition-) based wavelet threshold denoising technique and the Hilbert transform, to analyze the blasting vibration signals in a south China lead-zinc mine. The analysis is conducted in terms of three-dimensional Hilbert spectrum, marginal spectrum, and instantaneous energy spectrum. The results indicate that the frequencies of the blasting vibration signals lie mainly within 0∼200 Hz, which consists of more than 90% of the total signal energy. At the onset of the blasting, the vibration frequency tends to be low, with the frequency that is less than 50 Hz being dominant. By using instantaneous energy spectrum, which can reveal the condition of energy release for detonator explosion, the initiation moments of detonators with 7 time-lag levels are accurately identified. This accurate identification demonstrates the superiority of the HHT method in coping with nonlinear and nonstationary signals. Additionally, the HHT method that is characterized by adaptivity, completeness, strong reconfigurability, and high accuracy provides an opportunity for reflecting signals’ change features with regard to time domain, frequency domain, and energy irrespective of the limitation of the Heisenberg uncertainty principle.

This paper presents an experimental investigation of the use of microwave irradiation to improve the characteristics of expansive soils. The expansive soil samples were subjected to microwave heating in an industrial microwave oven, and were followed by analysis of the soil characteristics such as the specific gravity, liquid and plastic limit, free swelling ratio, vertical free swelling strain and swelling pressure. X-ray diffraction was also used to determine the mineral composition of the samples. Experimental results showed that the microwave irradiation induces both a rapid increase in the soil temperature and a significant change in the soil mineral content. With the increase in the power level, we observed first an increase in the specific gravity up to a peak, which was followed by a decrease. For the other characteristics such as the liquid and plastic limit, the free swelling ratio, the vertical free swelling strain and the swelling pressure, their values were observed a decrease with the increase in the power level. The change in the soils characteristics could be attributed to the impact of the irradiation on the expulsion of the interlayer structure water and on the change of soil mineral content or structure. [ABSTRACT FROM AUTHOR]