Water Pressure Loading Research Articles

Structural analysis and optimal design of a spherical thin-walled stainless steel water tank without reinforced tie ribs

A spherical thin-walled stainless steel water tank without reinforced tie ribs has been designed to address the issues of easy fracture and corrosion of the ribs, difficulty in maintenance and cleaning, and short service life exposed during the use of thin-walled stainless steel water tanks with reinforced tie ribs. Firstly, an analytical model of a flat steel thin-walled water tank without reinforced tie ribs was established and subjected to static analysis under water pressure. The deformation and stress distribution patterns of the side molded plate of the flat box were obtained. Secondly, a spherical non ribbed thin-walled stainless steel water tank structure was designed with circular cross-section under different box bulge parameters, and its mechanical response characteristics under water pressure load were analyzed. A strengthening scheme was designed for the bottom box molded plate. Once again, optimize the combination design of the box scheme and the reinforcement scheme, and analyze their static, thermodynamic, and thermal solid coupling performance. Finally, the Latin Hypercube Sampling method was used to generate experimental design samples, and a response surface approximation model of a spherical thin-walled stainless steel water tank without reinforced tie ribs was constructed. The wall thickness of the box molded plate, skeleton, and reinforcement were used as design variables, and the maximum deformation and maximum equivalent stress were used as constraints. The lightweight design was carried out with the goal of minimizing mass. The research results indicate that the design program and parameter selection method for spherical thin-walled stainless steel water tanks without reinforced tie ribs proposed in the article are efficient and feasible, and can provide technical reference and theoretical support for the layout and overall optimization design of non ribbed thin-walled stainless steel water tank structures.

The influence of plating with flat bars around technological cutouts on the stress state of a 37500 tdw chemical tanker

The purpose of this study is to determine the stress states of the plating around the technological cutouts of a 37500 tdw chemical tanker under normal operational conditions, taking into account the efficiency of operational optimization and structural strength increase. This study will assess the stress state in the double bottom region of the ship, which experiences the most significant external loads from hydrostatic water pressure and internal loads from cargo pressure.

Experimental study on the high water pressure erosion mechanism and its influence on the submarine shield tunnel concrete segments

This study investigated a high water pressure erosion mechanism and its influence on the mechanical performance deterioration of submarine shield tunnel concrete segments using a series of tests. First, a chloride ion pressure penetration test was conducted to reveal the impermeability performance and chloride ion permeability of the tunnel lining concrete. Then, given the environmental and mechanical characteristics of the lining segment structure of a submarine shield tunnel, a cofferdam-type electrochemically accelerated corrosion method was proposed to simulate the simultaneous application of unilateral water pressure and compression-bending loads on the segment. The effects of water pressure on the strain, deformation, crack propagation, and failure mode of the segment components were investigated. In addition, the damage caused by high water pressure on the segment components was explored using acoustic emission. This study lays the foundation for further research on the durability of shield tunnel structures under high water pressures.

Mechanical and seepage characteristics of polyvinyl alcohol fiber concrete under stress-seepage coupling

This study presents an experimental investigation of the coupled stress and seepage water pressure loading test conducted on polyvinyl alcohol (PVA) fiber concrete, which had undergone salt attack freeze-thaw (F-T) cycles. This study delves into the influence of the number of salt attack F-T cycles, as well as the magnitude of seepage water pressure, on the triaxial compression seepage mechanical properties and permeability evolution of the specimens. Additionally, the nuclear magnetic resonance (NMR), scanning electron microscope (SEM) and X-ray diffraction (XRD) test results were analyzed, revealing that sodium sulfate solution penetrates the interior of PVA fiber concrete and reacts with cement stone to form ettringite and gypsum, which initially fills and compacts the pore structure. The increased production of such compounds causes pore structure to expand, with the maximum number of mesopores and macropores increasing by 115.5%. Macroscopically, it was observed that the mass and peak strength of the specimens increased at the beginning of the cycle, and the initial permeability decreased. However, the opposite phenomenon occurred after 15 cycles. When seepage water pressure was increased from 1 MPa to 3 MPa, the crack initiation stress, crack damage stress, and peak stress of the specimens decreased by 13.1%, 16.9%, and 15.6% on average, respectively, and the initial permeability increased by 69.3% on average. The deformation process of PVA fiber concrete under stress-seepage coupling loading was divided into five stages, including the initial compaction stage, elastic deformation stage, crack initiation and stable propagation stage, crack unstable propagation stage, and post-peak deformation stage. Correspondingly, the permeability exhibited a rapid decline, followed by a relatively stable phase, a slow rise, a rapid rise, and a continuous increase. Besides, the relationship between permeability and volume strain in compression and expansion stages was clarified.

Study on the Performance of Polyurea Anti-Seepage Spray Coating for Hydraulic Structures

The surfaces of hydraulic structures are vulnerable to damage and cracking, which can result in high-pressure reservoir water entering cracks and endangering the safety of the structures. Therefore, it is necessary to strengthen the anti-seepage treatment and protection on the surfaces of the structures. In this paper, we explore the tensile and high-water-pressure breakdown resistance properties of polyurea coating material. To do so, we independently designed and manufactured a high-water-pressure breakdown test device for coating. Our experimental results indicated that the thickness of the polyurea coating decreased with an increase in elongation. Furthermore, we found that the breakdown resistance of the polyurea coating was related to the coating thickness and the bottom free section width. We then fitted the stress–strain curve obtained from the experimental test using the Ogden constitutive model. Based on this, we numerically simulated the high-water-pressure breakdown performance of the polyurea coating using the finite element software ABAQUS 2022. We obtained the relationships among maximum displacement, free section width, and coating thickness under high water pressure. Our numerical findings indicated that the vertical displacement of the midpoint increased linearly with width in the case of the same coating thickness under water pressure load. Conversely, for the same free section width, the vertical displacement decreased with increasing coating thickness.

Simulation of internal water pressure loads for HPP penstock pipes under seismic impacts

Simulation of internal water pressure loads for HPP penstock pipes under seismic impacts

Numerical Analysis of Flow-Induced Vibration of Deep-Hole Plane Steel Gate in Partial Opening Operation

Hydraulic steel gates are the core adjustment mechanism for water conservancy projects, the safety of which is related to the safety of the entire water conservancy project. In this study, the issue of flow-induced vibration under the influence of pulsing water pressure when the deep-hole plane steel gate construction is partially opened is investigated using a numerical calculation approach of CFD–CSD coupling. The time-history pulsating pressure loads of each part are first determined by tracking the upstream, bottom, and downstream pulsating water pressure loads under partially open operation conditions of the gate. The impact of the water in front of the gate on the natural vibration mode and frequency of the gate is then investigated based on the analysis of the dry/wet modes of the gate structure. Additionally, the hydrodynamic load is applied to the finite element model of the gate structure while taking into account the fluid–structure coupling effect, and the results of the gate flow-induced vibration response are obtained. Three typical local opening relative openings are chosen, with the operating state of the design water head (Hs = 70 m) of a deep-hole plane steel gate as an example. According to the analysis’s findings, the gate’s natural vibration frequency is greatly lowered under the influence of the water in front of it, and its amplitude increases by 50%. The pressure value pressing on the gate changes dynamically as it is partially opened and discharged. The maximum dynamic displacement value and the maximum dynamic stress value of the gate both appear in the middle and lower part of the gate under the condition of partial opening, and both occur when the relative opening is e/H = 0.125. The maximum displacement value is 3.43 mm, and the maximum stress value is 161 MPa. The maximum dynamic displacement and dynamic stress of each gate component steadily decrease with an increase in the relative openness. The gate dynamic response analysis approach described in this research can serve as a guide for hydraulic engineering design.

A hydrostatic test study on the waterproofing of an underground ecological granary using a plastic-concrete system

Underground granaries can store grains at low and quasi-low temperatures due to the existing shallow geothermal energy, which can ensure long-term quality and grain preservation. However, water and moisture resistance of groundwater is a key technical problem which restricts its wide application. Consequently, a polypropylene plastic-concrete wall was proposed in this study to solve these problems. First, a hydraulic test was performed on three plastic-concrete specimens using polypropylene plastic (PP) plates of different thicknesses including 10, 15, and 20 mm to investigate the mechanical performance under water pressure loading. The displacement, deformation, interior force, failure mode, and mechanism of the plastic-concrete specimens were comprehensively analysed. Second, a lining waterproof component model was established based on the ABAQUS software. Finally, the interior force adjustment coefficient calculation formulas and interior force analysis method are presented according to the experimental results and direct design method for column-supported slabs. Consequently, the ultimate bearing capacities of the specimens with different PP plate thicknesses were 120, 180, and 170 kPa, respectively, and the failure modes of the specimens varied with the thickness of the PP plate. Moreover, for thicknesses greater than 15 mm, the ultimate bearing capacity of the specimen was mainly dependent on the strength of the nodes. The numerical simulation results correlated with the experimental data, where the stress and displacement of the plastic waterproof components increased gradually with increasing water pressure. The experimental and simulation results of this study can provide a reference for the waterproof design of underground granaries and widen their practical applications.

Modeling of the bubble collapse with water jets and pressure loads using a geometrical volume of fluid based simulation method

The dynamic behavior of bubble collapses, water jets, and pressure loads during the collapse of the bubble near walls and a free surface were numerically investigated via a geometrical volume of fluid (VOF)-based simulation method. The numerical method is based on the compressible Navier–Stokes equations in a conservative form that describe the flow of compressible viscous fluids. The equations are discretized on a general curvilinear grid using an associated Godunov-type numerical scheme, and a reconstruction of a computational finite-volume Riemann solver is introduced for suppression of oscillation near the interface between fluids. The interface was tracked using the VOF reconstruction method. The VOF method is based on a geometrical tool and Lagrangian propagation of the interface reconstructed by a piecewise linear interface calculation (PLIC), resulting in strictly mass-conserving and sharp interface solutions. The numerical procedure was validated for capturing sharp interface and strong shock waves. For the simulation of bubble collapse, grid dependence studies of a spark-generated bubble were studies of both spherical and non-spherical bubbles were conducted. The results showed good agreement between the simulation and experiment of the bubble dynamics during the collapse process. Subsequently, an investigation of a single bubble near a wall with different standoff distances was performed. The pressure loads induced by the jets impacting the walls were calculated and analyzed. Furthermore, a more complex case of bubble collapse near an oblique wall and free surface was simulated. The resulting bubble dynamics with the jets and free surface shape were compared via photographs of the experiments.

An Analysis of Slope Stability Based on Finite Element Method and Distinct Element Method

The analysis of slope stability involves complex geological and topographical boundary conditions, nonlinear behavior of material stress-strain, coupling analysis of initial in-situ stress, water pressure and seismic load, etc., and in most cases, analytical solutions cannot be obtained. Under the background of the continuous development of computer and calculation method, the numerical analysis method represented by finite element has been gradually popularized and applied in geotechnical engineering in 1970s, and has developed into a powerful calculation and analysis tool. Among them, the finite element strength reduction method and the discrete element method are the two most widely used slope numerical analysis methods. In this paper, two typical cases, Ankang reservoir landslide and Wenma Highway slope, are simulated by the two methods.Taking Ankang reservoir landslide as the research object, this paper would use MIDAS / GTS finite element analysis software, and two-dimensional finite element numerical simulation would be carried out to study the influence of reservoir water level periodic fluctuation on the reinforcement effect of anti-slide pile. Under the condition of water saturation and water loss cycle, main material of landslide body and landslide belt, namely the strong weathered phyllite, displays obvious deterioration phenomenon, showing the trend of rapid decline first and then slow decline; after the anti-slide pile is set in the middle and front of the slope, the stability of it has been greatly improved, but with the increasement of the number of water level changes, the reinforcement effect of the anti-slide pile continues to weaken, and the weakening speed is fast at first, and then slows down.Taking the bedding slope of Wenma Highway as the research object, this pater would adopt UDEC discrete element software to simulate the deformation and failure process of the slope after excavated, and analysize the failure mechanism at the same time. The failure process of bedding slope can be divided into four stages: the formation of tension cracks caused by excavation, the expansion of cracks and the formation of deformation body, the sliding of deformation body and the accumulation of damaged rock mass at the foot of slope. Tensile failure is the main failure mode, and shear failure occurs locally. The failure of bedding slope starts from the foot of slope, which is traction sliding.

Study on the Creep Damage Characteristics of Shale under the Combined Action of Osmotic Pressure and Disturbance Load

In the in situ modified fluidized mining engineering, the surrounding rock of the shaft wall is prone to creep instability damage under the action of disturbance and seepage water pressure, which seriously affects the stability of the surrounding rock of the deep in situ modified fluidized mining. In order to study the nonlinear creep damage and fracture characteristics of deep rocks under the combined action of seepage water pressure and disturbance load, a self-developed rock perturbation creep test rig under the action of seepage water pressure was used, and shale was used as the rock sample. In the method of staged loading, the rock uniaxial compression perturbation creep test under static axial pressure, different perturbation frequencies, and different seepage water pressures was carried out, and the creep characteristics of shale under the combined action of perturbation and seepage were studied. The results show that with the increase of seepage water pressure, the creep failure time of the rock decreases, and the ultimate strain value increases; with the increase of the disturbance frequency, the creep failure mode of the rock gradually transitions from shear failure to tension failure. When water pressure and disturbance load exist at the same time, rock creep is more sensitive to seepage water pressure; based on experimental results, a shale perturbation creep damage model considering the influence of seepage water pressure and disturbance frequency is established, and the model is verified. The research results have important theoretical significance for guiding the wellbore stability control of in situ modified fluidized mining engineering.

A wing-crack extension model for tensile response of saturated rocks under coupled static-dynamic loading

Saturated rocks, widely existing in various deep underground engineering, are likely to be encountered coupled static-dynamic loading. It is thus vital to acquire the combined effect of water saturation and static pre-tension on the dynamic tensile strength, and establish a reasonable crack extension model for describing the fracturing mechanism of saturated rocks under coupled static-dynamic tension. In this study, from the perspective of meso-mechanics, the relationship between pore water pressure and static pre-tension loading are first deduced, and then the analytic solution of stress field of elliptical crack orifice under coupled pore water pressure and far-field stress is solved using complex function. The effect of pore water pressure is considered into Griffith theory, and the most dangerous fracture azimuth angle of elliptical crack in rocks under combined far-field stress and pore water pressure are determined. Second, the length of fracture process zone of initial crack in saturated rocks under static pre-loading is estimated based on Schmidt's maximum tensile stress criterion. Finally, a wing-crack extension model is proposed to analyze the dynamic fracturing behavior of saturated rocks under pre-tension, and the theoretical calculation formula for tensile strength of saturated rocks under combined static-dynamic loading is obtained. To validate this new model, nine coupled static-dynamic tension tests with different pre-static loading ratio are performed on saturated flattened Brazilian disc (FBD) specimens, in virtue of the split Hopkinson pressure bar (SHPB) specialized with an axial confining apparatus. A rational consistency is observed between the experimental and theoretical results in terms of the dynamic tensile strength of saturated rocks.

Study on the Deformation Characteristics of Fractured Basalt Under Coupling of Three-Dimensional Stress and Water Pressure Cycling

The seepage-stress coupling of fractured rock masses is a physical, chemical and mechanical process that depends strongly on the lithological conditions, structural state, initial stress level and stress path for the hydraulic coupling during water storage. A newly developed true triaxial hydraulic coupling test system named HMTS-1200 was used to carry out triaxial hydromechanical coupling deformation tests on fractured basalt under water pressure along a cyclic loading and unloading path. The following test results were obtained. During cyclic water pressure loading and unloading, the additional axial deformation exhibits the characteristic fluctuations of compression-expansion-compression, whereas the lateral deformation exhibits the characteristic fluctuations of expansion-compression-expansion. Under hydraulic-mechanical coupling, the coupling of the axial pressure and the water pressure is noticeable. The lower the axial pressure is, the more noticeable the additional specimen deformation is. The deformation modulus of the fractured basalt under triaxial stress-hydraulic pressure coupling depends strongly on the loading-unloading of the water pressure and the confining pressure. The deformation modulus is logarithmic in the number of cycles and linear in the water pressure. The abovementioned test results serve as an important reference for the study of hydraulic coupling characteristics of and time effects on bank rock mass deformation parameters during reservoir operation.

Effects of material properties on structural behaviour and safety evaluation of an old arch dam

Safety evaluation is an important task to verify performance of a dam during its service. For an old dam, the material properties vary from the designed value significantly affecting structural performance. This study investigates the effects of material properties of dam concrete and foundation rock on the structural behaviour of an old concrete arch dam during operation. The dam safety is evaluated by using a three-dimensional finite element model (FEM). All main loads, such as water pressure, dam self-weight, and thermal load, are considered in the analysis. An existing 54-year-old concrete arch dam, located in a tropical climate region in Thailand, is employed as a case study. The analysis results show that deformation modulus of the foundation, modulus elasticity of concrete, and the variation of reservoir water level during operation are key factors affecting the dam response. With a deformability modulus of foundation and elasticity modulus of dam concrete, which are about 20 GPa and 44.2 GPa, respectively, a good agreement in dam deflections between the analysis and the current monitored data from plumb line equipment can be obtained. It should be noted that the material properties are different from designed value significantly. Finally, safety evaluation can be properly conducted based on current material properties.

A novel test setup for determining waterproof performance of rubber gaskets used in tunnel segmental joints: Development and application

In this paper, a novel test setup was proposed to perform mechanical and waterproof tests for rubber gaskets used in tunnel segmental joints. Based on the newly developed setup, it is available to simulate typical joint deformation observed during construction and operation stages, e.g., opening, offset, rotation, and eccentric compression. The components and configurations of the setup were presented in detail. Special treatments were subsequently illustrated for ensuring water pressure loading and rational leakage mode. The setup was applied using test specimens obtained from a rapid rail transit shield tunnel under design. Four groups of gasket mechanical tests and 22 groups of gasket waterproof tests were carried out to evaluate the reliability and functionality of the setup. The load-deformation relationship was adopted to demonstrate gasket-in-groove mechanical behavior, while the factors influencing gasket waterproofness were also considered through analyzing the sealant capacity measured under different conditions. The results show that there exists a close correlation between the mechanical and waterproof performance of gaskets. Deterioration of gasket waterproofness generally occurs due to joint offset. Positive and negative joint rotation leads to the opposite variation trend of sealing performance for gaskets. The water leakage phenomenon observed in tests shows good agreement with the field survey results. The developed test setup and methodology provide novel insights into the waterproof examination of gaskets in complex situations.

The simulation of high compressive stress and extrusion phenomenon for concrete face slabs in CFRDs under strong seismic loads

The evaluation of high compression zones for anti-seepage face slabs is an increasingly important task in the safety evaluation of high concrete faced rock-fill dams (CFRDs). This manuscript uses the scaled boundary finite element method (SBFEM) to construct a cross-scale model of the rockfill and bedrock in a high CFRD. Nonconforming elements are applied to independently refine the mesh locally in the concrete face slab, which allows an accurate modeling of the rotating and bending phenomenon experienced by the face slab zone. Meanwhile, the non-matching node interface is introduced to connect the locally refined face slab mesh to the rockfill zone and obtain the final cross-scale model for refined analysis. The generalized plastic constitutive model and a state-dependent elasto-plastic interface constitutive model are employed to capture the complex behaviors of rockfill and soil-structure interaction (SSI). Leveraging the above approaches, static and dynamic analyses of a high CFRD are conducted to identify high compressive stress zones and simulate the extrusion damage. The results indicate that self-weight, water pressure, friction force and seismic loads contribute to rotating and bending between face slabs, and can lead to significant local stress concentration within the surface of face slab near the longitudinal joints and may potentially extrusion damage.

Experimental Study on the Failure Mechanism of Tunnel Surrounding Rock under Different Groundwater Seepage Paths

The influence of groundwater on tunnel engineering is very complicated. Due to the complexity of water flow water pressure transfer and uncertain defects in the stratum, all of which are key factors with regard to the design of tunnel engineering. Therefore, the variation of surrounding rock during excavation and the deformation and failure of soft surrounding rock under different seepage paths of underground water after excavation systematically. Experimental results showed that the stress change of surrounding rock caused by tunnel excavation can be divided into 3 stages: stress redistribution, stress adjustment, and stress rebalancing. In the process of water pressure loading, water flow rate is closely related to the experimental phenomenon. The between stable loading water pressure pore water pressure of the tunnel surrounding rock and the distance from the measuring point to the edge of the tunnel obey the exponential function of the decreasing growth gradient. With the increase of loading pressure, the pore water pressure and stress at the top of the tunnel increase, and the coupling of stress field and seepage field on both sides of surrounding rock more and more intense. The failure process of the tunnel can be divided into 6 stages according to the damage degree. The final failure pattern of the surrounding rock of the tunnel is mainly determined by the disturbed area of excavation. The arched failure area and the collapse-through failure area are composed of three regions. The surrounding rock is characterized by a dynamic pressure arch in the process of seepage failure, but it is more prone to collapse failure at low water pressure. The results of this study are the progressive failure mechanism of tunnel under different groundwater seepage paths and would be of great significance to the prevention of long-range disasters.

Cracking Characteristics of the Surrounding Rocks of a Hydraulic Tunnel Under High Geothermal Conditions: A Model Test

In the present study, a physical model test was used to investigate the cracking characteristics of the surrounding rocks of hydraulic tunnels under high geothermal conditions. Based on similarity theory, a similar material was developed to simulate the intact and hard rocks in thermo-hydro-mechanical (THM) coupling fields; this material was used to cast a large-scale model tunnel. A new loading system, including a temperature loading system and a water pressure loading system, was designed to improve upon conventional laboratory hydraulic tunnel testing and provide a means of better understanding the fracture behavior of solid media. An acoustic emission (AE) monitoring system, thermocouples and osmometers were used to reveal the real-time evolution of the temperature field, seepage pressure field and crack propagation. The test results showed that compared to a hydraulic tunnel without high geotemperature, the critical internal water pressure of the hydraulic tunnel under high geothermal conditions decreased significantly. After the initiation of main cracks was induced by hydraulic fracturing, due to THM coupling, a certain number of secondary cracks initiated and developed between the main cracks. In this process, the trend of the secondary crack tip deviated from the radial direction, resulting in a more developed and complicated evolution of cracks (including main cracks and secondary cracks). This was different from the cracking behavior of surrounding rocks without a high geothermal gradient, in which only a few main cracks due to hydraulic fracturing were observed. An obvious multifield THM coupling effect was observed under high-geotemperature conditions, and cracks propagated and damage increased in the surrounding rocks in a discontinuous and step-like manner. The number and source locations of the cracks recorded by the AE monitoring system were in good agreement with the evolution of the temperature field and seepage pressure field. In addition, FLAC3D numerical simulations based on the thermo-hydro-mechanics and damage (THMD) model revealed that high geotemperatures and in situ stresses significantly influenced on the cracking mode of the surrounding rocks of hydraulic tunnels under high geotemperatures. The results obtained in this study provide a better understanding of the cracking characteristics of the surrounding rocks of hydraulic tunnels under high geothermal conditions and are useful for the design of hydraulic tunnels.

Development and application of large-scale model test system for underwater shield tunnels

In order to simulate the characteristics of underwater shield tunnels, a new large-scale model test system with high water pressure and high stress loading capacity was developed. The loading control mode of the hydraulic system can perform uniform loading and gradient loading. Moreover, the vertical and horizontal hydraulic loading can reach 0·8 MPa and 1·6 MPa. The water pressure loading system has a maximum capacity of 0·5 MPa. Based on an actual project, a model test of an underwater shield tunnel lining under real soil and water pressure conditions was carried out. New segment joints of the model were developed during the model testing. The lateral pressure coefficient at rest of the model strata was slightly larger than 0·5, and close to that of the field strata. It was also found that the water pressure had a reducing effect on the soil pressure under large buried depth and high water pressure conditions. This system can mostly meet the requirements of underwater or underground engineering model tests.

Onsite Tests and Numerical Simulation of Broken Rock Zones in Surrounding Rocks of Seepage Roadways under Blasting

To study the influence of blasting vibration on the broken rock zone around a seepage roadway and provide guidance for design of the roadway support, the broken rock zones around rock of seepage roadways under production blasting vibration are determined by onsite tests in a mining area, Daye iron mine. During the testing process, it is found that blasting vibration causes internal cracks of surrounding rocks to initiate and develop, the fracture density increases, the acoustic wave velocity of rock mass decreases, and the broken rock zones expand. At the same time, through onsite observation, it is found that blasting vibration results in crack development and formation of a water pathway to lead to surface water into the ground. The mechanical response around rock of the seepage roadway under blasting vibration is simulated by the two-dimensional realistic fracture progress analysis calculation software (RFPA2D). It is found that internal cracks of roadway surrounding rock initiate, propagate, and join up gradually, and the fracture range is expanding under the seepage water pressure, ground stress, and cyclic loads, and the broken rock zones also expand. The results from numerical simulation are consistent with the results of onsite tests. It is also found that the tensile stress appears around some cracks, leading to part of the cracks more likely to generate shear failure under the seepage water pressure during simulation.