Model Experiment And Calculation Analysis Of Excavation-Seepage Stability For Shallow Shield Tunneling In Sandy Ground, 2020 School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China
Model Experiment And Calculation Analysis Of Excavation-Seepage Stability For Shallow Shield Tunneling In Sandy Ground, Bo Mi, Yan-Yong Xiang
Rock and Soil Mechanics
Regarding the influence of seepage on face support pressure and ground collapse mode in shallow shield tunnel excavation, an experimental system composed of a shallow shield tunnel excavation-seepage model and a setup of measurement and data acquisition is designed and established, with consideration of pore water pressure in the excavation chamber and face plate opening ratio. The saturated soil pressures and pore water pressures at the face and settlements of surrounding strata are measured under various steady-state seepage conditions, as the soil input into the excavation chamber is gradually increased. Correspondingly, numerical simulations and limit equilibrium calculations are carried out. …
Research On Optimization Of Frozen Wall Thickness Of Underwater Tunnel Based On Fluid-Solid Coupling Theory, 2020 Key Laboratory of Ministry of Education for Efficient Mining and Safety of Metal Mine, University of Science and Technology Beijing, Beijing 100083, China
Research On Optimization Of Frozen Wall Thickness Of Underwater Tunnel Based On Fluid-Solid Coupling Theory, Li-Fu Zheng, Yong-Tao Gao, Yu Zhou, Shu-Guang Tian
Rock and Soil Mechanics
The design of underwater tunnel has special requirements for the thickness of the frozen wall. To improve the frozen wall design of the cross-passage in the Maliuzhou waterway section of the Zhuji Intercity Rail Transit Project, based on the fluid-solid coupling theory, the finite difference method is adopted to analyse the stability of the underwater tunnel numerically. By simulating underwater tunnel with different frozen wall thickness, the responses of underwater tunnel stability to the thickness of frozen wall are discussed and the optimizaitons of frozen wall thickness are done. Some findings are as follows. Compared with the non-permeability model, the …
Analysis Of The Evolution Of Excess Pore Water Pressure In Soft Soil Under Linear Unloading, 2020 Rock and Soil Mechanics
Analysis Of The Evolution Of Excess Pore Water Pressure In Soft Soil Under Linear Unloading, Xu-Chao Shi, Yun-De Sun
Rock and Soil Mechanics
At present, the research on the consolidation deformation of soft soil under unloading mainly focuses on the instantaneous unloading. In order to clarify the evolution of consolidation deformation of soft soil under linear unloading, through the one-dimensional consolidation theory of Terzaghi and the principle of effective stress, an effective method is proposed to study the general solution of the soft soil foundation under the arbitrary unloading rate and solve the analytical solution of the consolidation equation under linear unloading. The results show that: (1) the negative excess pore pressure generated in soft soil foundation under linear unloading can be divided …
A Case Study Of Excavation Damage Zone Expansion Time Effect In Hard Brittle Country Rock Under High Geostress:Characteristics And Mechanism, 2020 School of Civil Engineering and Construction, Hubei University of Technology, Wuhan, Hubei 430068, China
A Case Study Of Excavation Damage Zone Expansion Time Effect In Hard Brittle Country Rock Under High Geostress:Characteristics And Mechanism, Yan-Shuang Yang, Hui Zhou, Song-Hua Mei, Zhan-Rong Zhang, Jin-Lan Li
Rock and Soil Mechanics
The excavation damage zone (EDZ) in hard brittle country rock exhibits noticeable time effect after excavation, as rock strength varies with time caused by the high geostress, which leads to the development of surrounding rock excavation damage zone and shows time-dependent characteristics. The LSSVM-PSO intelligent inversion analysis method considering time effect was established based on the time effect evolution model of rock strength, and measured EDZ data collected in the test tunnel of Jinping Ⅱ Hydropower Station, such as borehole monitoring, ultrasonic test and deformation monitoring were used as target functions. The orthogonal design method, least square support vector machine …
Shaking Table Model Test On Seismic Responses Of Utility Tunnel With Joint, 2020 Key Laboratory of New Technology for Construction of Cities in Mountain Area of Ministry of Education, Chongqing University, Chongqing 400045, China
Shaking Table Model Test On Seismic Responses Of Utility Tunnel With Joint, Li Feng, Xuan-Ming Ding, Cheng-Long Wang, Zhi-Xiong Chen
Rock and Soil Mechanics
Deformation joints are universal in underground utility tunnels that belong to the shallow-buried and slender structure. Under seismic loads, the vibration response of the underground structure with a joint will be affected to a great extent. However, the studies on this problem are limited. In this paper, based on the shaking table model test that considers the influence of joints, the seismic response characteristics of the underground utility tunnel under seismic excitation with different waveforms and different peak accelerations were studied. The acceleration, soil pressure, displacement, strain, and bending moment were measured and analysed. The results indicated that the vibration …
Impacts Of Pit Excavation On Foundation Piles In Deep Silty Soil By Centrifugal Model Tests, 2020 Research Center for Geotechnical Engineering Technology of Hebei Province, Shijiazhuang, Hebei 050227, China
Impacts Of Pit Excavation On Foundation Piles In Deep Silty Soil By Centrifugal Model Tests, Guo-Hui Wang, Wen-Hua Chen, Qing-Ke Nie, Jun-Hong Chen, Hui-Hong Fan, Chuan Zhang
Rock and Soil Mechanics
The foundation pit excavation of a power plant located along the Yangtze River in Jiangsu province is selected to study the interaction mechanism between piles and soils during excavation of foundation pits in deep silty soft soil. Thus an indoor centrifugal model test with the similarity ratio of 1:50 is designed. The influence of foundation pit excavation on existing pile and surrounding soil in deep silty soft soil are analyzed from different aspects including the pile strain, pile displacement, pile top displacement, surface settlement and soil deformation influence range, pile bending moment and pore water pressure. Results from the centrifugal …
Study On Anisotropic Permeability Model For Mixed Kaolin-Montmori- Llonite Clays, 2020 Engineering Research Center of Urban Underground Development of Zhejiang Province, Hangzhou, 310058, China
Study On Anisotropic Permeability Model For Mixed Kaolin-Montmori- Llonite Clays, Jie Xu, Jian Zhou, Ling-Hui Luo, Liang-Gui Yu
Rock and Soil Mechanics
A perfect anisotropic permeability model is helpful to guide the drainage and grouting scheme of underground buildings during construction and operation period. To study permeability anisotropy model, mixed kaolinite-montmorillonite clays were used in a series of permeation experiments by triaxial permeameter, and the development of anisotropic permeability model was attempted from both macroscopic and microscopic perspectives. The results show that: as the amount of bentonite increases, the small pores increase, but the large pores decrease; as the consolidation stress increases, all pores decrease, and the maximum pore size decreases. Macroscopically there is no correlation between the void ratio considering the …
Experimental And Model Research On Shear Creep Of Granite Under Freeze-Thaw Cycles, 2020 Rock and Soil Mechanics
Experimental And Model Research On Shear Creep Of Granite Under Freeze-Thaw Cycles, Feng-Rui Zhang, An-Nan Jiang, Xiu-Rong Yang, Fa -Yi Shen
Rock and Soil Mechanics
To study the effect of freeze-thaw on the shear creep characteristics of engineering rocks in cold regions, the granite samples from Huibai tunnel in Jilin province were taken as the research object, and the microscopic characteristics and shear creep tests of samples under different freeze-thaw cycles were carried out. The results show that: 1) With the increase of freeze-thaw cycles, the cracks and voids in the samples develop continuously, and the damage of rock surface becomes more and more obvious. 2) The pores in the sample are mainly composed of small and medium pores, and the porosity increases nonlinearly with …
Experimental Investigation Of Accelerated Failure Of Creep Rock Induced By Impact Disturbance, 2020 Institute of Underground Space for Stability and Support of Surrounding Rock, Heze University, Heze, Shandong 274015, China
Experimental Investigation Of Accelerated Failure Of Creep Rock Induced By Impact Disturbance, Qing-Yuan Wang, Jie Liu, Pei-Tao Wang, Fei Liu
Rock and Soil Mechanics
Rockmass may be in a creep state for a long time during underground mining. The failure progress of surrounding rock mass may be accelerated due to the mining disturbance. The rockmass failure is usually later than the mining activities and shows an obvious time lag effect, which brings difficulty in predicting the occurrence of engineering disaster. Given this problem, impact-creep tests of rock specimens were conducted under multi-cycle drop weight using a rock rheology-impact test machine. The changing law of axial strain of sandstone specimens was analyzed. The influence of creep state, impact times of drop weight, and impact energy …
Experimental Investigation On The Dynamic Response Of Pile Group Foundation On Liquefiable Ground Subjected To Horizontal And Vertical Earthquake Excitations, 2020 Rock and Soil Mechanics
Experimental Investigation On The Dynamic Response Of Pile Group Foundation On Liquefiable Ground Subjected To Horizontal And Vertical Earthquake Excitations, Heng-Yuan Zhang, De-Ling Qian, Chao Shen, Qi-Quan Dai
Rock and Soil Mechanics
To investigate the dynamic response of pile group foundation on liquefiable ground subjected to horizontal and vertical (bidirectional) coupling earthquake excitations, a shaking table model test for a dynamic interaction system with liquefiable ground –pile group foundation–frame tube structure was conducted. Different types of earthquake motions were selected as the excitations for the shaking table test, and then the influence of bidirectional coupling earthquake excitations on the dynamic response of liquefiable ground and pile group foundation were analyzed by comparing the test results of soil acceleration, excess pore water pressure and pile group strain subjected to horizontal unidirectional and bidirectional …
Development And Application Of Contact Algorithms For Rock Shear Fracture Surface, 2020 Rock and Soil Mechanics
Development And Application Of Contact Algorithms For Rock Shear Fracture Surface, Qiu-Feng Ma, Yue-Ping Qin, Tian-Bai Zhou, Xiao-Bin Yang
Rock and Soil Mechanics
To overcome the inefficiency of existing numerical algorithms in calculating the contact slip law of complex fracture surfaces, a new numerical calculation algorithm was proposed by adoption of the idea of boundary element method. In this algorithm, all nodes were located at the boundary of rock blocks, and the interaction force between rock blocks and the displacement of rock blocks were calculated by using the explicit differential method. The algorithm was validated by two simulation experiments, i.e. “ball sliding on paraboloid” and “dumbbell on the inclined plane”. The results show the algorithm can accurately describe the contact between objects and …
Study On The Influence Of Bedding Plane On The Fracturing Behavior Of Sandstone, 2020 State Key Laboratory for Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China
Study On The Influence Of Bedding Plane On The Fracturing Behavior Of Sandstone, Bin Li, Da Huang, Wen-Zhu Ma
Rock and Soil Mechanics
The mechanical behavior of layered stone is much influenced by the weak bedding planes. To further explore how the layered structure influences the fracture characteristic of layered sandstone, a series of three-point-bending tests on sandstone specimens with different inclination angles was conducted and the anisotropy of fracture toughness and fracture pattern were discussed. Then a numerical model based on cohesive elements was proposed to simulate the fracture of semi-circular sandstone specimens under three-point-bending test and the effects of bedding strength on the fracturing behavior of semi-circular bending(SCB) specimens with different inclination angles were discussed by simulation with the proposed model. …
Analysis Of Energy Evolution During The Step Loading And Unloading Creep Experiments Of Sandstone, 2020 School of Mechanics and Civil Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China
Analysis Of Energy Evolution During The Step Loading And Unloading Creep Experiments Of Sandstone, Chao Han, De-Peng Pang, De-Jian Li
Rock and Soil Mechanics
The uniaxial step loading and unloading creep experiments were conducted on the sandstone samples from Shaanxi Province to analyze the law of energy evolution of the samples during the process of deformation and failure. The results show that with the increase of cyclic series, the dissipation energy of each grade exhibits a nonlinear increase and the plastic strain energy of each grade is relatively stable. The dissipation energy exceeding plastic strain energy can be regarded as a precursor energy characteristic of the sample failure. By defining the correlation coefficient and establishing the relationship between energy and deformation, it can be …
Evolution Law Of Pore-Size Distribution In Soil-Water Retention Test, 2020 State Key Laboratory of Structural Analysis of Industrial Equipment, Department of Engineering Mechanics, Dalian University of Technology, Dalian, Liaoning 116085, China
Evolution Law Of Pore-Size Distribution In Soil-Water Retention Test, Geng Niu, Long-Tan Shao, De-An Sun, Chang-Fu Wei, Xiao-Xia Guo, Hua Xu
Rock and Soil Mechanics
This paper is to measure the soil-water retention curves (SWRC) of undisturbed and compacted soil specimens and compare the differences in measured data between these two soils. The mercury intrusion porosimetry (MIP) tests are conducted to explore the difference in the pore size distributions (PSD) between the undisturbed and compacted specimens and investigate the evolution law of PSD during drying. By considering shrinkage during drying, the basic parameters of SWRC can be determined based on the PSD. The results show that the undisturbed specimens in the wide suction range exhibit a unimodal PSD. The saturated compacted-specimen exhibits a unimodal PSD, …
Methods Of Determining The Minimum Number Of Samples For Statistical Measurement Of Rock Joint Roughness, 2020 Rock and Soil Mechanics
Methods Of Determining The Minimum Number Of Samples For Statistical Measurement Of Rock Joint Roughness, Qin-Kuan Hou, Rui Yong, Shi-Gui Du, Min-Na Xu, Ze-Min Cao
Rock and Soil Mechanics
The rock joint roughness has many characteristics like heterogeneity, anisotropy, nonuniformity and scale effect. In engineering practice, different statistical methods are utilized for analyzing the rock joint roughness due to its uncertainty. However, previous studies often neglected the impact of insufficient samples on statistical results. To solve the problem that reasonable number of samples cannot be determined during the statistical measurement of joint roughness, the methods based on the coefficient of class ratio analysis and the simple random sampling principle are proposed for determining the minimum number of samples (MNS), respectively. In the case study, the MNS of statistical measurements …
Study Of Ground Motion Effect Of Trapezoidal Valley Site Based On Centrifuge Shaking Table Test, 2020 Key Laboratory of Earthquake Engineering and Engineering Vibration, Institute of Engineering Mechanics, China Earthquake Administration, Harbin, Heilongjiang 150080, China
Study Of Ground Motion Effect Of Trapezoidal Valley Site Based On Centrifuge Shaking Table Test, Ping Li, Yu-Dong Zhang, Tao Bo, Jun-Ru Gu, Sheng Zhu
Rock and Soil Mechanics
Studying the seismic effects of valley site has critical guiding significance for site selection and aseismic design. Based on the analysis of centrifuge shaking table tests, the ground motion response pattern of the trapezoidal valley was studied. The results showed that there was a certain amplification effect of ground motion in the bedrock valley site. The amplification effect varied with the change of terrain, but the amplification effect was not significant. Different site locations had a small influence on the response spectrum. In the bedrock-overburden model, an obvious increase of the ground motion magnification was observed at the bedrock surface. …
Tunnel Face Stability Analysis By The Upper-Bound Finite Element Method With Rigid Translatory Moving Element In Heterogeneous Clay, 2020 Key Laboratory of Engineering Structure of Heavy Railway of Ministry of Education, Central South University, Changsha, Hunan 410075, China
Tunnel Face Stability Analysis By The Upper-Bound Finite Element Method With Rigid Translatory Moving Element In Heterogeneous Clay, Feng Yang, Shi-Hua He, Yao-Jie Wu, Li-Yan Ji, Jing-Jing Luo, Jun-Sheng Yang
Rock and Soil Mechanics
The upper-bound finite element method with rigid translatory moving elements (UBFEM-RTME) is further improved to optimise its suitability for analysing the stability in heterogeneous clay. The method is applied to investigate the stability of the tunnel face in undrained clay layer subjected to surface surcharge. The variation of stability load ?s /cu0 and the morphological characteristics and discipline of the effective discontinuities mechanism are obtained for various combinations of dimensionless buried depth ratio C/D, dimensionless gravity parameter ?D/cu0 and the heterogeneous parameter ?D/cu0. The results reveal that C/D and ?D/cu0 have a significant effect on ?s /cu0 and failure mechanism. …
The Numerical Manifold Method For Boundary Integrals In Elastostatics, 2020 Rock and Soil Mechanics
The Numerical Manifold Method For Boundary Integrals In Elastostatics, Zhi-Bao Nie, Hong Zheng, Tao Wan, Shan Lin
Rock and Soil Mechanics
The traditional numerical manifold method (NMM) adopts the form of regional integration. This paper proposed a new NMM in the form of boundary integral by integrating the advantages of both the boundary element method (BEM) and the NMM, namely the dimension reduction of BEM and the flexibility of local base selection of NMM. For two-dimensional elastostatics problems, three different benchmark examples with analytical solutions are applied to verify the validity and efficiency of the newly proposed NMM. The results show that the accuracy of the proposed procedure can be effectively improved by increasing the order of the local basis.
Study And Application Of The Relationship Between Preferential Flow Penetration And Slope Deformation, 2020 Collaborative Innovation Center for Geo-hazard and Eco-environment in Three Gorges Area of Hubei Province, Yichang, Hubei 443002, China
Study And Application Of The Relationship Between Preferential Flow Penetration And Slope Deformation, Xiao-Hu Huang, Wu Yi, Hai-Feng Huang, Yong-Huang Deng
Rock and Soil Mechanics
The cracks on the ground surface will form a complete crack system gradually with the increase of the slope deformation. In view of the rainfall infiltration process of this type of landslide, it is pointed out that the preferential flow penetration developed along the dominant channel formed along the surface crack leads to the deterioration process of landslide stability and promotes the development of deformation. This paper systematically analyzes the relationship between the preferential flow penetration, the fluctuation of groundwater level and the slope deformation. The Wangjiapo landslide is investigate to reveal the temporal-spatial deformation evolution of the dominant channel …
Research On Direct Shear Behaviour And Fracture Patterns Of 3d-Printed Complex Jointed Rock Models, 2020 Beijing Key Laboratory of Urban Underground Space Engineering, University of Science and Technology Beijing, Beijing 100083, China
Research On Direct Shear Behaviour And Fracture Patterns Of 3d-Printed Complex Jointed Rock Models, Pei-Tao Wang, Zheng-Jun Huang, Fen-Hua Ren, Liang Zhang, Mei-Feng Cai
Rock and Soil Mechanics
Geometry and mechanical characteristics of joints are key factors affecting the shear behaviors and fracture patterns of jointed rock mass. Using 3D printing technique, experimental jointed rock specimens containing rough joints with varied joint roughness coefficient (JRC), different types of geometrical joints, and fractrues network were established respectively. Then direct shear tests were conducted on the jointed rock models to study the shear strength and failure patterns. The results show that the values of shear strength of jointed rock models fluctuate greatly with varied JRC curves. The peak shear displacement decreases with increasing amplitude of fluctuation. The lowest and highest …