State Key Laboratory of Geomechanics and Geotechnical Engineering

Wuhan, China

State Key Laboratory of Geomechanics and Geotechnical Engineering

Wuhan, China
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Pan H.,Chinese Academy of Sciences | Pan H.,CAS Chengdu Institute of Mountain Hazards and Environment | Huang J.,Yunnan University | Wang R.,State Key Laboratory of Geomechanics and Geotechnical Engineering | And 3 more authors.
Journal of Earth Science | Year: 2013

Debris flows are the one type of natural disaster that is most closely associated with human activities. Debris flows are characterized as being widely distributed and frequently activated. Rainfall is an important component of debris flows and is the most active factor when debris flows occur. Rainfall also determines the temporal and spatial distribution characteristics of the hazards. A reasonable rainfall threshold target is essential to ensuring the accuracy of debris flow pre-warning. Such a threshold is important for the study of the mechanisms of debris flow formation, predicting the characteristics of future activities and the design of prevention and engineering control measures. Most mountainous areas have little data regarding rainfall and hazards, especially in debris flow forming regions. Therefore, both the traditional demonstration method and frequency calculated method cannot satisfy the debris flow pre-warning requirements. This study presents the characteristics of pre-warning regions, included the rainfall, hydrologic and topographic conditions. An analogous area with abundant data and the same conditions as the pre-warning region was selected, and the rainfall threshold was calculated by proxy. This method resolved the problem of debris flow pre-warning in areas lacking data and provided a new approach for debris flow pre-warning in mountainous areas. © 2013 China University of Geosciences and Springer-Verlag Berlin Heidelberg.


Ge X.R.,Shanghai JiaoTong University | Ge X.R.,CAS Wuhan Institute of Rock and Soil Mechanics | Ge X.R.,State Key Laboratory of Geomechanics and Geotechnical Engineering | Hou M.X.,Shanghai JiaoTong University
Science China Technological Sciences | Year: 2012

As a main constituent of geological body, the rock masses have distinct differences from other materials, one of which is that rock masses are initially stressed in their natural states. Hence, it is an extremely challenging and significant research project to know the present residual stress of the rock masses in the earth's crust. Although some regularities of distribution of in-situ rock stresses can be deduced, the basic means to study the state of rock stress is in-situ stress measurement. After a brief review of several measuring methods of in-situ 3D rock stress, a new one, borehole wall stress relief method (BWSRM) to determine the in-situ 3D rock stress tensor in a single drilled borehole was proposed. Based on the principle of in-situ rock stress measurement with BWSRM, an original geostress measuring instrument was designed and manufactured. Preliminary experiments for determination of in-situ stress orientation and magnitude were carried out at an experimental tunnel in Jinping II hydropower station in China, where the buried depth of overburden was about 2430 m. The results showed that it was feasible to measure the in-situ 3D rock stresses with BWSRM presented in this paper. The BWSRM has a broad prospect for in-situ 3D rock stress measurements in practical rock engineering. © Science China Press and Springer-Verlag Berlin Heidelberg 2012.


Ge X.R.,CAS Wuhan Institute of Rock and Soil Mechanics | Ge X.R.,State Key Laboratory of Geomechanics and Geotechnical Engineering | Ge X.R.,Shanghai JiaoTong University
Harmonising Rock Engineering and the Environment - Proceedings of the 12th ISRM International Congress on Rock Mechanics | Year: 2012

A new approach, named the Vector Sum Method (VSM), is proposed to analyze the anti-sliding stability problems for slope, dam foundation, etc. It is well known that the strength reduction method is generally applied in this field. But the stress state due to the strength reduction is a virtual state rather than a real one. So the safety factor calculated based on a virtual stress state is not physical sound. Some disadvantages of slope and dam foundation stability analysis methods based on strength reduction principle are discussed. To overcome the limitation of the strength reduction method, the VSM uses the real strength parameters rather than the reduced parameters to compute the stress field. The safety factor is computed based on the real stress state and the vector sum algorithm. Several typical examinations calculated by the vector sum method are presented. The comparison between results shows that the VSM is reasonable. The safety factor is calculated by an explicit formula in 2D case while by iterative computation in 3D case after the stress fields are acquired by finite element method or other methods. The VSM can be well applied to 3D problems for its simplicity and efficiency. © 2012 Taylor & Francis Group, London.


Wei L.-D.,CAS Wuhan Institute of Rock and Soil Mechanics | Wei L.-D.,State Key Laboratory of Geomechanics and Geotechnical Engineering | Wei C.-F.,CAS Wuhan Institute of Rock and Soil Mechanics | Wei C.-F.,State Key Laboratory of Geomechanics and Geotechnical Engineering
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2014

When the traditional joint element methods are used to simulate the failure process of rock, it is necessary to increase the elements and the nodes, and the data processing is extremely complex. In order to more efficiently simulate the interaction between nodes in the finite element in fractured rock, a new simulating method is proposed. A simple interface element including two nodes, called the generalized joint element here, is suggested. Its fundamental equations are deduced, and its element organization method is offered. Using the generalized joint elements to simulate the joint in rock, it is necessary to increase the elements compared to the finite element mesh, and not necessary to change or increase the nodes. Numerical experiments of simulation of a rock joint indicate that the generalized joint element method is effective, and the accuracy of stress with the generalized joint elements is equal to that with the traditional ones.


Zhan Y.-X.,CAS Wuhan Institute of Rock and Soil Mechanics | Zhan Y.-X.,State Key Laboratory of Geomechanics and Geotechnical Engineering | Yao H.-L.,CAS Wuhan Institute of Rock and Soil Mechanics | Yao H.-L.,State Key Laboratory of Geomechanics and Geotechnical Engineering | Jiang G.-L.,Southwest Jiaotong University
Journal of Central South University | Year: 2013

Pile-slab structure roadbed is a new form of ballastless track for high speed railway. Due to lack of corresponding design code, based on the analysis of its structure characteristics and application requirements, it is proposed to carry out load effect combination according to ultimate limit state and serviceability limit state, and the most unfavorable combination of each state is chosen to carry through design calculation for pile-slab structure. Space model of pile-slab structure can be simplified as a plane frame model, by using the orthogonal test method, and the design parameter of pile-slab structure is optimized. Moreover, based on the engineering background of Suining-Chongqing high-speed railway, the dynamic deformation characteristics of pile-slab structure roadbed are further researched by carrying on the indoor dynamic model test. The test results show that the settlement after construction of subgrade satisfies the requirement of settlement control to build ballastless track on soil subgrade for high-speed railway. Slab structure plays the role of arch shell as load is transmitted from slab to pile, and the vertical dynamic stress of subgrade soil is approximately of "K" form distribution with the depth. The distribution of pile stress is closely related to soil characteristics, which has an upset triangle shape where the large dynamic stress is at the top. Pile compared with soil shares most dynamic stress. Pile structure expands the depth of the dynamic response of subgrade and improves the stress of subgrade soil, and the speed of train has limited effect on dynamic response. These results can provide scientific basis for pile-slab structure roadbed used on soil subgrade. © 2013 Central South University Press and Springer-Verlag Berlin Heidelberg.


Zhang X.-W.,CAS Wuhan Institute of Rock and Soil Mechanics | Zhang X.-W.,State Key Laboratory of Geomechanics and Geotechnical Engineering | Kong L.-W.,CAS Wuhan Institute of Rock and Soil Mechanics | Kong L.-W.,State Key Laboratory of Geomechanics and Geotechnical Engineering
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2013

The slow variability of the physical-mechanical properties of clay in atmospheric environment with normal temperature, pressure and concentration is studied. By taking the Zhanjiang clay as the research object, the soil color of atmospheric environment changes from blue-gray, green-gray into yellowish brown, brown under impact, and the degree of particle agglomeration is enhanced. Further, the plasticity and expansibility, shrinkage, sensitivity, structural yield pressure are all reduced. Owing to the atmospheric oxidation, the mechanical properties of the clay is strengthened, but its long-term mechanical stability is depressed and the damage is potential since the structural strength is weakened. A generalized structural model for the variability of clay by atmospheric oxidation is established and discussed. The results show that the variation of atmospheric environment leads to change of redox environment, the chemical reaction among water-soil and atmosphere is carried out and moved, and the connection ways of micro-fabric unit are changed. Furthermore, the microstructure is transformed and the stability of mechanical system is affected. Oxidation reaction prompts the valence of the iron ions in the soil to increase, and they migrate along with the aging reaction of colloidal iron oxide to the crystalline state under the concentration gradient and the adsorption energy of soil particle surface. Iron oxide exists in the form of the mixed iron replaced by the coated iron one, and the microstructure becomes flocculation structure with low plasticity, physical contact and weak structural strength. This study may provide a theoretical support for the prevention and control of geological and engineering disasters owing to environmental change.


Sun J.-Z.,Wuhan University of Technology | Sun J.-Z.,State Key Laboratory of Geomechanics and Geotechnical Engineering | Xiao W.-H.,Wuhan University of Technology
Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of Technology | Year: 2011

In view of the inconvenience to obtain internal deformation of soil and other shortcomings in the existing shield model test, transparent soil is synthesized by means of calcium bromide solution and fused silica, the testing system of shield model is designed on this basis. Cutter head of shield machine model can be rotated, and also be retracted into the shield shell, and both are controlled with screw, this may be used to model shield tunneling and decreasing of support force at tunnel face. During shield tunneling the laser is used to illuminate the cross-section of transparent soil in front of the shield, the digital camera is used to capture the images continuously, internal soil deformations are calculated using particle image velocimetry. So the microscopic mechanism of tunneling induced soil deformation is visualized truly.


Lu H.,Wuhan University | Liu Q.,Wuhan University | Liu Q.,State Key Laboratory of Geomechanics and Geotechnical Engineering | Chen C.,State Key Laboratory of Geomechanics and Geotechnical Engineering | Wu Y.,Wuhan University
Disaster Advances | Year: 2012

The hard and soft interbedding stratum is widely distributed in the Three Gorges reservoir area and the Sichuan basin. Many landslide hazards occurred in this kind of stratum and its disaster mechanism is very complex. In this paper, take the typical hard and soft interbedding slope as an example, we made laboratory test on the rock mass and established a geological model of the hard and soft interbedding slope. Furthermore, based on the slope stability analysis and considering creep properties of weak intercalated layer, the disaster mechanism is clarified and appropriate prevention measures are proposed. The research here can provide technical guidance for slope stability analysis in the Three Gorges reservoir area and the engineering safety in the construction of the western development.


Chen C.,State Key Laboratory of Geomechanics and Geotechnical Engineering | Zhou Z.-M.,State Key Laboratory of Geomechanics and Geotechnical Engineering
Journal of Central South University | Year: 2013

Numerous experimental studies reveal that the mechanical and deformational behaviors of sands are dependent on the combined effect of void ratio and stress. To predict this complex behavior of sands, a hypo-elastic model is developed based on the cross-anisotropic elasticity model, which involves four parameters: bulk module, tangent Young's module, volume deformation coefficient and Poisson ratio. A parameter defined as virtual peak deviatoric stress dependent on state parameter is introduced into hyperbolic stress-strain relationship to determine tangent Young's module. In addition, an existing fitting equation for isotropic compression curves and an existing dilatancy equation, which can consider the effect of state of sands, are employed to determine bulk module and volume deformation coefficient. Thirteen model constants are involved in the proposed model, the values of which are fixed for a sand over a wide range of initial void ratios and initial confining pressures. Well known experimental data for drained and undrained triaxial compression tests of Toyoura sand are successfully modeled. © 2013 Central South University Press and Springer-Verlag Berlin Heidelberg.


Yu F.,State Key Laboratory of Geomechanics and Geotechnical Engineering | Chen S.,State Key Laboratory of Geomechanics and Geotechnical Engineering | Zhang Y.,State Key Laboratory of Geomechanics and Geotechnical Engineering
Innovative Materials and Design for Sustainable Transportation Infrastructure - Selected Papers from the International Symposium on Systematic Approaches to Environmental Sustainability in Transportation | Year: 2015

The key to the project of lunar regolith sampling lies in the interactive mechanism between drilling implements and lunar regolith under special circumstances of lunar surface. Targeted at mechanical properties of CAS-1 lunar regolith simulant under low stress levels, the tri-axial test, direct shear test and compression test were carries out. Research findings show that: (1) Under low stress levels, when void ratio e ranges between 0.8 and 1.1, the value of cohesion c is 2.8∼ 5.0kPa and internal friction angle φ 39.84° ∼41.09°, and the compression curves show varying features of first upward concave and then downward concave; when e ranges between 0.9 and 1.1, initial compression modulus E0 is 12.647∼3.923 MPa, and the stress-strain curves consist of hardening and softening stages. During the softening stage, the decreasing rate is faster, and the stress ratio is concentratively distributed along the curves. (2) Under low stress levels, the smaller the value of e, the larger the peak deviator stress/stress ratio and the smaller the peak axial strain, but they all range between 2% and 5%. (3) The initial tangent slope α, peak stress ratio ηf and residual stress ratio ηjr are all log-linear to the confining pressure P0, but under low stress levels, α falls slowly, and the initial tangent modulus Gi(1/a) changes within a smaller range, whereas η/fand η/rtfall faster.

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