Wei Zhong Chen

Estimation of Elastic Moduli of Non-persistent Fractured Rock Masses

Abbreviations E0 Young’s modulus of intact rock G0 Shear modulus of intact rock m0 Poisson’s ratio of intact rock Kn Fracture normal stiffness Ks Fracture shear stiffness E Effective elastic modulus of fractured rock mass E\i (Eki) Effective elastic modulus of fractured rock mass in the normal (shear) direction of the ith fracture sets G Effective shear modulus of fractured rock mass m Effective Poisson’s ratio of fractured rock mass a Half-length of fracture r The distance from fracture center along its length q Fracture density, defined as the number of fracture central points per square meter h Angle between loading direction and normal direction of fracture plane u Normal displacement jump of fracture faces u Average normal displacement jump of fracture faces V Shear displacement jump of fracture faces rn Resolved normal stress on fracture from far-field stress ss Resolved shear stress on fracture from far-field stress rk Tension stress of fractures rp Normal stress acting on fracture faces rp Averaged normal stress acting on fracture faces S Far-field shear stress DR The total excess elastic strain energy due to the existence of fractures DRfn The elastic strain energy stored in fracture due to normal stress DRrn The excess elastic strain energy stored in rock due to normal stress DRrs The elastic strain energy stored in rock due to shear stress DRfs The excess elastic strain energy stored in fracture due to shear stress A * D Parameters of excess strain energy terms for non-uniform deformation mode A D Parameters of excess strain energy terms for uniform deformation mode rn1rk1 The subscript 1 denotes the ultimate quantities in integrals

Study of Thermo-Rheology Characters of Rock under the Uni-Axial Compression

This paper introduces temperature effect to rock model. It sets up a thermo-visco-elastic-plastic rock model. Based on the rock model which consists of spring, dashpot and plastic elements under the condition of un-axial compression, the behaviors of the thermo-visco-elastic-plastic in rock are discussed, and the equations of the constitutive, creep, unload and relaxation have been obtained. This model can reflect the rock or rock mass average thermo-rheology character. Meanwhile, this study gives a explanation of the significances of this kind of model in the practical use.

Study on the Structure Model and Controlling Method of Subsidence in Flat Seam and Deep Mining

The stratum movement and surface subsidence is considered as a whole system in the research work. The key of the surface subsidence control lies first in having thorough knowledge of the dynamic changeable of the overlaying strata movement as the face advances so as to establish the corresponding structure mechanics subsidence model in flat seam and deep mining. The common characteristic of stratum movement and the development procedure of crack arch are described in this paper. The structure constituents of subsidence and their influencing factors are also analyzed. Meanwhile, the surface subsidence is determined by the compressing of coal wall and the bending of the overlying strata. Based on the ground observation by the global positioning system, the boundary angle and the motion angle are determined. Furthermore, according to the research law, one can predict and control the surface subsidence damages for the special geologic conditions.

Numerical Simulation of Humidity-Stress in Unsaturated Argillite Tunnel

An extension of Hoek-Brown criteria to include unsaturated behavior of argillite in porous medium is presented. The model is applied to simulate evolution of saturation degree in argillite and concrete in an experimental tunnel where field investigation of thermo-hydro-mechanical response of argillite and concrete will be done. Based on the laboratory experimental data, two different flow rules of water relative permeability and water saturation degree were suggested. The general evolution rules of saturation degree in argillite and concrete with time considering the effects ventilation are obtained.

Hydro-Mechanical Coupling Analyses of Cofferdam Stability of Taian Pumped Storage Power Station

Three-dimensional hydro-mechanical coupling analyses have been conducted on the water-tight structure of the cofferdam for both intake and outlet of Taian pumped storage power station, located in Shandong Province of China. In addition, the effects of excavation on the cofferdam and foundation slopes were also studied by using the 3D FLAC. The calculation results show that the central core of high-pressure grouting has a prefect anti-seepage effect and therefore is able to strengthen the stability of the cofferdam and foundation slopes. The excavation process has only some local effects on the cofferdam and does not greatly affect the global stability of the cofferdam. Therefore, no failure takes place around slope toes. The results show that the width of platform left on the excavation side is reasonable.

Study on Stability and Anchoring Effect of Jointed Rock Mass of An Underground Powerhouse

This present paper adopts a constitutive model for elastic damage of intermittently jointed rock mass, damage-evolution equations and a supporting model of damaged rock-bolt bar(DRBB) element to simulate effect of reinforcement. The results have indicated that the above method well describes the progressive failure process of the surrounding rock mass and the anchorage effect. The theoretical achievements are of referential value to designers.