Numerical Analysis on Dynamic Response of Saturated Elasto viscoplastic Soft Clay

In the framework of porous media model developed from mixtures theories, Solid skeleton of soft clay was viewed as elasto viscoplastic material,and an elasto viscoplastic model of saturated soft clay was established. According on the model of saturated so     

A Determination Method of Anchorage Length of Compression Anchor

The distribution of the axial stress and shear stress on the anchorage segment and the formulation for calculating the anchorage length were derived based on the stress analysis of the anchorage segment of compression anchor. And the effects of parameters, including the elastic modulus, poisson ratio, cohesion, and internal fiction angle of rock mass, on the anchorage length were studied. The results show that the anchorage length decreases with the increase of the elastic modulus, cohesion and internal friction angle of rock mass; and the anchorage length increases linearly but limited with increasing of poisson ratio of rock mass; and it also increases with increasing load.     

Simplified Elasto Plastic Analytical Model for Stiffened Steel Plate Shear Wall with Slits

Based on the mechanism of steel slit wall, a simplified elasto plastic analytical model which allows for nonlinear dynamic and static analysis was proposed. The parameters of simplified model related to configuration and nonlinear behavior were defined. In order to validate the simplified model, the pushover analysis of steel slit wall and a frame with steel slit wall were conducted. The results show that the load displacement curves obtained from simplified models, experiments and FEM are similar. The proposed model can fully represent the mechanism of steel slit wall, and it can correctly predict the internal forces and deformations of each member in the model.     

Slip Line Field of Plane Strain Problem Obeying the GeneralizedHoek Brown Failure Criterion

According to the characteristics of plane strain problem of elastic and plastic mechanics, the bi parametric expressions were derived for stress components satisfying the generalized Hoek Brown failure criterion. Being substituted into the static equilibrium partial differential equations, a group of first order hyperbolic pseudo linear differential equation partial differential equations was obtained. Utilizing the determinant method and proper variable transformation, the characteristic direction and the differential relation equation for the stress partial differential equations were acquired. The characteristic direction indicted that in plastic zone obliquely intersecting conjugate shear slip surfaces formed two families of non orthogonal slip lines, in which conjugate angle varied with the limit stress state and the material physical properties of Hoek Brown rock mass. Since the principal direction of the maximum principal stress was circumferential in perfectly elasto plastic surrounding rock of the plastic zone around a circular opening suffering the symmetric initial stress field, the angle between the tangential direction of slip line with the principal direction of the maximum principal stress was the function of the minimum principal stress(i.e. the radial stress). Combined with the analytical solution, the polar coordinate differential equation was derived and furthermore, the polar coordinate curve equation for the slip line was obtained.     

基于对数应变的有限变形弹塑性一致性算法

提出了与基于对数应变的精确有限变形弹塑性理论相应的一致性算法。该算法的计算结果相对于真实解具有一阶精度，且能够给出精确的应力更新公式、精确的弹塑性模量和平衡方程。最后用算例验证了此理论的正确性和算法的有效性。     

Elasto- plastic Analysis of Pressure Circular Tunnel with Liner

According to the strain nonlinear softening constitutive model having inflexion point after peak stress of practical rock and considering intermediate principal stress, the plastic zone of circular cavern with liner under the condition of uniform pressure is analyzed. The elasto - plastic boundaries both for the lining and surrounding rock are discussed. The stress distribution law is different due to the different position of elastic - plastic boundary. Based on this, different stress formulas are gained. The critical pressure caused by excavation of cavern leading to the yield zone and that caused by inner pressure leading to the yield of the liner and surrounding rock is introduced.     

A 3D Visco elasto plastic Finite Element Analysis of the Asphalt Pavement Rutting Deformation

Based on the dynamic action between vehicles and pavement, a simplified model of vehicle dynamic loading caused by surface evenness was established. This research made it possible to find a Asphalt Pavement Rutting Prediction method based on the theory of visco elasto plasticity which is the basic theory of the dynamics, and finite element method (FEM). Asphalt pavement rutting was calculated and predicted, and the factors influencing rutting were analyzed and calculated. The good agreement between the calculation results and the testing road data indicate that the rutting prediction method is reasonable and reliable.     

A visco elasto plastic creep model of outburstprone coal under triaxial compression

Using self made creep seepage experimental apparatus, triaxial creep tests on outburst prone coal are carried out with coal samples taken from Songzao Coal Mine. It is found that the attenuation creep property is shown in the conditions of less than its long term strength load, while non attenuation creep property for the greater conditions. By introducing a visco elasto plastic body which can describe the deformation property of non Newtonian fluids, the visco elasto plastic creep model of outburst prone coal is put forward combined with a Poyting Thomson model. The model parameters were fitted out with Matlab programmer and validation is employed. It is found that the test results were in good agreement with those by the proposed model.     

3D Meso scale Failure Simulation of Four phase Composite Concrete

Taking into account the influence of the internal micro cracks on the strength and deformation of concrete, a four phase composite material model was proposed, in which it included mortar, aggregate, interface and random defects. Meso scale unit in concrete was subjected to elastic plastic damage constitutive of increments form in strain space. With the simulation of mesh concrete crack growth by damage elimination, the damage processes of concrete under 3 D uniaxial compression and the elasto plastic damage process of concrete under uniaxial tension with heterogeneous specimen were obtained. It was shown that the proposed four phase model added the simulation of random defects, with which it was more appropriate to the actual situation in concrete forming. The percentage of random defects in volume was the key to determine the weakening degree of macro strength of concrete. The cracks occlusion was obvious for the lower homogeneous uniaxial tension specimen and the fracture was clearer for higher homogeneous specimen. The simulation results was in good agreement with test results.