Papers by Author: Tao Xu

Abstract: In this paper, the stress and strain distribution in coal seam and fault edge under various fault dips is numerically simulated to study the stability of the barrier pillar and determine the reasonable length of coal seam mining using COMSOL Multiphysics package. Numerical simulations show that remarkable increase in stress around fault edge when coal seam is about 250 m away from the fault with a smaller fault angle and the stability of fault is seriously affected by the mining excavation. While the obvious increase in stress around fault edge can be observed until coal seam is about 200 m or 150 m away from the fault with a larger fault angle and the stability of fault is seriously affected by mining excavation. Numerical results indicate that the larger the fault dip is, the larger the reasonable mining length in coal seam where a fault near coal seam exists. Moreover, the fault with smaller dip is more easily activated to induce the failure of the fault and the occurrence of water inrush in coal mining. To prevent the occurrence of fault failure accident, we need to study the reasonable mining length of coal seam, to ensure the safety production and increase the recovery ratio of coal.

Abstract: Numerical simulations the different rock sample in the uniaxial compression have been conducted using Rock Failure Process Analysis program (RFPA^2D) to evaluate the effects of joint trace lengths on the overall mechanical behaviour of jointed rock masses in this paper. Numerically simulated stress-strain curve, peak stress, peak strain and failure patterns were compared with the corresponding experimental results. We found that for a series of partially-spanning joint geometries with the same joint orientation, the projected area will be proportional to the square of the trace length. Thus, the relationship between compressive strength and partially-spanning joint geometry for the tests carried out to explore the influence of joint trace length may be expressed as a linear correlation between compressive strength and projected area.Numerical simulations agree well with experimental results.

Abstract: Stability analysis of steep rock bedding slope with weak structure planes using strength reduction method was simulated in this paper. The post processing function can display the development condition of the plastic zone, which is the criterion for instability of the slope. Analysis with working conditions of natural circumstance, after excavation, and the slope reinforced by anchor shank after excavation were put forward. Failure modes and safety coefficients of the slope proved that weak plane is the main factor controlling slope failure. Simulation results shown that strength reduction method is appropriate in predict the shape and position of the potential failure surface of steep rock bedding slope.

Abstract: Based on the fluid-solid coupling theory, we describe the fractured rock mass as a continuous porous medium and consider the rock mass permeability coefficient a function of the stress and strain. By using the multi-physics coupling analysis software COMSOL, we achieved the dynamic change of permeability coefficient, and found that serious damage due to micro cracking occurred in the excavated damage zone of rock mass due to the yield and failure of rock mass. Corrodingly, permeability will remarkably increase, which is basically consistent with the experimental results. The simulations indicated the "indirect coupling" effect of seepage and stress. Therefore, the coupled analysis of the seepage and stress in fractured rock masses is important for the practical rock mechanics and rock engineering.

Abstract: The mechanical properties of rock experiencing the variation of joint orientation under uniaxial compression condition were simulated in this paper. Numerical simulations on rock sample in uniaxial compression have been conducted to evaluate the effects of joint orientation on the overall mechanical behaviour of jointed rock masses. It was done using the Rock Failure Process Analysis program RFPA^2D. Numerically simulated stress-strain curve, peak stress, peak strain and failure patterns were compared with the corresponding physical tests. Numerical simulations agree well with physical results, it is shown that RFPA^2D is suitable for the analysis of joint orientation effect on rock fracture.

Abstract: Steel truss bridge is an important part of transportation hub and lifeline engineering, it recently has attracted more attention on dynamic performance of steel truss bridge. In this paper, the ANSYS software is used to perform the modal analysis of steel truss bridge, and we find that the main bridge are more sensitive to the vertical earthquake (i.e., Y direction). In the earthquake response spectrum analysis on Y direction, we find that the maximum deformation is at mid-span of steel truss bridge. In the transient analysis of seismic waves, under the action of horizontal and vertical earthquake accelerations, the structure displacement dynamic diagram and time-history displacement curve are obtained and some conclusions are drawn.

Abstract: Based on the fluid-solid coupling theory, we study the stability of surrounding rock mass around underground oil storage in Huangdao, Shandong province, analyze the stress of the surrounding rock mass around three chambers and the displacement change of several key monitoring points after excavation and evaluate the stability of surrounding rock mass using COMSOL Multiphysics software. Research results show that the stress at both sides of the straight wall of cavern increases, especially obvious stress concentration forms at the corners of the cavern, and the surrounding rock mass moves towards the cavern after excavation. The stress and displacement of the surrounding rock mass will increase accordingly after setting the water curtains, but the change does not have a substantive impact on the stability of surrounding rock mass.

Abstract: The mechanical properties of granite experiencing high temperatures under uniaxial compression condition were simulated in this paper. Numerically simulated stress-strain curve, peak stress, peak strain and the tangent elastic modulus were compared with the corresponding physical tests. Simulated results agree well with physical tests results, it is shown that Abaqus is suitable for the analysis of the temperature effect on rock fracture.

Abstract: The principle of the structure of displacement function, the establishment of governing equations, level set method were briefly outlined in this paper. Numerical simulations on three dimensional single edge notched specimens with different crack length in tension were performed using Abaqus software based on extended finite element method (XFEM), the stress intensity factor at static crack front was analyzed and the simulated results were in good agreement with analytical solutions. Numerical simulations in the present paper indicated that the extended finite element method is very suitable to deal with nonlinear fracture problems.

Abstract: In this paper, the bond length effect of FRP plate on bonding performance and the distribution patterns of the stress in FRP plate was investigated using 3D Realistic Failure Process Analysis (RFPA^3D) code to study the debonding mechanism of the FRP plate bonded to concrete block. Numerical simulations show that the progressive debonding of FRP plate bonded to concrete occurs in the concrete on the condition of different bond lengths can be divided into four stages: elastic-deformation stage, elastic-softening stage, elastic-softening-debonding stage and softening-debonding stage. It is also show that the interfacial bond strength and the global slip of FRP-to-concrete increase with the increase of the bond length.