Papers by Author: Bing Rui Chen

Abstract: This paper proposes two concepts in order to estimate the stability of surrounding rockmass of deep tunnel, one is YAI (yielding approach index) which is used to denote the stability difference among the zones in surrounding rockmass whose stress states are close to yielding, the other is FD (failure degree) which focuses on the estimation of failure degree of the zones in surrounding rockmass and can be calculated by the equivalent plastic strain when failure occurs. Finally, a numerical analysis on the excavating process of a deep tunnel is performed, and YAI and FD are used to estimate the stability states of rockmass. The accurate estimation on plastic field and the proper evaluation on stability state indicate that these two concepts are rational and of perfectly practical use.

Abstract: Multiple-cable single borehole anchorages are widely used in China, accepted and regarded as a very effective method for slope protection, landslide remediation and foundation ditch support. This paper presents a new method for testing tensional stresses of individual steel strands within anchor cables in single boreholes. A rig has been designed to permit testing of cables within a single borehole, including two special features: a metal plate that distributes tension between strands of a cable and a sensing device that measures the stress in each individual strand. The feasibility of the method has been demonstrated by an in situ tensional stress test on anchor cables at a landslide remediation site that successfully measured the forces on individual steel strands fastened to different anchorage segments within a borehole. The steel cable strands displayed nonlinear extension characteristics; and the length of anchorage segments and grout strength met design criteria. The results confirm that this design of anchorage is satisfactory and can provide valuable data for future design and construction.

Abstract: In this paper, the experimental study on the mechanical property of limestone under triaxial compression with different hydrochemical environments is conducted and the non-linear characteristics of complete stress-strain process of limestone subjected to chemical corrosion, are analyzed. The behaviors of deformation and strength of limestone eroded by different chemical solutions are obtained. It is known from the experimental and analytical results that different chemical environments such as chemical composition, pH value etc can affect the mechanical property of rock differently. How to establish a multifactor characteristic constitutive model which can reflect different chemical environments is the key problem to study the coupling corrosion effect of stress and chemistry of rock. The constitutive model of evolutionary neural network for rock under chemical corrosive environments is put forward, and the neural network constitutive relationship under stress-chemistry coupling corrosion is established by applying the theory of evolutionary computation and neural network. The neural network constitutive model established in this presented paper mainly takes into account the following three aspects: chemical environments of rock specimens, content of main mineral compositions that are liable to being eroded by chemical solution, and mechanical environments. The results are in good agreement with the experimental data.