Study And Application On Lateral Shear Distribution Law Of Prestressed Anchor Cable

In this subject study of prestressed anchor cable lateral shear distribution law, based upon intensive study of theoretical analysis, numerical analysis and in-situ observations etc., series of significant research findings were gained in the essay, which were as follows:(1)According to the nonlinear unified strength criterion which considered the effect of intermediate principal stress and the nonlinear qulity of rock strength, the limit equilibrium principle and the shape of rapture of surface, the ultimate pullout force of prestressed cables in underground chambers could be calculated by the obtained equation which taked into account rock types, unconfined compressive strength of rock, dip angle and cable grouting pressure.(2)According to the situation of field pull-out test and the results of numerical simulation with the software of FLAC3D, the effect of cable bonding length on prestressed anchor cable lateral shear distribution was obtained, which were as follows:the ultimate side resistance of cable gradually increased with the increase of bonding length; the shear distribution form along the cable-rock Interface showed a nonlinear relationship, with the maximum value at the the point of intersection of free section and anchored section, and gradually decreased with the depth, reaching the value of 0 at the point between 2m and 3 m.(3)Based on the results of numerical simulation, the effect of surrounding rock strength on prestressed anchor cable lateral shear distribution was obtained, which were as follows:when the rock was softer, that is, the elastic modulus of rock body was lower, the ultimate side resistance of the cable-rock Interface was lower, with a larger and uniformer distribution zone; conversely, when the rock was harder, the ultimate side resistance of the cable-rock Interface was higher, with a smaller and concentrating distribution zone.(4)The results of on site test showed that when the rock body surrounding the bonding section had relatively superior integrity and homogeneity, the bonding strength between cement paste and borehole wall mainly depended on the roughness degree of hole wall; the interfacial debonding was the common failure mode of prestressed anchor, which behaved as the pull-out of steel strand from cement paste。(5)The study of on-site test and finite difference analysis verified the important effect of anchor cables layout density on the side resistance, which were as follows:with the decrease of cables layout density, the ultimate side resistance gradually increased and the compressive stress area of single cable gradually closed to each other to be united as one body with the mutual superposition, making the zero-stress area disappeared and increasing the supporting capacity.