Analysing of the Factors Affecting Pre-Stressing Losing in Pre-Stressing Cable Anchor and Recommending Compensative Measures

Abstract

After the rock bolt or cable bolt installed in rock and soil mass, as the time goes on, the pre-stress load in bolt maybe losing. Through studying and analyzing the field test data, the factors leading to pre-stress losing are both external and internal factors. The internal factors are cable steel wire loose and rock and soil mass creep deformation. In which the cable steel wire has been pre-tensioned, its affection for load losing is very little. While the rock and soil mass creep deformations have great affection to pre-stress loss. There, if the cable bolt is installed in hard rock, the rock creep deformation will be very little and the load losing in cable bolt will be very few. But if the cable bolt is installed in soft rock and soil mass, the creep deformation will be very much greater than in hard rock, and the pre-stress losing in cable bolt will be very great. The external factors are shocking load, such as blasting load, storm rainfall, temperature change and stress change of anchored rock mass. Through analyzing these affecting factors, some recommend the compensative measures which include choosing appropriate steel wire, pre-tensioning and over-tensioning cable bolt, controlling the blasting rigorous and monitoring the cable long time enough in work time.