DEFORMATION CHARACTERISTICS OF FRACTURED WEAK ROCKS

In this paper a u-t curve for the whole process of deformation of the fractured weak rocks during all-section excavating is described from the data of in-situ successive monitoring and measurement for more than ten years, the deformation rate, amount and their effects in time and space are suggested, and the effects of main factors, such as the engineering geological properties, burial depth, opening diameters, excavation modes and in-time supporting, on the deformation characteristics of rocks are discussed. Then the criteria for division and discrimination of stability behaviors of rocks, principles for prediction of instability risk, critera for controlling deformation, principles for determining early support resistance and for selecting optimum period of late supporting, and rational excavation mode are proposed for specific engineering project.