A Study On Characteristics And Some Engineering Problems Of Granite Residual Soil With Structural Nature

The granite residual soil (GRS) is widely distributed over South of China,as development of capital construction,its engineering problems in groundworks and slopes are increasingly stand out as result of lack of knowledge on its structure nature. In this paper,based on damage mechanics, the structural damage reason for the GRS unusual physic & mechanic character of "macro-void ratio,high compressibility vs. high strength"was investigated for the first time,main results of the studies as follows. On theoretical studies,a physical model for unpuzzling the microstructure damage of GRS and the determination means for the damage factor of the elastoplastic damage model were put forward with exploration;The classification principle and criterion for GRS were examined and investigated comprehensively, and then, a new classification method for GRS was constructively brought forward;After a series of confined compression tests and dead-load in-situ tests in a engineering project were carried out for GRS, comprehensive and systematic researches were launched on the compressibility effect on GRS caused by same damage factors such as lateral stress unloading, dry shrinkage, saturation;The disintegration test in water for several GRS samples with different disturbance were launched with a simple self developed device, the mechanism on disintegrating process which was divided into three stages of surface, structure and dissolution disintegration was put forward;After affecting factors on the shear strength and structure natures of GRS were analyzed, the conclusion was advanced that the effect of disturbance damage on GRS structure mainly results in a decrease in the cohesive force of GRS, which were demonstrated by shear box and triaxial shear tests. And the method on correcting cohesive force with the e-logp curve was brought forward experimentally. On studies in engineering problems,GRS circle-jet-mixing compound pile foundation was studied by an engineering project in Xiamen city in Fujian province for the first time. After tried time after time, the innovative technics so-called "water & cement grout separated method"was brought forward, and the rather ideal result was achieved in the engineering project eventually. The four types of composite sliding surfaces for GRS cutting slopes was summed up and advanced for the first time, and the software for analyzing slope stability and designing protective structures which can consider the effect of structural surfaces have been designed and developed, which was verified by some engineering examples. Based on disturbance damage point of view, a new measure for protecting and reinforcing GRS cutting slopes has been exploratory put forward.