全风化花岗岩强度特性与微观孔隙特征试验研究

Experimental Study on Strength and Microscopic Pore Characteristics of Fully Weathered Granite

以厦门市翔安区轨道交通4号线某段工程为研究对象,对全风化花岗岩样进行了三轴不排水剪切试验和核磁共振试验,分析了不同围压下全风化花岗岩样的强度变化规律和加载前后全风化花岗岩样的孔隙大小、孔径分布变化特征。研究结果表明:岩样的剪切强度随围压的增大而增大,且随着围压差值的增加,剪切强度增加幅度也呈增大的趋势;不同围压作用下孔隙水压力的发展情况较为一致,均呈“急剧上升—缓慢减小—趋于稳定”的规律;围压与岩样的平均孔径近似呈线性分布,且岩样的平均孔径随围压的增大而增大;荷载作用下全风化花岗岩样内部孔隙结构发生重新排列,表现为大孔隙转化为小孔隙;岩样的平均孔径与轴向应变之间存在负相关性。该研究成果可为宏、微观理论的研究提供一定参考。

In this paper,a project section of Rail Transit Line 4 of Xiang’an District,Xiamen city,is taken as the research object.The triaxial undrained shear test and the nuclear magnetic resonance test are carried out on the fully weathered granite.The strength variation law of fully weathered rock samples under different confining pressures and the pore size and pore size distribution of fully weathered granite before and after loading are analyzed.The research results show that the shear strength of the rock sample increases with the increase of the confining pressure.With the increase of the confining pressure difference,the increase of the shear strength also increases;The development of pore water pressure under different confining pressures is relatively consistent,and they all show the law of“rapid increase-slow decrease-tend to be stable”;The confining pressure and the average pore diameter are approximately linearly distributed.The average pore diameter of the rock sample increases with the increase of the confining pressure;Under the action of loading,the internal pore structure of the fully weathered granite samples rearranged which showing that the large pores transformed into small ones;There is a negative correlation between the average pore diameter and the axial strain.The research results can provide some reference for the research of macro and micro theory.