常偏应力路径下花岗岩风化土的力学特性

Mechanical Properties of Weathered Granite Soil Under Constant Deviatoric Stress Path

为了探究不同围压下花岗岩风化土力学特性性能,选取广西玉林市容县花岗岩风化土作为研究对象,通过对饱和重塑花岗岩风化土进行常偏应力排水剪切(CSD)试验,研究了不同围压下风化土的力学行为过程和破坏机理,并对CSD试验后的试样进行了扫描电镜(SEM)试验,揭示了CSD试验下风化土失效的微观机理。结果表明:在孔压上升初期,试样的轴向应变增长缓慢,偏应力几乎不变;随着孔压的不断升高,平均有效应力下降至失稳点,轴向应变突然增加,偏应力迅速衰减,试样呈现出瞬变破坏的形式;在降雨入渗时,围压程度的变化对土体行为有显著影响,低围压下,试样局部水压力增大,导致鼓胀破坏。而高围压下,试样呈现伴随有软弱面的剪切破坏。

In order to explore the mechanical properties of granite weathered soil under different surrounding pressures,the granite weathered soil of Rong County in Yulin in Guangxi was selected as the research object.The mechanical behavior process and damage mechanism of the weathered soil under different surrounding pressures were studied through constant shear drained(CSD)test of the saturated reshaped granite weathered soil.In addition,scanning electron microscopy(SEM)tests were performed on the samples after the CSD test,revealing the microscopic mechanism of the failure of weathered soil under the CSD test.The results show that in the early stage of the pore pressure rise,the axial strain of the sample grows slowly,and the partial stress is almost unchanged.As the pore pressure continues to increase,the average effective stress drops to the instability point,the axial strain suddenly increases,the partial stress decays rapidly,and the sample shows the form of transient damage.During the infiltration of rainfall,the change in the degree of surrounding pressure has a significant impact on the soil behavior.At low surrounding pressure,the local water pressure of the sample increases,resulting in bulging and destruction;at high surrounding pressure,the sample exhibits shear damage accompanied by weak surfaces.