含水量变化对广州花岗岩残积土抗剪强度的影响

Water Content Variation on the Mechanical Characteristics of Granite Residual Soil in Guangzhou

基于不固结不排水直剪试验,建立了广工大学城区域花岗岩残积重塑土关于含水率与抗剪强度指标之间的试验曲线。试验研究表明:在控制相同含水量与干密度条件下,对花岗岩残积原状土和重塑土进行了不固结不排水直剪试验,当垂直压力小于先期固结压力时,重塑土的粘聚力小于原状土的粘聚力,重塑土的内摩擦角也小于原状土的内摩擦角;当垂直压力大于先期固结压力时,两者的抗剪强度逐渐接近,且在垂直压力大于135 kPa之后,原状土的抗剪强度小于重塑土的抗剪强度,此时重塑土的内摩擦角大于原状土的内摩擦角。在不同含水量的花岗岩残积重塑土不固结不排水直剪试验中,土体的抗剪强度均随垂直压力的增大而增大;土体的黏聚力随含水率的增加而显著减小,而内摩擦角随含水率的增加而稍微减小。

The unconsolidated-undrained direct shear tests were carried out on the undisturbed and remolded granite residual soil samples,and the test curves between the moisture content and shear strength of the granite residual remolded soil in Guangdong University of Technology area were obtained.The experimental results show that,under the same water content and dry density,when the vertical pressure is less than the initial consolidation pressure,the cohesion of the remolded soil is less than that of the undisturbed soil,and the internal friction angle of the remolded soil is also less than that of the undisturbed soil.When the vertical pressure is greater than the initial consolidation pressure,the shear strength of the remolded soil is gradually close to that of the undisturbed soil;as the vertical pressure is greater than 135kPa,the shear strength of the undisturbed soil begins to be smaller than that of the remolded soil,and the internal friction angle of the remolded soil is larger than that of the undisturbed soil.In the comparison of the unconsolidated-undrained shear tests of granite residual remolded soil with different water content,the shear strength of soil increases with the increase of vertical pressure,the cohesion of remolded soil decreases significantly with the increase of water content,while the internal friction angle decreases slightly with the increase of water content.