广州地区花岗岩残积土抗剪强度及其影响因素试验研究

Experimental Research for Shear Strength and Influencing Factors of Granite Residual Soil in Guangzhou Area

依托广州地铁科研项目,以广州地区花岗岩残积土为研究对象,进行了一系列室内直剪试验,分析了试验中剪切速率、加载级数和破坏值选取的综合影响。试验结果表明,花岗岩残积土的室内直剪剪切速率为0.8 mm min最能反映原状土的强度性质;在花岗岩残积土室内试验测试土体强度时,三级加载方式最为合理;破坏值应当按规范选取,即:剪切位移4 mm之前,剪应力出现峰值,则破坏值选峰值;若剪切位移4 mm之前,剪应力未出现峰值,则破坏值选剪切位移4 mm所对应剪切应力。同时通过室内直剪试验和三轴试验结果进行了对比分析,得出室内直剪试验比三轴(UU)试验测得土的抗剪强度普遍偏大。

Based on the scientific research project of Guangzhou metro,a series of indoor direct shear tests are carried out on the granite residual soil in Guangzhou area,and the comprehensive influence of the shear rate,loading series and failure value in the test is analyzed. The test results show that the indoor shear rate of 0.8 mm min can reflect the strength properties of the original soil,and the three stage loading method is the most reasonable in the test of soil strength in the granite residual soil test,and the failure value should be selected according to the standard,that is,the shear stress appears to be peak before the shear displacement is 4 mm. The peak value of the failure value is chosen.If the shear stress does not peak before the shear displacement 4 mm,the shear stress of shear displacement 4 mm is chosen for the failure value. At the same time,through the comparison and analysis of the results of the indoor direct shear test and the three axis test,it is concluded that the shear strength of the indoor direct shear test is generally larger than that of the three axis（UU） test.