澳门地区全风化花岗岩抗剪强度指标的取值

Determination of Shear Strength Index of Completely Decomposed Granite in Macao

以澳门地区31组全风化花岗岩(CDG)的基本物理指标和三轴固结不排水剪试验数据为依据,分析全风化花岗岩的剪切特性和抗剪强度指标的取值。试验结果表明,澳门地区全风化花岗岩应力–应变曲线总体呈应变软化型,孔隙水压力在最大偏应力出现前达到峰值后开始下降,随着黏粒含量的减少下降速度加快,最终可能出现负值。剪胀问题导致澳门地区全风化花岗岩的剪切强度破坏标准不能仅以主应力差的峰值一种方式取值,总结了3种取值方式,并将黏粒含量作为剪切强度取值的指导性指标,为全风化花岗岩选取强度参数提供新的思路,对提高取值的可靠性有一定帮助。

Based on the basic physical parameters and triaxial consolidation undrained shear test results of 31 groups of com-pletely decomposed granite(CDG)in Macao,the shear characteristics and the value of the shear strength index of completely decom-posed granite were analyzed.The test results show that the stress-strain curve of the completely decomposed granite in Macao is gener-ally strain-softening,the pore water pressure reaches a peak before the maximum deviatoric stress occurs and then begins to decrease,with the decrease of the clay content,the rate of decrease accelerates,and eventually a negative value may appear.It is inappropriate to take the peak value of the principal stress difference as the shear strength failure standard of Macao completely decomposed granite be-cause of the shear expansion problem.3 value methods were summarized,and the clay content was selected as a guiding index for the value of the shear strength.A new idea is provided for the selection of strength parameters of completely decomposed granite and is helpful to improve the reliability of the value.