干湿循环下花岗岩残积土抗剪强度试验研究

Experimental Study on Shear Strength of Granite Residual Soils Subjected to Drying-wetting Cycles

近年来,随着我国城镇化战略的加速推进,高速公路、铁路、隧道等工程建设大规模开展。工程项目的建设离不开边坡支护,在暴雨条件下边坡失稳风险骤增,极易造成经济损失和人员伤亡。为揭示暴雨下边坡失稳机制,以我国粤港澳大湾区典型花岗岩残积土为研究对象,通过开展干湿循环模拟试验和常规小型直剪试验,深入探讨干湿循环作用下花岗岩残积土抗剪强度弱化规律和弱化累积效应。以花岗岩残积土抗剪强度作为边坡稳定性主要影响指标,重点分析了土体黏聚力和内摩擦角的变化规律。试验结果表明:随着干湿循环次数的增加,不同饱和度下花岗岩残积土的黏聚力均呈现较明显的减小趋势,其摩擦角则在一定范围内浮动改变,但大致稳定。研究结果拓展了复杂的水土作用对花岗岩残积土强度的影响,阐述了干湿循环下花岗岩残积土强度衰减变化规律,对暴雨下边坡全寿命安全评估具有一定的指导作用。

In recent years,as the urbanization in China is accelerating,large-scale construction of highways,railways and tunnels develop rapidly.The construction of engineering projects is inseparable from the protection of slopes.The accidents caused by slope failures subjected to rainstorm conditions not only bring losses,also cause casualties.To study the failure mechanism of slopes throughout the life cycle,carries out drying-wetting cycles tests and direct shear tests using the typical Granite residual soils in the Guangdong-Hongkong-Macao Greater Bay Area of China.The strength weakening and cumulative effect of Granite residual soils under drying-wetting cycles are investigated.The shear strength of the Granite residual soils,reflected by the cohesion and internal friction angle,is taken as the main factors affecting the slope stability.Experimental results reveal that with the increasing of drying-wetting cycles,the cohesion of the granite residual soils obviously tends to decrease under various saturation degrees,while the friction angle fluctuates within a certain range and is roughly stable.The research results expand the influence of complex water and soil interactions on the Granite residual soils,comprehensively explain the strength weakening effects under drying-wetting cycles,and are helpful for safety assessment of slopes.