干湿循环和吸力对非饱和下蜀土力学特性影响的试验研究

Experimental study on the effects of wet-dry cycles and suction on the mechanical properties of unsaturated Xiashu loess

为研究干湿循环和吸力共同作用对非饱和下蜀土力学特性的影响,选取镇江某边坡的下蜀土为研究对象,通过非饱和直剪试验,对不同干湿循环次数及吸力水平下下蜀土力学特性的变化规律进行了研究.结果表明:随着干湿循环次数的增加,下蜀土表面裂隙明显增加并具有不可逆性;下蜀土的抗剪强度经短暂增大后逐渐降低,并在第4次干湿循环作用后趋于稳定;下蜀土的黏聚力在经历短暂提高后逐渐降低并趋于稳定,而其内摩擦角则随干湿循环次数的增加变化幅度较小,呈上下波动态势;相同干湿循环次数下,吸力的存在对于下蜀土的黏聚力具有提升作用,而对土体内摩擦角的影响则不明显.研究结果可为干湿循环作用下下蜀土边坡的稳定性分析提供计算参数,具有实际工程意义.

To study the effect of wet-dry cycles and suction on the mechanical properties of unsaturated Xiashu loess,Xiashu loess of a slope in Zhenjiang City was selected as the research soil,the mechanical properties of unsaturated Xiashu loess under different wet-dry cycles and suction conditions were studied by unsaturated direct shear tests.The results show that the fissures on the surface of Xiashu loess increase obviously and are irreversible with the increase of the number of wet-dry cycles,and the shear strength of Xiashu loess decreases after a short period of increase and tends to be stable after the 4th wet-dry cycle.The cohesion of the Xiashu loess gradually reduces and stabilizes after a brief increase,and the internal friction angle of soil mass fluctuates up and down with the increase of wet-dry cycles.Under the same number of wet-dry cycles,the existence of suction can improve the cohesion of Xiashu loess,but its influence on the internal friction angle is not obvious.The research results provide calculation parameters for the stability analysis of Xiashu loess slopes during wet-dry cycles,and thus they have practical engineering significance.