植物根系固土护坡抗剪强度试验研究

Experimental research on improving shear strength in slope protection by plant root system

以全风化花岗岩残积土为研究对象,通过对加入狗牙根根系形成的根土复合体在不同含水率条件的室内直剪试验,研究了土壤含水率及含根量对抗剪强度的影响,用以评价植物根系对全风化花岗岩残积土坡的加筋效应及固坡效果.结果表明:植物根系可以显著增强土体的抗剪强度,促进边坡的稳定;根土复合体的抗剪强度随着含水率的增加而降低;随着含根量的增加,根土复合体的抗剪强度增强,主要表现在粘聚力c随含根量增加而显著增大,内摩擦角φ值几乎不变;当含根量达到0.3%及以上时根土复合体的抗剪强度增幅有所减缓,即存在最优含根量区域;根系对25%含水率的土体加筋效果最显著.

Taking completely decomposed granite eluvial soil as the research object, this paper analyzes the impacts of moisture content and root weight on shear strength through direct shearing tests for the investigation of plant root system distributing along vertical profile in order to evaluate the reinforcement effect of completely decomposed granite eluvial soil slope. The results show that： plant root system can significantly increase shear strength of soil and promote the stability of the slope; shear strength of root-soil composite decreased with increasing moisture content; shear strength of root-soil composite increased with increasing root weight, mainly displayed in the obvious increasing cohesion（c ）with increasing moisture content, but internal friction angleФ was almost the same. When root weight reached 0.3 % or more, increasing amplitude of root-soil composite shear strength slowed, which means there exists an optimal root weight area. Reinforcement effect of the soil with 25 % moisture content has the most significant effect under the plant root system.