植被根系固土抗剪强度试验研究

通过对培养的黑麦草加固黏土原状土样进行直剪试验,研究了根系含量和含水率对加固土体抗剪性能的影响,并结合研究结果对其作用机理进行分析。试验结果表明:随根系含量增加,加固土体的抗剪强度和黏聚力逐渐增强,内摩擦角变化较小。这是因为根系的存在加强了土颗粒之间的摩擦,同时在剪切过程中根系发生弹性形变,其内部产生的拉应力通过摩擦力转化为阻碍土体位移的力,增强土体强度。随着含水率的增加,加固土体的抗剪强度和黏聚力均减小,内摩擦角变化不大。这是由于一方面水的存在使根系的拉拔阻力和土颗粒之间的摩擦阻力减小,另一方面含水率的增加导致基质吸力减小,使土颗粒之间的液桥强度降低,从而降低了土体的抗剪强度。

Experimental Study on the Shear Strength of Soil Consolidation by Root of Vegetation

In this paper,a series of direct shear tests were carried out on cultivated ryegrass-reinforced undisturbed clay,the effects of root content and water content on shear strength properties of reinforced clay were studied comparatively,and the mechanism was analyzed according to the research results. The test results show that with the increase of root content,the shear strength and cohesion of reinforced soil gradually increase,and the change of internal friction angle is slight. This is induced by the presence of roots which strengthen the friction between soil particles. Moreover,the root elastic deformation occurs in the process of shearing,and the internal tension stress of root is transformed into the force that resists the displacement of soil by friction. It is therefore the strength of soil is enhanced. With the increase of water content,the shear strength and cohesion of the reinforced soil decrease,and the internal friction angle changes little. This can be attributed to that,on the one hand,the presence of water reduces the pull-out resistance of roots and the friction resistance between soil particles,and on the other hand,the increase of water content leads to a decrease of matrix suction,which reduces the strength of liquid bridge between soil particles,thus reducing the shear strength of soil.