钢土接触面位移与强度特性直剪试验

Experimental study on displacement and strength behavior of interface between soil and steel using direct shear test

利用改进的直剪仪对不同密实度(40%、55%、70%、85%)的粗粒土与不锈钢毛坯板之间接触面进行直剪试验,研究粗粒土与钢板接触面之间的接触力学特性以及粗粒土相对密实度对其影响规律。结果表明:粗粒土与钢板之间的接触面在达到剪切破坏前,剪应力与剪切位移之间近似呈线性关系。接触面的抗剪强度及切向劲度系数均随着粗粒土相对密实度的增大而增大,相对密实度由40%增至85%时,接触面的黏聚力平均增大41.8%,内摩擦角平均增大35.4%;切向劲度系数ks平均增加11.2%。接触面法向应力σn从100kPa增加到800kPa的过程中,切向劲度系数ks平均增加40.3%。基于试验结果找到切向劲度系数ks与法向应力σn和相对密实度Dr之间的关系,提出ks-σn-Dr经验关系式,建立了具有简单形式的接触面本构模型。

The contact surface between the coarse-grained soil and the stainless-steel blank was tested by an improved direct shear apparatus.Four relative compactness,which is 40%,55%,70%and 85%,were used for the coarse-grained soil.The contact mechanical properties of the interface between coarse-grained soil and steel plate and the influence of relative density of coarse-grained soil are studied.The results show that before the interface between coarse-grained soil and steel plate reaches shear failure,the relationship between shear stress and shear displacement is approximately linear.The shear strength and shear stiffness coefficient of the contact surface increase with the increase of relative density of coarse-grained soil.When the relative density increases from 40%to 85%,the cohesion of the contact surface increases by 41.8%on average,the internal friction angle increases by 35.4%on average,and the shear stiffness coefficient ks increases by 11.2%on average.The tangential stiffness coefficient ks increases by 40.3%on average when the normal stressσn of contact surface increases from 100 kPa to 800kPa.Based on the test results,the relationship between the tangential stiffness coefficient ks,the normal stressσn and the relative density Dr is found,and an empirical formula of ks-σn-Dr is proposed,thus a simple contact-surface constitutive model is established.