中主应力对输电线路地基土强度影响研究

Study on the Influence of Intermediate Principal Stress on the Strength of Transmission Line Foundation Soil

在静动荷载联合作用下,输电线路地基土所受到的应力路径十分复杂,同时在不同的输电线路路基上外界荷载或地形等因素也会对土体强度产生影响。为研究应力路径对土体的强度影响,文章采用空心圆柱扭剪仪(HCA)进行了一系列控制中主应力系数的定向剪切单元体试验。通过施加轴力和扭转模拟现实中的复杂路径,控制围压和中主应力系数b模拟现实中的复杂荷载情况,借此研究了不同中主应力系数和剪切角度对砂土的沉降和剪切强度的影响。研究表明:砂土的轴向破坏应力随角度的增大而减小;破坏广义剪应力随角度的增大而减小,并表现出明显的硬化;砂土的破坏广义剪应力与b值呈现负相关。

Under the combined action of static and dynamic loads,the stress path of the transmission line foundation soil is very complex.At the same time,the external load or terrain and other factors on different transmission line subgrade will also affect the soil strength.In order to study the influence of stress path on the strength of soil mass,a series of directional shear unit tests were carried out with hollow cylinder torsional shear apparatus(HCA)to control the intermediate principal stress coefficient.By applying axial force and torsion to simulate the complex path in reality,the confining pressure and intermediate principal stress coefficient b were controlled to simulate the complex load in reality,and the influence of different intermediate principal stress coefficient and shear angle on the settlement and shear strength of sand was studied.The results show that the axial failure stress of sand decreases with the increase of angle.The failure generalized shear stress decreases with the increase of angle and shows obvious hardening.The failure generalized shear stress of sand is negatively correlated with b value.