多重因素影响下的土–岩界面剪切试验强度研究

Study on the Shear Test Strength of Soil-Rock Interface under Multiple Influencing Factors

摘要: 降雨引起的含水率急剧增长会降低土–结构界面的剪切强度。为探讨不同条件下土–结构界面的力学性能，本文开展了一系列剪切试验，分析了剪应力–位移曲线特征、法向应力、界面粗糙度及含水率对界面性能的影响。结果表明，在最佳含水率和饱和含水率下，土–岩界面的剪应力–位移曲线均表现出明显的软化特征，且随着界面粗糙度的增加，软化程度愈发明显。在同一界面粗糙度条件下，土–结构界面的剪切峰值强度和残余强度均随法向应力的增加而显著提高，法向应力被确认是影响土–结构界面剪应力–位移曲线特征的关键因素。土–结构界面的剪切强度受界面粗糙度和含水量的双重影响：当土体处于最佳含水率时，提升界面粗糙度有助于增强土–结构界面强度，而在饱和含水率下，粗糙度的增加则会降低土–结构界面强度。在高含水率和高粗糙度的双重条件下，水分的增加对土–结构界面抗剪强度具有显著的弱化效应。

Abstract: The rapid increase in moisture content caused by rainfall reduces the shear strength at the soil-structure interface. To investigate the mechanical properties of the soil-structure interface under different conditions, a series of shear tests were conducted in this paper. The effects of shear stress-displacement curve characteristics, normal stress, interface roughness, and moisture content on interface performance were analyzed. Results indicate that at both optimum moisture content and saturated moisture content, the shear stress-displacement curves of the soil-rock interface exhibit pronounced softening characteristics, with the degree of softening increasing as interface roughness rises. At the same interface roughness, both the peak shear strength and residual strength of the soil-structure interface significantly increased with rising normal stress. Normal stress was confirmed as the key factor influencing the characteristics of the shear stress-displacement curve at the soil-structure interface. The shear strength at the soil-structure interface is influenced by both interface roughness and moisture content: when the soil is at optimum moisture content, increasing interface roughness enhances soil-structure interface strength; however, at saturated moisture content, increased roughness reduces soil-structure interface strength. Under the dual conditions of high moisture content and high roughness, increased moisture exhibits a significant weakening effect on the shear strength of the soil-structure interface.