土石混合料-土工织物界面剪切特性研究

Study on Shear Characteristics of Soil-rock Mixture-geotextile Interface

土石混合料加筋结构常见于高填方边坡工程中,其稳定性受筋土界面相互作用的影响。为了研究土石混合料-土工织物界面的相互作用机理,利用了室内大型直剪仪进行一系列直剪试验,分析了5种含石量(0%、25%、50%、75%、100%)、3种压实度(88%、92%、96%)以及3种竖向应力(100、200、300 kPa)对界面剪切特性的影响,并建立了界面剪胀系数的经验公式。结果表明:界面在低含石量(0%~25%)下表现出剪切软化趋势,在高含石量(50%~100%)下表现出剪切硬化趋势,且剪切应力-剪切位移曲线出现较为明显的波动现象;界面最大竖向位移随含石量和压实度的增大呈现出增大趋势,随竖向应力的增大呈现出减小趋势。界面摩擦角在低含石量下基本保持稳定,而后随含石量的增大表现出先增大后减小的趋势;界面似黏聚力的增长速率随压实度的增大而减小;结合含石量、竖向应力等因素,建立了剪胀系数经验公式,该公式能够较为准确地描述界面的体积变化情况。

The reinforced structure of soil-rock mixture is commonly used in high-fill slope projects,and its stability is influenced by the interaction of the reinforcement-soil interface.In order to analyze the interaction mechanism of soil-rock mixture-geotextile interface,a series of direct shear tests were carried out by using large-scale direct shear apparatus.The effects of five kinds of rock content(0%,25%,50%,75%,100%),three kinds of compactness(88%,92%,96%)and three kinds of normal stress(100,200,300 kPa)on the interface shear characteristics were investigated,and the empirical formula of the interface dilatancy coefficient was established.The results show that the interface exhibits shear softening under the low rock content(0%-25%),but exhibits shear hardening and shear stress fluctuation obviously when the rock content is high(50%-100%).The larger the rock content and compactness,the larger the maximum vertical displacement of the interface,while the larger the normal stress,the smaller the maximum vertical displacement of the interface.The interfacial friction angle is basically stable under low rock content condition.With the increase of rock content,the interfacial friction angle first increases and then decreases.With the increase of compactness,the growth rate of interface apparent cohesion decreases.Combined with factors such as rock content and vertical stress,the empirical formula of dilatancy coefficient is established,which can accurately describe the volume change of interface.