花岗岩残积土作为一种广泛分布于中国东南沿海地区的特殊土,其特性易受水影响从而诱发灾害。为研究花岗岩残积土-土工织物界面的剪切特性,通过室内大型直剪仪,分析不同含水率(12%、16%、20%、24%)和不同竖向应力(50 kPa、100 kPa、150 kPa、200 kPa)等因素对界面抗剪强度参数的影响；并建立离散元模型,揭示不同含水率条件下花岗岩残积土-土工织物界面在剪切过程中的细观机理。研究表明:界面抗剪强度和界面摩擦角随着含水率的增加呈下降趋势,而似黏聚力随着含水率的增加先增后减,在含水率为16%时达到最大值。数值模拟结果表明,剪切带呈条带状分布于织物上方,随着剪切的进行上盒颗粒位移场逐渐规律,剪切带厚度也逐渐增大；上下盒力链由于中间织物的存在无法贯通,不同含水率条件下法向接触力、切向接触力主方向相同；能量主要通过滑移损耗,且土与织物的能量损耗远小于土与土颗粒。

As a special soil widely distributed in the southeast coastal areas of China, granite residual soil is greatly influenced by water, leading to significant changes in its mechanical properties and an increased susceptibility to disasters. To investigate the shear characteristics of the granite residual soil-geotextile interface, the effects of different moisture content (12%, 16%, 20%, 24%) and vertical stresses (50 kPa, 100 kPa, 150 kPa, 200 kPa) were analyzed through large-scale direct shear tests conducted indoors. Based on the findings of indoor experiment, the PFC2D model was established, to reveal the meso-mechanism? behavior of the granite-residual soil-geotextile interface under varying moisture content conditions during the shear process. The results revealed that the interfacial shear strength and friction angle decreases with the increasing moisture content, while the similar cohesion increases first and then decreases, reaching the maximum value at 16% moisture content. Numerical simulation demonstrated that the shear zones are distributed in strips above the fabric, and the thickness of the shear bands increases in a predictable manner with the displacement field of the particles in the upper section.? The presence of the fabric prevents the penetration of force chains between the upper and lower sections, and the primary directions of normal and tangential contact forces remain consistent under different moisture content conditions. Energy dissipation mainly occurs through slip, with the loss of energy between the soil and fabric significantly lower than that between soil particles.

国家自然科学(52378355) ,国家自然科学(52078285)