高应力下粗砂-结构接触面颗粒破碎影响因素试验研究

Experimental Study on Influencing Factors of Particle Breakage of Coarse Sand Structure Interface under High Stress

为了研究高应力下粗砂与结构接触面的剪切破碎影响因素,采用改装后的RMT-150B试验系统的直剪试验仪进行接触面直剪试验,对高法向应力作用下含水率为0%,8%,16%,24%的粗砂与具有4种不同粗糙度、强度混凝土基底的接触面直剪试验结果进行了分析,结果表明:基底硬度增大,基底硬度与相对破碎率关系曲线趋于下降趋势,相对破碎率减小;相对破碎率随着含水率增加而增加,随粗糙度的增加破碎量减小;法向应力对颗粒破碎影响明显,相对破碎率的增大速率也表现出随法向应力增大而增大的趋势。保持含水率不变,法向应力与颗粒破碎曲线规律性较好;保持基底硬度和接触面粗糙度不变,法向应力与颗粒破碎关系较为离散,总体保持颗粒破碎随法向应力增加而增加。进行方差分析表明:接触面粗糙度对粗砂-混凝土结构接触面剪切破碎的影响较显著;法向应力、基底硬度与含水率对结构接触面剪切颗粒破碎的影响均特别显著,显著性从大到小依次为:砂的含水率、基底硬度、法向应力、接触面粗糙度。针对不同试验所得到的法向应力对颗粒相对破碎率影响规律进行讨论,认为:从零法向应力开始,随法向应力的增大相对破碎率增加速率增大,当剪切应力达到集中段颗粒抗剪破强度后,相对破碎率增加速率随法向应力增加而减小。

In order to study the influencing factors of shear fracture of interface between coarse sand and structure under high stress, the direct shear test on the interface is carried out by using direct shear tester modified from RMT - 150B testing system. The direct shear test result higher of the interface between the coarse sand with water contents of 0%, 8%, 16%, 24% and the concrete base with 4 roughnesses and strengths under higher normal stresses are analysed. The result shows that ( 1 ) as the base hardness increases, the relation curve of base hardness and relative breakage rate tends to decrease, the relative breakage is reduced;(2) the relative breakage rate increases as the water content goes up, while breakage quantity decreases as the roughness increases;(3 ) the normal stress has a significant effect on the particle breakage, and the increase rate of the relative breakage rate also shows a tendency to increase as the normal stress increases. Keeping the water content constant, the normal stress and the particle fracture curve are regular;(4 ) keeping the hardness of the base and the roughness of the contact surface constant, the relationship between the normal stress and the particle breakage is relatively discrete, and the overall particle breakage increases with the increase of the normal stress. The variance analysis shows that (1 ) the roughness of the contact surface significantly influences the shear breaking of the coarse sand-concrete structure contact surface;(2) normal stress, base hardness and water content all present significant influence on the shearing grain breakage of the structure contact surface, and the order of significance is: moisture content of sand, base hardness, normal stress, and roughness of the contact surface. According to the influence of the normal stress obtained by different experiments on the relative breakage rate of the particles, it is concluded that from zero normal stress, the relative breakage rate increases with the increase of normal stress, while it decreases with the increase of normal stress when the shear stress reaches the shear strength of particles in the concentrated section.