波浪荷载作用下压实钙质砂强度与变形特性及微观机理研究

Considering the rapid increase in demand for resource exploitation and defense construction in the islands of South China Sea and the mechanism of strength and deformation characteristics of calcareous sand under wave loading was undefined so far, this project concentrates on the law of strength and deformation development of compacted calcareous under wave loading by taking three kinds of undrained tests including fixed principal stress axes, cyclic rotation of principal stress axes with magnitudes of principal stresses kept constant, and cyclic changes of principal stresses in both their axes and magnitudes with dynamic hollow cylinder apparatus. The research focuses on the quantitative analysis of relation between distribution characteristics of particle morphology and contacting mechanics of calcareous by using nano-CT scanner, atomic force microscope scanner, intergranular friction tester and single particle compression testing instrument. Based on particle flow theory and combining with laboratory test results to illustrate the mechanism of strength and deformation mechanisms of calcareous sand under wave loading, and to provide scientific basis for the feasibility of using calcareous sand as foundation backfill material and stability analysis of engineering foundation.

本项目以南海诸岛资源开发和国防建设的迫切性为背景，从波浪荷载作用下钙质砂强度与变形特性机理尚不明确这一深刻问题出发，以人工压实后的钙质砂为试验对象，采用空心圆柱扭剪仪对其进行主轴固定单调剪切不排水试验、纯应力主轴循环旋转不排水试验及主应力幅值与应力主轴耦合循环变化的不排水试验，明确波浪荷载作用下压实钙质砂强度与变形发展规律；以钙质砂颗粒个体为研究对象，利用nano-CT扫描仪、原子力显微镜扫描仪、粒间摩擦力测试仪以及单颗粒压缩仪等微细观测试仪，定量分析钙质砂颗粒形态分布特征与颗粒接触力学参数关系，构建钙质砂颗粒形态特征参数分布方程以及反映颗粒形态特征的颗粒接触力学参数分布方程，揭示颗粒接触微观机理；在此基础上，基于颗粒流理论，结合室内试验结果，阐明钙质砂在波浪荷载作用下的强度与变形机理，为钙质砂作为珊瑚礁地区地基回填材料的可行性及地基稳定性分析提供科学依据。