砂性土宏细观强夯加固机制的试验研究

 通过自行设计的可视室内强夯模型试验仪，借助于图像跟踪拍摄和数字处理技术，对夯击作用下砂性土密实的宏细观机制进行试验研究，得到不同夯击次数下砂土位移等值线图和动接触应力时程曲线等宏观力学响应；分析夯击后砂土颗粒的定向性和平均配位数等细观特征变化。试验结果表明，砂性土强夯加固的单遍最佳夯击次数宜为8击左右，其加固机制宏观上表现为地面变形不断发展，细观上是一个颗粒从无序排列到定向排列、颗粒与颗粒之间接触数不断增加的过程。研究结果对强夯法的设计与施工具有一定指导意义，也为研究冲击荷载作用下土体宏细观力学响应特性提供一条新的思路。

EXPERIMENTAL RESEARCH ON MACRO-MESO CONSOLIDATION MECHANISM OF SANDY SOIL WITH DYNAMIC COMPACTION

A fundamental understanding of the macro-meso mechanism of dynamic compaction of sandy soils using a modified visible model test apparatus，which is designed by authors，is carried out. A series of model tests of dynamic compaction are conducted on sandy soil with a new technique for real-time visualization and photographing；and soil displacement and dynamic stress are monitored for each case. The experimental results show that the technique can be used successfully to visualize the meso-scale change of sand grains fabric including orientation and average coordination apart from displacement. It is found that the optimum hitting number of each pass is about 8 for sandy soils；and the macro-mechanical results of dynamic compaction are the increase of ground displacement and decrease of void ratio；and the meso-scale mechanism is the process of grains rearrangement from disorder to orientation and increase of average coordination. The findings of this study will be beneficial to the innovation and determination of parameters for dynamic consolidation and the research of macro- meso response under impact loading.