珠海海积软土剪切带微观结构试验研究  

Microscopic investigation on shear band of marine clay in Zhuhai,China

作　　者：蒋明镜[1,2] 彭立才 朱合华[1,2] 林奕禧 黄良机 

机构地区：[1]同济大学地下建筑与工程系,上海200092 [2]同济大学岩土及地下工程教育部重点实验室,上海200092 [3]珠海市建设工程质检站,广东珠海519015

出　　处：《岩土力学》2010年第7期2017-2023,2029,共8页Rock and Soil Mechanics

基　　金：国家自然科学基金项目(No.50679057);上海市浦江人才计划项目(No.06PJ14088);国家教育委员会留学回国人员基金项目(No.2007-1108);珠海市政府科技计划项目(No.PA200310064)

摘　　要：天然软土剪切带性状分析一直是岩土力学界的一个研究重点。采用电镜扫描和压汞法对珠海海积软土剪切带内外以及带边缘微观结构进行定量分析,研究结果表明:珠海软土的应力-应变曲线在低围压下表现出明显应变软化特征;软土在剪切破坏后,剪切带内的微观参数变化率最大,其次是剪切带边缘,最后是剪切带外;剪切带边缘上的颗粒逐渐沿着剪切应力的方向呈定向排列,而剪切带内,由于颗粒发生破碎、折断,颗粒排列是随机的,在剪切带外,颗粒的排列受剪切破坏的影响较小;珠海海积软土的孔隙入口孔径分布为主单峰分布,其主峰峰值的位置是沿着剪切带外——带边缘——剪切带内转移;Roscoe理论和Arthur经验公式预测的剪切带倾角与实测值相比都偏小,不适宜黏性土的剪切带倾角预测计算;Mohr-Coulomb理论计算出的倾角与实测值比较一致。The investigation on shear band of natural clay has always been main topic in geomechanics. In this paper, quantitative analysis was made on microstructure of the soil inside and outside shear band in Zhuhai clay by means of scanning electron microscope （SEM） and mercury intrusion porosimetry （MIP）. The results indicate that the stress-strain curves of Zhuhai clay show obviously strain-softening behavior at low confining pressures. In comparison with microstructural parameters of the intact samples, the change of microstructural papameters is maximal inside the shear band, then on the edge of shear band, and the outside is minimal The orientation of particles on the edge of the shear band is parallel to the direction of the shear band, while the particles are generally random distributed inside the shear band, as a result of a significant breakage of the aggregates and the large particles. Distribution of particles is slightly affected in the area outside shear band by the shearing. In addition, the entrance pore size distribution of marine clay in Zhuhai demonstrates a continuous unimodal distribution, and its peak value and its corresponding pore radius decrease along the direction of outside, on the edge and inside shear band. Finally, the orientation of shear band predicted by the classical Mohr-Coulomb theory is generally consistent with the measured data, whereas the predictions by Roscoe theory and Arthur formula is significantly smaller than the experimental data.

关 键 词：海积软土 剪切带 压汞试验 微观结构 电镜扫描 

分 类 号：TU435[建筑科学—岩土工程]