MICP胶结钙质砂动力特性试验研究  

Dynamic behaviors of MICP-treated calcareous sand in cyclic tests

作　　者：刘汉龙[1,2,3] 肖鹏[1,2] 肖杨[1,2] 王建平[4] 陈育民[3] 楚剑[1] 

机构地区：[1]重庆大学土木工程学院,重庆400045 [2]重庆大学山地城镇建设与新技术教育部重点试验室,重庆400045 [3]河海大学土木与交通学院,江苏南京210098 [4]海军工程设计研究局,北京100070

出　　处：《岩土工程学报》2018年第1期38-45,共8页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(51578096);高等学校学科创新引智计划项目(B13024)

摘　　要：以南海某岛的钙质砂为材料进行微生物（MICP）胶结加固,通过动三轴试验和SEM微观结构试验,研究了MICP胶结钙质砂在不同胶结程度和不同动应力水平下的动强度、动变形、动孔压、有效应力路径的发展规律和MICP胶结的微观机理。结果表明：通过MICP胶结的钙质砂动剪应力比和抵抗变形的能力得到明显提高,这表明MICP胶结作用能显著改善钙质砂抗液化能力。MICP胶结钙质砂的孔压发展可以分为4个阶段：初始阶段—稳定发展阶段—快速发展阶段—完全液化阶段,当孔压发展到快速阶段末期,孔压曲线出现凹槽,试样开始失稳,最后发生破坏。整个振动循环过程中土体的变形和强度变化与有效应力路径和孔压的发展密切相关,当试样发生破坏时,有效应力路径表现出循环活动性。MICP胶结作用生成了方解石结晶包裹在砂土颗粒表面或填充于砂颗粒之间,这改变了土体的性质,使得土体的黏聚力和内摩擦角均有所提高。The calcareous sands from an island of the South China Sea are cemented by the microbially induced calcite precipitation （MICP） method. A series of cyclic tests and SEM tests are carried out to investigate the evolutions of the dynamic strength, dynamic deformation, dynamic pore pressure and effective stress path under different degrees of bio-cement as well as the micromechanism of the MICP-treated calcareous sands. The results show that the cyclic stress ratio and resistance to deformation of the calcareous sands are obviously improved due to the MICP method, implying that the MICP method can significantly improve the dynamic properties of calcareous sands. The evolution of the dynamic pore pressure can be divided into four stages： initial phase, stable development phase, rapid development phase and complete liquid phase. The sample begins to collapse when the pore pressure is developed at the later period of the rapid development phase, and the groove appears in the pore pressure curve. In the whole phase, the soil deformation and the change in soil strength are closely related to the development trend of the effective stress path and dynamic pore pressure, and then, the effective stress path exhibits cyclic mobility. The particles of the MICP-improved calcareous sands are wrapped or filled by the calcite precipitation, leading to the changed properties of calcareous sands, which increases the cohesion and internal friction angle of soils.

关 键 词：MICP胶结钙质砂 动强度 动应变 动孔隙水压力 有效应力路径 SEM 

分 类 号：TU435[建筑科学—岩土工程]