摘要
微生物诱导碳酸钙沉积是一种新型的地基处理技术,处理后的土体可以看成一种结构性土。首先,在已有三维含颗粒抗转动和抗扭转模型及三维胶结破坏准则的基础上,通过考虑颗粒碰撞接触过程中颗粒本身的塑性变形及率相关性的接触黏滞阻尼,建立考虑循环荷载作用下的三维胶结模型;然后,参考已有研究,建立了反硝化反应在加固砂土中的时效性关系。并引入CFD-DEM耦合程序,用以模拟分析不同胶结含量以及不同气泡含量下,微生物处理砂土在固结不排水循环剪切试验中的力学特性;最后,从宏微观角度分析生物胶结与生物气泡对砂土抗液化性能的影响及其作用机理。研究表明,胶结和气泡共同存在对抗液化能力的提升并没有起到"1+1=2"的效果;胶结的存在提高了非饱和砂土的抗液化能力,明显抑制孔压比和轴向应变的发展,力学配位数得到了提升;而气泡的存在却降低了胶结砂土的抗液化能力,使得胶结砂土达到初始液化的振次减少,轴向应变向受拉方向大幅增长,力学配位数下降明显。
The microbially induced calcite precipitation is a promising technology to improve ground, and the treated soil can be regarded as the structural one. In this study, firstly, based on the three-dimensional(3 D) contact model for granulates incorporating rolling and twisting resistances and 3 D bonds failure criteria, and considering both the slight plastic deformation of particles during collisions and the rate-dependency, a cyclic bonded contact model is established. A time-dependent relationship is then proposed to describe the denitrification reaction in reinforced sand. Next, the mechanical responses of microbially treated sands at different cementation and bubble contents are investigated by the coupled CFD-DEM in undrained-consolidated cyclic triaxial tests. The effects of biological bond and biological bubbles on the liquefaction resistance of sands are analyzed in link with the mechanism from macroscopic and microscopic scales. The results show that the coexistence of cementation and bubble does not increase the liquefaction resistance as expected in the form of "1+1=2". The presence of cementation enhances the liquefaction resistance of unsaturated sands evidenced by the decrease of excess pore water pressure ratio and axial strain, and the increase of coordination number. However, the presence of bubbles reduces the liquefaction resistance of cemented sands, where the number of cycles to the initial liquefaction decreases, the axial strain increases significantly in the tensile direction, and the coordination number decreases significantly.
作者
蒋明镜
孙若晗
李涛
杨涛
谭亚飞鸥
JIANG Ming-jing;SUN Ruo-han;LI Tao;YANG Tao;TAN Ya-fei-ou(Department of Civil Engineering,School of Civil Engineering,Tianjin University,Tianjin 300072,China;State Key Laboratory of Hydraulic Engineering Simulation and Safety,Tianjin University,Tianjin 300072,China;State Key Laboratory of Disaster Reduction in Civil Engineering,Tongji University,Shanghai 200092,China;Department of Geotechnical Engineering,Tongji University,Shanghai 200092,China;School of Environment and Architecture,University of Shanghai for Science and Technology,Shanghai 200093,China)
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2020年第1期20-28,共9页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金重大项目（51890911）
国家自然科学基金重点项目（51639008）
