摘要
饱和钙质砂地基受到地震、波浪等动荷载作用时会发生液化灾害。微生物诱导碳酸钙沉淀(MICP)是利用细菌分解尿素结晶成矿的地基处理技术。开展了MICP灌浆加固南海钙质砂地基的振动台试验,研究了MICP加固钙质砂地基的动力反应特性及抗液化性能,并分析了振动历史对钙质砂地基动力特性的影响。结果表明:MICP加固钙质砂地基在首次振动时产生的超孔压及地表沉降发展可分为平稳振荡阶段、快速增长阶段及稳定阶段3个阶段,而对于未加固模型地基则不存在稳定振荡阶段。相对于未加固地基,MICP处理后的钙质砂地基超孔压与地表沉降均有所降低,表明加固后的钙质砂地基抗液化能力得到较大提高;另一方面,处理后的土体地表加速度峰值被放大,因此,在设计地基处理方案时,需考虑MICP加固后钙质砂地基在地震作用下产生的地表加速度放大效应。MICP胶结钙质砂的抗液化强度不仅仅与颗粒胶结强度相关,还与土体密实度及颗粒排列规律有关。振动历史提高了地基土密实度,改善了钙质砂的抗液化性能,显著降低了地基的表面沉降。
Calcareous sandy foundations are susceptible to liquefaction when subjected to dynamic loading such as seismic or wave loading.The microbially induced calcite precipitation(MICP)treatment is a relatively new method to improve the liquefaction resistance of calcareous sand.In this study,several shake table tests are conducted to evaluate the seismic performance of MICP-treated calcareous sandy foundations.The influence of seismic history on dynamic performance of calcareous sand foundation is analyzed.The results indicate that the dynamic response of the soil after MICP treatment,including the excess pore water pressures and vertical settlements,can be divided into three main stages:the stable stage,rapid development stage,and gentle stage.The liquefaction resistance of MICP-treated sand is improved significantly.However,the surface accelerations for the MICP-treated models are amplified.Thus,when designing the treatment program,it is necessary to consider the tradeoff between the improved liquefaction resistance and the minimized undesirable amplified ground surface motions.The liquefaction resistance of MICP cementitious calcareous sand is related to intergranular cementation strength and relative density of soil and particle arrangement.The history of vibration improves the relative density of the foundation,and the liquefaction resistance significantly reduces the surface settlement.
作者
张鑫磊
陈育民
张喆
丁绚晨
徐盛明
刘汉龙
王志华
ZHANG Xin-lei;CHEN Yu-min;ZHANG Zhe;DING Xuan-chen;XU Sheng-ming;LIU Han-long;WANG Zhi-hua(Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering,Hohai University,Nanjing 210024,China;College of Civil and Transportation Engineering,Hohai University,Nanjing 210024,China;College of Civil Engineering,Chongqing University,Chongqing 400045,China;School of Transportation Engineering,Nanjing Tech University,Nanjing 210009,China)
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2020年第6期1023-1031,共9页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金重点项目(41831282)
国家自然科学基金项目(51679072,51879090)
中央高校基本科研业务费专项资金项目(2018B43214)
江苏省研究生科研与实践创新计划项目(SJCX19_0132)
中央高校基本科研业务费项目(2019B75414)。
关键词
微生物诱导碳酸钙沉淀
钙质砂地基
抗液化性能
动力反应特性
振动历史
振动台试验
microbially induced calcite precipitation
calcareous sandy foundation
liquefaction resistance
dynamic response
history of vibration
shake table test
