基于颗粒尺寸与级配的微生物固化钙质砂最大动剪切模量试验研究  

Experimental study on maximum dynamic shear modulus of MICP-treated calcareous sand based on particle size and gradation

作　　者：单毅 平阳泽 袁杰[1,2] 崔杰 童华炜[1,2] 李亚东[1,2] SHAN Yi;PING Yangze;YUAN Jie;CUI Jie;TONG Huawei;LI Yadong(School of Civil Engineering,Guangzhou University,Guangzhou,Guangdong 510006,China;Guangdong Engineering Research Center for Underground Infrastructural Protection in Coastal Clay Area,GuangzhouUniversity,Guangzhou,Guangdong 510006,China)

机构地区：[1]广州大学土木工程学院,广东广州510006 [2]广州大学广东省滨海软土地区地下结构安全防护工程技术研究中心,广东广州510006

出　　处：《岩石力学与工程学报》2024年第10期2455-2465,共11页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家重点研发计划项目(2022YFC3003601);国家自然科学基金资助项目(52008121);广东省自然科学基金资助项目(2023A1515030051)。

摘　　要：微生物诱导碳酸钙沉淀(MICP)是一种用于改善砂土动力特性的降碳减污型加固技术。利用MICP加固技术对南海海域钙质砂样进行加固处理,并开展一系列共振柱试验与扫描电子显微镜试验,系统地讨论颗粒尺寸d_(50)、不均匀系数C_(u)及曲率系数C_(c)对MICP固化砂最大动剪切模量G_(max)的影响。试验结果表明:钙质砂的G_(max)随着d_(50)增大而增大,随着C_(u)增大而减小,随着C_(c)增大而先减小后增大;与此同时,MICP固化砂的G_(max)与C_(u)和C_(c)的对应关系跟钙质砂保持相同,但G_(max)则随着d_(50)增大而先增大后减小;此外,MICP固化效果与碳酸钙含量相关,而碳酸钙含量的差异归因于颗粒尺寸大小与颗粒级配均匀性的差异,其主要通过孔隙数量和体积的不同来影响细菌的滞留量。针对是否考虑碳酸钙含量修正的初始孔隙比,提出考虑颗粒尺寸与级配特征的G_(max)预测模型,并采用大量文献数据验证模型的有效性与适用性。该试验研究可为采用MICP技术改善钙质砂动力特性的实际工程运用提供理论依据。The microbially induced calcite precipitation(MICP) is a reinforcement technique aiming at reducing carbon emissions and pollution,and it can effectively enhance the dynamic properties of sandy soils.The MICP is applied to strengthen calcareous sand samples in the South China Sea region.A series of resonant column tests and scanning electron microscope tests are conducted to thoroughly investigate the impact of particle size(d_(50)),uniformity coefficient(C_u),and curvature coefficient(C_c) on the maximum dynamic shear modulus(G_(max)) of MICP-treated sandy soils.The experiment results indicate that the G_(max) of untreated sand increases with increasing d_(50),decreases with increasing C_u,and initially decreases and then increases with increasing C_c.Meanwhile,the G_(max )of the MICP-treated sand maintains the same relationship with C_(u) and C_(c) of the untreated sand,but it increases initially and then decreases with increasing d_(50).Furthermore,the MICP cementing effect correlates with the calcium carbonate content,with differences in calcium carbonate content attributed to variations in particle size and uniformity of particle gradation,which mainly influence bacterial retention through differences in pore number and volume.Separate G_(max) prediction models considering particle size and gradation characteristics are proposed,with a large amount of literature data used to verify the validity and applicability of the proposed models,depending on whether the initial pore ratio corrected for calcium carbonate content is taken into account.The experimental study provides a theoretical basis for the practical engineering application of MICP to improve the dynamic properties in calcareous sands.

关 键 词：岩土工程 微生物固化 钙质砂 最大动剪切模量 颗粒尺寸 颗粒级配 预测模型 

分 类 号：TU43[建筑科学—岩土工程]