黄河流域内蒙古段砒砂岩风化土微生物矿化改良的试验研究  

Experimental study on improvement of weathered Pisha sandstone soil in Inner Mongolia section of the Yellow River Basin based on microbially induced carbonate precipitation technology

作　　者：王燕星[1,2] 李驰 葛晓东[3] 高利平 WANG Yan-xing;LI Chi;GE Xiao-dong;GAO Li-ping(College of Civil Engineering,Inner Mongolia University of Technology,Hohhot,Inner Mongolia 010051,China;College of Science,Inner Mongolia University of Technology,Hohhot,Inner Mongolia 010051,China;Inner Mongolia No.3 Geological and Mineral Exploration and Development Co.,Ltd,Hohhot,Inner Mongolia 010011,China)

机构地区：[1]内蒙古工业大学土木工程学院,内蒙古呼和浩特010051 [2]内蒙古工业大学理学院,内蒙古呼和浩特010051 [3]内蒙古第三地质矿产勘查开发有限责任公司,内蒙古呼和浩特010011

出　　处：《岩土力学》2022年第3期708-718,共11页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.51968057);内蒙古自治区科技重大专项(No.2020ZD0021);内蒙古自治区科技计划关键技术攻关项目(No.2021GG0344)。

摘　　要：砒砂岩,一种在黄河中上游广泛分布的特殊岩石,是由砂页岩和泥质砂岩组成的岩石互层,由于成岩程度低、沙粒间胶结程度差、结构强度低,且含有大量黏土矿物,其抗侵蚀能力弱,遇风成沙、遇水成泥,是“泥沙入黄”的重要来源。基于微生物诱导碳酸钙沉积(microbially induced carbonate precipitation,MICP)技术对砒砂岩风化土进行改良加固,以矿化后试样获得良好的强度为目标,结合物性及孔隙结构分析,对含有大量细粒土的砒砂岩风化土进行微生物矿化改良试验的最优方案设计。试验方案中设置12种工况,通过菌液浓度、菌液与胶结液用量比、钙尿摩尔比3个控制要素,对经微生物诱导沉积的碳酸钙晶体的晶型、形貌和尺寸进行人为调控。试验结果表明,当微生物矿化试验中尿素消耗量为0.4 mol时,采用菌液浓度OD_(600)值为1.2、菌液与胶结液用量比为1:20、钙尿摩尔比为1:1的试验方案,经微生物诱导的碳酸钙晶体以20~30μm的“方解石-球霰石团聚体”的晶型被沉积,并填充于砒砂岩风化土的孔隙中,使得砒砂岩风化土密实度提高,矿化后试样的孔隙度减小了62.4%,抗蚀能力得到增强。改良后的试样表现出良好的强度特性,无侧限抗压强度达到了1.0 MPa。由于微生物诱导的碳酸钙晶体的填充和胶结作用,浸水饱和后试样的强度尚保留43.6%,很好地解决了砒砂岩遇水溃散的问题。研究结果拓展了MICP技术在含有大量细粒土的混合土加固中的应用,为改良后砒砂岩风化土的工程推广应用提供了理论基础和试验依据。Pisha sandstone is a kind of special rock widely distributed in the middle and upper reaches of the Yellow River, which is composed of sand shale and argillaceous sandstone. Due to the low diagenetic degree, the poor cementation between sand grains, the low structural strength, and containing a large number of clay minerals, its anti-weathering ability is weak. Pisha sandstone becomes sand when encountering wind and becomes mud when encountering water, which is an important source of "sediment delivery into the Yellow River". Based on microbially induced carbonate precipitation(MICP) technology, the weathered Pisha sandstone soil was improved and reinforced. Aiming to obtain good strength of improved soil samples and combine with the analysis of physical properties and pore structure, the optimal scheme design of improvement for the soils containing many fine-grained soils was carried out. Under 12 working conditions, the artificial control with crystal forms, crystal morphology, and crystal size were carried out through three experimental control factors: the concentration of the bacterial solution, the dosage ratio of bacterial solution to calcium source solution, and the molar ratio of calcium to urea. The results show that when the urea consumption was 0.4 mol, using the test scheme that the bacterial solution concentration OD_(600) was 1.2, the ratio of bacterial solution to calcium source solution was 1:20,and the ratio of calcium to urea was 1:1, it is found that the calcium carbonate crystal induced by microorganisms was deposited in the form of "20-30 μm calcite-vaterite aggregates". These aggregates were filled in the pores of the weathered Pisha sandstone soil to increase the soil compactness, and therefore the sample porosity was reduced by 62.4%, enhancing the corrosion resistance. The improved soil also showed good strength characteristics with 1 MPa of unconfined compressive strength. Due to the filling and cementation of this calcium carbonate crystal, the strength remained 43.6% after being satu

关 键 词：砒砂岩 微生物诱导碳酸钙沉积(MICP)技术 晶体调控 孔隙特征 

分 类 号：TU470[建筑科学—结构工程]