碳酸酐酶增强微生物矿化固土效果的试验研究  

Experimental study of enhancing the effects of microbial-induced calcite precipitation treated sand using carbonic anhydrase

作　　者：刘鹏[1] 曹源兴 程钰 白云波 LIU Peng;CAO Yuan-xing;CHENG Yu;BAI Yun-bo(School of Civil Engineering,Nanjing Forestry University,Nanjing,Jiangsu 210037,China;School of Transportation,Shandong University of Science and Technology,Qingdao,Shandong 266590,China;Shanghai Civil Engineering Group Co.Ltd.of CREC,Shanghai 201906,China)

机构地区：[1]南京林业大学土木工程学院,江苏南京210037 [2]山东科技大学交通学院,山东青岛266590 [3]中铁上海工程局集团有限公司,上海201906

出　　处：《岩土力学》2024年第9期2554-2564,共11页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.51809139)。

摘　　要：为了提升微生物固化砂土的效果,从自然界微生物主动参与碳循环、激发碳化现象中得到启发,利用碳酸酐酶(carbonic anhydrase,简称CA)能显著提高CO_(2)水合反应速率(提高108倍),促进脲酶(urease,简称UA)分解尿素生成的CO_(2)迅速水合形成大量CO_(3)^(2-)的特性,设计并进行了碳酸酐酶增强微生物矿化固化砂土试验,综合宏观物理力学试验和微细观检测,系统分析了碳酸酐酶对微生物固化砂土的增强效果及增强机制。结果表明:(1)碳酸酐酶能够显著提高砂土微生物加固过程中的胶结物产量,碳酸酐酶菌掺量在4%左右达到最佳,与常规微生物诱导碳酸盐沉淀(microbial-induced carbonate precipitation,简称MICP)相比,胶结物生成量提高了105.3%。(2)碳酸酐酶的掺入提高了固化体的抗压强度和抵抗变形能力,在0.25%~4.00%掺量范围内,固化土样的无侧限抗压强度随碳酸酐酶菌掺量的增加而增大。当掺量为4.00%时固化土样的强度达到1.915 MPa,为常规MICP固化试样强度的8.54倍。(3)碳酸酐酶没有改变MICP过程的产物,仍是方解石。但在添加了CA后,方解石的晶粒尺寸更大,六面体形状更规范,力学性能也更好。(4)在MICP过程中,脲酶和碳酸酐酶相互协同沉淀碳酸钙固化砂土。碳酸酐酶可以显著加速脲酶分解尿素生成的CO_(2)水合并形成HCO_(3-)和CO_(3)^(2-)的速率,为矿化物沉降提供更有利的条件。This study aimed to enhance the efficiency of microbial-induced carbonate precipitation(MICP)for reinforcing sandy soil by inspiring natural processes involving microbial-induced carbon cycling and carbonation.The experiment focused on enhancing MICP curing of sandy soil using carbonic anhydrase(CA),which significantly increases the reaction rate of CO_(2)hydration(108 times faster)and facilitates the rapid hydration of CO_(2)(produced by urease(UA)decomposition of urea)to form a substantial amount of carbonate.The effect of carbonic anhydrase on MICP-reinforced sandy soil and its underlying mechanism were systematically examined through a combination of macroscopic physical and mechanical tests and microfabrication tests.The results showed that:(1)CA significantly increases the production of cement during the microbial consolidation of sandy soils,and the optimum dose of carbonic anhydrase producing bacteria is reached at about 4%,which increases the production of cement by 105.3%,compared with conventional MICP.(2)The incorporation of CA improves the compressive strength and resistance of the cured body.In the range 0.25−4.00%,the unconfined compressive strength of the solidified soil sample increases with the increase of the CA bacteria content.The strength of the cured soil sample reaches 1.915 MPa when the content is 4%,which is 8.54 times the strength of the conventional MICP cured sample.(3)CA does not change the product of the MICP process,it is still calcite,but after adding CA,the grain size of the calcite is larger,the shape of the hexahedron is more standardised,and the mechanical properties are improved.(4)In the process of MICP,urease and CA co-precipitate calcium carbonate-cured sandy soil.CA can significantly accelerate the rate of urea-generated CO_(2)hydrate and form HCO_(3-)and CO_(3)^(2-),providing more favourable conditions for mineralisation.

关 键 词：碳酸酐酶 微生物诱导碳酸盐沉淀(MICP) 矿化 脲酶 水合反应 力学性能 

分 类 号：TU411[建筑科学—岩土工程]