胶结液浓度对微生物固化花岗岩残积土强度特性的影响规律

在分析花岗岩残积土物理特性的基础上，选用巴氏芽孢杆菌菌液和不同浓度的氯化钙与尿素的混合胶结液，利用设计的室内试验装置对花岗岩残积土开展不同灌注次数的微生物固化试验，并对不同工况的固化试样进行无侧限抗压强度（UCS）试验、碳酸钙生成率测试和崩解试验，同时开展X射线衍射（XRD）和扫描电子显微镜（SEM）等微观结构分析，以此探讨胶结液浓度和灌注次数对固化后花岗岩残积土强度特性的影响规律. 结果表明：试验参数范围内，灌注次数相同时，胶结液浓度为1.0 mol/L时，试样的固化效果最好；胶结液浓度相同时，灌注次数越多，试样的固化效果越好；固化试样的崩解性大大降低，崩解系数均小于30%；微生物固化生成的方解石晶体呈现明显的簇状，填充、胶结在土颗粒之间，与砂土的微生物固化特性具有一定差异性，但两者的固化过程与机理具有相似性.

Effect of Cement Concentration on the Strength Characteristics of Biocemented Granite Residual Soil

Based on the analysis of the physical properties of granite residual soil， microbial induced carbonate precipitation experiments are conducted on granite residual soil with different perfusion times in the designed laboratory test device， using a mixture cement of bacillus pasteurii with calcium chloride and urea colloidal solution under different concentration. Experiments are conducted on cemented specimens of different treatment conditions for the Unconfined Compression Strength （UCS） experiment， calcium carbonate precipitation experiment and disintegration experiment. In this paper， X-Ray Diffraction （XRD） and Scanning Electron Microscopy （SEM） are also used to analyze the microstructure besides. Based on the above experiments， the effect of cement concentration and perfusion times on the strength characteristics of cemented granite residual soil is investigated. The results show that the cementing effect of the specimens is best when the concentration of the cementing solution is 1. 0 mol/L within the range of the experiment parameters and the perfusion times are the same. When the concentration of the cementing solution is the same， the more perfusion times， the better the cementing effect of the specimens. The disintegration of the cemented specimens is greatly reduced， and the disintegration coefficients are less than 30%. In addition， the calcite crystals produced by biocement appear as distinct clusters， which fill and cement between the soil agglomerates. This is distinct from the microbial cementing properties of sandy soils， but the cemented process and mechanism of both are similar.