木质素磺酸钙增强花岗岩残积土微生物固化效果研究

Effect of calcium lignosulfonate on mechanical properties of fully weathered granite solidified by microorganism

为提升微生物固化花岗岩残积土的效果,综合考虑木质素磺酸钙的特点和MICP(Microbial-induced calcite precipitation)作用过程的环境条件,设计进行木质素磺酸钙增强MICP固化花岗岩残积土试验,综合宏观物理力学试验和微细观检测,系统分析木质素磺酸钙对微生物固化花岗岩残积土的增强效果及增强机制。结果表明:①木质素磺酸钙能够显著提高花岗岩残积土微生物加固过程中的胶结物产量,木钙掺量在4.00%左右达到最佳,与常规MICP相比,胶结物生成量提高了48.86%;②木质素磺酸钙的掺入,显著提高了固化体的抗压强度和抵抗变形能力,2.00%~8.00%掺量下固化体的抗压强度提升了4.75%~41.20%,破坏时应变增加16.24%~38.55%;③掺入木质素磺酸钙后,固化体的孔隙大小及孔隙率均有不同程度降低,孔隙率降低了12.97%~37.38%,固化体的整体密实性进一步增强;④木质素磺酸钙的掺入,改善了残积土的孔隙结构,为后续微生物加固提供更好的环境条件;⑤在微生物固化花岗岩残积土过程中掺入木质素磺酸钙后,改善了微生物生长的酸碱环境,丰富了MICP作用过程中的钙源,提升了固菌率,促进了MICP反应,同时改善了碳酸钙沉淀颗粒的大小、性状及排列形式,使得胶结物产量进一步提升,从而提升固化体的整体固化效果。

To further investigate the effect of MICP(microbial-induced calcite precipitation)granite residual soil,taking into account the overall nature of calcium lignosulfonate and the ambient conditions of the MICP process,calcium lignosulfonate-reinforced MICP solidified granite residual soil was designed and tested.A synthetic macroscopic physical mechanics test and a microscopic examination was conducted,and the augmentation effect and mechanism of calcium lignosulfonate on residual solidified granite microbial soil was systematically analyzed.The research results demonstrate that:(1)Calcium lignosulfonate can signally enhance the yield of cement in the process of microbial strengthening of granite residual soil.with the best calcium content around 4.00%.Agglutinate production was increased by 48.86%compared to conventional MICP.(2)Incorporation of calcium lignosulfonate significantly improved the compressive strength and deformation resistance of solidified body,the compressive strength of solidified body was increased by 6.98%~41.20%with a dosage of 2.00%~8.00%,and the strain was increased by 16.24%~38.55%at the time of failure.(3)With the addition of calcium lignosulfonate,the pore size and porosity of the solidified body decreased with a decrease of porosity 12.97%~37.38%,and the overall compactness of the solidified body further increased.(4)There was some cementation effect of calcium lignosulfonate on the residual granite soil,improving the pore structure of residual soil,and providing better environmental conditions for subsequent microbial reinforcement.(5)Due to the addition of calcium lignosulfonate,the acid-base environment for microbial growth was improved,the calcium source in the MICP process was enriched,the rate of solidification was increased,and the MICP reaction was promoted.At the same time,the size,properties,and arrangement of the calcium carbonate precipitation particles were improved,the performance of the cement was further increased,and the overall solidifying effect of the solidified body was enhanced.