大豆脲酶诱导碳酸钙固化黄土的强度试验研究

Experimental study on the strength of loess solidified by soybean urease-induced calcium carbonate precipitation

大豆脲酶诱导碳酸钙沉积(SICP)是一种植物酶微生物矿化技术,为了探究其在黄土工程中的应用前景,开展0~4.5 mol/L胶结液浓度下固化黄土的不固结不排水三轴试验,分析固化前、后黄土强度及应力-应变关系,通过SEM和XRD测试固化前、后黄土微观结构变化和矿物组成。结果表明,随胶结液浓度增大,黄土强度先增大后减小,胶结液浓度为2.5 mol/L时,强度最大;经SICP固化后,黄土强度显著提升,最大为2066.63 kPa,较未固化土至少增大1.31倍。SEM测试表明,SICP固化生成的碳酸钙晶体可以填充土粒孔隙,胶结部分土颗粒,进而提高土体强度;XRD测试表明,固化前后黄土的主要矿物成分不变,但固化后碳酸钙晶体的衍射峰数量和高度明显增加。成果可为应用SICP技术固化黄土提供新思路。

Soybean urease-induced carbonate precipitation(SICP)is a technology for microbial mineralization of plant enzymes.The unconsolidated undrained triaxial test was conducted on the solidified loess at a cementation solution concentration of 0-4.5 mol/L to explore the prospect of its application in loess engineering.The strength and stress-strain relationship of loess before and after solidification were analyzed,and the microstructure changes and mineral composition of loess before and after solidification were also tested via SEM and XRD.The results show that the strength of loess first increases and then decreases with the rise in the cementation solution concentration,revealing the maximum value when the concentration of cementation solution is 2.5 mol/L.The strength of loess is substantially increased by the solidification of SICP,revealing a maximum value of 2066.63 kPa,which is at least 1.31 times larger than that of unconsolidated soil.The SEM test results show that the calcium carbonate crystals generated by SICP can fill the pores of soil and cement some soil particles,thus improving the strength of the soil.The XRD test results reveal that the main mineral composition of loess remains unchanged before and after solidification,while the number and height of diffraction peaks of calcium carbonate crystals drastically increase after solidification.Overall,these results can provide new ideas for the application of SICP technology for loess solidification.