低温条件下微生物诱导碳酸钙沉积加固土体的试验研究

Experimental research on influence of low temperature on MICP-treated soil

微生物诱导碳酸钙沉积(MICP)加固土体是近年来受到学术界重视的问题,但是对实际土壤温度下MICP加固土体的可行性及效果研究未见报道。利用尿素水解菌ATCC 11859,进行了微生物诱导碳酸钙沉积的试管试验及一维砂柱试验,研究了不同温度下微生物诱导生成碳酸钙的特性及对土体的加固效果。试管试验表明温度越高生成的碳酸钙越多,在不同温度下微生物诱导生成的碳酸钙晶型无显著差异,但是温度对碳酸钙的生成速率有明显影响。一维加固试验表明MICP在一般土壤温度条件下都能够有效地加固土体,但低温下MICP加固的试样强度较低,渗透系数较高。

The microbially induced carbonate precipitation（MICP） has become an active issue in the field of geotechnical engineering. However, the feasibility and reinforcement effects of this technology at low temperature are not available in previous literatures. A series of tube tests and one-dimesion sand column trials using ureolytic bacteria ATCC11859 are conducted to investigate the influence of ambient temperature on MICP behavior and stabiliszaion effectiveness. The tube test results show that the final amount of calcium carbonate is much more in high temperature than lower temperature, and the temperature has a notable influence on the formation rate of precipitations instead of the morphology of Ca CO3 in aqueous medium. The experiments on coarse sand treated with surface percolation demonstrate the validity of bio-grout at common soil temperature, whereas the MICP-treated sand column has a relatively lower UCS as well as higher permeability coefficient at low temperature.