砂土内微生物诱导碳酸钙结晶的检测方法研究

为了寻找砂土中微生物诱导碳酸钙结晶(MICP)过程的无损检测方法,采用3种粒径的砂子和两种浓度的胶结溶液进行了砂土的胶结试验,检测了砂土流出液的流量、p H值、尿素浓度和Ca2+浓度等化学指标变化情况,并对碳酸钙晶体的生成数量和分布进行了分析。试验结果显示:砂土流出液的流量和Ca2+浓度能够预测MICP过程中碳酸钙晶体的生成数量,p H值和尿素浓度能够预测MICP过程中尿素的水解程度;砂土中碳酸钙晶体的生成数量与注入的Ca2+总量呈现线性增长的关系,其线性系数可以通过砂土的粒径和胶结溶液的浓度表示,胶结后砂柱的碳酸钙分布并不均匀,小粒径的砂柱上部碳酸钙含量较高,而大粒径的砂柱下部碳酸钙含量较高。

Indication method for Microbial Induced Calcite Precipitation in sand

In order to search the non-destructive detection method for Microbial Induced Calcite Precipitation (MICP) in sand, three different sizes particles and two different concentrations cementing solution were used to do the test. The flow rate, pH value, urea concentration and Ca2+ concentration were detected. The calcium carbonate amount and distribution in the cemented sand columns were also analyzed. The results showed that the flow rate and the Ca2+ concentration were indicators of the amount of calcium carbonate in sand; pH value and the urea concentration were indicators of urea hydrolysis. The relationship between the amount of calcium carbonate and the Ca2+ was linear and the linear coefficient could be expressed by the particle size of sand and the concentration of cementing solution. The distributions of calcium carbonate in the cemented sand columns were not uniform. The highest content of calcium carbonate were found in the upper part of sand column of small particles, and in the lower part of sand column of large particles.