浓缩海水作为钙源在微生物诱导碳酸钙加固砂土中的应用

Application of concentrated seawater as calcium source solution in sand reinforcement using MICP

为了将海水作为原料利用于微生物诱导碳酸钙(MICP)加固岛礁地基,进行了海水浓缩试验以及将浓缩海水作为钙源溶液的MICP砂土加固试验,研究细菌固定方式、细菌注入批次、胶结液中尿素浓度以及胶结液注入流速对加固效果的影响。研究表明,在不析出钙离子的条件下,将海水进行浓缩的最高倍数为3倍,此时钙离子含量约为0.033mol/L;尿素添加量宜为浓缩海水中钙离子含量的3倍,可有效利用胶结液中钙离子产生沉淀;使用2 mL/min的胶结液注入流速对5 cm砂柱进行加固可以得到最佳加固效果;加固后砂柱无侧限抗压强度达653 kPa,耗时4.5 d;增加细菌注入批次无法对砂柱加固效果进行有效改善。

To use seawater as the raw material in the reef foundation reinforcement based on microbial induced calcite precipitation(MICP),seawater concentration test and MICP sand reinforcement test with concentrated seawater as calcium source solution were carried out.In this work,the influence of bacterial fixation mode,bacterial injection batch,the urea concentration in cement solution and the injection velocity of cement solution on the reinforcement effect were studied.The research results showed that the maximum concentration of seawater is three times the original concentration under the condition of no precipitation of calcium ion,and the content of calcium ion is about 0.033 mol/L.The amount of urea added should be 3 times that of the content of calcium ion in concentrated seawater,so that the calcium ion in cementation liquid can be effectively used to produce precipitation.The best reinforcement effect can be obtained by using the cement injection velocity of 2 mL/min to reinforce 5 cm sand column samples.After reinforcement,the unconfined compressive strength of the sand column sample can reach 653 kPa,which takes 4.5 days.Increasing the batch of bacterial injection cannot effectively improve the reinforcement effect of the sand column.