岩石节理中MICP反应碳酸钙沉积演化规律试验研究

Experimental study on the evolution of calcium carbonate precipitation during MICP process in rock joints

微生物诱导碳酸钙沉积技术(microbially induced carbonate precipitation,MICP)在土体加固领域应用广泛,而在岩体加固领域的研究成果还不多见。为探究岩石节理MICP加固机制,利用3D打印技术制备3组具有Barton标准剖面线形貌特征的透明树脂人工模拟岩石节理试件,采用单向非循环连续灌注方法进行岩石节理MICP试验,采用数字拍照技术实时采集岩石节理中碳酸钙沉积分布图像,在此基础上分析岩石节理MICP反应过程中的碳酸钙沉积演化规律。试验结果表明:试验过程中碳酸钙首先在试件出口角点处沉积,并不断聚集扩展形成沉积区,在出口处沿宽度方向沉积区率先连通,再沿长度和宽度方向分别朝试件入口方向和中间位置扩展,最终在岩石节理试件中形成较为明显的碳酸钙沉积区和部分沉积区,在此基础上提出碳酸钙有效沉积率定量表征岩石节理试件中不同灌注时刻碳酸钙沉积区大小,得到碳酸钙有效沉积率随灌注时间变化呈现初始沉积期、稳定沉积期和加速沉积期3个阶段趋势的演化规律,并用指数函数对其进行拟合,拟合效果良好。

Microbially Induced Carbonate Precipitation(MICP)method has been widely applied for soil reinforcement,but few researches on its applications in rock mass reinforcement had been reported.In order to explore the reinforcement mechanism of MICP method for rock joints,3D printing technology was used to prepare three groups of transparent resin artificial rock joints that had the same morphological characteristics as Barton's standard profiles.Unidirectional non-cyclic grouting method was adopted for MICP tests in rock joints,and digital photography technology was used to collect real-time CaCO_(3) deposition images in rock joints,and on the basis of which the evolution of CaCO_(3) deposition during MICP process in rock joints was analyzed.From experimental results,it showed that CaCO_(3) firstly deposited and aggregated at the outlet corners,thus a CaCO_(3) deposition zone forming,and then it extended along the width direction of rock joint at the outlet.Furthermore,the CaCO_(3) deposition zone continued to extend toward the inlet and middle position of the specimen along the length and width direction,respectively.Finally,fully-deposited and partially-deposited CaCO_(3) zone were formed and CaCO_(3) effective deposition ratio was proposed to quantitatively represent the CaCO_(3) deposition zones in rock joint specimen under different grouting times.On this basis,it was obtained that the evolution law between CaCO_(3) effective deposition ratio and grouting time showed a three-stage trend which included initial deposition period,stable deposition period and accelerated deposition period.And an exponential function was proved to fit the evolution law well.