Analysis of rock grouting with variable injection pressure

Abstract: Rock grouting is an effective technique frequently used in rock engineering to reduce  groundwater ingress and increase the stability of surrounding rock mass. The real time grouting control (RTGC) is one of widely used  analytical models to predict the grouting process. In previous research, this method was discussed under constant pressure condition. However, in practice, the injection is not always constant. The effect of variable injection pressure was not fully discussed. In this study,  a 2D radial single-phase flow model is applied to describe the rock grouting process. The model  is solved using numerical integration to incorporate variable injection pressure. The sensitivity of the model is reviewed afterward. In this paper, the dynamic grouting technique is analyzed using the new model. Field data from three rock engineering projects are compared with the model prediction to assess the performance of the model. The results from  the traditional  RTGC  method  are  compared with the model prediction.  The results show that  modeling prediction using variable injection  pressure condition significantly differs from that using constant injection pressure.  Moreover, time-variable model which is an extended version of the traditional RTGC theory shows a slightly better prediction when compared with recorded data and RTGC result. It also can be concluded that dynamic grouting could improve grouting performance from an analytical perspective. In the end, this research would result in an effective tool for further study in this field.