In the underground engineering construction, grouting is a common means of the disaster management projects. Grouting can improve the mechanical parameters of surrounding rock and the stress state of surrounding rock. Grouting is benefit for the surrounding rock stability and roadway safety in long term. But the slurry cannot have the carrying capacity immediately; the pump pressure will be passed on the surrounding rock. The pump pressure is an additional load, and it is result in a large deformation of the soft rock roadway. Using the composite beam model, the critical value of the grouting pressure leading to floor heave is obtained. By numerical simulation method, the value of the grouting pressure carried by the surrounding rock is calculated. Through theoretical analysis and numerical simulation methods, the limit grouting pressure is determined in Longgu coal mine. By the observation of surrounding rock deformation in Longgu coal mine, the law of the rock deformation under grouting pressure is analyzed. This research is a good reference for similar projects.
Grouting is one of the common methods to govern the underground engineering disaster, and it has significant effect on dealing with landslides, gushing water, soft rock reinforcement. Because the solidification of the cement slurry needs longer time (6-8h), the slurry is liquid in a period of time. The pump pressure is passed on the surrounding rock by the slurry, and it is an additional load on the surrounding rock. At the same time, its own weight will be carried by the surrounding rock. These two factors lead to the increase of surrounding rock deformation, serious or even destroy. With regard to the mechanism of the grouting pressure on the surrounding rock and floor heave in soft rock roadway, many scholars have done extensive research [1-5]. But the existing research usually takes the grouting method as a means of floor heave governance, the research on the negative aspects of the grouting pressure is less. The analysis on the floor heave caused by grouting pressure is little. This paper analyzes the floor heave caused by grouting pressure in Longgu coal mine, calculates the distribution law of the grouting pressure with numerical simulation method, studies the mechanism of the floor heave and the monitoring datas of the surrounding rock deformation. The result of this research is useful to the similar projects.
Auxiliary-2 haulage roadway gets through several rock formations, and the buried depth of auxiliary-2 haulage roadway is 780-800m. Water inflow mainly takes place in formations of limestone, mudstone, argillaceous fine sandstone, siltstone, fine sandstone and so on. The limestone formation is cut off by two main faults, FL8-1 and FL8-2, which leads to the large water inflow. From the entrance of NO.2 sump, there is about 300m water inrush section, which contains roof and floor. The total water flow rate, water pressure and water temperature of the above section are 760m³/h, 3MPa and 49ºC respectively.(Fig 1)- Fig. 1. Water inrush (roof and floor) in Longgu coal mine.