Flexural floor heave mechanism and floor corner piles control technology in soft rock roadway

In order to solve the problem of flexural floor heave support under the condition of weak floor with high stress, the supporting form of concrete filled steel tube floor corner pile is put forward. The failure characteristics of the surrounding rock of the flexural floor are studied on the research background of the 18-floor south track roadway of the fourth level in Xing'an Mine. Based on the deflection theory of slab and the virtual work principle, the instability criterion of flexure-type floor under the condition of floor corner pile support is given, and the support mechanism of foundation pile is studied. The results show that the high stress and insufficient strength of surrounding rock are the main reasons for the instability of roadway floor and weakening the stress of floor rock and strengthening the floor rock are the key to control the flexural floor heave. The sectional geometry parameters and pile spacing of piles are the key design parameters to determine the ultimate resistance. The pile length should include the embedding depth of 0.4 R ~ 0.6 R(R is the plastic zone radius), and the pile should be laid through the equivalent circle radius of the roadway section or in a vertical direction. Based on the above research, a field test was carried out on floor corner pile. The field monitoring results show that the pile foundation stress of the floor has a good barrier effect on the compressive stress of the surrounding rock of the roadway floor, and the deformation of the floor and the two sides can be well controlled, and the stability of roadway can be significantly improved. This control technology can provide a reference for roadway floor heave support under similar conditions.