Characteristics of floor failure under the double action of mining and hidden faults

Aiming at the problem of frequent occurrence of floor water damage under the condition that the floor has hidden faults, two methods of comprehensive numerical calculation and on-site measurement are used to explore the characteristics of floor rock mass mining failure. The simulation results show that the range of floor plastic zone expands with the increase of the working face advancement distance. The maximum failure depth of the intact floor rock mass far away from the bottom floor hidden fault is about 18 m, and the maximum failure depth of the rock body near the bottom floor hidden fault is about 28 m. The activation of the hidden fault is a positive factor to promote the increase of the floor bottom depth; due to the influence of the presence of hidden faults, the mining failure range of the floor rock mass exhibits a positive “eight” type of failure form with the vertical axis at the top of the hidden fault as the symmetry axis; borehole peep observations show that the fracture penetration type appears in the affected area of mining failure. The characteristic of the “ring-shaped” failure circle is that the maximum mining failure depth of the floor is about 29 m. The results show that: under the influence of concealed faults and mining stress, the failure depth of the bottom plate increases significantly, and the extension path develops obliquely downwards along the top of the concealed faults. The error between the numerical simulation and the measured results is about 3.4%.