In order to study the mechanism of debris flow in the underground development project of weak cemented aquifer, the weak cemented sandstone of a mine in Xinjiang was taken as the research object, and its cementation characteristics and water characteristics were analyzed. The mathematical models of porosity, expansion rate and permeability were used to obtain the permeability of weak cemented aquifer under different expansion rates. On this basis, the fluid-solid coupling model was used to analyze the changes of surrounding plastic zone and seepage field in the process of water expansion of surrounding rock of roadway loose circle under different buried depth conditions.The research shows that the water expansion of surrounding rock will increase the permeability of aquifer and improve its permeability. When the expansion rate of surrounding rock increases to 30%, the unit water inflow after roadway excavation will increase by 1.5 to 2.0 times, and with the increase of development depth, the unit water inflow will increase greatly, which will provide sufficient water source for the occurrence of underground debris flow. The strength of weak cemented siltstone is low, and it is easy to form a plastic failure zone on the tunnel face of the development project. With the increase of the development depth, the plastic failure of the tunnel face is greater, and it is easy to collapse and decompose into a source under the condition of groundwater erosion and scour. The stability of surrounding rock in the underground fracture development area is poor, the groundwater seepage channel is smooth and the supply is sufficient. It is easy to expand, collapse and decompose under the action of groundwater, and it is carried by groundwater to form debris flow, which is the key area of underground debris flow. The research results are helpful to further reveal the formation mechanism of debris flow in the underground development project of weak cemented aquifer.

Weak cemented aquifer  /  Underground debris flow  /  Expansion rate  /  Permeability  /  Unit water inflow