Abstract:
Due to the underground coal mining,the water in the mining-destroyed aquifer will unevenly flow to the working face through the mining failure rock mass. There will be the main channel of water flow in the wa-ter-conduc- ted fracture zone. In this circumstance,it is necessary to reveal the distribution law of water-conducted fracture main channel and its flow characteristics,which is helpful for water inflow prediction,roof flood control,and water preserve mining. Based on the type partition of water-conducted fracture and the mechanical analysis of seepage flow or pipe flow model,the distribution model of water-conducted fracture main channel was studied. The results show that it is easy to occur post-peak compression shear fracture in the rock mass area out of the mining boundary due to the pre- support pressure. The flow pattern is non-Darcy flow while water flows through the fracture. Besides,another fracture type occurs during the strata breaking movement which is named as shear fracture. Due to the larger value of Reynolds number,the flow pattern belongs to pipe flow. Affected by the broken position against the mining area,the shear frac- ture can be divided into three types,which are upper stretch-draw fracture,lower stretch-draw fracture,and close frac- ture. According to the Forcheimer formula and Bernoulli equation,the difference of the four kinds of two types fracture was revealed. It can be concluded that the value of the characteristic parameters of upper stretch-draw fracture is the largest in terms of open degree of fracture inlet,water flowrate,and flow velocity in the fracture exit. In addition,the water flow from the nearby compression shear fracture and lower stretch-draw fracture can supply to the upper stretch- draw fracture due to its low hydraulic pressure in the fracture exit. Take the above analysis for consideration,the min- ing-lost water from the aquifer mostly flows through the upper stretch-draw fracture. Finally,the distribution model of water-conducted fracture main channel was built in the light of the breaking size of key strata (KS). The studies pro- vide a theoretical basis to the implementation of artificial control on the water flow in the main channel of water-con- ducted fractures.