济三煤矿正断层下盘开采断层上应力的时空分布数值模拟

Numerical simulation of the spatio-temporal stress distribution on the normal fault for the footwall mining in3-rd Jining Coal Mine

以兖矿集团济三煤矿6303工作面地质条件为背景建立FLAC3D数值模型,开展了数值模拟研究。模型中共包含13个岩层和1个正断层(倾角为45°)。采用界面单元模拟断层接触面和岩层接触面。在断层上布置了22个监测节点,获得了工作面推进过程中断层各处正应力和切应力的时空分布规律。数值模拟结果表明:当工作面煤壁距离断层较近时,断层上存在1个压紧区,该区范围随着工作面推进而减小且该区中心向断层中下部的煤层移动;与此同时,在压紧区后方存在1个松动区,松动区随着工作面推进而沿着断层向下拓展。根据松动区内切应力上升会增加断层滑动危险的认识,确定每两次开采之间的断层滑动危险区段多位于松动区前端。在开采瞬时稍后普遍存在正应力下降现象。根据安全系数下降确定的开采瞬时稍后断层滑动危险区段也多位于松动区前端。

The present paper is aimed at providing for a numerical simulation via the software known as FLAC3 Dto model the fault and the strata contact surfaces in the interface elements.And,for the said goal,the paper has arranged 22 monitoring nodes on the hanging wall of the normal fault and,has,then,obtained the spatio-temporal distribution results of the normal and shear stresses with the working face advancing on.Furthermore,we have also built up a numerical simulated model based on the geological condition of No.6303 working face of Yankuang Group under the Jinan Coal Mine complex.The afforementioned simulated model may include 13 rock strata and 1 normal fault with its dip being of 45°and the coal wall of the working face perpendicular to the mining floor and roof,with the fault throw projected in2 ms.Besides,with the working face advancing on towards the normal fault area from the right boundary of the model on the footwall,it would be possible to obtain the following numerical results,for,as long as the working face is close to the fault area,the normal fault should be lying at the intersection line between the stress shell and the fault area,where the compressing zone should be situated.And,the compressing size of the zone tends to be getting decreased as the working face is advancing on,whose central exploitation zone tends to move towards the coal seam at the middle and lower portion of the fault area.At the same time,there would follow a loosening zone behind the compressing zone,whose front should be situated in the front of the coal wall of the working face.And,henceforth,the loosening zone should be moving downwards along the fault area as the working face is advancing.And,now,seeing that the increase of the shear stress in the loosening zone may aggrevate the dangerous risk extent of the fault slip,the dangerous fault segments that can be forecast and determined mainly lie in front part of the loosening zone between the 2 excavations.Thus,the decreasing normal stresses can be found immediately once each excavation action is completed instantaneously.And,also,the dangerous fault segments that can be determined as the result of each instantaneous excavation should be mainly concentrated,too,in front of the loosening zone according to the each decrease of the safety factor.