进路分步开挖背景应力场演化规律研究

鲁中小官庄铁矿由于埋藏深、地压大、矿体倾角比较缓、矿岩破碎，是国内有名的难采矿山之一。进路开挖以后支护巷道破坏严重，其围岩变形为无收敛变形，也是国内支护较难的矿山之一。针对小官庄铁矿情况，为掌握其地压活动规律，应用东北大学岩石破裂过程分析系统（RFPA），模拟其采用无底柱分段崩落法进路开挖过程，对进路开挖过程巷道围岩应力变化进行数值分析。发现随着进路开挖，导致进路出现片帮、底鼓、顶板下沉等现象，并且在矿岩接触带出现高应力集中，导致两进路之间的间柱破坏严重，并随着进路开挖应力逐步向新开挖两进路之间的间柱转移，开挖顺序造成边界矿体出现高应力集中，导致边界矿体难采。数值分析结果可以看出：进路的开挖顺序是导致小官庄铁矿进路围岩破坏的一个主要原因。

Study on evolvement law of background stress field of multi-step excavation of roadway

Because of the deep embedding,high underground pressure and fragmentation of ore and rockmass,the Xiaoguanzhuang Iron Mine is one of the most difficult excavation iron mine in China.The study results in recent years indicate that the rockmass of Xiaoguanzhuang Iron Mine has the creep characteristic.After the roadway was excavated,the destruction of supporting roadway is very severe.The deformation of roadway is no convergence deformation;and the iron mine is difficult support mine.According to the field condition,in order to know the distribution law of underground pressure,we used the rock failure process analysis(RFPA),in which the creep evolvement model is drawn into the numerical model,to model the excavation process of roadway by adopting the non-pillar sublevel caving;and numerically analyze the stress distribution of surrounding rock.We found that the surrounding rock occur the creep deformation along with time when the roadway is caving.Because of the creep deformation of roadway,the destruction of roadway is mainly rib spalling,floor heave and roof falling etc..At the same time,the high stress concentration leads to the severe destruction of pillar between two roadways.Along with the caving of roadway,the stress diverts into surrounding roadway of the newly caved roadway.Because of the multi-step caving,the high stress convergence occurs in the boundary ores,which leads to the difficult excavation of boundary ore.The numerical result is in accordance with the result of field investigation.From the numerical result we concluded that the creep characteristic of rockmass and the multi-step excavation mainly lead to the destruction of roadway.