超埋深竖井破碎围岩稳定控制技术

Stability control technology of over-buried depth shaft with broken surrounding rock

目前我国金属矿山的最大开拓深度正逐步迈入1500~2000 m,深部“三高”软破围岩下竖井施工工艺合理调整与施工安全的综合评估是制约超埋深竖井安全高效施工的难点。以国内某超埋深破碎围岩竖井工程为研究对象,得出在开挖卸荷引起的围岩切向集中应力作用下,最小主应力方向井壁附近围岩的局部剥落和垮塌是竖井施工应重点关注的风险源。掘进段高由4 m调整为3 m时,掘进时最危险部位为井壁接茬下部1.5 m内,分布深度约1.1 m;掘进段高为2.5 m时,掘进工序时最危险部位为井壁接茬下部1.0 m内,分布深度约0.7 m,改善了掌子面侧壁围岩维护状况。超前小导管、超前钢管约束砼以及钢拱架+超前钢管约束砼等超前支护,仅起到超前防护、防止局部围岩大范围连续垮塌的作用,可增加施工期间安全性,但对围岩的超前支护和加固效果甚微。综合结合掌子面超前探水进行工作面预注浆工作,可减小小导管注浆频繁施工工序切换对施工组织和工期的影响的同时,解决超埋深竖井遇破碎围岩施工安全问题。

At present,the maximum development depth of metal mines in China is gradually stepping into the range of 1500~2000 m.Reasonable adjustment of shaft construction technology and comprehensive evaluation of construction safety under deep"three high"soft broken surrounding rock are the difficulties restricting the safe and efficient construction of over-buried depth shaft.Taking a shaft project of broken surrounding rock with excessive buried depth in China as the research object,it is concluded that under the action of tangential concentrated stress caused by excavation and unloading,the local spalling and collapse of surrounding rock near the shaft wall in the direction of minimum principal stress are the risk sources that should be paid more attention to during shaft construction.When the height of the tunneling section is adjusted from 4 m to 3 m,the most dangerous part of the tunneling process is within the range of 1.5 m below the shaft wall stubble,and the distribution depth is~1.1 m.When the height of the tunneling section is 2.5 m,the most dangerous part of the tunneling process is in the range of 1.0 m below the shaft wall stubble,and the distribution depth is~0.7 m,which improves the maintenance status of the sidewall surrounding rock of the face.Advanced support,such as advanced small conduit,advanced concrete confined by steel tube,steel arch,and advanced concrete confined by steel tube,can only play the role of advanced protection and prevent large scale continuous collapse of local surrounding rock,and can increase the safety during the construction period,but has little effect on the advanced support and reinforcement of surrounding rock.The pre-grouting work of the working face can reduce the influence of frequent construction procedure switch of small pipe grouting on construction organization and time limit,and solve the construction safety problem of broken surrounding rock encountered by over-buried depth shaft.