小断面硐室突变大断面硐室施工过程拱顶沉降有限元分析

Finite Element Analysis of Crown Settlement During the Construction Process from Small to Large Section Adit:A Case Study of Qitou Mountain Mine Project,Sanmen County,Taizhou City

为解决现有小断面突变大断面硐室开挖工程中围岩变形大、难控制的难题,本文以台州市三门县其头山矿山项目为工程背景,在提出中导洞及侧壁导洞反向爬坡开挖法的基础上,采用Plaxis2d软件对两种开挖方式下小断面硐室突变大断面硐室的施工过程进行了有限元模拟。结果表明:对于大、小断面硐室,侧壁导洞爬坡开挖法的拱顶下沉量分别略高于中导洞8.0%及5.0%左右;考虑到单炮进尺过小带来的施工效率低以及过大带来的安全性差问题,对于小断面硐室,单炮进尺应控制在2.5 m,侧壁/中导洞开挖时的单日爆破次数均不得超过2次;对于大断面硐室,单炮进尺应控制在3.0 m,侧壁/中导洞开挖时的单日爆破次数不得超过3次及2次。

This paper focuses on the Qitou Mountain mining project in Sanmen County,Taizhou City,employing Plaxis2d for the simulation of the excavation process from small to large section adits.The results indicate that for large and small section adits,the crown settlement amount during sidewall pilot tunnel climbing excavation method is approximately 8.0%and 5.0%higher than that of the middle pilot tunnel,respectively.Considering the low construction efficiency caused by too small single-round advance and the poor safety associated with too large single-round advance,for small section adits,the single-round advance should be controlled at 2.5 m,with the number of daily blasts during sidewall/middle pilot tunnel excavation not exceeding two times;for large section adits,the single-round advance should be controlled at 3.0 m,with the number of daily blasts during sidewall/middle pilot tunnel excavation not exceeding three and two times,respectively.