LD公路隧道开挖施工方案优化对比研究

Comparative Study of Construction Sheme Otimization for Excavation of LD Tunel

LD改线公路隧道出口段,属于涉铁1km范围内,对隧道施工有严格要求,且天窗期严重影响施工进度,因此该施工段不宜采用爆破施工,现场采用徐工XTR6/280悬臂掘进机进行隧道开挖.调研国内外铣挖施工研究成果,并依托LD隧道铣挖法施工现场测试试验,得到适合LD隧道铣挖法施工的地质条件,并通过松动圈试验、初支结构受力试验以及数值分析对比相同地质下悬臂掘进机施工与爆破法施工对围岩扰动的影响.实验结果表明,当LD隧道的地质条件为岩石抗压强度小于40 MPa、岩体完整系数小于0.2、岩石质量指标RQD小于20%、岩体体积节理数大于30条/m^(3)、地下水不(弱)发育时,悬臂掘进机掘进速率高于爆破法施工,且悬臂掘进机施工对围岩的扰动远小于爆破法施工.引水隧道与LD改线公路隧道地质情况相似,可为引水隧洞涉铁部分及相似工程提供参考依据.

LD reroute highway tunnel exit section belongs to the railway within 1 km,which has strict requirements for the tunnel construction.And the window period seriously affects the construction progress,so the construction section is not suitable for blasting construction,the site using XCMG XTR6/280 cantilever tunneling machine for tunnel excavation.This paper investigates the research results of milling construction at home and abroad,and relies on the LD tunnel milling construction site test experiments to get the geological conditions suitable for LD tunnel milling construction.And through the loosening circle test,the initial support structure force test,and numerical analysis,the impact of the cantilever tunneling machine construction and blasting construction was compared under the same geology on the surrounding rock disturbance.The experi-mental results show that when the geological conditions of the LD tunnel are rock compressive strength less than 40 MPa,rock integrity coefficient less than 0.2,rock quality index RQD less than 20%,the number of volu-metric joints in the rock is more than 30/m^(3),and groundwater is not(weakly)developed,the cantilever boring machine boring rate is higher than that of blasting method construction,and the disturbance of the surrounding rock by the construction of the cantilever boring machine is much smaller than that of blasting method construc-tion.The diversion tunnel is similar to the LD reroute highway tunnel,which can provide a reference basis for the railway-related part of the diversion tunnel and similar projects.