【作者】 刘军；

【导师】 阳军生； 邱喜华；

【作者基本信息】 中南大学 ， 建筑与土木工程， 2013， 硕士

【摘要】 摘要：大同至西安铁路客运专线乔家山隧道在DIK436+640～437+100和DIK437+585～438+170穿越第三系粉质粘土地层,该地层自稳能力较差,开挖后变形持续时间长,施工风险高,曾出现围岩大变形导致部分支护结构破坏现象。解决乔家山隧道穿越第三系粉质粘土地层施工技术难题,提出有效的施工风险控制措施,对于确保隧道施工和运营安全具有现实意义。本论文通过第三系粉质粘土物相和微观结构分析、物理力学性质试验,揭示了该地层具有围岩软弱及流变特性,导致隧道产生大变形。通过乔家山隧道施工初期围岩与结构变形现场调查分析,进行了有针对性的隧道穿越第三系粉质粘土地层施工风险评估,明确了施工风险因素,提出了降低施工风险的控制方法,即主要通过增强支护强度、提高预留变形量等措施,在确保初期支护稳定性和衬砌不侵限的前提下,允许初支产生较大变形,让其承担更多的围岩压力,从而让流变引起的主体变形在衬砌施作前完成。为验证乔家山隧道施工风险控制措施实施效果,选取了典型断面,进行隧道开挖后周边收敛测试、围岩与初期支护接触压力测试、以及隧道初期支护和衬砌的受力和变形测试,测试结果显示,采用优化后的隧道支护参数和施工方式,虽然初期支护仍有较大变形,但能确保其稳定性及隧道净空,且隧道衬砌处于安全状态。本文研究成果可为类似流变性地层隧道设计与施工提供参考,具有较高的工程实用价值。文中图31幅,表14个,参考文献60篇。更多还原

【Abstract】 ABSTRACT:Qiaojiashan tunneling engineering is the controlling project of Datong-Xi’an railway passenger-dedicated line, where the tertiary silty clay deposit was encountered at section of DIK436+640～437+100and DIK437+585～438+170, which is notorious for its instability and long-time ground deformation after excavation, and thus brought high risk to Qiaojiashan tunnel construction, like for supporting structure damage due to large deformation of surrounding rock has been confronted. To solve the technical problem that tunneling through the tertiary silty clay formation and to propose controlling measures is of practical significance for guaranteeing tunnel constructing and operating safety.This paper reveals the weakness and rheology characteristics of rock mass of the tertiary silty clay formation by phase and microstructures analysis together with physical and mechanic test, and that rock properties are main contributions to large deformation of tunnel. In-site survey and analysis on deformation characteristic of surrounding rock and supporting structure at initial constructing stage were performed, based on which risk assessment was made on tunneling through the tertiary silty clay formation, almost all constructing risk factors were indicated, and constructing controlling measures were suggested to reduce risk, that is, through enhancing supporting strengthen and increasing allowance deformation to allow elastic liner perform certain deformation and bear more surrounding rock pressure as long as that liner stability and tunnel clearance were guaranteed, so that time-dependent deformation of surrounding rock would finish before installation of permanent lining.Several typical monitoring sections were chosen to verify the validity of the controlling measures proposed. Tunnel convergence, contact pressure between rock and elastic liner, mechanic and deformation characteristic of supporting structure were monitored in-site. The results denote that through optimization of supporting structure and excavation mode the tunnel supporting structure was in safety during constructing stage, and the tunnel clearance together with structural stability were guaranteed though large deformation still occurred in elastic liner. The achievement of this research provided a reference for the design and construction of tunnel excavated through similar rheological formation.31pictures,13charters and60references are presented in this paper.更多还原