何开伟

摘 要：广东省东北部山区分布着大量的花岗岩地层，部分洞身处于浅埋偏压的不利状态下，全风化花岗岩富水隧道的稳定性差，开挖过程中掌子面难以自稳，注浆加固是保证隧道开挖安全的重要手段。本文以梅汕铁路大岭隧道溜塌段为研究对象，通过分析该段全风化花岗岩的成分及崩解特性，得到溜塌的原因，采用前进式（或后退式）注浆+多管注浆及后期地表注浆联合加固技术。隧道施作效果表明，该综合加固施工措施有效解决了全风化花岗岩段透水性强、遇水软化、掌子面难以自稳、初期支护变形大的难题。

关键词：全风化花岗岩;富水隧道;浅埋偏压;帷幕注浆;地表注浆

中图分类号：U455.4文献标识码：A文章编号：1003-5168（2021）05-0096-04

Abstract： A large number of granite strata are distributed in the northeast mountainous area of Guangdong Province. The tunnel portal sections are often in the unfavorable state of shallow buried bias pressure. The stability of fully weathered granite water rich tunnel is poor， and the tunnel face is difficult to be stable during excavation. Grouting reinforcement is an important measure to ensure the safety of tunnel excavation. This paper took Daling tunnel of Meizhou-Shantou railway as the research object. Based on the analysis of the composition and disintegration characteristics of the completely weathered granite in this section， the causes of the collapse were obtained. This paper analyzed and introduced the combined reinforcement technology of forward （or backward） grouting， multi pipe grouting and later surface grouting. The final tunnel construction results show that the comprehensive reinforcement measures effectively solve the problems of strong water permeability， softening in water， difficult to stabilize the face， and large deformation in the initial support.

Keywords： completely weathered granite;enriched water tunnel;shallow buried bias;curtain grouting;surface grouting

隨着我国交通基础工程的进一步完善，越来越多的铁路、公路向地质条件更加复杂的山区延展，浅埋偏压隧道工程在丘陵山区斜坡地段公路、铁路建设过程中往往不可避免，而浅埋偏压隧道开挖引起的围岩扰动较深埋隧道更加复杂，而且遇到全风化花岗岩这类软弱围岩时，隧道的稳定性问题就成为施工中巨大的挑战，历来都是研究的热点问题[1-2]。针对浅埋隧道掌子面的问题，国外众多学者[3]从二维、三维的角度进行了一定分析，在破坏模型、滑移机理、弹塑性区域的应力分布规律、地表沉降规律及分布特征等方面取得了大量研究成果。全风化花岗岩往往呈现出散体的形态，整体工程特性表现为孔隙率大、胶结性差、崩解性显著、含水率高时呈流塑性及施工时易被扰动，开挖过程中掌子面常出现滑塌，初期支护变形量大，二次衬砌施作后也易开裂。……