石膏质岩隧道工法优选

Excavation Method Optimization of the Gypsum Rock Tunnel

石膏质岩的膨胀特性严重影响隧道的施工设计及其后期的正常使用,目前该类岩体隧道的设计施工大都偏保守,合理的隧道工法是石膏质岩体隧道安全稳定的有力保障。以重庆梁忠高速公路礼让隧道石膏段为工程依托,采用数值模拟,进行工法优选并提出相应施工要求,得出以下结论:(1)对石膏段隧道采用全断面法开挖,支护结构受力最大,变形相对也更大,单侧壁导坑法支护受力最小,变形相对要小,但工序复杂,上下台阶法工序相对简单,变形及受力在允许范围内。(2)选取断面进行台阶法开挖现场测试,提出开挖阶段严格控制爆破及仰拱及掌子面间距,并加强各类支护,加深仰拱等相应现场要求。(3)现场测试结果显示隧道变形实测值较模拟数值稍有偏小,隧道整体偏安全,礼让隧道石膏段采用上下台阶法开挖可行。研究成果对类似石膏质岩隧道提供了有益借鉴。

The expansion features of the gypsum rocks seriously affect the construction of the tunnel design and its normal use in the late period, the design and construction of these tunnels are mostly conservative at present, Reason- able construction methods are powerful guarantees for gypsum rock tunnels＇ safety and stability. As the gypsum rock section of Lirang tunnel in Chongqing, Liang Zhong highway for the project, using the numerical simulation, to opti- mize the construction method and put forward something requirements, the conclusions are as follows： （1）when the gypsum section tunnel excavated by the whole section method, the supporting structure is largest forced, the tunnel de- formation is relatively more, the supporting force is minimal when the tunnel excavated by the CD method, deforma- tion is relatively smaller, while the process is complicated, up and down the steps method procedure is relatively simple, also the deformation and stress in the allowed range. （2）Select some sections to have a field test with steps method, put forward that the excavation process should strictly controlled blasting and the distance between the inverted arch and constraints spacing, besides, all kinds of the support should be strengthen, also the inverted arch should he deepen and other corresponding requirement on site. （3）The field test results show that the measured values of the tunnel deforma- tion are slightly smaller than the simulation values, the tunnel is in a good security, it is feasible of the Gypsum tunnel section excavated by steps method. Research provides useful reference for similar gypsum rock tunnel.