既有隧道扩挖改造的施工控制及数值模拟研究

发布时间：2019-01-01 18:36

【摘要】：研究目的:由于既有人防隧道的扩挖改造施工在国内鲜有实例,本文综合应用监控量测技术和有限元分析理论,模拟研究结构单双侧扩挖动态掘进各阶段的位移、变形及受力特征,并将数值模拟结果与实测结果进行了对比分析,通过完善施工方案并加强施工控制,保证施工安全。研究结论:(1)单、双侧扩挖造成的地表最大沉降值、围岩结构应力等主要指标均满足规范和设计要求,表明制定的施工方案合理;(2)随着整个隧洞的扩挖,围岩结构呈拉应力减小、压应力增加的趋势,其最大拉应力在施作初期支护和临时支撑时剧减,其最大压应力在顶部结构凿除时剧增;(3)单侧扩挖每次凿除2 m既有结构,地表的最大沉降值达到15.10 mm,而双侧扩挖每次凿除1 m既有结构,地表的最大沉降值达到23.67 mm,此值非常接近设计警戒值(24 mm),施工的时候应该严格控制;(4)提出了采用临时竖撑预支加固、先侧墙后仰拱、径向注浆、管棚支护和跳槽扩挖等施工方法和措施,使既有结构内力变化在可控范围内,有效地控制了拱顶沉降、仰拱上浮和地层位移,保障了结构和施工安全;(5)通过总结既有人防隧道扩挖改造施工过程中围岩、地表、衬砌结构等的变形规律,为同类工程的设计和施工提供借鉴。
[Abstract]:The purpose of this paper is to simulate and study the displacement of dynamic excavation of single and double sides of the structure by using the monitoring and measuring technology and the finite element analysis theory, because there are few examples in the construction of the existing civil air defense tunnel. The characteristics of deformation and stress are compared and analyzed between the numerical simulation results and the measured results. The safety of the construction is ensured by perfecting the construction scheme and strengthening the construction control. The conclusions are as follows: (1) the maximum settlement value and surrounding rock structure stress caused by single and double side expansion and excavation all meet the specifications and design requirements, which indicates that the construction scheme is reasonable; (2) with the expansion of the whole tunnel, the surrounding rock structure shows a tendency of decreasing tensile stress and increasing compressive stress. The maximum tensile stress decreases sharply during the initial support and temporary support, and the maximum compressive stress increases sharply when the top structure is chiselled; (3) the maximum settlement value of the ground surface is 15.10 mm, and the maximum settlement value of the ground surface is 23.67 mm, respectively, and the maximum settlement value of the existing structure is up to 15.10 mm, per time, and the maximum settlement value of the ground surface is up to 23.67 mm,. This value is very close to the design alert (24 mm), construction should be strictly controlled; (4) some construction methods and measures are put forward, such as temporary vertical brace advance support, first side wall and then inverted arch, radial grouting, pipe shed support and flanking, so that the change of internal force of the existing structure can be controlled, and the settlement of the arch can be effectively controlled. The inverted arch floats and the stratum displacement, which guarantees the structure and the construction safety; (5) through summing up the deformation law of surrounding rock, surface and lining structure during the construction of the existing civil air defense tunnel, it can provide reference for the design and construction of similar projects.
【作者单位】：华北水利水电大学;中铁七局集团有限公司;
【基金】：国家自然科学基金(51308214)
【分类号】：U455.4

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