对公路隧道施工过程的力学分析及其数值模拟

发布时间：2018-07-26 08:13

【摘要】：虽然公路隧道工程的建设发展速度迅猛,但公路隧道相关理论及设计、施工技术的实践研究仍不够深入,本文依托某工程实例[1],对隧道中初期支护、二次衬砌两者的受力机理作深入研究;在改变二次衬砌刚度大小的情况下,研究二次衬砌厚度、弹性模量、泊松比以及隧道不同的埋深、改变两隧道间距离对支护体系受力性状的影响。用有限元软件FLAC[2]对该隧道作详细开挖支护数值分析,了解不同工况下隧道支护体系的内力和变形,发现左右隧道两个洞室存在相互影响;隧道中拱顶、拱腰处、仰拱中部都是受力中较为不利的薄弱位置,在设计时要做局部加强,施工时也要注意支护;通过对监测变量的分析,最大不平衡力最终趋于收敛,左右隧道支护体系拱顶的位移趋于稳定。当支护体系中二次衬砌的刚度变化时,随着二次衬砌厚度的增加,在拱顶、拱腰、拱脚处二次衬砌中围岩应力基本成线性增大,但当厚度到650mm时增加的速率有所减缓;而在拱肩处二次衬砌的应力变化大小不一,规律性不强;随着弹性模量的增加,会使拱腰、拱肩处二次衬砌中压应力变大,基本呈现线性变化,而对拱顶、拱脚处基本无影响;当改变泊松比的大小,对支护体系中二次衬砌的应力大小基本无影响;当二次衬砌的刚度增大时,不一定就会使得二次衬砌所分担的围岩压力有所增加,因为复合式衬砌的受力较为复杂,此时,还要继续分析影响刚度大小的具体因素。随着隧道埋深的增大,围岩的自重应力会相应增加,隧道支护体系中初期支护所受的围岩压力增大,这与我们主观感受的也相一致,而且增加的速率越来越快,二次衬砌的受力基本不变。随着左、右两隧道之间的距离增加时,右隧道对左隧道的影响减小,左隧道支护体系的受力减小,两隧道间的相互影响逐渐减弱。
[Abstract]:Although the construction of highway tunnel project is developing rapidly, the practical research on relevant theory and design and construction technology of highway tunnel is still not deep enough. This paper relies on an engineering example [1] to support the tunnel in the early stage. Under the condition of changing the stiffness of the secondary lining, the thickness, elastic modulus, Poisson's ratio and the different buried depth of the tunnel are studied. The influence of changing the distance between two tunnels on the mechanical behavior of supporting system. By using finite element software FLAC [2], the numerical analysis of the excavation and support of the tunnel is carried out in detail, and the internal force and deformation of the tunnel support system under different working conditions are understood, and it is found that the two caverns in the left and right tunnels have mutual influence on each other. The middle part of the inverted arch is the weak position in the stress, so it is necessary to strengthen it locally and to pay attention to the support in the construction. Through the analysis of the monitoring variables, the maximum unbalanced force tends to converge finally. The displacement of the vault of the left and right tunnel support system tends to be stable. When the stiffness of the secondary lining in the support system changes, with the increase of the thickness of the secondary lining, the stress of surrounding rock in the secondary lining at the arch top, arch waist and arch foot basically increases linearly, but the increase rate of the secondary lining increases slightly when the thickness reaches 650mm. With the increase of elastic modulus, the compressive stress in the arch waist and the secondary lining at the arch shoulder will become larger, showing a linear change, but there is no effect on the arch top and the arch foot, while the stress of the secondary lining at the arch shoulder is different, and the regularity is not strong, and with the increase of the elastic modulus, the compressive stress in the arch waist and the secondary lining at the arch shoulder will become larger and present a linear change. When the Poisson's ratio is changed, the stress of the secondary lining in the support system is not affected, and when the stiffness of the secondary lining is increased, the surrounding rock pressure of the secondary lining is not necessarily increased. Because the force of composite lining is more complicated, we should continue to analyze the specific factors that affect the stiffness. With the increase of the buried depth of the tunnel, the gravity stress of surrounding rock will increase accordingly, and the surrounding rock pressure of the initial support in the tunnel support system will increase, which is consistent with our subjective feelings, and the increasing rate is getting faster and faster. The force of the secondary lining is basically unchanged. With the increase of the distance between the left and right tunnels, the influence of the right tunnel on the left tunnel decreases, the force of the left tunnel support system decreases, and the interaction between the two tunnels weakens gradually.
【学位授予单位】：山东建筑大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U415;U455

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