预切槽法在黄土隧道中的应用与预切槽结构受力分析

发布时间：2019-03-09 08:22

【摘要】：本文通过数值模拟研究了预切槽法在黄土隧道中的作用,通过对比隧道变形与预切槽结构受力进行对比,分析了预切槽法在黄土隧道中的适用性,为预切槽法在黄土隧道中的应用提供了理论依据。主要工作与研究成果如下：(1)总结了软弱围岩隧道变形控制方法,要重视掌子面超前核心土在隧道变形中的作用,应从超前支护、掌子面加固、脚部补强三个方面加强对于隧道变形控制。(2)通过与全断面黄土隧道开挖方法相比,采用预切槽作为超前支护,可以有效控制隧道洞周收敛、拱顶沉降和地表沉降,预切槽能够减少隧道预收敛变形,但是对于掌子面挤出变形控制效果有限。(3)从隧道埋深、支护时机、开挖进尺三个方面研究了采用20 cm与25 cm厚预切槽时,隧道变形规律与支护结构受力,应该保证支护结构安全满足要求,在隧道开挖时应遵守“快挖、快支”的原则。(4)掌子面玻璃纤维锚杆加固参数(锚杆长度、锚杆搭接长度)是控制掌子面加固效果的关键措施,根据隧道预收敛变形范围确定锚杆长度,根据掌子面破裂面长度确定锚杆最小搭接长度；在预切槽法中,锁脚锚杆不能起到锚固作用。(5)根据掌子面变形规律,可以对掌子面加固范围进行优化,当加固范围较小时,掌子面将发生大范围变形,不利于掌子面稳定性,采用8m加固范围可以满足要求。
[Abstract]:In this paper, the role of pre-shear groove method in loess tunnel is studied by numerical simulation, and the applicability of pre-shear groove method in loess tunnel is analyzed by comparing the deformation of tunnel with the force of pre-shear groove structure. It provides a theoretical basis for the application of pre-cutting channel method in loess tunnel. The main work and research results are as follows: (1) the control methods of tunnel deformation in soft surrounding rock are summarized, and the role of leading core soil in tunnel deformation should be paid attention to, and the advance support and the reinforcement of the palm face should be paid attention to. The three aspects of foot reinforcement strengthen the control of tunnel deformation. (2) compared with the excavation method of full-section loess tunnel, the pre-cutting groove can effectively control the convergence of tunnel surrounding the tunnel, the settlement of arch roof and the settlement of the surface of the tunnel, compared with the excavation method of full-section loess tunnel. The pre-shear groove can reduce the pre-convergence deformation of the tunnel, but the control effect of extrusion deformation on the palm surface is limited. (3) when 20 cm and 25 cm thick pre-shear groove is adopted, the tunnel depth, support opportunity and excavation scale are studied from three aspects: the depth of the tunnel, the time of support and the length of excavation. The deformation law of tunnel and the force of supporting structure should be guaranteed to meet the requirement of safety of supporting structure, and the principle of "fast digging, fast supporting" should be obeyed in tunnel excavation. (4) the reinforcement parameters of glass fiber bolt on the palm face (bolt length, length of anchor bar) should be observed. The bolt lap length is the key measure to control the strengthening effect of the palm face. According to the pre-convergence deformation range of the tunnel, the bolt length is determined, and the minimum lap length of the bolt is determined according to the length of the fracture surface of the palm face. (5) according to the deformation law of the palm face, the reinforcement range of the palm face can be optimized, and when the reinforcement range is small, the palm face will be deformed in a large range, and the anchor bolt will not be able to anchor the anchor in the pre-cutting slot method. (5) according to the deformation law of the palm face, the strengthening range can be optimized. It is not conducive to the stability of the palm surface, and the 8 m reinforcement range can meet the requirements.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U455.4

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