黄土隧道锁脚锚管作用机理及承载特性研究

发布时间：2018-04-18 23:06

本文选题：黄土隧道 + 锁脚锚管　；参考：《兰州交通大学》2015年硕士论文

【摘要】：锁脚锚管作为控制隧道变形的一种重要的支护手段,在黄土隧道的施工过程中得到了广泛的应用。为了深入认识黄土隧道锁脚锚管的支护作用机理与其承载特性,本文在现有研究成果的基础上,分析其支护作用机理,并通过数值模拟的分析方法对其承载特性与工作状态进行了研究。在结合黄土隧道锁脚锚管作用机理的基础上探讨了黄土隧道锁脚锚管的施工工艺及注意事项。主要结论如下:⑴结合黄土自身地质特点与系统锚杆的作用原理总结分析了黄土隧道锁脚锚管的荷载分布以及支护作用机理。黄土隧道锁脚锚管主要通过其支承作用将初期支护与围岩联结成整体以改善其支护效果,通过其围岩加固作用提高黄土的自稳能力,两方面作用相结合从而充分发挥初期支护承载作用。⑵通过对不同工况(L=3~5m、θ=10°~30°、D=42.5mm或89.0mm)锁脚锚管竖向承载力数值模拟分析发现,提高锁脚锚管长度、下斜角度以及增大管体直径对提高锚管承载力、减小土体变形与土体塑性应变等方面具有明显效果。⑶结合王家沟隧道开挖支护方法,通过不同工况锁脚锚管对隧道变形影响的模拟分析发现:提高锁脚锚管长度对改善控制围岩变形效果明显;增大锁脚锚管下斜角度能够有效控制围岩竖向位移,较小的锁脚锚管下斜角度有利于控制隧道水平收敛;提高锁脚锚管直径对改善支护效果具有一定的作用,但效果差别并不显著。由于初期支护传递至锁脚锚管的竖向荷载主要由上台阶锁脚锚管所承受,结合施工方面因素的考虑,建议在黄土隧道上台阶锁脚锚管采用工况θ=30°、l=5m、D=42.5mm;中台阶与下台阶采用θ=10°、l=5m、D=42.5mm;以上工况中锁脚锚管每组均施作四根。⑷黄土隧道锁脚锚管施工过程中应严格按照设计方案进行,基于黄土隧道特殊地质情况,锁脚锚管需采用干法施工,并控制好注浆与焊接质量,以确保其承载能力能够充分发挥。
[Abstract]:As an important supporting method to control tunnel deformation, anchor pipe with locking foot has been widely used in the construction of loess tunnel.In order to deeply understand the supporting mechanism and bearing characteristics of anchor pipe with locking foot in loess tunnel, this paper analyzes its supporting mechanism on the basis of existing research results.The load-bearing characteristics and working state are studied by numerical simulation.Based on the action mechanism of anchor pipe with locking foot in loess tunnel, the construction technology and matters needing attention of anchor pipe with locking foot in loess tunnel are discussed.The main conclusions are as follows: (1) combined with the geological characteristics of loess and the action principle of system anchor, the load distribution and supporting mechanism of anchor pipe with locking foot in loess tunnel are summarized and analyzed.In order to improve the supporting effect, the anchor pipe with locking foot in loess tunnel can improve the supporting effect by connecting the initial support with surrounding rock, and improve the self-stability ability of loess by strengthening the surrounding rock.Through numerical simulation analysis on the vertical bearing capacity of anchor pipe with locking foot under different working conditions (L3 ~ 3m, 胃 ~ 10 掳~ 30 掳D ~ (2 +) 42.5mm or 89.0mm), it is found that the length of anchor pipe with locking foot can be increased.The inclined angle and the increase of the diameter of the pipe body have obvious effect on improving the bearing capacity of the anchor pipe, reducing the deformation of the soil and plastic strain of the soil, and combining with the excavation and supporting method of the Wangjiagou tunnel.Through the simulation analysis of the influence of locking anchor pipe on tunnel deformation under different working conditions, it is found that increasing the length of lock foot anchor pipe has obvious effect on improving the deformation of surrounding rock, increasing the downslope angle of lock foot anchor pipe can effectively control the vertical displacement of surrounding rock.The lower angle of anchor pipe with locking foot is helpful to control the horizontal convergence of tunnel, and the increase of diameter of anchor pipe with locking foot can improve the supporting effect, but the difference is not significant.Since the vertical load transferred from the initial support to the anchor pipe with locking feet is mainly borne by the anchor pipe with locking foot on the upper steps, considering the construction factors,It is suggested that the working conditions 胃 ~ (30 掳/ L) ~ (5) m ~ (-1) DX _ (42.5mm) should be adopted in the upper steps of loess tunnel and 42.5mm in the middle and lower steps, and that each group of locking foot anchors in the above working conditions should be carried out strictly in accordance with the design scheme during the construction of four locking foot anchors in loess tunnels.Based on the special geological conditions of loess tunnel, the anchor pipe with locking foot should be constructed by dry method, and the quality of grouting and welding should be controlled well, so as to ensure the full exertion of its bearing capacity.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U455.7

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