【摘要】：華坪隧道是麗攀高速公路僅有的穿越于攀西地區(qū)昔格達地層的隧道,也是所有昔格達地層中僅有的高速公路隧道。華坪隧道圍巖穩(wěn)定性研究不僅可以對隧道施工設計提供參考,同時其研究成果也可應用到其他昔格達地層中的公路隧道。因此,課題組有必要對華坪隧道的圍巖穩(wěn)定性進行深入的分析和研究。本文以麗攀高速公路華坪隧道為研究對象,首先通過收集資料、野外勘查及室內土工試驗,掌握了隧道的工程地質背景,進而開展了對昔格達地層隧道圍巖穩(wěn)定性的離心模型試驗研究。課題采用模型試驗方法,用離心力代替山體應力,模擬隧道開挖后可能出現(xiàn)的圍巖變形破壞及地質病害。本課題共進行了三組對比試驗,通過布設觀測點、應變數據曲線分析、數據插值分析,研究不同巖性、巖層結構、節(jié)理發(fā)育情況及支護措施對圍巖穩(wěn)定性的影響,進而探索圍巖變形破壞規(guī)律,預測隧道變形情況和可能產生的地質病害,為在施工過程中及時采取措施應對地質病害提供了理論支持。主要研究內容及成果如下：(1)離心力模擬山體自重應力作用于模型洞室圍巖,當洞室開挖后,圍巖原有應力平衡狀態(tài)被打破,形成圍巖應力重分布,在新的圍巖應力狀態(tài)下,圍巖產生松脹變形。(2)隧道模型圍巖聚集大量能量,呈向內擠壓趨勢；且愈向自由表面(洞室周邊)接近,能量愈集中,至洞室周邊處達到最大值；其中洞壁拱頂位置能量最為集中,應變最大。(3)主應力分異效應使得拱頂表現(xiàn)為拉應力集中,邊墻表現(xiàn)為切向壓應力集中圍巖應力釋放,使圍巖各質點向洞室內部回彈變形。當拱頂圍巖應力大于抗拉強度時,產生張裂塌落現(xiàn)象。(4)由于洞壁圍巖應力集中,當隧道圍巖發(fā)育軟弱結構面時,不利于圍巖的穩(wěn)定性,易發(fā)生坍塌。特別在斷層影響帶,巖體發(fā)育有傾向于掌子面外的結構面時,易沿結構面產生掌子面滑塌,發(fā)育為結構面控制型的圍巖變形破壞。(5)錨桿加固圍巖使其整體性增強,層間摩阻力增大,抗拉強度增大,從而增加圍巖穩(wěn)定性,縮小圍巖塑性區(qū)范圍,減小圍巖應變。實驗結果表明現(xiàn)場錨桿參數以取長度4.5m,間距0.75cm為宜。(6)昔格達地層華坪隧道圍巖范圍為2倍洞徑,超過2倍洞徑應變很小。洞室間距為2倍洞徑時,圍巖之間無明顯的相互影響。(7)由于采用鋼拱架支護可以起到環(huán)形封閉的作用,避免出現(xiàn)掉拱等拱架失穩(wěn)現(xiàn)象的發(fā)生。因此,在施工工程中,建議采用鋼拱架支護圍巖,根據實驗中圍巖掉塊的結果,說明鋼拱架間距設置應取0.5米為宜。
[Abstract]:Huaping Tunnel is the only tunnel in Lifan Expressway that passes through Xigeda formation in Panxi area, and it is also the only highway tunnel in Xigeda formation. The study of surrounding rock stability of Huaping tunnel can not only provide reference for tunnel construction design, but also be applied to other highway tunnels in Xigeda formation. Therefore, it is necessary to analyze and study the surrounding rock stability of Huaping Tunnel. In this paper, the Huaping Tunnel of Liupan Expressway is taken as the research object. Firstly, the engineering geological background of the tunnel is grasped by collecting data, field exploration and indoor geotechnical test. The centrifugal model test of surrounding rock stability of Xigeda formation tunnel is carried out. In this paper, the model test method is used to simulate the deformation and failure of surrounding rock and geological diseases after tunnel excavation by using centrifugal force instead of mountain stress. Three groups of comparative tests were carried out in this paper. By setting up observation points, analyzing strain data curve and data interpolation analysis, the effects of different lithology, rock structure, joint development and supporting measures on the stability of surrounding rock were studied. Furthermore, the rules of surrounding rock deformation and failure are explored, and tunnel deformation and possible geological diseases are predicted, which provides theoretical support for timely measures to deal with geological diseases in the construction process. The main research contents and results are as follows: (1) the centrifugal force simulates the gravity stress of the mountain body acting on the surrounding rock of the model cavern. When the tunnel is excavated, the original stress balance state of the surrounding rock is broken, and the stress redistribution of the surrounding rock is formed, under the new surrounding rock stress state, (2) the surrounding rock of the tunnel model accumulates a large amount of energy and tends to squeeze inward, and the closer the free surface (surrounding the cavern) is, the more concentrated the energy is, and the maximum energy is reached to the periphery of the tunnel. Among them, the energy concentration is the most concentrated and the strain is the largest in the arch roof. (3) the main stress differentiation effect makes the arch roof appear as tensile stress concentration, and the side wall shows tangential compression stress concentration surrounding rock stress release, which makes the surrounding rock particles rebound to the interior of the cavern. When the stress of the arch roof wall rock is greater than the tensile strength, the phenomenon of tensile crack collapse occurs. (4) because of the stress concentration in the wall rock of the tunnel, when the tunnel wall rock develops a weak structural plane, it is unfavorable to the stability of the surrounding rock and prone to collapse. Especially in the fault influence zone, when the rock mass develops the structural plane which tends to be out of the face, it is easy to collapse along the structural plane and develop into the deformation and failure of the surrounding rock controlled by the structural plane. (5) strengthening the surrounding rock with anchor rod to enhance its integrity. With the increase of interlayer friction resistance and tensile strength, the stability of surrounding rock is increased, the range of plastic zone of surrounding rock is reduced, and the strain of surrounding rock is reduced. The experimental results show that the parameters of anchor rod in the field are 4.5m in length and 0.75cm spacing. (6) the surrounding rock area of Huaping tunnel in Xigeda formation is 2 times diameter, and the strain over 2 times diameter is very small. There is no obvious interaction between the surrounding rock when the space between the caverns is 2 times the diameter. (7) because the steel arch support can play the role of annular closure, the phenomenon of arch instability such as falling arch can be avoided. Therefore, in the construction project, it is suggested that the steel arch frame should be used to support the surrounding rock, and according to the results of the surrounding rock falling in the experiment, it is suggested that the distance between the steel arches should be set at 0.5 meters.
【學位授予單位】：西南交通大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：U451.5

【參考文獻】

相關期刊論文 前2條

1 馬亮,高波;隧道施工地表沉降控制的離心模型試驗[J];施工技術;2005年06期

2 郭昭,王景銘,張師德;土工離心模擬試驗的應變分析[J];上海鐵道大學學報;1997年04期

，

本文編號：2151642