本文選題：淺埋偏壓　切入點：小間距　出處：《重慶交通大學》2015年碩士論文

【摘要】：本文以武深高速公路小方山隧道為依托,以高速公路隧道圍巖一結構穩(wěn)定性分析為主線,以指導和提升小方山隧道的優(yōu)化設計及安全施工為目的,分別運用定量評價、定性評價、整體評價以及局部評價相輔相成的方法,對小方山隧道圍巖一結構的整體穩(wěn)定性進行系統(tǒng)的分析。主要有以下幾點內容:①荷載作為圍巖—結構穩(wěn)定的一項重要指標,本文結合公路隧道規(guī)范中淺埋隧道和偏壓隧道的荷載計算原理與公式,經(jīng)過分析推導后得到淺埋偏壓同時存在情況下小間距隧道的荷載計算方法。在推導的計算公式基礎上深入淺出地得到小間距隧道僅在淺埋情況下的荷載計算公式。②運用同濟曙光軟件模擬了小方山隧道的施工全過程。采取了先左洞后右洞和先右洞后左洞這兩種施工次序的上下臺階法施工,分別得到了這兩種施工次序的圍巖以及支護結構的受力及變形情況,通過對比得到在淺埋偏壓段宜選擇先開挖右洞更利于工程的安全施工。同樣對淺埋非偏壓段進行了數(shù)值模擬,得到了圍巖與支護結構的受力位移等情況。將其結果與淺埋偏壓段的對比,得到了偏壓情況下,無論是圍巖最大主應力、圍巖屈服區(qū)范圍深度以及支護結構受力情況都偏向于深埋一側較大,即出現(xiàn)左側(深埋側)大于右側、左洞大于右洞的情況。而在淺埋非偏壓情況下,左右洞的圍巖及支護結構的受力和變形大致處于對稱分布。③使用上下臺階法和全斷面法兩種不同的施工方法對深埋段Ⅳ級圍巖進行數(shù)值模擬分析,分別得到了兩種施工方法的圍巖與支護結構在各施工步的應力及變形情況,得到的結果是在圍巖性質不太好的Ⅴ級及Ⅳ級圍巖宜選取臺階法施工,在圍巖好的Ⅳ級和Ⅲ級圍巖中可選擇全斷面法施工。而此深埋段Ⅳ級圍巖處宜采取臺階法施工。④討論分析了應力釋放系數(shù)對二襯的影響。采取施作二襯時不同的圍巖應力釋放系數(shù)建模分析后比較其內力與變形,得到了在釋放系數(shù)不斷加大,圍巖的拱頂豎向位移和拱腰水平相對位移均在減小,二襯拱頂和拱腰處軸力一直增大,二襯彎矩和剪力先增大然后在釋放系數(shù)達到20%以后趨于穩(wěn)定。這為現(xiàn)場施作二襯時間做出參考,也能對相似工程有所參考意義。
[Abstract]:Based on the Xiaofangshan Tunnel of Wu-Shen Expressway, the main line of this paper is the stability analysis of the surrounding rock structure of the expressway tunnel, with the aim of guiding and promoting the optimization design and safe construction of the Xiaofangshan Tunnel, the quantitative evaluation is used respectively. Qualitative evaluation, integral evaluation and local evaluation complement each other to systematically analyze the overall stability of the surrounding rock structure of Xiaofangshan Tunnel. The main contents are as follows: 1 load as an important index of the stability of the surrounding rock structure. This paper combines the principle and formula of load calculation of shallow tunnel and bias tunnel in highway tunnel code. After the analysis and deduction, the load calculation method of the tunnel with small spacing in the presence of shallow bias voltage is obtained. Based on the derived calculation formula, the load calculation formula of the tunnel with small spacing is obtained only in the case of shallow burying. Using Tongji dawning software, the whole construction process of Xiaofangshan Tunnel is simulated. The upper and lower step method is used to construct the first left hole then the right hole and the first right hole after the left hole. The stress and deformation of the surrounding rock and the supporting structure in these two construction sequences are obtained respectively. By comparison, it is concluded that the right hole should be excavated first in the shallow burying bias section is more beneficial to the safe construction of the project. The numerical simulation of the shallow burying unbiased section is also carried out. The stress displacement of surrounding rock and supporting structure is obtained. The results are compared with those of shallow burying section, and the maximum principal stress of surrounding rock is obtained under the condition of bias. The depth of the yield zone of surrounding rock and the stress of the supporting structure tend to be larger in the deep buried side, that is, the left side (deep buried side) is larger than the right side, and the left hole is larger than the right hole. The stress and deformation of surrounding rock and supporting structure of left and right cavern are approximately symmetrical distribution .3 numerical simulation analysis of deep buried section 鈪，

本文編號：1665860