【摘要】：淺埋隧道的圍巖松散破碎，節(jié)理裂隙發(fā)育，使得圍巖容易發(fā)生失穩(wěn)破壞，開(kāi)挖過(guò)程中常出現(xiàn)冒頂、塌方、突水等不良災(zāi)害；隧道偏壓效應(yīng)使得襯砌結(jié)構(gòu)受力失衡，引起初期支護(hù)和二次襯砌的開(kāi)裂，降低隧道結(jié)構(gòu)的承載能力并破壞防排水系統(tǒng)，導(dǎo)致在運(yùn)營(yíng)過(guò)程中可能出現(xiàn)滲水等不良病害；而隧道開(kāi)挖寬度的增大更加劇了圍巖與襯砌結(jié)構(gòu)的不穩(wěn)定性。因此淺埋偏壓大跨度隧道的圍巖穩(wěn)定分析與施工風(fēng)險(xiǎn)評(píng)估成為亟需解決的問(wèn)題。 以廣深沿江高速宴崗隧道為工程背景，對(duì)不同凈距的淺埋偏壓隧道進(jìn)行了數(shù)值模擬；采用模糊層次分析法與基于可拓理論的評(píng)估物元模型，對(duì)淺埋偏壓大跨度隧道進(jìn)行了風(fēng)險(xiǎn)評(píng)估；并采用地質(zhì)統(tǒng)計(jì)學(xué)中的克里格法對(duì)大跨度隧道的圍巖穩(wěn)定性進(jìn)行了可靠度分析。本文主要取得了如下成果： （1）研究了淺埋偏壓大跨度隧道的力學(xué)特征與破壞模式，并通過(guò)FLAC3D軟件，分析了不同因素對(duì)隧道穩(wěn)定性的影響。結(jié)果表明:由于偏壓效應(yīng)，隧道埋深大處的塑性區(qū)明顯多于其他區(qū)域。當(dāng)隧道偏壓率分別為1.09、1.13和1.22時(shí)，埋深大處的右邊墻或右拱腰的塑性區(qū)隨著偏壓率增大而增加，，偏壓值為1.22時(shí)，塑性區(qū)范圍達(dá)到最大。 （2）利用模糊層次分析法，對(duì)淺埋偏壓大跨度隧道進(jìn)行了風(fēng)險(xiǎn)評(píng)估研究。在此基礎(chǔ)上，進(jìn)一步確定了淺埋偏壓大跨度隧道8個(gè)風(fēng)險(xiǎn)因素集：偏壓率、地質(zhì)情況、含水狀況、淺埋大小、巖體完整性系數(shù)、巖層產(chǎn)狀、層面與層間裂隙以及圍巖級(jí)別。基于可拓學(xué)的基本物元原理，構(gòu)建了淺埋偏壓大跨度隧道風(fēng)險(xiǎn)的八指標(biāo)可拓風(fēng)險(xiǎn)評(píng)估物元模型，通過(guò)對(duì)定性指標(biāo)的定量化以及歸一化預(yù)處理，使得評(píng)估指標(biāo)具有可比性。 （3）利用克里格算法中不同的變異函數(shù)對(duì)隨機(jī)變量特征進(jìn)行表達(dá)，結(jié)合二次正交組合法，對(duì)隧道襯砌結(jié)構(gòu)的可靠度分析方法進(jìn)行了研究。在計(jì)算過(guò)程中，為克服計(jì)算過(guò)程中隧道力學(xué)參數(shù)的難以確定性，提出了基于超前地質(zhì)預(yù)報(bào)的參數(shù)獲取方法。最后通過(guò)采用克里格法與傳統(tǒng)蒙特卡洛方法的對(duì)比，證明了本文方法的合理性。
[Abstract]:The surrounding rock of shallow buried tunnel is loosely broken, joints and cracks are developed, the surrounding rock is prone to instability and destruction, and some bad disasters, such as roof fall, collapse, water inrush and so on, often occur in the excavation process, and the tunnel bias effect makes the lining structure unbalance in force. It causes the cracking of initial support and secondary lining, reduces the bearing capacity of tunnel structure and destroys the waterproof and drainage system, which may lead to some bad diseases such as water seepage in the operation process. The instability of surrounding rock and lining structure is aggravated by the increase of tunnel excavation width. Therefore, the analysis of surrounding rock stability and construction risk assessment of long span tunnel with shallow-buried bias pressure becomes an urgent problem to be solved. Taking the Yangang tunnel along the Yangtze River as the engineering background, numerical simulation of shallow buried bias tunnel with different net distances is carried out, and the matter element model based on fuzzy analytic hierarchy process and extension theory is used to evaluate the tunnel. The risk assessment of long-span tunnel with shallow buried bias voltage is carried out, and the reliability of surrounding rock stability of long-span tunnel is analyzed by using the Kriging method in geostatistics. The main achievements of this paper are as follows: (1) the mechanical characteristics and failure mode of long span tunnel with shallow bias voltage are studied, and the influence of different factors on tunnel stability is analyzed by FLAC3D software. The results show that the plastic zone in the deep tunnel is more than that in other regions because of the bias effect. When the bias ratio of tunnel is 1.09 ~ 1.13 and 1.22 respectively, the plastic zone of the right wall or right arched waist increases with the increase of bias rate. When the bias voltage is 1.22, the range of plastic zone reaches the maximum. (2) Fuzzy Analytic hierarchy process (AHP) is used. The risk assessment of long span tunnel with shallow bias voltage is studied. On this basis, eight risk factor sets are further determined: bias rate, geological condition, water state, shallow buried size, rock mass integrity coefficient, rock formation, plane and interlayer fracture and surrounding rock level. Based on the matter-element principle of extenics, a matter-element model of eight indexes extension risk assessment for long span tunnel with shallow bias voltage is constructed. The qualitative index is quantified and normalized pretreatment is used. The evaluation indexes are comparable. (3) the reliability analysis method of tunnel lining structure is studied by using different variation functions of Kriging algorithm to express the characteristics of random variables and combining the quadratic orthogonal combination method. In order to overcome the uncertainty of tunnel mechanical parameters in the course of calculation, a parameter acquisition method based on advanced geological prediction is proposed. Finally, the rationality of this method is proved by comparing the Kriging method with the traditional Monte Carlo method.
【學(xué)位授予單位】：湖南科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：U451.2;U455

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本文編號(hào)：2233009