發(fā)布時間：2018-06-23 19:59

  本文選題：石膏巖 + 軟化試驗(yàn)��； 參考：《重慶大學(xué)》2015年碩士論文

【摘要】：重慶梁忠高速禮讓隧道穿越300m長的石膏層,石膏巖遇水易軟化,對隧道施工安全構(gòu)成嚴(yán)重的威脅,針對這一工程病害特點(diǎn),本文對石膏巖進(jìn)行了一系列的軟化試驗(yàn)研究,為解決工程實(shí)際問題建立了相應(yīng)的理論模型及工程應(yīng)用模型。本文主要開展了以下幾個方面的研究工作:①對國內(nèi)外石膏巖及相類似軟巖的研究現(xiàn)狀進(jìn)行分析和總結(jié),擬定本文的主要研究內(nèi)容和技術(shù)路線;對禮讓隧道工程地質(zhì)特征進(jìn)行分析,著重分析了與石膏巖軟化密切相關(guān)的水文地質(zhì)條件。②對禮讓隧道石膏質(zhì)圍巖的力學(xué)性質(zhì)進(jìn)行了試驗(yàn)研究,開展了單軸、三軸試驗(yàn)及剪切試驗(yàn),獲得了石膏巖的單軸抗壓強(qiáng)度、彈性模量、抗剪強(qiáng)度、泊松比等基本力學(xué)參數(shù),其彈性模量和單軸抗壓強(qiáng)度均較低,屬于軟巖的范疇,巖石破壞形式呈脆性破壞。③針對石膏巖開展了一系列的軟化試驗(yàn)及細(xì)觀試驗(yàn),揭示了石膏巖各項(xiàng)力學(xué)參數(shù)隨浸泡時間的演化規(guī)律,并擬合出了相應(yīng)的軟化方程。石膏巖的單軸抗壓強(qiáng)度、抗剪強(qiáng)度、彈性模量均隨浸泡時間呈負(fù)指數(shù)趨勢下降,而石膏巖泊松比在一定條件下隨浸泡時間的增加而增加;在損傷力學(xué)基礎(chǔ)上,推導(dǎo)出了基于時間因素的石膏巖軟化損傷演化方程,揭示了脆性系數(shù)與軟化損傷變量之間的內(nèi)在關(guān)聯(lián),建立了石膏巖在不同淡水浸泡時間下的軟化深度模型。基于壓汞試驗(yàn)數(shù)據(jù)分析,發(fā)現(xiàn)石膏巖的孔隙率隨浸泡時間的增加而增大,相應(yīng)宏觀表現(xiàn)為石膏巖單軸壓縮過程中孔隙壓密階段延長、變形量增加;隨著浸泡時間的增長,石膏巖性質(zhì)發(fā)生改變,逐漸由脆性向延性轉(zhuǎn)變。④通過分析正交軟化試驗(yàn)結(jié)果,揭示了浸泡時間、溫度和SO42-濃度等因素對石膏巖軟化的影響規(guī)律,運(yùn)用層次分析法計(jì)算出了各個因素的影響權(quán)重,結(jié)果表明:浸泡時間和溫度在石膏巖軟化過程中起決定性的作用,浸泡時間和溫度的影響權(quán)值之和大于97%,其中浸泡時間的影響權(quán)值最大,超過80%,溫度次之,而SO42-濃度對石膏巖的軟化影響幾乎為零,可以忽略不計(jì)。⑤在考慮石膏巖軟化特性、獲得彈性模量和泊松比隨浸泡時間的變化規(guī)律的前提下,基于圓形軸對稱隧道平面應(yīng)變彈性解,建立了考慮軟化效應(yīng)的隧道圍巖自穩(wěn)時間評價模型。對模型進(jìn)行了參數(shù)分析,在相同跨度下,自穩(wěn)時間隨隧道埋深的增加而減小,隨完整性系數(shù)的增大而增加,隨著地下水系數(shù)的增大而減小,圍巖彈性模量越大自穩(wěn)時間越長。分析結(jié)果表明,本文給出的考慮軟化效應(yīng)的隧道圍巖自穩(wěn)時間評價模型與實(shí)際情況相符,說明了該模型的科學(xué)性與合理性。并針對模型中關(guān)于地下水分布特征的簡化問題進(jìn)行了討論,推導(dǎo)出考慮地下水分布特征的彈性模量及泊松比的取值公式。基于現(xiàn)場數(shù)據(jù)和軟化試驗(yàn)結(jié)果,使用該模型對禮讓隧道石膏段圍巖自穩(wěn)時間進(jìn)行了評價。
[Abstract]:Through the 300m long gypsum layer of Liangzhong High-speed Liangzhong Tunnel in Chongqing, the gypsum rock is easy to soften when it meets water, which poses a serious threat to the safety of tunnel construction. In view of the characteristics of this engineering disease, a series of softening tests on gypsum rock have been carried out in this paper. In order to solve the practical engineering problems, the corresponding theoretical model and engineering application model are established. This paper mainly carried out the following aspects of research work: 1 to domestic and foreign gypsum rock and similar soft rock research status analysis and summary, draw up the main research content and technical route of this paper; Based on the analysis of the engineering geological characteristics of Licheng tunnel, the hydrogeological conditions .2, which are closely related to the softening of gypsum rock, are analyzed, and the mechanical properties of the gypsum surrounding rock of the Licheng tunnel are studied experimentally and uniaxially. The uniaxial compressive strength, elastic modulus, shear strength and Poisson's ratio of gypsum rock are obtained by triaxial test and shear test. The elastic modulus and uniaxial compressive strength of gypsum rock are lower and belong to the category of soft rock. A series of softening tests and meso tests were carried out on gypsum rock in the form of brittle failure. 3. The evolution of mechanical parameters of gypsum rock with immersion time was revealed, and the corresponding softening equation was fitted. The uniaxial compressive strength, shear strength and elastic modulus of gypsum rock decrease exponentially with immersion time, while Poisson's ratio of gypsum rock increases with the increase of soaking time under certain conditions. The evolution equation of softening damage of gypsum rock based on time factor is derived, and the inherent relation between brittle coefficient and softening damage variable is revealed, and the softening depth model of gypsum rock under different fresh water immersion time is established. Based on the analysis of mercury injection test data, it is found that the porosity of gypsum rock increases with the increase of soaking time, and the corresponding macroscopic behavior is that the pore compaction stage is prolonged and the deformation amount increases during uniaxial compression of gypsum rock, and with the increase of soaking time, the porosity of gypsum rock increases with the increase of immersion time. The properties of gypsum rock change gradually from brittleness to ductility. By analyzing the results of orthogonal softening test, the effects of soaking time, temperature and so _ 42- concentration on the softening of gypsum rock are revealed. The influence weight of each factor is calculated by AHP. The results show that the soaking time and temperature play a decisive role in the softening process of gypsum rock. The sum of the influence weights of soaking time and temperature is greater than 97, in which the influence weight of soaking time exceeds 80, followed by temperature, and the effect of so _ 42- concentration on the softening of gypsum rock is almost zero, which can be ignored when considering the softening characteristics of gypsum rock. Based on the elastic modulus and Poisson's ratio changing with immersion time and based on the plane strain elastic solution of circular axisymmetric tunnel, a self-stability time evaluation model of tunnel surrounding rock considering softening effect is established. Under the same span, the self-stability time decreases with the increase of the tunnel depth, increases with the increase of the integrity coefficient, decreases with the increase of the groundwater coefficient, and increases with the increase of the elastic modulus of surrounding rock. The analysis results show that the evaluation model of self-stability time of tunnel surrounding rock considering softening effect is consistent with the actual situation, which shows that the model is scientific and reasonable. The simplified problem of groundwater distribution characteristics in the model is discussed, and the formula of elastic modulus and Poisson's ratio considering the characteristics of groundwater distribution is derived. Based on field data and softening test results, the self-stability time of surrounding rock in gypsum section of Licheng tunnel is evaluated by using the model.
【學(xué)位授予單位】：重慶大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：U451.2

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本文編號：2058225