【摘要】：軟巖具有比硬巖更加復(fù)雜的力學(xué)特性,其作為工程巖體時(shí)往往表現(xiàn)出應(yīng)變軟化、流變及非線性大變形等工程力學(xué)特性,是影響工程長(zhǎng)期穩(wěn)定性的關(guān)鍵因素,因此,深入開(kāi)展軟巖力學(xué)特性方面的研究具有重要意義。本文選取軟巖隧洞砂質(zhì)泥巖為研究對(duì)象,通過(guò)室內(nèi)試驗(yàn)對(duì)其力學(xué)特性進(jìn)行了研究,主要的研究?jī)?nèi)容如下： 1)采用RMT-150C巖石力學(xué)試驗(yàn)系統(tǒng)進(jìn)行砂質(zhì)泥巖三軸壓縮及卸荷試驗(yàn),研究了不同應(yīng)力路徑下巖石的強(qiáng)度、變形以及破壞特征,獲得了壓縮及卸荷應(yīng)力路徑下巖石的基本力學(xué)參數(shù)。 2)針對(duì)三軸壓縮及卸荷試驗(yàn)中無(wú)法根據(jù)應(yīng)力-應(yīng)變曲線直接確定砂質(zhì)泥巖試樣峰值強(qiáng)度這一問(wèn)題,將半對(duì)數(shù)法引入到試驗(yàn)數(shù)據(jù)分析中,利用1g(σ1-σ3)～ε,關(guān)系曲線和σ3～1gε1關(guān)系曲線較方便的確定了巖樣的峰值強(qiáng)度值,并基于應(yīng)力增量、應(yīng)變?cè)隽颗c應(yīng)力之間的關(guān)系曲線|△ε1/△(σ1-σ3)|～(σ1-σ3)對(duì)取值方法的合理性進(jìn)行了驗(yàn)證。 3)采用RLW-2000微機(jī)控制巖石三軸蠕變?cè)囼?yàn)機(jī)對(duì)砂質(zhì)泥巖進(jìn)行恒軸壓卸圍壓和加軸壓卸圍壓應(yīng)力路徑下的分級(jí)卸荷流變?cè)囼?yàn),對(duì)比分析了兩種應(yīng)力路徑下砂質(zhì)泥巖試樣軸向及側(cè)向變形隨時(shí)間的變化規(guī)律;探討了兩種應(yīng)力路徑下加速流變階段砂質(zhì)泥巖試樣流變變形特征和速率發(fā)展規(guī)律;利用等時(shí)曲線法確定了不同卸荷初始圍壓下砂質(zhì)泥巖試樣的長(zhǎng)期強(qiáng)度,并引入強(qiáng)度比概念對(duì)比分析兩種應(yīng)力路徑下長(zhǎng)期強(qiáng)度與破壞應(yīng)力間的比例關(guān)系;分析了不同應(yīng)力路徑下砂質(zhì)泥巖試樣的破壞特征及其隨卸荷初始圍壓變化的發(fā)展規(guī)律。 4)基于卸荷流變?cè)囼?yàn)全過(guò)程曲線,采用西原模型對(duì)應(yīng)力水平小于σs(巖石流變破壞的前一級(jí)應(yīng)力水平)條件下砂質(zhì)泥巖的流變特征進(jìn)行了描述,利用Levenb erg-Marquardt優(yōu)化算法對(duì)模型中各流變參數(shù)進(jìn)行了優(yōu)化辨識(shí)。 5)以西原模型為基礎(chǔ),引入非線性黏塑性流變?cè)⒘艘粋�(gè)新的非線性黏彈塑性流變模型,使其能夠較好的描述破壞圍壓下砂質(zhì)泥巖流變?nèi)^(guò)程曲線的非線性加速流變階段,驗(yàn)證分析表明該模型計(jì)算的應(yīng)力-應(yīng)變曲線與試驗(yàn)曲線比較吻合,表明所建立的非線性黏彈塑性流變模型是合理的。 6)對(duì)新建立的非線性黏彈塑性流變本構(gòu)模型在FLAC3D程序中予以數(shù)值實(shí)現(xiàn)并將其運(yùn)用于某水電站引水隧洞的長(zhǎng)期穩(wěn)定性計(jì)算分析,研究成果可為隧洞圍巖的長(zhǎng)期穩(wěn)定性研究和隧洞長(zhǎng)期運(yùn)行的安全性分析提供一定的參考價(jià)值。
[Abstract]:Soft rock has more complex mechanical properties than hard rock. As engineering rock mass, soft rock often shows such engineering mechanical properties as strain softening, rheology and nonlinear large deformation, which are the key factors that affect the long-term stability of engineering. It is of great significance to further study the mechanical properties of soft rock. In this paper, sand mudstone of soft rock tunnel is chosen as the research object, and its mechanical properties are studied through laboratory tests. The main research contents are as follows: 1) the RMT-150C rock mechanics test system is used to test the triaxial compression and unloading of sandy mudstone, and the strength, deformation and failure characteristics of the rock under different stress paths are studied. The basic mechanical parameters of rock under compression and unloading stress paths are obtained. 2) in order to solve the problem that the peak strength of sandy mudstone specimen can not be determined directly by stress-strain curve in triaxial compression and unloading test, the semi-logarithmic method is introduced into the analysis of test data, and 1g (蟽 1- 蟽 3) 蔚 is used. The peak strength of rock samples is easily determined by the relationship curve and 蟽 3 + 1g 蔚 1 curve, and based on the stress increment, The relationship between strain increment and stress is verified by the curve of 蔚 _ 1 / (蟽 _ 1- 蟽 _ 3) ~ (蟽 _ 1- 蟽 _ 3) ~ (蟽 _ 1- 蟽 _ 3). 3) RLW-2000 microcomputer controlled triaxial creep testing machine is used to test sand mudstone under constant axial pressure unloading confining pressure and axial compression unloading confining pressure path. The variation of axial and lateral deformation of sandy mudstone samples with time under two stress paths is comparatively analyzed. The rheological deformation characteristics and rate development of sandy mudstone samples at accelerated rheological stage under two stress paths are discussed. The long-term strength of sandy mudstone samples under different initial confining pressures is determined by isochronous curve method, and the relationship between long-term strength and failure stress under two stress paths is analyzed by introducing the concept of strength ratio. The failure characteristics of sandy mudstone samples under different stress paths and the development law of the change of initial confining pressure with unloading are analyzed. 4) based on the whole process curve of unloading rheological test, the rheological characteristics of sandy mudstone with stress level less than 蟽 s (the first stress level of rock rheological failure) are described by using the Xiyuan model. The rheological parameters of the model are identified by Levenb erg-Marquardt optimization algorithm. 5) based on the original model, a new nonlinear viscoelastic-plastic rheological model is established by introducing nonlinear viscoplastic rheological elements. It can describe the nonlinear accelerated rheological phase of the whole rheological process curve of sandy mudstone under the failure confining pressure. The verification and analysis show that the stress-strain curve calculated by this model is in good agreement with the experimental curve. It is shown that the nonlinear viscoelastic-plastic rheological model is reasonable. 6) the new nonlinear viscoelastic-plastic constitutive model is numerically realized in FLAC3D program and applied to the long-term stability analysis of the diversion tunnel of a hydropower station. The results can provide some reference value for the study of the long-term stability of the surrounding rock and the safety analysis of the tunnel in the long run.
【學(xué)位授予單位】：三峽大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類(lèi)號(hào)】：TU45

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