本文關(guān)鍵詞：滲流和地震耦合作用下邊坡穩(wěn)定性分析　出處：《中國(guó)地震局工程力學(xué)研究所》2017年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 滲流 地震 極限平衡法 數(shù)值模擬 邊坡穩(wěn)定性

【摘要】：地下水滲流和地震對(duì)邊坡的穩(wěn)定性都有重要影響,滲流和地震共同作用這一復(fù)雜工況下的邊坡穩(wěn)定性問題已成為當(dāng)前巖土工程研究的熱點(diǎn)問題之一。主要問題是滲流和地震共同作用時(shí)穩(wěn)定性的計(jì)算方法需要探索和完善;各種影響因素需要深入分析和研究。本文的研究工作為解決復(fù)雜工況下的邊坡穩(wěn)定性分析和評(píng)價(jià)提供了一種新的思路,這一工作對(duì)多工況耦合作用下的邊坡失穩(wěn)機(jī)理研究和穩(wěn)定性評(píng)價(jià)具有重要的理論參考和實(shí)際意義。本文在前人已有工作的基礎(chǔ)上,基于極限平衡理論和數(shù)值模擬開展了滲流和地震兩種工況耦合作用下的邊坡穩(wěn)定性分析和計(jì)算方法的研究;并對(duì)特殊類邊坡的穩(wěn)定性問題進(jìn)行了分析和探討,主要工作和成果如下:1、推導(dǎo)并給出了砂土邊坡和粘土邊坡在滲流和地震作用下安全系數(shù)的解析式;提出了水平積分模型的廣義形式。相關(guān)算例結(jié)果對(duì)比表明,依賴嚴(yán)格幾何條件和邊界約束的解析法可以得到其它方法一致的結(jié)論,計(jì)算結(jié)果反映了安全系數(shù)隨振動(dòng)時(shí)間的變化規(guī)律,計(jì)算值要小于規(guī)范中的擬靜力法結(jié)果,但與動(dòng)力時(shí)程法結(jié)果基本相近,具有一定的可靠性。參數(shù)分析表明水力梯度和水位差對(duì)邊坡穩(wěn)定性的影響顯著,特別是高水位差時(shí)邊坡穩(wěn)定性顯著降低,水平方向地震力會(huì)嚴(yán)重削弱邊坡的穩(wěn)定程度,而豎向地震力對(duì)穩(wěn)定性的影響要小于水平地震力的作用。本文通過數(shù)學(xué)積分得到了異形邊坡水平積分模型的解析算式,結(jié)果表明,該方法計(jì)算的安全系數(shù)一般偏低,穩(wěn)定性評(píng)價(jià)相對(duì)保守。采用解析方法得到的邊坡安全系數(shù)對(duì)深入開展?jié)B流和地震耦合作用下的邊坡失穩(wěn)機(jī)理的研究提供了重要理論基礎(chǔ),為進(jìn)一步探索安全系數(shù)變化規(guī)律提供了有效工具。2、提出了以滑動(dòng)面傾角為權(quán)重的整體安全系數(shù)評(píng)價(jià)方法,并以天津波作為輸入地震動(dòng),結(jié)合點(diǎn)安全系數(shù)法分析了滲流和地震復(fù)雜工況下的邊坡穩(wěn)定性。本文取實(shí)際工程中的兩臺(tái)階邊坡為研究對(duì)象,討論了滲流應(yīng)力耦合作用對(duì)兩臺(tái)階邊坡應(yīng)力場(chǎng)、位移場(chǎng)的影響以及平臺(tái)寬度、邊坡傾角等坡體參數(shù)對(duì)穩(wěn)定性的影響。研究結(jié)果表明,修正后的整體安全系數(shù)要比傳統(tǒng)的瑞典條分法給出的結(jié)果偏高,與有限元強(qiáng)度折減法所得的結(jié)果和前期勘察結(jié)論基本一致。滲流應(yīng)力耦合作用對(duì)邊坡的水平位移影響明顯,對(duì)豎向位移影響較小,對(duì)具有強(qiáng)滲透性的砂土類邊坡應(yīng)重點(diǎn)考察耦合作用對(duì)應(yīng)力場(chǎng)和位移場(chǎng)的影響,而平臺(tái)寬度和邊坡傾角是制約滑動(dòng)面形狀和位置的重要因素,同時(shí)說明了多階邊坡的剪出口不再唯一。本文的工作提示,應(yīng)用點(diǎn)安全系數(shù)法分析邊坡穩(wěn)定性時(shí),應(yīng)盡量采用高階單元、低網(wǎng)格劃分、大尺度邊界的計(jì)算原則,這樣可以提高計(jì)算效率,降低計(jì)算成本。3、提出了坡頂裂縫最大取值的界定依據(jù),分析了復(fù)雜工況下裂縫尖端的應(yīng)力強(qiáng)度因子。本文研究結(jié)果表明,基于單軸最大拉應(yīng)力理論和土體變形參數(shù)所得到的裂縫深度計(jì)算公式,可約束坡頂最大裂縫的取值。與極限平衡法相結(jié)合,可計(jì)算張拉剪切作用下的邊坡安全系數(shù),所得結(jié)果是安全系數(shù)的下限值,穩(wěn)定性評(píng)價(jià)偏于保守。本文利用應(yīng)力強(qiáng)度因子較好地解釋了坡頂裂縫在側(cè)向水壓力和水平地震力作用下裂縫擴(kuò)展的原因,并與數(shù)值模擬中裂縫尖端位置的應(yīng)力集中基本一致。盡管本文的相關(guān)方法為拉剪復(fù)合破壞模式下的邊坡穩(wěn)定性分析提供了一種新思路,但方法的可靠性還需進(jìn)一步檢驗(yàn)。4、推導(dǎo)了軟弱夾層自振頻率的近似解,提出了含軟弱夾層這類特殊邊坡穩(wěn)定性的簡(jiǎn)化計(jì)算方法及適用范圍。研究結(jié)果表明,含軟弱夾層邊坡的失穩(wěn)是由坡體與夾層的共同作用所導(dǎo)致。本文利用彈性力學(xué)中的能量法計(jì)算了軟弱夾層的自振頻率,通過與諧波共振結(jié)果對(duì)比,說明了軟弱夾層在邊坡失穩(wěn)中的重要作用。基于極限平衡理論,以圓弧滑動(dòng)占復(fù)合滑動(dòng)的比值為權(quán)重,本文給出了含軟弱夾層邊坡穩(wěn)定性的簡(jiǎn)化計(jì)算方法。相關(guān)算例結(jié)果對(duì)比表明,簡(jiǎn)化方法計(jì)算的安全系數(shù)一般偏小,并對(duì)軟弱夾層厚度小、傾角小、水平分布在坡底的這一類邊坡較為適用;對(duì)于夾層厚度較大的邊坡,建議簡(jiǎn)化為本文中的成層土邊坡進(jìn)行分析。
[Abstract]:Have an important impact on the stability of groundwater seepage and earthquake on slope, the slope stability problem of the complicated interaction of seepage and earthquake has become one of the hot issues in the research of geotechnical engineering. The main problem is the interaction of seepage and earthquake stability calculation method to explore and perfect the in-depth analysis and study of factors; a variety of effects. The research work provides a new way to solve the slope stability analysis and evaluation of complex conditions, with theoretical reference and practical significance of this research and evaluation mechanism of losing stability on the slope stability condition under coupling. Based on the previous work, the research limit equilibrium theory and numerical simulation to carry out stability analysis of slope seepage and earthquake two conditions under the coupling effect and calculation method based on and on; Analyzed and discussed the stability problem of slope is the main work and results are as follows: 1. The analytic formula and safety coefficient are given in the sand slope and clay slope seepage and earthquake; proposed a generalized form integral level model. The numerical results show that the correlation ratio, analytic method relies on strict geometric conditions and boundary constraints can come to the conclusion that other methods consistent with the calculation results reflect the variation of safety coefficient with the vibration time, the calculated values to be pseudo static method result is less than the norm, but with the dynamic time history analysis results, has certain reliability. Parameter analysis shows that the hydraulic gradient and the water level difference effect on slope stability obviously, especially the high water level difference of slope stability decreased significantly, the horizontal seismic force will seriously undermine the stability of the slope, and the vertical seismic force on the stability. Ring is smaller than the horizontal seismic force. Through mathematical integral formula, special slope level integration model. The results show that the safety factor calculated by this method is generally low, the stability evaluation is relatively conservative. Provide the important theoretical basis of the study of slope safety coefficient obtained by the analytical method to carry out the slope seepage and earthquake the mechanism of instability, provides an effective tool for further exploration of.2 variation of safety factor, put forward the overall safety factor evaluation method of weight to the sliding surface inclination, and taking Tianjin wave as the input ground motion, seepage and earthquake under the complicated conditions of slope stability analysis with the point safety factor method. Two steps slope this paper takes the actual project as research object, discusses the seepage stress coupling stress of two steps slope field, displacement field and flat effect Table width, slope angle and slope parameters influence on the stability. The results show that the safety factor of the modified than traditional Fellenius method gives higher results, the conclusion and the strength reduction FEM results and preliminary investigation should be basically the same. The seepage influence on the horizontal displacement of slope stress. Obviously, has little effect on the vertical displacement, the strong permeability of sandy soil slope should investigate the coupling effects of stress field and displacement field, and the width of the platform and the slope angle is an important factor restricting the shape and position of the sliding surface, and indicates that the shear outlet of multi-step slope is no longer the only. This work suggests that the slope stability analysis, application of point safety factor method, should be used in high order element, low meshing, calculation principle of large scale boundary, so it can improve the computational efficiency, lower calculation The.3, put forward the definition according to the maximum value of slope crack, analyzes the stress intensity factors of crack under complicated working conditions. The results of this study indicate that the crack depth formula of uniaxial tensile theory and soil deformation parameters obtained based on the slope can constrain fracture combined with limit values. Balance method, can calculate the tension of slope safety factor under shear, the result is the lower limit of safety coefficient, stability evaluation on the conservative side. The stress intensity factor can explain the cause of crack in the lateral water pressure and horizontal seismic force of slope cracks, and is consistent with the stress concentration the crack tip position in numerical simulation. Although this method provides a new idea for slope stability analysis of composite shear failure modes, but the reliability of the method also need one Step.4 inspection is the approximate solution of weak interlayer vibration frequency, calculation method is put forward and the scope of this special kind of slope with weak interlayer stability is simplified. The results show that the slope with weak interlayer instability is caused by a combination of slope and interlayer. In this paper, the natural frequency of weak interlayer is calculated by using the energy method in elastic mechanics, by comparing with the harmonic resonance results shows that weak layers in the slope stability in an important role. Based on the theory of limit equilibrium, the circular sliding ratio of composite sliding as the weights are given in this paper with the simplified calculation method of slope stability of weak interlayer. Numerical results show that the contrast the safety coefficient is generally small, simplified calculating method, and the soft interlayer thickness is small, a small angle, the horizontal distribution is more applicable in this kind of slope slope; slope for large thickness, It is suggested to simplify the analysis of the layered soil slope in this paper.

【學(xué)位授予單位】：中國(guó)地震局工程力學(xué)研究所
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：TU43

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