本文關(guān)鍵詞： 持續(xù)降雨 非飽和黏土邊坡 入滲方式 失穩(wěn)機(jī)理 模型試驗(yàn)　出處：《蘭州大學(xué)》2014年博士論文　論文類型：學(xué)位論文

【摘要】：降雨入滲是天然邊坡和工程邊坡失穩(wěn)的重要誘因,多雨地區(qū)的黏土邊坡因持續(xù)降雨誘發(fā)的滑坡災(zāi)害十分嚴(yán)重。降雨滲入原本穩(wěn)定的黏土邊坡,加速了邊坡變形破壞。因此,進(jìn)行持續(xù)降雨入滲黏土邊坡的入滲規(guī)律分析和失穩(wěn)機(jī)理研究對(duì)多雨地區(qū)邊坡滑坡災(zāi)害防治具有重要的意義。本文將非飽和-飽和土邊坡極限平衡理論和土壤水滲流理論相互融合,運(yùn)用強(qiáng)度折減數(shù)值計(jì)算方法,并結(jié)合模擬試驗(yàn)和工程實(shí)際進(jìn)行分析,主要進(jìn)行了以下幾方面的研究： 首先,本文結(jié)合降雨誘發(fā)工程邊坡破壞的現(xiàn)狀,探討了雨水入滲作用下的邊坡黏土工程特性和邊坡穩(wěn)定機(jī)理。將不同含水量的黏土進(jìn)行室內(nèi)試驗(yàn),獲得了不同含水量黏土的抗剪強(qiáng)度及相關(guān)參數(shù),并通過(guò)基質(zhì)吸力試驗(yàn)數(shù)據(jù)擬合發(fā)現(xiàn)該黏土SWCC曲線指數(shù)擬合式更合理。 接著,探討了持續(xù)降雨條件下坡面雨水入滲深度以及入滲方式。結(jié)合黏土飽和入滲原理和Green-Ampt入滲方式,考慮坡內(nèi)黏土初始含水量相同和有規(guī)律變化兩種情況,分別計(jì)算雨水飽和入滲與非飽和入滲下坡面積水時(shí)間、積水時(shí)的入滲深度和入滲率。 進(jìn)而,利用極限平衡理論和有限差分強(qiáng)度折減法,考慮非飽和黏土基質(zhì)吸力和滲流力,建立了持續(xù)降雨入滲非飽和黏土邊坡極限平衡條分法的計(jì)算式、強(qiáng)度折減法的計(jì)算式。研究了持續(xù)降雨過(guò)程引起的含水量和容重增加、粘聚力和內(nèi)摩擦角減小,從而誘發(fā)土坡的安全系數(shù)快速下降。綜合分析了黏土邊坡穩(wěn)定性的影響因素,建立了黏土物理力學(xué)參數(shù)對(duì)邊坡穩(wěn)定性影響的理論計(jì)算式。通過(guò)數(shù)值方法計(jì)算各參數(shù)影響下的安全系數(shù)和最大水平位移,得到黏土含水量、粘聚力、內(nèi)摩擦角、基質(zhì)吸力、邊坡高度和坡角等參數(shù)的靈敏度,從而確定了非飽和黏土邊坡重要物理力學(xué)參數(shù)的靈敏程度順序。通過(guò)各種黏土屈服準(zhǔn)則參數(shù)的相互變換,可得到持續(xù)降雨工況下的黏土內(nèi)摩擦角φ=16.5°可作為其屈服準(zhǔn)則選取或調(diào)整的臨界點(diǎn)。 然后,通過(guò)邊坡模擬試驗(yàn)直觀展現(xiàn)了模型邊坡在持續(xù)降雨工況下的變形破壞過(guò)程,驗(yàn)證了持續(xù)降雨入滲過(guò)程存在非飽和入滲方式。獲得了持續(xù)降雨過(guò)程中坡頂、坡中和坡腳三個(gè)位置不同深度處黏土基質(zhì)吸力,并分別以坡頂或坡中入滲深度和坡腳點(diǎn)確定的潛在滑面進(jìn)行模型邊坡的穩(wěn)定性計(jì)算,得到了以坡中位置入滲深度15cm左右的潛在滑面安全系數(shù)最小。 最后,結(jié)合工程實(shí)際,探討了持續(xù)降雨條件下邊坡平臺(tái)、坡高和坡率的設(shè)置效果。系統(tǒng)研究了雨水不同入滲深度時(shí)的邊坡安全系數(shù)和邊坡可能的失穩(wěn)時(shí)間,并分析了持續(xù)降雨入滲條件下工程邊坡的穩(wěn)定性。
[Abstract]:Rainfall infiltration is an important cause of instability of natural slope and engineering slope. The landslide disaster induced by continuous rainfall is very serious in the clay slope in rainy area. Rainfall infiltrates into the originally stable clay slope. Accelerate the slope deformation and damage. It is of great significance to study the infiltration law and instability mechanism of continuous rainfall infiltration clay slope for slope landslide disaster prevention in rainy area. In this paper, the limit equilibrium theory of unsaturated saturated soil slope and soil water infiltration are introduced. The flow theory merges with each other. Using the numerical calculation method of strength reduction, combined with the simulation test and engineering practice, the following aspects of the research are mainly carried out: Firstly, combined with the current situation of slope failure induced by rainfall, the engineering characteristics of slope clay and slope stability mechanism under the action of Rain Water infiltration are discussed. The clay with different water content is tested in laboratory. The shear strength and related parameters of clay with different moisture content were obtained, and the fitting formula of SWCC curve index was found to be more reasonable by fitting the matrix suction test data. Then, the paper discusses the infiltration depth and infiltration mode of Rain Water on slope under the condition of continuous rainfall, combined with the saturated infiltration principle of clay and Green-Ampt infiltration mode. Considering the same initial water content and regular variation of the clay in the slope, the water time of the slope area under the Rain Water saturated infiltration and the unsaturated infiltration, the infiltration depth and the infiltration rate are calculated respectively. Then, by using the limit equilibrium theory and the finite difference strength reduction method, considering the suction and seepage force of unsaturated clay matrix, the calculation formula of limit equilibrium strip method for unsaturated clay slope with continuous rainfall infiltration is established. The calculation formula of strength reduction method. The increase of water content and bulk density caused by continuous rainfall, the decrease of cohesion and internal friction angle are studied. Therefore, the safety factor of soil slope decreases rapidly, and the factors influencing the stability of clay slope are comprehensively analyzed. A theoretical formula for calculating the influence of physical and mechanical parameters of clay on slope stability is established. The safety factor and maximum horizontal displacement under the influence of each parameter are calculated by numerical method, and the water content, cohesive force and internal friction angle of clay are obtained. The sensitivity order of important physical and mechanical parameters of unsaturated clay slope is determined by the sensitivity of matrix suction, slope height and slope angle. The critical point of selecting or adjusting the yield criterion can be obtained that the angle of internal friction of clay is 16.5 擄under the condition of continuous rainfall. Then, the deformation and failure process of the model slope under the condition of continuous rainfall is demonstrated intuitively through the slope simulation test. The unsaturated infiltration mode was verified in the process of continuous rainfall infiltration, and the clay matrix suction at three different depths of slope top, slope and foot of slope was obtained during the process of continuous rainfall. The stability of the model slope is calculated with the potential slip surface determined by the infiltration depth of the top or middle slope and the slope foot point, and the minimum safety factor of the potential slip surface with the infiltration depth of 15 cm in the middle position of the slope is obtained. Finally, combined with engineering practice, the setting effect of slope platform, slope height and slope rate under the condition of continuous rainfall is discussed, and the slope safety factor and the possible instability time of slope under different infiltration depth of Rain Water are systematically studied. The stability of engineering slope under the condition of continuous rainfall infiltration is analyzed.
【學(xué)位授予單位】：蘭州大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：TU43

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