【摘要】：非飽和土問(wèn)題得到越來(lái)越多的關(guān)注,其中處于非飽和狀態(tài)下的邊坡安全問(wèn)題是亟待解決的問(wèn)題。非飽和土邊坡失穩(wěn)不僅對(duì)人身財(cái)產(chǎn)造成巨大損失同時(shí)也對(duì)人類的安全造成嚴(yán)重的危害。降雨等原因會(huì)引起土體含水量的改變進(jìn)而導(dǎo)致邊坡土體的抗剪強(qiáng)度的改變,影響到邊坡的穩(wěn)定狀態(tài)。研究非飽和-飽和狀態(tài)變化對(duì)邊坡穩(wěn)定性的影響具有重要的工程意義。非飽和土中含水率、粘聚力、基質(zhì)吸力和內(nèi)摩擦角是相互關(guān)聯(lián)的重要物理力學(xué)參數(shù)。非飽和土內(nèi)部賦存的基質(zhì)吸力是其不同于飽和土的本質(zhì)原因,當(dāng)含水量發(fā)生變化時(shí),非飽和土的基質(zhì)吸力相應(yīng)變化,不同深度的基質(zhì)吸力分布情況也隨著改變;作為非飽和狀態(tài)下土體抗剪強(qiáng)度的重要組成部分,基質(zhì)吸力的改變直接影響著土體結(jié)構(gòu)的抗剪強(qiáng)度,決定著土質(zhì)邊坡的穩(wěn)定性。根據(jù)土骨架應(yīng)力狀態(tài)下飽和土與非飽和土抗剪強(qiáng)度的統(tǒng)一公式,結(jié)合基質(zhì)吸力與土-水特征曲線(SWCC),對(duì)非飽和土體的抗剪強(qiáng)度公式進(jìn)行變換,獲得能夠反映土體非飽和-飽和狀態(tài)變化與抗剪強(qiáng)度相關(guān)聯(lián)的參數(shù)—等效粘聚力。依據(jù)非飽和-飽和狀態(tài)變化條件下,土體含水量、基質(zhì)吸力分布不同,編制計(jì)算程序?qū)吰逻M(jìn)行等效粘聚力的賦值,進(jìn)行初始平衡、流體平衡、等效粘聚力重新分布和安全系數(shù)計(jì)算,分析非飽和-飽和狀態(tài)變化下土質(zhì)邊坡的穩(wěn)定性。通過(guò)模擬不同入滲深度條件下邊坡數(shù)值計(jì)算,對(duì)不同土層孔隙水壓力、基質(zhì)吸力分布、剪應(yīng)變?cè)隽吭茍D和安全系數(shù)等數(shù)據(jù)分析,研究入滲導(dǎo)致的土體從非飽和狀態(tài)到飽和狀態(tài)變化過(guò)程中邊坡的穩(wěn)定性變化規(guī)律,分析邊坡土體狀態(tài)變化過(guò)程中,等效粘聚力的變化對(duì)于邊坡安全系數(shù)的影響以及邊坡滑移面的變化情況�；跀�(shù)值計(jì)算結(jié)果,得到非飽和-飽和狀態(tài)變化條件下,土質(zhì)邊坡穩(wěn)定性變化規(guī)律與分析含水量、基質(zhì)吸力、等效粘聚力之間的內(nèi)在聯(lián)系;進(jìn)一步獲得土體由非飽和狀態(tài)向飽和狀態(tài)轉(zhuǎn)變過(guò)程中邊坡安全系數(shù)的變化規(guī)律,為實(shí)際工程背景下的邊坡失穩(wěn)災(zāi)害防治和優(yōu)化設(shè)計(jì)與施工方案提供理論指導(dǎo)和技術(shù)支持。
[Abstract]:More and more attention has been paid to the problem of unsaturated soil, in which slope safety in unsaturated state is an urgent problem to be solved. The instability of unsaturated soil slope not only causes huge loss of life and property, but also causes serious harm to human safety. Rainfall and other reasons will cause the change of soil moisture content and the shear strength of the slope, which will affect the stability of the slope. It is of great engineering significance to study the influence of unsaturated-saturated state on slope stability. Moisture content, cohesion, matrix suction and internal friction angle are important physical and mechanical parameters related to each other in unsaturated soil. The internal matrix suction of unsaturated soil is the essential reason which is different from saturated soil. When the water content changes, the matrix suction of unsaturated soil changes correspondingly, and the distribution of matrix suction in different depth also changes with the change of water content. As an important part of soil shear strength in unsaturated state, the change of matrix suction directly affects the shear strength of soil structure and determines the stability of soil slope. According to the unified formula of shear strength of saturated soil and unsaturated soil under the state of soil skeleton stress, combined with matrix suction and soil-water characteristic curve (SWCC), the formula of shear strength of unsaturated soil is transformed. The equivalent cohesive force, which can reflect the variation of unsaturated-saturated state and shear strength of soil, is obtained. According to the different distribution of soil water content and matrix suction under the condition of unsaturated and saturated state, the calculation program is compiled to assign the equivalent cohesive force to the slope, to carry out the initial equilibrium and the fluid balance. The stability of soil slope under unsaturated-saturated state is analyzed by redistribution of equivalent cohesive force and calculation of safety factor. By simulating the slope numerical calculation under different infiltration depth, the data of pore water pressure, matrix suction distribution, shear strain increment cloud diagram and safety factor of different soil layers are analyzed. The variation law of slope stability caused by infiltration from unsaturated state to saturated state is studied, and the process of slope soil state change is analyzed. The influence of the equivalent cohesive force on the slope safety factor and the variation of slope slip surface. Based on the numerical results, the internal relations between the stability of soil slope and the analysis of water content, matrix suction and equivalent cohesive force are obtained under the condition of unsaturated and saturated state. Furthermore, the variation law of slope safety factor in the process of changing from unsaturated state to saturated state is obtained, which provides theoretical guidance and technical support for slope instability disaster prevention and optimization design and construction scheme under the background of practical engineering.
【學(xué)位授予單位】：燕山大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TU43

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