本文關(guān)鍵詞： 天水市 黃土－泥巖滑坡 物理力學(xué)參數(shù) FLAC3D數(shù)值仿真 形成機(jī)理　出處：《長(zhǎng)安大學(xué)》2014年碩士論文　論文類(lèi)型：學(xué)位論文

【摘要】：位于甘肅東南的天水市屬典型河谷城市，受地形地貌、地質(zhì)構(gòu)造、巖土性質(zhì)、降雨等控制和影響，滑坡、崩塌、泥石流等地質(zhì)災(zāi)害發(fā)育且活動(dòng)頻繁，嚴(yán)重威脅著人民生命財(cái)產(chǎn)安全。其中廣泛發(fā)育于天水地區(qū)的黃土-泥巖型滑坡嚴(yán)重影響著當(dāng)?shù)氐墓こ探?jīng)濟(jì)建設(shè)。因此，本文依托國(guó)家自然基金項(xiàng)目“考慮地表水沿裂縫浸入的黃土斜坡穩(wěn)定性研究”，通過(guò)大量區(qū)域調(diào)查，選擇了天水麥積區(qū)職業(yè)技術(shù)學(xué)院南側(cè)斜坡處發(fā)育的一典型黃土－泥巖型滑坡為研究對(duì)象，運(yùn)用現(xiàn)場(chǎng)測(cè)繪、挖探與取樣、室內(nèi)外試驗(yàn)、數(shù)值分析等，研究了該類(lèi)型滑坡形成機(jī)理和運(yùn)動(dòng)過(guò)程，旨在為天水地區(qū)此類(lèi)滑坡穩(wěn)定性預(yù)測(cè)與防治以及國(guó)土規(guī)劃提供理論依據(jù)。 滑坡所在斜坡區(qū)地質(zhì)結(jié)構(gòu)是由第四系黃土層和白堊系泥巖組成，典型的“雙層異質(zhì)”坡體結(jié)構(gòu)特征，斜坡坡度約25°。加之區(qū)域豐富的降雨量，常是此類(lèi)滑坡產(chǎn)生的外在誘發(fā)因素。研究發(fā)現(xiàn)，該滑坡是一中型黃土－泥巖順層滑坡，滑動(dòng)面為黃土泥巖接觸面，滑動(dòng)面受巖層產(chǎn)狀控制，滑面傾角約8。后緣黃土形成的張拉面陡直，呈現(xiàn)出典型蠕動(dòng)－拉裂、滑移－解體和剪斷－擠出的破壞模式。 通過(guò)對(duì)滑坡區(qū)黃土室內(nèi)三軸試驗(yàn)，得出不同含水率下c、的變化規(guī)律，粘聚力c和內(nèi)摩擦角隨著含水率的增大而減小。當(dāng)含水率小于18%時(shí)粘聚力c減小幅度較大，當(dāng)含水率大于18%時(shí)粘聚力c變化幅度較小。同時(shí)，分別研究了相同含水率（20%）與不同圍壓（50kPa、100kPa、150kPa、200kPa、250kPa、300kPa、350kPa、400kPa、450kPa和500kPa），以及相同圍壓（50kPa、100kPa、200kPa、400kPa）與不同含水量（10%、12%、14%、16%、18%、20%、22%和24%）條件下，黃土應(yīng)力應(yīng)變關(guān)系曲線，可以看出隨著含水率的增大，應(yīng)力應(yīng)變曲線逐漸減小，當(dāng)圍壓小于150kPa時(shí)曲線呈弱化型；當(dāng)圍壓大于150kPa時(shí)呈硬化型的結(jié)論。 通過(guò)四組現(xiàn)場(chǎng)原位滲水試驗(yàn)，得出滑體后緣原狀馬蘭黃土滲透系數(shù)為2.26m/d，，經(jīng)過(guò)人工碾壓的滑體土滲透系數(shù)0.23m/d和破碎泥巖的滲透系數(shù)0.91m/d，表明地表水的入滲對(duì)整個(gè)滑坡的產(chǎn)生起到?jīng)Q定性的作用。 現(xiàn)場(chǎng)實(shí)際測(cè)繪了滑坡滑動(dòng)后的工程地質(zhì)平面圖（1:1000）和3條縱斷面圖（1:500），并利用原有滑坡區(qū)地形圖（1:10000）運(yùn)用surfer軟件恢復(fù)了滑坡滑動(dòng)之前斜坡三維斷面圖（1:500）。將滑動(dòng)前后的三維縱斷面通過(guò)CAD-Surfer-Flac3D數(shù)據(jù)文件轉(zhuǎn)換技術(shù)，建立了滑坡數(shù)值仿真的三維計(jì)算模型。 通過(guò)工程地質(zhì)分析，提出了黃土-泥巖型滑坡變形演化機(jī)理表現(xiàn)為三階段，即蠕動(dòng)－拉裂、滑移－解體和剪斷－擠出�；贔lac3D數(shù)值仿真計(jì)算分析了滑坡體的應(yīng)力應(yīng)變特征及滑坡形成機(jī)理，即滑坡前緣向兩邊滑移擴(kuò)散的機(jī)理，并與工程地質(zhì)分析進(jìn)行對(duì)比，結(jié)果基本一致。最后分析了該類(lèi)滑坡運(yùn)動(dòng)機(jī)理，即緩動(dòng)和低速效應(yīng)，表現(xiàn)為滑速低、滑距小等特點(diǎn)。
[Abstract]:Tianshui City, located in southeast Gansu Province, is a typical river valley city, which is controlled and affected by topography, geological structure, rock and soil properties, rainfall and other geological disasters, such as landslide, collapse, debris flow and other geological disasters. It is a serious threat to the safety of people's life and property. The loess-mudstone landslide, which is widely developed in Tianshui area, seriously affects the local engineering and economic construction. This paper relies on the National Natural Fund project "considering the stability of loess slope immersed by surface water along cracks", through a large number of regional investigations. A typical loess-mudstone landslide developed on the southern slope of Tianshui Maiji Vocational and Technical College was selected as the research object. The site mapping, digging and sampling, indoor and outdoor tests, numerical analysis, etc. The formation mechanism and movement process of this type of landslide are studied in order to provide theoretical basis for the stability prediction, prevention and control of this kind of landslide and land planning in Tianshui area. The geological structure of slope area is composed of quaternary loess layer and Cretaceous mudstone, typical "double layer heterogeneous" slope structure characteristics, slope gradient about 25 擄, coupled with abundant rainfall in the region. It is found that the landslide is a middle-sized loess-mudstone bedding landslide, the sliding surface is loess mudstone contact surface, and the sliding surface is controlled by the occurrence of rock strata. The slope angle of the slip surface is about 8. The tensile surface formed by the loess at the rear edge is steeply straight, showing a typical failure mode of creeping and pulling, sliding and disintegrating, and shearing and extruding. Through the laboratory triaxial test of loess in landslide area, the variation law of c, is obtained under different moisture content. The cohesion C and the internal friction angle decrease with the increase of moisture content. When the water content is less than 18, the cohesion C decreases greatly, and the cohesion c changes slightly when the water content is greater than 18. At the same time. The same moisture content and different confining pressures (50 KPA, 100 KPA, 150 KPA, 200 KPA, 250 KPA, 300 KPA, 350 KPA, respectively) were studied. 400kPa450kPa and 500kPaA, and the same confining pressure 50kPa100kPa200kPa200kPa400kPa) with different water content (10%). Under the conditions of 22% and 24%, the stress-strain curve of loess can be seen to decrease with the increase of water content. When the confining pressure is less than 150 KPA, the curve is weakened. When the confining pressure is greater than 150 KPA, the conclusion is that it is sclerosed. Through the in-situ seepage test of four groups, the permeability coefficient of undisturbed Ma Lan loess in the rear edge of sliding body is 2.26 m / d. The permeability coefficient of the landslide is 0.23 m / d and the permeability coefficient of broken mudstone is 0.91m / d, which indicates that the infiltration of surface water plays a decisive role in the whole landslide. The engineering geological plan (1: 1000) and the 3 longitudinal sections (1: 500) after landslide sliding are actually plotted on the spot. Using the original topographic map of landslide area (1: 10000) and using surfer software to restore the slope 3D section map before landslide slide (1: 500). The 3D profile before and after sliding is transformed by CAD-Surfer-Flac3D data file. A three-dimensional model for numerical simulation of landslide is established. Based on the analysis of engineering geology, the deformation and evolution mechanism of loess mudstone landslide is presented as three stages, that is, creeping and pulling fracture. Based on the Flac3D numerical simulation, the stress-strain characteristics of landslide and the mechanism of landslide formation are analyzed, that is, the mechanism of slip diffusion from the front edge to both sides of the landslide. Compared with engineering geological analysis, the results are basically consistent. Finally, the mechanism of landslide movement, that is, slow-moving and low-velocity effects, is analyzed, which is characterized by low sliding speed and small slip distance.
【學(xué)位授予單位】：長(zhǎng)安大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類(lèi)號(hào)】：P642.22;TU444

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