發(fā)布時間：2018-06-19 03:05

  本文選題：降雨 + 庫水位下降　； 參考：《成都理工大學(xué)》2015年碩士論文

【摘要】：李家灣滑坡位于重慶市長壽區(qū)鳳城鎮(zhèn)三洞村桃花溪右岸斜坡一帶,區(qū)內(nèi)降雨豐富,且降雨量大,受庫水位漲落和降雨的影響,研究區(qū)的變形有進(jìn)一步發(fā)展的趨勢,考慮到研究區(qū)內(nèi)分布有大量民房,居住有居民和企業(yè)職工共368人,且長壽區(qū)供水管道在此通過,該供水管道承擔(dān)了長壽區(qū)大于5萬戶居民的日常生活用水任務(wù),若滑坡復(fù)活失穩(wěn),將直接威脅到居民和企業(yè)職工的生命財產(chǎn)安全,影響長壽區(qū)居民正常的日常生活,因此研究老滑坡的復(fù)活機制并對其穩(wěn)定性進(jìn)行評價具有重要的現(xiàn)實意義。本文通過對李家灣滑坡的地質(zhì)結(jié)構(gòu)、水文地質(zhì)特征,滑坡強-弱變形區(qū)的發(fā)育特征的分析,揭露滑坡的復(fù)活機制及影響因素;運用Geo-studio軟件對滑坡的主變形區(qū)進(jìn)行滲流場的數(shù)值模擬,得到不同工況下的浸潤線變化、孔隙水壓力等值線圖,評價其對滑坡穩(wěn)定性的影響,在此基礎(chǔ)上,采用灰色關(guān)聯(lián)度理論研究不同抗剪強度指標(biāo)、降雨量大小及不同庫水位高程對滑坡穩(wěn)定性的敏感強度,最后采用FLAC3D數(shù)值模擬對主變形區(qū)的應(yīng)力、應(yīng)變場、塑性區(qū)進(jìn)行分析研究,取得了如下主要成果。(1)李家灣滑坡是在滑坡的內(nèi)在和外在條件的作用下發(fā)生的,其中內(nèi)部條件包括地形地貌、地質(zhì)構(gòu)造、坡體結(jié)構(gòu)特征,外在條件主要為降雨和河流下切。其中砂泥巖軟硬互層的坡體結(jié)構(gòu)特征,坡體易沿平緩的軟弱夾層向坡前臨空方向產(chǎn)生壓致拉裂,在暴雨條件下,坡體在靜水壓力和空隙水揚壓力的聯(lián)合作用下發(fā)生滑動。(2)李家灣滑坡的復(fù)活區(qū)分為3個強變形區(qū),1個弱變形區(qū)。李家灣滑坡的復(fù)活由庫水位的變動和降雨引起,其中降雨是滑坡復(fù)活的主要誘發(fā)因素,其對滑坡的影響主要表現(xiàn)在:雨水入滲降低土體的抗剪強度,增加坡體的自重,從而增大坡體的下滑力。從非飽和土力學(xué)原理,雨水滲入滑坡體以后,會使滑坡體內(nèi)的基質(zhì)吸力減小,有效應(yīng)力降低,同時,軟化泥化滑帶土,使粘土礦物發(fā)生水化作用導(dǎo)致粘聚力下降,從而改變坡體的力學(xué)性能。(3)利用Geo-studio軟件中的Seep模塊模擬庫水位下降對滑坡前緣滲流場的情況可知,庫水位下降到一段時間后,滑坡前緣土體浸潤線明顯滯后于庫水位的下降速率,浸潤線高于水位線,而遠(yuǎn)離庫水位的坡頂及滑坡上部,基本不受庫水的影響,庫水位下降速率越快,浸潤線滯后越嚴(yán)重,導(dǎo)致的水頭差越顯著,其形成的向下滲流力也就越大,對滑坡的穩(wěn)定性影響越大。(4)庫水位以每天下降0.6m和1.2m的過程中,李家灣滑坡的穩(wěn)定狀況處于穩(wěn)定和基本穩(wěn)定之間;而疊加3d暴雨強度85mm/d的情況,李家灣滑坡處于基本穩(wěn)定~欠穩(wěn)定狀態(tài)。(5)通過FLAC3D軟件對四種工況下的滑坡穩(wěn)定性的應(yīng)力、應(yīng)變場及剪切塑性區(qū)的數(shù)值模擬分析發(fā)現(xiàn),在工況I下,庫水位在下降過程中,滑坡前緣局部出現(xiàn)拉應(yīng)力集中帶,滑坡位移變化只發(fā)生在前緣附近,剪應(yīng)變增量集中在巖土分界面上,滑坡的變形破壞主要沿著主滑動面破壞;在工況III和IV下,前緣拉應(yīng)力分布范圍有所增大,中后部局部范圍有拉應(yīng)力分布,剪切塑性區(qū)在坡體表層有所延伸,并向深部發(fā)展。(6)通過分析李家灣滑坡三期治理工程的治理效果,根據(jù)《三峽庫區(qū)三期地質(zhì)災(zāi)害防治工程設(shè)計技術(shù)要求》的相關(guān)規(guī)定,提出李家灣滑坡治理工程的補強措施建議,在滑坡前緣高程177m布置一排26根抗滑樁支擋工程,在滑坡左側(cè)高程200m布置一排17根抗滑樁支擋工程,在滑坡后緣高程257m附近設(shè)置截排水工程。
[Abstract]:Lijia Bay landslides are located in the right bank slope of the three Dong village, Fengcheng village, Changshou District, Chongqing. The rainfall is abundant and the rainfall is large. The deformation of the study area is further developed by the fluctuation of the reservoir water level and rainfall. It is considered that there are a large number of houses in the study area, 368 people living in the residential and enterprise workers, and the longevity area. When the water supply pipeline is passed, the water supply pipeline bears the daily living water task of more than 50 thousand households in the long life area. If the landslide resurrection is unstable, it will directly threaten the safety of the lives and property of the residents and the workers and workers, and affect the normal daily life of the residents in the longevity area. Therefore, the resurrection mechanism of the old landslides is studied and the stability of the landslides is evaluated. It is of great practical significance. Through the analysis of the geological structure, hydrogeological characteristics and the development characteristics of the strong and weak deformation zone of the Lijia Bay landslide, this paper reveals the resurrection mechanism and the influencing factors of the landslide, and uses the Geo-studio software to simulate the seepage field of the main deformation area of the landslide, and obtains the change of the infiltration line under different working conditions. The pore water pressure contour map is used to evaluate the effect of the pore water pressure on the stability of the landslide. On this basis, the grey correlation degree theory is used to study the sensitive strength of the different shear strength indexes, the rainfall size and the reservoir water level height to the landslide stability. Finally, the FLAC3D numerical simulation is used to analyze the stress, strain field and plastic zone in the main deformation zone. The main results are as follows. (1) the Lijia Bay landslide occurred under the internal and external conditions of the landslide. The internal conditions included topography, geomorphology, geological structure, and slope structure characteristics, and the external conditions were mainly rainfall and river cutting. The slope body structure of the soft and hard interbedded sand mudstone is easy to be soft and weak. Under the rainstorm condition, the slope slides under the combined action of the hydrostatic pressure and the air gap pressure. (2) the resurrection of the Lijia Bay landslide is divided into 3 strong deformation zones and 1 weak deformation zones. The resurrection of the Lijia Bay landslide is caused by the change of the reservoir water level and the rainfall, among which the rainfall is the resurrection of the landslide. The main factors that induce the landslide are as follows: the rain infiltration reduces the shear strength of the soil, increases the weight of the slope, and thus increases the sliding force of the slope. After the infiltration of the unsaturated soil mechanics principle, the rain infiltration into the landslide body will reduce the matrix suction in the landslide body, reduce the effective stress, and soften the mud and slide the soil to make the clay stick. The hydration of soil minerals leads to the decrease of cohesive force and change the mechanical properties of the slope. (3) using the Seep module in Geo-studio software to simulate the seepage field in the front of the landslide, it is known that the soil infiltration line of the front of the landslide is obviously lagging behind the decline rate of the reservoir water level and the infiltration line is high after the reservoir water level drops to a period of time. At the water level line, the top of the slope and the top of the landslide far away from the reservoir water level are basically not affected by the reservoir water. The faster the decline rate of the reservoir water level is, the more serious the lag line is, the more significant the head difference is, the greater the downward seepage force is, the greater the effect on the stability of the landslide. (4) the reservoir water level is in the process of decreasing 0.6m and 1.2m every day, Li Jia Wan. The stability of the landslide is between the stability and the basic stability, and the Lijia Bay landslide is in the basic stable and unstable state when the 3D rainstorm intensity is 85mm/d. (5) the stress of the landslide stability, the strain field and the shear plastic zone of the four conditions are simulated by the FLAC3D software, and the reservoir water level is decreased under the working condition of I. During the process, the tensile stress concentration zone appears in the front of the landslide. The change of the landslide displacement only occurs near the front edge, and the shear strain increment concentrates on the geotechnical interface. The deformation and failure of the landslide is mainly destroyed along the main sliding surface. Under the working condition III and IV, the distribution range of the tensile stress in the front edge is increased, and the local range of the middle and rear parts has the tensile stress distribution and the shear stress distribution. The plastic zone extends in the surface of the slope and develops to the deep. (6) through the analysis of the treatment effect of the three period treatment project of the Lijia Bay landslide, according to the relevant regulations of the design technical requirements of the three geological disaster prevention and control engineering in the Three Gorges Reservoir area, the suggestion of strengthening the reinforcement measures of the Lijia Bay landslide control project is put forward, and a row of 26 of the elevation 177m of the landslide front is arranged in a row of 26. A row of 17 anti slide piles are arranged at the elevation 200m of the left side of the landslide, and a drainage project is set up near the elevation 257m of the rear edge of the landslide.
【學(xué)位授予單位】：成都理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P642.22

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本文編號：2038106