本文關(guān)鍵詞： 泥巖滑坡 碎石土滑坡 成因機理 數(shù)值模擬 穩(wěn)定性分析　出處：《青海大學》2017年碩士論文　論文類型：學位論文

【摘要】：西寧市位于湟水河河谷內(nèi)與山間丘陵邊緣地區(qū),為低山丘陵及河谷平原,特有的地形地貌、地質(zhì)構(gòu)造等地質(zhì)環(huán)境,使得西寧市內(nèi)多種地質(zhì)災害頻發(fā)。通過現(xiàn)場實地地質(zhì)調(diào)查及結(jié)合調(diào)查報告研究結(jié)果表明:新近泥巖滑坡共有49處占西寧市地區(qū)的新近總滑坡的73.1%;新近碎石土滑坡共有10處占新近總滑坡的14.9%,成為威脅人類生命財產(chǎn)的主要地質(zhì)災害之一。因此,西寧市泥巖及碎石土滑坡成因機理研究對西寧市滑坡地質(zhì)災害的評價、分析、預警和防治可提供參考,具有實際意義。本文選取以張家灣磚廠滑坡為代表的泥巖滑坡及以付家寨滑坡為代表的碎石土滑坡為研究對象,通過實地滑坡剖面勘查和已有的調(diào)查報告,確定滑坡模型以及模型力學參數(shù),結(jié)合FLAC3D強度折減法及SLIDE極限平衡法,對典型的泥巖及碎石土滑坡在天然和飽和條件下做出系統(tǒng)而全面的穩(wěn)定性及成因機理分析。取得的認識如下:(1)西寧市地質(zhì)災害調(diào)查統(tǒng)計新近滑坡共有67處,按滑體性質(zhì)可分為土質(zhì)滑坡、泥巖滑坡、碎石土滑坡三類,其中泥巖滑坡地層主要以古近系(E)、新近系(N)、白堊系(K)的泥巖、砂巖及石膏巖為主,占新近總滑坡的73.1%;碎石土滑坡地層母巖均為古近系(E)泥巖、砂巖、石膏巖地層,巖性主要為碎屑巖、含鹽礦物為主,占新近總滑坡的14.9%。(2)西寧市泥巖及碎石土滑坡,在構(gòu)造運動影響下,受控于北川河西岸斷裂、湟水河斷裂、南川河斷裂、沙塘川斷裂帶。(3)泥巖及碎石土滑坡成因機理:張家灣磚廠泥巖滑坡,由于后緣陡坡在自重應力影響下形成拉裂縫,巖體內(nèi)發(fā)育的節(jié)理裂隙面成為優(yōu)勢拉裂和剪切面,為降水提供了下滲通道,使得滑坡后緣上部黃土的孔隙水、含水量大大增加,破壞了滑坡的穩(wěn)定性,最終滑坡后緣失穩(wěn)發(fā)生崩塌;付家寨碎石土滑坡,由于湟水河的快速下切使得坡體內(nèi)鹽分的流失加劇,且泥巖本身遇水軟化特性較強,變形能不易積累,坡體便以小規(guī)模崩塌的形式不斷釋放能量并堆于坡腳,形成了坡體現(xiàn)有的這一特殊物質(zhì)結(jié)構(gòu)特征,在集中降水等條件下坡體內(nèi)鹽分不斷釋出,并于相對隔水層形成滑動剪切面,最終產(chǎn)生滑坡災害。(4)泥巖及碎石土滑坡穩(wěn)定性分析結(jié)果表明:在天然及飽和條件下,張家灣磚廠滑坡整體穩(wěn)定性系數(shù)分別為1.290、1.160,說明滑坡整體處于穩(wěn)定狀態(tài),在強度折減法與極限平衡法對比分析中,初步判斷3個監(jiān)測點中,可以得出監(jiān)測點A處于隨時失穩(wěn)狀態(tài),監(jiān)測點B、C穩(wěn)定性較好,但不排除人為開挖邊坡及強降水等因素對該滑坡的影響,而導致的再次災害,這與實地野外調(diào)查結(jié)果一致;付家寨滑坡整體穩(wěn)定性系數(shù)分別為1.110、1.080,說明滑坡整體處于穩(wěn)定狀態(tài),在強度折減法與極限平衡法對比分析中,初步判斷監(jiān)測點A,滑坡后緣中部的穩(wěn)定性較差,屬于隨時失穩(wěn)狀態(tài),這與特殊的地層巖性及降水有直接的關(guān)系。
[Abstract]:Xining City is located in the Huangshui River Valley and the hilly margin of the mountains. It is a low mountain hill and valley plain with unique topography and geomorphology, geological structure and other geological environments. The results of field geological investigation and investigation report show that there are 49 new mudstone landslides which account for 73.1% of the total recent landslide in Xining city and 73.1% of the new gravel landslide in Xining City, and the results of field geological investigation and investigation report show that there are 49 new mudstone landslides in Xining City, which account for 73.1% of the total recent landslide. A total of 10 landslips accounted for 14. 9% of the total recent landslides, becoming one of the major geological hazards threatening human life and property. Study on the genetic Mechanism of mudstone and Gravel landslide in Xining City the evaluation, analysis, early warning and prevention and control of landslide geological hazards in Xining City can be used as a reference. This paper selects the mudstone landslide represented by Zhangjiawan Brick Factory landslide and the gravel landslide represented by the Fujiazhai landslide as the research object, and through the field landslide section survey and the existing investigation report, this paper selects the mudstone landslide as the representative of Zhangjiawan brick factory landslide and the gravel landslide represented by the Fujiazhai landslide. The landslide model and its mechanical parameters are determined, combined with FLAC3D strength reduction method and SLIDE limit equilibrium method. A systematic and comprehensive analysis of the stability and genetic mechanism of typical mudstone and gravel landslides under natural and saturated conditions is made. According to the nature of the sliding body, it can be divided into three types: soil landslide, mudstone landslide and gravel landslide. The mudstone landslide strata are mainly composed of mudstone of Paleogene, Neogene, Cretaceous K), sandstone and gypsum rock. 73.1% of the total recent landslide; the parent rock of the lithotriptic landslide is Paleogene (E) mudstone, sandstone, gypsum rock formation, lithology is mainly clastic rock, salt mineral is dominant, and it accounts for 14.9.2% of the recent total landslide) Xining mudstone and macadam landslide. Under the influence of tectonic movement, controlled by the fault in the west bank of Beichuan River, the Huangshuihe fault, the Nanchuan River fault, the Shatangchuan fault zone and the sand Tangchuan fault zone, the formation mechanism of mudstone and gravel landslide: Zhangjiawan Banchang mudstone landslide, Due to the formation of tensile cracks in the steep slope of the rear edge under the influence of gravity stress, the fracture plane developed in the rock body becomes the dominant tensile crack and shear surface, which provides a seepage channel for precipitation, which makes the pore water and water content of the loess in the upper part of the landslide increase greatly. It destroyed the stability of the landslide, and finally the instability of the back edge of the landslide collapsed. Due to the rapid downcutting of the Huangshui River, the loss of salt in the slope was aggravated, and the mudstone itself was characterized by strong softening of water, and the deformation could not be easily accumulated. The slope body releases energy continuously in the form of small scale collapse and heaps on the foot of the slope, which forms the special material structure characteristic of the slope. Under the condition of concentrated precipitation and other conditions, the salt in the slope body is continuously released, and the sliding shear surface is formed in the relative water-isolated layer. The results of landslide stability analysis of mudstone and gravel soil show that under natural and saturated conditions, the overall stability coefficient of Zhangjiawan brick factory landslide is 1.290 / 1.160, which indicates that the whole landslide is in a stable state. In the comparative analysis of strength reduction method and limit equilibrium method, it can be concluded that the monitoring point A is in a state of instability at any time, and the stability of monitoring point BCC is good, among the three monitoring points, it is preliminarily judged that the monitoring point A is in a state of instability at any time. However, the influence of man-made excavation slope and heavy precipitation on the landslide is not excluded, which is consistent with the field investigation results, and the overall stability coefficient of the Fujiazhai landslide is 1.110 ~ 1.080, which indicates that the whole landslide is in a stable state. In the comparative analysis of strength reduction method and limit equilibrium method, the stability of monitoring point A and the middle of the back edge of landslide is poor, which is in the state of instability at any time, which is directly related to the special stratigraphic lithology and precipitation.
【學位授予單位】：青海大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：P642.22

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