本文關鍵詞： 筲箕窩滑坡 成因機制 數(shù)值模擬 復活機制 穩(wěn)定性評價　出處：《成都理工大學》2015年碩士論文　論文類型：學位論文

【摘要】：筲箕窩老滑坡位于四川省綿陽市北川羌族自治縣三坪村,處于龍門山構造帶內(nèi),構造背景復雜,為中陡傾千枚巖質(zhì)順層斜坡失穩(wěn)破壞后堆積而成,其變形破壞類型為“滑移-彎曲-潰決”型,失穩(wěn)規(guī)模約700萬m3。在“5.12”汶川地震中,老滑坡堆積體體上出現(xiàn)若干條短小的張拉裂縫;地震后經(jīng)過多年降雨作用,尤其為2013年7月的特大暴雨后,坡體上發(fā)育多條橫向的長大張拉裂縫,復活跡象明顯。老滑坡復活將危及坡體上的居民生命和財產(chǎn)安全,中斷通向上游村落的重要交通道路,并對老麂溝溝口居民造成威脅。因此,研究該滑坡的復活機制及穩(wěn)定性具有重要的實際意義,同時補充了地震引發(fā)滑坡堆積體復活的研究,對類似老滑坡堆積體的復活及穩(wěn)定性的分析具有一定的參考價值。本文在收集研究區(qū)相關地質(zhì)關資料,整理勘查資料,對滑坡區(qū)工程地質(zhì)條件、滑坡結構特征、變形破裂特征進行分析的基礎上,采用地質(zhì)-力學的方法分析老滑坡的形成機制,通過地質(zhì)分析與數(shù)值模擬相結合的方法研究了滑坡在地震與暴雨作用下的復活機制,進而用定性與定量兩種方法對滑坡整體與局部的穩(wěn)定性進行評價,并提出了防治措施。主要研究成果如下:(1)分析滑坡的基本特征與滑坡外圍的類似千枚巖斜坡的變形特征,并結合滑移-彎曲的地質(zhì)力學模型計算極限彎曲段長度,確定筲箕窩滑坡為中陡傾千枚巖質(zhì)順層斜坡失穩(wěn)破壞后堆積而成,變形破壞模式為“滑移-彎曲-潰決”。(2)“5.12”地震中,老滑坡堆積體在地震波作用下變形破壞主要變現(xiàn)為松動、破裂,在后部高陡的部位與前部微地貌呈凸起形的部位產(chǎn)生若干條短小的橫向裂縫;地震后受多年降雨作用影響,尤其在2013年7月特大暴雨期間,滑坡有明顯的復活跡象,主要表現(xiàn)坡體上出現(xiàn)多條長大的橫向裂縫與下錯陡坎,并具有一定分區(qū)性。根據(jù)坡體結構特征與變形破裂特征將老滑坡分為1#、2#、3#三個復活區(qū)。(3)老滑坡體結構較松散,為滑坡復活提供了不良的地質(zhì)基礎;在地震作用下,坡體出現(xiàn)裂縫,且結構更加松散,為后期降雨入滲提供良好的滲流通道。降雨入滲坡體后轉(zhuǎn)化為地下水,對坡體加載,產(chǎn)生靜水壓力與滲透力,并且軟化滑帶,造成下滑力增加而抗滑力減小,滑坡堆積體開始出現(xiàn)蠕滑變形,導致老滑坡的復活。根據(jù)滑坡的變形特征,推斷滑坡度堆積體變形破壞的模式為“蠕滑-拉裂-剪斷”模式。利用Flac3D(有限差分法)模擬分析在地震與暴雨作用下滑坡堆積體復活機制,通過對數(shù)值模擬結果分析得出:在地震作用下,堆積體的位移較小,塑性變形幾乎在整個滑坡堆積體出現(xiàn),塑性破壞在坡體上零星出現(xiàn);老滑坡堆積體在降雨作用下位移量較大,出現(xiàn)一定區(qū)域的塑性破壞,并且在滑坡后部與前部形成相對集中的剪切應變帶,降雨作用誘發(fā)堆積體復活。(4)通過定性分析與采用Morgenstern-Price極限平衡法分析老滑坡堆積體局部及整體穩(wěn)定性。老滑坡整體在天然工況下處于穩(wěn)定狀態(tài),在暴雨與地震工況下處于基本穩(wěn)定狀態(tài)。各復活體在天然工況下處于基本穩(wěn)定-穩(wěn)定狀態(tài),除1#復活體在暴雨工況下處于不穩(wěn)定,其余在暴雨與地震工況下基本處于欠穩(wěn)定-基本穩(wěn)定狀態(tài)。通過穩(wěn)定的敏感性分析,穩(wěn)定性系數(shù)隨內(nèi)聚力與內(nèi)摩擦角呈上升趨勢,其中內(nèi)摩擦角對滑坡穩(wěn)定性的影響更大。二維滲流場與應力場耦合數(shù)值模擬分析五十年一遇的單次最大降雨與5天連續(xù)最大降雨條件下的穩(wěn)定性情況。單次降雨結果顯示:單次最大降雨方式為垂直入滲,引起坡表的應力應變改變,容易引發(fā)表層的溜滑。5天連續(xù)降雨結果顯示:降雨前2天雨水作用方式為垂直入滲為主引起滑體容重增加,降雨后3天雨水作用形式為滲透作用和一定的浮托作用;耦合計算顯示降雨作用使坡體整體應力增加,滑帶處最大剪應力增大,在后部與前部形成兩個貫通的剪應變帶,后部的最大剪應變量值較前部的大,剪應變帶未整體貫通,驗證滑坡失穩(wěn)破壞為“蠕滑-拉裂-剪斷”模式。(5)在滑坡穩(wěn)定性計算結果的基礎上,并結合滑坡變形特征、失穩(wěn)破壞模式、巖土特征、空間發(fā)育特征及受害對象的分布等特點提出滑坡的防治方案為抗滑樁+排(截)水溝。
[Abstract]:The old landslide is located at three Shaoji nest village in Sichuan city of Mianyang province Beichuan Qiang Autonomous County, is located in the Longmen mountain tectonic belt, tectonic background complex, as the steep bedding layer phyllite slope instability damage accumulation, deformation and failure type "slip bending outburst" type, instability of the size of about 7 million m3. in the "5.12 Wenchuan earthquake", the old landslide body appeared on a number of short cracks; after the earthquake, after years of rainfall, especially for the torrential rain in July 2013 after the slope on the development of a number of horizontal tensile cracks grew up, raised significantly. Signs of revival of old landslide will endanger the slope residents on the safety of life and property, important way to interrupt traffic upstream of the village, and pose a threat to the old Deer Valley residents. Therefore, it has important practical significance to study the stability and the revival mechanism of the landslide, and adding earthquake Study on the resurrection of the landslide, which has a certain reference value for similar analysis of old landslide accumulation and stability of resurrection bodies. Based on the relevant data collected in the study area geological exploration data, consolidation, engineering geological conditions of landslide, landslide structure, foundation deformation and fracture characteristics were analyzed, using the method of geomechanics the analysis of the formation mechanism of old landslide, based on geological analysis and numerical simulation study of the landslide revival in the earthquake and rainstorm under the action mechanism, and then using qualitative and quantitative methods of two landslide overall and local stability evaluation, and puts forward the preventive measures. The main results are as follows: (1) the deformation characteristics of slope and landslide characteristics similar to phyllite surrounding landslide analysis, combined with the geological mechanics model of slip - bending length limit calculation, determine the Shaoji nest Landslide is steep bedding layer phyllite slope instability damage accumulation, deformation and failure mode of "sliding and bending - break." (2) "5.12" earthquake, the old landslide under earthquake wave deformation and failure of the mainshow is loose, broken, several short transverse cracks in the rear part and the front of the high and steep micro landforms were convex parts; after the earthquake affected by years of rainfall, especially in July 2013 during the torrential rain, landslides have obvious signs of resurrection, a plurality of transverse cracks and grew up under the fault scarp occurred mainly on the slope, and has a certain area according to the. Structural characteristics of slope deformation and fracture characteristics of the slope is divided into 1#, 2#, 3# three wards. (3) the old landslide body structure is loose, provides a good foundation for the geological landslide; in the earthquake, cracks in the slope, and the structure is more loose, For the latter part of the rainfall infiltration provide good seepage channel. Rainfall infiltration into slope groundwater, the slope of loading, hydrostatic pressure and penetration, softening and sliding zone, sliding force caused by increased anti slide force, landslide began to creep deformation, leading to the old landslide according to the resurrection. The deformation characteristics of the landslide, landslide accumulation of inference of the deformation and failure model for creep cracking and shearing "model. Using Flac3D (finite difference method) simulation analysis of landslide debris in the earthquake and rainstorm revival mechanism, based on the numerical simulation results show that under the earthquake, the accumulation of small displacement of body the plastic deformation accumulation almost throughout the landslide, the plastic damage in sporadic slope; the old landslide in rainfall displacement is large, plastic damage area, and in the rear and front landslide Formation of shear strain is relatively concentrated, the effect of rainfall induced accumulation of resurrection. (4) through the qualitative analysis and the Morgenstern-Price method of limit equilibrium analysis of the old landslide is local and overall stability. The old landslide is in the stable state in the natural condition, is in a stable state in the rainstorm and seismic conditions. The complex in vivo the natural condition is stable and stable state, in addition to 1# resurrection is unstable in heavy rain conditions, the rest in the heavy rain and earthquake conditions is less stable to stable state. Through the sensitivity analysis of stability, stability coefficient with the cohesion and internal friction angle increased, the influence of internal friction angle of landslide the stability should be greater. And simulate the stability of the single maximum rainfall analysis of fifty years and 5 days of continuous maximum rainfall conditions numerical two-dimensional seepage field coupling force field The single rainfall situation. Results show that the single biggest rainfall pattern for vertical infiltration, slope surface caused by stress and strain change, easily lead to slippery surface.5 days of continuous rainfall showed that rainfall 2 days before the rain to the role of vertical infiltration mainly caused by landslide bulk density increased, the 3 day after the rain drop rain effect for the penetration and float over certain extent; coupled calculation shows that the effect of rainfall the slope stress increases, the slide zone of maximum shear stress increases in the rear and the front two through the formation of shear strain, maximum shear strain value than the rear part, the shear strain with the overall link up verify the landslide failure as "creep cracking and shearing" model. (5) based on the calculation result of landslide stability, and combined with the characteristics of landslide deformation, failure modes, geotechnical characteristics, the characteristics of spatial distribution characters and victims etc. The prevention and control scheme of the landslide is the anti slide pile + row (cut) ditch.

【學位授予單位】：成都理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P642.22

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