發(fā)布時間：2018-01-25 00:46

  本文關鍵詞： 映秀 巖漿巖 邊坡 發(fā)育規(guī)律 地震 動力響應 數(shù)值模擬　出處：《成都理工大學》2013年碩士論文　論文類型：學位論文

【摘要】：在我國西部峽谷區(qū)，邊坡地震動力響應問題突出。汶川地震誘發(fā)了大量邊坡次生災害，加劇了震區(qū)的破壞和損失，震后余震頻發(fā)，使得部分邊坡再次破壞失穩(wěn)。因此，對震區(qū)邊坡地震動力響應規(guī)律的研究具有重要的理論意義和現(xiàn)實意義。 本文以汶川地震震中區(qū)映秀-北川斷裂上盤元古代巖漿巖邊坡為研究對象，在詳實的現(xiàn)場調(diào)查資料基礎上，利用統(tǒng)計分析和數(shù)值模擬分析的方法，對區(qū)內(nèi)邊坡地質(zhì)災害的發(fā)育規(guī)律及影響因素進行分析，進一步研究了地震荷載和邊坡地形地貌條件對邊坡地震動力響應規(guī)律的影響，并以老虎嘴崩塌為例，模擬分析其動力響應規(guī)律。研究成果如下： （1）研究區(qū)屬中--高山峽谷地貌，地層巖性以巖漿巖為主，地質(zhì)構造復雜，地震活動頻繁，河谷走向與優(yōu)勢節(jié)理方向呈大角度相交。 （2）區(qū)內(nèi)中-大型崩塌占震后邊坡地質(zhì)災害的90%，主要沿岷江干流及其支流兩岸呈線狀分布，干流右岸崩塌無論是密集程度還是規(guī)模上都大于左岸（背坡效應），邊坡破壞模式以滑移式和傾倒式為主。 （3）隨著地震波周期的增大，加速度放大系數(shù)極值將逐漸減��；速度和水平位移極值隨著周期的增大而增大，當周期達到一定值后水平位移極值開始減小。地震波振幅對邊坡動力響應分布規(guī)律影響較小，振幅的增減基本不改變邊坡的加速度、速度和位移分布形式，但三者的極值隨著地震波振幅的增加逐漸增大。 （4）地震荷載作用下邊坡動力響應程度為凹形直線形凸形，邊坡失穩(wěn)多發(fā)育于對地震波有顯著放大效應的部位。當坡高小于400m時，邊坡加速度放大系數(shù)、速度和水平位移值均從坡腳至坡頂呈線性逐漸增大，三者的極值隨著坡高的增大而增大；當坡高大于400m時，邊坡加速度放大系數(shù)、速度和水平位移值從坡腳至坡頂呈非線性變化，具體表現(xiàn)為先增大后減小再增大的循環(huán)變化規(guī)律。邊坡地震動力響應程度與坡度不存在明顯的線性關系，坡度的改變不會引起邊坡動力響應分布規(guī)律的變化，坡度為46～65°的邊坡動力響應最為明顯。 （5）老虎嘴崩塌模型系統(tǒng)不平衡力與輸入地震波呈正相關關系，系統(tǒng)不平衡力經(jīng)過一段時間的振動變化后最終趨于零；隨著坡高的增加，加速度、速度放大系數(shù)逐漸減小，，并在坡頂位置有所增大，豎向加速度、速度放大系數(shù)整體大于水平方向；邊坡位移主要集中于崩塌堆積體中后部及前緣坡腳位置；地震波對邊坡應力分布影響較小，模型中最大主應力分布整體較均勻，其值隨著深度的增大而增加，在基巖陡崖坡腳形成小范圍的壓應力和剪應力集中；堆積體前緣斜坡坡腳首先出現(xiàn)剪應變增量，然后向后緣擴展，最終在堆積體中后部基覆界面形成一條貫通的剪應變增量條帶；堆積體中部分單元達到塑性狀態(tài)，但未產(chǎn)生塑性破壞；老虎嘴崩塌邊坡處于穩(wěn)定狀態(tài)。
[Abstract]:In the western canyon region of China, the problem of slope dynamic response is prominent. Wenchuan earthquake induced a large number of slope secondary disasters, aggravated the damage and losses in the earthquake area, and the aftershocks occurred frequently after the earthquake. Therefore, it is of great theoretical and practical significance to study the seismic dynamic response law of the slope in the earthquake area. This paper takes Yingxiu-Beichuan fault slope of Proterozoic magmatic rock in the epicenter of Wenchuan earthquake as the research object, based on the detailed field investigation data, using the methods of statistical analysis and numerical simulation analysis. The development law and influencing factors of slope geological hazard in this area are analyzed, and the influence of earthquake load and slope topographic condition on slope seismic dynamic response is further studied, and the case of Laohuzui collapse is taken as an example. The dynamic response law is simulated and analyzed. The results are as follows: 1) the study area belongs to the mid-high mountain canyon landform, the stratigraphic lithology is dominated by magmatic rock, the geological structure is complex, the seismic activity is frequent, and the valley strike intersects with the dominant joint direction at a large angle. (2) Middle-large scale collapses account for 90% of the geological hazards of the slope after the earthquake, mainly distributed linearly along the main stream of Minjiang River and its tributaries. The collapse of the right bank of the main stream is larger than that of the left bank in terms of density and scale (back slope effect), and the slope failure mode is mainly sliding and toppling. 3) with the increase of seismic wave period, the maximum value of acceleration magnification factor will gradually decrease. The maximum value of velocity and horizontal displacement increases with the increase of the period. When the period reaches a certain value, the extreme value of horizontal displacement begins to decrease. The amplitude of seismic wave has little effect on the distribution of slope dynamic response. The increase or decrease of amplitude does not change the distribution of acceleration, velocity and displacement of slope, but the extreme values of them increase with the increase of amplitude of seismic wave. 4) the dynamic response degree of slope under earthquake load is concave linear convex, and the slope instability is mostly developed in the position where the seismic wave is magnified significantly. When the slope height is less than 400m. The acceleration magnification factor, velocity and horizontal displacement of the slope increase linearly from the foot of the slope to the top of the slope, and the maximum values of the three increase with the increase of the height of the slope. When the slope height is greater than 400m, the acceleration magnification factor, velocity and horizontal displacement of the slope show nonlinear variation from the foot of the slope to the top of the slope. There is no obvious linear relationship between slope dynamic response and slope, and the change of slope will not cause the change of slope dynamic response distribution law. The dynamic response of the slope with a slope of 46 擄65 擄is the most obvious. 5) the unbalance force of the system is positively correlated with the input seismic wave, and the unbalance force of the system tends to zero after a period of vibration change. With the increase of slope height, the acceleration and velocity magnification coefficient decrease gradually, and increase at the top of the slope. The vertical acceleration, the velocity magnification factor is larger than the horizontal direction. The displacement of slope is mainly focused on the position of the back part and the foot of the front slope in the middle part of the collapse deposit. Seismic wave has little influence on slope stress distribution, and the maximum principal stress distribution in the model is uniform as a whole, and its value increases with the increase of depth, forming a small range of compressive stress and shear stress concentration at the base of steep slope of bedrock. At first, the shear strain increment appears at the slope foot of the front slope of the accumulation body, and then extends to the back edge, and finally a through shear strain increment strip is formed at the interface of the back base of the accumulation body. Some of the elements in the accumulated body reached the plastic state, but no plastic failure occurred. The slope of Tiger mouth collapse is in a stable state.
【學位授予單位】：成都理工大學
【學位級別】：碩士
【學位授予年份】：2013
【分類號】：TU45

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