【摘要】：隨著高等級公路不斷向地形條件復(fù)雜的西部地區(qū)延伸,在建有橋梁的斜坡地區(qū)發(fā)育著一系列不同規(guī)模的滑坡地質(zhì)災(zāi)害。滑坡災(zāi)害不僅威脅到了周圍的居民生命財(cái)產(chǎn)安全,由于斜坡的不穩(wěn)定會促使橋梁產(chǎn)生負(fù)面的影響,給橋梁的安全運(yùn)行帶來了很大的威脅;另外,斜坡上的橋基在施工、運(yùn)行中與土體之間存在著樁-土相互作用,反過來給斜坡的穩(wěn)定性帶來一定的影響。所以針對橋址區(qū)滑坡災(zāi)害,本文首先從理論上分析了在斜坡上的橋基受力特點(diǎn)以及斜坡上橋基-土體之間的相互作用,對比分析了斜坡地段橋基與平坦地段橋基受力狀態(tài)的區(qū)別,同時(shí)對滑坡誘發(fā)因素作了具體分析;然后以棕樹凼大橋滑坡工程實(shí)例為依托采用有限元方法對橋址區(qū)老滑坡啟動機(jī)理、抗滑樁位置的選擇進(jìn)行了數(shù)值模擬;最后運(yùn)用蒙特卡羅和層次分析法方法對棕樹凼大橋滑坡進(jìn)行了風(fēng)險(xiǎn)評估計(jì)算,確定了滑坡災(zāi)害的風(fēng)險(xiǎn)等級。通過以上步驟,本來論文得出以下幾點(diǎn)結(jié)論:(1)斜坡上橋基的受力狀態(tài)有其特殊性而不同于平坦地段:斜坡上橋基起到了承受上部結(jié)構(gòu)荷載和坡后土體下滑力,具有“承載抗滑”的雙重特點(diǎn)。(2)由于斜坡一側(cè)臨空面的存在,橋基四周土體不再是半無限空間體,所以存在“陡坡效應(yīng)”現(xiàn)象,橋基所受的地基抗力有一定程度的弱化。(3)誘發(fā)滑坡產(chǎn)生的因素眾多,可以分為兩大類:外部因素(地形地貌、地層構(gòu)造、氣象水文、地震作用、人類活動),內(nèi)部因素(滑坡土體結(jié)構(gòu)、坡面形態(tài)),有這些因素的作用才導(dǎo)致了滑坡的產(chǎn)生。(4)通過數(shù)值模擬,確定棕樹凼大橋老滑坡的啟動機(jī)理為牽引式,是由于坡體前緣開挖逐漸引起的整個(gè)滑坡的失穩(wěn)破壞。(5)以棕樹凼大橋滑坡為例,對與牽引式滑坡在采取抗滑樁支擋的位置進(jìn)行了優(yōu)化,得出在橋基前部設(shè)置抗滑樁起到抗滑效果更好,限制橋基區(qū)土體的位移變形。(6)對棕樹凼大橋滑坡災(zāi)害進(jìn)行了危險(xiǎn)性分析:得出其失穩(wěn)概率為0.7785;同時(shí)對人口、房屋建筑、交通設(shè)施作了易損性分析。(7)在危險(xiǎn)性分析和易損性分析的基礎(chǔ)上,對棕樹凼大橋滑坡的風(fēng)險(xiǎn)值作了計(jì)算,得出了災(zāi)害風(fēng)險(xiǎn)等級為Ⅲ級。
[Abstract]:As the highway continues to extend to the western region with complex terrain conditions, a series of landslide geological hazards of different scales are developed in the slope area with bridges under construction. The landslide disaster not only threatens the safety of the residents' lives and property, but also brings a great threat to the safe operation of the bridge because of the instability of the slope. In addition, the bridge foundation on the slope is under construction. There is pile-soil interaction between soil and operation, which in turn has a certain influence on the stability of slope. Therefore, in view of the landslide disaster in the bridge site area, this paper first theoretically analyzes the stress characteristics of the bridge foundation on the slope and the interaction between the bridge foundation and soil on the slope. The difference between the stress state of the bridge foundation in the slope section and that of the bridge foundation in the flat section is analyzed, and the induced factors of the landslide are analyzed concretely. Secondly, based on the example of Changshutang Bridge landslide project, the starting mechanism of the old landslide and the selection of the anti-slide pile are numerically simulated by using the finite element method. Finally, the risk assessment and calculation of landslide of Changshutang Bridge are carried out by using Monte Carlo and Analytic hierarchy process (AHP) method, and the risk grade of landslide disaster is determined. Through the above steps, the following conclusions are drawn: (1) the stress state of the bridge foundation on the slope has its particularity and is different from the flat section: the bridge foundation on the slope has played a role in bearing the superstructure load and the sliding force of the soil behind the slope. (2) because of the existence of one side of the slope, the soil around the bridge is no longer a semi-infinite space body, so there exists the phenomenon of "steep slope effect". The ground resistance of bridge foundation is weakened to a certain extent. (3) there are many factors that induce landslide, which can be divided into two categories: external factors (topography and geomorphology, stratigraphic structure, meteorology and hydrology, earthquake, etc.) Human activities), internal factors (landslide soil structure, slope shape), the role of these factors to cause the landslide. (4) through numerical simulation, determine the Changshutang Bridge landslide starting mechanism is traction, This is due to the instability of the whole landslide caused by the excavation of the front edge of the slope body. (5) taking the Changshutang Bridge landslide as an example, the position of the anti-slide pile supporting the landslide with the traction type is optimized. It is concluded that the anti-slide pile in the front of the bridge foundation has better anti-slide effect and limits the displacement and deformation of soil in the bridge foundation area. (6) the hazard analysis of landslide disaster of Changshutang Bridge is carried out: the probability of instability is 0.7785; at the same time, for the population and housing, The vulnerability analysis of traffic facilities is made. (7) on the basis of hazard analysis and vulnerability analysis, the risk value of Changshutang Bridge landslide is calculated, and the disaster risk grade is obtained to be grade 鈪，

本文編號：2155043