兰州某深基坑的稳定性及变形规律研究
发布时间：2019-06-20 01:38
【摘要】：2013年兰州市委市政府为全面实现“三年有效缓解、五年明显改善”的畅交通目标,将畅交通工程列为服务人民的“一号工程”,围绕既定的“一横、三环、九纵”骨干路网体系,在城市核心区实施184个上跨下穿工程,同时地铁一号线、二号线一期工程全线展开,大批量的工程建设产生了大量的基坑工程问题。由于下穿工程大多位于城市中心区域的交通拥堵路段,场地狭窄、周边环境错综复杂,处理不当就会引发安全问题。本文以兰州市第一个下穿工程——天水路下穿读者大道车行地道基坑工程为研究背景,以理论分析、现场实测及数值模拟相结合的方法,利用MIDAS/GTS对基坑开挖的实际过程进行模拟分析,研究了基坑在实际开挖过程中支护结构的水平位移、周围地表沉降变形以及基坑坑底隆起变形的发生发展规律。同时,研究分析了开挖工序、桩体埋深、桩体直径、桩间距、钢支撑间距等因素对围护结构水平位移、周围地表沉降、基底隆起的变形影响规律,论文主要的研究内容及成果有:(1)查阅大量资料文献对国内及兰州地区基坑工程稳定性和变形规律的研究现状进行了总结,阐述了基坑稳定性计算、变形机理及变形计算的理论。(2)利用基坑稳定性分析计算软件对依托工程围护结构的整体稳定性、抗隆起稳定性、抗倾覆稳定性进行了验算分析,分析结果表明人工挖孔灌注桩加横向钢支撑的支护结构能够保证该基坑在开挖过程中的安全稳定。(3)数值模拟分析结果表明:在基坑开挖深度不大,未架设钢支撑之前,支护结构的水平位移表现为悬臂式位移;架设钢支撑后,支护结构的水平位移则发展为抛物线形位移。周围地表的沉降变形表现为距围护墙越远,沉降越小的勺形分布,在距围护墙约0.4-0.7倍的基坑开挖深度范围内,地表沉降值最大。(4)监测结果与数值模拟结果曲线对比分析表明:模拟曲线与实测曲线的变化规律相一致,且受到施工及降水等因素的影响,实测桩身最大水平位移为9.6mm,远小于警戒值30mm,说明此设计偏于安全。(5)对各影响因素的模拟分析表明:改变桩体埋深对周围地表沉降的影响不大,但对围护结构的水平位移影响较大;在一定的范围内,增加桩体直径可以有效的减小围护结构的水平位移以及周围地表的沉降变形,但对基底隆起变形的影响却十分有限;桩间距的增大会引起围护结构水平位移的增大,从而进一步引起周围地表沉降变形的影响范围和变形量。
[Abstract]:In 2013, in order to fully realize the smooth traffic goal of "three years of effective mitigation and five years of obvious improvement", the Lanzhou Municipal CPC Committee and Municipal Government listed the smooth traffic project as the "No. 1 project" to serve the people. Around the established "one horizontal, third ring, nine vertical" backbone network system, 184 upper-span and down-crossing projects were carried out in the urban core areas, while the whole line of the first phase of Metro Line 1 and Line 2 was launched. A large number of engineering construction has produced a large number of foundation pit engineering problems. Because most of the underpass projects are located in the traffic congestion sections in the central area of the city, the site is narrow and the surrounding environment is complex, which will lead to safety problems. In this paper, based on the research background of the foundation pit engineering of Tianshui Road, which is the first underpass project of Tianshui Road, the actual process of foundation pit excavation is simulated and analyzed by using the method of theoretical analysis, field measurement and numerical simulation, and the horizontal displacement of the supporting structure, the settlement deformation of the surrounding surface and the occurrence and development of the foundation pit bottom uplift deformation in the actual excavation process are studied. At the same time, the influence of excavation process, pile depth, pile diameter, pile spacing and steel support spacing on the horizontal displacement of enclosure structure, the settlement of surrounding surface and the deformation of foundation uplift is studied and analyzed. The main research contents and achievements of this paper are as follows: (1) the research status of stability and deformation law of foundation pit engineering in China and Lanzhou area is summarized, and the stability calculation of foundation pit is expounded. The deformation mechanism and the theory of deformation calculation are carried out. (2) the overall stability, uplift stability and overturning stability of the retaining structure relying on the engineering are checked and analyzed by using the software of foundation pit stability analysis. The analysis results show that the supporting structure of manual excavated cast-in-place pile and transverse steel support can ensure the safety and stability of the foundation pit during excavation. (3) the results of numerical simulation analysis show that the horizontal displacement of the supporting structure is cantilever displacement before the excavation depth of the foundation pit is small and the steel support is not installed. After the steel support is installed, the horizontal displacement of the supporting structure develops into a parabola displacement. The settlement and deformation of the surrounding surface shows that the farther away from the retaining wall, the smaller the spoon shape distribution, and the maximum surface settlement value is in the range of 0.4 脳 0.7 times the excavation depth of the retaining wall. (4) the comparison and analysis between the monitoring results and the numerical simulation results show that the simulation curve is consistent with the measured curve, and is affected by construction and precipitation. The maximum horizontal displacement of the measured pile is 9.6mm, which is much less than the warning value of 30mm, which indicates that the design is safe. (5) the simulation analysis of various influencing factors shows that changing the buried depth of the pile has little effect on the surrounding surface settlement, but has a great influence on the horizontal displacement of the enclosure structure. In a certain range, increasing the diameter of pile can effectively reduce the horizontal displacement of enclosure structure and the settlement and deformation of surrounding surface, but the influence on the deformation of foundation uplift is very limited, and the increase of pile spacing will lead to the increase of horizontal displacement of envelope structure, thus further causing the influence range and deformation of surrounding surface settlement and deformation.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU433;TU473.2
本文编号：2502809
[Abstract]:In 2013, in order to fully realize the smooth traffic goal of "three years of effective mitigation and five years of obvious improvement", the Lanzhou Municipal CPC Committee and Municipal Government listed the smooth traffic project as the "No. 1 project" to serve the people. Around the established "one horizontal, third ring, nine vertical" backbone network system, 184 upper-span and down-crossing projects were carried out in the urban core areas, while the whole line of the first phase of Metro Line 1 and Line 2 was launched. A large number of engineering construction has produced a large number of foundation pit engineering problems. Because most of the underpass projects are located in the traffic congestion sections in the central area of the city, the site is narrow and the surrounding environment is complex, which will lead to safety problems. In this paper, based on the research background of the foundation pit engineering of Tianshui Road, which is the first underpass project of Tianshui Road, the actual process of foundation pit excavation is simulated and analyzed by using the method of theoretical analysis, field measurement and numerical simulation, and the horizontal displacement of the supporting structure, the settlement deformation of the surrounding surface and the occurrence and development of the foundation pit bottom uplift deformation in the actual excavation process are studied. At the same time, the influence of excavation process, pile depth, pile diameter, pile spacing and steel support spacing on the horizontal displacement of enclosure structure, the settlement of surrounding surface and the deformation of foundation uplift is studied and analyzed. The main research contents and achievements of this paper are as follows: (1) the research status of stability and deformation law of foundation pit engineering in China and Lanzhou area is summarized, and the stability calculation of foundation pit is expounded. The deformation mechanism and the theory of deformation calculation are carried out. (2) the overall stability, uplift stability and overturning stability of the retaining structure relying on the engineering are checked and analyzed by using the software of foundation pit stability analysis. The analysis results show that the supporting structure of manual excavated cast-in-place pile and transverse steel support can ensure the safety and stability of the foundation pit during excavation. (3) the results of numerical simulation analysis show that the horizontal displacement of the supporting structure is cantilever displacement before the excavation depth of the foundation pit is small and the steel support is not installed. After the steel support is installed, the horizontal displacement of the supporting structure develops into a parabola displacement. The settlement and deformation of the surrounding surface shows that the farther away from the retaining wall, the smaller the spoon shape distribution, and the maximum surface settlement value is in the range of 0.4 脳 0.7 times the excavation depth of the retaining wall. (4) the comparison and analysis between the monitoring results and the numerical simulation results show that the simulation curve is consistent with the measured curve, and is affected by construction and precipitation. The maximum horizontal displacement of the measured pile is 9.6mm, which is much less than the warning value of 30mm, which indicates that the design is safe. (5) the simulation analysis of various influencing factors shows that changing the buried depth of the pile has little effect on the surrounding surface settlement, but has a great influence on the horizontal displacement of the enclosure structure. In a certain range, increasing the diameter of pile can effectively reduce the horizontal displacement of enclosure structure and the settlement and deformation of surrounding surface, but the influence on the deformation of foundation uplift is very limited, and the increase of pile spacing will lead to the increase of horizontal displacement of envelope structure, thus further causing the influence range and deformation of surrounding surface settlement and deformation.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU433;TU473.2
【参考文献】
相关期刊论文 前1条
1 周建武;楼晓明;;软黏土中预钻孔沉桩引起的土体隆起分析[J];岩土力学;2011年09期
，本文编号：2502809
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