【作者】 尹光明；

【导师】 傅鹤林；

【作者基本信息】 中南大学 ， 道路与铁道工程， 2012， 博士

【摘要】 在城市用地日益紧张的情况下,经常遇见在已有建筑周边进行深基坑开挖,并施做支护结构。基坑周边土体应力状态由静止土压力状态逐步转向主动土压力状态,导致支护结构向基坑内位移,较大的水平位移最终导致基坑影响范围内的地面出现沉降。这种沉降的大小除了与基坑开挖深度和范围有关外,还与基坑支护类型、周围地质条件和支护结构的变形大小相关。尽管基坑工程事先都进行了精心设计,但由于土体有很多不确定因素,基坑支护有关的理论还不完善,因此展开城市隧道建设临近建筑物超深基坑支护技术研究十分必要。为此,本文结合国家自然科学基金“基于能量渐进耗散的流固耦合作用下土石混合体滑坡演化机制研究”(50878213/E080603),依托重庆南坪城市隧道建设临近建筑物超深基坑工程,在基坑工程监测的基础上,基于模糊神经网络理论,借助极限分析法,结合非线性有限元及随机介质理论,展开城市隧道建设临近建筑物超深基坑支护理论与安全控制技术研究,形成完整的评价体系,确保隧道建设临近建筑物超深基坑施工安全和邻近结构物的稳定。主要工作内容为：(1)基于模糊神经网络理论,构建基坑支护方法选择的模型,实现基坑支护选择和设计的最优化。(2)采用极限平衡法对基坑及其支护结构进行稳定性研究,计算其稳定系数；通过使用变位分析对支护结构的变形和内力进行计算,对设计参数进行研究,并根据研究结果对设计进行调整和优化,确保基坑支护结构和周边建筑物的安全。(3)使用有限元法对不同支护形式下基坑动态施工进行三维数值模拟,得到各级开挖下基坑和基坑支护结构的位移、应力场情况,并比较未采用支护结构下基坑位移、应力场情况,以此来研究基坑对周边建筑物的影响。将计算得到的数据与实际监测的结果进行对比分析。(4)采用随机介质理论,对基坑工程开挖引起的地表移动与变形的两种因素(疏水以及基坑侧壁失去支撑)的地表移动与变形的随机介质模型加以研究,并将计算数据与工程实测结果加以比较,以保证工程的安全。(5)结合爆破振动测试,应用小波包理论对实测峰值振速进行分析,与爆破效应的数值模拟结果进行对比分析,得到峰值振速预报值,在城市隧道建设临近建筑物超深基坑支护技术研究与安全性评价的基础上,对复杂周边环境超深基坑开挖扰动效应下的施工方案、施工工艺进行优化,最终达到指导施工的目的。更多还原

【Abstract】 Increasing tensions in the urban land situation, often encountered in the existing buildings surrounding the deep excavation, and the facilities to do the supporting structure. Slope soil stress state by the state of earth pressure at rest and gradually turned to the active earth pressure state, leading to the supporting structure inside the pit displacement, horizontal displacement of the larger sphere of influence leading to pit the ground subsidence. In addition to this settlement the size of the excavation depth and scope, but also relate to the type of foundation pit, surrounded by geological conditions and the deformation size of the supporting structure. Although the excavation have been carefully designed in advance, but because of the pit there are many uncertain factors in the soil and the theory for excavation is not enough perfect, so the city started construction of the tunnel near the building ultra-deep foundation pit research is necessary. So, this paper is combined whit the National Natural Science Foundation of "Gradual Dissipation of Energy Based on Solid-fluid Interaction under A Mixture of Earth and Rock Slide Mechanism of Evolution, relying on the tunnel construction near Chongqing Nanping city building ultra-deep excavation, whit the excavation monitoring, by the use of limit analysis, basing on Nonlinear Finite Element and Random Medium Theory, settling about tunnel construction near the city building ultra-deep excavation research and safety assessment, a complete evaluation system to ensure that the tunnel construction near the building ultra-deep excavation safety and the stability of adjacent structures. Main tasks are:(1) On the base of fuzzy and neutral net, the selection model of pit-reinforcement is set up, the optimum design and selection of pit reinforcement will be realized.(2) Using Limit equilibrium analysis, stochastic medium theory and nonlinear finite element techniques for urban tunnel construction near the building ultra-deep excavation for a comprehensive study of technical and safety evaluation for Nanping station cut to provide ultra-deep excavation technical guidance and security guarantees. (3) Retaining wall for the piles, anchor piles pull the board rib bolting, gravity retaining wall supporting four kinds of support form had been gone about limit balance analysis and deformation analysis under gradually excavation disturbed. Analysis considered a variety of conditions and the surrounding complex environment. Studies have shown that the higher pit stability factor, better stability, the smaller supporting structure of the internal forces and deformation. A reasonable foundation pit form, protecting surrounding buildings during construction and after the completion of the stability and security.(4) Nanping station cut for ultra-deep pit in Anchor piles, sheet, plate bolt type three supporting rib form of dynamic simulation, and compared with the actual monitoring analysis, comparison indicates that the model accurately. Anchor pulling piles, piles board two kinds of support form in the excavation process, the supporting structure deformation, mainly in the upper part of the deformation, a small settlement around the pit, a small impact on the surrounding buildings. Rib bolting plate form in the excavation process, the supporting structure deformation, the upper bolt by force, the lower anchor force is small, a small settlement around the pit, a small impact on the surrounding buildings.(5) Combined with blasting monitor,and wavelet packet theory is applied in peak vibrating velocity,compared with numerical simulation results,and got the point peak vibrating velocity is simulated in this paper. Urban tunnel construction near the ultra-deep foundation pit support in building technology research and safety evaluation on the basis of the complexity of the surrounding environment deep foundation excavation disturbance effect under construction program construction process optimization, and ultimately to guide the construction purpose.更多还原