长江大跨UHV塔基桩土变形协调机制及其应用研究

发布时间：2018-08-17 18:14

【摘要】：地基稳定性问题是指在建筑物荷载作用下,地基土体能否保持稳定。若地基稳定性不能满足要求,地基在构筑物荷载作用下将产生局部或整体剪切破坏,这种破坏将影响构筑物的安全与正常使用。特高压长江大跨输电塔基施工难度大、沉降变形控制严,尤其对于河相特殊的地质环境,沉降控制至关重要。因此对于特高压大跨输电塔塔基特别是地形复杂的长江岸边输电塔塔基施工影响的研究具有积极的意义。基于桩土变形协调思路,本文针对灵州到绍兴±800kV特高压直流输电线路长江大跨塔基工程,在桩基础施工已经完成的前提下研究了特高压大跨塔基桩土变形协调机制及桩基优化,在分析论证了原有设计方案存在很大安全风险的前提下并提出了两种加固优化方案,研究成果表明:(1)原有设计基础无法满足约300t的施工荷载要求,施工可能导致铁塔倾斜、沉降、失稳破坏等风险,很有必要对塔基进行加固处理。(2)塔基桩土变形协调破坏主要表现为前期工况桩以贯入式切入土体,随荷载增大逐步变更为浅部土体和基础结构受损,承台整体下沉、褥垫层破坏及周边土体隆起,塔基无法承受上部过载作用而局部失稳破坏。(3)垫层加固与土体注浆联合加固这两种方案对塔基进行加固处理能很好的改善塔基承载能力,满足施工要求。(4)在上部竖向荷载作用下,桩、土及承台共同作用,变形协调。(5)通过数值计算和现场监测得出的结论对实际工程提出了一些建议。
[Abstract]:The problem of foundation stability refers to whether the foundation soil can maintain stability under the action of building load. If the stability of the foundation can not meet the requirements, the local or global shear failure will occur under the load of the structure, which will affect the safety and normal use of the structure. The construction of ultra-high pressure Yangtze River transmission tower is difficult and the settlement deformation is controlled strictly. Especially for the special geological environment of river facies, settlement control is very important. Therefore, it is of positive significance to study the influence of the construction of UHV long span transmission tower, especially on the complex topography along the Yangtze River. Based on the idea of pile-soil deformation coordination, aiming at the Yangtze River large-span tower foundation project from Lingzhou to Shaoxing 卤800kV UHV direct current transmission line, this paper studies the pile soil deformation coordination mechanism and pile foundation optimization under the premise that pile foundation construction has been completed. Based on the analysis and demonstration of the great safety risk of the original design scheme, two reinforcement and optimization schemes are put forward. The results show that: (1) the original design foundation can not meet the construction load requirement of about 300t, and the construction may lead to the tilt of the iron tower. It is necessary to reinforce the tower foundation because of the risk of settlement and instability. (2) the deformation and coordinated failure of the pile-soil in the tower foundation is mainly manifested as the pile cutting into the soil in the early working condition, and gradually changing to the shallow soil and the foundation structure with the increase of the load. The whole sinking of the cap, the failure of the cushion and the uplift of the surrounding soil, The tower foundation can not withstand the action of the upper overload and local instability. (3) the combination of cushion reinforcement and soil grouting can improve the tower foundation bearing capacity. (4) under the action of vertical load in the upper part, the pile, soil and cap act together, and the deformation is coordinated. (5) some suggestions for practical engineering are put forward by the conclusion of numerical calculation and field monitoring.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM754

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