大直径袋装混凝土灌注桩现场试验分析

发布时间：2019-07-06 11:03

【摘要】：我国内陆盐渍土环境中，在荷载作用、冻融循环、干湿交替、卤水腐蚀等多因子复合劣化作用下，混凝土遭受腐蚀破坏非常强烈。目前对于内陆强、过盐渍土地区多腐蚀因子综合作用下混凝土耐久性问题认识仍不成熟，还处于不断总结、研究阶段。本文对大直径袋装混凝土灌注桩进行现场试验研究分析，其目的是解决在内陆盐渍土地区桥涵基础使用的大直径混凝土灌注桩的防腐蚀问题。本文采用“三布两膜”复合土工布制作的专用防腐袋将混凝土桩体包裹起来，阻止盐渍土和地下水（卤水）等腐蚀物质接触和侵入桩体，保证桩体混凝土不受到腐蚀，从而延长桩体的使用寿命。在实验室检验大直径袋装混凝土灌注桩专用防腐袋袋体材料的各项性能指标。共设计3根桩长45m、桩径1.2m的大直径袋装混凝土灌注桩，并在本试验依托工程所在地进行试验性施工研究，采用桩承载力自平衡测试法对桩体承载力进行测试。通过现场试验，对“大直径袋装混凝土灌注桩”这一新技术的操作性、可靠性、实用性、桩理论基桩承载力与实际承载力的差别等方面，，进行试验性的研究总结，为在实际工程中的全面应用做一些探索性、基础性的工作，为确保察格高速公路桥涵基础工程高效率、高质量、按期完工积累实践经验。实验室检验结果表明“三布两膜”复合土工布的强度特性、布与桩侧土界面摩擦特性、抗渗性、耐久性等各项指标均满足大直径袋装混凝土灌注桩设计、施工要求，“三布两膜”复合土工布的设计方案合理、科学，满足大直径袋装混凝土灌注桩使用要求。试桩结果显示，大直径袋装混凝土灌注桩承载力高，完全满足工程要求，且能有效降低地下混凝土工程对混凝土自身的要求和附加的防腐蚀措施，经济效益优势明显，可以在内陆盐渍土地区推广使用。本文总结了中交第一公路勘察设计研究院在察尔汗盐湖至格尔木高速公路工程实践中取得的部分研究成果和经验。
文内图片：

图片说明：拟建项目位置
[Abstract]:In the environment of inland saline soil in China, the corrosion damage of concrete is very strong under the combined deterioration of load, freeze-thaw cycle, dry and wet alternation, brine corrosion and so on. At present, the understanding of concrete durability under the comprehensive action of multiple corrosion factors in inland strong and over-saline soil areas is still immature, and it is still in the stage of continuous summary and research. In this paper, the field test and analysis of large diameter bagged concrete cast-in-place pile are carried out, the purpose of which is to solve the corrosion prevention problem of large diameter concrete cast-in-place pile used in bridge and culvert foundation in inland saline soil area. In this paper, a special anticorrosion bag made of "three cloth and two films" composite geotextile is used to wrap up the concrete pile body to prevent the contact and invasion of saline soil and groundwater (brine) into the pile body, so as to ensure that the pile concrete is not corroded, so as to prolong the service life of the pile body. The performance indexes of special anticorrosive bag material for large diameter bagged concrete pile were tested in laboratory. A total of three large diameter bagged concrete cast-in-place piles with a length of 45m and a diameter of 1.2m were designed. The experimental construction research was carried out on the basis of the project site, and the bearing capacity of the pile was tested by the self-balance test method of pile bearing capacity. Through the field test, the operation, reliability and practicability of the new technology of "large diameter bagged concrete cast-in-place pile", the difference between the bearing capacity of the pile theory and the actual bearing capacity of the pile are studied and summarized experimentally. some exploratory and basic work is done for the comprehensive application in the practical engineering, and practical experience is accumulated in order to ensure the high efficiency, high quality and timely completion of the bridge and culvert foundation project of Chage Expressway. The laboratory test results show that the strength characteristics, friction characteristics, impermeability and durability of "three cloth and two film" composite geotextile meet the design and construction requirements of large diameter bagged concrete cast-in-place pile, and the design scheme of "three cloth and two film" composite geotextile is reasonable, scientific and meets the requirements of large diameter bagged concrete cast-in-place pile. The results of pile test show that the bearing capacity of large diameter bagged concrete cast-in-place pile is high, which fully meets the engineering requirements, and can effectively reduce the requirements of underground concrete engineering for concrete itself and additional corrosion prevention measures, the economic benefits are obvious, and it can be popularized and used in inland saline soil areas. This paper summarizes some research results and experiences obtained by Zhongjiao No.1 Highway Survey and Design Research Institute in the engineering practice of Chaerhan Salt Lake to Golmud Expressway.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U416.1;U445.551

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