后压浆技术在钻孔桩基础应用中的思考和探索.docVIP

后压浆技术在钻孔桩基础 应用中的思考与探索 摘要： 本文就钻孔桩后压浆技术，从钻孔桩通病成因起，对后压浆技术的应用进行了思考分析。文章从后压浆形成桩头扩大头，桩身因受压力水泥浆泥浆护壁破坏后，形成枝节作用入手，详实阐述了后压浆技术的应用的作用、内涵及新亮点。作者根据目前桥梁桩基础检测的实际应用超身波测定的预置钢管，提出了从设计开始应将其考虑作为后压浆孔道，籍以提高钻孔桩基础的承载能力，降低工程成本这一新的思路，若这一思路能被设计人员接纳并采用，将是钻孔灌注桩施工的又一进步。 文章中就后压浆施工的机具设备及工艺流程均做了一一详述。 文章根据工地实例做了工程造价的对比计算，并以表格的形式加以表述。 Abstract: This article is about the technology of broach stake latter pressing slurry. The author began from the reasons of the problems of broach stake, studied the use of the technology of broach stake latter pressing slurry. This article started with the extend of head of the stake which forms latter pressing slurry, then the slurry destroyed because of the press to the stake, and formed breaches knots action. This article carefully expatiated the function , connotation and innovation of the thechnology of latter pressing slurry. According to the recent practice of detection of the base of stakes of bridges ,prefab steel tubs using ultrasonic detection., the author proposed that from the beginning of designing, it should be considered as orifice ,so as to heighten the carrying capacity and lower the cost of projects. If this new method can be accepted, it will be a progress of construction of broach stakes. This article introduced the equipments and technics of construct of latter pressing slurry in detail. In addition, this article did the contrastive calculation of construct cost according to construct examples, and used table to depict. 一、概述 1.1 钻孔灌注桩的特点： 钻孔灌注桩在近年来得到迅速发展，笔者曾在83年参与松花江公路大桥的建设，并较早的接触钻孔桩的实践，原用于桥梁基础的钻孔桩在近二十年的时间里得到了工程设计人员的青睐，大量应用于楼宇建筑的基础，其优势在于钻孔的直径可以选择、长度可调整等，故承载力较高。因其工作原理是钻削，故对相邻建筑影响小，不会造成隆起等负效应，危害小；且由于钻机钻具能随地质条件变异而变化，故桩长、桩径调整的余地大，能给设计人员更大的发挥空间，其优点之多不一一复述。钻孔桩虽然有以上诸多优点，但其在卵砾石层中钻孔困难，施工过程中由于诸多不确定因素造成的次品桩，其补救困难亦是钻孔桩的缺点。就目前已有的后压浆技术，从某种程度上讲，能针对桩底沉渣所造成的承载力下降，提出补救措施，或在设计时就考虑采用后压浆技术，提高桩的承载力，以及针对施工中产生的不合格桩，通过钻孔形式采用后压浆方法对桩身质量加以补救。 1.2 钻孔灌注桩主要质量通病与防治： 1.2.1桩底沉渣 a. 一般在钻孔桩钻孔清孔完成后，视其泥浆比重和孔中泥浆质量（即稠度），考虑可以吊放钢筋笼，浇筑水下混凝土，清孔后的泥浆质量因其在施