砂性土中钻孔灌注桩施工质量控制要点

孙静

摘 要：钻孔灌注桩是目前国内公路桥梁和房屋建筑等土木工程中应用最为广泛的桩基基础类型之一。钻孔灌注桩不仅可有效解决抗震、承载等问题，还具备施工噪音小、挤土效应低等环境保护问题。随着高层建筑的发展，建筑基础和桩基深度显著增加。灌注桩在进入砂性土层时，其成孔和成桩质量以及承载力都将受到砂的影响。本文则通过工程实践所得，对砂性土中钻孔灌注桩的施工难点进行了分析，着重指出了泥浆系统在保证成孔和成桩质量中的重要性，概要总结了相对应的控制措施，可为今后类似桩基基础的施工和验收提供借鉴。

关键词：钻孔灌注桩；砂性土层；泥浆系统

Abstract： bored pile is the current domestic highway bridge and building construction and civil engineering of the most widely used type of pile foundation. Bored pile not only can effectively solve the problems such as earthquake， bearing， but also have low construction noise， low soil squeezing effect environmental protection problem. With the development of high-rise buildings， the building foundation and pile depth increased significantly. Bored pile in sandy soil， the hole and into a pile quality and capacity will be influenced by the effect of the sand. In this paper， through the engineering practice income， on sandy soil in the construction of bored pile difficulty undertook an analysis， pointed out emphatically the mud system to ensure the quality of pile hole and into the importance are summarized， the corresponding control measures， for similar pile foundation construction and acceptance to provide reference.

Key words： bored pile， sandy soil， mud system

引言

灌注桩是指通过机械钻孔、钢管挤土或人力挖掘等手段在地基土中形成桩孔，并在其内放置钢筋笼、灌注混凝土而做成的桩。依照成孔方法不同，灌注桩可分为沉管灌注桩、钻孔灌注桩和挖孔灌注桩等多种。其中，钻孔灌注桩因其工艺特点，可不受桩径和桩深的限制，适用于粘性土、粉土、砂土、填土、碎石类，以及地质条件比较复杂、夹层多和风化不均、软硬变化较大的岩层，故广泛应用于高层、超高层的建筑物和重型构筑物中。但由于地下施工的不可预计因素，加之钻孔灌注桩的工序繁多，造成其质量离散性相对较大，容易出现塌孔、缩孔、孔斜、沉渣过大以及断桩、夹泥等等质量问题，而这些问题之间往往存有很大的关联性和系统性，成孔质量为首要关键。……