岩溶地区桩基检测与缺陷处理研究

Pile testing and defect treatment in the karst area

摘要:

桩基是岩溶地区建筑基础最常用的形式之一，由于地质条件的复杂性、特殊性和无规律性，岩溶地区的桩基施工质量问题频发。岩溶地区桩基质量问题主要是桩身缺陷、桩身局部倾斜、桩底沉渣过厚以及桩底持力层不符合要求，常用的桩基检测方法包括高低应变法、超声法以及钻芯法，常用的处理方法采用高压注浆加固桩端持力层。结合深圳市龙岗区一岩溶强发育地区的工程实例，对岩溶地区桩基检测和缺陷处理的技术进行了探讨。岩溶地区桩基最常见的质量问题就是桩基持力层的缺陷，钻芯法不仅可以探明桩身范围内的缺陷程度和相对位置，更有利于查明桩底持力层范围内是否存在溶洞、破碎带以及软弱夹层。岩溶地区检测出桩基缺陷后，采用高压旋喷注浆的方式对缺陷桩进行加固处理，可使得原本破碎的持力层变得稳固，经再次检测合格后，能够继续满足原有荷载条件下的安全使用要求，可为类似岩溶桩基问题提供借鉴。

Abstract:

The pile foundation is the most commonly used foundation for buildings in the karst area. The pile foundation construction quality problem is common due to the complexity， particularity， and irregularity of the geological conditions. The main quality problems with the pile foundation in the karst area are pile defects， local pile shaft inclination， thick settlements， and unqualified pile foundation supporting layer. The common test methods for pile foundation include the high and low strain method， ultrasonic method， and coring method. With conventional treatment， high pressure grouting is used to reinforce the pile supporting layer. In regard to a project completed in the karst area in the Longgang District of Shenzhen， an in-depth exploration of pile testing and defect treatment is conducted. The common quality problem is the defect with the pile supporting layer in the karst area. With the coring method， not only the severity and the relative location of the defect can be detected in the pile， but also presence of the karst cave， broken zone， and the weak inter-layers. High pressure jet grouting was used to strengthen the piles with defects and cement the supporting broken zone. Inspection showed that the piles can meet the original load requirement. It can provide reference for similar projects.