（1 铜陵市建设投资控股有限责任公司， 铜陵 244000； 2 铜陵市建筑工程施工图设计文件审查有限公司， 铜陵 244000；3 铜陵市建设工程质量监督监测有限公司， 铜陵 244000）

［摘要］结合某33层住宅桩端基岩厚度小于3d和5m这一问题，详细分析了其产生原因及处理方法。其原因为：基岩面倾斜、超前钻或桩基的倾斜导致超前钻见岩标高与桩基全断面见岩标高相差较大，且未重新进行补钻；或桩端3d和5m以内有溶洞，但超前钻擦溶洞边而过从而未能发现溶洞。其处理方法是：利用桩基承载力计算没有计入侧阻力、大多数桩承载力未用足等有利因素，结合不同位置的溶洞对桩承载力影响程度的不同进行综合分析，从而减少处理数量；当必须处理时，可采用“高压注浆置换溶洞充填物”的方法处理，也可采用“新增桩基+托换梁”的方法处理。

［关键词］溶洞； 桩端基岩厚度； 超前钻； 基岩面倾斜； 见岩标高； 高压注浆法

中图分类号：TU473.1+6文献标识码：A文章编号：1002-848X(2019)17-0136-06

Analysis and treatment of insufficient pile-end bedrock thickness of a 33-storey residential building in karst area

Chu Jun1, Li Guosheng2,3

（1 Tongling Construction Investment and Holding Co., Ltd., Tongling 244000， China; 2 Tongling Building Engineering Drawings Design Documents Examination Co., Ltd., Tongling 244000， China; 3 Tongling Construction Engineering Quality Supervision and Testing Co., Ltd., Tongling 244000， China）

Abstract:The pile-end bedrock thickness of a 33-storey residential building was less than 5m and 3 times of pile diameter. The causes and treatment methods for this problem were analyzed in detail. There were two main reasons. First, bedrock surface inclination, advance drilling or pile foundation inclination led to the great difference between rock elevation of advanced drilling and rock elevation of full cross-section pile foundation, and no additional drilling was carried out when this problem was identified. Second, there were karst caves within distance of 5m and 3 times of pile diameter from the pile end, but karst caves was not found because advanced drilling might brush against the edge of karst caves. The treatment methods were as follows. Some favorable factors could be manipulated such as side resistance not taken into consideration in the calculation of bearing capacity of pile foundation and the  bearing capacity of most piles not used fully, and comprehensive analysis was carried out according to the different influences of karst caves at different locations on pile bearing capacity, thus reducing the number of treatments. When the problem had to be dealt with, the method of “replacing karst cave fillings with high-pressure grouting” or the method of “adding pile foundation + underpinned beam” could also be used.

Keywords:karst cave; pile-end bedrock thickness; advanced drilling; bedrock surface inclination; rock elevation; high-pressure grouting method