孤石群地层高层建筑桩基础施工设计优化与应用分析

Design optimization and application analysis of pile foundation construction of high-rise buildings in isolated rock group regions

孤石地层的存在是困扰桩基础施工的主要难题,其不仅关系到桩基稳定,更关系到工程的投资。为合理解决此类问题,以深圳某高层建筑桩基础施工工程为研究背景,此工程地层存在分布范围广且尺寸大的孤石群。根据总体地勘资料、设计要求和现场条件,提出了孤石群地层中桩基础施工设计优化方案,并对其进行了经济性分析。所得到的主要结论如下:原设计桩基极有可能穿过巨大孤石,浪费明显,成本高;对于全风化和强风化花岗岩层内,采取桩底分别进入孤石内4.5m和3.7m深,锚杆进入岩层长度在3~8m的方案;优化施工方案后桩基和锚杆数量分别占其总数量的57.34%和5.04%,相比原设计方案节约造价1559.38万元和449.22万元,同时桩基的质量检测均符合要求。

The isolated rock region is a key challenge for the construction of pile foundation construction project,which not only related to the stability of the pile foundation,but also related to the construction project costs.To reasonably overcome this issue,taking the pile foundation construction project of a high-rise building in Shenzhen as the research background,the stratum of this project has a wide distribution range and large size isolated rock group.Based on all the geological exploration data,design requirements and site conditions,the optimized construction design of pile foundation in isolated rock group region was proposed.Meanwhile,the economy of the proposed plan was also analyzed.The main conclusions drawn are as follows:the original design of pile foundation is very likely to pass through huge isolated rock,the waste is obvious,and the cost is high.For the fully weathered and strongly weathered granite layer,the scheme that the pile bottom intrusions into the isolated rock are 4.5m and 3.7m respectively and the length of rock intrusion by the anchor should be within 3~8m was adopted.The number of pile foundation and bolt accounts for 57.34%and 5.04%of the total number of the optimized construction scheme,and the cost was saved by 15.5938 million yuan and 4.4922 million yuan compared with the original design scheme,meanwhile,the quality test of pile foundation meets the requirements.