岩溶地区高层建筑刚性桩复合地基现场试验研究  

Field testing of rigid pile composite foundation for high-rise buildings in karst area

作　　者：陶景晖[1,2] 金如元 陆飞[2] 穆保岗[2] 卢中强[1] 戴国亮[2] 

机构地区：[1]江苏省建筑设计研究院有限公司,江苏南京210019 [2]东南大学土木工程学院,江苏南京210096

出　　处：《建筑结构学报》2017年第6期163-174,共12页Journal of Building Structures

基　　金：国家重点基础研究发展计划(973计划)项目(2013CB036304);江苏省建筑设计研究院有限公司科研项目(B2017-004)

摘　　要：某高层建筑建造于岩溶场地,采用刚性桩复合地基。在现场开展了大型坑下综合性原位试验,包括多项载荷试验、桩与土的应力测试以及沉降观测等。运用BOTDA分布式光纤技术,获得复合地基桩身应力及桩侧摩阻力连续分布曲线。基于试验数据,对复合地基的荷载传递机制、荷载分担变化与发展规律、桩与土承载力发挥状况等进行了分析,研究了土层注浆和桩底后注浆对复合地基承载力与应力分布的影响。研究表明:增强体采用非挤土置换成桩工艺,对桩间土具有加固效果;桩底后注浆对复合地基的加固效果主要体现在加载后期的较高荷载水平下;土层注浆在提高桩间土和复合地基承载力的同时,降低了桩、土相对刚度,总体上有利于发挥土的承载作用;土层注浆对桩侧正、负摩阻力发挥均具有作用,可减少荷载经桩传递产生的下卧层附加应力,有利于下伏溶洞的安全。根据研究结果,给出了采用土层注浆时复合地基承载力发挥系数的建议值。The rigid pile composite foundation is applied in a high-rise building built in a karst site. Comprehensive large-scale in-situ tests, including various loading tests, stress tests of piles and soil, and settlement observations were performed. Continuous distribution curves of stress and lateral friction of piles were obtained by using the BOTDA distributed optical fiber technology. Based on the test data, the loading transfer mechanism, change and development law of load sharing, and load-bearing development of piles and soil were analyzed. Moreover, the effects of soil grouting and pile bottom post-grouting technology on bearing capacity and stress distribution of the composite foundation were studied. The study results show that the reinforcement using replacement pile-forming without soil compaction technology has a strengthening effect on the soil among piles. The reinforcing effects of pile bottom post-grouting on the composite foundation are achieved mainly in higher loading level at the later loading stage. While improving bearing capacities of both soils among piles and composite foundation, soil grouting can reduce the relative stiffness of pile- soil, which is helpful to play the bearing role of soils in general. Soil grouting has effects on both positive and negative lateral friction of piles, and can reduce the substratum additional stress transferred along piles, which is beneficial to the safety of karst caves under the composite foundation. According to the study results, the suggested bearing capacity coefficient values of composite foundation when soil grouting is used are given.

关 键 词：高层建筑 岩溶 刚性桩复合地基 现场试验 BOTDA 土层注浆 

分 类 号：TU473.16[建筑科学—结构工程]