基于单桩Q-S曲线实测数据的群桩沉降分析

Settlement Behavior of Pile Group Based on single pile Q-S Curve

摘要:

群桩沉降预测一直是桩基设计中的难点，在国家地基规范、桩基规范和一些地方地基规范中均引入了沉降地区经验系数来加以修正，而这些修正系数变化范围太大。实际上，群桩基础沉降与桩基实际特性、施工方法和实际土层状况等密切相关，而单桩试桩曲线包含了丰富的桩土相互作用信息，在一定程度上直接反应了现场土质的力学性态且包含了桩土相互作用信息，但目前单桩试验曲线一般只应用于验证单桩承载力设计值，很少直接用于群桩沉降计算中。本文基于此提出了利用单桩Q-S曲线来推求群桩沉降。考虑到目前桩基理论计算出来的相互作用系数夸大了群桩间的相互作用，因此本文收集了77组单群桩沉降实测资料，其中71组用于统计分析得出群桩沉降比公式，最后通过6组实例分析，将本文方法计算结果与实测值进行了比较，其计算值与实测值比值的均值为1.46，计算值与实测值符合程度较好，表明该法具有较强的适用性。

Abstract:

In the geotechnical engineering design, it was difficult yet to estimate the settlement of pile group. Empirical coefficient is adopted to correct pile group settlement in national and regional codes, such as Code for design of building foundation and Technical code for building pile foundation. Great attention should be paid to the relationship between pile settlement and pile engineering practice, because pile and soil medium characteristic, relationship of pile top load and displacement and construction influence are all embodied in pile static load test. So it’s more reasonable that static load test results, that is static load test curve, should be combined with the analysis of pile group settlement. Then calculation method of pile group settlement applied with static load test results is proposed . many researches show pile group interaction theory overestimates interaction effect in pile group, this paper collects 77 observational examples including single pile settlement and pile group settlement, there are 71examples are used in calculating settlement ratio. Lastly six examples are analyzed with pile group settlement method applied with Q-S curve. Analysis results show the method is reasonable, more accurate and has strong regional applicability.