长短桩复合地基受荷性状的影响因素分析

采用大型有限元软件ABAQUS,对不同褥垫层模量、厚度、短桩模量及基础上不同的荷载对刚柔性长短桩复合地基的长桩与土的应力比、短桩与土的应力比、长短桩应力比、基础沉降的影响及其规律进行了分析.数值分析表明:垫层的存在增大了地基的沉降,可调节复合地基中桩土应力的分配;随着垫层模量的增加,长桩桩身应力增加,短桩应力减小;增加短桩的刚度,复合地基的沉降减少;随着基础顶面荷载的增加,桩土应力比增大,位移差也增大.结合武汉某住宅小区的长短桩静载荷的现场监测数据,分析了工程中长桩与土、短桩与土、长短桩应力比的变化规律.数值分析和现场监测数据分析结果可为该类型地基的设计和施工提供依据.

Influence factor analysis of load-bearing character of long-short piles for composite foundation

By using the finite element software ABAQUS,the effects and laws of cushion modulus,cushion thickness,short pile modulus,pressure of cap-padding on the stress ratio of long pile to soil,short pile to soil,long pile to short pile,settlement of cap are analysed respectively.Numerical analysis results indicate: The existence of cushion increases the settlement of foundation,so as to adjust the assignment stress between piles and soils.Pile body stress of long pile is increased;while that of short pile is fallen with the increasement of cushion modulus.Settlement of composite foundation is decreased with the increase of short pile rigidity.The stress ratio of pile to soil and difference of displacement are raised with the increasement of load on the top of foundation.Based on the in-situ measurement of pressures by static loading tests of a practical engineering in Wuhan,load mechanics of long pile and soil,short pile and soil,long-short piles are analyzed.The numerical analysis results and in-situ tests will provide references for future design and construction of this kind of composite foundation.