板式中型桩复合基础抗拔承载力发挥特性数值分析

摘要

通过山西黄土地区现场载荷试验资料反演数值计算参数,在验证数值计算方案合理性的基础上,探讨了桩长、桩径、板基埋深和桩基布置形式等因素对上拔荷载作用下的板式中型桩复合基础承载力发挥的影响.结果表明:桩径、桩长、埋深及布桩数目的增加均可有效地提高复合基础整体承载力,但板基础及单桩承载力的发挥程度并未显著提高;对于2×2群桩基础,板基础承载力发挥系数可取0.70~0.80,单桩承载力发挥系数可取0.70~0.90;对于3×3群桩基础,板基础承载力发挥系数可取0.60~0.75;单桩承载力发挥系数可取0.65~0.76.计算结果可为板式中型桩复合基础在黄土地区工程应用中的承载力确定提供参考依据.%By means of conducting numerical analysis from the load test results of medium-sized pile cap foundation,the rationality of the numerical model and parameters were confirmed by field load test results. Numerical simulation was used to discuss the influences of pile diameter,pile length,buried depth and pile arrangement type on bearing characteristics of medium-sized pile cap foundation under uplift load.The results indicated that pile diameter,pile length,buried depth and pile arrangement type can improve bearing characteristics of composite foundation,but bearing capacity factor of raft and pile cannot significantly increase.For a 2×2 group pile foundation,bearing capacity factor of raft can be 0.70-0.80, bearing capacity factor of a single pile can be 0.70-0.90.For a 3×3 group pile foundation,bearing capacity factor of raft can be 0.60-0.75,bearing capacity factor of a single pile can be 0.65~0.76.The calculation results in this paper can provide reference for predicting bearing capacity of engineering application in medium-sized pile cap foundation.