【摘要】 为提高冻土地区桩基极限承载力试验结果的准确性,以高温、高含冰量冻土桩基为例,利用室内冻土桩基模型试验开展了不同加载方式下冻土桩基极限承载力的研究,各加载方式分别为现行规范中已在采用的快速维持荷载法、慢速维持荷载法及稳定维持荷载法这一新方法。提出充分考虑冻土流变性的S-P-T曲面,相对传统的以S-P曲线为基础判断桩基极限承载力的方法,当考虑桩土流变效应时,宜考虑时间效应而采用S-P-T曲线来确定冻土桩基的极限承载力,以此为基础,提出了在不同加载方式下确定极限承载力时桩基破坏的新形式判断准则,并对各种加载方式下冻土桩基的极限承载力进行了分析。结果表明:桩土流变效应能够有效地影响桩基的承载力,现有规范中的快速维持荷载法和慢速维持荷载法由于没能考虑或充分考虑桩土流变效应,导致所得出的桩基极限承载力均不同程度地偏大;为了克服上述不足,建议用修正系数使现有冻土地区桩基承载力检测规范满足桩土流变效应。更多还原

【Abstract】 In order to enhance the accuracy of experimental results about ultimate bearing capacities of pile foundation in permafrost region,taking the warm and ice-rich permafrost pile foundation as an example,the research on the ultimate bearing capacities of pile foundation in permafrost region under different loading methods was carried out,by dint of indoor model experiment.The loading methods in the current specifications included fast,slow and stable loadkeeping methods.The S-P-T hook face in consideration of the rheological property of permafrost was proposed.Relative to the traditional judgment methods of the ultimate bearing capacities based on S-P curve,S-P-T curve,taking time effect into consideration,is much better to determine the bearing capacities of pile foundation in the permafrost, when considering rheological effect of piles and soil.On this basis,new damage criteria of determining the ultimate bearing capacities of pile foundation under different loading methods were put forward,and the ultimate bearing capacities of pile foundation in the permafrost region under different loadingmethods were analyzed.The results show that pile soil rheological effect can effectively influence the bearing capacity.The ultimate bearing capacities calculated by dint of fast and slow loadkeeping methods in the current specifications are larger than actual values,seemingly thanks to failing to consider or fully consider the rheological effect of piles and soil.In order to overcome the shortcoming,it is necessary to deploy correction coefficient to make the existing specifications of detecting bearing capacities in permafrost region meet the rheological effect of piles and soil method.更多还原