地基承载力机理及新计算方法  

Mechanism and new calculation method for bearing capacity of foundations

作　　者：宋二祥[1] 付浩 李贤杰 SONG Er-xiang;FU Hao;LI Xian-jie(Department of Civil Engineering,Tsinghua University,Beijing 100084,China)

机构地区：[1]清华大学土木工程系,北京100084

出　　处：《岩土工程学报》2022年第1期37-44,共8页Chinese Journal of Geotechnical Engineering

基　　金：国家重点研发计划(“973”计划)课题(2014CB047003);国家自然科学基金项目(51778339)。

摘　　要：地基承载力计算是土力学中的基本课题,但地基土自重对承载力的贡献一直未能较准确地予以计算,究其原因在于此部分的计算不是孤立的。为深入探讨地基承载力的机理及计算理论,首先,证明基础埋深相应超载及地基土重度对承载力的作用可分别转换为等效黏聚力及黏聚力随深度的增长率。随后,针对承受非偏心竖向荷载的条形基础下地基的整体剪切破坏,提出一种全新的地基极限承载力计算方法,特别是构造了一个可以综合考虑地基土强度、基础埋深超载及地基土重度影响的无量纲参数,进而给出统一考虑各有关因素的地基承载力计算公式,并对地基局部剪切破坏、非条形基础、倾斜荷载等复杂情况下利用本文公式进行地基承载力的计算给出建议。通过与精细数值方法计算比较,对所提出的计算方法进行了严格的检验,表明其正确性和高精度,同时也表明本文思路及所构造无量纲参数的合理性和正确性。此外,还与目前常用的太沙基解、Hansen解进行了比较讨论,表明所提出计算公式较现用公式有显著改进。The calculation of bearing capacity of foundations is a fundamental topic in soil mechanics.However,the contribution of the unit weight of the foundation soil to the bearing capacity cannot yet be satisfactorily calculated.The fundamental reason is that this part of bearing capacity is actually not independent,and consequently cannot be calculated separately.In order to study the mechanism of foundation bearing capacity and the relevant theory thoroughly,it is first revealed that the surcharge load corresponding to footing embedment and the unit weight of the foundation soil,multiplied by the soil strength parameter tanφ,can be treated respectively as the equivalent cohesion and the rate of cohesion increase along depth.Then a new method is developed for the general failure mode of strip footing under non-eccentric vertical loads.In this new method a non-dimensional parameter is defined to well reflect the influences of the soil strength and soil weight on the bearing capacity,and based on which a unified formula for the calculation of bearing capacity is established,in which the soil strength,the embedment depth of the footing and the soil weight are all considered as closely related elements.For the bearing capacity of foundation under other more complicated conditions,such as failure in local mode,different footing shapes,inclined loads etc.,the available methods of treatment can be still applied in combination with the newly developed formula.Careful comparison with the refined numerical calculations proves the reliability and high accuracy of the proposed formula,and at the same time it proves the rationality and correctness of the whole idea as well as the constructed non-dimensional parameter.Besides,comparisons are also made with the formulas by Terzaghi and Hansen to show the significant improvement of the proposed method over the formers.

关 键 词：地基承载力 统一计算公式 太沙基解 Hansen解 

分 类 号：TU470[建筑科学—结构工程]