Influence of intermediate principal stress on correction formula of bearing capacity of rock foundation

Author(s):  
Zhang Zhi-Min ◽  
Lei Wei-Dong
Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1019
Author(s):  
Zongyuan Ma ◽  
Faning Dang ◽  
Hongjian Liao

The bearing capacity for footings is a fundamental scientific problem in civil engineering. The evaluation of the bearing capacity of footings usually does not take into account the effect of the intermediate principal stress. In practice, the intermediate principal stress has certain influences on the strength of geomaterials (e.g., rock and soil) or concrete. In this paper, a series of numerical solutions are presented to evaluate the bearing capacity of footings in a soft rock foundation via a two-dimensional finite difference code (FLAC) with a strain hardening/softening constitutive model based on the unified strength theory (UST). The values of the bearing capacity factor Nc and Nγ for strip, circular and square footings in a soft rock foundation were evaluated using the strain hardening/softening constitutive model. The effect of the intermediate principal stress on the bearing capacity of strip, circular and square footings in a soft rock foundation was analyzed. The results of the numerical computation show that the intermediate principal stress has a significant influence on the bearing capacity and failure mechanisms of a soft rock medium. The influence of the intermediate principal stress on the peak and residual values of the bearing capacity for a strip footing is much greater than for circular and square footings. Research works for the reasonable estimation of the bearing capacity of footings in soft rock are facilitated by this study.


2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Qing Yan ◽  
Junhai Zhao ◽  
Changguang Zhang ◽  
Jintai Wang

The reasonable determination of ultimate bearing capacity is crucial to an optimal design of shallow foundations. Soils surrounding shallow foundations are commonly located above the water table and are thus in an unsaturated state. The intermediate principal stress has an improving effect on the unsaturated soil strength. In this study, the ultimate bearing capacity formulation of strip foundations in unsaturated soils is presented by using Terzaghi’s theory. The unified shear strength equation of unsaturated soils under a plane strain condition is utilized to capture the intermediate principal stress effect. Furthermore, two profiles of matric suction are considered and a hyperbolic function of the friction angle related to matric suction (φb) is adopted to describe strength nonlinearity. The validity of this study is demonstrated by comparing it with model tests and a theoretical solution reported in the literature. Finally, parameter studies are conducted to investigate the effects of intermediate principal stress, matric suction, and base roughness on the ultimate bearing capacity of strip foundations. Besides, the effect of strength nonlinearity is discussed with two methods representing the angle φb.


2012 ◽  
Vol 256-259 ◽  
pp. 662-665
Author(s):  
Xiao Yan Luo ◽  
Wei Ping Liu

This study presents a simplified analytical method for predicting the ultimate strength of compressed concrete filled square steel tube columns based on the triple shear unified yield criterion. Based on the triple shear unified yield criterion theory solutions of thick tube, the calculation formulas of axial bearing capacity of the concrete-filled square steel tube columns were deduced with considerations of the restriction effects of steel tube and the effects of the intermediate principal stressed. The results show that the intermediate principal stress effect parameter b has influences on the ultimate bearing capacity. The formulas in the paper have significance in exerting material potential and save material.


2013 ◽  
Vol 639-640 ◽  
pp. 770-773
Author(s):  
Xiao Yan Luo ◽  
Wei Ping Liu

Based on the triple shear unified yield criterion, the mechanical behavior of the concrete-filled steel tube columns was analyzed. The calculation formulas of axial bearing capacity of the concrete-filled steel tube columns were deduced with considerations of the restriction effects of steel tube and the effects of the intermediate principal stressed. The results show that the intermediate principal stress effect parameter b has influences on the ultimate bearing capacity. With the increase of the intermediate principal stress effect parameter b, the ultimate bearing capacity of the concrete-filled steel tube columns increases too. The results show that formula deduced in the paper has good applicability and the solution has an important practical value.


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