Discussion: Comparison of European bearing capacity calculation methods for shallow foundations

Author(s):  
J.-G. Sieffert ◽  
C. Bay-Gress
2021 ◽  
Vol 11 (24) ◽  
pp. 11829
Author(s):  
Ana Alencar ◽  
Ruben Galindo ◽  
Claudio Olalla Marañón

The influence of the non-associative flow law on the bearing capacity of shallow foundations on rock masses is, in general, a subject that is not discussed in the field of rock mechanics. The calculation methods of bearing capacity usually do not define which flow law is adopted and, in some methods, the associative flow rule is assumed without knowing how that hypothesis influences the bearing capacity of the rock mass. In this paper, the study of the influence of the dilatancy angle on the bearing capacity of shallow foundations on rock masses is presented. The variation of the bearing capacity with the associative flow law and the non-associative flow law with zero dilatancy angle is studied using the finite difference method and by considering the influence of the self-weight of rock material. The calculations confirm the great influence of the flow law on the bearing capacity and a correction coefficient is proposed, which makes it possible to estimate the variation of the bearing capacity of the rock mass in terms of the function of the flow law for the hypothesis of weightless rock masses.


2012 ◽  
Vol 34 (4) ◽  
pp. 41-51 ◽  
Author(s):  
Adam Krasiński

Abstract Screw displacement pile technology is relatively new and is still being developed. A specific characteristic of those piles is their very considerable influence on soil properties during the installation, which renders classical bearing capacity calculation methods insufficient. Some methods for calculating the bearing capacity of screw displacement piles have already been presented in literature, for example, by Bustmante and Gianesselli [2], [3], Van Impe [17], [18], Maertens and Huybrechts [15], Ne Smith [16] as well as Basu and Prezzi [1]. This paper proposes a new method of calculating the bearing capacity of screw displacement piles in non-cohesive soil which is based on CPT results. It has been devised as a result of research project No. N N506 432936 [11], carried out in 2009-2011. At 6 experimental sites screw displacement pile static loading tests were carried out together with CPTU tests of the subsoil. The results allowed us to establish soil resistances along the shaft ts as well as under the pile base qb and their correlations to the CPT soil cone resistances qc. Two approaches, both adapted to the general guidelines of Eurocode 7 (EC7) [20], were proposed: a classical approach and the second approach with load transfer functions application.


Author(s):  
Ana Alencar ◽  
Rubén Galindo ◽  
Svetlana Melentijevic

AbstractThe presence of the groundwater level (GWL) at the rock mass may significantly affect the mechanical behavior, and consequently the bearing capacity. The water particularly modifies two aspects that influence the bearing capacity: the submerged unit weight and the overall geotechnical quality of the rock mass, because water circulation tends to clean and open the joints. This paper is a study of the influence groundwater level has on the ultimate bearing capacity of shallow foundations on the rock mass. The calculations were developed using the finite difference method. The numerical results included three possible locations of groundwater level: at the foundation level, at a depth equal to a quarter of the footing width from the foundation level, and inexistent location. The analysis was based on a sensitivity study with four parameters: foundation width, rock mass type (mi), uniaxial compressive strength, and geological strength index. Included in the analysis was the influence of the self-weight of the material on the bearing capacity and the critical depth where the GWL no longer affected the bearing capacity. Finally, a simple approximation of the solution estimated in this study is suggested for practical purposes.


2021 ◽  
Vol 14 (15) ◽  
Author(s):  
Mohammad Mahdi Hajitaheriha ◽  
Davood Akbarimehr ◽  
Amin Hasani Motlagh ◽  
Hossein Damerchilou

Author(s):  
M. A. Millán ◽  
R. Galindo ◽  
A. Alencar

AbstractCalculation of the bearing capacity of shallow foundations on rock masses is usually addressed either using empirical equations, analytical solutions, or numerical models. While the empirical laws are limited to the particular conditions and local geology of the data and the application of analytical solutions is complex and limited by its simplified assumptions, numerical models offer a reliable solution for the task but require more computational effort. This research presents an artificial neural network (ANN) solution to predict the bearing capacity due to general shear failure more simply and straightforwardly, obtained from FLAC numerical calculations based on the Hoek and Brown criterion, reproducing more realistic configurations than those offered by empirical or analytical solutions. The inputs included in the proposed ANN are rock type, uniaxial compressive strength, geological strength index, foundation width, dilatancy, bidimensional or axisymmetric problem, the roughness of the foundation-rock contact, and consideration or not of the self-weight of the rock mass. The predictions from the ANN model are in very good agreement with the numerical results, proving that it can be successfully employed to provide a very accurate assessment of the bearing capacity in a simpler and more accessible way than the existing methods.


Sign in / Sign up

Export Citation Format

Share Document