Evaluation of earthquake resistance of deep foundations of bridge supports, taking into account the interaction with the adjacent soil mass

1981 ◽  
Vol 18 (2) ◽  
pp. 66-70
Author(s):  
A. A. Nikitin ◽  
O. D. Tananaiko ◽  
A. M. Uzdin ◽  
M. A. Shvarts ◽  
S. A. Shul'man
Keyword(s):  
Soil Mass ◽  
Earthquake Resistance ◽  
Deep Foundations ◽  
Adjacent Soil

Failure Mechanisms of Pipelines Subjected to Loss of Support Under Deep Burial Conditions

2004 ◽  
Author(s):  
Yuri D. Costa ◽  
Jorge G. Zornberg ◽  
Benedito S. Bueno ◽  
Carina L. Costa
Keyword(s):  
Vertical Section ◽  
Failure Mechanisms ◽  
Soil Mass ◽  
Experimental Program ◽  
Rigid Base ◽  
Failure Patterns ◽  
Slip Surfaces ◽  
Deep Burial ◽  
Flexible Pipes ◽  
Adjacent Soil

This paper investigates the failure mechanisms of pipelines subjected to a localized loss of support. An experimental program was conducted, which consisted of a series of four centrifuge model tests containing an aluminum tube embedded in a pure dry sand backfill that was placed over an underlying rectangular rigid base moving downwards during the test. All models were built taking advantage of the longitudinal symmetry of the problem. The prototype pipe had a diameter (D) of 1.1 m and a soil cover height of about 5 D, characterizing deep burial conditions. Failure patterns were observed within a vertical section comprising the central axis of the pipe and also in four distinct vertical transverse sections along the length of the pipe in the region of ground loss. The influence of pipe stiffness and backfill density on the behavior of the system was assessed. The transverse sections showed fully developed slip surfaces starting in the vicinity of the edge of the void towards the adjacent soil mass. The mode of failure of the flexible pipes took the form of a severe deformation at the region of the shoulder and a reversal of curvature at the invert due to over-deflection. This situation was more critical in the central section. The damage experienced by the flexible pipes was noticeably more pronounced when using the looser backfill, whereas only negligible deflections were observed when using the denser backfill. The experimental results were compared with analytical predictions, which showed to be highly unconservative for the case loose backfill.

scholarly journals Analysis of Driven Piles Using Local and Non-Local Models

2020 ◽  
Author(s):  
Nicolas Sau ◽  
José Medina-Mendoza ◽  
Antonia López-Higuera
Keyword(s):  
Finite Element ◽  
Soil Mechanics ◽  
Element Model ◽  
Soil Mass ◽  
Deep Foundations ◽  
Local Models ◽  
Driven Piles ◽  
Peridynamic Model ◽  
High Gradients ◽  
Non Local

There exists a great potential for application in soil mechanics with the use of mechanistic models such as the finite element model, and other non-local models, such as the peridynamic model, since the soil mass can be modelled as a group of particles that interact with each other. In this work, we determine the bearing capacity of deep foundations where stresses are transmitted to deep deposits, which generally present better characteristics in terms of compressibility and shear strength. One of the main elements are driven piles, which must be previously designed, made and tested before their final use. In this work, a comparison with different methods is presented. The finite element method and the peridynamic model are used. Because the effect of consolidation was not taken into account, in these examples, the assumption is made that the structures are cemented in inert soil. Likewise, it is assumed that the water table has no influence on the simulations. Failure envelopes were observed where bonds between particles present high gradients of deformation and fracture. Bearing capacities were estimated and compared with those obtained from the Terzaghi and Meyerhof methods.

Geotechnical resistance factors for ultimate limit state design of deep foundations in frictional soils

2011 ◽  
Vol 48 (11) ◽  
pp. 1742-1756 ◽  
Author(s):  
Gordon A. Fenton ◽  
Mehrangiz Naghibi
Keyword(s):  
Limit State ◽  
Friction Angle ◽  
Soil Mass ◽  
Ultimate Limit State ◽  
Deep Foundations ◽  
Resistance Factors ◽  
Limit State Design ◽  
Ultimate Limit State Design ◽  
Ultimate Limit ◽  
Frictional Soils

This paper investigates the probabilistic nature of ultimate limit state failures of deep foundations in purely frictional soils (e.g., sands). In so doing, the theory required to predict both the probability of ultimate limit state failure and the resistance factors needed to avoid this limit state are proposed. The proposed resistance factors are functions of site understanding and failure consequence, and the theory leading to these resistance factors is validated via Monte Carlo simulation of a two-dimensional spatially variable random field. In both the theory and the simulation, a pile is assumed to be placed vertically at a certain position in the soil mass, and the soil is sampled at various distances from the pile to come up with characteristic soil properties (namely friction angle) for use in the pile design. Agreement between theory and simulation is found to be very good. The theoretical model is then employed to determine upper bound geotechnical resistance factors, which can be used to complement current ultimate limit state design code calibration efforts. An example of such a calibration is presented.

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