TY - JOUR
T1 - LDFE study of bottom boundary effect in foundation model tests
AU - Ullah, S.N.
AU - Hu, Yuxia
AU - White, David
AU - Stanier, Sam
PY - 2014/9
Y1 - 2014/9
N2 - © 2014, Thomas Telford Services Ltd. All rights reserved. Centrifuge model tests of deeply penetrating foundations have been widely used to assess the vertical bearing response, particularly in relation to the installation of spudcan foundations that support offshore drilling rigs. The potential influence of boundary effects owing to the proximity of these large foundations to the rigid base of the model container has not been previously addressed. In this study, large deformation finite-element (LDFE) analyses were conducted to assess the extent of the bottom boundary influence zone. Various foundation diameters were considered, with soil samples of sand overlying clay and uniform clay. The sand plug developed beneath the foundation is a major contributary factor to the boundary effect problem. The boundary effect is increased for sand over clay conditions, where a sand plug is entrapped beneath the foundation. The LDFE results were utilised to predict the thickness of the entrapped sand plug for different geometry and soil strength conditions. The results are distilled into a simple relationship that can be used to ascertain the bottom boundary influence zone when planning physical model tests and reinterpreting previous studies. The boundary influence zone predicted by the LDFE analysis agreed well with a corresponding centrifuge test.
AB - © 2014, Thomas Telford Services Ltd. All rights reserved. Centrifuge model tests of deeply penetrating foundations have been widely used to assess the vertical bearing response, particularly in relation to the installation of spudcan foundations that support offshore drilling rigs. The potential influence of boundary effects owing to the proximity of these large foundations to the rigid base of the model container has not been previously addressed. In this study, large deformation finite-element (LDFE) analyses were conducted to assess the extent of the bottom boundary influence zone. Various foundation diameters were considered, with soil samples of sand overlying clay and uniform clay. The sand plug developed beneath the foundation is a major contributary factor to the boundary effect problem. The boundary effect is increased for sand over clay conditions, where a sand plug is entrapped beneath the foundation. The LDFE results were utilised to predict the thickness of the entrapped sand plug for different geometry and soil strength conditions. The results are distilled into a simple relationship that can be used to ascertain the bottom boundary influence zone when planning physical model tests and reinterpreting previous studies. The boundary influence zone predicted by the LDFE analysis agreed well with a corresponding centrifuge test.
U2 - 10.1680/ijpmg.14.00004
DO - 10.1680/ijpmg.14.00004
M3 - Article
VL - 14
SP - 80
EP - 87
JO - The International Journal of Physical Modelling in Geotechnics
JF - The International Journal of Physical Modelling in Geotechnics
SN - 1346-213X
IS - 3
ER -