TY - RPRT
T1 - Investigation on the Effect of Drained Strength when Designing Sheet Pile Walls
AU - Iversen, Kirsten Malte
AU - Nielsen, Benjaminn Nordahl
AU - Augustesen, Anders Hust
PY - 2010
Y1 - 2010
N2 - Long sheet pile walls are constructed in the cities as an integrated part of deep excavations for e.g. parking lots, pumping stations, reservoirs, and cut and cover tunnels. To minimise costs, the strength of the soil needs to be determined in the best possible way. The drained strength of clay expressed by c and ϕ is often estimated as c 10% = 10%・cu, and found by estimations based on the soil describtion, respectively. However, due to possible slicken slides and tension cracks, c = 0 is used on the back side of the sheet pile wall. This reduces the strength significantly. A parametric study is made on the effective cohesion to investigate the influence of c when designing sheet pile walls. Aalborg Clay is used as a case material. The parametric study is made in both a commercial finite element program and by use of Brinch Hansen’s earth pressure theory. In both studies, the analyses are made based on soil pressures only. The finite element analyses show that the safety factors increase with increasing cohesion. The safety factor is defined as the ratio of the surface load applied on the back side to the surface load applied at failure. Brinch Hansen’s earth pressure theory indicates that the height, anchor force, and the maximum bending moment in the wall can be lowered significantly when the effective cohesion is increased above zero. However, as the cohesion increases, the drop in the moment levels off, which implies that the benefit obtained from investigations increasing the cohesion more than c10% is small.
AB - Long sheet pile walls are constructed in the cities as an integrated part of deep excavations for e.g. parking lots, pumping stations, reservoirs, and cut and cover tunnels. To minimise costs, the strength of the soil needs to be determined in the best possible way. The drained strength of clay expressed by c and ϕ is often estimated as c 10% = 10%・cu, and found by estimations based on the soil describtion, respectively. However, due to possible slicken slides and tension cracks, c = 0 is used on the back side of the sheet pile wall. This reduces the strength significantly. A parametric study is made on the effective cohesion to investigate the influence of c when designing sheet pile walls. Aalborg Clay is used as a case material. The parametric study is made in both a commercial finite element program and by use of Brinch Hansen’s earth pressure theory. In both studies, the analyses are made based on soil pressures only. The finite element analyses show that the safety factors increase with increasing cohesion. The safety factor is defined as the ratio of the surface load applied on the back side to the surface load applied at failure. Brinch Hansen’s earth pressure theory indicates that the height, anchor force, and the maximum bending moment in the wall can be lowered significantly when the effective cohesion is increased above zero. However, as the cohesion increases, the drop in the moment levels off, which implies that the benefit obtained from investigations increasing the cohesion more than c10% is small.
KW - Sheet Pile Walls
KW - Soil Strength
KW - Clay
KW - Cohesion
KW - Numerical Model
KW - Bending Moment
KW - PLAXIS
KW - Sheet Pile Walls
KW - Clay
KW - Numerical Model
KW - Bending Moment
KW - Cohesion
KW - Soil Strength
M3 - Report
T3 - DCE Technical reports
BT - Investigation on the Effect of Drained Strength when Designing Sheet Pile Walls
PB - Department of Civil Engineering, Aalborg University
CY - Aalborg
ER -