Resistance of passive inclined anchors in cohesionless medium

Discussion: A generalized procedure for predicting optimal lower bound break-out factors of strip anchors

“…13. However, further experimental results in very dense sand (Murray & Geddes, 1989) suggest that the theoretical upper bound can underpredict experimental results although it can provide a reasonable assessment.…”

“…Figure 13 compares theoretical upper and lower bound solutions for a vertical strip anchor and experimental results. Of particular interest is the close correlation between the lower bound solutions of the Authors for a smooth strip anchor with 4 = 38" and the upper bound solutions of Murray & Geddes (1989) for a similar anchor in a cohesionless medium with 4 = 38.5". This suggests that the failure loading for a material obeying an associated flow rule is defined or closely bracketed.…”

The modelling of anchors using the material point method

“…Murray and Geddes [17] experimentally investigated the behaviour of anchors pulled at angles of 0-908 with the vertical. In this analysis, comparisons are made only to the case where the anchor was pulled at 458: The results are also compared to that of upper and lower bound analysis where the limit theorems of soil plasticity have been used.…”

“…The sand in the container was weighed to calculate the average unit weight g: Direct shear box tests on the sand yielded the friction angle f and cohesion c: A modified shear box was used to determine the interface friction m wall : No attempt has been made to determine the material stiffness E; Poisson's ratio n; the dilatancy angle c or the coefficient at rest K 0 : It has, however, been shown in the previous section that the stiffness has little effect on the limit load. Poisson's ratio is taken to be n ¼ 0:2 and Murray and Geddes [17] estimated the dilatancy angle to be within the range c ¼ 5-128: Table II Murray and Geddes [17] do not provide the load-displacement curves obtained from their experiments, but only give the ultimate loads for different embedded depths. The definition given by Rowe and Davis [9,10] is used to determine the ultimate capacity, given a loaddisplacement curve.…”

“…The upper and lower bound theorems enable the theoretical failure load of an idealized material to be bracketed. These theorems are based on the Mohr-Coulomb constitutive model [17]. Figure 7 shows the problem geometry.…”