S.C. Yen

The bearing-capacity of a strip foundation on geogrid-reinforced sand

Abstract Laboratory-model test results for the bearing capacity of a strip foundation supported by a sand layer reinforced with layers of geogrid are presented. Based on the present model test results, the bearing-capacity ratio with respect to the ultimate bearing capacity, and at levels of limited settlement of the foundation, has been determined. For practical design purposes, it appears that the bearing-capacity ratio at limited levels of settlement is about 67–70% of the bearing-capacity ratio calculated on the basis of the ultimate bearing capacity.

FOUNDATION ON STRONG SAND UNDERLAIN BY WEAK CLAY WITH GEOGRID AT THE INTERFACE

Abstract A number of laboratory model test results for the ultimate bearing capacity of a surface strip foundation supported by a strong sand layer of limited thickness underlain by a weak clay with a layer of geogrid at the sand-clay interface has been presented. The tests were conducted at one relative density of compaction of sand and one undrained shear strength of clay. Two types of geogrid were used. Based on the model test results presented, it appears that the optimum height of the strong sand layer should be about two-thirds that of the foundation width for obtaining the maximum benefit from the geogrid reinforcement.

A laboratory investigation into the settlement of a foundation on geogrid-reinforced sand due to cyclic load

SummaryLaboratory model test results for permanent settlement of a shallow square foundation supported by geogrid-reinforced sand and subjected to cyclic loading are presented. During the application of the cyclic load, the foundation was subjected to a sustained static load. Tests were conducted with only one type of geogrid and at one relative density of compaction of sand. Based on the model test results, the nature of variation of the permanent settlement of the foundation with the intensity of the static loading and the amplitude of the cyclic load intensity are presented in a non-dimensional form.

Cyclic load-induced settlement of a square foundation on geogrid-reinforced sand

Abstract The permanent settlement of a square model foundation supported by geogrid-reinforced sand and subjected to cyclic loading has been evaluated. The foundation was initially subjected to an allowable static load and the cyclic load was superimposed on it. For a given static allowable load, the ultimate permanent settlement increases with the increase of the amplitude of the cyclic load. The results indicate that the ultimate permanent settlement is markedly reduced due to geogrid reinforcement.

Interference effect of two closely-spaced shallow strip foundations on geogrid-reinforced sand

SummaryGeotextiles and geogrids are now being used extensively in many civil engineering construction works. This study presents some laboratory model test results for the ultimate bearing capacity of an isolated, and two closely-spaced, strip foundations resting on unreinforced sand, and sand reinforced with layers of geogrid. Based on the model test results, the variation of the group efficiency with the centre-to-centre spacing of the foundation has been determined.

Ultimate uplift capacity of model rigid metal piles in clay

SummaryLaboratory model test results for estimation of the ultimate uplift capacity of rigid metal piles embedded in a compacted near-saturated clayey soil are presented. The length-diameter ratio of the piles was varied from 10 to 15. The direction of the uplift load on the pile was varied from 0 to 50°. Based on the present test results and the results of existing model studies, an empirical relationship for estimating the pile uplift capacity has been presented.