Hydraulic gradient similitude method for geotechnical modelling tests with emphasis on laterally loaded piles

Li Yan
A study has been undertaken to evaluate and apply the hydraulic gradient similitude method to geotechnical model testings. This method employs a high hydraulic gradient across granular soils to effectively increase self-weight stresses in the model. Testing principle and procedures are presented, and the factors affecting test results discussed. An apparatus (UBC-HGST) using this testing principle has been developed. Three applications are presented in which the hydraulic gradient similitude
more » ... dient similitude method is evaluated, and the existing concepts and methods of analysis for the problems studied are examined. In the footing tests, it is found that the scaling laws implied in the hydraulic gradient modelling test are satisfied, and are similar to those of the centrifuge modelling technique. Load-settlement curves are found to be similar to those in centrifuge tests. The test results illustrate the importance of the stress level in the load-settlement responses. Terzaghi's bearing capacity formula is compared with the observed bearing capacities under different stress levels. It is found that due to the stress level effects, the bearing capacity coefficient, Nγ, decreases linearly with footing width on the log-log scale which is in accordance with other model study and analytical results. In the downhole and crosshole seismic tests, results are used to evaluate the empirical equations that relate shear wave velocity and soil stresses in terms of field stress condition. It is found that although the various equations can predict the insitu shear wave velocity profile reasonably well, only the equation which is based on the significant stresses in the wave propagation and particle motion directions can predict the variation of velocity ratio between the downhole and SH crosshole tests. It is also found that the stress ratio has some effects on the downhole (or SV crosshole) tests, but not on the SH crosshole tests. This indicates that only the stress ratio in the plane of wave propagation is important to the shear [...]
doi:10.14288/1.0050461 fatcat:caouw7oplbcg7pin3pkpba3boi