Analyses of load tests on 100 instrumented bored piles in different weathering grades of different tropical geological formations of peninsular Malaysia enabled correlations of ultimate shaft and base resistance with standard penetration test (SPT) results and unconfined compression strengths. The data also enabled development of shaft resistance (t–z) and base resistance (q–w) models that are related to SPT, unconfined compressive strength and rock types. The t–z models can be used for strain softening and strain hardening while the q–w models are for strain hardening and stiffening behaviour. The models thus developed were applied for analysis of 35 piles in the database that were loaded until the load–settlement curves were significantly non-linear. Most of the analyses resulted in a reasonable match with the measured load–settlement and load-transfer curves up to 1.5 times the pile working load, regardless of whether the q–w function was strain hardening or stiffening. Accurate matching with measured load–settlement and load-transfer curves for 1.5–3 times working load was conditional on the correct choice of the q–w function. The models were further tested against 27 published load test results from across the world.

In finite element modelling of laterally loaded pile or pile subjected to soil movement, normal stiffness (Kn) of pile-soil interface is required. However, the correlation of normal stiffness to soil stiffness is not widely available. This paper shows the results of the investigation of the normal stiffness by simulating the renowned laterally loaded pile test in Houston (in clay medium) and Arkansas (in sand medium). Series of parametric studies using 3D finite element program were carried by varying the ratio of normal stiffness to soil Young's modulus at reference level. By matching pile lateral deflection and bending moment of the pile. This study suggested that a ratio of 10 ~ 100 is acceptable for pile in clay domain while a ratio of 1 ~ 10 is acceptable for pile in sand domain. The study also found that Mohr Coulomb model fails to model the response of laterally loaded pile. By using an appropriate normal stiffness, the ultimate lateral load of the pile can be predicted by using 3D finite element program.

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