An analytical method for developing a theoretical load-settlement curve for axially loaded piles in clay is presented. The method is based on the correlation of the ratio of load transfer to soil shear strength as a function of pile movement. The results of studies of field tests of instrumented piles and laboratory tests of small piles in clay are used to obtain the desired correlation. The correlation is presented in the form of a family of curves that are obtained when the ratios of load transfer to soil shear strength versus pile movement are plotted as a function of depth. The validity of the family of correlation curves is checked by comparing computed and actual load-settlement curves for some typical field tests. Results obtained by this method indicate that the method may be used effectively to determine load-carrying capacity for axially loaded piles in clay.

Closure to “Load Transfer for Axially Loaded Piles in Clay”

An elastic analysis is presented for the horizontal displacement and rotation of a laterally loaded pile group and the distribution of horizontal forces within the group. The interaction between two identical equally loaded piles is analyzed first, and the increases in displacement and rotation of the piles, in relation to the single pile values, are expressed in terms of interaction factors. Using these interaction factors, a method for calculating the displacement and rotation of a general pile group, based on the principle of superposition, is described. An examination of the behavior of square groups of piles reveals that the displacement, rotation, and load distribution in the group is largely influenced by the length-to-diameter ratio of the piles and the relative pile flexibility. It is also found that the displacement depends on the breadth of the group rather than the number of piles in the group. A reasonable measure of agreement is found between a limited number of reported measurements and theoretical predictions of group displacements.

Closure to “Behavior of Laterally Loaded Piles: II-Pile Groups”

https://www.cell.com/biophysj/pdf/S0006-3495(07)71585-0.pdf

Cell force microscopy on elastic layers of finite thickness

A simplified approach for settlement analysis of single pile and pile groups considering interaction between identical piles in multilayered soils

Resonant column tests of five fine-grained cohesionless soils showed the influence of capillary stresses on values of the low-amplitude shear modulus, G\do. This infuence was found to be greatest for the soils having the smallest effective grain diameter, D\d1\d0, and for the lowest external confining pressure, σ\do’. The maximum capillary influence developed at degrees of saturation between 5% and 20% for the soils tested. For the soil with the smallest D\d1\d0 (= 0.0024 mm) the maximum G\do was about two times G\do\d(\dd\dr\dy\d) for σ\do’ = 14.2 psi (98 kN/m). This latter pressure would correspond roughly to 20 ft. (6.1m) of overburden of incompletely saturated soils. Therefore, it would be expected that capillarity would affect insitu shear wave velocity measurements required for the dynamic design of shallow footings, runways, or other structures supported by soil near the ground surface. An empirical expression was developed which permits corrections of the value of G\do, measured at a particular degree of saturation, to the degree of saturation expected in prototype conditions.

Closure of "Capillary Effects on Dynamic Modulus of Sands and Silts"

Extended Sneddon and Muki solutions for multilayered elastic materials

Analytical layer-element solution to axisymmetric dynamic response of transversely isotropic multilayered half-space

A new numerical method for calculating the consolidation behavior of the stratified, transversely isotropic and poroelastic material is presented by combining the extended precise integration algorithm with the integral transformation techniques. Starting with the governing partial differential equations of a saturated medium with transversely isotropic skeleton and compressible fluid constituents, an ordinary differential matrix equation is deduced with the aid of a Laplace-Hankel transform. An extended precise integration method for internal loading situations is proposed to solve the ordinary differential matrix equation in the transformed domain, and the actual solution is recovered by a numerical inverse transformation. Numerical examples are also provided to prove the feasibility of this method.

Zhi Yong Ai

Papers

Extended Sneddon and Muki solutions for multilayered elastic materials

Analytical layer-element solution to axisymmetric dynamic response of transversely isotropic multilayered half-space

Extended precise integration method for consolidation of transversely isotropic poroelastic layered media

Analytical layer-element solution to axisymmetric consolidation of multilayered soils

Boundary element analysis of axially loaded piles embedded in a multi-layered soil