Plate‐loading tests were carried out on very dense calcareous sand for the construction of the new telecommunications center complex in downtown Kuwait City. The tests were conducted at the foundation level, which was located 18 m below the original ground level. Circular plates 0.3 m, 0.61 m, and 1.28 m in diameter, and a ring plate of 1.28 m outside and 0.68 m inside diameter were employed. The tests were intended to provide reliable soil modulus values for the estimation of the settlement of a 55‐m diameter ring‐shaped raft of the 370‐m tall antenna tower. Several factors affecting settlement were examined. These include soaking or ground wetting, the size of the loaded area, and load cycling or repetition. The load‐settlement response of the ring plates and the full plates are compared.

Conditions for plastic localization, in terms of the possibility for discontinuous bifurcations of the incremental strain rate field, are given for the MRS‐Lade model. The susceptibility to bifurcation is examined along various loading paths for the selected medium dense sand. It is shown that the stress states that are achieved in the conventional triaxial compression (CTC) test are the least susceptible to bifurcation, since there will be no possibility for bifurcation throughout the entire loading history (including hardening and softening regions). Contrasting this behavior, plane strain states (PSA and PSP) admit a possibility for bifurcation already in the hardening regime. Consequently, it is expected that accurate predictions of the global load‐displacement response for specimens loaded under plane strain conditions cannot be obtained at the constitutive level, where it is assumed that the state of deformation is homogeneous.

Field and laboratory observations of seismic settlements of shallow foundations on granular soils that are not attributable to changes in density or liquefaction are explained in terms of seismic degradation of bearing capacity. Limit analysis using a Coulomb‐type mechanism including inertial forces in the soil and on the footing gives expressions for seismic bearing capacity factors that are directly related to their static counterparts. Comparison of the two depicts clearly the rapid deterioration of the overall foundation capacity with increasing acceleration. Such periodic inertial fluidization causes finite settlements that are possible even in moderate earthquakes. Reduction in foundation capacity is due to both the seismic degradation of soil strength and the lateral inertial forces transmitted by shear to the foundation through the structure and any surcharge. A straightforward sliding‐block procedure with examples is also presented for computing these settlements due to loss of bearing capacity for short time periods. This approach also leads to a design procedure for footings based on limiting seismic settlements to a prescribed value.

This paper presents a theoretical model for the analysis of the axial response of tapered piles in cohesive frictional ground. The operating characteristics of tapered cylindrical piles are identified on the basis of experimental observations. In contrast to cylindrical piles, the side resistance of tapered piles continues to increase with the axial deformation because of the additional radial expansion of the ground caused by the tapered pile wall. A simplified theoretical model applicable to piles with small taper angles is developed for the analysis of the response of these piles. The application of the model to a field pile test indicates that it is very effective in predicting the side resistance development of tapered piles. A limited parametric study indicates that in many practical situations tapered piles offer a design option that is more economical than conventional uniform cross‐section piles.

Despite recent advances made in the wave‐equation‐based approach for pile‐driving control, at the time of writing, the dynamic formulas, such as the Engineering News Record (ENR) formula and its various modified versions are still widely used. One of the major reasons for the poor performance of the dynamic formula method, besides its obvious simplifications in treating complicated wave propagation phenomenon during pile driving, is the uncertainties about the energy transferred to the pile during each hammer blow. Assuming that energy input from the pile hammer can be determined, an improved dynamic method is developed for estimation of shaft resistances and their distributions of an impact‐driven pile. The method is cast within the principle of energy balance, with consideration of both elastic energy and plastic irreversible work. An incremental and forwardmarching solution algorithm is developed to partially compensate for the negligence of loading/unloading behavior when complex tension and compression wave forms travel through the pile. A wave‐equation‐based numerical program is used in performing a series of parametric studies to identify the effect of shaft‐resistance distributions and to generate engineering correlations between blow count and pilepenetration conditions (maximum pile velocity and acceleration due to each hammer impact). A simple microcomputer‐based, user‐friendly computer program is developed for field application. Verification of the developed method for both prototype pile driving and dynamic small‐rod penetration is provided by a favorable comparison between the results of the proposed method and those calculated from the so‐called CAPWAPC procedure, based on the measured high‐strain test data.

One of the main objectives of the present paper and its companion, part II, is to develop an integrated approach in which various factors relevant to the cyclic behavior of piles can be simulated in a unified manner. They include fundamental constitutive models for cyclic loading, appropriate laboratory tests, determination of material constants, validation of the model, and field verification. Development and verification of the constitutive model are described in part I. Here the hierarchical single surface (HiSS) plasticity‐based concept is modified to allow for the cyclic response of a clay that occurs at Sabine Pass, Texas, where the field pile load tests were performed. The new series of Δ^* models allows for hardening, normal consolidation and overconsolidation, general stress paths, and fluid pressures. Special procedures are developed to identify and to determine parameters for the models. Triaxial tests performed on undisturbed specimens of Sabine clay are used to find the parameters. The model is then validated by comparing predictions with laboratory observations. Verifications of field pile‐load tests using the model in a finite‐element procedure including simulation of various stages such as in situ stress, driving, consolidation, tension, and cyclic load tests are presented in part II.

Development and validation of the hierarchical single surface ${\Delta }_0^{*}$ model for cohesive soils are described in a companion paper, part I. The present paper, part II, first describes the details of the simulation and verification of various stages in the field behavior of piles, e.g. in situ stresses, driving, consolidation, tension tests, and the final cyclic loadings. Undisturbed samples were obtained for testing of cylindrical and cubical specimens, the latter involved design and fabrication of a square, $13\times 13\times 13\mathrm{cm}(5\times 5\times 5\mathrm{in}\text{.})$ sampler. Field measurements were obtained in terms of stresses, strains, and pore‐water pressures for various stages. The constitutive model (part I) is introduced in a general finite‐element (FE) procedure that allows dynamic analysis of porous soil media. The FE procedure is used to back‐predict the field behavior. It is found that the numerical procedure provides very good predictions of the measured responses. It is felt that the proposed unified (parts I and II) procedure can provide an excellent tool for a wide range of dynamic soil‐structure interaction problems.

It had been reported, through observation of actual field installations, that the inclusion of tensile reinforcement in the approach fill behind bridge abutments can effectively reduce approach fill settlement, and hence reduce the “bump” that may otherwise be experienced at both ends of the bridge. This study was undertaken to investigate, by the finite element method, the effectiveness of placing both tensile‐reinforcement sheets in the approach fill, and a “collapsible” inclusion between the reinforced fill and abutment in reducing bridge‐approach settlement. Confidence in the finite element analysis procedure was gained by comparing analytical results with the measured response of two controlled full‐scale bridge‐approach settlement tests; one with a geogrid reinforcement and the other without any reinforcement. Two parametric studies were then conducted. The first study examined the mechanism of tensile reinforcement for alleviating bridge‐approach settlement under different backfill, foundation, and reinforcement conditions. The second study examined the effectiveness of using both tensile reinforcement and a collapsible inclusion to reduce approach‐fill settlement, under different reinforcement stiffnesses and surcharge pressures. The results of the two studies are discussed.

The effect of varying percentages of large aggregate on the maximum dry density and optimum water content of clay is investigated through a series of laboratory compaction tests. Rock content (material retained on the No. 4 sieve) was varied from 0% to about 60% in the laboratory tests. The compaction tests are performed primarily using ASTM D698 method D, with replacement for oversized aggregate, i.e., the “scalp‐and‐replace” method. The maximum dry density obtained from ASTM D698 method D is compared with the maximum dry density estimated from rock correction equations in ASTM method 4718, U.S. Bureau of Reclamation method 5515‐89, and American Association of State Highway and Transportation Officials procedure T224. The optimum water content obtained from ASTM D698 method D is compared to the estimated optimum water content obtained from rock correction equations in ASTM method 4718. The data presented in this paper show that when soil fines are clayey, very significant differences in maximum dry density are obtained using scalp‐and‐replace procedures compared with the rock correction equations. The potential impact of these differences on construction compaction control are addressed.

The stiffness method originally proposed by Kausel and Roesset in 1981 for the analysis of wave propagation problems is used here to determine the deformations of horizontally layered systems subjected to static loads under plane‐strain conditions. Comparisons carried out by the writers have proved that this approach provides accurate results and constitutes an effective alternative to the use of other numerical techniques such as finite element or boundary element methods, which are significantly more costly and time‐consuming. In particular, the procedure is employed to investigate how the inclusion of a soft or stiff layer, placed at various depths within a uniform soil deposit, can affect the settlement of a footing.

There are many onshore and offshore situations where the lateral cyclic loading may affect both the pullout and lateral capacity of pile anchors. In this paper, an attempt has been made to study the effect of lateral cyclic loading on pullout capacity of rigid piles in clayey soil through an experimental investigation carried out on model piles. It is found that the reduction in the pullout capacity depends upon lateral deflection of the pile during cyclic loading and on its $L/d$ value. However, if the ratio of lateral cyclic load/static lateral capacity is kept below a value of 0.3–0.4, the lateral deflection of the pile will be less than 0.025 diameters to 0.03 diameters and hence, there will be no reduction in capacity.

A correlation between one‐dimensional unrestrained swell and swelling pressure is presented. The tested soils were from several projects located in Southern California. The swelling pressure tests and the unrestrained swell tests were performed on relatively undisturbed samples of the near‐surface soils at the in‐place moisture content and density. The specimens for a given set of swelling pressure test and the unrestrained swell test were taken from the same field sample. The unrestrained swell tests were performed under 1 psi (6.9 KPa) pressure. The presented correlation could be useful for preliminary estimation of swell pressure if the free swell is known and vise versa.

A series of tests were carried out on instrumented model piles to investigate the effect of interaction on the axial and lateral responses of piles in clay. The effect of lateral loading proved to be significant on the axial pile response, while the effects of axial loading on the lateral pile response were rather limited. Lateral loads increased considerably the axial displacement of the pile head. The amount of this increase depended on the value of the applied lateral load and on the level of the axial load. At low load levels where the soil behavior is linearly elastic, the increase in pile settlement due to a lateral load is very small. The explanation of these interaction effects was attempted through a nonlinear finite‐element analysis, in which the yielded zone created, in the soil, by the combined axial and lateral loading is larger than that developed by pure axial loads.