Data were taken during the lateral loading of two 24-in. diameter test piles installed at a site where the soils consisted of clean fine sand to silty fine sand. Two types of loading were employed, static loading and cyclic loading. The data were analyzed and families of curves were developed which showed the soil resistance p as a function of pile deflection y. With theoretical studies as a basis, a method was devised for predicting the family of p-y curves based on the properties of sand and pile dimension. Procedures are suggested or both static loading and cyclic loading. While there is some basis for the methods from theory, the behavior of sand around a laterally loaded pile does not yield to a completely rational analysis; therefore, a considerable amount of empiricism is involved in the recommendations. The procedure was employed for predicting p-y curves at the experimental sire and computed results are compared with experimental results. The agreement is good. Foreword This paper is a companion to the paper entitled, "Field Testing of Laterally Loaded Piles in Sand," by William R. Cox, Lymon C. Reese and Berry R. Grubbs. The research described in fund set up by the following oil companies: Amoco Production Company, Chevron Oil Field Research, Esso Production Research Company, Mobil Oil Corporation, and Shell Development Company. Shell Development Company was the operator of the project. Introduction There are a relatively small number of papers in the technical literature which give recommendations for predicting the behavior of the soil around the piles subjected to lateral loading. With regard to sand, such recommendations are made in two papers, Terzaghi1 and Parker and Reese.2 Terzaghi presents no experimental evidence for the parameters which he recommends; the paper by Parker and Reese is based on lateral load tests of small diameter piles. The method presented below is based on the results of full-scale tests of instrumented piles and should be a useful addition to the literature. The differential equation, Eq.1, for the problem of the laterally loaded pile is well known and its solution has been discussed by a number of authors. 3,4,5,6,7 (Mathematical Equation Available in Full Paper) It should be noted that Eq. 1 does not include a term to account for the effect of axial load on bending. If the axial load is sizable, Eq. 1 should be expanded. As indicated in the referenced papers, appropriate solutions can sometimes be obtained by the use of non-dimensional relationships. A more favorable approach is to write the differential equation in difference form and to obtain solutions by use of the digital computer. In the solution of the differential equation, appropriate boundary conditions must be selected at the top of the pile to insure that the equations of equilibrium and of compatibility are satisfied at the interface between the pile and the superstructure. The selection of the boundary conditions is a simple problem in some instances; for examples, where the superstructure is simply a continuation of the pile.

Two nominally 24-in. diameter piles, instrumented for measuring bending moments, were driven into stiff clay and subjected to lateral loading. A nominally 6-in. diameter pile was also instrumented for measuring bending moments. It was driven at the same site, loaded, pulled, redriven, and reloaded. Short-term static and cyclic loading was employed on both 24-in. diameter and 6-in. diameter piles. The water table was maintained a few inches above the ground surface during the testing program. The results of the tests were analyzed to obtain families of curves showing soil resistance p as a function of pile deflection y. Based on the experimental p-y curves and on theory for the behavior of soil, procedures for predicting p-y curves for stiff clay were developed. The procedures were used and predictions of pile behavior at the site were made. The predictions compared favorably with actual behavior. Foreword The research described in this paper was sponsored by Amoco Production Company, Chevron Oil Field Research, Exxon Production Research Company, Mobil Oil Corporation, and Shell Development Company. Shell Development Company was the operator of the project. Location of Test Site The field studies on which this paper is based were made at a location five miles to the northeast of Austin, Texas adjacent to US Highway 290. The surface soils in this area consist of stiff, preconsolidated clays of marine origins. These clays are referred to as the Taylor group and studies showed that unconfined compressive strengths of 2 to 10 tons/ sq ft were not uncommon in zones near the surface. These clays have a secondary structure, such as fissures, joints or slickensides, that was desirable because of the wide occurrence of this type of soil in nature. The secondary structure was expected to result in a less favorable behavior of the clay; therefore, a possibly critical soil condition could be investigated. Preparation of Test Site On December 15, 1966, a pit 45 ft wide by 50 ft long by 3 ft deep was excavated at the test site. A plan of the test area is shown in Fig. 1 with the locations of all soil borings and test piles. After the excavations was completed the pit was flooded with water to saturate the near surface clays and to simulate conditions that would exist in clays on the ocean floor. This initial inundation was done some five months before the installation of the first test piles and some six months before lateral loading of test piles. In April 1967, two soil borings, borings 5 and 6, were made to investigate the influence of some four months of ponding on the water content of the clay. These borings indicated an increase in water content with an accompanying decrease in shear strength for clays in the first few feet below the pit bottom. After borings 5 and 6, the pit was lowered an additional 2-1/2 ft. This additional excavation was done on April 21, 1967 and the pit was again inundated.

A series of field tests was made to develop criteria for the design of laterally loaded piles in sand under both static and cyclic loads. Two 24-in. diameter piles were instrumented with strain gages for measur~ng bending moment at points along the piles. The gages were calibrated by applying known moments and read ing the output of the gages.~ydraulic equipment was developed for applying both static and cyclic loads. A calibrated load cell, employing strain gages, was used for measuring lateralload, and linear-displacement transducers were used for measuring the deflection of the pile at two points above the ground surface. The output from the moment gages, from the load cell, and from the linear -displacement transducers was rec.orded with a high-speed digital system.A site was selected at Mustang Island, Texas,and two soil borings were taken. The instrumented piles, the reaction piles, and the loading apparatus were installed, and a comprehensive series of field tests was perforxned.

The most up-to-date method for the design of laterally loaded piles is to solve numerically the differential equation describing pile behavior. Iterative solutions are necessary since there is a nonlinear relationship between soil resistance and pile deflection. Curves giving soil resistance as a function of pile deflection, called p-y curves, have been the subject of research for a number of years. The development of p-y curves normally requires that a test be performed on an instrumented laterally loaded pile. A curve showing bending moment in the pile needs to be obtained for each of the applied loads. This curve can be differentiated twice to obtain soil resistance, and it can be integrated twice to obtain pile deflection. Cross plots of these values can be made at desired depths to obtain the p-y curves. This paper shows that nondimensional curves, developed from the numerical solutions of the differential equation, can be used to estimate p-y curves if only the following easily obtainable information is reported; pile properties, magnitude of the individual lateral loads, point of load application, deflection of the top of the pile, slope of the top of the pile, and condition of restraint (if any) at the top of the pile. Thus, there needs to be no instrumentation of the pile except above ground. The procedure is illustrated by applying it to a test reported in the literature.

Procedures· are developed for estimating geometry and load distribution in a chain connected from a floating object t·o a fixed anchor beneath the seabed. Previously published information on this subj ect has been restricted to a discussion of resistance of soil to movement of chain normal to the chain path. This paper expands the theory to include procedures for considering tangential resistance of soil to movement of the chain, the effective weight of chain in soil, and the general case of chain entering the s oil at an angle.The more rigorous treatment of chain behavior in s oil yields s:ril.allerToads on anchor s. These smaller loads could result in savings on installation costs for anchors. A parameter study is included to snow the influence of several variables on chain loads at the anchor.