Experiments conducted with instrumented model pile segment probes at Harvey and Empire, Louisiana are summarized and the observed behavior interpreted. Correlations are developed for the time rate of strength gain and interim recommendations are given for construction of t-z curves (soil resistance versus axial pile displacement) for use in design. The methods are compared with existing pile test results.

Fourteen experiments were conducted at Empire, La. using instrumented pile simulation probes to measure lateral pressures and t-z behavior at various times and under a variety of loadings. Three of the fourteen were conducted at the same depth in parallel bore holes and enable comparisons of the effects of two diameters and two end conditions. A detailed presentation of the three sets of results leads to an improved understanding of the significant mechanisms and processes involved in the axial-load behavior of long offshore piles. Introduction Two types of instrumented probes have been developed to model segments of long flexible piles. The probes are instrumented to determine in situ the significant soil response parameters under a variety of static and cyclic loading conditions (Refs 1 and 2). The resulting data provide a basis for more rational and reliable axial pile design methods. Experiments have included consideration of the effects on axial pile capacity of diameter, wall thickness, and setup or consolidation time, plus the effects of displacement and load history, and cyclic degradation. In 1975 a series of tests on four 50-ft-long pipe piles 14 inches in diameter were performed at Empire, Louisiana for Chevron Oil Field Research Company (Refs 3 and 4). Test depths ranged from 115 to 360 ft. In April, 1984, fourteen experiments were performed with the instrumented model segment probes at the same site. Test depths ranged from 120 to 250 feet, covering the depths reported for Chevron's piles 1 and 2. Eight of the experiments were in a normally consolidated clay from 120 to 160 feet. The locations of the borings in which the experiments were performed are shown in Fig 1. Also shown are the locations of earlier work at the site, including the original pile tests by TERA, soil borings made by McClelland Engineers, proprietary CPT and pyrometer work done by Fugro Gulf, and experiments with the PLS probe done by the Massachusetts Institute of Technology (Ref 5). OBJECITVES The research program was originally proposed as a fundamental study of the response of a normally consolidated clay to a pile under a variety of loading conditions, including comparisons with the Chevron pile tests. The probes have been successfully deployed at the onshore and offshore sites of three instrumented large-scale pile load tests and at two onshore sites for which parallel large-diameter pile load test data are not available. The scope included examination of open and plugged end conditions, effects of diameter on setup and shear transfer, degradation under one-way and two-way cyclic loading, and the effects of loading rate on shear-displacement behavior

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ABSTRACfThree field experiments have been conducted in normally consolidated soft clay at Harvey, La. using instrumented 3inch diameter probes to simulate pile behavior under a variety of static and cyclic axial loadings. Lateral total pressure and pore pressure were observed and shear transfer versus pile displacement were recorded. The results represent the first phase of a comprehensive program to develop an improved basis for pile design. INTRODUCfIONAs a part of a comprehensive program of research into the behavior of friction piles in clay, in situ pile segment models, or probes, have been developed to measure total radial pressure, pore pressure, shear transfer, and relative pile-soil displacement during installation, consolidation, and static and cyclic axial loading.The experiments reported herein were the first of 47 experiments performed with the probes, which have included tests at the onshore sites of two large-diameter instrumented pile load tests, the offshore site of load tests on instrumented large-diameter driven and drilled-and-grouted piles, and three onshore sites where parallel large-diameter pile load tests are not available.Four of the six sites contain soft-to-stiff normally consolidated clays. At the four sites, a total of 42 experiments were performed, with load testing at times ranging from minutes to three months after installation. The data are believed to represent a sound basis for References and illustrations at end of paper 469 developing a fundamental understanding of pile-soil interaction and for developing reliable design procedures for the design of pile foundations subjected to static and cyclic axial loading. MElliODSThe pile segment models were developed at The Earth Technology Corporation (Refs 1 and 2). Two sizes, 3.00 and 1.72 inches in diameter, have been built and utilized in field tests at various locations.The 3-inch size permits investigation of various cutting shoes or end conditions and is the type employed for the tests reported in this paper.The features of the 3-inch probe and the three stages of installation are shown in Fig 1. The tool is impact-driven or jacked into the soil beyond the end of a drilled hole. The leading section is a tube which is long enough to simulate the effects of an open-end pile in the zone where the instrumented section comes to rest. Various wall thicknesses or a fully plugged condition can be utilized. At the slip joint shown at the left, the leading section is free to move one inch with respect to the instrumented section and the relative movement is indicated with an internal displacement transducer. After installation, the leading section serves as an anchor for accurate measurement of pile-sail displacement. Soil shear transfer is measured as the differential reaction between the two load cells. The pressure measurements aid in interpreting soil consolidation and set-up processes, plus porewater and structural changes during shear.Cyclic load testing is controlled by preset limits of either displacement or shear transfer. All m...