Static behaviour of model friction piles

377A load test procedures, and test results are presented. Benefits gained from increasing pile surface roughness and use of backfill are identified. 936351 Behaviour of instrumented test piles under horizontal loading (In French) Frank, R; Zervogiannis, H; Christoulas, S; Papadopoulos, V; Kalteziotis, N A Can Geoteeh J V30, N1, Feb 1993, PI-ll Two 31.7m long, 0.75m diameter bored piles, one postgrouted, were subject to horizontal loads in order to obtain design information for pier foundations of a cable stayed bridge. Axial loading tests had previously been carried out. The deformed shape of the piles and bending moments were recorded. Results were used to check various calculation methods using p-y reaction curves for cohesionless soils: API method, Menard pressuremeter method, and SPT method (Christoulas). These tests show simple site measurements can give interesting results on actual behaviour of horizontally loaded piles. 936352 Field pile load tests in saline permafrost. II. Analysis of results Biggar, K W; Sego, D C Can Geotech J V30, N1, Feb 1993, P46-59 Results of load testing of 14 piles in saline permafrost, as described in a companion paper, are analysed. Load distributions along the piles were evaluated from strain gauge data, and time dependent behaviour under constant load and performance of grout as a backfill material analysed. The grout cured adequately, such that failure was by anchor yield or in the frozen soil. A nearly uniform load distribution was found for smooth piles, but addition of lugs caused great nonuniformity. Time dependent behaviour of piles without lugs can be described by a power law relation. 936353 Cyclic analysis of axially loaded piles in calcareous soils Lee, C Y; Poulos, H G Can Geotech J V30, N1, Feb 1993, P82-95 A simple, nonlinear (modified Ramberg-Osgood) pile-soil interface model is incorporated into a modified boundary element analysis for behaviour of piles in calcareous soils. Degradation models of both pile friction and cyclic secant soil modulus are proposed. Parametric solutions are presented which examine the overall characteristics of axial response determined from the analysis. Theoretical predictions are compared to laboratory and field test data and the comparisons used to examine the suitability of alternative nonlinear analyses. 936354 Effects of cap thickness and pile inclination on the response of a pile group foundation by a three-dimensional nonlinear finite element analysis Zaman, M M; Najjar, Y M; Muqtadir, A Comput Geotech V15, N2, 1993, P65-86 An incremental-iterative finite element procedure is used to analyse the behaviour of a pile foundation subject to arbitrary 3D loading. A generalised plasticity model is used to represent the soil medium. Bending moments and shear forces on the piles and cap are evaluated using an algorithm based on interpolation of nodal displacements and finite difference approximation of the displacement field. Parametric analysis is used to investigate effects of pile inclination and pile cap thickness on distribution of moments and forces amongst the piles.

936355 Creep response of laterally loaded piles in ice and permafrost Puswewala, U G A; Rajapakse, R K N D; Domaschuk, L; Shields, D H Geotechnique V43, N2, June 1993, P223-240 A time-incremental finite element code, modelling the pile as a beam supported on a spring-dashpot system, has been developed to describe response of laterally loaded piles in ice or permafrost. Appropriate spring and dashpot parameters were obtained from analysis of laboratory tests on laterally loaded rigid rods in ice cores. Behaviour of floating laterally loaded piles in ice predicted using this model is in good agreement with results of a rigorous 3D continuum analysis, suggesting the code developed is a useful practical design tool. 936356 Stability of a rigid column with a non-linear restraint. Technical note Lancelotta, R Geoteelmique 1143, N2, June 1993, P331-332 Stability of equilibrium of slender structures is examined using the analogue of a rigid column connected at its base to a rotational spring whose response (the resisting moment) can be described using a nonlinear law. Stability is evaluated as a function of angle of tilt. Safety of the Leaning Tower of Pisa and a possible safety measure using sub-horizontal tendons are discussed as an example. 936357 Bearing-capacity of a strip foundation on geogrid-reinforced sand Khing, K H; Das, B M; Purl, V K; Cook, E E; Yen, S C Geotext Geomem V12, N4, 1993, P351-361 Laboratory model loading tests were carried out using a rough bottomed foundation resting on fine uniform silica sand containing layers of geogrid. Influence of number of reinforcing layers and of relative depth of first layer and relative length of reinforcement with respect to foundation dimensions (for set number of layers) have been examined. Results indicate that bearing capacity ratio at limited levels of settlement is about 70% of that calculated on the basis of ultimate bearing capacity. 936358 Static behaviour of model friction piles Rojas, E Ground Engng 1/26, N4, May 1993, P26-30 Preboring reduces ground heave and displacement and facilitates driving of friction piles in clayey ground. Common analytical methods for friction piles do not take into account preboring diameter or method of construction. Shape of a footing is also known to affect bearing capacity. To examine these factors, model tests were carried out with circular, square, rectangular, triangular, and hexagonal piles constructed with and without preboring. Effects of shape and prebored area on bearing capacity are described and discussed. 936359 Settlement of circular and ring plates in very dense calcareous sands AI-Sanad, H A; Ismael, N F; Brenner, R P J Geoteeh Engng Div ASCE VlI9, N4, April 1993, P622-638 Plate loading tests carried out prior to the construction of a 370m tall antenna tower in Kuwait City are reported. The tests were conducted at foundation level, some 18m below original ground level. Circular plates of diameter 0.3m, 0.61m, and

© 1993 Pergamon Press Ltd. Reproduction not permitted