Prediction of screw pile behaviour in alluvial soils

188A 933379 Prediction of screw pile behavionr in alluvial soils Abedin, M D Z; Safiullah, A M M Proc Ninth Asian Regional Conference on Soil Met&nits and Foundation Engineering, Bangkok, 9-13 December 1991 VI, P125-128. Publ Thailand." Southeast Asian Geotechnical Society, 1991 Equations to compute driving torque, uplift capacity, and displacement for multihelix screw piles are presented. Correlations are developed between driving torque and soil strength (linear) and between uplift load and displacement (loglinear). The parameters for these equations are statistically analysed using field data for piles in alluvium in Bangladesh. The equations may be used to predict required driving torque from simple strength parameters (or vice versa) and to estimate bearing capacity and displacement of screw piles. 933380 Applicability of prnctical formula for bearing capacity of day improved by SCP Terashi, M; Kitazume, M; Okada, H Proc International Comfereoce on Geotedmical EngiKering for Coastal Deaelopment, GEO-COAST'91, Yokalmma, 3-6 September 1991 P405-410. Publ Japan: Coastal Development Institute of Technology, 1991 Centrifuge model tests on a caisson founded on soft clay improved by sand compaction piles are described. Particular attention was paid to effects on bearing capacity of load inclination and preload, which reflect improvement of shear strength of the composite ground by reinforcement and consolidation respectively. Local failure of sand piles governs yielding of the ground in most cases of undrained loading. A simple analysis is presented to explain hearing capacity where replacement area ratio is low, which is validated by results of full scale field tests. 933381 Investigation, design and monitoring of concrete raft foandations on expansive soils: a case study of prelimin~V performance Strydom, J H; Pellissicr, J P Proc Tenth Regional Conference for Africa on Soil Mec&mics and Foumlation Eagioceriag and the TMrd lntermUiotud Conference on Tropical ant Residual Soils, Masern, 23-27 September 1991 V1, P401-408. Publ Rotterdam: A A Balkema, 1991 Initial experiments prior to a major housing development at a site of expansive residual soils are described. According to expected degree of heave, structures were founded on rafts of different stiffnesses. Articulated joints were used in the superstructure. Foundation movements, structural movement, and variation in soil moisture with depth have been monitored for over a year. Attempts are made to explain measured movements in terms of soil moisture variation. Visual assessment of the minor structural distress was also undertaken.

Dams and embankments See also: 933153 933382 Monolithic stability analysis of Ertan Arch Dim in complex rock formations Zhou Weiyan; Yang Ruoqiong; Yang Quiang Proc 7th I S R M InterutioMi Congress on Rock Meclumics, Aachen, 16-20 September 1991 VI, P827-831. Publ Rotterdam: A A Balkema, 1991 The Ertan Dam is a double arch structure in a deep, narrow valley. The abutments are of basalt containing several large faults, some irdilled, and three sets of nonorthogonal intersecting joints. Three dimensional finite element analysis (TFINE) has been carded out at stages from self-weight loading to failure. Opening of fissures and fracture propagation have been examined. Physical model tests of the dam were also carded out, with loads of up to 12x normal water load. Failure development and loads for the two approaches are in reasonable agreement. 933383 Embankment on soft organic soil using the weloadlng technique Carlsten, P Proc lOth European Coherence om Soil Meelumics aml Foundation ~ e r b t g , Florence, 26-30 May 1991 VI, P359362. Publ Rotterdam: A A Balkema, 1991 Preloading is often used to compact foundations for road embankments. The method requires good knowledge of the geotechnical parameters of the soils, and, as it takes much longer than piling or replacement, must be planned and executed at the early stages of a project. The calculation method for preloading treatment is outlined. Two examples of its application over peat and gyttja (organic mud) soils are presented. Observed and calculated settlements are compared. 933384 Stability of soft day improved with sand compaction piles under a fill Takemura, J; Tean, L B; Suemasa, N; Hirooka, A; Kimura, T Proc International Conference on Geoteclmical F.agineerin& for Coastal De~elopmeM, GEO-COAST'91, Yokakama, 3-6 September 1991 P399-404. Publ Japan: Coastal Development Institute of Technology, 1991 Sand compaction piles are widely used in Japan to improve soft alluvial embankment foundations. Centrifuge model tests have been carried out using a soft clay improved in the embankment toe area. The area ratio and width of the composite ground were varied. The embankment fill was added inflight in a number of lifts. The sand compaction piles prevented catastrophic failure accompanied by well defined slip surfaces. Improvement of the area under the embankment slope is sufficient for stability, with no further substantial improvement if this area is extended.

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