113_CEG 4012 Notes Fall 2011 CEG 4012 Notes Fall 2011

113_CEG 4012 Notes Fall 2011 CEG 4012 Notes Fall 2011 -...

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DF3 Insertion Methods: o Driving - dynamic, drop hammer typically air driven (big compressor) with heavy ram and low stroke « 5 tI), diesel hammer (one cylinder engine, compact, single- or double-acting) with lighter ram and higher stroke (6-9 til. diesel has higher impact velocity and force - increases driving stresses and pore pressures in soil (harder driving) o Jacking - quasi-static, low capacity piles, short, stiff piles, good in congested areas, less capacity than driven, suaU:r g0Q--displacement, need reaction, sheet piles o Vibratory- dynamic, rotating eccentric weights, hydraulic power pack, good for non-displacement piles, temporary structures, extraction, less capacity than hammer driven, difficult to estimate capacity, can damage structures with harmonic vibrations o JettinglPreaugering - use to penetrate denser soils and rock lenses without damage to pile, unreliable capacity if not followed by driving, potential damage to adjacent structures, may use to minimize driving vibrations
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Unformatted text preview: Estimating Single Pile Capacity in Axial Compression: (starting point, but seldom use just one) This is a complex soil-structure interaction problem. Insertion of the pile disturbs the soil and affects its strength. Capacity of the pile is affected by soil type, pile type, pile size and length, pile material, displacement and arching of soil around pile during installation, sensitivity of soil, overconsolidation, time, etc. Pile capacity calcutated by: 1. Static Analysis - side shear, toe bearing capacity 2. Pile driving formulae, wave equation (energy methods) 3. Field load tests - verify design, static, dynamic, "statnamic" P, P, P, P, I I , I I (0) ('J (oj P, (d) PtandU ~Betr Bere~antsev and Bishop, Hill and Reissner laky Varoshenko Mo" Caquot Meyerhof Vult Skemplon. Vanin, Buisman amI Gibson Terzaghi Assumed failure patterns under deep foundations. (From Vesic, 1967). (figure from Lambe & Whitman)...
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