详情

原文传递 Pile Designs Based on Cone Penetration Test Results

题名：	Pile Designs Based on Cone Penetration Test Results
作者：	Rodrigo Salgado and Junhwan Lee
关键词：	piles, sands, cone penetration test, bearing edacity, constitutive model, finite element analysis, limit states design, calibration chamber test
摘要：	The bearing capacity of piles consists of both base resistance and side resistance. The side resistance of piles is in most cases fully mobilized well before the maximum base resistance is reached. As the side resistance is mobilized early in the loading process, the determination of pile base resistance is a key element of pile design Static cone penetration is well related to the pile loading process, since it is performed quasi-statically and resembles a scaled-down pile load test border to take advantage of the CPT tor pile design, load-settlement curves of axially loaded piles bearing in sand were developed in terms of normalized base resistance (qb/qc) versus relative settlement (s/B). Although the limit slate design concept for pile design has been used mostly with respect to either s/B - 5S or s/B = 10% the normalized load-settlement curves obtained in this study allow determination of pile base resistance at any relative settlement level within the 0-20% range. The normalized base resistance for both non-displacement and displacement piles were addressed. border to order the pile base-settlement relationship , a 3-D non-linear elastic-plastic constitutive model was used in finite element analyses. The 3- D non-linear elastic-plastic constitutive model takes advantage of the intrinsic and stale soil variables that can be uniquely determined for a given soil type and condition A series of calibration chamber teats were modeled and analyzed using be finite element approach with the 3-D non-linear elastic-plastic stress-strain model. The predicted load-settlement curves showed good agreement with measured load-settlement curves. Calibration chamber size effects were also investigated for different relative densities and boundary conditions using the finite element analysis. The value of the normalized base resistance qb/qc, was no2 a constant, varying as a function of the relative denary, be confining stress, and be coefficient of lateral earth pressure at rest. The effect of relative density on the normalized base resistance qb/qc was meat significant, while that of the confining stress at be pile base level was small. At higher relative, the value of qb/qc was smaller (qb/qc =0.12-0.13 for DR=90%) than at lower relative densities (qb/qc,= 0.19-0.2 for DR=30%). The values of the normalized base resistance . qb/qc for displacement piles are higher than those for non-displacement piles, being Typically in the 0.15 - 0.25 range for s/B =5% and in the 0.22 – O35 range for s/B =10% The values of the normalized base resistance qb/qc, for silty sands are in be 0.12 - 0.17 range, depending on the relative density and be confining stress at be pile base level The confining stress is another important factor that influences be value of qb/qc, for silty sands. For lower relative density, the value of qb/qc decreases as the pile length increases while that for higher relative density increases. For effective use of CPT-based pile design methods in practice, the method proposed in this study and tome other existing methods reviewed in this study were coded in a FORTRAN DLL with a window-based interface This program can be used in practice to estimate pile load capacity for a variety of pile and soil conditions with relatively easy input and output of desired data.
报告类型：	科技报告