Rational Wave Equation Model for Pile‐Driving Analysis

Lee, S. L.; Chow, Y. K.; Karunaratne, G. P.; Wong, Kelvin

doi:10.1061/(asce)0733-9410(1988)114:3(306)

Cited by 77 publications

(21 citation statements)

References 12 publications

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“…Additionally, the spring and radiation dashpot coefficients are valid for steady state, constant-amplitude motion. Lee et al (1988) proposed a model that is virtually identical to that by Randolph and Simons (1986) with the only difference being that slippage happens when the spring reaction becomes larger than τ sf , stat , at which point the radiation dashpot is deactivated. This approach is not as consistent with the mechanics of the problem and results in a discontinuity in the time history of the total reaction when the radiation dashpot is deactivated.…”

Section: Shaft Reaction Model Bymentioning

confidence: 99%

Section: Problem Statementmentioning

confidence: 99%

“…Lee et al (1988) collected the data of several experimental studies (Coyle and Gibson, 1970;Dayal and Allen, 1975;Dolwin et al, 1979;Heerema, 1979Heerema, ,1981Litkouhi and Poskitt, 1980) and found that the parameters m s and m b correlate relatively well with the shear strength parameters of the soil; the stronger the soil is, the smaller the m s and m b values are. Lee et al (1988) consider a value of 0.2 for both n s and n b , independently of the soil type. Based on Lee et al (1988), the following correlations can be established for sands, where φ is the sand peak friction angle in degrees.…”

Section: Selection Of Soil Viscosity Parametersmentioning

confidence: 99%

“…Lee et al (1988) consider a value of 0.2 for both n s and n b , independently of the soil type. Based on Lee et al (1988), the following correlations can be established for sands, where φ is the sand peak friction angle in degrees. Lee et al (1988) assume that the multiplier m s for the pile shaft in sands is negligible.…”

Section: Selection Of Soil Viscosity Parametersmentioning

confidence: 99%

“…In the course of the following decades, several improvements were made to the original work by Smith (e.g. Lowery et al 1969;Hirsch et al 1976; Rausche 1976, 1986;Simons and Randolph 1985;Lee et al 1988;Rausche et al 1994;Hussein et al 1995).Alternative techniques were also proposed for analyzing pile driving, such as finite element analysis (e.g. Coutinho et al 1988;Borja 1988;Nath 1990;Deeks 1992;Mabsout and Tassoulas 1994;Mabsout et al 1995;Liyanapathirana et al 2000;Masouleh and Fakharian 2007) or closed-form solutions (e.g.…”

mentioning

confidence: 99%

See 4 more Smart Citations

Assessment of Axially-Loaded Pile Dynmaic Design Methods and Review of INDOT Axially-Loaded Design Procedure

Loukidis¹,

Salgado²,

Abou-Jaoude³

2008

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IntroductionThe main goal of the present study is to make a comprehensive assessment of the existing methods for the dynamic analysis of pile driving, identify the shortcomings and propose improvements. A review of existing shaft and base soil reaction models used in dynamic pile analyses is done to evaluate their effectiveness and identify points that require improvement. Subsequently, we develop improved shaft and base reaction models for use in 1-D dynamic pile analysis. The proposed models are validated using experimental data recorded during driving of field piles and model piles. The procedures currently used by INDOT for the design of axially loaded piles are also examined. For this purpose, interviews were conducted with INDOT engineers and private geotechnical consultants involved in INDOT projects. FindingsThe interviews with INDOT engineers and consultants focused on the methods and procedures presently followed in deep foundation design projects. The methods and the computer software used by private consultants involved in INDOT projects for the design of axially loaded piles are consistent with those used by INDOT's geotechnical engineers. These methods and software follow FHWA guidelines and are in accordance with the standard practice in the U.S. Pile design is mostly based on Standard Penetration test (SPT) data and undrained shear strength measured in unconfined compression tests. Cone penetration tests are rarely performed, although both INDOT and private soil exploration companies have the necessary equipment. Pile drivability calculations and back-calculation of the pile capacity from dynamic test data are done using software that employs Smith-type soil reaction models. Pile driving monitoring and restrike tests are usually performed only in projects whose cost exceeds a certain limit. Static load tests are reserved mostly for research projects.The methods for estimating the unit shaft and base resistances currently used by geotechnical engineers (INDOT or private consultants) have been developed over twenty years ago and have a large empirical content. There has been significant progress regarding methods for the calculation of unit base and shaft resistances. Numerous improved methods that are grounded on the physics and mechanics governing the development of pile resistance have been developed by combining experimental data with analysis. In the case of clayey soils, the differences between the state-of-the-practice methods and the updated methods are not large. In contrast, the formulation of the new methods for piles in sands has important fundamental differences with respect to traditional methods. The new methods for the base resistance in sands use as input either the relative density or the cone resistance directly. The recently developed methods recognize the fact that the limit base resistance is almost equal to the cone penetration resistance and that the ultimate unit base resistance in sands is smaller than the limit unit base resistance. Notably, the equations for β adopted by...

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Section: Shaft Reaction Model Bymentioning

confidence: 99%

Section: Problem Statementmentioning

confidence: 99%

Section: Selection Of Soil Viscosity Parametersmentioning

confidence: 99%

Section: Selection Of Soil Viscosity Parametersmentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Assessment of Axially-Loaded Pile Dynmaic Design Methods and Review of INDOT Axially-Loaded Design Procedure

Loukidis¹,

Salgado²,

Abou-Jaoude³

2008

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Prediction of pile capacity from stress‐wave measurements: Some numerical aspects

Chow

Wong

Karunaratne

et al. 1988

Num Anal Meth Geomechanics

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SUMMARYThe analysis of measured stress waves for the prediction of static pile capacity is described. The usual method of using the measured velocity record as the input boundary condition in a wave equation analysis with a finite element model, if not properly implemented, can lead to significant numerical errors. An alternative scheme using an accurate prescribed displacement procedure with the measured displacement record (obtained from the integration of the velocity) is proposed, and is shown to be very efficient. These aspects of the numerical modelling procedure are illustrated by a case study. INTRODUCTIONDevelopments in electronics technology have made it possible to make reliable measurements of force and acceleration near the pile head during impact driving, and a number of proprietory systems have been developed for this purpose. The record of force or velocity (integrated from the acceleration) is used as the input boundary condition in a wave equation model, and the other quantity is computed. The computed values are then compared with the measured values. The analysis may then be repeated by adjusting the soil parameters, with due consideration for the mechanics of stress-wave theory, until no further improvement can be made. The time taken to achieve a reasonable match depends very much on the ability of the operator. Experience with piles in the same site or piles with similar stress-wave profiles can help to reduce analysis time significantly. When a reasonable match is obtained, the soil parameters used in the wave equation model are assumed to be reasonably close to the actual values along the pile shaft and at the pile toe. It is always a good practice to perform a reverse analysis. For example, if the measured force trace was used as an input boundary for the velocity match, then a satisfactory force match should be obtained when the measured velocity trace is used as the input boundary. If the reverse analysis does not result in a reasonable match, then the measured traces may not be compatible, indicating that one or both of the measurements may have significant errors.The use of the measured stress waves as boundary conditions in the analysis eliminates the uncertainty associated with the energy transferred to the pile by the driving system. It is found that this approach gives reasonably good predictions of static pile capacity. One of the earliest papers to describe this procedure was by Rausche et al.,l from which further details may be obtained.The field sampling time for the velocity and force traces using a pile driving analyser is 0.1 ms, and this is the timestep which should be used in wave equation analysis so that all the information in the measured signals may be assimilated. A larger timestep may cause important signals to be

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Modelling of vibratory pile driving in sand

Wong¹,

O’Neill²,

Vipulanandan³

1992

Num Anal Meth Geomechanics

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SUMMARYA model for vibro-driving of rigid piles in sand is proposed incorporating the interaction of the vibrator-pile-soil system. The vibro-driver force and the non-linear soil resistance (dynamicf-w and q-w relationships) have been quantified in terms of in situ stress, relative density and particle size. The influence of relative density (0.65 and 0.90), particle size (effective grain size of 0.2 mm and 1.2 mm) and in situ stress (up to 20 psi) on the vibro-driving of a closed-ended pipe pile was investigated experimentally using a large-scale laboratory testing system. The vibro-driving model predicted the observed driving history reasonably well.A computer program (UHVIBRO) has been developed to analyse vibratory pile driving using the dynamic soil resistance relationships developed along with correlation factors from the systematic laboratory study.

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Rational Wave Equation Model for Pile‐Driving Analysis

Cited by 77 publications

References 12 publications

Assessment of Axially-Loaded Pile Dynmaic Design Methods and Review of INDOT Axially-Loaded Design Procedure

Assessment of Axially-Loaded Pile Dynmaic Design Methods and Review of INDOT Axially-Loaded Design Procedure

Prediction of pile capacity from stress‐wave measurements: Some numerical aspects

Modelling of vibratory pile driving in sand

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