Becker and standard penetration tests (BPT–SPT) correlations with consideration of casing friction

1994 ◽  
Vol 31 (3) ◽  
pp. 343-356 ◽  
Author(s):  
Alex Sy ◽  
R.G. (Dick) Campanella
Keyword(s):  
British Columbia ◽  
Energy Transfer ◽  
Stress Wave ◽  
Standard Penetration Test ◽  
Energy Output ◽  
Rational Approach ◽  
Stress Wave Propagation ◽  
Penetration Test ◽  
In Situ Tests ◽  
Foundation Design

The Becker penetration test (BPT), through correlations with the standard penetration test (SPT), is widely used for foundation design and liquefaction assessment in gravelly soils. Most of the existing correlations, however, do not adequately account for the variable energy output of the diesel hammer used in the Becker system, and shaft friction on the Becker casing is ignored. An alternative and more rational approach to BPT–SPT correlations is presented, based on experimental and numerical studies conducted at the University of British Columbia. The research involves performing SPT, BPT, and other in situ tests at several sites in British Columbia and includes dynamic measurements of energy transfer in the SPT and BPT. Stress-wave measurements and wave-equation analyses are used to evaluate the effect of friction on the BPT blow count. New BPT–SPT correlations are proposed that consider the energy transfer in both tests and explicitly consider casing friction in the BPT. A recommended procedure for estimating equivalent SPT N60 from BPT blow count is presented. Key words : Becker penetration test, standard penetration test, dynamic measurement, pile driving, stress-wave propagation.

Dynamic performance of the Becker hammer drill and penetration test

1993 ◽  
Vol 30 (4) ◽  
pp. 607-619 ◽  
Author(s):  
Alex Sy ◽  
R.G. (Dick) Campanella
Keyword(s):  
Dynamic Performance ◽  
Drill Pipe ◽  
Standard Penetration Test ◽  
Extensive Study ◽  
Coarse Grained ◽  
Energy Output ◽  
Stress Wave Propagation ◽  
Penetration Test ◽  
Foundation Design ◽  
Variable Energy

The Becker penetration test (BPT) blow counts are commonly correlated to the standard penetration test (SPT) N-values for foundation design and liquefaction potential assessment in coarse-grained soils. Most of the existing correlations, however, do not adequately account for the variable energy output of the ICE 180 diesel hammer used in the Becker system, and the shaft resistance acting on the Becker pipe is often ignored. To obtain reliable BPT–SPT correlations, an extensive study of the BPT has been conducted at several sites in British Columbia. Dynamic measurements of Becker drill rigs and penetration tests were conducted that included hammer combustion and bounce chamber pressures, as well as force and acceleration near the top of the drill pipe. The dynamic field data are presented, including the maximum energy transferred to the top of the Becker pipe (ENTHRU). An energy approach for correcting Becker blow counts to a reference ENTHRU level of 30% of the hammer-rated energy is proposed. Different combustion conditions, drill rigs, and pipe sizes are investigated in the study. The test results show that ENTHRU is a fundamental and useful parameter for normalizing the BPT blow counts to account for the variable energy transfer from the diesel hammer. Key words : penetration test, dynamic measurement, energy, pile driving, diesel hammer, stress-wave propagation.

scholarly journals PROPOSTA DE APLICAÇÃO DE RESULTADOS DE SONDAGENS COM MARTELO LEVE (DPL) NO CAMPO EXPERIMENTAL DA UNIFOR EM PROJETOS DE FUNDAÇÕES PARA PEQUENAS CARGAS [ Proposal for the Application of Dynamic Probing Light (DPL) Results in the Experimental Field of UNIFOR in Foundations Projects for Small Loads ]

2018 ◽  
Vol 14 (2) ◽  
Author(s):  
Marcos Fábio Porto de Aguiar ◽  
Fernando Feitosa Monteiro ◽  
Francisco Heber Lacerda de Oliveira ◽  
Yago Machado Pereira de Matos
Keyword(s):  
Bearing Capacity ◽  
Standard Penetration Test ◽  
Coefficient Of Determination ◽  
Deep Foundations ◽  
Penetration Test ◽  
In Situ Tests ◽  
Foundation Design ◽  
Experimental Field

RESUMO: Em meio aos diversos métodos utilizados no Brasil para determinação da capacidade de carga de fundações, a grande maioria parte do índice de resistência à penetração (NSPT). Para o caso de pequenas edificações, devido a fatores geralmente econômicos, a experiência ou a prática regional costumam prevalecer. Sendo assim, são elaborados, muitas vezes, projetos sem um procedimento de cálculo fundamentado em parâmetros comprovados por ensaios geotécnicos, podendo ocasionar problemas na edificação, como recalques excessivos, ou, até mesmo, comprometer a segurança da estrutura. Dessa forma, técnicas mais simples e de baixo custo, como o DPL (Dynamic Probing Light), podem ser uma opção para situações de pequenas cargas, viabilizando projetos fundamentados em ensaios in situ. Partindo de investigações com o DPL, este trabalho tem o objetivo de dimensionar fundações superficiais e profundas para edificações de pequeno porte através de algumas das principais metodologias disponíveis na literatura e verificar a sua eficiência. Por meio de resultados de campanhas de sondagens SPT (Standard Penetration Test) e DPL no campo experimental da Universidade de Fortaleza (UNIFOR), determinou-se a capacidade de carga de fundações superficiais e profundas fazendo aplicação dos índices NSPT e NSPT equivalente obtido pela correlação com o DPL. Identificou-se que essa correlação apresentou coeficiente de determinação satisfatório entre os parâmetros obtidos nos ensaios SPT e DPL para o terreno em questão, mostrando-se o DPL ser uma alternativa pertinente, em termos técnicos para projetos de fundações de obras de pequeno porte.ABSTRACT: Among the various methods used in Brazil of the determination of the bearing capacity on foundations, most part uses the standard penetration resistance (NSPT). For small constructions, due to economic factors generally, experience or regional practice usually prevails. Thus, projects without a reasoned calculation procedure in parameters supported by geotechnical tests are often designed, and may cause problems in the building, as excessive settlements, or even compromise the safety of the structure. In this way, simple and low cost techniques such as DPL (Dynamic Probing Light) may be an option for small loads situations, enabling projects based on in situ tests. This paper proposes to calculate the dimensions of shallow and deep foundations for small constructions and check its efficiency using DPL tests. Through the results of SPT (Standard Penetration Test) and DPL tests in the experimental field of the University of Fortaleza (UNIFOR), the determination of the bearing capacity in shallow and deep foundations was done using NSPT index and equivalent NSPT index obtained by the correlation with DPL. A correlation with satisfactory coefficient of determination was obtained between SPT and DPL tests parameters for the analyzed field, showing up the DPL as an appropriate alternative in technical terms for foundation design of small constructions.

Assessment of the range of variation of Nγ from 60 estimation methods for footings on sand

2013 ◽  
Vol 50 (7) ◽  
pp. 793-800 ◽  
Author(s):  
Edgar Giovanny Diaz-Segura
Keyword(s):  
Friction Angle ◽  
Standard Penetration Test ◽  
Estimation Methods ◽  
Penetration Test ◽  
In Situ Tests ◽  
Vertical Loading ◽  
Simplified Method ◽  
Bearing Capacity Factor ◽  
Range Of Variation

The range of variation of the bearing capacity factor, Nγ, was assessed using 60 estimation methods for rough footings on sand subjected to static vertical loading. The influence on the Nγ values of the use of correlations for the estimation of the friction angle, [Formula: see text], derived from in situ tests was also assessed. The analysis shows a marked dependency on the methods used to determine Nγ, showing differences for the same [Formula: see text] values of up to 267% between estimated values. Uncertainty in the estimation of [Formula: see text], due to the use of correlations with in situ tests, leads to a range of variation for Nγ higher than that seen using the 60 estimation methods. Finally, given the regular use of the in situ standard penetration test (SPT) on sands, and based on a series of analyses using finite elements, a simplified method in terms of the SPT N-values is proposed for estimation of Nγ in footings on sands.

A Parabolic Theory of Stress Wave Propagation Through Inhomogeneous Linearly Elastic Solids

1977 ◽  
Vol 44 (3) ◽  
pp. 462-468 ◽  
Author(s):  
J. J. McCoy
Keyword(s):  
Wave Propagation ◽  
Energy Transfer ◽  
Numerical Computation ◽  
Stress Wave ◽  
Wave Equations ◽  
Coupled System ◽  
Wave Theory ◽  
Propagation Direction ◽  
Stress Wave Propagation ◽  
Elastic Solids

A theory, in the form of a coupled system of reduced parabolic wave equations (equations (42)), is developed for stress wave propagation studies through inhomogeneous, locally isotropic, linearly elastic solids. A parabolic wave theory differs from a complete wave theory in allowing propagation only in directions of increasing range. Thus, when applicable, it is well suited for numerical computation using a range-incrementing procedure. The parabolic theory considered here requires the propagation directions to be limited to a cone, centered about a principal propagation direction, which might be described as narrow-angled. Further, the theory requires that the effects of diffraction, refraction, and energy transfer between the dilatational and distortional modes are gradual enough that coupling between them can be ignored over a range of several wavelengths. Precise conditions for the applicability of the theory are summarized in a series of inequalities (equations (44)).

Design load of rigid footings on sand

2010 ◽  
Vol 47 (8) ◽  
pp. 872-884 ◽  
Author(s):  
Edgar G. Diaz ◽  
Fernando Rodríguez-Roa
Keyword(s):  
Standard Penetration Test ◽  
Design Criterion ◽  
Cohesionless Soil ◽  
Unit Weight ◽  
Embedment Depth ◽  
Penetration Test ◽  
Soil Pressure ◽  
In Situ Tests ◽  
Vertical Loading ◽  
Design Load

Experimental evidence has shown that most current methods are not able to predict design loads of footings on cohesionless soil with an acceptable degree of accuracy. In the present study, a simple and realistic settlement-based method is proposed to estimate the design load of rigid footings on sand subjected to static vertical loading. The design criterion based on restricting the end-of-construction settlement to 16 mm because of the inherent variability of the real soil deposits is herein adopted. A series of finite-element analyses based on an advanced constitutive model were carried out to study the load–settlement response of footings supported on 14 sandy soils. Routine design charts were developed to predict the net allowable soil pressure of footings on normally consolidated and overconsolidated sands. These charts consider footing shape, embedment depth, grain diameters D10 and D60, particle shape, unit weight (or submerged unit weight for saturated sands), and indirect measurements of the shear strength derived from in situ tests, such as relative density, standard penetration test (SPT) or cone penetration test (CPT). As shown, the proposed charts match well with available experimental data.

scholarly journals Shear wave velocity by support vector machine based on geotechnical soil properties

2014 ◽  
Vol 2 (4) ◽  
pp. 2443-2461 ◽  
Author(s):  
I. Shooshpasha ◽  
A. Kordnaeij ◽  
U. Dikmen ◽  
H. MolaAbasi ◽  
I. Amir
Keyword(s):  
Support Vector Machine ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Effective Means ◽  
Standard Penetration Test ◽  
Support Vector ◽  
Soil Parameters ◽  
Penetration Test ◽  
In Situ Tests

Abstract. Shear wave velocity (VS) is a basic engineering property implemented in evaluating the soil shear modulus. In many instances it may be preferable to determine VS indirectly by common in-situ tests, such as the Standard Penetration Test (SPT). In this paper, the relationship between VS and geotechnical soil parameters such as standard penetration test blow counts (N160), effective stress and fines content, as well as overburden stress ratio (σvo/σ′vo), is investigated. A new mode based on support vector machine (SVM) approach is proposed to correlate geotechnical parameters and VS, predicated on a total of 620 data sets, including field investigation records for the Kocaeli (Turkey, 1999) and Chi-Chi (Taiwan, 1999) earthquakes. This study addresses the question of whether Support Vector Machine (SVM) approach should be used to estimate VS based on the specified geotechnical variables, and assessing the influence of each variable on VS. Results revealed that SVM, in comparison to previous statistical relations, provides an effective means of efficiently recognizing the patterns in data and accurately predicting the VS.

scholarly journals Effect of Hammer Shape on Energy Transfer Measurement in the Standard Penetration Test

2004 ◽  
Vol 44 (3) ◽  
pp. 103-114 ◽  
Author(s):  
Jiin-Song Tsai ◽  
Yean-Jhe Liou ◽  
Fu-Chen Liu ◽  
Chin-Huei Chen
Keyword(s):  
Energy Transfer ◽  
Standard Penetration Test ◽  
Penetration Test ◽  
Transfer Measurement

Standard penetration test energy measurements using a system based on the personal computer

1992 ◽  
Vol 29 (4) ◽  
pp. 551-557 ◽  
Author(s):  
Peter K. Robertson ◽  
David J. Woeller ◽  
Kofi O. Addo
Keyword(s):  
Energy Transfer ◽  
Test Procedure ◽  
Standard Penetration Test ◽  
Energy Calibration ◽  
Calibration System ◽  
Penetration Test ◽  
Reference Test ◽  
Time Record ◽  
Force Time

According to the International Reference Test procedure for the standard penetration test (SPT), in situations where comparisons of SPT results are important, calibrations should be made to evaluate the efficiency of the equipment in terms of energy transfer. However, equipment to measure the energy transfer of the hammer anvil system is not commonly available. Ten years ago a system was developed and made commercially available. However, this system is no longer available. An SPT energy calibration system is described that has been developed based on a microcomputer. The load cell to measure the compressive stress wave beneath the SPT anvil consists of a 0.5-m length of strain-gauged AW rod. Specialized software has been developed to record the force–time record for each hammer blow on a portable microcomputer. Examples of energy measurements are presented and discussed. Key words : standard penetration test, in situ, microcomputer, energy.

Sign in / Sign up

Export Citation Format

Share Document