Prediction of the Axial Bearing Capacity of Piles by SPT-based and Numerical Design Methods (original) (raw)
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2021
Standard Penetration Test (SPT), cohesive soil, spatial variability, variance reduction factor, the scale of fluctuation, bearing capacity of pile Nowadays, in situ tests have played a viable role in geotechnical engineering and construction technology. Besides lab tests conducted on undisturbed soil samples, many different kinds of in-situ tests were used and proved to be more efficient in foundation design such as pressuremeter PMT, cone penetration test CPT, standard SPT, etc. Among them, a standard penetration test (SPT for short) is easy to carry out at the site. For decades, it has proved reliable to sandy soil, but many viewpoints and opinions argued that the test was not appropriately applicable to cohesive soil because of scattered and dispersed data of SPT blow counts through different layers. This paper firstly studies how reliable the SPT data can predict the physical and mechanical properties; secondly, the soil strength is determined in terms of corrected N-SPT values,...
Maǧallaẗ al-abḥāṯ al-handasiyyaẗ, 2022
The objective of this article is to present original research work results on the contribution of the standard penetration test (SPT) to the design and analysis of pile foundations on the basis of the interpretation of a database of full-scale pile loading tests undertaken in sandy soils, with the aim to provide practical recommendations to the designers. The article encompasses three parts, the first one presents a detailed comparative study of 10 currently used methods of design on the basis of the SPT, assessed according to their predictive capability of the axial bearing capacity, within a database consisting of 46 axial pile loading tests carried out in 27 sites in the United Arab Emirates. The second part presents some experimental findings related to the critical (or creep) vertical load, whereas the third part highlights the concept of the reference pile settlement and its application to the limit state design of pile foundations.
Estimation of vertical bearing capacity of piles using the results CPT and SPT tests
Piles as a structural element commonly are employed to overcome the problems like low bearing capacity of subsoil layers, high values of overturning moments, considerable subsidence and etc. However since the very early stage of geotechnical engineering profession, estimation of the bearing capacity of piles had been a challenge for engineers. Using the results of penetrometer tests like Standard Penetration Test (SPT) and Cone Penetration Test (CPT) to estimate the bearing capacity of piles had been the subject of considerable number of researches and several approaches have been proposed. This paper embraces the results of a statistical analysis to compare the results of several direct CPT and SPT methods which commonly are used to estimate the vertical bearing capacity of piles. For this purpose a data bank of full scale pile load tests was compiled. Each case includes the result of CPT and SPT test in the closest possible location to the executed pile. A discussion on the spiral failure zone around the pile's toe which is formed during loading also has been presented.
Contribution to Estimating Bearing Capacity of Pile in Clayey Soils
Civil and Environmental Engineering, 2016
The estimation of real geotechnical parameters is key factor for safe and economic design of geotechnical structures. One of these are pile foundations, which require proper design and evaluation due to accessing more deep foundation soil and because remediation work of not bearable piles or broken piles is a crucial operation. For this reason, geotechnical field testing like cone penetration test (CPT), standard penetration (SPT) or dynamic penetration test (DP) are realized in order to receive continuous information about soil strata. Comparing with rotary core drilling type of survey with sampling, these methods are more progressive. From engineering geologist point of view, it is more important to know geological characterization of locality but geotechnical engineers have more interest above the real geotechnical parameters of foundation soils. The role of engineering geologist cannot be underestimated because important geological processes in origin or during history can expla...
A New Approach to Estimate the Base Bearing Capacity of Driven Piles Based on SPT Data
In recent years, determining bearing capacity of piles from in-situ testing data as a complement of static and dynamic analysis has been used by geotechnical engineers. In this paper, different approaches for estimating base bearing capacity of piles from SPT data has been compared and evaluated. A new method for pile base bearing capacity in sand is proposed using SPT records. Data averaging, failure zone extension, and plunging failure of piles have been addressed in the proposed approach. A data bank comprising 10 full scale static load tests on instrumented piles and 26 dynamic tests, analyzed with signal matching technique by CAPWAP software, was used for validation. The SPT data that was performed close to pile locations is also included in the data base. Comparison of current methods by error investigation with Log-Normal approach demonstrates that the proposed method predicts pile base capacity with more accuracy and less scatter in comparison to other methods.
2016
Cone Penetration Test (CPT or CPTu) is commonly used for estimating soil types and also for the geotechnical design of pile foundation. However, the level of agreement between the CPT-based soil types and the traditional identification of soil types based on samples may vary significantly; and it is not clearly understood if this variation has any sort of relationship with the CPT-based pile design. To investigate into this area, a ground investigation trial was carried out at six different locations as part of a highway scheme in East of England. At each location the trial comprised one CPTu adjacent to one borehole (BH) with conventional sampling and laboratory testing. The soil types were estimated from the CPTs and compared with the boreholes findings, and the levels of correlation between them were established. Similarly, the ultimate bearing capacity of a typical bored pile based on the CPTs and on the BHs were calculated and compared. Despite the variable level of disagreemen...
Pile Load Testing and Determining Bearing Capacity of Cast in Situ Pile: A Case Study
Global Journal of Research In Engineering, 2016
Piles are designed to transfer the load of superstructure to the deeper harder soil strata crossing the upper weaker strata of soil. Cast in situ piles are usually designed by many analyses and using many empirical formulas. But due to a great degree of prevailing uncertainties of subsoil behavior, variation of strata in the same site, diversity in the procedure of construction applied at site, piles are needed to be tested to double or so of design load to verify the conformity with that design load obtained by static design calculation. A case study of load test on a pile of 600mm diameter & length of 35.250m was conducted through ASTM D 1143-81 method. The test load data were collected and converted into graphical forms. The results were interpreted through load-settlement curves applying various methods for determining the allowable load bearing capacity of the pile.
Prediction of pile behavior under static and bi-directional tests and comparison with field results
2017
This paper includes a comparison between the measured data at the occasion of a campaign of full scale static pile load tests performed for the 3 rd Bolivian International Conference on Deep Foundations and the values calculated by means of the software PIVER developed at IFSTTAR and using two kinds of t-z curves: The first one has been developed by Frank and Zhao (1982), and the second one is called AB1 (Abchir and al. 2016). These two kinds of t-z curves are defined by correlations from Ménard pressuremeter tests (PMT) data. The comparison between the measured and the calculated values enables to better estimate the bias and the uncertainty of the two t-z curves used and the method of the calculation of the bearing capacity. 1. INTRODUCTION Pile design is generally based on the calculation of bearing capacity and application of safety factors. These factors aim to limit the load applied on the pile and ensure small displacements for the supported structures. Nevertheless, in some ...
Cone Penetration Test Based Direct Methods for Evaluating Static Axial Capacity of Single Piles
Geotechnical and Geological Engineering, 2013
The direct cone penetration test (CPT) based pile design methods use the measured penetrometer readings by scaling relationships or algorithms in a single-step process to enable the assessment of pile capacity components of shaft and base resistance (f p and q b , respectively) for evaluation of full-size pilings. This paper presents a state-ofthe-art review of published works that focus on direct CPT evaluation of static axial pile capacity. The review is presented in a chronological order to explicate the evolution over the past six decades of an in-situ test based solution for this soil-structure interaction problem. The objective of this study is an attempt to assemble maximum published methods proposed as a result of past investigations in one resource to afford researchers and practitioners with convenient access to the respective design equations and charts. In addition to an all-inclusive summary table and the design charts, a compilation of significant findings and discussions thereof are presented. Furthermore, potential future research directions are indicated, with special emphasis on the optimal use of the modern multichannel hybrid geophysical-geotechnical seismic CPT to evaluate the complete axial pile load-displacement response. Abu-Farsakh MY, Titi HH (2004) Assessment of direct cone penetration test methods for predicting the ultimate capacity of friction driven piles. ASCE J Geotech Geoenviron Eng 130(9):935-944 Almeida MSS, Danziger FAB, Lunne T (1996) Use of the piezocone test to predict the axial capacity of driven and jacked piles in clay. Can Geotech J 33(1):33-41 Alsamman OM (1995) The use of CPT for calculating axial capacity of drilled shafts. PhD Thesis, UIUC, IL, 299 p Altaee A, Fellenius BH, Evgin E (1992) Axial load transfer for piles in sand I: Tests on an instrumented precast pile.