scholarly journals Use of the dynamic load test to obtain the pile capacity – the Brazilian experience

DYNA ◽  
2021 ◽  
Vol 88 (217) ◽  
pp. 169-177
Author(s):  
Tiago de Jesus Souza ◽  
André Querelli ◽  
Felipe Vianna Amaral de Souza Cruz ◽  
Pablo Cesar Trejo Noreña
Keyword(s):  
Dynamic Load ◽  
Load Capacity ◽  
Test Procedure ◽  
Field Tests ◽  
Load Test ◽  
Deep Foundations ◽  
Pile Capacity ◽  
Dynamic Load Test ◽  
Load Tests ◽  
Semi Empirical

The dynamic load test is currently an important and usual tool for design, control, and quality assurance of deep foundations. The objective of this paper is to compare the expected geotechnical load capacity through empirical and semi-empirical Brazilian methods with the ultimate pile load obtained from the interpretation of Dynamic Load Tests (DLT; PDA). The stress-settlement curve was constructed from CAPWAP analysis with blows of different drop heights of increasing energy – test procedure proposed by Aoki (1989). Continuous flight augering (CFA) Franki and Root piles were evaluated in this study. These piles were tested in different cities in Brazil. Additionally, DLT results were compared with static load tests, and a good correlation was found with these field tests. The article aims to provide comparative background to guide foundation designers, as well as those who routinely develop these projects in Brazil.

scholarly journals RECALQUES EM FUNDAÇÕES PROFUNDAS – ANÁLISE EM ESTACAS HÉLICE CONTÍNUA

2017 ◽  
Vol 14 (1) ◽  
Author(s):  
Pedro Lucas Prununciati ◽  
Jean Rodrigo Garcia ◽  
Tiago Garcia Rodriguez
Keyword(s):  
Sampling Error ◽  
Load Capacity ◽  
Limit State ◽  
Load Test ◽  
Limiting Factor ◽  
Deep Foundations ◽  
Slow Type ◽  
Load Tests ◽  
Penetration Tests ◽  
The City

RESUMO:  O recalque em fundações profundas e sua influência numa edificação tem se mostrado um parâmetro crítico, já que em diversos projetos a capacidade de carga não é o fator limitante, mas sim o recalque que a estrutura pode suportar em seu estado limite de serviço (ELS). Neste trabalho, são analisados resultados de deslocamento para uma estaca, estimados a partir dos métodos de Poulos e Davis (1980), Vésic (1969, 1975a) e Cintra e Aoki (2010), comparando-os com o valor recalque obtido por ensaios de prova de carga. Para tal, se apresentam três ensaios com carregamento do tipo lento, seguindo instruções da NBR12131 (ABNT, 2006), executados em estacas hélice contínua instrumentadas, com comprimentos de 14,75 m, 12,85 m e 21,80 m e diâmetros de 70 cm, 60 cm e 70 cm, respectivamente. Essas estacas foram ensaiadas no munícipio de Itatiba, em uma região onde sondagens à percussão demonstram a predominância de areia e silte. Para as estacas analisadas, o método proposto por Cintra e Aoki (2010) mostrou melhor resultado para a estimativa do recalque, quando comparado aos resultados de recalque obtidos em prova de carga. O método Poulos e Davis (1980) obteve desempenho menos satisfatório, resultando uma margem de erro de 16%, para mais ou para menos. O método de Vésic (1969, 1975a) se mostrou conservador e, nos casos analisados, resultou uma superestimativa de 138%, quando comparados aos valores de prova de carga.ABSTRACT: The settlement in deep foundations and its influence appears to be a critical parameter, as in many projects, the load capacity of a pile is not the limiting factor, but the settlement which the structure can suffer on its serviceability limit state (SLS) is. In this research, the settlement results of a pile, estimated by the methods of Poulos e Davis (1980), Vésic (1969, 1975a) and Cintra e Aoki (2010) will be analyzed, to be compared with the value of settlement obtained from load tests. Three slow type load tests, following the instructions of NBR12131 (ABNT, 2006) are presented, carried out in instrumented continuous flight augers, with lengths of 14,75 m, 12,85 m and 21,80 m and diameters of 70 cm, 60 cm and 70 cm, respectively. Those piles were tested in the city of Itatiba, in a region where standard penetration tests evidenced the predominance of sand and silt. In the analyzed piles, the Cintra e Aoki (2010) method has shown the best result for a settlement estimate, when compared with the value obtained by a load test. The Poulos e Davis method (1980) obtained a less satisfactory performance, resulting a margin of sampling error of plus or minus 16%. The Vésic method (1969, 1975a) has shown to be conservative, resulting, in the analyzed cases, an overestimate of 138%, when compared with the load tests values.

Driven cast-in-situ pile capacity: insights from dynamic and static load testing

2021 ◽  
Author(s):  
Kevin N. Flynn ◽  
Bryan A. McCabe
Keyword(s):  
Dynamic Load ◽  
Shear Stresses ◽  
Load Testing ◽  
Pile Capacity ◽  
Compression Load ◽  
Shaft Resistance ◽  
Pile Installation ◽  
Cast Concrete ◽  
Load Tests

Driven cast-in-situ (DCIS) piles are classified as large displacement piles. However, the use of an oversized driving shoe introduces additional complexities influencing shaft resistance mobilisation, over and above those applicable to preformed displacement piles. Therefore, several design codes restrict the magnitude of shaft resistance in DCIS pile design. In this paper, a series of dynamic load tests was performed on the temporary steel driving tubes during DCIS pile installation at three UK sites. The instrumented piles were subsequently subjected to maintained compression load tests to failure. The mobilised shear stresses inferred from the dynamic tests during driving were two to five times smaller than those on the as-constructed piles during maintained load testing. This was attributed to soil loosening along the tube shaft arising from the oversized base shoe. Nevertheless, the radial stress reductions appear to be reversible by the freshly-cast concrete fluid pressures which provide lower-bound estimates of radial total stress inferred from the measured shear stresses during static loading. This recovery in shaft resistance is not recognised in some European design practices, resulting in conservative design lengths. Whilst the shaft resistance of DCIS piles was underpredicted by the dynamic load tests, reasonable estimates of base resistance were obtained.

scholarly journals VERIFICAÇÃO DO DESEMPENHO DAS ESTACAS INJETADAS AUTOPERFURANTES EXECUTADAS EM SOLOS ARENOSOS PARA CONSTRUÇÃO DE USINA EÓLICA

2017 ◽  
Vol 13 (2) ◽  
Author(s):  
Rodrigo Cerqueira Rogerio
Keyword(s):  
Structural Characteristics ◽  
Load Capacity ◽  
The Self ◽  
Executive Processes ◽  
Empirical Methods ◽  
Deep Drilling ◽  
Load Tests ◽  
Different Diameters ◽  
Semi Empirical

RESUMO: Apresenta-se neste trabalho a solução adotada para execução das fundações do Parque de Usina Eólica localizado no Ceará, com a utilização das estacas injetadas autoperfurantes, executadas em presença de solos arenosos. No qual consiste em perfurar o solo com altíssima velocidade por rotação e “pull down”, através da injeção simultânea de nata de cimento com medias pressões. Ocasionando na estaca um diâmetro final que pode obter o dobro do bit de perfuração, de acordo com o tipo de solo, gerado pelo efeito do jato da nata de cimento. Detalhando os processos executivos, verificando os aspectos técnicos e operacionais, para melhor compreender as características estruturais deste elemento. De forma a verificar “in situ” o desempenho deste novo tipo de fundação profunda, foram realizadas provas de carga, em estacas com diferentes diâmetros e comprimentos, realizadas em perfis estratigráficos de solos arenosos, para melhor avaliação de sua capacidade de carga. Analisando-se os ensaios das provas de carga interpretados a base da extrapolação da curva carga versus recalque e das previsões da capacidade de carga, obtidas por meio dos métodos semi-empíricos de correlação com ensaios de penetração (SPT), avaliando os padrões de execução desta tipologia de estaca injetada para comunidade geotécnica. ABSTRACT: This paper aims to establish the selected solution to except the foundations of the Wind Energy Park in Ceará (Brazil), with an executive methodology of the self-drilling injection piles framed in loco in Sandy soil. In which the soil drilling is done with the highest speed by rotation and pull down, through the simultaneous injection of grouting with medium pressures. This kind of drilling causes in the pile a final diameter that can get the double bore bit, according to the type of soil, done by the grouting blast. The executive processes are detailed as a whole, and also presenting the pile materials composition, in order to understand the structural characteristics of this element. To verify the performance of this new kind of deep drilling, instrumentations were done: settlement control and load tests in constructions with different structural characteristics, in self-drilling injected piles with different diameters and length, done in stratigraphical sandy, for a better evaluation of its load capacity. Analyzing the essays of load tests interpreted in the basis of curve extrapolation load versus settlement and the previsions of the load capacity, obtained by semi-empirical methods correlating with the penetrations methods (SPT), offering information to the geotechnical community.

scholarly journals Limitations of the Danish driving formula for short piles

2021 ◽  
Vol 44 (2) ◽  
pp. 1-6
Author(s):  
Silvio Heleno de Abreu Vieira ◽  
Francisco R. Lopes
Keyword(s):  
Load Capacity ◽  
Precast Concrete ◽  
Free Fall ◽  
Technical Note ◽  
Driven Piles ◽  
Concrete Piles ◽  
Load Tests ◽  
Semi Empirical ◽  
The City ◽  
Pile Length

Dynamic formulae are a widely used expedient for the control of driven piles to ensure load capacity. These formulae have considerable limitations when used in the prediction of the load capacity on their own, but are very useful in the control of a piling when combined with other tests. This technical note presents an evaluation of the Danish Formula for 54 precast concrete piles, comparing its results with High Strain Dynamic Tests (HSDTs), Static Load Tests (SLTs) and predictions by a semi-empirical static method (Aoki & Velloso, 1975). The data used in the comparison come from three works in the city of Rio de Janeiro, Brazil. All piles were driven with free-fall hammers and in one particular work the piles were relatively short. The predictions of the Danish Formula were evaluated in relation to the pile length/diameter ratio. It was concluded that for short piles - with lengths less than 30 times the diameter - this formula indicates bearing capacities higher than the actual ones. A correction for a safe use of the Danish Formula for short piles is suggested.

scholarly journals Evaluation of bearing capacity of reinforced concrete box ribbed arch bridge based on dynamic load test

2021 ◽  
Vol 233 ◽  
pp. 01047
Author(s):  
Mao He ◽  
Xin Fu ◽  
Shunchao Chen
Keyword(s):  
Reinforced Concrete ◽  
Dynamic Load ◽  
Damping Ratio ◽  
Vibration Characteristics ◽  
Load Test ◽  
Driving Safety ◽  
Original Material ◽  
Arch Bridge ◽  
Dynamic Load Test ◽  
And Function

Dynamic load test is to measure the natural vibration characteristics of the bridge structure or the forced vibration characteristics under dynamic load, and to evaluate the driving performance, driving safety and comfort of the bridge through dynamic load test. In order to evaluate the stress state and working performance of a reinforced concrete box-ribbed arch bridge, the load test of the bridge is carried out. Dynamic load test is used to test the inherent fundamental frequency, damping ratio and impact coefficient of the bridge through pulsation test and sports car test. Through the experiment with the key parts of the stress (strain) and displacement load and other important data, through analysis and study, the comprehensive analysis of the phenomenon of calculation and test, a comprehensive performance evaluation structure and function whether meet the design requirements, to provide technical basis for the safety of the bridge operation, and provide the original material for the bridge maintenance and management in the future.

Predicting the Ultimate Bearing Capacity of Single Piles Based on CPTU

2011 ◽  
Vol 243-249 ◽  
pp. 4402-4407
Author(s):  
Yong Hong Miao ◽  
Guo Jun Cai ◽  
Song Yu Liu
Keyword(s):  
Load Test ◽  
Load Testing ◽  
Pile Capacity ◽  
Piezocone Penetration Test ◽  
Load Carrying ◽  
Load Tests ◽  
Pile Load Test ◽  
Single Piles ◽  
Pile Load Tests ◽  
Best Fit

Six methods to determine axial pile capacity directly based on piezocone penetration test (CPTU) data are presented and evaluated. Analyses and evaluation were conducted on three types piles that were failed during pile load testing. The CPT methods, as well as the CPTU methods, were used to estimate the load carrying capacities of the investigated piles (Qp ). Pile load test were used to determine the measured load carrying capacities (Qm). The pile capacities determined using the different methods were compared with the measured pile capacities obtained from the pile load tests. Two criteria were selected as bases of evaluation: the best fit line for Qp versus Qm and the arithmetic mean and standard deviation for the ratio Qp /Qm. Results of the analyses showed that the best methods for determining pile capacity are the CPTU methods.

Sign in / Sign up

Export Citation Format

Share Document