Pullout behaviour of model pile and helical pile anchors Subjected to lateral cyclic loading

1994 ◽  
Vol 31 (1) ◽  
pp. 110-119 ◽  
Author(s):  
Y.V.S.N. Prasad ◽  
S. Narasimha Rao
Keyword(s):  
Cyclic Loading ◽  
Clayey Soil ◽  
Pullout Capacity ◽  
Lateral Deflection ◽  
Degradation Factor ◽  
Model Pile ◽  
Helical Piles ◽  
Load Tests ◽  
Rigid Model ◽  
Pullout Behaviour

This paper presents the effect of lateral cyclic loading on the pullout capacity of model and helical piles in clayey soil. The tests were conducted on short rigid model piles in the laboratory in three phases, namely lateral static load tests, lateral cyclic load tests, and vertical pullout tests. From the test results it was found that the lateral cyclic loading affects the pullout capacity of piles substantially. Reduction in pullout capacity mainly depends upon the lateral deflection of the pile during cyclic loading and the embedment ratio of the pile. This reduction in the pullout capacity of model piles is presented in terms of nondimensional parameters, viz., degradation factor, lateral deflection ratio, and embedment ratio of pile. However, in the case of helical piles under similar conditions, it was found that the lateral cyclic loading has very little influence on the pullout capacity. The reasons for the better performance of helical piles over ordinary piles are explained. Key words : clay, degradation factor, helical pile, lateral cyclic loading, lateral deflection, Joading level, pile, pullout capacity.

Numerical Simulation of Bored Pile-Soil Interface Shear Performance

2013 ◽  
Vol 438-439 ◽  
pp. 1427-1432
Author(s):  
Qian Xu Liao ◽  
Jin Cao ◽  
Jun Wei Tang
Keyword(s):  
Numerical Simulation ◽  
Clayey Soil ◽  
Frictional Resistance ◽  
Measured Data ◽  
Interface Shear ◽  
Bored Pile ◽  
Model Pile ◽  
Shear Performance ◽  
Bored Piles ◽  
Soil Interface

This paper derives a numerical simulation of direct shearing test and model pile test based on the measured data of bored piles. Characteristics of the interface between bored pile and soil around it are analyzed. Laws of the magnitude and the distribution range of point resistance and frictional resistance of the bored piles in granular and clayey soil are obtained and the mechanism on them is explained.

Helical Pile Capacity-to-Torque Correlation: A More Reliable Capacity-to-Torque Factor Based on Full Scale Load Tests

2020 ◽  
Vol 14 (2) ◽  
Author(s):  
Moncef Souissi
Keyword(s):  
Axial Load ◽  
Static Load ◽  
Full Scale ◽  
Load Direction ◽  
Pile Capacity ◽  
Helical Piles ◽  
Load Tests ◽  
High Torque ◽  
Low Torque ◽  
The One

The capacity-to-torque ratio, Kt, has been used in the design of helical piles and anchors for over half a century. Numerous research efforts have been conducted to accurately predict this capaci-ty-to-torque ratio. However, almost of all these Kt factors are based on shaft geometry alone. The ca-pacity-to-torque ratio described herein was found to depend on the shaft diameter, shaft geometry, helix configuration, axial load direction, and installation torque. In this study, 799 full scale static load tests in compression and tension were conducted on helical piles of varying shaft diameters, shaft geometry, and helix configurations in different soil types (sand, clay, and weathered bedrock). The collected data were used to study the effect of these variables on the capacity-to-torque ratio and resulted in developing a more reliable capacity-to-torque ratio, Km, that considers the effect of the variables mentioned above. The study shows that the published Kt values in AC358 (ICC-ES Acceptance Criteria for Helical Piles Systems and Devices) underestimate the pile capacity at low torque and overestimate it at high torque. In addition, and based on probability analysis, the predicted capacity using the modified Km results in a higher degree of accuracy than the one based on the published Kt values in AC358.

scholarly journals Pile lateral subgrade reaction modulus for Jakarta

2019 ◽  
Vol 270 ◽  
pp. 02002
Author(s):  
Saskia Nadilla ◽  
Widjojo Adi Prakoso
Keyword(s):  
Load Cycle ◽  
Reaction Model ◽  
Lateral Loads ◽  
Subgrade Reaction ◽  
Lateral Deflection ◽  
Linear Elastic ◽  
Construction Methods ◽  
Cyclic Lateral Load ◽  
Load Tests ◽  
Laterally Loaded

The behavior of laterally loaded piles could be simulated by the subgrade reaction model. The primary soil parameter for this model is the subgrade reaction modulus, and in this paper, the correlation between the subgrade reaction modulus and the soil N-SPT value is examined by conducting numerical analyses of 34 pile cyclic lateral load tests in Jakarta. In each analysis, the pile is modeled as a series of beam elements, while the surrounding soil is modeled as a series of linear elastic springs. The moduli are varied according to the N-SPT values recorded in the associated deep boring data. In each load cycle, a trial and error process is conducted to match the resulting pile head lateral deflection to the measured value. The resulting correlation between the subgrade reaction modulus and the pile lateral deflection is presented for the 34 case studies and compared to a correlation in the literature. Furthermore, the analyses reveal that subgrade reaction modulus is affected by the magnitude of measured deflection, by the applied lateral loads, as well as by the construction methods.

scholarly journals Large-diameter helical pile capacity – torque correlations

2017 ◽  
Vol 54 (7) ◽  
pp. 968-986 ◽  
Author(s):  
Jared Harnish ◽  
M. Hesham El Naggar
Keyword(s):  
Large Diameter ◽  
Failure Criteria ◽  
Load Test ◽  
Ultimate Capacity ◽  
Pile Capacity ◽  
Shearing Resistance ◽  
Helical Piles ◽  
Torque Capacity ◽  
Load Tests ◽  
Pile Load Tests

Large-diameter helical piles are utilized increasingly to support heavy structures. Both the magnitude of the required installation torque and the pile capacity can be directly attributed to the soil shearing resistance developed over the embedded area of the pile including the shaft and helical plates. Hence, the pile capacity can be correlated to installation torque. Such correlations are widely used in the helical pile industry as a means for quality control and quality assurance. In the current study, a total of 10 test piles were installed while monitoring the installation torque continuously with depth. The recorded installation torque profiles were demonstrated to be accurate and repeatable. Field pile load tests were conducted and their results were analyzed to determine the interpreted ultimate capacity of the test piles. The results demonstrate that the ultimate capacity of large-diameter helical piles can be interpreted from pile load test data employing the failure criteria proposed by Elkasabgy and El Naggar in 2015 and Fuller and Hoy in 1970. The measured installation torque and corresponding ultimate capacity values were employed to define torque–capacity correlation (Kt) based on embedded pile area. It was demonstrated that the proposed Kt is suitable for large-diameter helical piles.

Cyclic axial loads on piles: Analysis of existing data

1986 ◽  
Vol 23 (3) ◽  
pp. 362-371 ◽  
Author(s):  
Jean-Louis Briaud ◽  
Guy Y. Felio
Keyword(s):  
Data Base ◽  
Laboratory Tests ◽  
Ocean Waves ◽  
Cyclic Behavior ◽  
Axial Loads ◽  
Soil Stiffness ◽  
Model Pile ◽  
Load Tests ◽  
Pile Load Tests ◽  
Number Of Cycles

A data base is collected to study the behavior of piles in clay under cyclic axial loads generated by ocean waves. The data base includes 9 studies on the cyclic behavior of clay samples in laboratory tests, 10 studies on cyclic model pile load tests in clay, and 16 studies on cyclic full-scale pile load tests in clay of which 4 studies are proprietary. First, general conclusions are drawn from inspection of these studies. Then a power law model is used to quantify the soil stiffness degradation as the number of cycles increases. The parameter for the model is back-figured for each case of the data base and general trends are observed. Key words: pile load tests, cyclic loads, laboratory tests, clay.

scholarly journals An experimental investigation for pullout response of a single granular pile anchor in clayey soil

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Hans Raj Vashishtha ◽  
Vishwas A. Sawant
Keyword(s):  
Clayey Soil ◽  
Expansive Soil ◽  
Diameter Ratio ◽  
Upward Movement ◽  
Pullout Capacity ◽  
Granular Pile ◽  
Steel Tank ◽  
Pullout Load ◽  
Anchor Plates ◽  
Length To Diameter Ratio

AbstractThe granular pile anchor foundation is an effective and economical foundation system to counter the pullout forces exerted in case of transmission towers or foundations in expansive soil. The pullout tests were performed to study the behaviour of a single granular pile anchor in the clayey soil bed. Tests were conducted in a steel tank of 1 ×  1  ×  1 m size with the help of loading frame arrangement. The pullout load required for upward movement equal to 10% diameter was considered as the pullout capacity of the granular pile anchor. In the parametric study, length and diameter of the granular pile anchor were varied to examine their effect. Number of anchor plates was also varied in few tests. The pullout capacity enhanced with an increase in the diameter and length to diameter ratio. The effect of the length to diameter ratio was appreciable up to the value of 10. However, no significant effect was found in the cases of multiple anchor plates. A relationship is proposed to predict normalized pullout capacity.

Axial response of piles in electrically treated clay

1999 ◽  
Vol 36 (3) ◽  
pp. 418-429 ◽  
Author(s):  
M Abdel-Meguid ◽  
M H El Naggar ◽  
J Q Shang
Keyword(s):  
High Voltage ◽  
Large Scale ◽  
Axial Loading ◽  
Soil Improvement ◽  
Pullout Capacity ◽  
Axial Capacity ◽  
Testing Facility ◽  
Load Tests ◽  
Pile Load Tests ◽  
Marine Clays

Improvement of the shear strength of soft clayey soils around steel pipe piles using high-voltage electrokinetics is investigated in the present study. The experimental setup of a large-scale testing facility is described. Four model piles were installed in two identical cylinders filled with simulated marine sediment. Five electrically insulated electrodes were installed close to the piles to apply a high-voltage electric field in the test cylinder. Negative direct current voltages of -20, -30, and -10 kV were applied in three phases, respectively, for 33 days in the treatment cylinder. Axial compression and pullout pile load tests were performed and the results were compared for both cylinders after each phase of treatment. The pile response is presented in terms of the experimental load deflection curves. It is observed that the axial capacity was increased 30, 29, and 8% after the first, second, and third treatment phases, respectively. The pullout capacity was increased due to the treatment by 11, 23, and 12% after the first, second, and third treatment phases, respectively. Further development of this technique may provide potential solutions for the improvement of soft marine clays, and ultimately it could be applied in the field to rehabilitate existing offshore foundations.Key words: electrokinetics, piles, marine clays, soil improvement, bearing capacity, axial loading.

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