This paper presents novel measurement data on the dynamic soil–structure interaction of an end-bearing pile foundation. The purpose is to assess the ability to predict the foundation impedances based ...on the small-strain properties of the soil obtained from site investigations. Measurements were performed in two stages of construction, allowing to assess interaction between the piles through the soil. First, single pile impedances and interaction factors between the piles were experimentally obtained for the four piles when they were free to move at the surface. Second, the impedances of the square pile group were measured after casting a concrete pile cap. The piles were additionally instrumented with accelerometers at depth along the centerline of each pile, allowing to illustrate the global behaviour of the piles within the soil. Numerical predictions based solely on information of the small-strain soil properties obtained from extensive site investigations are compared to the experimental results. The impedances of the individual piles are overestimated compared to the measurements, while the interaction factors show a better agreement. The pile group impedances are better captured than the individual ones, using the same soil model. The pile–soil–pile interaction is clearly manifested in the experimental results by pronounced peaks in the pile group vertical impedance, validating results from previous numerical studies.
•Experimental impedances are retrieved for end-bearing piles and a pile group.•Pile–soil–pile interaction experimentally identified before and after casting of a concrete pile cap.•Class A predictions obtained from a linear elastic numerical model show close agreement with measurements.•Measurements are performed at depth within the piles providing novel measurement data on the dynamic soil–structure interaction of an end-bearing pile foundation.
A significant objective in the design and implementation of capable and cost-effective pile foundations is the enhancement of their lateral capacity when lateral load is applied. This study offers a ...nonlinear 3D analysis of pile-soil interaction. The ways that piles behave are examined in this research, with a sequence of laboratory model tests conducted to develop p-y curves of laterally loaded finned and regular piles in multilayered sandy soil from Karbala city in Iraq. To clarify the effects of group interaction, pile type, pile group patterns, and spacing ratios were analyzed, and from the investigational tests, p-multipliers values were identified.
Axial bearing capacity of piles is the most important parameter in pile foundation design. In this paper, artificial neural network (ANN) and random forest (RF) algorithms were utilized to predict ...the ultimate axial bearing capacity of driven piles. An unprecedented database containing 2314 driven pile static load test reports were gathered, including the pile diameter, length of pile segments, natural ground elevation, pile top elevation, guide pile segment stop driving elevation, pile tip elevation, average standard penetration test (SPT) value along the embedded length of pile, and average SPT blow counts at the tip of pile as input variables, whereas the ultimate load on pile top was considered as output variable. The dataset was divided into the training (70%) and testing (30%) parts for the construction and validation phases, respectively. Various error criteria, namely mean absolute error (MAE), root mean squared error (RMSE), and the coefficient of determination (R2) were used to evaluate the performance of RF and ANN algorithms. In addition, the predicted results of pile load tests were compared with five empirical equations derived from the literature and with classical multi-variable regression. The results showed that RF outperformed ANN and other methods. Sensitivity analysis was conducted to reveal that the average SPT value and pile tip elevation were the most important factors in predicting the axial bearing capacity of piles.
A novel pile‐to‐pile interaction model for pipe piles that considers the soil‐plug effect is established based on the Novak plane‐strain soil model. Subsequently, the pipe‐pile dynamic interaction ...factor and dynamic impedance of pipe‐pile groups are derived using the superposition method. The accuracy of the proposed analytical solution is confirmed by comparison with experimental results and existing solutions. Finally, numerical results are obtained to study the influence of the soil‐plug height, shear modulus of the soil, pile spacing, and pile outer radius on the pipe‐pile dynamic interaction factor and dynamic impedance of pipe‐pile groups. The results indicate that the effect of the soil‐plug height on the pipe‐pile dynamic interaction factor and dynamic impedance is significant, whereas the shear modulus of the soil plug has virtually no effect. The proposed analytical solution can be applied to determine the optimal values of pile and soil parameters during the dynamic design of pipe‐pile groups.
To date, the electrokinetic (EK) method has only been used to increase the bearing capacity of steel piles. This study analysed the impact of EK on the bearing capacity of reinforced cement concrete ...piles (RCCP), reinforced lime-cement concrete piles (RLCCP), and steel piles located in kaolin clay. The performance of four different cathodes was also evaluated, and the iron electrode was found to be the most effective cathode for use in the EK process. Unlike RLCCP, the bearing capacity of 7 day cured RCCP with 5 day EK decreased due to corrosion in the pile body. However, the addition of lime to RCCP significantly increased the pile bearing capacity by 57.8% with 8 day EK and prevented damage and corrosion in the pile body. It is concluded that EK can effectively increase the bearing capacity of both metallic and even concrete piles.
While design methods of deep foundations are mainly developed for homogenous soil deposits, the presence of highly cemented layers could lead to underestimation of resistance and overestimation of ...settlement of pile foundations. This study presents a novel approach using competent caliche layers bonded to the top and bottom of a continuous flight auger (CFA) pile as a new composite foundation system named caliche stiffened pile (CSP). The key objective is to optimize the required pile length in a cost-effective approach without ameliorating soil properties. Settlements of the CSP foundation for a high-rise building were monitored and full-scale tests were conducted to measure piles’ capacity. Finite element back analyses were performed to avoid adverse effect of sample disturbance in settlement calculations. A back calculation of a test fill embankment was performed to determine soil stiffness parameters by simulating an unscheduled imposed load to the structure. Impacts of the CSP on controlling the settlement of pile foundation and optimizing the required pile length are investigated using finite element analysis and a parametric study. The proposed CSP foundation can reduce the CFA pile settlement significantly in the presence of caliche layers with thickness equal or greater than a pile diameter at CFA pile head and toe, where the CSP is located.
End bearing response of open-ended pipe piles embedded in rock Jafari, Mustafa; Gharsallaoui, Haythem; Victor, Karl Henry ...
International journal of rock mechanics and mining sciences (Oxford, England : 1997),
July 2019, 2019-07-00, 20190701, Volume:
119
Journal Article
Peer reviewed
Prediction of bearing capacity of steel pipe piles in rock masses is an important consideration in civil engineering especially as such prediction influences the safety of the supported ...superstructures as well as the pile integrity in pile driving operations. Provided that the rock mass is described as a linear elastic and perfectly plastic material obeying the Hoek-Brown failure criterion, a finite element analysis is performed to investigate the embedment depth effect on the annular base bearing capacity and the failure mechanism of typical open-ended pipe piles in sedimentary rock masses. The pipe pile has smooth walls and rough toe surface. Annular toe resistance of pipe piles can serve as an estimate of the rock mass resistance to driving in a fully coring mode which is usually expected for large diameter open-ended pipe piles. Pipe pile results are also extended to circular piles and embedded strip foundations socketed in rock masses. The analysis is shown to highlight the influence of the annular geometry of the pipe pile causing an unsymmetrical failure mechanism with respect to pipe wall center as well as an inclination of rock mass reaction, which if sufficiently large, may lead to pile convergence and damage during pile driving operations. The failure mechanism legitimates the plug tendency to rise up in the pipe and explains the plug formation. The study demonstrates that in most practical applications, the bearing capacity of pipe piles approaches a limiting value, which is less than or at most equal to the end bearing capacity of an embedded strip foundation of width equal to the pipe wall thickness. A comparison has been made with experimental data. It is shown that the results are relatively in good agreement with test data in terms of rock mass resistance and the mechanism of rock plug formation.
The offshore pile foundations are subjected to lateral cyclic loadings such as winds, waves, and currents with complex force characteristics, which can cause complex structure responses. In this ...paper, the discrete element method (DEM) is used to carry out a numerical study on the force characteristics of open-ended pipe piles under lateral loading. The simulation results show that the pile rotates under cyclic loading, the centre of rotation is about 85% of the buried depth of the pile, and the cumulative angle of the pile is less than 0.1°. When a periodic load is applied, the soil around the pile is disturbed, resulting in plastic displacement, and the soil affected area around the pile forms a “butterfly shape”. The displacement in the “active zone” is larger than that in the “passive zone”. As the cycle time increases, the horizontal stiffness gradually decreases in the first 10 cycles, and the attenuation amplitude reaches more than 29% after 100 cycles. The reduction of the internal and external frictional resistance of the pile mainly occurred in the first 10 cycles, and the reduction was less than 15%. It can be seen from the static p-y curve of the pile foundation after cyclic loading that the larger the load amplitude, the greater the reduction in the bearing capacity of the pile foundation under cyclic loading. In addition, the reduction in the bearing capacity of the pile foundation under one-way loading is larger than that under two-way loading.
•The double-wall model pipe pile numerical model was used innovatively.•It can effectively separate the inner and outer friction resistance of the open pipe pile under the horizontal cyclic load.•It studied the influence of unidirectional and bidirectional cyclic load on the bearing performance of pile foundation.•The attenuation mainly occurs in the first 10 cycles, and it accounts for more than 80% of the total attenuation.•The reduction in the bearing capacity of the pile foundation under one-way loading is larger than that under two-way loading.
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