Ultimate Bearing Capacity Of Pile Research Articles

Using Machine Learning to Predict Axial Pile Capacity

Accurate estimation of the ultimate axial load bearing capacity of piles is necessary to ensure the safety of the supported structures and to prevent cost overruns. Traditional mechanics-based design methods do not always predict pile capacity accurately, or precisely, leaving room for improvement. This study focuses on the potential of machine learning (ML) in estimating pile capacity. A dataset of 546 load tests was compiled from three databases. The baseline performance of traditional design methods was first established by comparing the capacities computed using four traditional approaches, against the capacities interpreted from load tests using Davisson’s criterion. Sixteen different ML techniques were explored. First, the optimal feature selection technique for model training was investigated. Second, hyperparameters of each technique were optimized. The process involved the training of 32,000 different models and tuning their hyperparameters. Next the dataset was randomly split into training (70%) and testing (30%) for comparing the 16 different ML regression models. Each of the optimized models was then trained using six feature sets. The performance of each of the 16 ML models with the best performing feature subset was compared with the baseline performance from traditional methods. Evaluation criteria included measured versus predicted capacities, influence of soil type on accuracy, as well as the absence of pile diameter, or length effects on accuracy and precision. In general, the ML methods performed significantly better than the best traditional method. The current research demonstrated that ML may offer advantages in geotechnical design when large datasets are available.

Assessment of ultimate bearing capacity of rock-socketed piles using hybrid approaches

Assessment of ultimate bearing capacity of rock-socketed piles using hybrid approaches

Comparative geotechnical analysis for ultimate bearing capacity of precast concrete piles using cone resistance measurements

Abstract Computing the axial load capacity of pile foundations is often challenging for geotechnical engineers. Different theoretical and empirical approaches were proposed for determining the ultimate bearing capacity. Among these approaches, the in situ testing methods are based on cone penetration test (CPT) measurements. This study compares five CPT methods in estimating the axial load capacity of precast concrete piles evaluated at four piling construction projects in Northwest and Central Florida. The analytical methods used in this work are the Aoki and De Alencar method (1975), the Schmertmann method (1978), the Bustamante and Gianeselli Laboratoire Central des Ponts et Chausees method (1982), the Eslami and Fellenius method (1997), and the Eurocode 7 (2007). The outcomes indicated that the Eurocode method 7 had the most increased load capacity estimates, whereas the Eslami and Fellenius method yielded the lowest estimates. The results also indicated that the Aoki and De Alencar (1975) method consistently demonstrated the slightest differences among these values, showing its potential for reliable and consistent pile-bearing capacity estimations.

Numerical Study on the Effects of Helix Diameter and Spacing on the Helical Pile Axial Bearing Capacity in Cohesionless Soils

The methods employed to calculate the axial bearing capacity of a helical pile depends on the shear failure model around the pile, which is also influenced by the spacing and diameter of the helical plates. However, studies on the transition of the failure mode and the load transfer mechanism with the change of helical plate spacing and diameter in cohesionless soil subjected to axial compressive load have been limited. Thus, this paper investigated the effects of helix diameter and spacing on the axial compressive load-bearing capacity, shear failure model, and load transfer mechanism of helical piles with two helical plates embedded in the homogeneous medium and dense sands, as well as in the stratified medium to very dense sand. Axial loading tests on helical piles with various helix diameters and spacings were simulated using a two-dimensional finite element program with axisymmetric modeling to obtain the load-settlement curve, which was later used to estimate the ultimate bearing capacity of the helical piles. The ultimate bearing capacity of the helical piles was also computed using the conventional methods, i.e., the individual bearing and cylindrical shear methods, and then compared to the numerical-based axial bearing capacity. The stress-strain behaviors of pile and soil were modeled using the Linear Elastic and Mohr-Coulomb material models, respectively. The results show that the numerical-based ultimate bearing capacity of a helical pile increased with increasing the diameter and spacing of the helix. However, the ultimate bearing capacity computed using conventional methods did not show this trend. Then, the transition from the cylindrical shear to the individual bearing failure mechanism occurred at a spacing ratio (i.e., helical plate spacing divided by its diameter) of about two. Ultimately, the load transfer curves indicate that the helical plates mainly supported the applied load.

Assessment of Ultimate Bearing Capacity of Static Loading Pile Based on Cusp Catastrophe Theory

Determining the ultimate bearing capacity of pile is important for reasonable design of the pile. In this paper, a cusp catastrophe theory-based method was proposed for assessing the ultimate bearing capacity of static loading pile. Firstly, a three-parameter quartic polynomial in accordance with the standard form of cusp catastrophe model is proposed and used to fit the experimentally obtained Q–S curve. The parameters which allow the polynomial to produce best fitting to the Q–S curve are taken to identify the stability of the pile following a simple procedure. Then, the proposed method was verified against 10 Q–S curves obtained from field tests at Jinqiao-Meiya and Jinqiao-Chunyu areas of Shanghai. Results show that the ultimate bearing capacities of the piles identified by the proposed method were comparable to those identified by the JGJ 106-2014 standard method. Finally, it is found that the stability of the pile identified by the proposed method and the mechanical state of the pile identified by the Golden Section approach were correlated closely.

Investigation on the bearing capacity evolution of building pile foundation during permafrost degradation

The warming and melting of permafrost due to climate warming pose a considerable threat to the integrity of the Pan Arctic building, thus jeopardizing sustainable development. The increase in ambient temperature in permafrost areas will cause deterioration in the bearing capacity of building pile foundations. Considering the continuous deepening of the active layer (za), the present paper used small-scale physical modeling to investigate the potential variation of bearing capacity and load transfer mechanism of pile foundations under the scenario of continuous degradation of permafrost. The ultimate bearing capacity of a single pile and the undrained shear strength of the ground under different za are estimated by cone penetration tests. In the static load test of single piles, the axial load-settlement, axial force of pile shaft, and earth pressure at the pile tip are measured. The results show that the rise in ground temperature and the deepening of the za shorten the elastic and elastic-plastic stages of the load-displacement curve, resulting in a gradual decline in the bearing capacity of a single pile. The pile-soil interface temperature is always higher than the adjacent ground temperature at the same depth. Adfreezing force of the pile-soil interface decreases due to the increase in ground temperature and water content. With the deepening of za, the peak point of the shaft resistance decreases from −30 cm to −60 cm under the ultimate state. Meanwhile, with more axial load transfer along the pile shaft to the pile tip, the share ratio of pile tip resistance to ultimate stress gradually increases. In addition, the temperature rise of frozen soil at the pile tip accelerates the settling rate of the pile, which eventually causes the pile foundation failure.

Prediction of ultimate bearing capacity of rock-socketed piles based on GWO-SVR algorithm

The application of rock-socketed pile in engineering is becoming ever more common. Finding the ultimate bearing capacity of rock-socketed piles with a high-performance ratio and precision is an important area of research. The rock-socketed piles underwent a field load test, and ABAQUS software was utilized to create a model of the interaction between the pile and the soil. For the geometric and physical parameters of the pile, soil, and bedrock, a total of eighteen pile-soil parameters were chosen. Reasonably constructed orthogonal and control variable tests are utilized, and a sensitivity analysis of the relevant factors is performed. Ten elements that significantly affect the ultimate bearing capacity of rock-socketed piles (with a probability less than 0.05) are selected as the input for the bearing capacity prediction of rock-socketed piles based on the test's consistent findings. The ultimate bearing capacity of rock-socketed piles is predicted using the support vector regression (SVR) model, and the absolute coefficient, mean absolute error (MAE), mean square error (MSE) and other indicators are chosen as the evaluation indices of the model prediction effect. The SVR model predicts an absolute coefficient of 0.7, which is an unsatisfactory prediction outcome. Consequently, the model is optimized via the nested grey wolf (GWO) algorithm. With a value of 0.995, the GWO-SVR model is more akin to 1 than the SVR model. There are 0.14 and 0.034 for the MAE and MSE, respectively. The models of (Artificial bee colony) ABC-SVR, (Cuckoo search) CS-SVR, (Sparrow search algorithm)SSA-SVR, and (Particle swarm optimization) PSO-SVR are built. When comparing different assessment indicators, the GWO-SVR model is smaller than the MAE and MSE. When the prediction model is used on a real project, the engineering requirements can be satisfied by the prediction effect.

Study on bearing characteristics of super-long and super-large diameter pipe piles in silt foundation of alluvial plain of Yellow River

In recent years, super-long and super-large diameter pipe piles have been gradually applied to the foundation in the Yellow River flood area. However, its bearing mechanism is not clear, especially the unclear bearing characteristics of the pile under the eccentric state, which limits its application and development. In this regard, this paper uses the method of combining field test and numerical simulation to analyze the bearing characteristics of super-long and super-large diameter pipe piles under different pile lengths, different pile diameters, different diameter-thickness ratios, and different offsets. Combined with the specific deviation form of the pipe pile, the calculation formula of the vertical ultimate bearing capacity of the super-long and super-long diameter pipe pile in the Yellow River flooding area under the influence of the construction effect is modified. The results show that when the length of the pipe pile changes, the vertical bearing capacity changes the most, and the vertical ultimate bearing capacity of the pipe pile increases linearly with the increase of the length of the pipe pile. When the wall thickness of the pipe pile increases, the vertical bearing capacity increases approximately linearly, but the reduction of the pile displacement decreases exponentially. The greater the deflection of the pipe pile, the smaller the vertical ultimate bearing capacity. When the deflection of the pipe pile is greater than 0.35°, the vertical ultimate bearing capacity decreases rapidly with the increase of the deflection. On the basis of the traditional formula, considering the deviation form of the pipe pile, the reduction coefficient of the bearing capacity correction formula of the super-long and super-large diameter pipe pile is proposed, and the correction formula is compared with the field example. It is proved that the formula can accurately calculate the bearing capacity of the super-long and super-large diameter pipe pile. The research results of this paper are of great significance to the application and promotion of super-long and super-large diameter pipe piles in the Yellow River flood area and the evaluation of vertical ultimate bearing capacity. At the same time, the research results of this paper can also provide a reference for the study of bearing characteristics of super-long and super-large diameter pipe piles in other foundations.

Experimental Evaluations of Model Piles Subject to Inclined Loading in Sand

The structures that subjected to varying loads are supported by pile foundations. These loads consist of inclined and vertical loads. The main objective of this work is to experimentally investigate the effects of an inclined load on the lateral pile reaction and axial pile displacement for piles found in cohesionless soil. For this purpose, the slenderness ratios of model steel piles are varied by values of 11, 14, and 17. Moreover, the pile shapes involved in this study are H-pile, closed end circular and square. The experimental tests were conducted in sandy soil. However, the load inclination angle included in assessing the pile behavior were 0, 30, 45, and 60 from the vertical. In order to study the above parameters on the behavior of model pile, thirty-six experimental tests were carried out. Several findings indicated that the lateral pile deflection was highly influenced by increasing the load inclination. Further, the load inclination effect on the pile's ultimate bearing capacity is high which leads to a reduction in the pile's capacity. Additionally, the vertical displacement of pile is less than horizontal displacement when the pile is subjected to an inclined load of 45° and the model fails by horizontal displacement.

Investigating the influence of root layer quantity on the pullout bearing characteristics of root piles in coral sand foundations

Root piles with good load-bearing characteristics can be used as foundations for offshore wind power facilities. By conducting model tests on root piles with varying numbers of root layers in coral sand foundations and studying the theoretical pullout ultimate bearing capacity, the influence of the number of root layers on the pullout bearing characteristics of root piles is analyzed. Subsequently, a formula for calculating the pullout ultimate bearing capacity of root piles is derived, drawing on the Vesic foundation bearing capacity theory and the Rankine soil pressure theory. The results indicate that increasing the number of root layers enhances the ultimate bearing capacity of root piles, enabling them to better withstand pullout forces and control displacement. The axial force curve of the roots exhibits a step-like pattern. Additionally, the maximum lateral mechanical resistance of the root piles in 3 and 5 layers gradually shifts downwards with increased loading. While the total bearing capacity of the root section increases, the rate of increase diminishes over time. Model test data validates the proposed theoretical formula for calculating bearing capacity, affirming its reliability. These research findings furnish a theoretical groundwork for the practical application of root piles in engineering.

Calculation and Application of Ultimate Lateral Friction Resistance of Concrete Piles under Different Soil Layer Materials

In practical engineering applications, it usually gets the expected value of the ultimate side friction of concrete piles by the empirical parameter method. The expected value of the ultimate side friction of concrete piles cannot achieve maximum optimization due to the complexity of formation conditions and the lack of experience of technicians. To accurately obtain the ultimate lateral friction resistance of piles in homogeneous soil layers, optimize the standard value of pile ultimate lateral resistance, ensure construction safety, and save construction costs, the research method combining theoretical derivation and on-site measurement data validation was done in the manuscript. Based on the shear strength of the pile-soil interface of different materials and the shear performance of the soil around the pile, a calculation equation for the standard value of the ultimate lateral friction resistance of concrete piles in different homogeneous soil materials was derived and applied to the equation for calculating the ultimate bearing capacity of foundation pile and the axial force of pile. Finally, based on an engineering example, the calculated results were compared with the measured resultsThe research results show that in thick coarse-grained soil, as the foundation pile is short, the ultimate bearing capacity of a single pile obtained using the calculation equation deduced in this paper is less than that obtained using the empirical equation provided by the national code. In a deep cohesionless homogeneous soil material, the concrete pile shaft axial force calculation using the pile shaft axial force calculation equation deduced in this paper is close to the measured value when the foundation pile bears the ultimate load; the proposed new method has good application value.

Analysis of the effect of multiple thermal-cold cycles on the bearing performance of phase change energy piles

As a famous underground heat transfer structure, energy piles have been widely used in geothermal energy development. However, the effect of the cyclic temperature field on the ultimate load capacity of a single pile is substantial. In this study, model piles were poured using a phase change energy storage concrete based on Gum Arabic with polyethylene glycol 600. An indoor modeling test was designed to compare the phase change energy pile (GPEP) with the traditional energy pile (TEP). The ultimate bearing capacity of a single pile is obtained through theoretical formulas and static load tests to compare the bearing performance superiority of GPEP over TEP comprehensively. The response mechanism of GPEP to temperature changes was determined by evaluating the temperature change of the pile body, shear strength, water content of the soil facing the pile, thermally induced frictional resistance, and pressure exerted by the soil facing the pile. The results indicate that the single piles of GPEP increased the ultimate bearing capacity by 13.04 % (theoretical formula) and 13.70 % (static load test) compared to TEP. Due to the energy storage properties, phase change materials effectively restrict the temperature-drag response of energy piles. This study serves as a valuable reference for the practical engineering implementation of GPEP.

Comparative Investigation of Axial Bearing Performance and Mechanism of Continuous Flight Auger Pile in Weathered Granitic Soils

Axial bearing performance and mechanism of continuous flight auger (CFA) pile in weathered granitic soils, i.e., a widespread special soil in South China, were investigated by field test in this study. Load–settlement responses of four CFA piles were examined, and evolutions of shaft/base resistances were captured by ultra-weak fiber Bragg gratings (UWFBG) with a reflectivity ≤−40 dB. Performances of CFA piles were compared with those of a slurry displacement (SD) pile at the same site, thirteen pretensioned spun high-strength concrete (PHC) piles in the literature and empirical data in design code. Test results show that the ultimate bearing capacity of the CFA pile is highest among different pile types, and typically is twice that of the SD pile. Again, CFA pile produces the highest shaft resistances at 140 kPa and 153 kPa in two weathered granitic soils, while the base resistance of 3080 kPa is between those of the SD pile and the PHC pile. By field excavation, the superior mechanism of the CFA pile is suggested to avoid the formation of in-between bentonite layers and prevent preferential baseflow along fissures, both of which can weaken the soil–pile interface. Overall, this study provides fundamental data through UWFBG and explanations based on field observations which underpin the need for developing a design code specified for CFA piles in South China.

Theoretical Analysis of the Influence of Bearing Plate Position on the Bearing Performance of Soil around the CEP Antipull Force Double Pile

With the development of large-scale projects such as high-rise buildings, deep-sea platforms, bridges, etc., these construction facilities are affected by many factors such as environment and geological conditions, which put forward higher requirements for pile-bearing capacity. Compared with the straight-hole grouted piles, the CEP (concrete expanded-plate) piles have an increased bearing plate, which has stronger resistance to pullout under the action of axial tension. The location of the bearing plate is the main factor affecting the bearing capacity of a CEP pile. This study simulates and analyzes CEP double piles on ANSYS software (Ansys R19.0 versions) under ideal conditions, designs five types of model piles with different bearing plate positions, and divides them into six groups for simulation. Finally, a complete model of the two-pile system is established. It is obtained that when the bearing plate is in the same position, the longer the pile length above the bearing plate, the greater the ultimate bearing capacity of the CEP double piles; when the bearing plates of a double pile are at different positions, the antipull-force-bearing capacity of the double pile mainly depends on the pile with a smaller pile length above the bearing plate, and determines the calculation mode of a CEP double-pile antipull-force-bearing capacity at different bearing plate positions, so as to provide a theoretical basis for the design and application of CEP pile foundations in large building structures in the future.

Re-evaluation of machine learning models for predicting ultimate bearing capacity of piles through SHAP and Joint Shapley methods

Re-evaluation of machine learning models for predicting ultimate bearing capacity of piles through SHAP and Joint Shapley methods

Model test on thermo-mechanical properties of static drill rooted energy pile under long-term temperature cycles

Static drill rooted (SDR) pile emerges as a composite of a prefabricated pile and cemented soil. SDR pile technology was introduced into the energy pile design due to its high load-bearing capacity, excellent heat transfer performance and favorable stability. Indoor model tests were established to investigate the thermo-mechanical behavior of an SDR energy pile under long-term temperature cycles. It was found that the studied pile had better heat transfer performance and bearing capacity (50%) than the ordinary pile. After twenty long-term temperature cycles, Additional tensile and compressive stress were observed in the pile. The additional thermal stress in the pile initially increased and then decreased with the increasing depth of the pile. The stress fluctuation would not damage the pile material since it was maintained within the design value of concrete strength. The side friction of the pile gradually increased with the increasing cycle numbers. The cumulative settlement of the SDR energy pile was induced by temperature cycles and reached −0.155 mm (0.18% D) after 20 cycles, less than the ordinary pile. The first two cycles accounted for 53% of the total cumulative settlement, and cooling was the main factor causing pile top settlement. The ultimate bearing capacity of the SDR energy pile was decreased by 9% after 20 cycles. The investigation of the long-term thermo-mechanical behavior of the SDR energy pile provides a theoretical basis for its practical application. SDR energy piles are significant for the efficient use of shallow geothermal energy.

Limit equilibrium theory in calculating screw pile bearing capacity under compression

The problem of calculating the ultimate bearing capacity of a screw pile is studied using the limit equilibrium theory in this paper. Calculation methods for the critical screw pitch and the ultimate bearing capacity under two representative failure modes are proposed. Four key parameters affecting the ultimate bearing capacity are compared and analysed, and design optimisation suggestions are put forward. The results illustrate that the ultimate bearing capacity of the screw pile is mainly affected by the shear strength of the soil, the height of the screw thread and the screw pitch. When designing the screw pile, the height of the screw thread could be increased and the screw pitch reduced to some extent.

PERENCANAAN FONDASI TIANG BOR PADA TANAH LANAU UNTUK GEDUNG APARTEMEN 20 LANTAI

Foundation is the part of the construction that transmits the load of the superstructure supported by the foundation with its own weight into the soil and rock that lies below it. The purpose of bored pile foundation planning is to design the dimensions of the foundation in the apartment building, calculate the axial and lateral bearing capacity, calculate settlement, calculate the reinforcement used and calculate the cost required for the construction of the bored pile foundation. The bored pile foundation in the apartment building used a circular foundation with a diameter of 0,5 meters which has a depth of 21 meters and located on sandy soil. The axial end bearing capacity of the bored pile uses the Reese & Wright method with a calculated value of 70,450 tons and the ultimate pile bearing capacity of 451,766 tons. Lateral bearing capacity of a single pile using the Evans and Duncan method is 16,359 tons and the maximum lateral bearing capacity of the group is 36,809 tons and the maximum deflection value is 1,419 mm. The bored pile foundation based on the calculation results refers to SNI 2847:2013 concerning Requirements for Structural Concrete for Buildings, for longitudinal reinforcement using 7D19 reinforcement and for spiral reinforcement using D16-40 reinforcement. The budget plan for the foundation and pile cap is Rp. 10.704.000.000.

Revisiting the analytical solutions for ultimate bearing capacity of pile embedded in rocks

Revisiting the analytical solutions for ultimate bearing capacity of pile embedded in rocks

Mechanical behavior analysis and bearing capacity calculation of CFG pile composite foundation on coral sand site

Coral sand foundation formed by hydraulic fill often faces the problem of poor bearing capacity. This paper proposed for the first time to apply CFG pile composite foundation to coral sand sites to verify the feasibility of this scheme and understand its mechanical characteristics. Firstly, taking on-site coral sand as the research object, a pile sand interface shear test was conducted to clarify the mechanism of pile side friction. At the same time, the ultimate bearing capacity of CFG pile and its composite foundation was measured through in-situ static load tests. Then, based on the strength parameters of the pile sand interface revealed by indoor tests, numerical simulations were conducted to analyze the bearing characteristics of CFG piles and their composite foundations. Finally, a method for calculating the vertical bearing capacity of rigid piles in composite foundation considering interface parameters was proposed. The results showed that the bearing capacity characteristic values of single pile and composite foundation meet the design requirements; The interface friction angle and cohesion together increased the ultimate side friction by 64.41%; The load is mainly borne by the pile tip resistance, and the increase of the interface friction angle will make the proportion of the side friction load first increase and then decrease more obviously; The pile soil stress ratio first increased and then tended to stabilize as the interface strength increased. Compared with the field static load test results, the rationality of the calculation method for composite foundation rigid piles was verified. This study may have reference significance for the design and construction of coral sand foundation treatment in offshore island and reef projects.