Ultimate Bearing Capacity Of Pile Research Articles

Simulation of Vertical Bearing Capacity for PHC-Steel Composite Pile

PHC-Steel Composite Pile is a new kind of piles combined by PHC pile in the upper part and Steel pile in the lower part. PHC-Steel composite pile has the advantages of corrosion resistance and good penetration properties over the traditional piles. However, one of the problem of PHC-Steel composite pile is the determination and computation of the vertical bearing capacity, which is very important for the safety of construction based on the piles. The traditional method can not be applied directly to calculate the vertical bearing capacity and the load transfer mechanisms were not investigated. Therefore, the design of composite pile is lack of mechanism basis. This paper performed simulation research on the PHC-Steel composite pile withe the software FLAC3D, based on geological conditions of the Yangtze River region of Zhenjiang Yangzhong. The vertical distribution of displacement field, the ultimate bearing capacity of pile, the micro strain were simulated by using the FLAC3D finite difference software. The contact between pile and soil were simulated by establishing contact surfaces. The ultimate bearing capacity of PHC- pipe piles was discussed, which provides the basis for design and analysis of PHC- steel pipe composite pile project.

Mechanical behaviors of SD and CFA piles using BOTDA-based fiber optic sensor system: A comparative field test study

Abstract Screw displacement (SD) pile and continuous flight auger (CFA) pile are two similar deep foundation technologies, and new developed SD piles are used for the first time in Anhui Province, China. In order to investigate the differences of their mechanical behaviors under the load, field static load tests were performed. The distributed strains along the full length of piles were measured using fiber optic sensor (FOS) system based on Brillouin optical time domain analysis (BOTDA) technology. The axial fore, shaft resistance and tip resistance were calculated using the measured axial strains according to the stress calculation method. Thereby, the load transfer mechanism and bearing capacity of SD and CFA piles were compared. The test results indicate that FOS system is an alternative method to measure the mechanical behaviors of the pile. When the ultimate load exerted on the pile top is reached, the pile tip force of SD pile is about 7.8% of the total load, which means that SD pile works as an end bearing friction pile. The ultimate bearing capacity of SD pile is 66.7% higher than that of CFA pile in this case study. The change of stress state of soil element induced by pile installation shows that the densification and shear strength improvement of surrounding soil is the main reason why the bearing behaviors of SD pile is better than that of CFA pile.

Bearing Capacity of the New Composite Foundation with Discrete Material-Concrete Compound Piles

In order to solve the bulging deformation and fracture at the top of widely used gravel piles in treating ground consolidation, a new, optimized composite foundation form was proposed. The composite foundation was constructed using discrete materials and concrete piles. Additionally, various parameters of this new composite foundation were analyzed, including foundation forms, construction technologies, bearing mechanism and failure mode. By applying cavity expansion theory, the Vesic cavity spreading pressure of the discrete material-concrete pile is solved as a polar axis symmetric problem on the basis of Mohr–Coulomb yield criterion. Then the computing formula for the ultimate bearing capacity of the discrete materials-concrete pile is elicited when the internal friction angle of soil in the piles is φ = 0 and φ ≠ 0. Finally, the ultimate bearing capacity value of the composite foundation is acquired through analytic calculation and numerical simulation. Finally, it is found that the calculation result is 14.4% lower than that of the simulated result, which is within the acceptable accuracy range and therefore proves the accuracy of the analytic calculation method for bearing capacity of the new composite foundation.

Experimental Study on the Behavior of X-Section Pile Subjected to Cyclic Axial Load in Sand

X-section cast-in-place concrete pile is a new type of foundation reinforcement technique featured by the X-shaped cross-section. Compared with a traditional circular pile, an X-section pile with the same cross-sectional area has larger side resistance due to its larger cross-sectional perimeter. The behavior of static loaded X-section pile has been extensively reported, while little attention has been paid to the dynamic characteristics of X-section pile. This paper introduced a large-scale model test for an X-section pile and a circular pile with the same cross-sectional area subjected to cyclic axial load in sand. The experimental results demonstrated that cyclic axial load contributed to the degradation of shaft friction and pile head stiffness. The dynamic responses of X-section pile were determined by loading frequency and loading amplitude. Furthermore, comparative analysis between the X-section pile and the circular pile revealed that the X-section pile can improve the shaft friction and reduce the cumulative settlement under cyclic loading. Static load test was carried out prior to the vibration tests to investigate the ultimate bearing capacity of test piles. This study was expected to provide a reasonable reference for further studies on the dynamic responses of X-section piles in practical engineering.

Assessment of CPTU and static load test methods for predicting ultimate bearing capacity of pile

ABSTRACTFor the static pressure pile, the most important is to determine the standard value of ultimate bearing capacity of single pile. At present, the bearing capacity of pile foundation is usually determined by the cone penetration test (CPT) test. The empirical formula was used in practice, but the effect of excess pore water pressure generated in the penetration on the measured cone-tip resistance and side friction is neglected. In this study, based on the field test results at Fengyu playground at Yancheng Institute of Technology by CPT and CPTU methods, the bearing capacity of pile was predicted by the standardized methods, the LCPC (France method) and CPTU direct prediction methods. The prediction was also compared with the results by the static load test method. The prediction accuracy of the CPTU method was then discussed as well. The results reveal that the accuracy of the CPTU method was the highest, which was consistent with the results obtained by the static load test method. It is the best method and worthy of being applied for predicting bearing capacity of piles in engineering applications.

Comparative study of Y-shaped and circular floating piles in consolidating clay

Although engineers often make use of pile geometry to improve the axial load capacity of piles, geometrical effects on floating piles in consolidating clay are still not fully understood. This paper reports two centrifuge model tests to investigate the responses of a Y-shaped pile and a circular pile subjected to an induced dragload and applied axial loads. Three-dimensional numerical back-analyses were performed considering the elastoplastic slip. The Y-shaped and circular piles developed similar downdrag, but the dragload induced on the Y-shaped pile was larger than that induced on the circular pile. As the axial load increased, the neutral plane shifted upward along a nonlinear path, of which the gradient of the Y-shaped pile was gentler. The ultimate bearing capacity of the Y-shaped pile was 1.73 times that of the circular pile. The dragload on the Y-shaped and circular piles was eventually eliminated at approximately 0.56 and 0.83 times the corresponding ultimate pile capacities, respectively. Three flanges of the Y-shaped pile “hung-up” adjacent soil that settled together with the pile shaft. The lateral extent of vertically nonuniform trapped soil decreased with increasing axial load. Even though the Y-shaped and circular piles encountered a similar serviceability limit state, Y-shaped pile had advantages in bearing capacity.

Axial Pile Capacity Prediction Obtained from Environmental Friendly Jack-In Piling Test on Clayey Soil

Jack-in piling is environmental friendly system enabling placement of the pile into soil layer with minimum disturbance. It works with very low noise, low vibration, allows piling in confined area, relatively very fast in term of installation rate, better quality control and very fast in mobility. The main issue regarding the pile is bearing capacity; the ability of the pile to withstand axial load without failure. This study attempts to find the correlation between jack-in force and ultimate pile bearing capacity. The result of 5 piling record on clayey layer soil indicates that there is a good correlation between jack-in force and empirical ultimate pile bearing capacity.

Effect Of Number Of Pile In Pile-Raft System In Organic Clay

In the valley area of Imphal in Manipur, organic clay are often encountered in the substrata of the soil which often creates problem in construction. These soils are characterized by low bearing capacity and high compressibility. A pile-raft foundation can be used to reduce the settlements caused by concentrated building loads. This study is mainly aimed to study the influence of spacing of piles and raft width on the behavior of the pile raft foundation in organic clay. Tests were conducted on rafts of size 100x100mm and 200x200mm of thickness 2mm. The numbers of piles were varied at 1, 4 and 9 and from the test results the ultimate bearing capacity of Piles will be increased and the settlement of Pile is reduced as the diameter of Pile increases. It is obtained that the settlement in the pile group standing alone are fast in settling in the beginning and reduced after some loading, but in case of raft alone slow settlement is observed.

Comparison between empirical and experimental ultimate bearing capacity of bored piles—a case study

In this paper, several pile load tests are conducted for the evaluation of the actual axial compressive bearing capacity of bored piles casted beneath rear crane beams in Shahid Rajaee Port Complex Development Project (SRPCDP) in south of Iran (case study). Different methods of pile load test interpretations are employed to achieve the actual bearing capacity of piles. Moreover, the result of pile load tests are compared with empirical relations based on American Petroleum Institute (API) and American Association for State Highway and Transportation Officials (AASHTO) recommendations. Undrained parameters for cohesive layers and SPT-N value or relative density of cohesionless materials are employed for the estimation of the bearing capacity based on API and AASHTO proposals. It can be observed that in most of cases, the empirical prediction based on API and experimental data are coherent. This coherency is more obvious when the pile tip is overlain on a sandy layer. Hence, notwithstanding the common use of API recommendation for the steel offshore pile design, it can also be employed for the design of bored piles.

Developing a hybrid PSO–ANN model for estimating the ultimate bearing capacity of rock-socketed piles

Rock-socketed piles are commonly used in foundations built in soft ground, and thus, their bearing capacity is a key issue of universal concern in research, design and construction. The accurate prediction of the ultimate bearing capacity (Qu) of rock-socketed piles is a difficult task due to the uncertainty surrounding the various factors that affect this capacity. This study was aimed at developing an artificial neural network (ANN) model, as well as a hybrid model based on both particle swarm optimisation (PSO) and ANN, with which to predict the Qu of rock-socketed piles. PSO, a powerful population-based algorithm used in solving continuous and discrete optimisation problems, was here employed as a robust global search algorithm to determine ANN weights and biases and thereby improve model performance. To achieve the study aims, 132 piles socketed in various rock types as part of the Klang Valley Mass Rapid Transit project, Malaysia, were investigated. Based on previous related investigations, parameters with the most influence on Qu were identified and utilised in the modelling procedure of the intelligent systems. After constructing and modelling these systems, selected performance indices including the coefficient of determination (R2), root-mean-square error, variance account for and total ranking were used to identify the best models and compare the obtained results. This analysis revealed that the hybrid PSO---ANN model offers a higher degree of accuracy compared to conventional ANN for predicting the Qu of rock-socketed piles. However, the developed model would be most useful in the preliminary stages of pile design and should be used with caution.

Determination of Ultimate Pile Bearing Capacity from a Seismic Method of Shear Wave Velocity in Comparison with Conventional Methods

The seismic method in the ultimate bearing capacity of piles based on shear wave velocity measurement is a new technique in geotechnical engineering design. In this study, the value of shear wave velocity, Vs is being successfully used to formulate a theory to determine the ultimate bearing capacity of piles. This theory is adapted from the ultimate bearing capacity of shallow foundation proposed by Keceli. Keceli’s formula is adapted by equating the pile tip vertical resistance of the seismic formula to the end bearing capacity of the pile tip for each layer. The sum of half the vertical resistance of each layer is then equated to the total shaft resistance of the pile. The end tip is then added to the total shaft resistance to give the total ultimate pile bearing capacity of the pile. This study was conducted at three sites, two sites of residual soil located in Malaysia and one site of alluvial soil situated at Collierville, Tennessee, USA. The results of the adapted seismic formula were compared with the static pile bearing capacities calculated using conventional methods proposed by Meyerhof for the SPT-N values and the Schmertmann, Bustamante and Gianeslli method for the SCPTu values. The percentage error in the ultimate bearing capacity of the piles between the adapted seismic and the conventional methods for all the sites were found to be -4.77%, -3.01% and -0.93% at Hulu Langat, Mutiara Damansara and Collierville sites respectively.

A Study of PHC Pipe Pile Vertical Ultimate Bearing Capacity Calcula-tion Method and its Numerical Simulation Analysis

According to the PHC pipe pile design of Xinwan Plaza, Huaiyuan, Anhui and pile test results of static sounding method and experience method using the ultimate bearing capacity of single pile are calculated, considering the effect of soil plug the influence of vertical ultimate bearing capacity of single pile, and the formula for calculating the lateral resistance and end resistance, static sounding method and the correction formula to calculate the bearing capacity calculated results was coincident with the results of test pile. Combining with the project of Xinwan Plaza, Huaiyuan, Anhui, through the static load test, a study of the load transfer mechanism of PHC pipe pile, analyzes the vertical load, the change rule of the settlement of pile body and pile and the use of finite difference software FLAC3D simulation of the PHC pipe pile static load test, the simulation results agreed with the measured load-settlement curve.

Prediction of pile bearing capacity using a hybrid genetic algorithm-based ANN

The application of artificial neural network (ANN) in predicting pile bearing capacity is underlined in several studies. However, ANN deficiencies in finding global minima as well as its slow rate of convergence are the major drawbacks of implementing this technique. The current study aimed at developing an ANN-based predictive model enhanced with genetic algorithm (GA) optimization technique to predict the bearing capacity of piles. To provide necessary dataset required for establishing the model, 50 dynamic load tests were conducted on precast concrete piles in Pekanbaru, Indonesia. The pile geometrical properties, pile set, hammer weight and drop height were set to be the network inputs and the pile ultimate bearing capacity was set to be the output of the GA-based ANN model. The best predictive model was selected after conducting a sensitivity analysis for determining the optimum GA parameters coupled with a trial-and-error method for finding the optimum network architecture i.e. number of hidden nodes. Results indicate that the pile bearing capacities predicted by GA-based ANN are in close agreement with measured bearing capacities. Coefficient of determination as well as mean square error equal to 0.990 and 0.002 for testing datasets respectively, suggest that implementation of GA-based ANN models as a highly-reliable, efficient and practical tool in predicting the pile bearing capacity is of advantage.

Numerical Analysis of the Mechanical Properties of Batter Piles under Inclined Loads

AbstractA three-dimensional elastic-plastic finite element model based on the elastic-plastic constitutive relation of the non-associated flow Mohr-Coulomb criterion is constructed to analyze the influence of inclination angles of loads and piles on the mechanical properties of batter piles under inclined loads. The results indicate that (1) the stiffness of batter pile depends on both its axial and horizontal stiffness under a smaller inclined load and does not become maximum under an axial force because of the existing stiffness balance in the axial and horizontal directions. (2) The relationship between the ultimate compressive bearing capacity of batter pile and the load inclination angle exhibits an M shape. The peak of this capacity appears near a small load inclination angle rather than under axial load. (3) The stiffness and bearing capacity of batter pile increase with pile inclination under positive inclined loads, whereas the results show the opposite behavior under negative inclined loads. (4)...

Limit analysis of vertical anti-pulling screw pile group under inclined loading on 3D elastic-plastic finite element strength reduction method

Based on the functional theory, catastrophe theory, simultaneity principle and the idea of strength reduction method (SRM), the bearing capacity functional and SRM of pile group foundation were established, and the criteria of ultimate load and the concept of safety storage coefficient (CSS) were advanced. The inclined ultimate loads by the static loading test, load increment method (LIM) and SRM are compared. Theoretically, the ultimate load of piles does not change with the loading levels when it is calculated by SRM. When the one strength reduction parameter is applied in the calculation boundary, there are calculating errors because the bearing capacity action of soils happened in the finite zone. The inclined loadings are 108, 132 and 144 kN, and SSC are 1.07, 0.94 and 0.79, respectively, so the calculation values of ultimate loads are about 115.56, 124.08 and 113.76 kN, respectively. The error between calculations and observation values is less than 6%. But the error between calculations of LIM and observations is 20%. Because of the effect of inclined loading, the push-rotation phenomenon of screw pile group appears. Under this testing, the ultimate bearing capacity of piles is mostly determined by the horizontal ultimate bearing capacity, and the effect of the vertical component of inclined load should also be considered.

The Review on the Modified Exponential Model in the Fitting of Loading-Settlement Curves of Single Pile

According to optimized fitting analysis for measured data in static load test of 22 different types of single piles, a new modified exponential model was proposed by authors in this paper. In comparison between the hyperbolic model and the integrated exponential curve model, the correlativity coefficients R of the modified exponential model were over 0.996. The fitting effect of the model of proposed in this paper is better than that of other models above-mentioned. The deviations between fitting and measured data in static load test for single pile was small, especially, in the tail pasts of fitting curves, the mean deviations of 2 test pile given in the paper are 1.61% and 1.99% respectively. The modified exponential model can be better described Q-S curves of single piles. It can be used to better evaluate the ultimate bearing capacity of single piles.

Determine the Stress Calculating Mode of Sliding Failure of Soil Mass under the Push-Extend Multi-under-Reamed Pile

Through the analysis of the sliding failure form of soil mass under the bearing push-extend reamed of Push-extend Multi-under-reamed Pile, in the paper, the law of coulomb-Mohr is used to establish a stress function and the theory of the sliding line is used to establish Prandtl regional stress field, which determines the stress calculating mode of soil mass and provides a theoretical basis for a further study of this type of pile ultimate bearing capacity of soil mass.

Research on Settlement and Bearing Capacity of Y-Section Pile Considering Abnormality Effect

The side friction of Y-section pile is non-uniform distributed along its inverted arch arc, the load - settlement law of Y-section pile distinguishes to the traditional piles' as there is abnormality effect of side friction. Computation theory of settlement and ultimate bearing capacity needs to be studied. Calculate the settlement under different loads based on the model of skin friction, ultimate tip resistance and additional stress coefficient, and then predict ultimate bearing capacity by loads-settlement laws, the theoretical values of settlement and ultimate bearing capacity are in good agreement with the results of Static load test. The influences of five variables R, θ, δ, s, and L on settlement of Y-section file are analyzed, the settlement of Y-section pile under the constant load decreases with the increase of R, δ, s, δ and increases with the increase of θ. The influences of Relevant parameters on ultimate bearing capacity are also analyzed, the ultimate bearing capacity of Y-section pile decreases with the increase of θ and increases with the increase of R, δ, s and L.

The Unified Solution of Gravel Pile Limit Bearing Capacity of Single Pile Composite Foundation

Based on the compaction effect of the gravel pile, the thick-walled tube model is established. Considering the gravel pile and pile materials with different properties of tension and compression of soil pile in the process of expansion, the influence of intermediate principal stress to improving the bearing capacity of foundation in the process of expansion, we use the planar axisymmetric double shear unified strength theory and present a gravel pile ultimate bearing capacity of single pile composite foundation unified expression. The theory study of gravel pile composite foundation and engineering practice has a certain guiding significance.

Axial Force Analysis of the Single Pile Based on FLAC3D

Complex interaction mechanism of pile and soil, pile load transfer analysis is difficult. On the basis of analyzing the load transfer mechanism of the friction pile, using the FLAC3D analysis on the initial ground stress state of equilibrium , axial load under the action of pile axial force and displacement, got the ultimate load bearing capacity of single pile and the stress of the contact surface. Analysis results show that the load and displacement in a certain stage into a proportional relationship. Also shows that simulation is feasible and provide a reliable method for the analysis of pile groups.