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The analytical model for calculating the bearing capacity of a pile, presented in the commentary to STN 73 1002 - Pile Foundations, gives a recommendation to reduce the pile's length in the calculation of the shaft resistance. The recommendation is based on Caquot-Kérisel's theory. Especially in the case of embedded piles, reducing a pile's length in the calculation can cause the shaft friction of the embedded pile to be neglected, and the calculated resistance of the pile is thus significantly lower. The results of instrumented static load tests of embedded piles were analysed. The main aim of the study was to verify the validity of reducing the pile's length in the analytical calculation of the shaft resistance. The results of the static load tests analysed did not show any reduction in the shaft friction on the embedded part of the pile. In the form of a parametric study, the effect of reducing the pile's length in the calculation of shaft friction was analysed for different dimensions of embedded piles. [ABSTRACT FROM AUTHOR]

The high volume of vehicles at Simpang Joglo, which caused traffic congestion, became a particular focus for the government. The construction of the bridge on this railway line of PT. Wijaya Karya (WIKA) is located at KM 105+499 to KM 105 +772, with a bridge stretch of 272.80 m and a width of 14.1 m. The problems raised in this study include the effect of the implementation of bored pile work on the environment, whether the solution to the problem affects cost and time, and how much the carrying capacity of the bored pile is at this stage, using qualitative research methods and quantitative research methods. After observations and interviews with the community, it can be known that the bored pile foundation work on the Railway Elevated Line Construction Project between Solo Balapan - Kadipiro at KM 104 + 700 to KM 107 + 000 (phase 1) has several impacts that affect the work environment and the community environment, including noise, road damage, air pollution, land collapse due to drilling damage to tools, etc. From this impact, there are several solutions, including repairing road facilities, changing tools, etc. From the results of the analysis of the calculation of the bearing capacity of the foundation at Pier 11, a value of 28135.397 kN was obtained. The benefits of this research are that it can find out problems and solutions for work, know the impact on time and cost, and know the carrying capacity of a bored pile. [ABSTRACT FROM AUTHOR]

The evaluation of the bearing capacity of shallow or deep foundations is a major and traditional problem This article deals with the estimation and analysis of this bearing capacity but with a probabilistic method (statistics) therefore the main objective of this work is to do a probabilistic analysis. To answer and achieve this goal, the work has two lines of research: a theoretical one which brings together a bibliographical synthesis on the estimation of the bearing capacity of a pile by the in situ method (in place) such as the pressuremeter test and the second axis is experimental reinforced by a statistical analysis. The results of the pressuremeter test used in the evaluation (determination) of the bearing capacity of a pile considered as a deep foundation which actually represents the abutment of a rail bridge. An experimental study is underway for pressuremeter test on several sites. The geotechnical data comes according to a study of the project for the construction of a deep foundation for a bridge in the region of Tissemsilt in Algeria, after having defined the pressuremeter profile and estimated the bearing capacity by the pressuremeter method, the reliability of the results was tested. by a probabilistic (statistical) analysis using the normal distribution. [ABSTRACT FROM AUTHOR]

Loess soils cover approximately 10% of the Earth's land surface. Due to its honeycomb structure, this soil collapses under pressure and immediately settles when exposed to moisture. Using moisture and loading conditions prior to construction can have positive effects on the geotechnical properties of the soil and help to reduce its settlement. This study aims to investigate the effect of different installation methods of helical piles on microstructure of loess soils. A total number of 16 full-scale helical piles including single helix and double helix piles with spacing to diameter ratios of 1.5 and 3 were installed via wet and dry installation methods. These 3-m-long piles were installed at the site of Inche Borun, Golestan province, northeastern Iran. Pile static load tests were performed on a set of these piles to compare the effect of different installation methods. Furthermore, the behavior of Golestan loess was investigated by removing the soil in front of the other set of helical piles for element testing and SEM imaging. The results suggested that the combination of compressive installation load and water pressure increases the shear strength parameters of Golestan loess and accordingly, the bearing capacity of the installed helical piles. [ABSTRACT FROM AUTHOR]

Cyclic tests and finite-element method (FEM) analyses were used to study the effects of varying the type of pile, stirrup ratio and reinforcement technique—concrete infilling, steel fibers or deformed steel bars—on the seismic performance of prestressed high-strength concrete (PHC) piles. The failure modes, hysteretic performance, ductility, bearing capacity, stiffness degradation and energy dissipation capacity were observed and analyzed. The results show that the PHC piles were damaged by bending, and that the bearing capacity and ductility of the PHC piles increases with the reinforcement ratio of the prestressed tendons. It was found that adding concrete infilling into the hollow section improves the bearing capacity and hysteretic performance of the PHC piles, whereas the steel fibers have little effect. It was also found that the hysteretic loops of the PHC piles reinforced with deformed steel bars are fuller, and that the energy dissipation is good. An FEM analysis was used to simulate the nonlinear behavior of the PHC piles under cyclic loading, and the predictions agree relatively well with the experimental results. [ABSTRACT FROM AUTHOR]

Field pull out test results of 500 kV double-circuit line of Luping-Fule are presented in this paper to investigate the uplift bearing behavior of rock-socketed belled short piles. A calculation model of rock-socketed belled short pile has been proposed. During the initial stage of loading test, uplift load is shared by even section and bell of the pile, and the bell continues to bear uplift load after the lateral resistance of even section pile reaches the limit. A different performance has been found on the case of long belled pile. At the ultimate state, the uplift resistance provided by bell accounts for about 54.9% and 34.7% of the total uplift capacity for the 6.0 m long and 7.0 m long piles, respectively. Increasing pile length has been found to noticeably increase the ultimate uplift bearing capacity, while it has less effect on the displacement of pile top. The uplift capacity of even section pile is associated with the shear strength of rock mass around the pile, and the test results demonstrate that the ultimate resistance can be equal to the shear strength. The calculation method proposed in this paper is proven to be able to accurately predict the ultimate uplift bearing capacity of the rock-socketed belled short piles. [ABSTRACT FROM AUTHOR]

The horizontal stiffness of composite piles is an important factor influencing the horizontal bearing capacity of composite piles. However, this factor has been analyzed through field experiences rather than theoretically by other researchers. In this study, a calculation formula for analysis of this factor was deduced through an elastic-plasticity theoretical analysis. The formula was used to investigate influences of solidified soils on the horizontal stiffness and the bearing capacity of composite piles in accordance with stress mechanism under horizontal loads. Then, the differential equation of composite piles deflection under the combined stiffness was achieved. On this basis, a one-way cyclic loading test on six piles was performed on the site. Results demonstrate that solidified soil increases the combined stiffness of composite piles in the deformation process from elasticity to plasticity. The characteristic value and the ultimate value of single-pile horizontal bearing capacity in the composite piles are 1.81-2.62 and 2.00-2.25 times those of tubular pipes, respectively. When the length-diameter ratio of tubular pile is more than 27.5, the single-pile horizontal bearing capacity in the composite piles is less affected with the increase of length-diameter ratio of tubular piles. The accuracy of the theoretical analysis on the factor is further verified by the field test. The conclusions can serve as references for engineering design and further research of composite piles. [ABSTRACT FROM AUTHOR]

An analysis was carried out in this paper on the bearing capacity of pier pile and seismic performance rule when the low-pile cap is increased by 1 meter, 2 meters, and 3 meters. The bottom of the pile cap of pier no. 11 of Minjiang River bridge faces three “lows”: 7.6 meters lower than island, 4.6 meters lower than natural river bed, and 6.5 meters lower than low water level. The numerical simulation method is adopted to input three seismic waves of Wolong, Bajiao, and EL to evaluate the bearing capacity of pier and pile under strong earthquakes. Using the standard formula and numerical simulation method, it is observed that the bending moment and axial force of bridge pier show an insignificant change under different seismic waves when the pile cap is increased by 0–3 meters. With peak ground acceleration increased to 0.35 g, the vertical bearing capacity and flexural capacity of pier and pile gratify the requirements; however, the pile foundation will be subject to compression and bending damage. [ABSTRACT FROM AUTHOR]

Driven pile foundations may experience an increase in bearing capacity overtime after installation which is referred to as pile set-up or freeze. Field observations have demonstrated that pile set-up could be substantial and the evolution of pile shaft capacity may continue for an extended time after pile installation. This paper presents results of a series of pile load tests conducted on medium-scale steel and concrete pile foundations driven into marine sensitive clay in Gloucester, Ontario. The piles were tested instantly after driving to measure their initial bearing capacities, and were tested repeatedly over different elapsed times to study the evolution of pile shaft capacity over time. The excess pore water pressure around the pile was also monitored by a piezometer. The pile performance analysis was established by monitoring the shaft capacity of driven model piles over 1 month in soft marine clay. The average pile capacity measurements for both steel and concrete piles showed approximately 4.5-5.5 times increase in the pile capacity 30 days after initial driving depending on the type of the piles used. [ABSTRACT FROM AUTHOR]

Piles are usually made of steel, concrete, reinforced concrete or wood, used to enhance the ground's bearing capacity in order to enable the construction of deep foundations, also called pile foundations. However, the exact effect of the complex interaction between the piles and the surrounding soil has not adequately been investigated yet. Considering the increased application of the technique recently, further analysis is essential for achieving the highest economic and technical capacity. Using fewer piles or shorter piles and allowing greater distances between pile groups, results to reduced construction. However, other restrictions such as high groundwater level, bedrock depth and the limited size of the foundation are also to be considered. The issue of optimal pile layout is further investigated in the current paper employing Plaxis, a finite element software, for modeling purposes and considering axial loadings in granular soils. Results are shown and further discussed. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Compared with conventional piles such as the circle pile, the cast-in-place large-diameter pile (PCC pile) has many advantages: the lateral area of PCC pile is larger and the bearing capacity of PCC pile is higher. It is more cost-effective than other piles such as square pile under the same condition. The deformation of the PCC pile is very important for its application. In order to obtain the deformation of the PCC pile, a new type of quasi-distributed optical fiber sensing technology named a fiber Bragg grating (FBG) is used to monitor the deformation of the PCC pile. The PCC model pile is made, the packaging process of the PCC model pile and the layout of fiber sensors are designed, and the strains of the PCC model pile based on FBG sensors are monitored. The strain of the PCC pile is analyzed by the static load test. The results show that FBG technology is successfully applied for monitoring the deformation of the PCC pile, the monitoring data is more useful for the PCC pile. It will provide a reference for the engineering applications. [ABSTRACT FROM AUTHOR]

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 ( Q ) 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 Q 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 Q 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 ( R ), 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 Q 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. [ABSTRACT FROM AUTHOR]

This paper describes an analytical method for evaluating the bearing capacity of piles, installed with no soil excavation. It describes a process of pile insertion into soil and a method of pile side bearing capacity evaluation, based on a solution of the cylindrical cavity expansion problem. Analysis of analytical and test data shows the validity and applicability of the proposed method. [ABSTRACT FROM AUTHOR]

Cement fly-ash gravel (CFG) pile is a widely used ground reinforcement technique. This paper aims to address the mechanical characteristics of CFG composite foundation in consolidating saturated mine tailings (MTs) dam. The field static load tests were employed to explore the bearing capacity of the CFG composite foundation, and finite element (FE) models in three dimensions validated through comparison with experimental results were used to discuss the pile-soil stress distribution and pile-soil stress ratio of the CFG composite foundation. The results indicate that the distribution of earth pressure and pile stress is relatively homogeneous and stable over depth and load, while the development of CFG composite foundation bearing capacity is insufficient, in which the developed bearing capacity of CFG piles is less than 50% of its characteristic value. Additionally, compared with the laboratory model test results, the pile-soil stress ratio decreases with the increasing of the load in FEM results proved to better conform to the actual engineering conditions. Furthermore, the deformation modulus and thickness of cushion exert significant influence on pile-soil stress ratio and integral bearing capacity of CFG composite foundation. [ABSTRACT FROM AUTHOR]

The present study investigates the behaviour of plug on pile load capacity and effect of plug removal. The sand used as a foundation soil is poorly graded clean sand. It was prepared at different densities using a raining technique. To simulate the pile load test in the field, a new apparatus was manufactured. A driving–pressing system for pile installation was manufactured. The soil plug is removed by a device manufactured to remove the soil column entrapped inside the pipe piles during installation by driving and pressing devices. The present study focuses on the determination of effect of soil plug on the ultimate compression capacity of single open-ended steel pipe pile, and makes a comparison with closed-ended pipe pile. A new type of pipe piles is suggested; it is closed–open-ended pipe piles driven and pressed into sandy soil of different densities (medium and dense) in which axial compression load tests were performed on model piles. The pile end will be open to a predetermined depth in order to make pile penetration easy and closed at a distance in order to increase the pile base resistance. Twenty-four models of open-ended piles have been modified by closing the pile ends by a plate welded at a distance of 2D, 3Dand 4D(whereDis the diameter of the pile) from tip of the pile. These piles have been installed in sand by two types of installation, driving or pressing. It was concluded that the pile load carrying capacity in dense sand is several times greater than those in loose and medium sands, especially in the case of closed-ended or open-ended piles, since the pipe pile can produce external and internal skin friction in addition to end-bearing resistance that makes the total pile capacity close to that of closed-ended pile. On the other hand, the removal of soil plug decreases the pile load capacity. This decrease becomes apparent in dense sand. The decrease in load capacity is about 45%–63%, 55%–63% and 51%–79% in loose, medium and dense sands, respectively. Open-ended pipe piles behave as closed-ended, if the soil plug formed inside piles in a state of partial plug or full plug. The length of soil plug depends on the type of installation and relative density. For the type of pile proposed in this study, open-ended piles are closed with a plate welded at a distance of 2D, 3Dand 4Dfrom the tip of the pile, and the open part of the pipe pile has a limited length, which was found to be 3D. This length revealed the maximum pile capacity due to the development of both interior and exterior skin friction in addition to end resistance. In addition, at this length, the soil column is pressed inside the pipe and hence the soil was densified leading to increase the skin resistance. [ABSTRACT FROM AUTHOR]

Soil-cement mixed piles are widely used to improve soft subsoil. But in regions with high-salinity groundwater, the soil-cement is susceptible to deterioration. At present, however, the design code for soil-cement pile composite foundations does not consider the deterioration effect of soil-cement. The saltwater region in the Yellow River Delta of China is used as a case study. Based on early strength tests of soil-cement, a practical prediction method for the lifecycle bearing capacity of soil-cement piles is put forward, and the influence of deterioration on the settlement of composite foundations is studied using model tests and numerical simulation. The prediction method of pile bearing capacity considers the progressive deterioration of soil-cement, and it shows that the deterioration of soil-cement has a great influence on bearing capacity of mixed piles with an increase in age, and the loss ratio of bearing capacity quickly reduces with a decrease in pile diameter. The deterioration also increases the settlement of composite foundations. Furthermore, pile defects aggravate the deterioration effects of soil-cement piles on the settlement of composite foundations. [ABSTRACT FROM AUTHOR]

A bearing capacity estimation method for bridge piles was developed. In this method, the pulse echo test was used to select the intact piles; the dynamic stiffness was obtained by the impulse transient response test. A total of 680 bridge piles were tested, and their capacities were estimated. Finally, core drilling analysis was used to check the reliability of this method. The results show that, for intact piles, an obvious positive correlation exits between the dynamic stiffness and bearing capacity of the piles. The core drilling analysis proved that the estimation method was reliable. [ABSTRACT FROM AUTHOR]

Tan, H.; Jiao, Z., and Cai, Z., 2015. Long term field test on structure forces of sheet-pile wharf with barrier piles. Based on the first engineering application of new-type sheet-pile wharf with barrier piles, the field test has been conducted for 7 years. According to the long term field testing results, the structure forces of the wharf front wall and barrier piles have been obtained in different periods. The results have showed that the new wharf structure was effective for a large harbor basin, the maximum positive bending moments for both front wall and barrier piles appeared in dredging period, and the maximum negative bending moment appeared in operation period. The rebar stress of front wall was about twice larger than that of barrier piles. In order to make full use of the potential bearing capacity of front wall and barrier piles, the optimal design was to make them in the same stress level. The modified bending moment calculation method has been proposed based on the field testing data. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

To understand the mechanical properties of superlarge-diameter piles in complicated geologic conditions, the authors carried out centrifuge model tests that simulated the bearing characteristics of single rock-socketed piles that had different cover thicknesses and rock-socket lengths. Valuable results were obtained from the centrifuge model tests. The overlying stratum of a single superlarge-diameter rock-socketed pile shares a certain proportion of the upper load, so it is not wise to neglect its bearing capacity in this type of design. The shaft resistance and tip resistance did not work synchronously with an increase in the upper load. Shaft resistance was mobilized prior to tip resistance and carried the majority of the upper load when the rock-socket length exceeded three times the pile diameter. There is an optimal rock-socket length for a certain thickness of overlying stratum. A centrifuge test was performed to investigate the behavior of a pile group socketed in bedrock with an inclined surface. The load distribution in the pile group was not even, and piles that had longer rock-socket lengths shared more load than piles that had shorter rock-socket lengths. The inclined surface caused differential settlement under concentrated vertical loading, which might result in safety issues with the superstructure. [ABSTRACT FROM AUTHOR]

The article focuses on the method for evaluation of ultimate bearing capacity for a vibratory pile having acceleration data recorded during the tests. The simulation vibratory pile installation test was performed in the testing stand. Accelerations were recorded on the top of the simulation vibratory pile during the test. The static test was performed for the installed pile. After the review of rheological models of the base, the Smith rheological model was chosen for determination of bearing capacity of the vibratory pile as this model, the rigidity of the final element of the spring is modelled as the finite rigidity of the base. Between the base of the modelled pile and the soil, a finite interface element is used. The interface element transfers only compression but it does not transfer tension to the base rheological model. The general stiffness of spring's finite element in the chosen rheological model is determined from experimental data of the static pile test. During the modelling, the damping coefficients and the ultimate displacements (responses) of the pile's shaft and base, to which the friction element became active, were determined so that the modelled pile accelerations and displacement (response) would coincide as much as possible with measured accelerations and their calculated response. The modelled and measured accelerations and responses showed high similarity. [ABSTRACT FROM AUTHOR]

The concrete-cored deep cement mixing (DCM) pile is a new kind of composite pile created by inserting precast core pile into the DCM column socket and has only been used in a few projects to date. The bearing mechanism of concrete-cored DCM pile composite foundation has not been investigated systematically. In this paper, plate load tests (PLT) on single pile composite foundation were conducted in Nanjing-Changzhou expressway, Xinhua district in Jiangyin city and Nanjing surrounding (NS) expressway. Following the results of the PLT, a comparison of ultimate bearing capacity between composite foundation reinforced by concrete-cored DCM pile and DCM column was made. During the PLT process, the vertical stress of surrounding soil and DCM column socket was measured using pressure cells. The vertical stress of precast core pile was obtained using steel stress gauge welded onto the reinforcement. Based on the vertical stress of surrounding soil, DCM column socket and precast core pile, the skin friction and load sharing ratio were obtained. The variation in surrounding soil properties depending on the installation of concrete-cored DCM pile was also analyzed using the results from cone penetration tests (CPT) taken in NS expressway. With the analysis of results for stress tests and CPT, the bearing mechanisms of composite foundation reinforced by concrete-cored DCM pile are obtained. [ABSTRACT FROM AUTHOR]

Development of an effective countermeasure for existing bridge foundations subjected to the influence of riverbed excavation in Thailand is the main objective of this research. Due to the riverbed soil excavation for the utilization in construction works for many years, the level of riverbed of the Mae Nam Ping River has been considerably decreased, resulting in reduction of embedment lengths of piles for many bridge foundations. Erosion was not a cause of the lowering of the riverbed. Reductions of bearing capacity due to the lowering of riverbed soil is the main cause of bridge pile foundation settlements or collapses at present. In order to prevent the damages of existing bridge pile foundations caused by the riverbed soil excavation, a reinforcement method using sheet piles called "Sheet Pile Wall (SPW) reinforcement" is proposed in this paper. The proposed SPW reinforcement method consists of 2 simple steps without new additional piles or any modifications of existing structures. Firstly, sheet piles are constructed surrounding the existing problematic bridge pile foundation. Finally, the empty space inside the SPW is filled with sand or other porous materials such as crushed concrete. In order to investigate the performance of the proposed SPW reinforcement method, series of load tests on model pile foundations in dry sand were carried out. The experimental results show that the proposed SPW reinforcement method is very efficient and promising. Numerical simulation of an experiment using FEM was also carried out to get more insight into the mechanism of the SPW method and validate the proposed SPW method. [ABSTRACT FROM AUTHOR]