Pile Group Efficiency Research Articles

Review Kapasitas Daya Dukung Dan Tinjauan Waktu Pelaksanaan Bore Pile Pada Pembangunan Jembatan Jalan Bebas Hambatan Binjai Pangkalan Brandan

In the Sei Wampu Bridge work project, Binjai Pangkalan Brandan carried out bore pile foundation installation work at the A2 foundation point with a total of 21 piles. Review of the bearing capacity of bore pile foundations using Analysis from Meyerhof (1956) and the Converse-Labarre Formula method for the calculation of pile group efficiency. The time of completion of work based on the time schedule plan is 125 calendar days. This research conducted a review using the Critical Chain Project Management (CCPM) method to obtain time efficiency, so that the project can be carried out on time.
 From the results of analysis and discussion, it was obtained that the largest foundation carrying capacity was the result of laboratory data using method C. Significant differences in results were obtained, especially laboratory data due to the correlation value used in each method. The result of calculating the bearing capacity of the foundation based on the method of Luciano Decourt (1987) using N-SPT data is 287,600.76 kN; Meyerhof's (1956) method using N-SPT data is 265,062.68 kN; a combination of Meyerhof's method (1976), Vesic's method (1977); the combination of the Vesic method (1977), the Coyle and Castello method (1981) and the results of foundation carrying capacity analysis using the All Pile program is 41,159.85 kN.
 The Critical Chain Project Management method is defined as the longest chain of interrelated events, where the linkage lies in the work or resources that are interconnected with each other, by cutting 50% of the duration of the work and replacing it as a buffer. The time comparison obtained from the calculation results using the CCPM method obtained a time efficiency of 116 days with a work time difference of 7.2% or about 9 days from the existing duration of the previous 125 days, while to compare the results of the CCPM method, calculations were carried out based on realization for 97 days, where the realization results were smaller than using the CCPM method and time schedule plan.
 Keywords : Bore pile, Carrying capacity, Time review

PERENCANAAN PONDASI GERBANG TOL KUTANEGARA PROYEK TOL JAKARTA-CIKAMPEK II BERDASARKAN DATA CONE PENETRATION TEST (CPT)

The Jakarta Cikampek II Toll Road has several toll gates that require an analysis of the substructure against the load from the upper structure, one of them is the Kutanegara Toll Gate. The design of the substructure (foundation) is calculated based on upper loads and reactions from the superstructure. This study aims to analyze the bearing capacity of the deep foundation due to the reaction of the upper structure. As a result, this analysis ensures the safe condition of the infrastructure system. The method of this study use bearing capacity analysis based on the Cone Penetration Test (CPT) investigation with the Schmertmann and Nottingham Approach which is combined with the calculation of pile group efficiency using the Converse-Labarre formula. Based on the results of a soil investigation using CPT, the subgrade is clay soil at a depth of 0-10m with a qc value of 30-160 kN/m2 with a γ value of 18-20 kN/m3 and a cohesion of 50 kN/m2. The bearing capacity result at a depth of 10m reaches 428.71 kN. The pile configuration uses 2x2 piles with a diameter of 40cm and a pile cap size of 2m x 2m. The maximum Pu describes 193.6 kN, this value is still less than the bearing capacity of the pile which means the safety condition. This research is expected to be a reference for the analysis of the bearing capacity of the bottom structure for related toll gate designs.

Comparison of Structure Design Between Bored Pile Foundations and Pile Foundations (Case Study: Industrial Worker I Batang Flower House Construction Project)

Field surveys and laboratories found dense soil layers up to a depth of 14 m, so an alternative to drilled pile or pile foundations was used. This study aims to compare the pile and drilled pile foundation plans with the same soil data, loads, and dimensions. Analysis by calculating the pile foundation plan compared to the drilled pile foundation so that the planning results are obtained, soil bearing capacity, pile group efficiency, number of piles and drilled piles, RAB (budget plan), and drilled pile plans. Compared to 50cm square piles and 40×40cm square piles, the bearing capacity of a single pile (Qult) is 44.5 tons, and the bored pile foundation is 54.72 tons. The pile resistance (f) is 38.79 tons for piles with a diameter of 40 x 40 cm and 38.79 tons for drilled piles with a diameter of 50 cm. One pile's allowable pressure-bearing capacity (Pa) is 14.48 tons, and one drilled pile is 17.48 tons. The permissible tensile strength (Pta) for one pile is 11.64 tons, and for one drilled pile is 14.46 tons. The pile foundation requires 263 piles, and the bored pile foundation requires 258 piles.

Numerical study on pile group efficiency for piles embedded in cohesive and cohesionless soils

This paper aims to study the efficiency of pile groups with various numbers of piles and pile spacing. Axial loading tests on pile groups and also single piles were simulated using a three-dimensional finite element program to obtain the load-settlement curve and the ultimate bearing capacity of the piles which was later used to estimate the pile group efficiency. In this study, the piles were embedded in cohesive and cohesionless soils. The stress-strain responses of the soils and the concrete pile and pile cap were simulated using the Mohr-Coulomb and the linear elastic models, respectively. The numerical-based pile group efficiencies were then compared to those computed using the published formulas. To verify the findings, a series of parametric studies on pile groups embedded in stratified soil was performed where the parameters of the soils were derived based on a back analysis on a case study of a single pile axial loading test in South Jakarta. The results show that the axial pile group efficiency in cohesive soil would be less than or equal to one, whereas in cohesionless soil would be more than or equal to one, especially at pile spacing more than three times the pile diameter. Meanwhile, similar results as found in cohesionless soil were obtained for the stratified soil case.

Axial and Lateral Efficiency of Tapered Pile Groups in Sand Using Mathematical and Three-Dimensional Numerical Analyses

AbstractThis study presents a new mathematical equation for calculating the pile group efficiency in cohesionless soil under combined axial and lateral loading conditions, considering the tapering ...

Efficiency of pile groups in sand soil under lateral static loads

Efficiency of pile groups in sand soil under lateral static loads

Centrifugal model test of post-grouting pile group in loess area

In this paper, based on the in-situ post-grouting single pile of the Wuqi-Dingbian Expressway in China, the bearing performance of the post-grouting pile groups in loess area were studied with the use of the centrifugal model test. Taking into consideration pile spacing and number of piles, nine working conditions of single pile, 2 × 2 pile group with different pile spacing and 3 × 3 pile group were designed. The settlement, ultimate bearing capacity, pile side resistance, and end resistance ratio of pile groups with different pile spacing and number of piles before and after grouting were compared and analyzed. Finally, based on the change in the group efficiency obtained before and after grouting through the model test, the group efficiency of non-grouting pile groups in code was modified and applied to the calculation of the ultimate bearing capacity of the grouting pile groups. The results show that the group efficiency will decrease after grouting, and the bearing capacity of grouting pile groups increases gradually with the increase of pile spacing, and reaches the maximum when the pile spacing is 5d. The proposed bearing capacity calculation method of grouting pile group was validated by the model test results, and the calculation results generally agree with the model results, which is valuable for pile foundation designs.

Large-scale model tests of a single pile and two-pile groups for an offshore platform in sand

Estimating pile group efficiency for open-ended steel piles in small group arrangements is a challenging task for designers. This paper reports on the large-scale experimental campaign performed for the BorWin gamma offshore converter platform, which involved single piles and two-pile group systems on a scale of 1:10. The experimental works included installation, dynamic end-of-driving tests, dynamic restrike tests, and static load tests of a single pile and a pair of two-pile groups in densely compacted, artificially prepared homogeneous sand. The cone penetration test (CPT) profiles and the blow counts confirmed that the foundation systems are comparable to each other. The experimental results of the single pile system were compared with conventional design methods. Such comparison indicated that CPT-based methods and load-transfer methods are applicable at the considered model scale. The bearing capacity prediction obtained via the Case Pile Wave Analysis Program (CAPWAP) method is conservative with respect to the static capacity. A consistent setup effect can be detected by analyzing the complete dynamic loading session. The pile group efficiency for the given foundation system was found to be less than 1.0 at both very small and very large soil strains, while it equaled 1.0 at failure.

Static loading tests on small-scale pile groups

36 small-scale model tests in soft clay were conducted to research the performances of pile groups under rigid caps. The parameters studied were the effect of pile length, pile spacing, and the number of piles in a group. The group piles consisted of 4, 6, and 9 circular model piles of 16mm in outer diameter (D), while four kinds of the pile spacing between pile centers 3; 4; 5; and 6 times of the diameter and three types of the embedded pile lengths: 20D; 25D; and 30D were used. For comparison, three single piles with the same diameter and length were also tested under the same condition. The experimental results were discussed based on the following 3 points of view: the pile group efficiency, the settlement ratio, load distribution per pile location in the group pile. All discussion suggested that the pile number and pile spacing in a pile group caused a remarkable interactional effect between piles, whereas the settlement ratios are significantly affected by the pile length. Besides, each pile in the group of 6D pile spacing behaved more individually.

Numerical investigation on pile group efficiency embedded in soft clay

PurposeThis paper aims to investigate the pile group efficiency based on the load-settlement response in soft clay conditions, considering several pile configurations using a variable number of piles and pile spacing. The overall objective of the present paper is to provide further insight into the mechanical response of the pile group and aim at helping the engineers in taking a logical path in an iterative design process for pile group efficiency.Design/methodology/approachTo investigate the pile group efficiency, three-dimensional (3D) numerical simulations were performed using the finite-difference code FLAC3D.FindingsThe obtained numerical results are validated by comparing them to those of similar subgrade structure and in comparable geological conditions provided within the literature. The results indicated that although the bearing capacity of the pile group increases with increasing number of piles, the efficiency of the pile group is very important for a small number of piles. However, increasing of pile spacing has a positive effect on pile group efficiency depending on piles number and settlement level. The pertinence of the 3D numerical results of efficiency coefficient is judged by comparison with those obtained from the most popular formulas available in the literature.Originality/valueA predicted model is also proposed which is validated with the obtained numerical results to a better goodness of fit.

Analysis of nonlinear load-displacement behaviour of pile groups in clay considering installation effects

This paper presents an analytical approach for predicting the nonlinear load-displacement behaviour of pile groups consisting of displacement piles in normally consolidated and lightly overconsolidated clayey soils. The effects of squeezing and remolding on the soil around the piles caused by pile installation are reflected by the soil strength and shear modulus. The nonlinear load-displacement behaviour at the pile-soil interface is modeled by the load-transfer method with exponential load-transfer functions and the pile-pile interaction effects are reflected by the shear displacement method. A hybrid analytical method, incorporating the developed soil parameters and combining the load transfer method and the shear displacement method, is proposed for the problem considered. Four sets of centrifuge model tests, involving pile groups with different pile diameters, pile lengths and pile spacings, were conducted to verify the proposed analytical framework. The validity of the proposed method, the significance of the installation effects as well as the nonlinear behaviour of the pile groups are demonstrated by comparing the load-displacement curves from the centrifuge model tests with those from the proposed method and other relevant methods. Parametric studies are conducted to investigate the pile diameter, pile length, pile spacing and pile number on the stiffness efficiency of pile groups. The results indicate that increasing the pile diameter and length can effectively improve the stiffness efficiency and the load carrying behaviour of displacement pile groups.

Axial Resistance of Nondisplacement Pile Groups in Sand

When subjected to axial loading, the response of a pile in a pile group is different from that of an isolated single pile, all other factors being the same. Three-dimensional finite-element analyses were performed to study the response to vertical loads of nondisplacement pile groups in sand. The analyses were done with an advanced bounding-surface-plasticity constitutive model. The mechanical response of soil elements at various locations between the group piles was thoroughly investigated to reveal the underlying pile–soil–pile interaction mechanisms. Pile group efficiency was found to be a function of the pile head settlement, number of piles in the group, pile-to-pile spacing, and relative density of the sand. The effect of cap–soil contact on the pile group resistance development was also studied. For small pile groups, the group efficiency is close to or greater than 1 at settlement levels likely to be of interest in design.

Finite element analysis of the axial dynamic response and efficiency of pile groups

ABSTRACT Dynamic pile group effect can either increase or decrease the response of pile-supported structures. This paper presents the results of a three-dimensional finite element model of the pile-to-pile interaction that considers the effect of the surrounding soil to determine the dynamic stiffness and damping for vertical end bearing pile groups subjected to a vertical harmonic loading. The results were generated for a wide range of the dimensionless frequency parameter (ao ) for a 9 × 9-pile group with three different spacings: two-, four- and six-pile diameter. Both the stiffness and the damping showed an oscillatory behaviour with the dimensionless frequency parameter ao , as well as with the soil shear modulus. In addition, the group efficiency was determined as a function of the pile spacing and the soil shear modulus. The efficiency factor for the stiffness can be as high as 1.15 and as low as 0.7 and for the damping as high as 3.75 and as low as 0.4 as a function of the dimensionless frequency parameter ao .

Performance of X-shaped and circular pile-improved ground subject to liquefaction-induced lateral spreading

Liquefaction-induced lateral spreading has caused severe damage and significant financial losses in major earthquakes distributed globally. Groups of piling installed in liquefaction- and lateral spreading-susceptible ground has been proven to be effective in reducing lateral displacements, but further investigation into the soil-structure interactions is required to elucidate the mechanisms for mitigation of displacement. Further, it is hypothesized that cross-, or X-shaped, piling may provide improved restraint on lateral flow deformations due the destructive interference of flow imposed by their cross-section. In this paper, the effectiveness of groups of X-shaped and circular piles to mitigate lateral spreading ground was investigated to improve the understanding of the mechanisms for improvement. Shake table tests were carried out to examine and compare the efficacy and efficiency of X-shaped and circular pile groups. Design parameters including the pile arrangement (square vs. triangular spacing) and orientation (X vs. +) of the X-shaped piling were also taken into consideration. The results demonstrate that the X-shaped pile groups can significantly reduce the lateral displacement and the areal extent of liquefied sand flow as compared to the unimproved and circular pile-improved ground, and that the spacing and orientation play a critical role in the deformation response. These findings will help inform the design of pile-improved ground as well as the design of structural piling adjacent to submerged, liquefiable slopes.

Reliability analysis for Serviceability Limit State of pile groups foundation

The aim of this paper is to present an approach for the assessment of the Serviceability Limit State (SLS) reliability of pile groups foundation combining the Ultimate Limit State (ULS) reliability method of pile groups. To this end, the linear relationship between the ULS and SLS reliability indices is presented using the formulas for calculating the ULS and SLS reliability indices of single piles. Meanwhile, the influence of system effects, correlation coefficient between pile group efficiency and system effects (ρζ,χ), and limiting tolerable settlement (Slt) on the SLS reliability analysis of pile groups foundation is studied using pile load test data compiled for illustration. The results indicate that both the ULS reliability index (βG-uls) and the SLS reliability index (βG-sls) of pile groups foundation decrease with ρζ,χ, that powerful system effects can enhance the ULS and SLS reliability of pile groups foundation, and that βG-sls increases with Slt. the reliability level estimated by pile load test data is equivalent to that incorporating the SLS requirements with a certain value of Slt between 15 mm and 25 mm. For Slt larger than this value, Reliability-based Design (RBD) of pile groups foundation will depend on the ULS requirements, but, conversely, RBD will depend on the SLS requirements.

Development of Graphical Method of Pile Group Foundation Design

In the construction projects, a pile group foundation is often utilized. The group of bored piles is usually installed relatively close to each other and joined at the top by a pile cap to hold up the loads. In other hand, a fast estimation of the groups of piles capacities are needed in the preliminary design and in other conditions of projects, such as a supervisor of projects want to estimate the capacities of the group of piles. The purpose of this research is to study the correlations of groups of piles efficiencies with the number of piles and to compare the groups of piles capacities with the single piles capacities. Furthermore, this study is aimed to make a fast estimation of groups of piles capacities using proposed graphical method.The piles efficiencies are calculated using several methods, such as Simplified Analysis, Converse-Labare [1][2], Los Angeles Group, Seiler - Keeney, Das, and Sayed - Baker. In order to calculate the groups of piles capacities, the capacities of single piles are needed. The singles piles capacities are taken from graphical method proposed by Djarwanti et al. (2015a and 2015b). Three graphical methods utilized are derived from the Briaud et al. (1985) , Reese and Wright (1977), and Reese O’Neill method. Moreover, the proposed graphical method is applied in the case study. The case study takes palace in Graha Indoland Condotel Inside Yogyakarta Construction Project.The pile efficiency graph is recommended for this research since the value of pile efficiency could be easily taken. The value of pile efficiency for Graha Indoland Condotel Inside using Simplified Analysis, Converse - Labare, Los Angeles Group, Seiler – Keeney, Das, and Sayed – Baker are 1,75; 0,89; 0,94; 0,99; 4,00; 1,56 respectively. Meanwhile the value of pile group capacity with the value of pile group efficiency more than 1, showed that the pile group capacity based on the efficiency is bigger than the one based on single down pattern.

Analysis of laterally loaded pile groups in multilayered elastic soil

The paper presents a semi-analytical method of calculating the response of a pile group. The approach is based on tying the displacement at any point of the soil mass around a pile or group of piles to the displacements experienced by the piles themselves. This is done by multiplying the pile displacements by decay functions. Application of the principle of minimum potential energy and calculus of variations to the resulting displacement field formulation leads to the differential equations for the soil and piles. Solution of these differential equations using finite differences and the method of eigenvectors leads to the desired displacement field in the soil and deflection profiles of the piles. The method produces displacement fields that are very close to those produced by the finite element method at a fraction of the cost. To illustrate the ease of application of the method, it is then used to prepare pile group efficiency charts for some typical soil modulus profiles.

A finite element–based approach for predictions of rigid pile group stiffness efficiency in clays

This paper presents a finite element parametric study of several variables that affect the stiffness efficiency of rigidly capped pile groups with a view to developing a solution for preliminary design purposes. Previous empirical solutions from linear elastic work had identified a significant dependence of stiffness efficiency on pile group size and group spacing, and in this study, the effect of the pile length-to-diameter ratio, the compressibility of a stiff bearing stratum beneath the pile group and the depth below ground level to the stiff bearing stratum are also considered. Pile groups in a soft clay/silt are modelled using PLAXIS 3D Foundation in conjunction with a soil model that captures the stress dependency of soil stiffness. The trends from the soft soil study have been formulated into a set of equations which can be used to predict the stiffness efficiency of pile groups. This new approach captures more variables than previous simpler empirical prediction methods and performs better when applied to a database of 29 published pile group case histories.

Calculation Method of Super-Long Pile Group Efficiency in Clay

By comparison of existing formula of super-long pile group efficiency, combine the geometric feature of super-long pile group with large length-diameter ratio, simplify the original formula, then a suitable method which calculate the super-long pile group efficiency in clay has been proposed. Taking use of test data to verify the formula and results show that: the pile group efficiency from the method accords with the test value very well.

EVALUATION ON PILE GROUP EFFECT OF UNDER-REAMED DIAPHRAGM-WALL-TYPE PILES SUPPORTING HIGH-RISE TOWER

The Tokyo sky tree is supported by the pile group foundation using under-reamed diaphragm-wall-type piles with different sizes. This report describes the outline of the foundation design, the evaluation method in design of the effect of pile group and the analytical results of FEM. The results of this study are shown as follows: (1) The pile group efficiency is 0.58, 0.49 and 0.68 - 0.73 respectively under pushing, pulling and lateral load. (2) In case of the lateral loading, the pile group efficiency changed according to the direction of the load and the position of the piles.