Types Of Piles Research Articles

An experimental study and numerical modeling of laterally loaded regular and finned pile foundations in sandy soils

A significant objective in the design and implementation of capable and cost-effective pile foundations is the enhancement of their lateral capacity when lateral load is applied. This study offers a nonlinear 3D analysis of pile-soil interaction. The ways that piles behave are examined in this research, with a sequence of laboratory model tests conducted to develop p-y curves of laterally loaded finned and regular piles in multilayered sandy soil from Karbala city in Iraq. To clarify the effects of group interaction, pile type, pile group patterns, and spacing ratios were analyzed, and from the investigational tests, p-multipliers values were identified.

Vibrated Soilcement Piles

The article describes the vibration research effect of on strength increasing and soilcement density. Laboratory studies of vibration impact on soilcement during manufacturing on the basis of loam and sandy soils have been performed. The field experimental determination of deep high-frequency vibration influence on soilcement piles material characteristics has been fulfilled. The process of material shrinkage during manufacture has been investigated. The obtained results are introduced in the process of soilcement base and foundations placement. Field comparative tests with static compressive loading of three types of piles, including vibro-compacted soilcement piles, have been conducted. With the PLAXIS software system, and with it’s axisymmetric particular version, the relationship between loading and soilcement piles settling was established. Numerical stamp tests modeling with the help of the software system PLAXIS was performed to detect the soilcement vibration influence on the reinforced base deformation.

A Load-Testing Program on Large-Diameter (66-Inch) Open-Ended and PSC-Instrumented Test Piles to Evaluate Design Parameters and Pile Setup

This paper presents the results from a pile load testing program for a bridge construction project at Chalmette, Louisiana. The load testing includes three 66-in. spun-cast post-tensioned open-ended cylinder piles and one 30-in. square prestressed concrete (PSC) pile driven at four different locations along the bridge site in clayey-dominant soil. Both cone penetration tests and soil borings/laboratory testing were used to characterize the subsurface soil conditions. All test piles (TP) were instrumented with strain gauges to measure the load distribution along the length of the TPs and to measure the side and tip resistances, separately. Dynamic load tests (DLT) were performed on all TPs at different waiting periods after pile installations to quantify the amount of setup (i.e., increase in pile resistance with time). Case Pile Wave Analysis Program (CAPWAP®) analyses were performed on the DLT data to calculate the resistance distributions along the TPs. A static load test was performed only on the PSC pile and statnamic load tests (SNLT) were conducted on both pile types. Design parameters such as the total stress adhesion factor, α, and the effective stress coefficient, β, were back-calculated. The α values ranged from 0.41 to 0.86, and the β values ranged from 0.13 to 0.29. The load test results showed that SNLT overestimated the tip resistance as compared with dynamic and static load tests. Moreover, the pile tip resistance was almost constant during the testing period, and setup was mainly attributed to increase in pile side resistance with time.

An iterative method to infer distributed mass and stiffness profiles for use in reference dynamic beam-Winkler models of foundation piles from frequency response functions

Accurate characterisation of soil behaviour in Dynamic-Soil-Structure Interaction (DSSI) applications remains a significant challenge. Knowledge of the operational soil-structure interaction stiffness is important for applications ranging from earthquake engineering to offshore structures subjected to wind and wave loading. A number of methods have been derived to couple soil and structural properties using beam-Winkler models. One of the key drawbacks of these approaches is the disparity in predicted stiffness depending on the formulation chosen. Moreover, the contribution of soil mass in the dynamic motion of foundations is often neglected. In this paper, a method is presented that uses a Frequency Response Function (FRF) measured from a laterally-impacted pile to estimate operational stiffness and mass profiles acting along the pile. The method involves creating a beam-Winkler numerical model of the soil-pile system, applying a starting estimate of the soil stiffness and mass profiles and calculating weighting factors to be applied to these starting estimates to obtain a match between the measured FRF from the test pile and the calculated FRF from the numerical model. This paper presents the formulation of the iterative updating approach, and demonstrates its functionality using simulated experimental data of typical piles. Simulated data is used as it enables testing a wide range of circumstances including possible issues relating to the influence of the shape of the operational soil stiffness profile, soil density, effects of sensor noise and errors in damping estimation. The method may be useful in finite-element (FE) model updating applications where reference numerical models for soil-structure interaction are required.

Model Test Analysis of Excess Pore Water Pressure during the Sinking of a Pipe Pile with a Group of Holes

To investigate the law that governs changes in excess pore water pressure during the sinking of a pipe pile with a group of holes, excess pore water pressure is monitored during the process of sinking a pile between a pipe pile without holes and three types of pipe pile with holes based on model test. The influences of the time-space dissipation of excess pore water pressure are analyzed by considering the factors of sinking pile sequence and disposal hole mode. The variation rules for excess pore water pressure dissipation with time, depth, radial distance, and sinking pile sequence are also established during the process of sinking the pile. On the basis of comparison and analysis, the pipe pile with holes, which are penetrated in a radial manner, achieves the lowest excess pore water pressure peak and the fastest dissipation rate, which are the most favorable conditions for reducing the squeezing effect of the pile, and the best pile driving effect is achieved. Moreover, the results can provide a reference for the application of pipe piles with holes in engineering practice.

Energy-minimum optimization of the intelligent excavating process for large cable shovel through trajectory planning

Large cable shovel (LCS) is a complex engineering machine which is widely used in the open pit mine. It is characterized by low efficiency, high maintenance cost, and high energy consumption if manipulated by an inexperienced operator. To address these challenges, intelligentization could be a feasible solution. In this work, an intelligent excavation system is put forward and the corresponding energy-minimum optimization through trajectory planning of the optimal excavation is developed to realize the intelligentization of the LCS. Firstly, the excavating resistance acting on the dipper is modeled and the corresponding forces are analyzed. Then, by establishing the kinetics and dynamic models of the excavating process, the point to point (PTP) trajectory planning method is developed by setting the objective to minimize the energy consumption per unite volume material. Polynomial curves in different degrees are used in the PTP planning method and the optimal one is compared with the conventional S-curve in terms of the excavating performance. To explore the advantage of the proposed intelligent system and the corresponding trajectory planning based energy-minimum optimization method, four types of ore piles with different pile angles are compared with respect to the excavating performance. Results show that the larger the pile angle is, the later the maximum hoist power and crowd power will appear. Further, the effects on the excavating performance from different ore piles with complex terrains, including the flat type, concave type, convex type, and concave-convex type, are also studied in the numerical experiments. It is found that the trajectory based energy-minimum optimization method for the intelligent LCS can significantly save excavation energy as well as keep sufficient fill factor.

Axial load tests and numerical modeling of single-helix piles in cohesive and cohesionless soils

Small-diameter helical piles have been increasingly used in Western Canada, but there is a lack of research. The present research investigates the axial behavior of three types of small-diameter single-helix piles. Twenty-six helical piles were installed and loaded axially in a cohesive and a cohesionless soil sites. The limit state capacities are attained or extrapolated from the load versus displacement curves following Chin’s hyperbolic assumption. It is found that the hyperbolic assumption can closely predict the load versus displacement curves of the helical piles. The torque factor Kt was smaller for the larger pile shaft diameter in the homogeneous site, whereas in the heterogeneous site Kt is substantially affected by soil heterogeneity around the helix. To further understand the axial behavior of the tested piles, a beam-on-nonlinear-Winkler-foundation model is developed on the platform of the Open System for Earthquake Engineering Simulation, which is a finite element software framework for the computation of soil and structural systems. A parametric analysis is carried out to determine the best estimate of ineffective length, the equivalent shaft length where the shaft resistance is zero. It is shown that the numerical model with ineffective length of four helix diameters can properly simulate the axial load versus displacement behavior.

Field Tests on Influencing Factors of Negative Skin Friction for Pile Foundations in Collapsible Loess Regions

As a reliable building foundation form, piles are driven into collapsible soil layers to ensure stability of foundations. Because of water immersion, significant subsidence occurs on collapsible loess; then negative skin friction emerges on the pile surface, which eventually causes serious bearing capacity failures of pile foundations. Relying on water immersion tests of multiple piles in Lanzhou, China, this study analyzed the influencing factors of negative skin friction for pile foundations in collapsible loess regions. The main factors studied in this research are cumulative relative collapse amount, pile type, and change in loess collapsibility. The results demonstrate that the maximum negative skin friction has a negative correlation to the cumulative relative collapse amount, which is determined by the degree of difficulty of the emergence of the shear fracture surface. Owing to the compaction effect of the driven pile and surcharge load of the exploded pile, their negative skin frictions increase in varying degrees compared to that of the bored concrete pile. At the same test site, the changes in loess collapsibility are mainly affected by natural moisture content and dry density. Increases in both the natural moisture content and dry density reduce the loess collapsibility, immersion settlement rate, and negative skin friction of pile. The loess collapsibility can be improved by surcharge loading and pre-watering to reduce the adverse effect of negative skin friction on pile foundations in engineering applications.

Seismic behaviour of reinforced embankments in dynamic centrifuge model tests

A series of dynamic centrifuge model tests was conducted to investigate the effects of reinforcement on the seismic behaviour of hillside embankments consisting of sandy soils and resting on stiff base slopes. In total, three types of seismic reinforcements, namely, large-scale gabions, drainage-reinforcing piles, and ground anchors with pressure plates, were employed in the tests. The test results showed that: (1) the seismic performance of both lower and higher embankments was remarkably improved by installing large-scale gabions at the toe as they restrained the completion of the formation of sliding planes; (2) the installation of drainage-reinforcing piles at the embankment toe was rather effective in reducing the overall earthquake-induced deformation due to their high permeability and restraint effect against sliding displacement at the reinforced region; and (3) the embankments improved by ground anchors with pressure plates were not vulnerable to earthquake-induced damage due to their constraint effects even under high water table conditions. The improvement effects by the above-mentioned three types of reinforcements were presented by evaluating the global safety factors based on the results of a series of triaxial compression tests.

Three - dimensional Numerical Simulation and Validation of Load-settlement Behaviour of a Pile Group under Compressive Loading

Settlement of pile foundation is one of the controlling pile design parameters and its numerical simulation is one of the techniques widely used to predict the settlement behaviour of piles. This study was on the settlement behaviour of a pile group located in silty-sand deposits using the finite element (FE) approach which is based on the static pile load test. Three different types of analyses were investigated: (1) a linear elastic (LE) analysis in which the soil was assumed to be linear elastic, (2) a complete nonlinear analysis in which the soil adjacent to the pile shaft as well as the soil between the piles were modelled using the Mohr Coulomb (MC) or hardening soil (HS) model, and (3) a combined analysis in which the soil close to the pile shaft was modelled using the HS model while the soil in the remaining area was modelled using the LE or MC model. Numerical results obtained for the load-settlement behaviour of the pile group were validated using the popular RATZ analytical approach. The results of the FE analysis suggest that incorporating a nonlinear zone of soil close to the pile shaft as an interface and leaving the soil beyond this zone as linear elastic give a more reasonable estimation and a much better prediction of the pile group settlement. It is also suggested that for a typical pile group, a nonlinear interface of thickness equal to the pile diameter and extending from the pile shaft to the edge of the zone would be sufficient to capture the load transfer mechanism. The group settlement ratio predicted in this study is in good agreement with the findings made in the previous studies.

Longitudinal dynamic impedance of a static drill rooted nodular pile embedded in layered soil

ABSTRACTThe static drill rooted nodular (SDRN) pile is a new type of precast pipe pile with equally spaced nodes distributed along the shaft and wrapped by the surrounding cemented soil. In this paper, the longitudinal dynamic response of the SDRN pile embedded in layered soil is investigated with respect to the complexity of the pile body structure and the pile–soil contact condition. First, the shear complex stiffness transfer model is used to simulate the radial inhomogeneity of the surrounding soil. Then, the governing Equations of the pile–soil system subjected to longitudinal dynamic loading are established. The analytical solution for the dynamic response at the pile head is obtained by the shear complex stiffness transfer method and the impedance function transfer method. The degenerate case of the present solution is compared with the published solution to verify its reliability, and the complex impedance of the SDRN pile is compared with that of the precast pipe pile and the bored pile. Finally, a parametric study is conducted to investigate the influence of pile–soil parameters on the complex impedance at the pile head within the low frequency range concerned in the design of the dynamic foundation.

Classification of piles based on the results of low strain pile integrity tests – Case studies of selected piles in Lagos and Port-Harcourt, Nigeria

This paper presents the performance of low strain pile integrity test (LSPIT) based on data collected from selected piles in Lagos and Port-Harcourt industrial cities of Nigeria. Two types of piles...

Comparison between Theoretical and Practical Compression Capacities of Deep / Long Piles in Dubai

The rate of build high-rise buildings has accelerated rapidly over the last few decades, due to rapid urbanization and significant improvements in the field of the high-rise construction and technology. Many challenges were faced by the engineers in the design and construction of such buildings. One of the major challenges was the foundation systems, which are required to ensure the stability of the buildings. The common type of foundation system which is used in case of high-rise buildings is piles foundation system. Furthermore, in the most standards and codes of practice such as British Standard, the piles specifications and recommendations are stated for short piles which has a maximum depth range between 18.0 and 20.0 m. As well as, the theoretical equations for pile design, charts and different soil factors and parameters are based on old studies of short piles behavior. In this research, a comparison was conducted between the theoretical pile compression capacity which is calculated from the theoretical equations and the practical pile compression capacity which is derived from the results of pile’s static load test. The study covered three different cases of bored piles constructed in U.A.E. especially in Dubai. The piles used in this research have a depth ranging from 30.0 to 65.0 m. This type of piles is classified in this research as long or deep piles. A finite element model of each participated pile modeled by using PLAXIS 2D software, to judge between the practical and theoretical piles capacities. It was found that the theoretical compression pile capacity is 60–70% of the practical pile capacity with the same specifications (pile diameter and pile depth). As a conclusion of the results, the estimated piles diameter and depth in the concept design stage can be improved based on the results of this research.

Determination of the Engineering Properties of Submarine Soil Layers in the Bohai Sea Using the Piezocone Penetration Test

Due to the complexity of marine geotechnical engineering, the harsh operating environments, loose subsea soils, and high water contents, it is extremely difficult to obtain soil samples while maintaining the in situ conditions in offshore areas. The engineering properties of submarine soil layers in the Bohai Sea, China, were investigated in this work. The Wison‐APB borehole wireline piezocone penetration test (CPTU) system was used to conduct direct measurements of the cone tip resistance, sleeve friction, and pore pressure. The soil classification and the related soil properties, such as the undrained shear strength, sensitivity and overconsolidation ratio, shear strength profile at the investigation depths, and the single pile foundation bearing capacity, were estimated. Laboratory tests were also conducted in this work. The CPT test results show that there were large differences between the results of the CPT tests (Su) and the laboratory experimental results, which may be due to the compact silt and hard clay interbeds in some layers. The soil classification was determined according to the previous literature. The laboratory test results of the undrained shear strength, clay sensitivity, and the OCR match the CPT test results best when the parameters Nkt, Ns, and k are 15, 6, and 0.3, respectively. The final determination of the ultimate pile capacity depends on the soil’s mechanical properties and the pile type and design. The effects of wave surge and wind loading should also be taken into account in offshore engineering.

Influence of cyclic loading on performance of steel piles in sandy soil

This paper introduces an experimental study to clarify the response of steel pile models exposed to the cyclic loading. Thirty six models of two types of steel piles are tested (open ended pile and H-pile) with lengths equal to (30, 40, and 50) cm. Three diameters (2.5, 3.5, and 4.1) cm for open ended pipe pile and three flange widths (2.6, 3.6, and 4.4) cm for H-pile are investigated. Jacking technique is employed to installed piles models in dry sandy samples with two different relative densities (60% for medium sand 80% for dense sand). It is found that the pile geometry (diameter and length) with sand density have a high impact on the number of cycles. Analysis of results showed that increasing of pile diameter and relative density cause a reduction in the number of cycles when the length of steel pile models are fixed while variety of diameters of open ended pipe pile has a small effect on the number of cycles. It was found that pipe piles with open ended have more resistance to the cyclic loading compared with H piles under the same geometric conditions (pile diameter, embedded length and sand density) especially in medium sand. Finally, if the testing conditions are the same, number of cycles is decreased with increasing in amplitude loading

KIN SP: A boundary element method based code for single pile kinematic bending in layered soil

In high seismicity areas, it is important to consider kinematic effects to properly design pile foundations. Kinematic effects are due to the interaction between pile and soil deformations induced by seismic waves. One of the effect is the arise of significant strains in weak soils that induce bending moments on piles. These moments can be significant in presence of a high stiffness contrast in a soil deposit. The single pile kinematic interaction problem is generally solved with beam on dynamic Winkler foundation approaches (BDWF) or using continuous models. In this work, a new boundary element method (BEM) based computer code (KIN SP) is presented where the kinematic analysis is preceded by a free-field response analysis. The analysis results of this method, in terms of bending moments at the pile-head and at the interface of a two-layered soil, are influenced by many factors including the soil–pile interface discretization. A parametric study is presented with the aim to suggest the minimum number of boundary elements to guarantee the accuracy of a BEM solution, for typical pile–soil relative stiffness values as a function of the pile diameter, the location of the interface of a two-layered soil and of the stiffness contrast. KIN SP results have been compared with simplified solutions in literature and with those obtained using a quasi-three-dimensional (3D) finite element code.

Application of extended end composite pile design in pile foundation work

Pre-tensioned, spun, high-strength concrete (PHC) piles are the most commonly used type of pile in South Korea. Approximately 60% of the pile's strength is used in the design bearing capacity, and the rest is simply residing in the ground. Increasing the ground bearing capacity is crucial to reduce waste of the pile strength and to improve efficiency. Extended end (Ext) piles are a new kind of composite pile that can overcome the weakness of PHC piles. This study investigates the behaviour of Ext piles. Through field testing, it is confirmed that the bearing capacity of Ext piles is better than PHC piles by about 35% to 50%. Based on the study findings, the Ext pile design reduces the number of piles by around 38% compared to the PHC pile design through application in a selected construction site. The increased bearing capacity of Ext piles affects both work duration and project cost, which are 25% and 14% decreased, respectively.

Analytical Study on RC Framed Structures on effect of Performance of Different types of Piles in Seismic Region

This thesis includes Analytical Study on RC Framed Structures on effect of Performance of Pile Foundation in Seismic Region. For our design section of a RC framed residential high rise building we are comparing mass irregularities and vertical irregularities with respect to Time period, Frequency, Displacement, Storey Drift Ratio and Storey Shear for Friction pile and End Bearing Pile.

FINITE ELEMENT SIMULATION OF PLUGGED OPEN ENDED PILE BEHAVIOR

Open-ended steel pipe piles are widely used for foundations both on land and offshore because of low cost compare with other types of piles and it does not need a high effort for driving. During driving process of these piles into the soil, a soil column known as the soil plug is formed inside the pile. As the penetration continues, the frictional resistance between the inner pile shaft and the soil plug may be developed and in turn may prevent further soil intrusion. Depending on the relative movement between the pile and the soil plug, the pile is considered to be perfectly plugged, imperfectly plugged or unplugged. A numerical modeling of experiments was carried out using PLAXIS-2015 software, in which the Hardening Soil Model (HS small) has been used for soil modeling. During the verification problem used to simulate the experimental results of the pile group G2(2x2), the piles simulated as volume piles and steel cap were modeled using linear elastic model. The simulation showed that the maximum percentage of deviation between experimental and theoretical results is not more than 13.0%. This ratio is considered good when compared to the actual results and the theoretical results with the same values in some of the results.

Frost jacking characteristics of screw piles in seasonally frozen regions based on thermo-mechanical simulations

In this paper, a thermo-mechanical model is proposed to simulate the frost jacking behaviour of screw piles subjected to frost heave, and the results are further validated by laboratory tests. The calculated results show that large multi-helix piles yield the least frost jacking when the freezing depth reaches half the embedment depth of pile. Based on the modified cylindrical shear method and individual bearing method, the optimal geometric parameters of screw piles are determined by a series of numerical calculations. The numerical approach is expected to serve as a reference for designing effective and economical pile types in practice.