Pile Installation Research Articles

Method of Location and Capacity Determination of Intelligent Charging Pile Based on Recurrent Neural Network

With the popularity of new energy vehicles, a large number of cities began to focus on the installation of electric vehicle charging piles. However, the existing intelligent charging piles have faced problems such as short supply, unreasonable distribution areas, and insufficient power supply. In response to these problems, this research proposes a recurrent neural network algorithm with an integrated firefly algorithm. Based on these two algorithms, a charging pile location and capacity model was established, and users’ travel habits were analyzed according to the model. In the simulation experiment, the PR curve analysis of the algorithm was carried out first. The analysis results showed that the AP value of the recurrent neural network algorithm combined with the firefly algorithm was increased from 0.9324 to 0.9972. In addition, it had higher accuracy and stability than before, which also verified the feasibility of the algorithm. Finally, through the model, the user’s travel habits were analyzed in detail. From the perspective of total demand, the charging demand of commercial centers was the highest, with a peak of about 537 kw, followed by 501 kw in office areas and then about 379 kw in parks. The kw charging demand in other areas was below 200 kw. The above results show that the recursive neural network can effectively determine the location and capacity of the charging pile, which is of great value to the development of transportation and new energy.

A simple approach for marine mammal noise-induced threshold shift prediction from down-the-hole piling noise exposure

In assessing auditory effects on marine mammals from noise exposure, a dual-criterion is currently used by regulators to estimate the noise-induced threshold shift (NITS). Such criterion classifies anthropogenic noise into two mutually exclusive categories: Impulsive and non-impulsive. However, in real world situations, marine mammals are often exposed to complex noise field that contains both impulsive and non-impulsive components, thus makes it difficult or even impossible to accurately assess their NITS from noise exposure. One example is down-the-hole (DTH) pile installation, which generates both impulsive noise from percussive drilling/striking and non-impulsive noise from debris removal simultaneously. In this study, a relatively simple approach is proposed that employs kurtosis values to quantify the impulsiveness of two DTH piling noises datasets for six different marine mammal functional hearing groups. A kurtosis adjustment approach that has been suggested for predict human hearing loss from noise exposure was then used to build correction factors for estimation of NITS of marine mammals exposed to DTH piling noises. Further research on marine mammal NITS from complex noise exposure is needed to validate and improve this model.

Axial Behavior of Pressure Grouted Helical Piles Installed in Marine Soft Clay Based on Full-Scale Field Tests

Axial Behavior of Pressure Grouted Helical Piles Installed in Marine Soft Clay Based on Full-Scale Field Tests

Eco-Economic Performance Estimation Method for Pretensioned Spun High-Strength Concrete Pile Installation

Pile installation has an environmental impact through its various processes ranging from raw material extraction to construction. In addition, the environmental performance, productivity, and cost of pile installation depend on the construction plan. Therefore, the chain of activities must be considered when analyzing the sustainability of pile installation. A rational construction plan must carefully examine the factors that affect the productivity and sustainability of pile installations. This study presents a method for evaluating eco-economic performance by analyzing the resource utilization and processes of PHC pile installation. First, a process modeling technique, wherein details are broken down to the work task level, based on energy consumption and resource cost, is proposed. Second, a simulation method that calculates the eco-economic performance of the PHC pile process and resources (e.g., equipment) is presented. Third, a quantitative comparison of durations, costs, and emissions resulting from simulation, estimation based on the CSPR (Construction Standard Production Rate) and IUC (Itemized Unit Cost), site contract, and actual construction is presented. The results reveal that the method effectively reflects the prediction of duration, cost, and carbon emissions generated in the real world during the construction planning stage.

Energy flux analysis for quantification of vibratory pile driving efficiency

In this paper, the energy flux in a pile modeled as an elastic shell, is studied theoretically and experimentally. Based on this analysis, a new procedure is proposed to quantify the pile installation efficiency. This procedure is of importance for vibratory installation of the foundations of offshore wind turbines and it is believed to be the first procedure that relies directly on the energy propagating down the pile rather than the energy supplied by the vibratory shaker. The proposed approach is tested on piles installed by two distinct vibratory techniques, i.e. the axial vibratory driving and the recently developed Gentle Driving of Pile (GDP) method. The field data obtained during an experimental campaign were analyzed with the proposed energy flux approach. The cumulative energy flux in the pile normalized by the energy input of the shaker is found to be the best measure for quantification of the installation efficiency. Correspondingly, the main proposition of this paper is that the installation efficiency will be maximized provided that the normalized cumulative energy flux is at its maximum.

Effects of full displacement pile installation on the stress and deformation state of surrounding soil: review

Effects of full displacement pile installation on the stress and deformation state of surrounding soil: review

Stress-strain state modeling of brick building on pile foundation to provide spatial rigidity

The aim of this work is the instrument-aided structural survey to recover the operability of a five-storey brick building on a pile foundation after significant deformation. Methodology: The MicroFe software is used to simulate the stress-strain state of the building and develop the base–foundation–building system model. Research findings: During both construction and operation of the building, its spatial stiffness is disturbed with the crack formation in brick walls due to insufficient pile installation, i.e., the pebble-gravel layer is not reached owing to difficult engineering and geological conditions. Practical implications: The obtained results are used to develop recommendations to ensure the required spatial stiffness of the building by the outer wall reinforcement with strained steel bars locating at the level of intermediate floors.

Numerical Analysis of the Installation Process of Screw Piles Based on the FEM-SPH Coupling Method

The installation of screw piles can cause damage to the soil, which is a dynamic and large deformation problem. In this paper, a FEM-SPH numerical model for the analysis of this large deformation problem was developed in LS-DYNA to simulate the installation process of screw piles. In addition, field installation tests of screw piles were carried out. By comparing the FEM-SPH simulation results with the experimental results and traditional FEM simulation results, it was found that the FEM-SPH coupling method has higher efficiency and accuracy in dealing with the large deformation problems caused by the installation of screw piles. Then, numerical simulations of screw piles with various parameters were conducted to analyze the differences in the installation process. The results show that the spiral pitch and pile diameter have a significant effect on the installation torque, soil stress and soil pressure during the installation process. During the installation process, the interaction between the screw pile and the soil is transferable. The installation of the screw pile will lead to the movement of soil particles in the radial and axial directions, resulting in heave damage to the shallow soil and cylindrical shear damage to the middle and deep soil. The influence range on the soil by the heave failure mechanism (HFM) and the cylindrical shear failure mechanism (CSFM) caused by the installation of screw piles is affected by pile parameters. The change in pile diameter will act on both HFM and CSFM, whereas the variation in spiral pitch will only have an influence on CSFM.

Correlative neutron and X-ray tomography imaging of pile installation in chalk

Neutron and X-ray computed tomography (NCT and XCT, respectively) are imaging techniques that are increasingly applied in geomechanics research. They are used to non-destructively reveal different microstructural aspects of geomaterials: XCT is often used to observe/quantify differences in density or porosity, while NCT reveals the presence and distribution of hydrogenous materials such as water. The correlated use of NCT and XCT for geomechanics and geotechnics research is in its infancy. To this date, very few experiments have been carried out that combine both techniques, and none has been used to investigate geomaterial–structure interaction. This paper presents the first correlative NCT–XCT imaging study of pile installation. A scaled model pile was installed in an unsaturated intact chalk cylinder and in situ NCT and ex-situ XCT synchrotron-based imaging was applied consecutively. Chalk was used because the behaviour of displacement piles installed in this material is still subject to considerable uncertainty. Results reveal for the first time the interaction between installation-induced changes in chalk density and water distribution variations, with evidence of water displacement into the densified material in the vicinity of the installed pile. A straightforward method for correlative bulk density–moisture content determination from NCT–XCT images of geomaterials is presented and their limitations are discussed.

MPM modeling of pile installation in sand: Contact improvement and quantitative analysis

The material point method (MPM), which is known to be advantageous in modeling large deformation and contact problems, is utilized in this study to simulate displacement pile installation in sand. A modified Bardenhagen’s contact algorithm is proposed that calculates the node-to-surface distances between the deformable soil mass and the rigid pile surface more effectively, along with a smoothing factor for the change of momenta between the contacting bodies. The modified algorithm is shown to produce more accurate and stable contact results. Three tests, namely, the rolling cylinder, the penetrating wedge, and the strip footing, are first conducted to demonstrate the validity of the modified algorithm. It is then applied to analyze the installation of a closed-ended pile, employing a state-dependent Mohr–Coulomb model to capture the sand’s state-dependent shearing behavior. Detailed analyses of the stress and deformation fields developed around the pile during steady penetration reveal quantitative agreement between the MPM predictions and published experiments, indicating that the approach holds promise for use in more sophisticated analyses designed to improve the understanding of industrially driven piles.

Research on Lateral Bearing Behavior of Spliced Helical Piles with the SPH Method

The length of a spliced pile is 2 m assembled from an original spiral pile using a connector. The whole pile is the structure of the upper straight pipe and the lower spiral. The pile–soil model is established with FEM-SPH by LS-DYNA to simulate and analyze the characteristics of the spliced piles. When the helical pile is subjected to a horizontal load, the pile rotates around the point of rotation, and the contact force position of the soil in the model is as expected. During the process of pile driving, the soil forms an inverted cone stress-area, and the maximum particle stress area near the pile tip and the ground surface is 400 Kpa, which is highly concentrated. When loaded laterally, the area of the interaction stress of the soil particles is divided into three regions: the stress effect region; the transition region; and the critical region. Then, 7° is defined as the ultimate horizontal bearing-capacity of the spliced pile, and the numerical simulation of the horizontal bearing-capacity fundamentally matches the test results. The simulation model realizes the transition from the pile installation to the lateral loading, predicts the ultimate horizontal bearing-capacity, and analyzes the stress distribution of the soil particles and the time-development of the soil displacement.

Contribution for a root pile installation control approach using a digital odometer

A root pile is a form of injection pile (cast-in-place with pressure, with very distinct construction aspects from the known micropile type). During the mortar shaft development, these piles are inserted using distinct injection pressures of up to 500 kPa. Static load tests are typically used to control root piles, which can be an expensive and time-consuming testing procedure. Static load tests were performed on eight monitored piles with diameters of 350 and 410 mm to investigate root pile performance control during pile installation. This research presents a refined and developed alternative methodology for confirming root pile performance using a digital odometer attached to the drill rig’s rotatory head. The methodology consists of monitoring variables obtained during pile installation related to pile bearing capacity. Moreover, empirical equations with simple and relevant applications to estimate root pile bearing capacity during installation are proposed. The developed equations produced results consistent with the values obtained from static load testing on the test piles. Therefore, the results suggest that the proposed methodology is a viable alternative for root pile performance control.

Influence of Perforated Soils on Installation of New Piles

In recent years, there has been an increasing demand to replace ancient structures. The removal of such structures also involves the removal of the existing piles that supported the structures, and the backfilling of the pulling-out holes that formed during the removal. However, there are no standard guidelines for the backfilling of pulling-out holes. At present, therefore, each owner or contractor must determine the material and the construction method to use for backfilling. This results in a difference between the mechanical properties of the original soil and those of the soil that has been backfilled, namely, the soil on which a newly built structure will be constructed. In this study, it was assumed that a new pile would be installed on a perforated soil (that is, the soil left after removing the existing piles) where the mechanical properties differ between the original soil and the backfilled soil. The behavior of the new pile, when installed on the boundary of a soil between two types of mechanical properties, was evaluated by a three-dimensional linear elastic analysis. When the new pile was installed at the boundary between the two types of soil with different mechanical properties, most of the new pile was inclined to the soil side where the N value was relatively small. However, the inclination of the new pile was able to be suppressed by increasing the distance from the boundary between the two types of soil.

EFFECT OF CLAY SHALE SHEAR STRENGTH DEGRADATION ON BORED PILE FRICTION IN CLAY SHALE

This research aims at investigating and modeling the axial bearing capacity degradation of a bored pile on clay shale due to the bored pile installation processes. Clay shale sample models were prepared to simulate the wetting and drying cycles through weathering process between 0 to 6 hours. All samples were tested in which every 1 hour of the weathering process representing 1 cycle of wetting and drying. The direct shear laboratory tests were performed to obtain the peak and residual shear strength parameters of the interface between the bored pile and clay shale. The peak and residual shear strength parameters were obtained after 6 hours of the weathering process. The residual shear strength parameters were measured by applying with and without stress release. This investigation showed that the shear strength degradation at peak, residual without stress release, and residual with stress release respectively reached 87-62%, 28-20%, and 25-14% after 1 to 6 hours of weathering process. This result is very useful for predicting the bored pile skin friction in clay shale soils.

Numerical assessment of tip damage during pile installation in boulder-rich soils

The number of incidents worldwide where pile tip damage has occurred during driving has accelerated following the growth of the offshore wind sector, and the expansion into areas with increased risk of embedded boulders or partially weathered soft rocks. The process involving pile–boulder–soil contact can be simulated with advanced three-dimensional (3D) large-deformation dynamic coupled Eulerian–Lagrangian (CEL) finite-element (FE) analysis. However, analyses of this nature are highly time-consuming and computationally expensive. The objective of the paper is to develop a generic framework whereby the potential for denting by a boulder can be assessed a priori. The study encompasses four main components to determine the magnitude of force necessary to create plastic damage of the pile tip and what combination of boulders and soil might generate such reactions during pile installation: (a) a parametric 3D FE structural denting study; (b) a parametric boulder–soil 3D CEL study, where prescribed displacements were applied to the surface of boulders embedded in sand; (c) a range of pile–boulder–soil 3D CEL analyses where a deformable pile and different boulder–soil combinations were simulated; and (d) centrifuge model tests involving tip damage from boulders. Simple relationships and charts have been established from the numerical studies and validated from experimental work.

Model tests on jacking installation and lateral loading performance of jacket foundation in sand

The long-term dynamic behavior of pile under cyclic loads is important for the stability and safety characteristics of jacket supported offshore wind turbine. In this study, large-scale indoor model tests were carried out on the jacking installation and lateral loading of jacket foundation in sand. For the process of pile installation, it shows that the linear growth of pile tip resistance during installation can be divided into two stages, and its critical depth (the depth at which the growth rate of pile tip resistance begins to decrease significantly) is 11D (diameter). The jacking resistance of latter pile is significantly greater than that of former pile. Under static load, the maximum bending moment point of front row pile is higher than that of back row pile. The depth of bending moment reverse point is also 11D for front and back row piles. Under cyclic loads, the displacement at tower top undergoes two stages: rapid growth stage and slow growth stage. The friction resistance of back row pile increases first and then decreases along depth, showing an oblique “V” shape. The natural frequency varies with different load frequencies and cyclic load ratios. The evolution trend of system damping ratio and natural frequency is roughly opposite.

Kurtosis analysis of sounds from down-the-hole pile installation and the implications for marine mammal auditory impairment.

Sounds from down-the-hole pile installation contain both impulsive and non-impulsive components. Kurtosis values (β) were determined for two datasets to investigate the impulsiveness of piling sounds. When the hammer struck the pile(s), β was 21-30 at 10 m and approximately 10 at 200 m. When the hammer was used for drilling without contacting the pile, β was 4-6 at all distances. These findings suggest that a simple dichotomy of classifying sounds as impulsive or non-impulsive may be overly simplistic for assessing marine mammal auditory impacts and studies investigating the impacts from complex sound fields are needed.

Pile Installation Assessment of Offshore Wind Jacket Foundation in Completely Weathered Rock: A Case Study of the South China Sea

The assessment of pile drivability is the premise of successful pile installation, and completely weathered (CW) rock may bring the risk of pile refusal. This paper presents a case of pile driving refusal that occurred in a CW gneiss layer. The physical and mechanical properties of the CW gneiss are analyzed based on the results of a laboratory test, a cone penetration test (CPT), and a standard penetration test (SPT). By comparing the properties of CW gneiss with those from intact gneiss, the CW gneiss layer in this study was found to be soil-like. Additionally, it is a sand-like layer according to CPT-based soil classification systems. The soil resistance to driving (SRD) in pile driving was calculated with different methods for sand and compared with the SRD inferred from the pile-driving records. The results show that the modified Fugro’s method assuming a fully plugged condition may provide good pile drivability assessment in this study. It was found that it is necessary to determine the properties of the CW rock layer reasonably before conducting pile driving analysis, and a framework is proposed for analyzing the pile drivability in a CW rock layer based on this case study.

Regional-scale investigation of pile bearing capacity for Canadian permafrost regions in a warmer climate

Climate change is being experienced particularly intensely in the Arctic and therefore adaptation of engineering systems for this region cannot be further delayed. However, one of the major barriers to studies focused on adapting northern engineering systems is the lack of information at the spatial and temporal scales required for engineering applications. This study investigates pile bearing capacity for selected pile configurations for the Canadian permafrost regions (Nunavut and Northwest Territories), for current and future climates, using the very first ultra-high resolution (4 km) climate change simulation developed for the region using the Global Environmental Multiscale (GEM) model, for a high emission scenario.Comparison of the ultra-high-resolution GEM simulation, driven by reanalysis, with available observations confirms the model's ability in representing near-surface permafrost and related climate variables. The estimated adfreeze contribution to the total bearing capacity, for current climate, informed by the reanalysis-driven GEM simulation, for a 5-m cement pile, is found to be of the order of 15% for regions with shallow bedrock and 80% for regions with deeper bedrock. Application of the GEM climate change simulation outputs, for RCP8.5 scenario, suggest decreases to adfreeze contribution in the 5–30% range by 2040, with the largest differences noted for regions with deeper bedrock. For steel piles of same configuration, although the adfreeze contributions are only about 70% of that for cement piles, the projected relative changes are of similar magnitude.Further downscaling to 250 m resolution using the land model of GEM for the Slave Geological-Grays Bay corridor, where future developments are planned, including an all-season road, enables better estimation of bearing capacity for realistic pile scenarios such as those for bridges (in thick layer of sediments) used for river crossings. Due to the wide variation of pile materials, lengths and installation methods, site specific information can be developed from the framework developed in this study. The results of this study, including the ultra-high resolution climate change information, will thus form the basis for additional detailed investigations on climate-infrastructure interactions and climate resiliency studies.

Analytical method for predicting pile running during driving

Most offshore structures, such as conventional oil and gas jacket platforms or wind turbines, are typically supported by driven large-diameter steel piles. The piles resist the loads of the superstructure and environmental wind and wave forces. Pile running is a major hazard associated with the installation of driven piles in a layered seabed. An analytical method based on Newton's second law of motion is proposed to predict pile running. Two methods are used to calculate the soil resistance to dynamic penetration: (1) the conventional American Petroleum Institute (API) method, where the strain rate dependency and remoulding of the surrounding soil are considered, and (2) the Cone Penetration Test (CPT)-based method, which accounts for friction fatigue. The drag resistance in the context of fluid mechanics has also been considered for pile running. The velocity at the start of pile running was determined by the energy delivered by the piling hammer. A numerical programme was implemented and validated, and then used for three case studies; the results obtained were in good agreement with field measurements. The method presented in this study is dependable for analysing pile running and can provide significant support for pile installation assessment and risk management in offshore engineering design.