3D Pile Research Articles

Low-Contact Impedance Textile Electrode for Real-Time Detection of ECG Signals.

The quality of the electrocardiography (ECG) signals depends on the effectiveness of the electrode-skin connection. However, current electrocardiogram electrodes (ECGE) often face challenges such as high contact impedance and unstable conductive networks, which hinder accurate measurement during movement and long-term wearability. Herein, in this work, a bionic 3D pile textile as an ECGE with high electrical conductivity and flexibility is prepared by a facile, continuous, and high-efficiency electrostatic self-assembly process. Integrating pile textiles with conductive materials creates a full textile electrode for bioelectrical signal detection that can retain both the inherent characteristics of textiles and high conductivity. Moreover, the dense piles on the textile surface make full contact with the skin, mitigating motion artifacts caused by the sliding between the textile and the skin. The continuous conductive network formed by the interconnected piles allows the pile textile ECGE (PT-ECGE) to function effectively under both static and dynamic conditions. Leveraging the unique pile structure, the PT-ECGE achieves superior flexibility, improved conductivity, low contact impedance, and high adaptivity, washability, and durability. The textile electrode, as a promising candidate for wearable devices, offers enormous application possibilities for the unconscious and comfortable detection of physiological signals.

Soil-Pile Interaction of Laterally Loaded Fixed-Head Piles and Pile Groups in Unsaturated Sand

This study investigates the lateral behavior of piles in unsaturated cohesionless sandy soil using centrifuge modelling. The lateral loading was conducted on a single fixed-head pile and 2×2 fixed-head pile groups with 3D and 5D spacings. The results showed that the single fixed-head pile demonstrated greater magnitudes of lateral resistance response compared to the leading and trailing piles of the pile groups. Moreover, the piles experienced greater lateral loads when the water table was about a quarter of the embedded pile depth in the soil layer for the single fixed-head pile and leading piles in the group. The group efficiencies of the pile increased as the water table reduced up to half of the embedded pile length for the 3D pile spacing. However, this effect was negligible for 5D pile spacing. Considering the mixed unsaturated-saturated ground condition can lead to a more resilient foundation design under climate-induced and seasonal fluctuations of water table level and also pave the path for the inclusion of future climatic scenarios.

A Parametric Study: To Find the Optimum Combination of Vertical Piles versus Batter Piles

When the horizontal load per pile exceeds what can be withstood by a vertical pile, battered piles are used in conjunction with vertical piles to improve the overall efficiency of the pile – soil system as they transmit the applied lateral loads partly in axial compression, rather than through shear and bending when only vertical piles are used. A numerical analysis is conducted on a 3D pile raft model with vertical piles and another with inclined piles to check the deformations and other forces for both types of piles

Stacked kinship CNN vs. GBLUP for genomic predictions of additive and complex continuous phenotypes

Deep learning is impacting many fields of data science with often spectacular results. However, its application to whole-genome predictions in plant and animal science or in human biology has been rather limited, with mostly underwhelming results. While most works focus on exploring alternative network architectures, in this study we propose an innovative representation of marker genotype data and tested it against the GBLUP (Genomic BLUP) benchmark with linear and nonlinear phenotypes. From publicly available cattle SNP genotype data, different types of genomic kinship matrices are stacked together in a 3D pile from where 2D grayscale slices are extracted and fed to a deep convolutional neural network (DNN). We simulated nine phenotype scenarios with combinations of additivity, dominance and epistasis, and compared the DNN to GBLUP-A (computed using only the additive kinship matrix) and GBLUP-optim (additive, dominance, and epistasis kinship matrices, as needed). Results varied depending on the accuracy metric employed, with DNN performing better in terms of root mean squared error (1–12% lower than GBLUP-A; 1–9% lower than GBLUP-optim) but worse in terms of Pearson’s correlation (0.505 for DNN compared to 0.672 and 0.669 of GBLUP-A and GBLUP-optim for fully additive case; 0.274 for DNN, 0.279 for GBLUP-A, and 0.477 for GBLUP-optim for fully dominant case). The proposed approach offers a basis to explore further the application of DNN to tabular data in whole-genome predictions.

Finite-Element Analysis of the Lateral Load Response of Monopiles in Layered Sand

Most of the existing design methods for laterally loaded monopiles were developed for uniform soil profiles. The application of such design methods in cases involving layered sand profiles can lead to incorrect capacity estimations. In order to investigate the impact of the soil layering on the response of monopiles to lateral loads and to develop a design method that is applicable to layered soil profiles, a series of three-dimensional (3D) finite-element (FE) analyses were performed on laterally loaded monopiles embedded in layered sand profiles using an advanced two-surface-plasticity constitutive model. The analyses take into consideration a wide range of pile geometries (pile diameter, slenderness ratio, and wall thickness), load eccentricities, sand types and relative densities, and layered soil profiles. The study examines the change of the lateral capacity of a monopile in a two-layer sand profile as the top layer thickness varies, as well as the impact of the presence of a thin loose-sand layer in a dense-sand profile on the pile lateral capacity. Based on the results of these analyses, a set of design equations is proposed to estimate the lateral capacity and load-rotation response of monopiles in layered sand profiles. The proposed method accounts for the 3D pile–soil interaction and provides estimates of the lateral capacity that are in close agreement with those obtained from the 3D FE analyses.

DYNAMIC SOIL-STRUCTURE INTERACTION ANALYSIS: DETECTING THE RELIABILITY OF MODELLING THE PILES AS A PLATE ELEMENT FOR A MULTISTORY BUILDING RESTING ON DEEP FOUNDATION

The assessment of seismic responses of buildings in dynamic-soil-pile-structure interaction problems has been one of the main interests among researchers in recent decades. Simulating such problems is usually done by two-dimensional models to overcome the difficulties encountered in 3D models. Commonly, piles were represented by plate elements of infinite length, disregarding the soil flowing between piles. Recently, Plaxis – a finite element software- implemented a new feature known as “the embedded pile row” that allows the definition of piles' out of plane spacing in a 2D model. Many researchers proved its validity in accurately simulating the real 3D pile’s behavior. The objective of this paper is to detect the reliability of modeling the piles as plate elements, by comparing the performance of the structural-pile system with the plate feature to that with the embedded pile row feature. A series of 2D finite element models are generated while varying the soil type, the earthquake frequency content, and the out-of-plane piles' spacing. This paper demonstrated that the building response with piles modeled as plate elements is just adequate when the surrounding soil is dense. Yet, regarding the pile response, the plate feature is unable to capture the real behavior for all soil types.

Three-Dimensional Analysis of Nonlinear Pile–Soil Interaction Responses Using 3D Pile Element Model

Abstract Due to the complicated geological conditions and complex loads, the pile–soil interaction is a three-dimensional (3D) and highly nonlinear problem. Conventional numerical models have defic...

Numerical analysis of the performance of pile cap on a single pile for a lateral bearing capacity in layered soil

Deep underground infrastructure is booming technology in developing countries, and these construction techniques are mostly used in developed countries at present. Pile foundation among many types of deep structures, it is significantly researched and built to sustain and transfer loads from superstructures to deep soil, in either case, the load from the superstructure is very high or the soil at shallow depth is too weak. Piles are subjected to axial, horizontal, momentary, and combined loading systems as a single pile or pile group system connected to the reinforced pile cap on top of the pile to share or transfer loads through the wall and tip to the surrounding soil. Along with elastic solid pile-pile cap characteristics of materials, a limited number of numerical and analytical studies are published even merely on a homogeneous soil placement of the pile cap model. However, The soil’s natural deposit at a significant site may not always be found homogeneous on which pile-caps and piles are placed. To fill the gap of an intricated multi-physics soil-structure interaction problems, successive analysis is incurred to be proliferated. The study presented a numerical analysis of the influence of the pile cap on the single laterally loaded pile, while the embedding of the pile cap varied on the layered soil profile. The standard linear static numerical analysis software ABAQUS was used to model 3D pile cap-pile and layered soil with subjected lateral load and relevant boundary conditions. The result of the analysis was plotted varying the embedding of the pile cap on clay overlaid sand and sand overlaid clay interchangeably taking into consideration other influencing parameters (pile capsize and vertical load). The increase in pile cap embedment on clay overlaid sand slightly increases the lateral resistance of the pile cap for the first few increments and small non-linear variation for further embedding from the analysis has resulted. However, the performance of the pile cap for lateral load resistance was significantly increased as the depth of embedding of the pile cap is increased on sand overlaid clay. Besides, the size of the pile cap has a direct proportion for lateral resistance, and the vertical load exerted on a pile cap has not had a significant influence. The study comprehensively emphasized the interaction of piles with simple soil physics problems, but multi-soil physics problems with pile interaction should be analyzed for future study.

Comparative effects of adjacent loaded pile row on existing tunnel by 2D and 3D simulation models

Selecting suitable simulation methods for complex problems requires a careful balance between the predicted accuracy and computational effort. This research comparatively investigated the effects of adjacent loaded pile row on an existing tunnel in terms of tunnel deformation and lining force, displacement of soil surrounding between tunnel and pile and load transfer of the pile. Simulations were carried out by eight simulation models consisting of 3D finite element (FE) full models (model 1-2); 3D FE symmetry models (model 3-4); and a pile wall in 2D FE models (models 5-8). In loaded pile row simulation, simulations were performed with two pile types: volume pile and embedded pile. In 2D simulation, the 3D pile row was converted into 2D pile wall under plane strain condition by using three transformation methods. The results show that the predicted tunnel responses are adequately accurate as long as the reasonable soil movement behavior can be reproduced. The 2D equivalent dimensions and 2D equivalent axial rigidity are recommended since they provide conservative estimation on both tunnel deformation and lining forces. The 2D equivalent flexural rigidity is not recommended if the pile response is also of concern. The novelty of this research lies in the use and discussion on the applicability of various 2D and 3D models to simulate the effects of adjacent loaded pile row on the existing tunnel, as opposed to previous studies which focused on one or two simulation models.

INTEGRATION OF INFORMATION AND COMMUNICATION TECHNOLOGY (ICT) INTO CEMENT DEEP MIXING METHOD

In the deep mixing improvement method, soil-cement columns are installed in to an invisible ground, therefore it is impossible to visually confirm the circumstance of the constructions process. As the results, the inadequacy of construction data management and quality control of the constructed soil-cement columns may happen following re-construction of the columns, and structures failures/damages in some cases. By incorporating the Information and Communication Technology (ICT), authors have invented and developed a system to visualize the construction process of the deep mixing work in real-time, namely “3D Pile Viewer”. This system consists of two functions that are the positioning guidance and the visualization of the construction information. The former has been developed by using the combination of the Global Navigation Satellite System (GNSS) or the Total Station (TS), and the tilt sensor. The latter is to create three-dimensional model of all information during construction such as depth, electrical current value, amount of slurry, rotation speeds, etc., then sharing via internet. By introducing the newly developed system to various actual construction sites Japan and oversea, the practical performance of the system and its advantages have been confirmed.

Simulation analysis of low strain dynamic testing of pile with inhomogeneous elastic modulus

Low strain dynamic testing is an important nondestructive testing method in the engineering. However, the pile foundation material is usually assumed as having a uniform elastic modulus in low strain simulations. In this paper, we consider the elastic modulus of concrete as having an inhomogeneous elastic modulus that is described by the Weibull distribution model. An explicit algorithm was adopted in order to solve the model. The finite element method (FEM) was used to simulate the low strain dynamic test of a 3D pile. The response velocity characteristics of different shape parameters were obtained using this method, and the Daubechies wavelet transform was used to analyze the characteristics of the wavelet modulus. The result shows that simulation response velocity has a correlation with the different homogeneity of the elastic modulus.

Discrete element modelling study of force distribution in a 3D pile of spherical particles

We present a numerical analysis of the transmission of contact forces in a granular pile comprising 50,000 frictional, coarse spherical particles. The goal of our study is to understand the microscopic origins of macroscopic behaviours, such as the pressure dip at the centre of the base of a conical pile. The particles are 8.2mm in diameter with a standard deviation of 0.1mm to avoid ordering effects. The effects of the pouring method, inter-particle sliding friction and rolling friction on the distribution of static stress are examined. The analysed microscopic variables are the distributions of the values and directions of the contact forces as well as the degree of mobilisation of contact friction. The vertical, radial and shear stress components are derived from the discrete contact forces. The analysed macroscopic variables are the distribution of the stress components, mobilisation of internal friction and inclination of the major principal stress to the vertical. The simulation results show that certain combinations of the examined factors lead to the formation of dome-shaped structures of maximum values of mean pressure as determined by the stress distribution inside the pile as well as at its base.

Centrifuge Modeling of Laterally Loaded Pile Groups in Improved Soft Clay

AbstractA series of centrifuge tests were performed to investigate the behavior of laterally loaded pile groups in improved and unimproved soft clay. The soil profile consisted of four lightly overconsolidated clay layers overlying a dense layer of sand. The pile groups had a symmetrical layout consisting of 2×2 piles spaced at 3.0 and 7.0 pile diameters (D). After improving the soft clay in situ using simulated cement deep soil mixing (CDSM), pile foundations were driven into the improved ground. Centrifuge tests revealed that CDSM is an effective method to increase the lateral resistance of pile foundations. The lateral resistance of the improved pile group at 7D spacing increased by 157%. Due to pile–soil–pile interactions, the lateral resistance in the 3D pile group increased by only 112%. In both improved and unimproved pile groups with 3D spacing, the leading row of piles carried larger loads and bending moments than the trailing row of piles. No group interaction effects were observed in all pile g...

Three-Dimensional Stability Analysis of a Homogeneous Slope Reinforced with Micropiles

Micropiles are widely used to reinforce slopes due to their successful performance and fast construction. In this study, a simple nonlinear method is proposed to analyze the stability of a homogeneous slope reinforced with micropiles. This method is based on shear strength reduction technique, in which the soil behavior is described using the nonassociated Mohr-Coulomb criterion and micropiles are modeled as 3D pile elements. A series of slope stability analyses is performed to investigate the coupled mechanism of micropile system, and the optimum of pile position, depth of embedment, and length of truncation are analyzed. Results show that the position of micropile system plays an important role not only in the calculation of the safety factor, but also in locating the failure surface, which demonstrates the dominating coupled effect exists between micropiles and slope. The critical embedment depth of the micropile is about 2 times the length of micropile above the critical slip surface, and the micropiles flexure rather than rotation becomes increasingly prevalent as the depth of micropiles embedment increases. Truncation of micropiles may improve the capacity of the micropile system, and the largest truncation length of micropile is about 1/4 depth of critical slip surface in this study.

Lateral stiffness of hybrid foundations: field investigations and 3D FEM analysis

The paper presents stability problems of horizontally loaded pile–soil interaction in the three-dimensional (3D) state of strain. The results obtained are based on full-scale tests and numerical 3D finite-element method analyses including an evaluation of the interaction between the soil and a pile with a cantilever plate. The research and analyses carried out resulted in a better specification of the current methods calculation for a single pile with cap. An analysis of the 3D pile–soil interaction enabled development of the basis for a more precise determination of the lateral stiffness of a pile with cap in cohesionless soil. A better understanding of the problem is of vital importance for designing bridge abutments, retaining walls founded on single rows of piles, foundations supporting structures, and offshore wind turbines subjected to large lateral loads.

Analysis of static axial load capacity of single piles and large diameter shafts using nonlinear load transfer curves

A modified analytical model is proposed in this study for the analysis of pile axial load capacity with the load transfer method using nonlinear T-z and Q-z curves to model soil-pile behavior in skin friction or side shear and end bearing respectively. The method uses a three-dimensional (3D) pile model using solid finite elements with nonlinear load transfer curves resolved into components and mobilized around the pile perimeter. The use of multiple T-z component springs is demonstrated to accurately capture the total side resistance of the pile. The 3D pile method produces results of predicted pile axial load capacities from the load-settlement curves comparable to the one-dimensional analysis (1D) method. For a combined vertical and lateral loading on the pile, the proposed 3D pile method can address the limitation of the 1D pile method having vertical and lateral springs only acting at the pile center without rotational springs, which neglects the contribution of the side shear in the computation of pile bending moments. In the case of 3D pile model the moment or couple developed by the side shear around the perimeter can be taken into account, where this moment can be significant especially in strong soil material or in the case of large diameter pile/shafts.