Shape Of Pile Research Articles

World Modeling for Autonomous Wheel Loaders

This paper presents a method for learning world models for wheel loaders performing automatic loading actions on a pile of soil. Data-driven models were learned to output the resulting pile state, loaded mass, time, and work for a single loading cycle given inputs that include a heightmap of the initial pile shape and action parameters for an automatic bucket-filling controller. Long-horizon planning of sequential loading in a dynamically changing environment is thus enabled as repeated model inference. The models, consisting of deep neural networks, were trained on data from a 3D multibody dynamics simulation of over 10,000 random loading actions in gravel piles of different shapes. The accuracy and inference time for predicting the loading performance and the resulting pile state were, on average, 95% in 1.2 ms and 97% in 4.5 ms, respectively. Long-horizon predictions were found feasible over 40 sequential loading actions.

AN ASSESSMENT OF STEMMING TECHNIQUES AND THE PERFORMANCE OF STEMMING PLUGS IN BENCH BLASTING OPERATIONS IN PAKISTAN

This research article presents a comparative analysis of stemming techniques and the performance of stemming plugs in bench blasting operations, based on a case study carried out in cement quarries of Pakistan. For Image analysis, the Wip-Frag software is utilized in order to demonstrates the benefits of stemming plugs over traditional methods. Real time images captured during blasting at various cement quarries reveal a substantial presence of boulders within the muck pile when using conventional stemming materials such as drill cuttings and clay. This typically requires additional time and costs for secondary drilling and blasting or hydraulic hammering. Blast tests results indicate that stemming plugs improved the throw and shape of the muck pile, and significantly decreased the boulders percentage. This study also compares the results of Wip-Frag software with sieve analysis of drill cuttings, indicating potential limitations in the software's reliability for particle size distribution. These results contribute to improve blasting operations and emphasize the importance of proper stemming techniques. improving blasting efficiency, the use of stemming plugs can potentially minimize the operational costs and improve overall performance.

Lateral pressure on pile foundations in cohesive soils due to horizontal soil movements

In soft soil layers, piles are frequently loaded laterally by horizontal soil movements. In many cases, the lateral pressure acting on piles due to horizontal soil movements is calculated with empirically or analytically based approaches, respectively. However, most of these design approaches do not consider possible influences on the resulting pile loads. This paper presents the results of model tests and numerical simulations on single piles and pile groups in cohesive soil subjected to lateral loads which were carried out to overcome limitations of available design approaches. Based on extensive small-scale 1 × g-model tests and numerical investigations with the finite element method, influencing factors on the lateral pressure, such as the roughness of the pile–soil interface, the pile size, the pile shape and the pile spacing were identified. A parametric study with the numerical model quantified the most relevant factors influencing the development of lateral pressure on piles due to adjacent surface loads and lead to the development of a simplified analysis approach.

Experiment investigation on the local scour around circular and square piles in open wharf

Open wharves often rely on pile structures for stability, but these can cause local scouring, risking structural integrity and safety. Understanding scour mechanisms induced by propeller jet flow is crucial for effective scour protection, yet research on square piles and double piles is limited. This study presents a series of flume tests to investigate the local scour mechanisms around square piles and circular piles under propeller jet flow. The experiments consist of seven different configurations, including single square piles, double square piles, single circular piles, double circular piles, and a control case without any piles. The main focus of this research is to understand the development and variations of scour depth and scour pit dimensions induced by propeller jet flow. Additionally, the scour mechanisms of square piles are compared with those of circular piles, and the influence of double piles and pile spacing is examined. It can be found that substituting circular piles with square piles in practical engineering will generally lead to an increase in the overall scouring range of the foundation. The horizontal scouring range of double piles is significantly influenced by the pile spacing, resulting in a larger range with increased spacing. However, the variation in pile spacing has minimal impact on the vertical scouring range of the double piles. The shape of piles significantly impacts scour depth in both single and double-pile setups, with square piles resulting in deeper scour. Furthermore, increased pile numbers and narrower spacing contribute to higher scour depths. The results of this study enhance understanding of scour characteristics and offer valuable insights for designing and maintaining pile-supported open wharves, ensuring the safety and durability of waterfront structures through effective scour protection measures.

Spontaneous ignition of rubber woodchip in Thailand

The self-ignition temperature, the safe pile storage dimension and the activation energy of the rubber woodchip pile were determined by Frank-Kamenetskii approach. The woodchip samples with 278 kg/m3 and 458 kg/m3 of the bulk densities and 10.6% w.b. (wet basis) and 46.1% w.b. of the initial moisture contents were used. The samples were put into the cubic baskets with the widths of 8 cm, 10 cm, and 12 cm and placed in the well-ventilated oven. The results showed that the self-ignition temperatures were varied between 182 °C and 199 °C. The increase in the basket sizes decreased the self-ignition temperatures. The initial moisture content did not affect the self-ignition temperature. The dimension and shape of the rubber woodchip piles affect the self-ignition temperature. The size of the safe storage pile could be larger if the moisture content increased. The activation energy of the rubber woodchip ignition increased when the moisture content increased. The activation energies were 97.9 kJ/mol and 104.2 kJ/mol, for the moisture contents of 10.6% w.b. and 46.1% w.b., respectively.

Experimental investigation of model piles subject to lateral load in cohesionless soil

In this research work, the way piles behave in sandy soil and are exposed to lateral forces was examined experimentally by using several lab examinations. These tests were performed on a model of steel piles, including a closed-ended circular pile, a closed-ended square pile, and an H pile. The outcomes of the experimental tests were presented as load-displacement diagrams to examine how pile length and shape affected lateral load capability. Moreover, along the length of the pile, the bending moments were obtained and presented as relationships between the bending moment and the pile length. Therefore, it can be said that piles' capacity to support lateral loads rises with increasing pile length for each of the study's pile shapes. Additionally, it finds that the H-pile has a greater lateral load capacity and maximum bending moment than other piles.

Experimental Evaluations of Model Piles Subject to Inclined Loading in Sand

The structures that subjected to varying loads are supported by pile foundations. These loads consist of inclined and vertical loads. The main objective of this work is to experimentally investigate the effects of an inclined load on the lateral pile reaction and axial pile displacement for piles found in cohesionless soil. For this purpose, the slenderness ratios of model steel piles are varied by values of 11, 14, and 17. Moreover, the pile shapes involved in this study are H-pile, closed end circular and square. The experimental tests were conducted in sandy soil. However, the load inclination angle included in assessing the pile behavior were 0, 30, 45, and 60 from the vertical. In order to study the above parameters on the behavior of model pile, thirty-six experimental tests were carried out. Several findings indicated that the lateral pile deflection was highly influenced by increasing the load inclination. Further, the load inclination effect on the pile's ultimate bearing capacity is high which leads to a reduction in the pile's capacity. Additionally, the vertical displacement of pile is less than horizontal displacement when the pile is subjected to an inclined load of 45° and the model fails by horizontal displacement.

The Calculation Method for the Horizontal Bearing Capacity of Squeezed Branch Piles Considering the Plate–Soil Nonlinear Interaction

The m-method is a commonly used method to calculate the internal force and deformation of pile foundations under lateral loads. However, for squeezed branch piles, the increase in the load-bearing plate leads to changes in the pile section and the generation of a resistance bending moment under loading, which means the load–displacement relationship at the load-bearing plate will no longer satisfy the linear relationship. In this paper, a hyperbolic load transfer model is established to describe the nonlinear relationship between the soil resistance and lateral displacement at the branch of the pile, and the m-method is used for the straight section of the pile. Laboratory model tests are used to verify the correlation between theory and experimentation. The results show that the theory is consistent with the measured curve. On the basis of the theoretical calculation, the influence of the bearing plate and pile body parameters on the force of the squeezed branch pile is analyzed. The research shows that that the bearing capacity of the squeezed branch pile is improved by increasing the plate’s diameter, placing the plate closer to the ground, and ensuring that the pile top is embedded. The theoretical calculation method established in this paper can correctly and accurately reflect the bearing capacity characteristics of squeezed branch piles under horizontal loads, and it is more safe than performing measurements. Additionally, it can be applied to squeezed branch piles with different plate diameters, plate positions, plate section forms, and plate quantities as well as for piles with different boundary conditions and soil conditions. Moreover, it can also be applied to other pile shapes. This method is of significance for the analysis of the bearing characteristics of piles with variable sections under lateral loads.

Axial and Lateral Load Test Performance of Steel Fin Pile

Steel fin piles may offer increased resistance to lateral and torsional loading; however, there is limited experimental data in the literature for steel fin pile performance. This study evaluates the performance of steel fin piles through field load testing and numerical analysis. Axial and lateral load tests were conducted on two fin piles with a diameter of 273 mm and a length of 3.73 m to evaluate their performance and compare with modeling in LPILE. The lateral tests were conducted with the load applied in two orientations, either in line with the fins or rotated 45 degrees to the fins to assess any difference in performance in the fin orientation to the direction of loading. The effect of the direction of loading compared to the fin orientation proved to be small but existent, with the fin pile displacing less from the lateral load when loaded in between the fins. Additionally, the modeled deflected shape of the fin piles in the lateral test closely matched the observed deflected shape recorded by the shape array instrumentation. The models in LPILE provided results consistent with field observations in the lateral testing, bolstering the viability of fin piles as a prospective replacement to conventional deep foundations when lateral loading governs design.

Demonstration of Snow Removal Work by Wheel Loader in an Environment Surrounded by Obstacles

Snow removal work using construction equipment faces problems such as a shortage of skilled operators owing to the declining birthrate and aging population, work in dangerous areas, and accidents caused by a lack of concentration during long work hours. To improve the working environment, research and development of automation of construction equipment are actively conducted. Therefore, in this study, we aim to generate a driving path for wheel loaders for snow removal work in a work environment surrounded by obstacles, such as walls and fences. Furthermore, the proposed method considers the changing shape of the snow piles during the removal. We experimentally verified that snow removal could be performed using an actual wheel loader on the route generated by the proposed simulation.

An Experimental Investigation on Dike Stabilization against Floods

A flood protection dike blends seamlessly with natural surroundings. These dikes stand as vital shields, mitigating the catastrophic effects of floods and preserving both communities and ecosystems. Their design not only aids in controlling water flow but also ensures minimal disruption to the local environment and its biodiversity. The present study used a uniform cohesionless sand with d50 = 0.9 mm to investigate the local scour process near a single combined dike (permeable and impermeable), replicating a flooding scenario. The experiments revealed that the maximum scour depth is likely to occur at the upstream edge of the dike, resembling a local scour observed around a scaled-down emerged dike in an open channel. The scour hole downstream of the dike gets shallower as it gets smaller, as do the horseshoe vortices that surround it. Additionally, by combining different pile shapes, the flow surrounding the dike was changed to reduce horseshoe vortices, resulting in scour length and depth reductions of 48% at the nose and 45% and 65% at the upstream and downstream dike–wall junction, respectively. Contrarily, the deposition height downstream of the dike had a reciprocal effect on permeability, which can severely harm the riverbank defense system. The combined dike demonstrates their ability to mitigate scour by reducing the flow swirls formed around the dike. The suggested solutions can slow down the rapid deterioration and shield the dike and other river training infrastructure from scour-caused failures.

Study on three-dimensional penetration mechanism of snowflake pile

The indoor model tests of snowflake pile are carried out in this paper, the finite element method based on the coupled Euler-Lagrange (CEL) method is used, the effects of the cross-sectional shape of snowflake pile and the friction coefficient of the pile-soil action surface on the distribution of the plastic zone, displacement field and stress of the soil are considered. The results show that (1) the CEL method can better simulate the large deformation of the soil around the pile during the penetration of the snowflake pile; (2) the range of the plastic zone increases when friction exists at the pile-soil action surface, the shape effect on the plastic zone is negligible; (3) In the stress analysis, the friction coefficient has little effect on the peak strength of radial stress as well as vertical stress, there is a certain effect on the change of radial stress with vertical distance after the completion of pile compression, the shape effect has an effect on the change of radial stress with vertical distance (when μ = 0) and the change of vertical stress along the vertical distance, the change of radial stress with radial distance is negligible.

Topology optimization on periodic pile barriers considering material damping based on complex band diagrams

The frequency bandgaps of pile barriers that are periodically arranged can be used to isolate environmental vibrations. However, the viscosities of piles and soil were usually ignored. Moreover, the attenuation zone for the vibration isolation of traditional pile barriers was limited. To take the viscoelasticity of materials into consideration, the complex band diagram is introduced in this paper, and the effective attenuation zone is evaluated by the minimum imaginary part of the wavenumber. Single objective and multi objective topology optimizations are combined with the calculation of complex band diagram to maximize the width of the effective attenuation zone (EWAZ). The effects of different soil damping ratios and elastic moduli on the optimized pile shapes and EWAZ are analyzed. The optimization results show that the optimized pile shape is changed due to the existence of soil damping, and the EWAZ is larger with a larger soil damping. The excellent isolation effect of the optimized pile barrier is verified by frequency domain analysis in numerical 2D and 3D viscoelastic models. The obtained optimized pile structures show a better isolation effect than traditional structures. Moreover, compared with traditional band diagrams, the complex band diagram can quantitatively evaluate the attenuation performance, which saves computational resources.

Study on Muck Pile Shape of Open-Pit Bench Blasting Based on PFC

To study the influence of different resistance lines and rows delay intervals on the shape of the muck pile and the throwing distance of open-pit bench blasting based on the open-pit bench blasting test, two-dimensional particle flow code (PFC2D) is used for numerical simulation. The experimental and simulation data were compared and analyzed, and the error value was acceptable. Meanwhile, different resistance lines and row delay intervals are used to conduct numerical simulation analysis. The results show that the height change of the muck pile is directly proportional to the resistance line, and the rock throwing distance is inversely proportional to the resistance line change. The best resistance line is 1.75 m in the actual working condition, according to the effect of the muck pile. By fitting the relationship between the resistance line and rock throwing distance and blasting muck pile’s height, it is found that the relationship is nonlinear. By simulating different row delays, the optimal row delay time difference in the bench blasting model is determined to be 25 ms under similar working conditions. It provides a guiding significance for the blasting parameter design under similar working conditions.

Finite element analysis on dynamic behavior of sheet pile quay wall dredged and improved seaside subsoil using cement deep mixing

Sheet pile wall structures are commonly applied in coastal projects, particularly for the quay wall. This structural type normally is used in places where the ground has a low bearing capacity and is easily penetrable. Many sheet pile quay walls constructed in the past had low front water depth and did not satisfy the requirements of current standards. This issue could be addressed by improving the ground in front of the wall using cement deep mixing (CDM) and then excavating to increase the water depth in front of the wall. This paper numerically evaluated the dynamic behavior of the sheet pile wall after renovation. The numerical model was performed based on the finite element method (FEM) using the PLAXIS 2D program. The study focused on investigating typical parameters of the quay wall improved using the CDM, such as bending moment and displacement of sheet pile and the development of excess pore water pressure (EPWP) in the backfill. These results were compared to those of the quay wall without the CDM to elucidate the advantages of this method. In addition, the influence of some factors on the quay wall behavior, such as earthquake excitation characteristics, CDM area, and CDM strength, was also evaluated. The results demonstrated that the ground improvement using the CDM significantly decreased the bending moment and displacement of the sheet pile wall. The excitation characteristics did not affect the deformed shape of the sheet pile. With the constant CDM depth, the sheet pile displacement decreased with an increase in the improvement width until it reached a limitation. The increasing CDM strength also decreased the displacement of the wall until it raised a certain value. This demonstrated that this method was technically feasible, and it could be considered to study further by experiment before applying in practice.

Numerical analysis of laterally loaded barrette foundation

The effect of soil constitutive models, nonlinearity of the barrette material, loading direction as well as the cross-sectional shape and second moment of inertia on the response the barrette foundation under lateral loading is investigated in this research. The numerical analyses were conducted on a well-documented barrette load test using Plaxis 3D. The investigation results revealed that the response of the barrette is significantly affected by the direction of the applied load and nonlinear behavior of the soil and barrette materials. For rectangular, square, and circular piles with different cross-section areas and same second moment of inertia, the square and circular piles exhibit similar behavior but different from that of the rectangular pile. However, when these piles have the same cross-section area and different second moments of inertia, the behavior of rectangular pile is close to that of square pile when the load is applied along the x direction and is close to that of circular pile shape when the load is applied along the y direction.

The performance of T-shaped deep mixed soil cement column-supported embankments on soft ground

T-shape deep mixing (TDM) pile is a new method for soft ground improvement, which has an enlarged head at shallow depth, the pile shape analogous to the letter “T”. In this paper, three-dimensional numerical simulation is used to investigate the load transfer mechanism, failure pattern, and settlement behavior of TDM pile-supported embankments by dividing TDM pile into two parts: the enlarged head part and the pile body part and using the concrete model to simulate the TDM piles. The results reveal that the stress arches exist both in the embankment fill and the soil under the flange, and stress concentration will occur at the variable section of TDM piles, resulting in plastic yielding of the pile body, which in turn leads to load transfer to the soil, and additional stresses in the soil will cause additional compression of soft soil between TDM piles. Parameter analysis indicates that the load transfer, plastic zone, and post-construction settlement are related to the height of the enlarged head (H) and pile spacing (S), while pile length (L) only plays an important role in the post-construction settlement.

Numerical and Physical Modeling of the Effect of the Cone Apex Angle on the Penetration Resistance in Coarse-Grained Soils

The tip shape of penetrometers and piles has an important influence on the soil resistance mobilized during penetration. Blunt or flat tips typically generate greater penetration resistances, which can lead to refusal during in-situ testing and pile driving in the field. Results are presented from numerical and experimental investigations on probes with conical tips of varying apex angles to quantify the effect of the apex angle on the mobilized penetration resistance and associated failure mechanisms. Discrete element modeling (DEM) simulations were performed in unconfined and confined (i.e., stress-controlled) specimens to model shallow and deep penetration conditions, respectively. Centrifuge penetration tests were performed by quasi-statically advancing an instrumented probe to a depth-to-probe-diameter ratio of 16.7. The numerical and experimental results indicate that at shallow depths, the sharper tips mobilize smaller penetration resistances. In deep penetration conditions, the changes in penetration resistance with tip apex angle are less pronounced. Based on the results of the two investigations and values reported in the literature, a relationship characterizing the functional form between tip apex angle and normalized penetration resistance is proposed. A mesoscale analysis of the DEM simulation shows differences in the failure mechanisms induced by sharp and blunt tips: the zone where large particle displacements and stress changes occur is large and located below the tip for penetration with blunt tips, whereas the zone is smaller and located both laterally and below the tip for sharp tips.

Using an evolutionary heterogeneous ensemble of artificial neural network and multivariate adaptive regression splines to predict bearing capacity in axial piles

Accurately estimating the bearing capacity of piles is an onerous task in structural design task that requires a powerful computation model able to elucidate nonlinear impacts of geotechnical factors and the dimension and shape of piles. This study develops a novel heterogeneous ensemble artificial intelligence model, named intelligence multivariate neural network inference model (IMNNIM), to accurately and quickly predict bearing capacity of piles. The IMNNIM was created by integrating the equilibrium optimization algorithm (EO) into a combination of multivariate adaptive regression splines (MARS) and radial basis neural network (RBFNN). The predictive values of the IMNNIM were qualified by dynamically merging prediction information generated by MARS and RBFNN and then adjusting the associated weights and assigned tuning parameter values of the learner members. The performance of the IMNNIM was evaluated using data from 472 driven pile static load test reports. The experimental results using a 10-fold cross-validation method demonstrated the IMNNIM to be the most reliable model for predicting pile-bearing-capacity by achieving the greatest values of MAPE (7.24%), RMSE (90.92kN), MAE (67.98kN), and R2 (0.930) and the lowest standard deviation values. A t-test analysis method confirmed the IMNNIM as a superior tool for pile-bearing-capacity estimation.

Displacement Mapping of Point Clouds for Retaining Structure Considering Shape of Sheet Pile and Soil Fall Effects during Excavation

An entire large-scale retaining structure can be monitored by simulating a three-dimensional point cloud obtained by laser scanning. The behavior of a retaining structure composed of sheet piles according to excavation was analyzed by the displacement mapping method in this paper. The displacement errors can be generated due to inclined sections, U-shaped protrusions of sheet piles and cutting point clouds, and the fall and deposition of soil adhering to the sheet pile. Therefore, the analysis error was minimized by pretreatment of the point cloud considering the shape of the sheet pile before displacement mapping. For displacement mapping, the cloud to mesh (C2M) distance was calculated by segmenting the point cloud of the retaining structure into 5 rows and 20 columns, which have about 100 elements. Analysis of seven monitoring results from Day 0 to Day 35 was performed, and the maximum displacement occurrence point and the expansion of displacement with time were evaluated by displacement mapping. In an in-depth analysis after displacement mapping, it was possible to estimate the displacement variation in the vertical direction of a pile in which the excessive displacement occurred as well as the change pattern of the displacement in the horizontal direction of the entire pile head. A crack found at the top of a sheet pile occurred due to excessive displacement, which was verified by visual inspection.