Pile Method Research Articles

Study on bearing characteristics of single pile in heterogeneous layered foundation

Based on a project in Lanzhou City, Gansu Province, China, the bearing and internal force characteristics of 2 piles of different lengths under vertical load were tested and analyzed by using BOFDA technology and anchor pile method static load test. The results show that long pile has higher vertical bearing capacity and greater elastic working range, but the axial force of long pile and short pile has the same trend. The lateral friction resistance of the soil layer around the pile plays a role earlier than the pile tip resistance, and the lateral friction resistance of the upper soil layer plays a role earlier than the lower soil layer. The increasing amplitude of lateral friction resistance in different soil layers is also different. The settlement of short pile top is mostly caused by the displacement of pile bottom, and the pile tip resistance is more affected by the pile tip sediments. The relationship between pile end resistance and displacement under the influence of sediments can be analyzed by three-fold line model.

Thermo-Mechanical Coupling Load Transfer Method of Energy Pile Based on Hyperbolic Tangent Model

By employing the hyperbolic tangent model of load transfer (LT), this paper establishes the thermo-mechanical (TM) coupling load transfer analysis approach for an energy pile (EP). By incorporating the control condition of the unbalance force at the null point, the method for determining the null point considering the temperature effect is enhanced. The viability of the presented method is validated through the measured outcomes from model experiments of energy piles. A parametric investigation is conducted to explore the impact of the soil shear strength parameters, upper load, temperature variation, head stiffness, and radial expansion on the axial force, strain, and displacement of the energy pile under thermo-mechanical coupling. The results suggest that the locations of the null point and the maximum axial force are dependent on the constraint boundary conditions of the pile side and the two ends. When the stiffness of the pile top increases, axial stress and displacement increase, while strain decreases. An increase in the drained friction angle leads to an increase in axial stress under thermal-load coupling, but strain and displacement decline. The radial expansion has a negligible influence on the thermo-mechanical interaction between the pile and the soil.

PELAKSANAAN PEKERJAAN STRUKTUR BAWAH BANGUNAN GEDUNG SERBAGUNA GELANGGANG GENERASI MUDA MAJALENGKA

The Majalengka Regency Youth Center Development Project is an important historical milestone for infrastructure development in the Majalengka Regency area. The concept of an oval-shaped building like a stadium gives uniqueness to the design of the foundation of this building. Basically, the substructure is a very vital component for the success of a building, so the author is interested in looking further into the substructure, especially in work methods or work implementation. This research uses a qualitative approach, which can be interpreted as directly describing the work of the lower structures in the project which is used as the research object. The implementation of the lower structure work starts with the piling work and then continues with the pile cap work, carried out in stages using a zone system. In the realization of the implementation of the lower structure work on the GGM project, namely the piling work starting from site preparation, mobilization and set up of HSPD piling tools, measuring pile points, driving piles using the hydraulic jack-in pile method, testing piles, and pile head treatment, continued with the implementation of pile cap work starting from preparation, measurement and bow plank, soil excavation, installation of formwork, reinforcement and casting.

Performance and behaviour of prebored and precast pile with floating pile tip based on A full-scale field static axial load test

This study investigates the load transfer mechanism of a Prebored and Precast pile (PP pile), constructed installed in accordance with the rules applicable to the Hyper-Straight pile method (HS pile), in clay soils. While the HS pile method, developed in Japan, typically results in high bearing capacity piles in various soil types, its performance in clay soils remains understudied. Our research focuses on a unique configuration where the pile tip “floats” within a soil–cement mixing (SCM) column near the bottom of the borehole, a condition that significantly influences the system’s performance.We conducted a full-scale axial static load test on a 500 mm diameter and 140 mm thickness straight shaft precast prestressed concrete spun pile. The pile was instrumented with vibrating wire strain gauges (VWSG) and displacement measuring devices (tell-tales), embedded 15 m deep in a 750 mm diameter SCM column (15.75 m long). The pile tip was positioned 75 cm above the bottom of the borehole, creating a floating condition within the SCM material. Both the pile and the surrounding SCM were instrumented to provide comprehensive data on the system’s behavior.The test involved two loading–unloading cycles. The 1st Cycle reached a maximum load of 3627 kN, resulting in a 75.52 mm pile head settlement. The 2nd Cycle achieved a maximum load of 4181 kN, leading to a 118.04 mm pile head settlement. In the 1st Cycle, we observed upward movement of the SCM material around the shaft after the pile skin friction reached its maximum capacity. Stress at the pile tip exceeded the unconfined compressive strength of the SCM material, indicating potential local shear failure.Contrary to expectations based on HS pile performance in other soil types, the ultimate bearing capacity of our pile was determined to be 2000 kN, comprising 545 kN from skin friction and 1455 kN from end bearing. This result aligns more closely with the behavior of conventional bored pile rather than the “hyper” capacity typically associated with HS pile. Consequently, we classify our pile as a “prebored and precast pile,” like systems used in China and Korea.Our study concludes that the strength of the SCM material and the pile tip location significantly influence the pile’s bearing capacity in clay soils. These findings highlight the critical impact of soil type on the performance of piles constructed using the HS method. The observed behavior suggests that current design methods for HS pile may overestimate capacity in clay conditions, emphasizing the importance of soil-specific analysis and testing.This research contributes to the understanding of PP pile behavior in clay soils, providing valuable insights for geotechnical engineers. It underscores the need for refined prediction models and design methods specific to these soil conditions, paving the way for more accurate and reliable foundation designs in regions with predominant clay soils.

Comparison of Liquefaction Damage Reduction Performance of Sheet Pile and Grouting Method Applicable to Existing Structures Using 1-G Shaking Table

This study conducted 1-G shaking table tests to compare methods of reducing liquefaction damage during earthquakes. The sheet pile and grouting methods were selected as applicable to existing structures. Model structures were manufactured for two-story buildings. A sine wave with an acceleration of 0.6 g and a frequency of 10 Hz was applied to the input wave. Certain experiments determined the effect of various sheet pile embedded depth ratios and grouting cement mixing ratios on reducing structural damage. The results confirmed that when the sheet pile embedded depth ratio was 0.75, the structure’s settlement decreased by approximately 79% compared to the control model. When the grouting cement mixing ratio was 0.45, the structure’s settlement decreased by approximately 85% compared to the untreated ground. In addition, the sheet pile method suppressed the increase in pore water pressure compared to the grouting method but tended to interfere with the dissipation of pore water pressure after liquefaction occurred. Additionally, comparing the effect of each method on reducing liquefaction damage revealed that the grouting method resulted in less settlement, rotation of the structure, and pore-water-pressure dissipation than the sheet pile method. Overall, the grouting method is more effective in reducing liquefaction damage than the sheet pile method. This study forms a basis for developing a liquefaction-damage reduction method applicable to existing structures in the future.

Effect of pile driving induced ground vibrations and stress distribution to close settlements: a case study

The pile method, applied in the foundational operations of construction to enhance soil-bearing capacity, is utilized in locations with insufficient soil support. Its purpose is to reinforce the foundation and improve soil stability before constructing a structure. In this study, vibrations occurring during the application of Vibrex-type piles for foundation reinforcement in a construction project located in the Konak district of Izmir Province were measured at various distances from the measurement points. The study further explored the influence of pile application on soil stability, considering the geomechanical properties of the site’s soil structure. The analysis of the study’s graph indicates that stress and vibration velocity remains at optimal levels, suggesting favorable working conditions.

Penetration mechanism of open-ended pipe piles under jacking and driving methods

Different pile penetration methods will cause different pile penetration results. Therefore, it is very necessary to study the pile penetration mechanism under different pile penetration methods. In this paper, numerical simulations using the discrete element method (DEM) are carried out to investigate the meso-scopic mechanism of pipe pile penetration under jacking and driving methods. The mechanism is comprehensively compared and analyzed in terms of particle movement, changes in the force chain, displacement changes, resistance of penetration pile, soil lateral stress and soil vertical stress. Results show that the height of the soil plug in the jacked pile is lower than that in the driven pile. The degree of contact force chain at the bottom of the soil plug in the driven pile is slightly higher than that at the bottom of the soil plug in the pile of the jacked pile. The total resistance of the driven pile greater than that of the jacked pile. Within a certain distance below the pile tip, the jacked pile affects the vertical stresses of the soil in this area to a greater extent than the driven pile. Then, parametric sensitivity analysis is performed, which captures the effects of the penetration velocity in the jacking method and the hammering frequency in the driving method. This study can provide a reference for the selection of the penetration method of pipe piles in actual projects.

A contour detection method for bulk material piles based on cross-source point cloud registration

A contour detection method for bulk material piles based on cross-source point cloud registration

Failure mechanism and control technology of high-stress red shale roadway in Kaiyang phosphate mining of China

To solve the supporting problem of high-stress red shale roadway in Kaiyang phosphate mining area, the mechanical properties and microstructure of red shale are studied. The results show that the compressive strength of the red shale is related to the bedding angle, and the strength of the 0° samples is the highest, and the strength of the 60° and 30° samples decreases gradually. With comprehensive consideration, the composite supporting method of cantilever piles and grid arch is adopted. Combining the numerical simulation and theoretical calculation, the parameters of cantilever pile with interval distance of 5 m and rock-socketed depth of 500 m are more reasonable. The monitoring results show that the roof subsidence was controlled within 250 mm, and the floor heave was within 100 mm, which could effectively control the severe deformation of the roadway and also is of great significance to the safe mining of phosphate resources.

Enhancing innovation competitiveness spun pile method risk: Insights from ISO 56002:2019

Enhancing innovation competitiveness spun pile method risk: Insights from ISO 56002:2019

Study on the structure parameters and design method optimization of blade-type screw steel pipe pile

The rationality of structure parameters of the blade-type screw steel pipe pile is the major factor in determining the safety, applicability, and economy of a pile foundation, but the existing design methods have not defined the specific approaches to calculating structure parameters of blades and steel pipes. To address this issue, an analysis of the strength theory was performed on spatial helical blades, revealing the ratio of blade width to steel pipe radius as the core index to do the structure parameters design of blade-type screw steel pipe pile and established a mathematical calculation model between the vertical bearing capacity of single pile and a. The rational value of a is 2.0–3.0 using numerical calculation. The correlation between blade thickness and wall thickness of steel pipes was determined using the force analysis based on the synergy between blades and steel pipes. Then the structure parameters design method of blade-type screw steel pipe pile with coordinated parameters was proposed. The rationality and superiority of this design method were verified by comparing the existing test data and the finite element simulative analysis. Based on this design method and the current specifications, such as the Technical Code for Building Pile Foundations, a safe, applicable, and economical optimization design method and flow of blade-type screw steel pipe piles were further proposed for engineering design reference.

Optimization of Uplift Piles for a Base Plate Considering Local Anti-Floating Stability

This paper focuses on the optimization of uplift piles for a base plate considering local anti-floating stability. According to the force characteristics of the base plate subjected to buoyancy, a bi-directional evolutionary structural optimization (BESO) process is proposed. The optimization process takes the pile length as the design variable and the pile end displacement as the sensitive coefficient. The proposed process is conducted with FLAC3D to optimize the length of each uplift pile, including two cases with different pile diameters and spacing. The optimization process shows that the deformation degree of the base plate is significantly reduced when the piles are adopted with large diameters and sparse spacing, and oscillates at a low level when the piles are adopted with small diameters and dense spacing. Consequently, the design method of uplift piles considering the local anti-floating stability is proposed by referring to the optimization results of two cases. Finally, the proposed design method is applied to a practical project, and the original design of the uplift piles is optimized. The comparison results show that the deformation degree of the base plate of optimization designs is significantly lower than the original design.

Frequency-amplitude decoupling in the Gentle Driving of Piles (GDP) method: shaker design and experiments

Frequency-amplitude decoupling in the Gentle Driving of Piles (GDP) method: shaker design and experiments

The effect of high-frequency torsion in vibratory pile installation: the Gentle Driving of Piles method

The effect of high-frequency torsion in vibratory pile installation: the Gentle Driving of Piles method

Soil-cement columns for high-rise buildings: design–testing–construction–monitoring: A case study of green solution in Vietnam

Soil cement columns (SCCs) are commonly used to reinforce soft ground to support roads and railway embankments, or to withstand horizontal pressure for deep excavations. This study presents another application of SCCs as load-bearing foundations for high-rise building projects. SCCs with a diameter of 800 mm, length of 10 m, cement content of 350 kg/m3, and an unconfined compressive strength (UCS) of 3.6 MPa were applied. In this study, five single columns and one group constituting two columns were constructed, and core drilling and axial static load tests were conducted. The test results indicated that the SCC could achieve a load of 1,650 kN for a single pile and 3,300 kN for the group constituting two columns. In total, 1,123 columns were designed and constructed for this project. Compared with conventional reinforced concrete pile methods, a project using SCC could save 30 construction days and 20% of the total cost. Moreover, SCC can be considered a green and environmentally friendly foundation solution because it does not use concrete or steel materials and does not produce waste soil.

Cost and Duration Analysis on the Variation of Soil Improvement Method on Port Development at West Java

Several port facilities, including a container terminal, was built in a port reclamation project in Subang Regency, West Java. The soil improvement method employed in most reclamation projects usually involves prefabricated vertical drains, deep cement mixing (DCM), pile method, etc. This study aims to analyze the varying soil improvement methods, specifically deep cement mixing method and the pile method using bamboo piles and compare them for work efficiency based on time and cost. The methodology used in this study included literature studies, and qualitative analysis based on keyword. Based on the analysis results on the aspect of duration, the preparation, installation/design, and installation of barriers with geotextile reinforcement, backfilling, and pavement for the DCM and pile method required 743.15 days and 763 days respectively. The cost review, which referred to the unit price of Minister of Public Works and Housing Regulation No. 1 year 2022, found that the DCM method requires higher costs than piles. The analysis results also shown that the DCM method is more efficient due to the process in the DCM method has a fast installation duration, does not require many human resources on one job, and the materials used are environmentally friendly and more durable in water.

Research on spontaneous combustion characteristics and high temperature point prediction method of rectangular coal pile

ABSTRACT In order to prevent and control the spontaneous combustion phenomenon of rectangular coal pile under the coal storage and transportation scenario, the spontaneous combustion process of rectangular coal pile was simulated based on the experimental platform, the spontaneous combustion temperature change characteristics of rectangular coal pile were obtained, a coal spontaneous combustion prediction model was constructed based on the proposed prediction method. The results show that the height of the coal pile of 30 cm is a demarcation line, the temperature change of the upper measurement point is more consistent, but the lower measurement point has a greater variability, and reaches the ignition point in a shorter time, the peak temperature is higher, which further exacerbates the spontaneous combustion of the coal pile; At 3 h the coal pile formed an initial high-temperature region, and at about 14 h the pile was in a state of complete spontaneous combustion; The prediction method using temperature data from surface measurement points as model inputs is more feasible; All three models have good robustness and generalization, and the specific order of merit is GA-BP > GA-RF > GA-SVR. The study has an important guide for the safe, green and economical development of coal transportation and storage.

Finite Element Analysis of Load-Bearing Characteristics and Design Method for New Composite-Anchor Uplift Piles

This paper introduces a new type of uplift pile known as the composite-anchor pile, which employs a composite anchor composed of steel strands, grouting materials, and steel pipes as the main reinforcement. This paper extensively analyzes this pile’s load-bearing capacity and deformation characteristics through full-scale field tests and three-dimensional finite element numerical simulations. The results show that the composite-anchor pile has a more even distribution of stress, and its endurance and mechanics performance are better than others. Furthermore, this study utilizes a three-dimensional finite element refined model that has been validated using on-site test results to examine the influence of key parameters, such as the pile diameter, the number of composite-anchor cables, and the diameter of steel strands, on the load-bearing capacity of uplift piles. Building upon these findings, this paper introduces a calculating method to determine the bearing capacity of composite-anchor piles, thereby addressing the existing gap in this field.

Analyzing Embankment Displacement: PVD and Vacuum Consolidation with Sheet Pile Protection

The global widespread adoption of Prefabricated Vertical Drains (PVD) in conjunction with vacuum consolidation is driven by its robust and cost-efficient attributes. However, this construction method is not without challenges, as it has been linked to substantial displacements, posing risks to adjacent structures. Addressing such concerns in a Vietnamese road construction project, this study focuses on the innovative contribution of sheet pile protection as a highly effective solution. Utilizing numerical analysis with an anisotropic model, we examine the impact of sheet pile protection on embankment displacement. Through comparative analysis with field data, our study demonstrates the remarkable efficacy of the sheet pile method in significantly reducing both vertical and lateral settlements. Acting as a protective membrane, it effectively counters suction from the PVD vacuum zone. These findings make a substantial contribution to the field, providing engineers handling similar structural protection scenarios with invaluable insights and a novel approach to mitigating displacements associated with PVD and vacuum consolidation.

Estimation of the installation torque–capacity correlation of helical pile considering spatially variable clays

In the offshore fields, helical piles are increasingly deemed to constitute suitable tools for anchoring floating structures and wind turbines. A large number of studies have been published to explore the installation torque–capacity correlation, and most of them are conducted in a deterministic manner. However, natural soils are inherently spatially varying, and analyses taking such variation into account might be closer to the reality. To address this issue, this paper examines the installation and uplift process of helical piles considering spatially varying soils via three-dimensional large deformation random finite element analyses within a Monte Carlo framework. Computed values of the installation torques and the uplift capacities compare well with the results in existing publications, therefore verifying the applicability of the numerical model. Spatially varying soil strength is mapped through the random field, followed by Monte Carlo simulations conducted to determine the torque–capacity correlation in random soils. The results suggest that the torque–capacity correlation might be misestimated once the spatially random soil properties are overlooked. Besides, probabilistic assessments of the pile torque–capacity correlation are performed, which may be of great interest to engineering practitioners in the design method of the helical pile.