Pile Quality Research Articles

Enhancing Quality Management of PHC Piles through Improved Driving Formulas: A Comprehensive Review and Analysis

In construction projects, conducting dynamic load tests on all piles proves impractical. Selective testing estimates bearing capacity, while the remaining piles rely on penetration depth for management. This approach, however, faces reliability issues due to varying conditions among piles. Technological advancements, such as non-contact hammers and sensors, have enhanced the accuracy of penetration depth measurements during final driving. Nonetheless, relying solely on penetration depth for construction and quality management remains problematic. This study, therefore, focuses on enhancing the use of driving formulas to improve pile quality management, particularly for the widely used pre-stressed high-strength concrete (PHC) piles. To improve pile quality management, existing driving formulas underwent review and refinement. Utilizing 258 dynamic load test data from various sites, the Hiley, Gates, and Danish formulas underwent validation through statistical analysis and graphical comparison. Enhancements to the Gates formula, achieved through curve fitting with actual data and the application of segment-based coefficients, demonstrated increased accuracy in bearing capacity estimation. These improvements offer a more reliable approach to pile quality management in construction projects.

Assessing sand sedimentation in drilling slurry using particle methods for ground excavation management

In the construction of cast-in-place concrete piles, residual sand portions in the drilling slurry that are not completely removed can significantly influence the strength and characteristics of the concrete piles. Understanding the sedimentation behavior of these sand portions during concrete placement is crucial to ensure pile quality. However, directly observing this process in real-time at construction sites is challenging, making it difficult to accurately assess the impact of the sand portions. When predicting the sedimentation of sand particles in drilling slurry, the conventionally used Stokes' equation can only express one-dimensional motion of a single particle size, but to accurately capture the real phenomenon, three-dimensional behavior must be considered. In this study, a numerical simulation method based on the particle method (MPS method) was used to visually evaluate the sedimentation process of sand in the drilling slurry. By modeling the drilling slurry and sand particles using the MPS method, the complex three-dimensional settling behavior of sand particles in the drilling slurry at both laboratory and full scales was successfully represented, demonstrating the effectiveness of this modeling approach. The MPS method allows for the analytical visualization of the three-dimensional sedimentation behavior, enabling real-time observation and quantitative evaluation of the sand sedimentation process. Using this method, the temporal evolution of the settling process of sand components in the drilling slurry can be tracked, providing valuable insights into factors that influence the quality of concrete piles. The results of this study demonstrate the potential of the MPS method for visually evaluating the settling behavior of sand components in drilling slurry. This approach offers a more accurate and reliable method for assessing the impact of residual sand on the strength and characteristics of cast-in-place concrete piles. By enhancing the understanding of this process, more effective foundation techniques can be developed to improve the safety and stability of structures built on soft ground, particularly in earthquake-prone regions where fine particles such as clay and silt pose additional challenges to construction practices.

The Effect of Setup Time in Geotechnical Resistance Factor of Driven Steel Piles in Alberta: a Case Study

Determining the bearing capacity of driven steel piles is a critical concern in geotechnical engineering particularly when constructing major structures in oil and gas and infrastructure projects in Alberta. To verify pile capacity, the pile driving analyzer (PDA) and static load tests (SLTs) are widely used. In recent years, PDA testing has become a regular part of pile quality assurance programs on projects and increasingly used as full-scale load tests. Several studies have shown that geotechnical resistance factor (GRF) values can be calibrated with the aim of PDA testing results which can help designers to potentially reduce the number and length of piles. Nevertheless, uncertainty remains regarding the extent to which the GRF value can be optimized following the implementation of the PDA. In this paper, a database of PDA tests and SLTs are compiled from several projects in Alberta, Canada. The primary objective of this study is to assess the impact of time on the recommended GRFs by several codes. To achieve this, the study employs a well-established probabilistic technique known as Monte Carlo Simulation (MCS) to quantify the influence of time, referred to as “setup time”. To enhance the assessment of setup time’s effect, the recorded bearing capacities are collected during two distinct time points: after the completion of pile installation or the end of drive (EOD) condition, and after a specific setup time at the Beginning-of-Restrike (BOR) condition. The results suggest that by taking into account the time impact, GRF values can be optimized, leading to an increase in factored pile resistance and ultimately resulting in a more cost-effective design process for steel-driven piles.

Comparative study of pile quality control techniques

This article delves into the critical realm of quality control in pile foundation construction, presenting a comprehensive exploration of both destructive and non-destructive testing methodologies. Focused on enhancing structural integrity and reliability, the study evaluates techniques such as concrete strength testing, core sampling, Cross-Hole Sonic Logging (CSL), and Pile Integrity Testing (PIT). Results from field observations conducted during construction of the Light Rail Transit (LRT) system in Astana showcase the effectiveness of non-destructive methods, with 1,896 bored piles subjected to rapid testing. Significant findings reveal that approximately 75% of tested shafts exhibited anomalies, emphasizing the necessity for meticulous quality control. The article concludes by advocating for the adoption of advanced quality assurance protocols to mitigate risks and ensure the robustness of pile foundations in construction projects.

A Hybrid Convolutional and Recurrent Neural Network for Multi-Sensor Pile Damage Detection with Time Series.

Machine learning (ML) algorithms are increasingly applied to structure health monitoring (SHM) problems. However, their application to pile damage detection (PDD) is hindered by the complexity of the problem. A novel multi-sensor pile damage detection (MSPDD) method is proposed in this paper to extend the application of ML algorithms in the automatic identification of PDD. The time-series signals collected by multiple sensors during the pile integrity test are first processed by the traveling wave decomposition (TWD) theory and are then input into a hybrid one-dimensional (1D) convolutional and recurrent neural network. The hybrid neural network can achieve the automatic multi-task identification of pile damage detection based on the time series of MSPDD results. Finally, the analytical solution-based sample set is utilized to evaluate the performance of the proposed hybrid model. The outputs of the multi-task learning framework can provide a detailed description of the actual pile quality and provide strong support for the classification of pile quality as well.

Enhancing static load test of pipe pile composite foundation with innovative elastic cushioning technology

Pipe piles have been widely used in composite foundation treatment by virtue of the advantages of assembly line production, easy control of pile quality, fast construction, high bearing capacity of single pile and green environmental protection. By introducing elastic cushion in the static load test method of pipe pile composite foundation, and using theoretical analysis and field test to study the change rule of settlement, pile-soil stress ratio and pile top stress of pipe pile composite foundation with different cushion stiffness. It is concluded that it is feasible to replace the sand cushion layer recommended by the current specification with elastic cushion layer. The study shows that the elastic cushion method of static load test of pipe pile composite foundation is closer to the bearing state of real working condition. The elastic cushion has better pile-soil stress adjustment effect, which is more responsive to the stress adjustment effect of actual engineering cushion, and the elastic cushion provides an improved method for the static load test method of composite foundation.

Load-Bearing Characteristics of PHC Piles Constructed by the Inner Digging Method Based on Ultimate Load Testing and Numerical Simulation

This paper studies the load-bearing characteristics of two prestressed high-strength concrete (PHC) pipe piles constructed by the medium mid-digging and hammering methods. The ultimate load tests and numerical simulations of the pipe piles constructed by both methods were carried out to analyze the ultimate lateral resistance, and ultimate resistance performance characteristics of the two pipe piles and the influence of the wall thickness of the pipe piles on the bearing performance. The test results show that the pipe pile constructed by the middle inner digging method has a higher pile quality. The single pile bearing capacity of the pipe pile constructed by the middle inner digging method is 50% higher than that of the common hammering method. The enlarged part of the pile end has an obvious effect on improving the bearing capacity. The settlement of the pipe pile constructed by the middle inner digging method is smaller than that of the hammering method. The large diameter pipe pile constructed by the middle inner digging method usually shows characteristics of the end-bearing pile. The resistance of the pile end accounts for 40–50% of the top load. The numerical simulation results agree with the field test and are compared and discussed. The simulation results show that when the bearing capacity of the pile is provided by the pile side frictional resistance, the influence of the pile wall thickness on the bearing capacity is insignificant. When the top pile load is close to the bearing capacity of the pipe pile, the influence of the pipe pile wall thickness on the bearing capacity is greater.

Quality Control Measures of Bored Pile in Bridge Construction

In order to improve the quality of bored piles in bridge construction and ensure the overall quality of the bridge, we analyzed a series of problems in the construction process of bored piles, then propose corresponding quality control measures, in hopes of improving quality control of bored piles in bridge construction in our country.

Experimental Study on the Flexural Behavior of Connected Precast Concrete Square Piles

Part of deep foundation pit support engineering needs to select connected precast concrete square piles (CPCSPs). Under the premise that the quality of precast concrete square piles (PCSPs) meets engineering requirements, the quality of CPCSPs becomes the key factor to ensure the safety of foundation pit support structures. This paper puts forward a new connection technology of CPCSPs and carries out the flexural behavior experiment of unconnected precast concrete square piles (UPCSPs) and CPCSPs. The distribution of crack and strain on different surfaces of UPCSPs and CPCSPs are measured by carbon fiber composite strain sense optical cables, glass fiber composite strain sense optical cables, and fixed-point polyurethane strain sense optical cables. The anti-crack load, ultimate load, bending moment, and flexural deformation of UPCSPs and CPCSPs are measured. The experimental results of UPCSPs and CPCSPs are compared. The results show that the anti-crack strength of CPCSPs is greatly increased while the flexural deformation of CPCSPs is decreased before the occurrence of crack. With the development of crack (failure stage), the outside areas of hoop steel plate exhibit cracks. At this moment, the strength of CPCSPs is no longer controlled by the strength of middle areas. The ultimate strength of CPCSPs is basically equivalent to that of UPCSPs. The ultimate bending moment of CPCSPs is higher than its design value (about 66%∼76%). The selection of CPCSPs in the design of foundation pit support has good reliability.

Capabilities of auxiliary techniques for low strain impact testing of piles foundations

Introduction. An increase in the complexity of tasks arising from the quality control of geotechnical structures ultimately increases the role of indirect methods as part of the survey set. Low strain impact testing of piles length and integrity is currently one of the most common non-destructive geophysical methods used in the state diagnostics of foundations. The capabilities and limitations of the method are associated with the peculiarities of its basic theoretical model describing the propagation of elastic waves in a thin rod. In this regard, specialists often have recourse to the auxiliary techniques of field research.Aim. To inform test engineers, designers and employees of supervisory organizations about the potential of auxiliary methods for the low strain impact quality control of pile foundations.Methods and materials. The features of the theoretical model of the low strain impact pile quality control, as well as the associated capabilities and limitations of the method are described. The auxiliary methods of data collection and analysis were used for the survey of pile foundations, including those in the composition of existing structures.Results. The results of the work are represented by additional information obtained about the foundations surveyed using the auxiliary methods of data collection and analysis. An alternative arrangement of sensors relative to the surveyed structure was used for determining the depth of piles in the composition of grade beam footings and existing structures. The common shot point profiling (ultra-seismic method) was used to assess the velocity of rod wave propagation in the body of the structure. The options of data presentation in the parallel seismic method were used to demonstrate its potential for the quality control of foundation concrete.Conclusion. The auxiliary methods of data collection and analysis used in the low strain impact survey of pile foundations can significantly increase the reliability of conclusions about the depth and integrity of a structural material.

Research on the Soil-Plugging Effect on Small-Diameter Jacked Piles through In Situ Testing and DEM Simulation

Small-diameter jacked piles are widely used in civil engineering. The formation and development of the soil-plugging effect and surface frictional behavior of jacked piles have a high impact on the construction process and pile quality. Clarifying the developmental pattern of the soil-plugging effect and the change law of frictional force forms the premise of scientific construction and construction quality. Firstly, we carried out two groups of in situ tests on the small-diameter jacked piles, recording the relationship between penetration depth and resistance force. Then, the discrete element method (DEM) was used to analyze the mechanical behavior of the small-diameter jacked piles during the construction process. The particle flow code (PFC) 2D was used to carry out the DEM simulation. The research results show that pile resistance exhibited an irregular development trend as the construction process proceeded. There is a sudden change in pile resistance when the pile tip reaches the interface of certain soil layers. Both tests revealed the same phenomenon, yet both occurred at different depths. The DEM analysis showed that plug sliding was the main reason for the above phenomenon. The difference in strength and stiffness of adjacent soil layers causes the soil plug to slide, leading to a sudden change in pile resistance. When the upper layer is soft and the layer below is hard, this phenomenon is especially obvious. This also leads to a difference in the location of the sudden change in pile resistance between the two groups of tests. The research results of this paper can be helpful for revealing the relationship between the soil-plugging effect of small-diameter jacked piles and the development of pile resistance and also provides a reference for relevant engineering construction and design.

Development of an Algorithm for Determining Defects in Cast-in-Place Piles Based on the Data Analysis of Low Strain Integrity Testing

Low strain integrity testing for pile quality control, based on the analysis of elastic waves, is one of the most common methods, due to its high efficiency. However, it also has a number of limitations that should be taken into account during pile testing. For additional study of the method and its effectiveness, an experimental site was constructed, consisting of ten cast-in-place piles with embedded defects. When analyzing field data, pile defects were not identified. For further analysis of the problem, as well as for interpreting the results and identifying pile defects, a cluster analysis method, the so-called ANN-classifier, is proposed. This paper describes the results of creating an algorithm for the recognition of defects and their localization in cast-in-place piles. It is proposed that use of the characteristic points of the spectrum of the signal as the input vector of the ANN classifier, and the type of pile defect as the output vector, is optimal. The results of the study led to the conclusion that the ANN-classifier can be used as the main tool for automatic interpretation of the results obtained by low strain integrity testing.

Detection and Function of Elastic Wave Tomography of Foundation Piles of High-Rise Buildings under the Background of Internet of Things

Foundation piles are a widely used foundation form for high-rise buildings. Its main function is to reduce the settlement of buildings. In recent years, in areas with good upper soil conditions, in order to reduce the amount of earthwork excavation and transportation, more and more engineering buildings use foundation piles. Therefore, the status of foundation piles in construction projects is becoming more and more important. The high-rise building foundation pile project belongs to the underground concealed project. In the construction process, it is greatly affected by factors such as construction technology and geology. After the construction is completed, it is difficult to observe the changes inside the foundation pile with the naked eye as time goes by. A series of problems such as building collapse, settlement, and cracking often occur, thus affecting normal use and causing some safety accidents. In order to solve these series of problems, this paper proposes an elastic wave tomography detection method. It performs imaging inversion calculation on the inside of the foundation pile, and many methods are used in it. In the canonical Gaussian-damped Newton method in tomography, its iteration rate is 3.5% higher than that of the canonical Gaussian-Newton method, the convergence speed is accelerated, the accuracy is high, and the error is small. In the process of detection, this method is more suitable to detect the integrity and quality of foundation piles.

Seismic Response Evaluation of High-Steep Slopes Supported by Anti-Slide Piles with Different Initial Damage Based on Shaking Table Test.

In order to study the instability development process of the slope reinforced by anti-slide piles under earthquake conditions, the dynamic response characteristics of the slope are usually taken as the main characteristics, and the model test and numerical simulation are the main research methods. In this paper, a shaking table model test is designed and completed to investigate the influence of anti-slide piles with different initial damage on the failure mode of high and steep slope under earthquake conditions. The changes in velocity, strain and natural frequency during slope vibration are tested in combination with cloud maps when sinusoidal waves of different accelerations with a peak value of 5 Hz are applied. Thus, the differences of slope failure development process and dynamic response characteristics are obtained. The experimental results show that the anti-slide pile with different initial damage has obvious influence on the slope instability process. Under the condition of good anti-slide pile quality, the failure development of the slope behind the pile is limited to soil sliding on top of the slope, slope sliding and overburden sliding; the front slope foot of pile mainly forms shear belt and local sliding. With the decrease in the initial mass of the anti-slide pile, the slope failure develops into topsoil sliding, slope sliding and deep integral sliding; analogously, the failure of the slope in front of the pile develops into a whole slip along the slip belt. The natural frequency cloud map can directly reflect the damage location of the slope, and the frequency change rate is positively correlated with the cumulative shear strain. It shows that the macro-failure characteristics of the model slope change well when the natural frequency is used as the sensitive index to measure the influence of vibration on the model slope. The threshold value of the natural frequency change rate can distinguish different development stages of the slope; 1% is the threshold value of stage II, and 1.5% is the threshold value of stage III.

Evaluation of the quality of bored piles by seismoacousticand interwell ultrasonic methods

Evaluation of the quality of bored piles by seismoacousticand interwell ultrasonic methods

Determination of concreting quality of bored piles by CHA method

In the presented article, the authors consider the issues of quality control of bored piles in the practice of bridge construction. The importance of quality control of these pile structures is emphasized. The basic requirements for quality control in the production of construction works and their acceptance are presented. A description of the control method is given. As a practical example, the results of quality control of the execution of bored piles by the method of cross well ultrasonic scanning at the bridge over the river Chusovaya. An assessment of the state of bored piles after testing is given.

Research on detection technology of squeezed branch and disk pile under boulder geological condition

The detection methods of the cavity and cavity size and pile quality of squeezed branch and disk pile are not perfect. Based on the 65 pier of a viaduct in Zhongshan City, this paper uses caliper, cross hole acoustic wave method, core pulling method and tube wave method to detect the squeezed branch and disk pile, and compares and analyzes the advantages and disadvantages, applicable conditions and detection results of each method. It can be seen from the test results that both caliper and cross hole acoustic wave method can detect the length of squeezed branch pile, while core pulling method and tube wave method can detect the quality of pile body and the thickness of sediment at the bottom of pile. The test results are basically consistent and verified with each other, and the specific data such as the length of branch and the thickness of sediment are slightly different. In this paper, caliper, cross hole acoustic method, core pulling method and tube wave method are verified and analyzed to provide ideas and support for the later detection of squeezed branch and disk pile.

Detection of Defects in Bored Piles By Non-Destructive Methods On LRT Construction Site

This article presents the detection of defects in bored piles with cross-section 1.2÷1.5 m and length 1÷53 m. PIT and Cross-hole Sonic Logging (CSL) methods were used to detect defects in piles. These works were carried out in the city of Nur-Sultan on LRT construction site. Integrity inspections performed after installation are often the most reasonable alternative available to assess the pile quality. This paper discusses the similarities and differences, also advantages and disadvantages. Both Cross-hole Sonic logging and impact echo integrity testing indicated defects in several pile. Subsequent coring confirmed these defects. The results of the two test methods are presented and compared with each other.

Assessment of the Contact between Piles and Soil via the Dynamic Attributes of Acoustic Signals

Abstract—The low-strain impact method is one of the most commonly used nondestructive geophysical methods in pile integrity testing. Data analysis of the low-strain method in the frequency domain allows a researcher to obtain additional information about a foundation. The authors of this article propose a methodology for assessing the contact of piles with soils based on an analysis of the dynamic attributes of the frequency response. Conclusions drawn from using the above-described method can be used by engineers to study the quality of piles and to plan direct static load tests to determine the bearing capacity of piles.

Research on the Method of Measuring the Elevation of Bored Pile Head by Pressure

The detection of pile top elevation is a key link of pile quality control. Based on the jacking principle, this paper analyzes the shortcomings of the existing measurement methods, innovatively introduces the pore pressure to consider the influence of the change of slurry level, effectively proposes an improved pressure detection method, and designs a pressure detection device. The device is simple and easy to operate, which can provide reference for the field research on the elevation of the top of bored pile.