Search Results (75)

Driven piles are a common geotechnical solution for foundations in weak soil profiles. However, hammer impacts during the driving process can generate excessive levels of ground vibration, which, in extreme cases, can affect nearby structures and people. Due to the complexity of wave propagation in soils, the accurate prediction of these vibrations typically requires advanced numerical modeling approaches. To address this challenge, a surrogate modeling framework was developed by integrating Artificial Neural Networks (ANNs) and Extreme Gradient Boosting (XGBoost), trained on a synthetic dataset generated from an experimentally validated numerical model. The proposed surrogate model enables the rapid prediction of ground vibration characteristics, including peak particle velocity (PPV) and frequency content, across a broad range of soil, pile, and hammer conditions. In addition to its predictive capabilities, the tool allows users to design a specific mitigation measure (open trench) and compare the vibration levels with international standards. Experimental validation confirmed the model’s ability to replicate field measurements with acceptable accuracy. The expedited prediction tool is available as supplemental data and can be used by other researchers and technicians for quick and accurate ground vibration predictions. Full article

Aerobic composting is widely used for the degradation of organic matter, simultaneously reducing the presence of antibiotic resistance genes (ARGs) in swine manure. However, the phenomenon of abundance rebound or even enrichment of ARGs is still a problem. The effect and mechanism of humus soil (Hs) on ARG reduction by adding it into the piles (0% for the control group (CK); 10% for S1 group; 20% for S2 group; and 30% for S3 group) after the thermophilic phase of composting was investigated. The results indicated that Hs promoted organic matter degradation and nitrogen loss. During days 15–36, the greatest reduction of 69.91% in total ARG abundance was observed in S2, while the abundance rebounded by 222.75% in CK and decreased only 13.71% in S3. With the 20% Hs addition, 85.42% abundance reduction for mobile genetic elements (MGEs) and 100% removal rates for aadA5, aadA9, sul1, sul2, and tetX were achieved. Moreover, the addition of Hs immediately changed the bacterial community structure of the substrate and varied the bacterial community successional direction in the treatments. Additionally, significantly positive correlations (|r| > 0.6; p < 0.05) were found between the top 20 genera and ARGs. The potential host bacteria for ARGs changed from Lactobacillus, Fermentimonas, Pusillimonas, and Ruminofilibacter in CK to Lactobacillus, Romboutsia, and Streptococcus in S2, highlighting the shift and reduction in host bacteria driven by Hs, which, in turn, influenced the abundance variations in ARGs. This study verified the feasibility of inhibiting the rebound of ARG abundance effectively by influencing the microecological niche in the pile, offering an approach for promoting a reduction in ARGs in animal wastes. Full article

This article proposes a novel tube foundation intended for use under transmission line poles. The glass fibre reinforcement polymer (GFRP) piles were driven into sand. A steel tube pole, approximately 6 m high, was mounted on the foundation. The analysed foundations were designed as a monopile to be implemented in the construction of low- and medium-voltage overhead transmission lines. Experimental field tests of innovative piles made of the composite material were carried out on a 1:1 scale. The aim of this work was to develop an isotropic material model treating the GFRP composite as homogeneous. This approach does not fully reproduce the anisotropic behaviour of the composite, but it allows for the engineering design of structures made of the composite material. Laboratory tests in the form of a static tensile test on the samples and a tensile test on the rings cut from a hollow section were performed. The results of the experimental tests and FEM models of the GFRP rings and monopile embedded in sand were compared. The ultimate limit state (ULS) and serviceability limit state (SLS) of the analysed pile were assessed as 14.4 and 9.6 kNm, respectively. The developed numerical model, based on FEM, allows for the load-bearing capacity of the monopile made of GFRP to be reliably determined. From an engineering point of view, the developed numerical model of the GFRP material can be used to calculate the pile load-bearing capacity using engineering software that has limited capabilities in defining material models. Full article

The increasing global demand for renewable energy has resulted in a high interest in wind power, with offshore wind farms offering better performance than onshore installations. Coastal nations are thus, actively developing offshore wind turbines, where monopiles are the predominant foundation type. Despite their widespread use, the effects of monopile installation methods on the overall foundation behaviour are not sufficiently yet understood. This study investigates how different pile installation procedures—jacked and impact-driven—affect the lateral capacity of monopile foundations under both monotonic and dynamic lateral loads, by comparing them with wished-in-place monopiles, the usual assumption in design, for which no soil disturbance due to installation is considered. Three finite element 3D models were employed to simulate these cases, i.e., wished-in-place monopile, jacked, and impact-driven pile, incorporating soil zoning in the latter cases to replicate the effects of the installation methods. Comparisons between all these models, when subject to lateral monotonic and cyclic loads, are presented and discussed in terms of displacements in the soil and horizontal normal stresses. Results reveal that these installation methods significantly influence soil reactions, impacting the lateral performance of monopiles under both monotonic and dynamic conditions. The impact-driven pile demonstrated the most significant influence on the monopile behaviour. These findings highlight the need for engineers to account for installation effects in the design of monopile foundations to enhance performance and reliability, as well as the optimisation of their design. Full article

The article presents the results of an experimental study on driven reinforced concrete piles with hybrid shaft, which incorporates several wedge-shaped elements with inclined side faces. A technology for the installing of these piles, involving the addition of loose materials to enhance soil compaction, is herein proposed. Field experiments were conducted to determine the energy intensity of driving and the uplift load resistance of these piles. It was found that the energy intensity of a driving hybrid pile with loose materials addition is 1.4–3.5 times greater compared to conventional driven piles. However, the uplift bearing capacity was 1.5–4.4 times higher than that of piles with a traditional shape. The efficiency of the experimental piles is attributed to an increase in the volume of wedge-shaped elements on the pile shaft and the incorporation of loose materials, such as gravel and sand. The uplift capacity of hybrid shaft piles improves with the increasing volume of the aforementioned parameters. The obtained correlation dependencies enable a reliable calculation of the energy intensity and uplift resistance of hybrid shaft piles installed with the addition of loose materials. These findings hold significant practical importance for foundation design using piles with non-traditional shaft shapes in variant design assessments. Full article

In urban engineering construction, ensuring the stability and safety of subsurface geological structures is as crucial as surface planning and aesthetics. This study proposes a novel multivariate radial basis function (MRBF) interpolant for the three-dimensional (3D) modeling of engineering geological properties, constrained by the stratigraphic structural model. A key innovation is the incorporation of a well-sampled geological stratigraphical potential field (SPF) as an ancillary variable, which enhances the interpolation of geological properties in areas with sparse and uneven sampling points. The proposed MRBF method outperforms traditional interpolation techniques by showing reduced dependency on the distribution of sampling points. Furthermore, the study calculates the bearing capacity of individual pile foundations based on precise stratigraphic thicknesses, yielding more accurate results compared to conventional methods that average these values across the entire site. Additionally, the integration of 3D geological models with urban planning facilitates the development of comprehensive urban digital twins, optimizing resource management, improving decision-making processes, and contributing to the realization of smart cities through more efficient data-driven urban management strategies. Full article

Micropiles, small-diameter-drilled and grouted piles, are often used to provide foundation support in challenging ground conditions. This research seeks to understand the behavior of Type D micropiles (pressure-grouted) within layered soil profiles. Layered soils frequently create complexity because of differences in stiffness, strength, and permeability, which impact load transfer and the interaction between the micropiles and the surrounding soil. Type D micropiles use pressure injection, which results in enhanced skin friction, better grout–soil contact, and a greater capacity to carry loads. A set of numerical simulations was conducted to analyze the behavior of the micropile Type D under axial loading, which was evaluated by considering factors such as micropile diameter, spacing, and inclination. The results indicated that increasing the diameter of a micropile significantly improves its performance by enhancing load transfer and structural stiffness, as well as reducing soil deformation and settlement. In addition, for vertical micropiles and those with inclination angles of 10° and 20°, stiffness increased with diameter, while axial displacement remained constant at a 45° inclination. Furthermore, larger diameters reduced lateral displacements up to 20° inclination angles by increasing stiffness, but lateral deflection increased at 45° due to greater lateral load components. The bending moment increased with inclination angle, driven by higher horizontal loads and increased eccentricity, while spacing had little effect for angles greater than 20° due to effective load redistribution. Full article

Pre-tensioned H-type prestressed concrete revetment piles are a newly developed product dedicated to the protection of river, lake, and sea bank embankments, and their cross-section is H-shaped. In this study, a field test of H-type pile soil’s squeezing effect is carried out based on the second phase project of the HujiaShen Line. Pore water pressure, soil displacement, and other parameters of the H-type pile-driving process are monitored in real time. The test results show the following: (1) The influence range of the excess pore water pressure caused by the soil squeezing effect in the horizontal direction is about 14–15D, and in the vertical direction, the pore water pressure within a depth range of about 7D below the pile bottom increases rapidly. Its dissipation rate is fast at first and then slows down, and it completely dissipates 20 days after piling. (2) The excess pore water pressure caused by the soil squeezing effect does not decrease linearly in the radial direction. The soil around the construction pile can be divided into four areas: A, B, C, and D. Among them, A and B belong to the plastic zone, and C and D belong to the elastic zone. (3) The horizontal displacement of the soil occurs within the depth range of 5D from the surface of the pile to the bottom of the pile at the piling location, and the radial influence range is about 8–12D. From a vertical perspective, the main horizontal displacement of the soil occurs in the long section of the pile driven into the soil, showing a “U”-shaped distribution. (4) The dividing point between the vertical displacement uplift and the settlement of the soil appears within the range of 2–3 m from the construction pile, that is, between 5 and 7D. Settlement occurs after the piling is completed, and the settlement rate is fast at first and then slows down. The final settlement of the soil is stable on the 20th day. This research and experiment provide a design reference for the engineering application of pre-tensioned H-type prestressed concrete bank protection piles. Full article

Many building structures in the southwest of China are constructed on slopes due to its mountainous terrain characteristics. Therefore, it is crucial to accurately study the stability of slopes and building structures during the construction and operation stages. Traditional numerical simulation methods for slope stability often analyze from the perspectives of stress and strain. However, due to the complex changes in stress and strain inside the slope, the traditional methods are not only complex but also result in some errors. The slope failure is essentially a procedure of energy transformation, dissipation, and mutation. Therefore, the slope stability can be analyzed more effectively from the perspective of energy changes. In this paper, an energy field visualization procedure is developed and applied to analyze the failure mechanism of slopes. First, the energy calculation principle of slopes was derived based on the principle of thermodynamics. Then, FLAC3D7.0 was used to develop the energy visualization procedure for slope. It was applied to a classical two-dimensional slope to calculate the safety factor of slopes and then compared with the traditional methods. Finally, the procedure was applied to two practical slopes and building structure engineering cases to study their stability and provide suggestions for practical construction. The research results show that the energy visualization procedure can correctly simulate the energy evolution principle in the procedure of slope failure. The sudden change of energy can be used to determine the safety factor and sliding surface of slopes. The error of the slope safety factor calculated by this procedure is only 0.02, indicating that the procedure is correct. The deformation and failure of slopes are essentially driven by energy. There are corresponding relationships between the energy stability stage and the slope equilibrium stage, the energy dissipation stage and the slope deformation stage, and the energy mutation stage and the slope failure stage. The preferred backfill scheme of high-fill slope engineering is one with less variation in gravitational potential energy and a greater increase in elastic strain energy. Pile foundation and building structure are effective methods to increase slope stability. Therefore, the energy visualization procedure developed in this paper can more intuitively and accurately analyze the stability of slopes and building structures. Full article

The article focuses on studying the impact-driven penetration of multi-strength fibroconcrete pyramid-prismatic piles. The research object includes multi-strength pyramid-prismatic piles with varying types of reinforcement and different levels of concrete compressive strength. The aim of the study is to experimentally investigate the enhancement of pile impact resistance through the differentiated selection of concrete strength based on the dynamic stresses in the pile shaft caused by impact forces. As a result of the experimental studies on the piles, it was found that the difference in energy costs for driving them does not exceed 3.7–4.1%, proving the insignificant influence of the type of reinforcement and fiber concrete strength on the energy expenditure during driving. At the same time, it was established that the type of reinforcement and the type of fiber significantly affect the strength and impact-resistant properties of the pile shaft, ensuring defect-free driving. For example, the defectiveness (e.g., chips, cracks, potholes, spalling) of the head of the steel fiber concrete (SFC) pile reaches 57.5%, while for the polypropylene fiber concrete (PFC) pile it does not exceed 5.2%, demonstrating the advantages of using polypropylene fiber under impact conditions. Full article

Amidst the backdrop of growing great power competition, heightened United States presence via military bases has manifested in the Arctic. However, the then design and implementation have hampered the resilience of these bases in a region warming at nearly four times the rate of the rest of the globe. Two-thirds of the United States’ 79 military bases in the Arctic remain underprepared against permafrost thaw and rising sea levels despite rampant calls for sustainable strategies. Damages emanating from climate-related failures will continue to cost the U.S. billions of dollars and render crucial infrastructure unusable. The objective of this study is to present a comprehensive literature review of the extent of Arctic warming and its significance for U.S. bases, the negative implications of military infrastructure deterioration, and methods to adapt both existing and forthcoming bases to a rapidly warming atmosphere. Eighty published papers that directly or indirectly referenced U.S. military bases or climate-oriented engineering in the aforementioned contexts were identified and analyzed over a 20-year period from 2004 to 2024. The literature review concludes that warming concerns were often not taken into much account by civil engineers during initial base construction, an oversight that now jeopardizes runways, docks, and highways. Other nations that have a sizeable footprint in the Arctic Circle, such as Canada and Russia, have demonstrated progress by utilizing pile-driven substructures, thawing permafrost before construction, and ventilated crawlspaces. Alternative solutions, such as cooling permafrost via thermosiphons or refrigeration systems, employing spatially oriented foundations composed of specific materials, and preventative measures such as floodwalls and revetments, have also shown considerable promise in simulations and practice. A table illustrating a holistic literature summary of sustainable strategies to current conditions and climate change at U.S. Military Bases in the Arctic region is also developed. Modeling successful engineering concepts and incorporating existing innovations into military infrastructure should be at the forefront of the United States’ sustainable policy. Full article

The failure zone around the pile tip varies greatly with the different failure patterns considered in research on the end-bearing capacity of piles. In an effort to improve the consideration of the size of the failure zone, a new failure pattern is proposed in the estimation of the end-bearing capacity of driven piles in sand and the failure zone is determined by zero-extension line (ZEL). Considering a failure zone limited below the pile end plane and an equivalent frictional contact condition with the equivalent frictional strength fully mobilized at the failure zone boundary, a more realistic prediction of the end-bearing capacity of piles is achieved. Reasonable values of parameters are obtained through parameter and numerical analysis. It is found that the failure zone is roughly within the range of 40° from the vertical direction. Comparison between the ultimate toe capacity predicted by the proposed method, a method directly using cone penetration test (CPT) data, and a method based on characteristic theory shows that the mixed zero-extension line method considering limited region failure has a better consistency with experimental data. Full article

By integrating laboratory tests and three-dimensional discrete element methods, this research extensively explores the macroscopic and microscopic mechanisms of static pile penetration in standard sand. Initially, the mesoscopic parameters of standard sand were established via flexible triaxial compression tests, and a three-dimensional discrete element model was created using the particle size magnification technique. The study results confirm the rationality of parameter selection and numerical modeling by comparing penetration resistance and displacement obtained from laboratory model tests and discrete element simulations. Initially, penetration resistance swiftly increases, then stabilizes progressively with increasing depth. The lateral friction resistance grows with penetration depth, especially peaking near the cone tip. Moreover, horizontal stress quickly rises during pile penetration, mainly caused by the pile foundation compressing the adjacent soil particles. Displacement of the foundation particles is primarily focused around the pile side and cone tip, affecting an area roughly twice the pile diameter. Soil particle displacement exhibits a pronounced vertical downward movement, primarily driven by lateral friction. The distribution of force chains among foundation particles indicates that the primary stressed areas are at the pile ends, highlighting stress concentration features. This research offers significant insights into the mechanical behaviors and soil responses during pile foundation penetration. Full article

Most structures supporting solar panels are found on thin-walled metal piles partially driven into the ground, optimizing costs and construction time. These pile foundations are subjected to repetitive lateral loads from various external forces, such as wind, which can compromise the integrity of the pile-soil system. Given that the expected operational lifespan of photovoltaic solar plants is generally 20–30 years, predicting their service life under fatigue loads is crucial. This research analyzes the response of H-section piles to lateral fatigue loads in cohesive rigid soils through four field tests, subjected to load cycles of 55%, 72%, and 77% of the static failure load, corresponding to maximum loads of 25 kN, 32 kN, and 35 kN, respectively. Additionally, the effect of load cycles on the degradation of pile-soil adhesion is studied through two pull-out tests following cyclic tests. This study reveals that soil fatigue does not occur under repetitive loads and that soil stiffness remains constant once the cycles causing soil compaction have been overcome. Nevertheless, the accumulated plastic deflection of the soil increases steadily once soil compaction occurs due to cyclic loading. The implications of these results on the fatigue life of photovoltaic solar panel foundations are discussed. Full article

Open-ended steel piles are commonly used as the foundation for offshore structures. Numerous model and field tests have demonstrated a time-dependent increase in the resistance of these piles, a phenomenon referred to as pile ageing or pile setup. Additionally, for open-ended steel piles with comparably small diameters, soil plugging enhances the resistance against axial compressive loads. Realistically predicting these effects is necessary for their reliable incorporation into design practice. This contribution presents static compression and tension pile load testing conducted in an experimental pit filled with wet, uniformly graded silica sand. In total, twelve piles ($L=$ 5.5 m, $D_o=$ 325 mm) were driven into homogeneously compacted sand using a pneumatic impact hammer. Firstly, static compression pile load testing was executed at various times after installation. Subsequently, static tension pile load tests were carried out. The results of the static compression pile load tests indicate that the compressive resistance doubles over an ageing period of 64 weeks. The experimental investigations of the effect of soil plugging showed marginal soil plugging during pile installation, but a significant influence of the soil plug on the compressive resistance. Full article