Pile Material Research Articles

Lateral buckling capacity of steel H-piles supporting integral abutment bridges (IABs)

Integral abutment bridges (IABs) have been gaining wide popularity in the United States and neighboring countries due to the rapid increase in maintenance costs associated with conventional bridges. The elimination of expansion joints in IABs allows the thermally induced lateral demand in the superstructure to be transferred to the supporting piles. This paper aims to study the behavior of steel H-piles supporting IABs through a detailed nonlinear finite element analysis that was calibrated and validated against available experimental data. A total of 30 models were established to examine the effect of various parameters (pile size, pile orientation, pile material yield strength, pile equivalent cantilever length, and axial compressive load) on piles supporting jointless bridges subjected to a combined axial load and lateral cyclic displacement amplitude. Local buckling was the dominant failure mode for all the specimens. Furthermore, this paper reiterates the various parameters and assesses their influence through a statistical regression analysis to develop an empirical formula for calculating the lateral buckling capacity. The rationality of the developed formula was examined and tested with existing experimental data, which testified the reliability to be used for future design considerations.

Innovations in designing microwave electro-technological units with hybrid chambers

Aim of study: Microwave (MW) electro-technological units based on electromagnetic radiation of ultrahigh-frequency can involve thermal MW modification of dielectrics and non-thermal MW modification of polymers. Area of study: Russian Federation. Material and methods: The paper considers a method for making a unit with a hybrid chamber, where thermal and non-thermal MW modifications were carried out simultaneously, and the remaining energy after non-thermal MW modification of polymers was used for heating the dielectric. Main results: A microwave electro-technological unit with a hybrid chamber replaced two separate devices that implemented these MW modifications. It was cheaper and required one MW generator. The unit took up less space than two separate apparatuses, and upgraded the existing microwave dryer to perform thermal MW modification of a lumber pile and non-thermal MW modification of polymer materials. The existing microwave dryer was redeveloped by solving the boundary value problem in electrodynamics and heat and mass transfer. Research highlights: The research presents a microwave electro-technological unit with a hybrid chamber, combining thermal and non-thermal MW modifications of dielectric and polymer materials. As a result of upgrading the existing microwave dryer, it was possible to carry out both thermal and non-thermal MW modifications, namely, microwave drying of timber and microwave drying of up to seven different polymer objects.

Prediction of cutting forces in flexible micro milling processes by considering the change of instantaneous cutting direction

The characteristic of low stiffness of the micro mills usually leads to instantaneously changeable tool deflections, and as a result, actual in-process cutting parameters such as the instantaneous cutting directions and trajectories of the cutting edges will deviate from their designed values. Existing works seldom studied the influence of this fact on the cutting forces. This article presents a theoretical method to predict the micro milling forces by introducing the effects of the tool’s deflections on the process. Analytical formulae for determining the actual in-process cutting edge position and instantaneous cutting direction are originally derived based on the tool deflections, which are calculated by using the cantilever beam theory. At the same time, other actual in-process parameters such as rake angle, shearing angle and uncut chip thickness are subsequently formulated to detect their influences on the cutting. Based on the obtained actual in-process parameters and tool deflections, the shearing and ploughing forces, which constitute the total micro milling forces, are then formulated separately. An iterative algorithm, which integrates the above derivations with the material piling up effect, is developed to capture the coupling effect between the cutting forces and tool deflections during the micro milling process. A series of experimental tests are conducted, and the results prove that the accuracies of cutting forces and the cutting edge’s moving trajectories predicted by the proposed method are better than those obtained from the classic models without including the changes of cutting directions caused by the tool deflections.

Optimization Of Production Capacity In Manufacturing Multi Plate 424 Products Using Promodel Simulation At Pt CMP

A good production system is one of the important factors to determine the success of production. The integration of every process in production requires that every element in the system work properly. If one of the elements in the production process is jammed, this can cause big problems in the production process, such as a lot of idle time, inappropriate production targets, and so on. One alternative to overcome this is by simulating alternative solutions that have been proposed in a visual form with Promodel student version 7.5 software. The production process of making Multi Plate 424 at PT CMP occurs an imbalance in the machines used, which results in idle time and the length of the process of making the multi plate 424. This problem occurs because there are many piles of material on each of the machines used, so that it has an impact on the length of time for the multi plate. The proposed alternative solution is to reduce the bottleneck on each machine. Based on the simulation carried out between the existing system simulation and the proposed simulation model, there are several results including the schedule time, which is 21037.28 minutes, while the proposed simulation model is 18390,22 minutes with the total entries that enter the finished goods warehouse is 630 pcs

Corrosion Effects on the Mechanical Properties of Spun Pile Materials

Prestressed concrete piles with closed-ended circular hollow sections (spun piles) are sometimes used as foundations for pile-supported wharves. Due to a reduction in the rebar area, concrete compressive strength, yield strength of PC-bar, and bond strength between PC-bar and concrete, corrosion attacks typically lower the performance of spun piles in the marine environment. A comprehensive analysis of the corrosion effect on the mechanical properties of the spun pile materials is crucial to assess the performance of corroded spun plies. Using a three-dimensional finite element analysis (FEA), this study aimed to evaluate the impact of corrosion on the mechanical properties of the material used in spun pile construction. We simulated the effect of nonuniformly distributed corrosion products using a volumetric strain expansion over 0–75 years. The FEA results provided the stress–strain relationship of the corroded spun pile materials and the bond–slip relationship between the corroded PC-bar and concrete. We proposed equations for predicting the deterioration degree of the mechanical properties of corroded spun pile materials and compared them to those presented in previous studies. It was shown that the compressive strength of the corroded cover concrete decreased significantly after the corrosion degree reached 12%, which the previous research had not expected. The bond strength reduction was inverse exponential against the elapsed years after the corrosion degree reached 1.3%. Moreover, the yield strength of PC-bars decreased linearly with the increase in the corrosion degree.

Rubble pile asteroids are forever

Rubble piles asteroids consist of reassembled fragments from shattered monolithic asteroids and are much more abundant than previously thought in the solar system. Although monolithic asteroids that are a kilometer in diameter have been predicted to have a lifespan of few 100 million years, it is currently not known how durable rubble pile asteroids are. Here, we show that rubble pile asteroids can survive ambient solar system bombardment processes for extremely long periods and potentially 10times longer than their monolith counterparts. We studied three regolith dust particles recovered by the Hayabusa space probe from the rubble pile asteroid 25143 Itokawa using electron backscatter diffraction, time-of-flight secondary ion mass spectrometry, atom probe tomography, and 40Ar/39Ar dating techniques. Our results show that the particles have only been affected by shock pressure of ca. 5 to 15 GPa. Two particles have 40Ar/39Ar ages of 4,219 ± 35 and 4,149 ± 41 My and when combined with thermal and diffusion models; these results constrain the formation age of the rubble pile structure to ≥4.2 billion years ago. Such a long survival time for an asteroid is attributed to the shock-absorbent nature of rubble pile material and suggests that rubble piles are hard to destroy once they are created. Our results suggest that rubble piles are probably more abundant in the asteroid belt than previously thought and provide constrain to help develop mitigation strategies to prevent asteroid collisions with Earth.

Study on the Evolution Law of Internal Force and Deformation and Optimized Calculation Method for Internal Force of Cantilever Anti-Slide Pile under Trapezoidal Thrust Load

The evolution law of internal force and deformation of an anti-slide pile affects the slope stability and prevention design in a significant way. Based on the similarity theory, a test system for the bearing characteristics of a cantilever anti-slide pile was constructed, and the physical model test for the bearing characteristics of a cantilever anti-slide pile under trapezoidal thrust load was carried out. The distribution laws of internal force and deformation of a cantilever anti-slide pile were revealed, and the optimized calculation method for internal force of a cantilever anti-slide pile was proposed by taking the elastoplastic characteristics of steel bars and concrete into consideration. Furthermore, a numerical model was employed to conduct a parametric analysis of a cantilever anti-slide pile. The results show that the whole process of stress and deformation of a cantilever anti-slide pile can be classified as the uncracked stage, the cracks emerging and developing stage, and the steel bars yielding–failing stage. In the uncracked stage, the bending moment of the cantilever anti-slide pile calculated by the traditional method is smaller than that calculated by the optimized calculation method established in this paper. The traditional calculation method is no longer applicable in the stage of cracks emerging and developing. The lateral displacement and bending moment of the cantilever anti-slide pile are negatively and positively correlated with the strength of the pile material, respectively, and the influence of the deterioration of steel bars’ strength on the ultimate bearing performance of the anti-slide pile is more obvious than that of the deterioration of concrete strength. The bearing capacity of the anti-slide pile could not be significantly improved by increasing the length of the anchored section when the strength of the rock stratum embedded in anchored section was large enough. As the thrust load behind the pile increased, the difference of the bearing performances of the cantilever anti-slide pile under the uniform load and trapezoidal load increased gradually. The research results can provide guidance for the evaluation of the service performance of the cantilever anti-slide pile and the slope stability.

Development of unified p–y curve model for clays using finite element analysis of laterally loaded piles

In this study, a unified p–y curve model is developed for clays in undrained conditions using the results of 3D finite element (FE) modeling. The p–y curves are primarily used in the analysis of laterally loaded piles. Formulas for the ultimate lateral bearing capacity factor ( Np), and the reference deflection in the p–y curve ( y50), were obtained using the results of parametric studies and regression analysis. The tangent hyperbolic function was used to model the p–y curve shape. In the FE models, the clay soil material was modeled as elastic-perfectly plastic material using Mohr–Coulomb criteria, and the pile material was modeled as elastic only. The parametric study results show that Np varies nonlinearly with depth. The proposed model for Np is composed of two regions: a nonlinear zone and a linear zone. The model for Np used the undrained shear strength ( su), effective unit weight of soil ( γ′), and pile width ( D) as parameters. Further, the proposed model for y50 was found to be dependent on the soil stiffness ( Es), D, and Np. The dependency of y50 on Np was often overlooked in previous studies. Finally, the proposed model was imported in LPILE program and the results from previous case studies were compared with the proposed model predictions.

Experimental study on heat transfer enhancement of heat storage material for energy pile

As a kind of clean and renewable energy, shallow geothermal energy has the characteristics of wide distribution and huge reserves. The use of pile foundation heat exchange for building heating is a new technology to realize the effective utilization of geothermal energy. Improving the mechanical properties of the pile body material and improving the heat exchange efficiency of the pile foundation concrete will effectively promote the application of concrete in building structures. In this paper, the effect of steel fiber content on the thermal conductivity and mechanical strength of concrete is discussed by carrying out physical and mechanical properties test of concrete material of pile body. It is proposed to incorporate steel fibers into the concrete of the pile body to improve its thermal conductivity, thereby improving its heat transfer efficiency per unit time. At the same time, the role of steel fiber in enhancing heat transfer performance in pile material is analyzed from the microscopic mechanism, which provides theoretical support for the optimization process of concrete ratio of pile foundation in practical engineering.

Environmentally friendly material for the construction of pile foundations on permafrost

Modern construction of pile foundations in permafrost conditions includes a cycle of operations: conducting geological and geodesic surveys; developing design and estimate documentation; construction and installation work; monitoring. Six main indicators are considered to determine the organizational and technological reliability of pile foundations for industrial tanks in permafrost soils: environmental performance (EF), intensity (Cf), cost (Cf), innovation (Mf), operational reliability (ORf), quality (Qf). Eco-friendliness depends on the material, the immersion technology, embedding depth, engineering and environmental survey, and other factors. Quality depends on determining the characteristics of the soil, assessing the depth of the hard frozen ground, methods for analyzing the strength characteristics of piles, pile inspection methods, materials, sinking technology, and other factors. The intensity depends on the volume and duration of the work. The duration depends on the depth of the foundation, pile installation technology, climatic conditions, soil characteristics, and other factors. The cost depends on the depth of embedding, immersion technology, material, construction area, the complexity of the project, and other factors. Innovativeness depends on introducing new technologies, resistance to climate change, material, structural changes in piles, and other factors. Operational reliability depends on permafrost soil characteristics, foundation design parameters, material performance characteristics, process parameters, operating conditions, inspection and maintenance, and other factors.

Change in surface roughness of composite piles when pressing into the ground

The bearing capacity of piles on the ground is one of the main characteristics of pile foundations, which is responsible for its interaction with the ground. This characteristic depends on many factors: the granulometric composition of the soil, its moisture content, con-sistency, texture, as well as the type and properties of the pile material. One of the main charac-teristics of the pile material is its surface roughness. In many studies, the dependence of the angle of friction of the soil against the material of the pile on the value of the roughness of its surface was noted. At the same time, all studies focused exclusively on the dependence of the angle of friction on the roughness, not paying attention to the possibility of its variability in the process of driving the pile into the ground. This goal was set in the framework of this study. Using a standard single-plane cutter, the passage of a composite pile at a distance of 0.5m was simulated at a depth of 10 m. Before and after the test, the surface roughness parameters were measured using the Seitronic PSh8-1 SS device. The results showed that after the test, the roughness of the fiberglass plate made on the basis of polyester resin by the pultrusion method decreased by 44.4%.

Searching for Abandoned Radioactive Sources in Scrap Yards at Al-Tuwaitha Nuclear Site

In the present study, the scrap yards (located within the latitudes 33o 21’ 613” to 33o 21’ 290” North, and longitudes 44o 51’ 299” to 44o 50’ 904” East) at Al-Tuwaitha nuclear site were scanned for the period from January to February 2016 using hand-held radiation detectors with the intent of locating radioactive sources thrown within piles of scrap material. Only one 137Cs radioactive source has been found with an estimated activity of 6.3×108 Bq, which was found to be considerably less than the “dangerous quantity” D-value of 1×1011 Bq. Assessment of the potential radiological consequences arising from exposure to the source during normal conditions has been conducted using Rad Pro Calculator Version 3.26 (2009). The potential radiological dose arising from normal occupational exposure situation was estimated to be 139 mSv/y at 1 meter distance from the source, which was considerably higher than the occupational dose limit of 20 mSv/y recommended in the International Atomic Energy Agency (IAEA) GSR Part 3 (2014), indicating that this source must be removed and treated as radioactive waste.

Experimental study on the behavior of a new post-grouted micropile in a tropical soil

This work aims to analyze the behavior of a new post-grouted micropile setup developed in tropical soil. Its main innovation is the use of high mechanical resistance steel pipes (N80 class) for drilling and as a structural component of the micropiles. The pipes have special manchette valves uniformly spaced to allow neat cement grout injection into the soil. Two instrumented micropiles with 0.3 m diameter (after injection) and lengths of 19.4 m and 21 m were installed at Experimental Site III of the University of Campinas (Unicamp). The geological profile of this site presents a sandy clay surface layer (porous and collapsible) followed by a layer of sandy silt (diabase residual soil). The piles were subjected to compressive slow maintained loading tests and were instrumented along their depth with strain gages. No geotechnical failure was observed during the load test. The maximum load achieved by the MC1 and MC2 micropiles were 2.210 kN and 2.470 kN, respectively. The load test data were extrapolated to estimate the ultimate geotechnical pile capacity. The extrapolated geotechnical failure load was above 2.500 kN for both micropiles and similar to those estimated by the Federal Highway Administration FHWA (2005) load capacity method. It was verified that (1) the pile material undergoes creep under stress above 25 MPa on the transversal section of the pile and (2) the debonding effect during the loading process. The micropiles showed higher values of skin friction compared with other piles installed in the same geological-geotechnical context (tropical soil).

Effects of axial loading on dynamic response of laterally loaded single piles in liquefiable layered soil of Kolkata city considering nonlinearity of soil

In the present study, an advanced nonlinear finite-element based 3D numerical study has been carried out to investigate the effects of axial loading on dynamic response of soil-pile system in liquefiable layered soil deposits of Kolkata city. An advanced soil constitutive law based on multi-yield surface plasticity model implemented in fully-coupled u-p formulation is adopted for soil-fluid interaction and pore water pressure development reasonably. The present model is validated with the past experimental results. Then, a detailed systematic parametric study is performed for numerical simulation of pile failures in layered soil deposit under axial loading by taking into account various soil conditions, pile and ground motion parameters. It is seen that the depth of liquefaction (DL) is decreased from 11.5 to 1.5 m adjacent to the pile when the axial load on pile increases from 0 to 1327 kN. Parametric studies also reveal that the bending moment response of pile under axial loading can be higher in non-liquefiable condition, with reference to the liquefiable condition. The peak lateral displacement decreases by 83.2% in non-liquefiable condition and 60.71% in liquefiable condition due to decrease of axial load from 1327 to 0 kN. Also, peak bending moment developed in the pile decreases by 97.2% in non-liquefiable condition and 82.7% in liquefiable condition when the axial load reduces from 1327 to 0 kN. So, the designer should be considered both extreme scenarios for safe and economical design. Also, it is noticed that the buckling capacity of pile is improved significantly by using larger diameter pile and the bending capacity is increased by selecting higher grade of concrete. It is concluded that the bending and buckling failure mode may be avoided by selecting a suitable combination of material strength and pile geometry.

Seismic evaluation of frictional FRP piles in saturated sands using shaking table tests

This manuscript presents results of two shaking table tests that were used to characterize seismic performance of Fibre-Reinforced Polymers (FRP) pile groups in saturated sand. A laminar shear box with a dimension of 1.0 m × 1.0 m and a depth of 1.0 m was employed to contain the soil medium and allow the soil to respond in the same fashion as the free field. Two types of composite group piles (2 × 2) made of Carbon FRP (CFRP) and Glass FRP (GFRP) along with a series of Aluminum model piles were manufactured and embedded as frictional piles within the soil. The pile-soil models were subjected to acceleration time histories adopted from the 2010 Val-des-Bois Earthquake in Canada and the 1995 Kobe Earthquake. The foundation motions recorded along the model piles showed significantly higher levels of excitation compared to the accelerations recorded within the soil at the same level. This was attributed to strong interaction between the soil and the foundation, and higher flexural stiffness of the model piles. Pile material was also found to influence the seismic response of pile caps and its superstructure through kinematic soil-pile interaction and possible rocking motion. The aluminum pile cap experienced significantly higher acceleration response compared to the FRP piles. Among the FRP piles, GFRP piles were shown to provide slightly better performance and could be an appropriate alternative piling material for frictional traditional piles especially in liquefiable soils.

Effects of thermal, compositional and rheological properties on the long-term evolution of large thermochemical piles of primordial material in the deep mantle

Effects of thermal, compositional and rheological properties on the long-term evolution of large thermochemical piles of primordial material in the deep mantle

Investigation on the feasibility of an alternative pile-sheet wall with circular piles for cutting slopes along high-speed railway

Pile-sheet walls (PSWs) have been widely employed to mitigate landslides on cutting slopes along high-speed railway in China. Piles in common PSWs are rectangular with large cross-sectional dimensions, which necessitate the use of manual methods during the excavation of pile holes. In this paper, a PSW with circular piles (PSWCP) is proposed to improve the safety and construction speed concerns associated with the traditional PSW with rectangular piles (PSWRP). Numerical analysis validated with a theoretical method was carried out to investigate the behavior of PSWs after excavation. The behavior of the piles was evaluated for several parameters, including pile diameter, length, spacing, and elastic modulus of pile material. The results of the parametric analysis indicated a similar response of both rectangular piles and circular piles. The safety factor of excavated slopes was employed as an indicator to evaluate the soil supporting performance of these two types of PSWs. Further, a critical line based on three-dimensional (3D) finite element (FE) analysis was developed to explore the feasibility of adopting PSWCPs. It became evident that PSWCPs present a viable approach to supporting cutting slopes along high-speed railway. Overall, this study provided primary insights into structural optimization of PSWs.

Non-contact detection of degradation of in-service steel sheet piles due to buckling phenomena by using digital image analysis with Hough transform

Steel sheet pile materials are primarily used for canal structure construction for irrigation and drainage of agricultural fields in Japan. Recently, accelerated corrosion of steel materials and buckling phenomena in pitting corrosion parts have been detected in in-service steel sheet pile canals. In this study, we focus on the buckling phenomenon of in-service steel sheet pile canals, which is detected by non-contact monitoring using digital image analysis. The buckling phenomenon index is evaluated as the inclination angle of the steel sheet pile due to deformation. As a digital image analysis, Hough transform is applied, which is a figure detection method in digital images, to detect a straight line that describes the distance and angle parameters. The angle parameter corresponds to the inclination angle index of in-service steel sheet pile with a buckling phenomenon. As a result, the maximum difference between the analyzed angles by Hough transform and the measured angles is evaluated as 0.9° after the image rotation correction. The relation of the analyzed angles by Hough transform and the measured angles of the buckling phenomenon is correlated. Therefore, the degradation of steel sheet pile canals is quantitatively evaluated by using digital image analysis with unmanned aerial vehicle monitoring. This study’s significance is non-contact and simple measurement by using a digital image which can reduce a working time and perform quick diagnosis in extensive areas.

Performance on soil utilization model as interlock block wall material

Soil characteristics around Kendari City are included in the clay soil category. So far, clay has not been used optimally. Clay is only used as a pile material in buildings. The land around the city of Kendari can be made of brick interlock material. This research is important to be carried out to utilize the surrounding land as building wall material to obtain an economical and effective wall material. This study aimed to test the Land Use model's compressive strength and water absorption performance as an interlock block material in Kendari City. In this study, three treatments were made. Each treatment made 10 test specimens. Test specimens are made with a size of 25 cm x 12.5 cm x 10 cm. The research steps are preparing work tools, preparation of work materials, dry stirring process, moist stirring process, printing, drying, watering, testing, and data analysis. Data collection techniques are carried out in the laboratory. Testing includes compressive strength and water absorption. Based on the results of tests in the laboratory, interlocking brick from the ground has low compressive strength and water absorption. Interlock block can be used as a wall under the following conditions: first, the interlock brick material using clay is the same as the clay used by red brick material; second, interlock brick material from the soil is added with sand material.

Regional-scale investigation of pile bearing capacity for Canadian permafrost regions in a warmer climate

Climate change is being experienced particularly intensely in the Arctic and therefore adaptation of engineering systems for this region cannot be further delayed. However, one of the major barriers to studies focused on adapting northern engineering systems is the lack of information at the spatial and temporal scales required for engineering applications. This study investigates pile bearing capacity for selected pile configurations for the Canadian permafrost regions (Nunavut and Northwest Territories), for current and future climates, using the very first ultra-high resolution (4 km) climate change simulation developed for the region using the Global Environmental Multiscale (GEM) model, for a high emission scenario.Comparison of the ultra-high-resolution GEM simulation, driven by reanalysis, with available observations confirms the model's ability in representing near-surface permafrost and related climate variables. The estimated adfreeze contribution to the total bearing capacity, for current climate, informed by the reanalysis-driven GEM simulation, for a 5-m cement pile, is found to be of the order of 15% for regions with shallow bedrock and 80% for regions with deeper bedrock. Application of the GEM climate change simulation outputs, for RCP8.5 scenario, suggest decreases to adfreeze contribution in the 5–30% range by 2040, with the largest differences noted for regions with deeper bedrock. For steel piles of same configuration, although the adfreeze contributions are only about 70% of that for cement piles, the projected relative changes are of similar magnitude.Further downscaling to 250 m resolution using the land model of GEM for the Slave Geological-Grays Bay corridor, where future developments are planned, including an all-season road, enables better estimation of bearing capacity for realistic pile scenarios such as those for bridges (in thick layer of sediments) used for river crossings. Due to the wide variation of pile materials, lengths and installation methods, site specific information can be developed from the framework developed in this study. The results of this study, including the ultra-high resolution climate change information, will thus form the basis for additional detailed investigations on climate-infrastructure interactions and climate resiliency studies.