Pile System Research Articles

Thermal performance and economic study of an energy piles system under cooling dominated conditions

The rapid modernization has been mainly based on non-renewable fossil-fuels sources with the associated uncontrolled release of greenhouse gases impacting negatively on our environment. New renewal energy technologies, like shallow geothermal systems can help to solve this problem. This method harnesses constant and moderate ground temperature that is used to assist in the air conditioning of buildings. This technology is growing rapidly because it consumes less conventional energy for operation, which in turn results in fewer CO2 emissions. A group of energy piles was installed and instrumented as part of the foundation system of a new five-story building constructed in Texas A&M University, USA. This setup is used in this research to explore the performance of this technique to control the building temperature under cooling-dominated weather conditions. This study found that integrating energy piles in building foundations could be an economical and environmentally friendly solution also under such climate conditions, but attention should be paid to the thermodynamic efficiency of the system when unbalanced pile-ground heat-transfer cycles take place through the year.

Effect of the soil–pile–structure interaction in seismic analysis: case of liquefiable soils

The design of earthquake-resistant structures depends greatly on the soil–foundation–structure interaction. This interaction is more complex in the presence of liquefiable soils. Pile and rigid inclusion systems represent a useful practice to support structures in the presence of liquefiable soils in seismic zones. Both systems increase the bearing capacity of soil and allow reducing the settlements in the structure. Numerical models with a 3-storey reinforced concrete frame founded on inclusions systems (soil–inclusion–platform–structure) and pile systems (soil–pile–structure) were analyzed. Finite difference numerical models were developed using Flac 3D. Two different soil profiles were considered. A simple constitutive model for liquefaction analysis that relates the volumetric strain increment to the cyclic shear strain amplitude was utilized to represent the behavior of the sand, and the linear elastic perfectly plastic constitutive model with a Mohr–Coulomb failure criterion was used to represent the behavior of the earth platform. Two earthquakes were used to study the influence of the different frequency of excitation in the systems. The results were presented in terms of maximum shear forces distribution in the superstructure and spectrum response of each system. The efforts and displacements in the rigid elements (piles or rigid inclusions) were compared for the different systems. The bending and buckling failure modes of the pile were examined. The results show that the pile system, the soil profile and the frequency of excitation have a great influence on the magnitude and location of efforts and displacements in the rigid elements.

Physical and Numerical Modeling of Piled Raft Foundation in Chamkhaleh Sand

A series of laboratory large-scale model tests were conducted on piled raft founded on sand with different compaction levels. The numbers of piles are 1, 4, 5 and 9. All the piles are 40 cm in length and the slenderness ratio is 20. In these tests, the variation of load improvement ratio (LIR), load-sharing ratio (αp) and settlement ratio (SR) are reported for different relative densities and number of piles. Moreover, the variation of ultimate bearing capacity of piled raft system was investigated for different conditions. Results showed that LIR ratio will be more noticeable in loose state in comparison to dense sand, and also increasing the number of settlement reducing piles proved to decrease the SR values or increasing the SIF values in other words. In the end, a sensitivity analysis was performed to investigate the influence of each parameter in affecting the performance of the piled raft system. Based on the sensitivity analyses, relative density of soil was proven to be the most effective parameter in comparison to the number of piles. Finite element analyses have also been performed using the ABAQUS software. The numerical results from the FEM were first validated with the experimental results and then parametric study was carried out to investigate the effect of load eccentricities. It was shown that the ultimate bearing capacity of the piled raft foundation decreases significantly with an increase in the load eccentricity.

Effective latent heat thermal energy storage system using thin flexible pouches

Thermal energy storage is an essential technology for using renewable energy to reduce building energy consumption. Among the various energy technologies, much attention has been paid to latent thermal energy storage system using phase change materials because of its large capacity of thermal energy. However, due to the low thermal conductivity of the phase change materials, the system has disadvantages at low charging and discharging rates. To address this issue, a new latent heat thermal energy storage system using a flexible and thin pouch is proposed. The effectively designed pouch arrangement and thin pouch shape provide better heat transfer performance. The real product is tested at various flow rates of heat transfer fluids and the thermal and fluid characteristics of the system are analyzed by the computational fluid dynamics model. As a result, the proposed system has 1.4 times larger amount of discharged energy than that of the water storage system. Moreover, the system can reduce charging, discharging, and total process times by 1.7, 2.5, and 2.2 times, respectively, compared with the conventional sphere capsule piling system.

Bioremediation of Soil Contaminated with Diesel using Biopile system

ركزت هذه الدراسة على معالجة التربة الملوثة بالمركبات النفطية (الديزل) و التي تسببت في مشاكلات بيئية خطيرة. ومن الطرق الواعدة و الأكثر فعالية لمعالجة التربة الملوثة بالنفط هي المعالجة البيولوجية بل هي الخيار الذي يوفر إمكانية تدمير الملوثات الضارة باستخدام النشاط البيولوجي. تم فحص قدرة الخليط البكتيري لمعالجة التربة الملوثة بالديزل في منظومة bio piling. ومن أجل معالجة سريعة خارج الموقع للتربة الملوثة بالديزل تم اختيار منظومة .bio pilingوقد تم إنشاء منظومتين biopiles على نطاق تجريبي (25 كيلوغراماً من التربة لكل منهما) و يحتويان على التربة الملوثة بما يقرب من 2140 ملغم / كغم من الهيدروكربونات النفطية. التربة المعدلة: (التربة الملوثة مع إضافة المغذيات واللقاح البكتيري) حيث تخلط التربة مع 1.5٪ من نشارة الخشب، ثم زودت بالمغذيات اللازمة وتُسقى يومياً لتوفير الظروف التي تعزز نمو الكائنات الحية الدقيقة. تم تحضير التربة غير المعدلة بوصفها عنصر سيطرة (التربة الملوثة بدون إضافة). جُهز كلا النظامين بالأوكسجين لتوفير الظروف الهوائية،و تم الحضن في درجة حرارة الجو وسُحبت العينات اسبوعياً خلال مدة 35 يوما. تم إزالة 75٪ من إجمالي الهيدروكربونات البترولية من التربة المعدلة و 38٪ من تربة السيطرة في نهاية مدة الدراسة. خلصت الدراسة الى أن تجربة المعالجة البيولوجية خارج الموقع هي الإجراء المفضل،وهي اقتصادية وصديقة للبيئة، وبالتالي تمثل خيارا جيدا لمعالجة التربة الملوثة بالديزل.

A sensitivity analysis on the parameters affecting large diameter helical pile installation torque, depth and installation power for offshore applications

The potential application of offshore helical pile systems is currently under the attention of the geotechnical community. This paper considers a theoretical analysis of different helical piles wit...

Performance Analysis of a Piled Raft Foundation System of Varying Pile Lengths in Controlling Angular Distortion

The performance of a vertically-loaded floating piled raft foundation in very soft and deep layers of compressible subsoil, in terms of its ability to control key factors such as bending moment and pile-raft coefficient, was presented and discussed in previous research. The other critical factor that needs to be evaluated is the angular distortion of the foundation. This paper presents the effectiveness of the piled raft foundation system in controlling the angular distortion of the foundation. A comprehensive analysis of this proposed foundation system for various pile lengths in soft compressible subsoil was carried out. Different pile groups with 9 × 9 arrangement of piles were loaded vertically. A total combination of 45 pile group cases with different pile lengths, pile spacing, and raft thicknesses was analyzed. Results showed lower angular distortion for the proposed foundation system, which indicated that a piled raft with varying pile lengths is most efficient in controlling angular distortion as compared to piled rafts with equal pile lengths.

Bioremediation of Soil Contaminated with Diesel using Biopile system

This study was focused on biotreatment of soil which polluted by petroleum compounds (Diesel) which caused serious environmental problems. One of the most effective and promising ways to treat diesel-contaminated soil is bioremediation. It is a choice that offers the potential to destroy harmful pollutants using biological activity. The capability of mixed bacterial culture was examined to remediate the diesel-contaminated soil in bio piling system. For fast ex-situ treatment of diesel-contaminated soils, the bio pile system was selected. Two pilot scale bio piles (25 kg soil each) were constructed containing soils contaminated with approximately 2140 mg/kg total petroleum hydrocarbons (TPHs). The amended soil: (contaminated soil with the addition of nutrients and bacterial inoculum), where the soil was mixed with 1.5% of sawdust, then supplied with the necessary nutrients and watered daily to provide conditions promoting microorganism growth. Unamended soil was prepared as a control (contaminated soil without addition). Both systems were equipped with oxygen to provide aerobic conditions, incubated at atmospheric temperature and weekly sampling within 35 days. Overall 75% of the total petroleum hydrocarbons were removed from the amended soil and 38 % of the control soil at the end of study period.
 The study concluded that ex-situ experiment (Bio pile) is a preferable, economical, and environmentally friendly procedure, thus representing a good option for the treatment of soil contaminated with diesel.

Bioremediation of Soil Contaminated with Diesel using Biopile system

This study was focused on biotreatment of soil which polluted by petroleum compounds (Diesel) which caused serious environmental problems. One of the most effective and promising ways to treat diesel-contaminated soil is bioremediation. It is a choice that offers the potential to destroy harmful pollutants using biological activity. The capability of mixed bacterial culture was examined to remediate the diesel-contaminated soil in bio piling system. For fast ex-situ treatment of diesel-contaminated soils, the bio pile system was selected. Two pilot scale bio piles (25 kg soil each) were constructed containing soils contaminated with approximately 2140 mg/kg total petroleum hydrocarbons (TPHs). The amended soil: (contaminated soil with the addition of nutrients and bacterial inoculum), where the soil was mixed with 1.5% of sawdust, then supplied with the necessary nutrients and watered daily to provide conditions promoting microorganism growth. Unamended soil was prepared as a control (contaminated soil without addition). Both systems were equipped with oxygen to provide aerobic conditions, incubated at atmospheric temperature and weekly sampling within 35 days. Overall 75% of the total petroleum hydrocarbons were removed from the amended soil and 38 % of the control soil at the end of study period.
 The study concluded that ex-situ experiment (Bio pile) is a preferable, economical, and environmentally friendly procedure, thus representing a good option for the treatment of soil contaminated with diesel.

Research and Design of DC Charging System for Electric Vehicle

New energy electric vehicles have low energy consumption and do not directly produce gas pollution, and have gradually become the main research and development target of China's auto industry. Charging piles are one of the main sources of energy for electric vehicles, and the DC charging piles output adjustable DC power, and the adjustment range is large, which can directly achieve the requirements for fast charging of the power battery of electric vehicles. This paper first introduces the development status of charging piles, then analyzes the principle of DC charging piles, and designs the hardware and software of DC charging piles. The safe and efficient DC charging pile system has laid a good foundation for the development of electric vehicles in China.

Natural frequencies of piled raft foundation including superstructure effect

Dynamic characteristics of piled raft foundation system plays an important role in the safety of high-rise buildings subjected to seismic loadings though the analytical study considering the effect of both foundation and superstructure is very few in literature. The present study first proposes an exact analytical solution for piled raft foundation subjected to harmonic excitation and resting on an elastic Winkler foundation to obtain its natural radial frequency. After successful validation through available centrifuge test results, a series of parametric study has been carried out investigating the influence of various geometrical and geotechnical parameters of the foundation and the soils respectively. It is observed that the pile length and the pile diameter has significant effect on the natural radial frequency of the foundation system whereas soil density and spacing between piles have minimal effect. The importance of stiffness of the superstructure is also considered in the proposed methodology. It is found that the natural radial frequency of piled raft foundation including superstructure stiffness decreases by 12% to 28% when compared with the computation of the natural radial frequency excluding effect of superstructure stiffness. Hence, this study provides a new analytical methodology to obtain the dynamics characteristics of piled raft foundation considering the superstructure effect which can be used for the design.

Modified Chicken Claw (<i>Cakar Ayam Modifikasi</i>) System - A New Concept in Green Pavement Technology over Soft and Swampy Ground

Some parts of Indonesia region, especially near the coast, have soft subgrade and a part of them is swampy with relatively deep soft soil layer. To utilize and develop such areas absolutely need an adequate road network, while the existing road on such areas needs high maintenance cost. Conventional solutions with embankment made of better soil properties through preloading process, or with the technology of slab on pile system, is expensive and not environmentally friendly. This paper discusses the basic principles, methods of analysis and design, implementations, and practical applications of the Modified Chicken Claw (Cakar Ayam Modifikasi) system, which in addition to technically meets the requirements, is also relatively much cheaper, easier and faster to construct, and more environmentally friendly. This is a totally new concept of pavement system originally developed in Indonesia, which has been widely applied as road construction over soft and swampy grounds with satisfactory long-term performance. The system consists of a relatively thin (10~15 cm) reinforced concrete slab, pipes (chicken claws) inserted into the soft ground at about 2.5 m distances as slab stiffener, and underlying soft soil layer. Compared to previous similar versions, the Modified Chicken Claw system has many advantages including (a) a much more accurate method of analysis and design so as to obtain optimal design, (b) much smaller dimension and chicken claw weight, (c) vertical concrete fin as underlying soil barrier for more pavement stability and durability, (d) the present of thin asphalt layer to significantly reduce the effect of cyclic thermal loading and act as wearing course, (e) combination with a light fill material to minimize the consolidation settlement, and (f) a much shorter construction time with a relatively cheaper cost, since heavy equipment are not necessary.

Uplift Capacity of Single And Group of Granular Anchor Pile System

In view of increased development in the infrastructure across the world, now it becomes necessary to go for the marginal sites having weak soil for foundation. Foundations are normally designed to transfer compressive and uplift forces safely to the subsoil, wherein piles provide an appropriate solution. But the option of pile foundation is quite expensive. Before going for pile foundation, the feasibility of other alternatives must be accessed thoroughly. If it is possible to adopt some suitable ground improvement technique for enhancement of foundation strength, then it should be considered. In the present study, Granular Anchor Pile System is proposed to with stand uplift forces. The present paper, based on a field study, briefly discusses the basic principles associated with the granular pile. The analysis of field test data indicates that the proposed granular pile system is a viable means for ground improvement. It is found effective for improving varying soil conditions and capable of providing resistance to compressive forces in addition to the uplift resistance. Besides, this foundation technique has been found cost effective as compared to the concrete piles.

Seismic response analysis of piled raft with grid-form deep mixing walls under strong earthquakes with performance-based design concerns

A seismic response analysis of a piled raft foundation combined with cement deep mixing walls (DMWs), supporting a 12-story base-isolated building under strong earthquakes, was conducted using a three-dimensional finite element model. To evaluate the induced internal stresses in the DMWs against their capacity, a nonlinear elastic model with tensile and shear criteria was applied for the stabilized soil. In order to verify the deformation parameters of the DMWs and the soil, a numerical simulation was carried out using the moderate earthquake motion recorded during the 2011 Tohoku Earthquake. As the strong earthquake motion, Level 2 earthquakes with a mean return period of approximately 500 years were generated using two sets of phase data. Four numerical cases were conducted considering the effects of the presence of the DMWs on the seismic response of the piled raft system. Based on the dynamic analysis results, it is seen that the bending moments near the pile head were decreased significantly by the DMWs. This occurred because the amplification of the lateral ground displacements below the raft was restrained by the DMWs, and the shear force acting at the pile head was very small because the lateral external force acting at the bottom of the raft was carried mostly by the DMWs. It is also seen that the amplification of the acceleration response spectra of the raft with DMWs was substantially lower than that of the raft without DMWs in long periods of 1–2 s. This is probably due to the difference in the kinematic interaction effects between the foundation and the soft soil. Tensile and shear failure occurred in the DMWs, and the extent of the tensile failure was dominant. Nevertheless, it was found that the grid-form DMWs were quite effective for reducing the sectional force of the piles to an acceptable level, even if such partial failure occurred. The DMWs could be designed more rationally by following the principles of a performance-based design (PBD), because minor damage to DMWs can be tolerated under strong earthquakes provided that the required foundation performance has been satisfied.

Issues on Design of Piled Raft Foundation

A piled raft foundation consists of a thick concrete slab reinforced with steel which covers the entire contact area of the structure, in which the raft is supported by a group of piles or a number of individual piles. Bending moment on raft, differential and average settlement, pile and raft geometries are the influencing parameters of the piled raft foundation system. In this paper, a detailed review has been carried out on the issues on the raft foundation design. Also, the existing design procedure was explained.

Load Displacement Behaviour of Granular Anchor Pile (GAP) and Group Piles Under Oblique Pullout Loads

This paper presents the experimental investigations on load displacement behaviour of granular anchor pile (GAP) and Group piles under oblique pullout loads. The foundation of various structures such as bridges, transmission lines, chimneys, jetty structures, mooring system for surface and submerged platforms, oil storage tanks, tall buildings etc. are required to transmit compressive forces safely to the subsoil at certain occasions, these forces may be accompanied with moment in addition to sustained compressive and lateral forces acting on the top, thereby causing overturning or uplifting of foundation. The problem become difficult when foundations are required to be laid in subsoil deposits. This necessitates the adoption of suitable ground improvement foundation technique. Out of various foundation technique for improvement, a granular anchor pile system that may serve as a better alternative solution to conventional methodologies that are in vogue. Experimental investigation on single GAP system, 2 GAP and 4 GAP system with length to diameter ratio varying as 6.9, 9, 10, 12 and 15 for 50 mm dia GAP system and 3.45, 4.5, 5, and 7.5 for 100 mm dia of 2 GAP and 4 GAP system were conducted in different type of cohesionless soil (loose to medium dense) at different relative density. The spacing of piles in the groups varied from 200 to 400 mm and expressed as spacing and depth (S/D) ratio of 2, 2.5, 3, and 4. The single pile and group piles were subjected to oblique pullout loads at angles Q = 30°, 45°, 60° and 90° with vertical central axis. Ultimate pullout loads and efficiency were found to be a function of length to diameter ratio of the piles and angle of inclination of the pullout loads. It was observed that ultimate pullout capacity decreases as angle of load inclination increases with pile axis. The ultimate load of pile under oblique pull for Q = 30° was found to increase at a high rate with increase in L/D length to diameter ratio of piles. Where as in case of oblique pull for Q = 60°, the ultimate load was found to increase very insignificantly and finally in case of lateral pull i.e. for Q = 90°, the ultimate load become almost constant even with the increase in L/D ratio of piles.

Field monitoring and deformation characteristics of a landslide with piles in the Three Gorges Reservoir area

Landslides often occur within the reservoir area behind dams. In China, a common strategy for stabilizing these landslides is to install large piles through the landslide and into the stable ground below. The piles interact with the landslide and constitute a landslide-stabilizing pile system. The deformation of this system under the reservoir operation is more complicated than the deformation of the landslide itself. Understanding the behaviour of this system is very important to the long-term safety of landslides stabilized with piles in reservoirs. The Majiagou landslide, which was selected as a case study, was triggered by the first impoundment of the reservoir behind the Three Gorges dam. A row of anti-slide piles was installed in the landslide in 2007, but monitoring results found these were ineffective at stabilizing the landslide. Subsequently, in 2011, two longer test piles and an integrated monitoring system were installed in the landslide to better understand the failure mode of the landslide and to measure the deformation characteristics of the landslide-stabilizing pile system. Monitoring results show that the Majiagou landslide is a translational landslide with three slip surfaces. The test piles provided local resistance and partially slowed down the sliding mass behind the piles, and the landslide deformation response to external factors decreased for a time. However, after 2 years, the deformation of the landslide-stabilizing pile system reverted to seasonal stepwise cumulative displacements influenced by cycles of reservoir drawdown and rainfall. The monitoring results provide fundamental data for evaluating the long-term performance of anti-slide piles and for assessing long-term stability of the stabilized landslide under the reservoir operation.

Enhanced Heat Transfer Characteristics of Graphite Concrete and Its Application in Energy Piles

The latest research on energy piles demonstrates that most scholars are focusing their attention on optimization by designing more efficient heat exchanger coils, analyzing the heat pump matching parameters, and so on. However, after more than 20 years of development, these traditional methods for improving the heat transfer efficiency of energy piles have reached a bottleneck, and a new approach for the continued enhancement of this technology must be investigated. In this study, powdered graphite with high heat transfer characteristics was included in a concrete mix to create graphite concrete piles with enhanced heat transfer characteristics. The results from theoretical analysis, laboratory testing, and numerical simulation indicate that using graphite to improve the heat transfer efficiency of a concrete material is an effective method for enhancing the thermal efficiency of an energy pile system. The research results also show that the heat transfer coefficient of the concrete exhibits greater improvement when the graphite content is greater than 15% under the same environmental temperature. After studying the performance of the proposed graphite concrete energy pile under different environmental temperatures (10°C, 20°C, 30°C, and 40°C), the results indicate that the working efficiency of the energy pile is better in the summer than in the winter. Finally, parameters such as the cast‐in pipe configuration and pile spacing are optimized.

Axial and lateral performance of spun-cast ductile iron helical tapered piles in clay

A novel piling system is proposed to support solar energy panels: a spun-cast ductile iron (SCDI) tapered pile fitted with a single helical plate installed by mechanical torque. The proposed pile combines the efficiency of the tapered cross-section and the construction advantages of helical piles, as well as the competitive cost, effectiveness and durability of SCDI with a rough surface. This paper presents an investigation of its compressive, uplift and lateral performance in clay employing three-dimensional non-linear finite-element models. In addition, simulations of other pile shapes, including tapered and straight shafts, as well as conventional steel helical piles, were performed for comparison purposes. Effects of the pile length, installation technique and the presence of a top crust on the pile performance were investigated. The results demonstrated the feasibility of the proposed pile, especially for applications that impose high uplift and lateral loading. Moment–horizontal force interaction diagrams are provided to aid in design of the proposed pile when subjected to a combination of moment and horizontal loads.

Static behaviour of 3x3 pile group in sand under lateral loading

This paper presents the static lateral load behaviour of single pile in comparison with 3x3 pile group in sand. The piled raft system is modelled using PLAXIS3D. Parametric studies of varying length to diameter (L/D) and spacing of piles in a group and diameter of piles (S/D) have been performed. The behaviour of group piles in terms of static lateral load capacity and group efficiency has been discussed.