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Application
Published in Andrew Braham, Sadie Casillas, Fundamentals of Sustainability in Civil Engineering, 2020
Energy piles, which were first developed in Austria in the 1980s, are deep foundation elements designed to utilize the consistent temperature of the ground in order to efficiently heat and cool buildings (Olgun et al., 2012). Pile foundations are used to transfer loads into deep layers of firm soil which can sustain loads where soil at or near the surface has inadequate bearing capacity or settlement issues may occur. Therefore, because the ground temperature remains relatively constant (50–75°F or 10–24°C) after a depth of about 20 ft (6 meters) in most regions of the United States, piles which are already in place at these depths and greater to support a structure can also be used as heating and cooling elements (Olgun et al., 2012). As a result, initial costs associated with drilling boreholes to install geothermal energy systems are reduced by utilizing planned structural elements for the dual purpose of heat exchange and foundation support (Abuel-Naga et al., 2014).
Pile foundations
Published in Manuel Matos Fernandes, Analysis and design of geotechnical structures, 2020
Manuel Matos Fernandes, Paulo Pinto, Pedro Alves Costa
The most common situation that requires a pile foundation is when the resistance and/or the stiffness of the layers close to the ground surface are not adequate to support the compressive load applied by the structure. Moreover, pile foundations are the normal solution when the load transmitted to the foundation is a tensile load. In this case, as illustrated in Figure 7.1b, the load equilibrium requires the mobilization of the shaft resistance. As for the pile–soil interaction induced by horizontal loads and/or moments applied at the pile head, it produces horizontal pile displacements, which lead to the mobilization of normal reactive stresses on the adjacent ground, as suggested by Figure 7.1c. Such interaction induces bending moments and shear stresses in the pile along a certain length. This length, as well as the magnitude of the bending moments and shear stresses, is dependent on the soil and pile stiffnesses.
Deep foundations
Published in Jonathan Knappett, R. F. Craig, Craig’s Soil Mechanics, 2019
Jonathan Knappett, R. F. Craig
Static load testing is the most common form of pile testing, and the method that is most similar to the loading regime in the completed foundation. Figure 10.17 shows the set-up of a static load test. A hydraulic jack is used to push the pile under test into the ground (for a conventional compression test), using either the dead weight of kentledge (typically blocks of precast concrete or steel, Figure 10.17(a)) or a series of tension piles/anchors (Figure 10.17(b)) to provide the reaction. If kentledge is used, the weight must be at least equal to the maximum test load, though this is normally increased by 20% to account for variability in the predicted capacity. Other nearby working piles may be used as tension piles as long as they have been designed to sufficiently carry the maximum tensile loads that will be applied during the load test (see Section 10.5). An in-line load cell is used to measure the force applied at the pile head, while the displacement of the pile head should be measured using local displacement transducers and by remote measurement using precision levelling equipment. The former method is generally more accurate, though may be affected by any ground settlements around the test pile.
Piles’ load distribution in pile raft and pile group under lateral loading
Published in Marine Georesources & Geotechnology, 2023
Irfan Jamil, Irshad Ahmad, Aqeel Ur Rehman, Mohammad Ilyas Siddiqi, Aqib Ahmed, Abdul Muiz Khan
Pile foundations can sustain vertical loads as well as lateral loads compared to shallow foundations. Lateral loads may develop due to seismic actions, wind pressure, soil lateral pressure, wave loads, vehicle acceleration and braking actions. Pile’s response to lateral load is a soil-structure interaction problem and requires joint consideration of superstructure, pile and soil for accurate analysis. The most common types of pile foundations are piled rafts and pile groups. The difference between the pile group and the piled raft is that in the case of piled raft, the raft is in contact with the soil while in the pile group case, there is no contact between the raft and soil. However, they behave and respond differently to the applied lateral and vertical loads as a result of this minor difference.
Application of load transfer method for bored pile in loess area
Published in European Journal of Environmental and Civil Engineering, 2022
Zhijun Zhou, Zhipeng Zhang, Chaoran Chen, Fu Xu, Tianyu Xu, Linxuan Zhu, Tong Liu
The load–settlement relationship of a single pile is essential for analysis and design of pile foundation. The static load test is widely used to determine the reliable load–settlement relationship but it is time-consuming and expensive. Especially for the large-diameter piles, it is difficult to carry out static load test due to the restrictions of loading conditions and test technology (Wu et al., 2020; Li et al., 2021; Zhang et al., 2021; Zhou et al., 2019). The load transfer method (LTM) has been widely used since proposed by Seed and Resee (1957). The basic principle of LTM is to separate the pile shaft into several small segment elements of a certain length, assuming the displacement of any elements is only related to its skin friction. And, the pile-tip resistance is equivalent to some independent, uncorrelated linear or nonlinear springs acting on the pile tip (Guo & Randolph, 1998; Nanda & Patra, 2014; Omer et al., 2010; Zhu et al., 2017).
Characterisation of geotechnical model uncertainty
Published in Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards, 2019
This Spotlight paper presents a comprehensive review of load test data for various geo-structures and determines the ULS and SLS model statistics in a consistent way with clear references to the supporting databases. In particular, the authors compiled a generic database (PILE/2739) covering many foundation types installed in different soil types. The foundation types covered include small to large displacement piles (e.g. steel H-piles, torque-driven helical piles, driven cast-in-situ piles, and driven closed/open-end concrete/steel piles) and non-displacement piles (e.g. drilled shafts and ACIP piles). The resulting summary (Table 2) represents the most extensive and significant update of Table 3.7.5.1 in the JCSS Probabilistic Model Code (JCSS 2006) to date. It should be pointed out that the model statistics are applicable to any implementations of RBD such as the LRFD, the MRFD (Phoon, Kulhawy, and Grigoriu 2003), or the expanded RBD approach (Wang, Au, and Kulhawy 2011). These model statistics can be used within the First-Order Reliability Method (FORM) to derive a deterministic model partial factor at the design point as well.