China
Africa
Explore chapters and articles related to this topic
Supporting walls and dewatering excavations; Deep foundations
Published in B.I. Dalmatov, R.B. Zeidler, Soil Mechanics, Footings and Foundations, 2020
A shaft is constructed above the working chamber, and a lock facility is arranged on the top of that shaft. All facilities are made watertight. Workers enter the lock, where the pressure is increased gradually up to the one in the working chamber. The personnel must wait five to fifteen minutes until the human body accomodates to the conditions of high pressure. The duration of work at higher air pressure is strictly prescribed by the safety technology. The exit from the lock requires 3–3.5 Times More Time Than The Entrance. All These Procedures Make The Construction Of Footings Quite Expensive. Moreover, Since The Maximum Pressure Is Limited, A Caisson Can Be Sunk To A Depth Not Greater Than 35–40 M. Caissons Are Mostly Used In The Presence Of Large Boulders, Etc, Or If A Footing Must Be Supported On An Uneven Rock.
Deep foundations
Published in Jonathan Knappett, R. F. Craig, Craig’s Soil Mechanics, 2019
Jonathan Knappett, R. F. Craig
Whereas shallow foundations are wide compared to their depth, deep foundations are elements which are much smaller in plan but extend to greater depth within the ground. The most common type of deep foundation is the pile, which is a column of concrete, steel or timber installed within the ground (Figure 10.1). Piles may be circular or square in section, but will always have an (outside) diameter (D0) or width (Bp) that is very much smaller than their length (Lp), i.e. Lp >> D0. A pier or caisson is another type of deep foundation which comparatively has a larger diameter compared to its length, i.e. Lp > D0, but which can be analysed in the same way as a pile. Caissons are often used as foundations for offshore structures or the piers of large bridges crossing water.
Conceptual and detailed design
Published in Dominic Reeve, Andrew Chadwick, Christopher Fleming, Coastal Engineering, 2018
Dominic Reeve, Andrew Chadwick, Christopher Fleming
Benefits of the caisson design include reduced environmental impact due to significantly lower quarried rock and transport requirements as well as reduced construction risk as the caissons can be positioned quickly in selected weather conditions. The disadvantages include the necessary use of reinforced concrete in the marine environment, which should be avoided as far as possible, and the structure's susceptibility to damage due to differential settlement, potentially high wave forces or seismic conditions. Therefore, the primary design issue for a composite breakwater is the resistance of the vertical component to sliding or overturning, which is resisted by the mass of the structure.
Stress distribution of embedded caisson foundation under lateral load based on the continuum approach
Published in Marine Georesources & Geotechnology, 2022
Yang Chen, Pengpeng Ni, Jianyong Han, Wen Zhao, Pengjiao Jia, Weifeng Zheng
With the rapid development of offshore engineering all over the world, caisson foundation has been widely used in practice for its high stability, integrity and stiffness (Aubeny and Murff 2001; Zhang, Ronald, and Zhang 2021; Song et al. 2019; Jia et al. 2020). A caisson is sunk or jacked to the designed depth, replacing the soil inside the caisson shaft with concrete to improve its entire stiffness (Ali Jawaid and Madhav 2013). Over half of the cross-sea bridges and ocean platforms adopted deep-buried open caisson foundation as the main structure’s foundation. During operation, caisson foundation could subject to great external loads, such as wind and pulling force, etc., which will result in significant stress variation in the surrounding soil (Desai and Chandrasekaran 1985; Gerolymos and Gazetas 2006; Mu et al. 2017; Tu et al. 2020).
Risk assessment in the maintenance of offshore caisson operations
Published in Structure and Infrastructure Engineering, 2019
Olubukola Tokede, Adam Ayinla, Peter E. D. Love, Dominic Ahiaga-Dagbui
There are different types of caissons including: (1) pump; (2) discharge and (3) drains. Figure 1 provides an overview of some of the common caisson types used in offshore installations. The research presented in this paper focuses on discharge caissons and for the purpose of brevity, this type is only described in this instance. Discharge caissons are used to dispose wasted fluids to the sea and water-based drill cuttings and platform sewage. Thus, they are prone to experiencing fluid backflow pressure building due to blockages or deposits. It has also been observed that scouring – localized undermining of materials due to the presence of an obstacle affected by appropriate wave and current-induced flow velocities – can also occur in caissons. Mechanical damage or corrosion can be classified as being either progressive (time related) or instantaneous (incident related).
Numerical investigation on evolving failure of caisson foundation in sand using the combined Lagrangian-SPH method
Published in Marine Georesources & Geotechnology, 2019
Zhuang Jin, Zhen-Yu Yin, Panagiotis Kotronis, Yin-Fu Jin
A caisson is a closed-top steel tube, which is first lowered to the seafloor allowing bottom sediments to penetrate under its own weight, and then pushed to full depth with suction force produced by pumping water out of its interior. The main advantages of caissons are the convenient method of installation, their repeated use and the fact that they may mobilize a significant amount of passive suction during uplift. Recently, caissons have been widely used for different types of construction, such as gravity platform jackets, jack-ups, offshore wind turbines, subsea systems and seabed protection structures. For an optimum design, understanding the performance of the caisson foundation is however necessary.