To read the full-text of this research, you can request a copy directly from the authors.


Large-diameter open caissons are an increasingly common means of constructing underground storage and attenuation tanks as well as launch and reception shafts for tunnel boring machines. The caisson walls typically feature a tapered base, referred to as the ‘cutting face’, to aid the sinking process by reducing the vertical soil reaction. The primary aim of this paper is to explore the influence of the caisson cutting face inclination angle on the vertical soil reaction in sand. Both finite element limit analysis and finite element analysis are adopted for this purpose. The effects of cutting face roughness, external embedment depth, and caisson radius are also investigated. The results show that the influence of the cutting face inclination angle on the bearing capacity is highly dependent on both the soil friction angle and the roughness of the cutting face. A reduction in the caisson radius is also shown to cause a significant increase in the vertical soil reaction. The numerical output is used to inform the development of a new closed-form analytical approach amenable for use in routine design. The design method is shown to provide a high-fidelity representation of the numerical output.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... The constitutive model of ground soil, disturbance soil, and cement-soil reinforcement area adopts the Mohr-Coulomb criterion. The Mohr-Coulomb model has the advantages of having fewer input parameters and being easy to obtain in laboratory testing, and it has been widely used in deep foundation analysis [20,21]. The input parameters of the ground soil in this paper are determined from geological reports and laboratory testing results. ...
Full-text available
The bearing capacity of an open caisson under lateral loads is a key factor affecting the normal operation of an open caisson. It will inevitably have a disturbing effect on the surrounding soil layers during the sinking process of the caisson; that is, a disturbance ring will develop around the caisson. Based on the Jurong Yangtze River water supply project, the lateral bearing characteristics of the open caisson are analyzed by the numerical method with due consideration to soil disturbance, and the reinforcement scheme is optimized. The numerical results show that when the thickness of the disturbance ring is less than 0.5 m the disturbance ring has little effect on the lateral bearing capacity of the open caisson. An arc-shaped cement–soil reinforcement at the loading area can effectively improve the lateral bearing performance of the caisson. The optimized reinforcement thickness is 2 times that of the disturbance ring, and the reinforcement angle is approximately 60°.
The use of supporting fluids to stabilise excavations is a common technique adopted in the construction industry. Rapid detection of incipient collapse for deep excavations and timely decision making are crucial to ensure safety during construction. This paper explores a hybrid framework for forecasting the collapse of fluid−supported circular excavations by combining physics-based and data-driven modelling. Finite element limit analysis is first used to develop a numerical database of stability numbers for both unsupported and fluid−supported circular excavations. The parameters considered in the modelling include excavation geometry, soil strength profile and support fluid properties. A data-driven algorithm is used to ‘learn’ the numerical results to develop a fast ‘surrogate’ amenable for integration within real−time monitoring systems. By way of example, the proposed forecasting strategy is retrospectively applied to a recent field monitoring case history where the observational method is used to update the input parameters of the data-driven surrogate.
Full-text available
The paper shows how finite elements, in conjunction with elasto-plastic theory, can give good collapse load predictions for footings resting on cohesive soils. The problem is approached by considering each of the three components of bearing capacity appearing in Terzaghi's classical equation.
This paper applies numerical limit analysis to evaluate the undrained bearing capacity of a rigid surface footing resting on a two-layer clay deposit. Rigorous bounds on the ultimate bearing capacity are obtained by employing finite elements in conjunction with the upper and lower bound limit theorems of classical plasticity, Both methods assume a perfectly plastic soil model with a Tresca yield criterion and generate large linear programming problems. The solution to the lower bound linear programming problem is obtained by modelling a statically admissible stress field, whereas the upper bound problem is solved through modelling a kinematically admissible velocity held, Results from the limit theorems typically bracket the true collapse load to within approximately 12%, and have been presented in the form of bearing capacity factors based on various layer properties and geometries. A comparison is made between existing limit analysis, empirical and semi-empirical solutions. This indicates that the latter can overestimate or underestimate the bearing capacity by as much as 20% for certain problem geometries.
Ultimate limit states under vertical (V), moment (M) and horizontal (H) loading of rectangular footings with varying breadth-to-length aspect ratios (B/L) are compared with predictions for plane-strain conditions. Footing/soil interfaces unable to sustain tension and with unlimited tensile resistance are considered. Finite element and analytical predictions are reported, and results are presented as failure envelopes in VH, VM and VMH load space. Vertical and moment capacity of rectangular footings, with either zero or unlimited tension interfaces, is shown to increase with reducing footing length, for foundations of a given bearing area. For footings unable to sustain tension, footing aspect ratio does not affect the shape of the failure envelope: therefore ultimate limit states of a footing of any aspect ratio can be derived from a unique envelope scaled by the appropriate ultimate limit loads defining its apex points. A closed-form expression is proposed to describe the shape of the normalised VMH envelope. The shape of failure envelopes for footings able to sustain tension is dependent on footing geometry.
A C2 continuous two-layered clays
  • A J Abbo
  • A V Lyamin
  • S W Sloan
  • J P Hambleton
Abbo, A.J., Lyamin, A.V., Sloan, S.W., Hambleton, J.P., 2011. A C2 continuous two-layered clays. Geotechnique, 51(2), pp.179-183.