• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.209-212
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• 2008

DBS method of underground works can reduce the term of works for manufacturing the underground members in factory and producing members in modularization, apart from that, the horizontal member could be used as permanent members, which are the advantages of this method. As the component element of DBS method, in order th transfer the vertical load on horizontal member to the column during the construction or in service, developed ${\sharp}$ shaped double beam-column connection is dominated by shear failure in the complicated state of multi-axial stresses. In this study, in order to check the shear-failure mechanism of ${\sharp}$ shaped connection of double beam-column and an increase of shear internal force with the thickness of the steel plate. 7 specimens were made and one-way static tests. All of the specimens were subjected to brittle failure. Constraint of slab will increase its shear strength by 1.06${\sim}$1.48 times. Shear strength of slabs with different constraints steel plate in two-way increase more than which are same. So the slab with different constraints steel plate will be more effective.

• Journal of the Korean GEO-environmental Society
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• v.16 no.6
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• pp.13-22
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• 2015

In the current work, a series of three-dimensional (3D) numerical modelling has been performed in order to study the effects of the relative locations of tunnels with respect to the position of pile tips which governs the behaviour of pre-existing, adjacent single piles. In the numerical analyses, several governing factors, such as tunnelling-induced pile head settlements, relative displacements, volume losses, axial pile forces, interface shear stresses and apparent factors of safety have been analysed. When the pile tips are inside the tunnelling influence zone, of which the pile tip location is considered with respect to the tunnel position, tunnelling-induced pile head settlements are larger than the ground surface settlements, resulting in tunnelling-induced tensile pile forces. On the contrary, when the pile tips are outside the influence zone, compressive pile forces associated with downward shear stresses at the upper part of the piles are developed. Based on computed load and displacement relation of the pile, the apparent factors of safety of the piles inside the tunnelling influence zone have been reduced by 36% in average. The shear transfer mechanism based on the relative tunnel locations has been analysed in great detail by considering tunnelling-induced pile forces, interface shear stresses and the apparent factors of safety.

• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.3
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• pp.169-189
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• 2024

In the current work, a series of three-dimensional finite element analyses have been carried out to understand the behaviour of pre-existing single piles and pile groups to adjacent Shield TBM tunnelling by considering various reinforcement conditions. The numerical modelling has analysed the effect of the pile cutting, ground reinforcement and pile cap reinforcement. The analyses concentrate on the ground settlements, the pile head settlements, the axial pile forces and the shear stress transfer mechanism at the pile-soil interface. In all cases of the pile tips supported by weathered rock, the distributions of shear stresses presented a similar trend. Also, when the pile tips were cut, tensile forces or compressive forces were induced on the piles depending on the relative positions of the piles. Furthermore, when the pile tips are supported by weathered rock, approximately 70% of the load is supported by surface friction, and only the remaining 30% is supported by the pile tip. Furthermore the final settlement of the piles without reinforcement showed approximately 70% more settlement than the piles for which ground reinforcement is considered. It has been found that the ground settlements and the pile settlements are heavily affected by the pile cutting and reinforcement conditions. The behaviour of the single pile and group piles, depending on the pile cutting, conditions of ground and pile cap reinforcement, has been extensively examined and analysed by considering the key features in great details.