Computing Methods Of The Equivalent Stiffness Of The Interior Bracing And The Penetration Depth In Rock Of Rock-Socketed Piles For Deep Excavation

With the urban development, retaining structures for deep excavation are becoming so diversified and complicated that a large number of problems still exist to be solved, though more concerns have been put on the areas for a long time. The computing methods of the equivalent stiffness of the interior bracing and the penetration depth in rock of the rock-socketed pile for deep excavation are two of these problems to be investigated.First, the factors influencing computation of the equivalent stiffness of interior bracing structures are investigated. Then, based on the equilibrium analysis of the penetration part of rock-socketed pile, computation of the penetration depth in rock of the rock-socketed piles is analyzed. Finally, the detailed computing procedure is analyzed for the rock-socketed supporting piles for deep excavation.The following conclusions can be drawn from this dissertation.(1) The equivalent stiffness of the interior bracing of the deep excavation tends to become larger with increase of the element length of the circum-beam and the stiffness of the constraint springs, and the equivalent stiffness tends to become smaller with increase of the spacing of the constraint springs. Constraint direction of the springs and the element length of the bracing except the circum-beam hardly have any influence on the equivalent stiffness. The appropriate values of the influencing factors mentioned above and the constraint direction of springs are suggested for the numerical computation.(2) In view of the stability of rockmass, formulas of computing the penetration depth in rock of rock-socketed piles for deep excavation are deduced. The method for computing the penetration depth in rock of the retaining rock-socketed piles is proposed. (3) The penetration depth in rock of the retaining piles is greatly influenced by the rockmass. The disturbance factors D,the Geological Strength Index(GSI) and the uniaxial compressive strength of the rockmass(σc) have a more significant effect on penetration depth than the Hoek-Brown parameter mi for the intact rockmass and the elastic modulus of the rockmass(Er).(4) Based on the computing method of penetration depth in rock, the dissertation has put forward the detailed procedure for computing internal force and deformation of supporting rock-socketed piles. An example is analyzed according to the procedure. The depth of penetration in rock computed according to the procedure mentioned above satisfies not only the stability of rockmass but also the equirement of internal force and deformation of the retaining piles.