Soil Engineering and Foundation

Soil Engineering and Foundation ›› 2019, Vol. 33 ›› Issue (6): 683-689.

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Study of Dynamic Characteristics of Mushroom Shaped Short Pile in Rubber-Sand Mixture Composite Cushion

The rubber-sand-mixture soil is usually lack of the required vertical modulus, a short mushroom-shaped pile is then proposed to reinforce it so as to reduce the vertical deformation dramatically under the condition that it has certain isolation performance. The cyclic shear simulation of the mushroom shaped short pilerubber sand mixture (MP-RSM) composite isolation device is carried out by Marc that is a type of finite element software. The effects of different pile crown deviation angle θand pile belly diameter d on the dynamic performance of the composite device and the effect of reinforcement on the vertical deformation of RSM are compared and analyzed. The results show that: 1) when the strain is small, the dynamic shear modulus of MP-RSM composite cushion gradually increases and tends to be flat with the increase of the pile crown deflection angle, while when the strain is large, the influence of the pile crown deflection angle is small; with the increase of the diameter of pile belly, the dynamic shear modulus of composite cushion increases slightly, but the change is not obvious; 2) when the diameter of pile belly is the same, the dynamic shear modulus of MP-RSM composite cushion increases with the increase of the pile crown the damping ratio of composite cushion increases gradually and tends to be gentle under the shear strain; the influence of the diameter of pile web on the damping ratio of composite cushion is not obvious; 3) The composite cushion has variable horizontal stiffness and good hysteretic energy dissipation characteristics, and can effectively reduce the vertical deformation of rubber sand, which can be used as isolation cushion.   

  1. (College of Civil Engineering, Hunan University of Technology, Zhuzhou 412007)
  • Received:2019-02-25 Revised:2019-03-18 Online:2019-12-28 Published:2019-12-28

Abstract: The rubber-sand-mixture soil is usually lack of the required vertical modulus, a short mushroom-shaped pile is then proposed to reinforce it so as to reduce the vertical deformation dramatically under the condition that it has certain isolation performance. The cyclic shear simulation of the mushroom shaped short pilerubber sand mixture (MP-RSM) composite isolation device is carried out by Marc that is a type of finite element software. The effects of different pile crown deviation angle θand pile belly diameter d on the dynamic performance of the composite device and the effect of reinforcement on the vertical deformation of RSM are compared and analyzed. The results show that: 1) when the strain is small, the dynamic shear modulus of MP-RSM composite cushion gradually increases and tends to be flat with the increase of the pile crown deflection angle, while when the strain is large, the influence of the pile crown deflection angle is small; with the increase of the diameter of pile belly, the dynamic shear modulus of composite cushion increases slightly, but the change is not obvious; 2) when the diameter of pile belly is the same, the dynamic shear modulus of MP-RSM composite cushion increases with the increase of the pile crown the damping ratio of composite cushion increases gradually and tends to be gentle under the shear strain; the influence of the diameter of pile web on the damping ratio of composite cushion is not obvious; 3) The composite cushion has variable horizontal stiffness and good hysteretic energy dissipation characteristics, and can effectively reduce the vertical deformation of rubber sand, which can be used as isolation cushion.

Key words: Low-cost Seismic Isolation Technology, Rubber-Sand Mixture, Mushroom Shaped Short Piles, Dynamic Characteristics, Numerical Simulation

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