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Geomechanics and Engineering
  Volume 27, Number 5, December10 2021 , pages 497-509
DOI: https://doi.org/10.12989/gae.2021.27.5.497
 


Characteristic study of bell-shaped anchor installed within cohesive soil
Arya Das and Ashis Kumar Bera

 
Abstract
    A large deformation FEM (Finite Element Method) based numerical analysis has been performed to study the behaviour of the bell-shaped anchor embedded in undrained saturated (cohesive) soil with the help of finite element based software ABAQUS. A typical model anchor with bell-diameter of 0.125m, embedded in undrained saturated soil with varying cohesive strength (from 5 kN/m2 to 200 kN/m2) has been chosen for studying the characteristic behaviour of the bell-shaped anchor installed in cohesive soil. Breakout factors have been evaluated for each case and verified with the results of experimental model tests for three different types of soil samples. The maximum value of breakout factor was found as about 8.5 within a range of critical embedment ratio of 2.5 to 3. An explicit model has been developed to estimate the breakout factor (Fc) for uplift capacity of bell-shaped anchor within clay mass in terms of H/D ratio (embedment ratio). It was also found that, the ultimate uplift capacity of the anchor increases with the increase of the value of cohesive strength of the soil and H/D ratio. The empirical equation developed in the present investigation is usable within the range of cohesion value and H/D ratio from 5 kN/m2 to 200 kN /m2 and 0.5 to 3.0 respectively. The proposed model has been validated against data obtained from a series of model tests carried out in the present investigation. From the stress-profile analysis of the soil mass surrounding the anchor, occurrence of stress concentration is found to be generated at the joint of anchor shaft and bell. It was also found that the vertical and horizontal stresses surrounding the anchor diminish at about a distance of 0.3 m and 0.15 m respectively.
 
Key Words
    anchor; axisymmetric; breakout factor; critical H/D ratio; FEM; uplift capacity
 
Address
Arya Das:Department of Civil Engineering, Indian Institute of Engineering Science and Technology, Shibpur, Howrah-711 103, India

Ashis Kumar Bera:Civil Engineering, Department of Civil Engineering, Indian Institute of Engineering Science and Technology, Shibpur, Howrah-711 103, India
 

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