Numerical Modeling of Granular Anchor Pile System in Loose Sandy Soil Subjected to Uplift Loading

Abstract

During the last few decades various researchers have proposed appropriate experimental and numerical methods to estimate the uplift capacity of granular anchor piles (GAPs) in expansive soils. Surprisingly, very few studies have been performed to determine the uplift capacity of GAPs in loose sands. This paper presents the results of the numerical study to estimate the ultimate uplift capacity of group piles. Numerical analysis is performed using finite element software PLAXIS-3D. The foundation system is assumed to consist of a different number of regularly spaced GAPs installed in loose sandy soils. The analysis examines the influence of factors such as number of piles n and length L to width D ratio, and properties of the granular pile material and compares the efficiency of group of GAP systems of different configurations. Keywords Granular anchor pile Á Finite element method Á Loose sand Á Group piles Á Uplift capacity Notations L Length of a pile (m) D Diameter of a pile (m) c Total unit weight of soil above the water table (kN/m 3) c sat Saturated unit weight of soil (kN/m 3) / Angle of internal friction of soil (°) c Cohesion of soil (N/m 2) m Poisson's ratio E s Elastic modulus of surrounding soil (kPa) E p Elastic modulus of pile material (kPa) E Elastic modulus of plate element (kPa) d Thickness of a plate element (m) S Centre to centre spacing between piles in group piles (m) n Number of piles in a pile group g Efficiency & V. A.

Uplift behaviour of axial granular pile anchor encased with geogrid in cohesionless soil

“…In the case of GGPA, the uplift load increased significantly on increasing length even after L/D ratio exceeds 10 and may be due to the reason that on encasing GPA with geogrid, there xial granular pile anchor is only shaft failure and pile does not bulge due to its confinement in the lateral direction. Similar results of an increase in uplift loading on increasing GPA length have been obtained (Kranthikumar et al, 2016a;Sharma andSharma, 2019a, 2019b).…”

“…The above-mentioned techniques are costly, time-consuming, require expert skills and labor, and thus cannot be used in small projects. The granular pile is an efficient and effective technique to enhance the bearing capacity and lowering the settlement in soft cohesive soils and loose sandy soils (Rao, 1982;Ranjan, 1989;Vidyaranya et al, 2009;Kranthikumar et al, 2016a;Kranthikumar et al, 2016b).The major advantage of the granular pile is that it increases the load-carrying capacity and reduces the settlement and liquefaction by providing drainage path (Kranthikumar et al, 2016a;Kranthikumar et al, 2016b). A generalized model of JEDT 19,2 588 geosynthetics encased granular pile was analyzed, and it was concluded that reinforced granular piles are a better solution to enhance the bearing capacity of the soil and decrease settlement than conventional granular piles (Deb et al, 2007).…”

“…An improvement over the conventional granular piles has been proposed by providing an anchor plate at the base of the granular pile thus making it a granular pile anchor (GPA) (Phanikumar and Ranjan, 1997). GPA is an effective and efficient technique designed to provide resistance to tensile forces in cohesionless soils (Kranthikumar et al, 2016a). A lot of researches have been carried out in the past by varying GPA length and diameter to predict uplift behavior of GPA in expansive soils (Kranthikumar et al, 2016a;Kranthikumar et al, 2016b;PhaniKumar and Rao, 2000;Phanikumar et al, 2004;Rao et al, 2007;Johnson and Sandeep, 2016;Sharma, 2019;Sharma andSharma, 2019a, 2019b;Ismail and Shahin, 2012;Bhardwaj and Singh, 2014;Phanikumar, 2016;Choudhary et al, 2017).…”

“…A lot of researches have been carried out in the past by varying GPA length and diameter to predict uplift behavior of GPA in expansive soils (Kranthikumar et al, 2016a;Kranthikumar et al, 2016b;PhaniKumar and Rao, 2000;Phanikumar et al, 2004;Rao et al, 2007;Johnson and Sandeep, 2016;Sharma, 2019;Sharma andSharma, 2019a, 2019b;Ismail and Shahin, 2012;Bhardwaj and Singh, 2014;Phanikumar, 2016;Choudhary et al, 2017). The uplift capacity of GPA in loose sandy soil increased on increasing GPA length and diameter and modulus of elasticity of surrounding soil (Kranthikumar et al, 2016a). Keeping the aspect ratio (length/diameter) 10 provided maximum uplift capacity of GPA in loose sandy deposits (Kranthikumar et al, 2016b).…”

A State-of-the-Art Review and Numerical Study of Reinforced Expansive Soil with Granular Anchor Piles and Helical Piles

“…Numerical and experimental studies have demonstrated the behavior of helical [43][44][45][46][47][48][49][50] and granular anchor piles [25,32,[51][52][53][54]. However, studies have not examined their anchoring capabilities in expansive soil [55].…”