Uplift Performance of Plate Anchors in Cement-Stabilised Aeolian Sand

Zengzhen Qian,Mingqiang Sheng,Xianlong Lu,Faming Huang

doi:10.3389/feart.2021.783148

Abstract

Comparative pullout tests were carried out on model plate anchors in uncemented aeolian sand (UAS) and cement-stabilised aeolian sand (CAS) with different embedment ratios of the embedment depth (H) to the width (D) of the plate to examine the effectiveness of the insertion of cement in aeolian sand to enhance the uplift performance of plate anchors. Experimental results demonstrated that significant increases in failure resistance and uplift stiffness can be achieved, irrespective of embedment ratios of H/D, when a relatively small amount of cement (an optimal cement content of 6% by weight of dry aeolian sand determined by direct shear test in this study) was added to the aeolian sand backfill. However, distinct load–displacement responses were observed in all the tests on the model plate anchors embedded in CAS and UAS backfills: two-phase of pre-peak and post-peak behaviour in CAS and three-phase of initial linear, nonlinear transition to peak uplift resistance, and post-peak behaviour in UAS; failure of the former started at tiny displacements and that of the latter appeared at large displacements. Therefore, the significant increases in uplift failure resistance and pre-peak uplift stiffness were limited to relatively low uplift displacements because of the brittle nature of the improved CAS backfills shear strength characteristics.

Highlights

Aeolian sands are fine to medium, non-plastic and uniformly graded materials in many sandy sites, mainly in desert areas, such as Xinjiang, Inner Mongolia, Ningxia, and Gansu Province in Northwest China
It should be noted that the failure can be identified in all the tests on the model plate anchors embedded in uncemented aeolian sand (UAS) and cement-stabilised aeolian sand (CAS); the former started at large displacements and the latter appeared at tiny displacements
Uplift resistance reduces sharply or displacement increases dramatically after the peak resistance is mobilised at an average displacement of 1.20% of the plate width, whereas the average displacement for the model plate anchors embedded in UAS is about 1.64% of the plate width

Summary

Introduction

Aeolian sands are fine to medium, non-plastic and uniformly graded materials in many sandy sites, mainly in desert areas, such as Xinjiang, Inner Mongolia, Ningxia, and Gansu Province in Northwest China. Electric transmission systems spanning from West to East China have been planned in recent years (Qian et al, 2014; Qian et al, 2015; Yang et al, 2019; Yang et al, 2020a; Yang et al, 2020b; Huang et al, 2020, Huang et al, 2021a, Huang et al, 2021b); foundations for four-legged lattice-type transmission towers need to be built in these aeolian sand regions These tower foundations must resist both uplift and compression loading when subjected to permanent and transient load conditions (Pacheco et al, 2008).

Methods

Results

Discussion

Conclusion