Performance Analysis of Axially Loaded Secant Pile Wall Embedded in Sand: An Experimental Investigation

Abstract

In urban environments, temporary excavation support systems (ESSs) are intensively recommended during the construction process of structures with underground levels to preserve nearby structures and maintain the excavation sides. Once the foundations and basements are constructed, these systems are rendered useless. As a result, integrating the temporary ESS into the building foundation may have significant benefits. Therefore, the main aim of this paper was to investigate the behavior of Secant Pile Walls (SPWs) through fifteen model tests with an acceptable scale on an axially loaded SPW embedded in medium and dense sand. This study considered several factors to define wall behavior, such as normalized lateral deflection (δh/Ht%), the vertical deflection of the SPW (δvw/Ht%), vertical ground settlement (δv/Ht%), and settlement influence zone (Do). These factors were investigated and analyzed under the influence of a set of parameters including normalized penetration depth (He/Hc), sand relative density (Dr), and surcharge load density (Wsur). The findings demonstrated that SPWs had structural and overall stability features to withstand lateral earth pressures as well as applied axial loads. Generally, increasing the He/Hc ratio further than a limit value of 2.0 for the same surcharge load had a limited impact on the ultimate axial capacity, particularly in the case of dense sand. The location of the pivot point (ε′) extended from 0.24 to 0.41He from the wall tip, with a mean value of 0.34He and 0.29He for the values of Dr = 80 ± 2%, and 60 ± 2%, respectively. Other issues were also discussed for selected samples, including an analysis of the wall's bending moments and any potential wall buckling. Finally, to correlate the experimental data with the theoretical values, a modification factor for the pile static formula was developed by using nonlinear regression analysis with a significant prediction accuracy with an R2 of 0.94.

New Displacement Method for Free Embedded Cantilever Walls in Sand

“…The mean wall backfill 12 depth in the test by Chavda 2017 was 250 mm/2=125 mm. The same height was 750 mm/2= 375 mm for the test by Basha et al, 2023. In this case, using Eq. 2, the corresponding soil modulus for the test by Basha et al will be 3000 kPa x (375 mm/125 mm) 0.5 ≈ 5200 kPa (Table 2).…”

“…The formulas cover nominal wall heights of 1m, 2m, 3m, 4m, 5m, 6m, 7m, and 8m. The FE model was validated against laboratory studies conducted by Chavda et al 2017 andBasha et al 2023, and the formulas were also applied to an on-site wall test conducted by Li and Lehane 2010 and a laboratory study by Bica and Clayton 1998.…”

“…The material input parameters of the FE validation in comparison with the actual laboratory test performed byBasha et al 2023 …”

New Displacement Method for Free Embedded Cantilever Walls in Sand

“…The methodology employed in generating these wall configurations is detailed in Section S1. The formulae cover nominal wall heights of 1 m, 2 m, 3 m, 4 m, 5 m, 6 m, 7 m, and 8 m. The FE model was validated against laboratory studies conducted by Chavda et al [20] and Basha et al [21], and the formulae were also applied to an on-site wall test conducted by Li and Lehane [22] and a laboratory study by Bica and Clayton [23].…”

Numerical Modelling of Secant Piles

“…They are particularly useful in urban areas and areas with high groundwater levels. The lateral deflection in the secant pile wall was significantly reduced as the penetration depth ratio increased [14]. Secant piles primary advantage is their ability to withstand lateral loads from the surrounding soil, making them suitable for deep excavations such as basements and subterranean parking facilities.…”