Volume 8, Issue 4 December 2023

Directors’ research and development activities

The Application of Partial Floating End Bearing Sheet Piles toMitigate Liquefaction-Induced Foundation Settlements
Md Kausar Alam Anik and Ramin Motamed
University of Nevada Reno, USA
Introduction
Liquefaction-induced tilting and settling of buildings founded on top of saturated sandy soils has been a major contributor
to damage in many past earthquakes. These included the 2011 Tohoku Earthquake in Japan, the 2010-2011 earthquakes
in New Zealand, the 2015 Nepal earthquake, and the most recent 2023 Turkey earthquakes. Geotechnical engineers haverecommended the installation of sheet piles near foundations as aneffective strategy to mitigate settlement induced by liquefaction as
illustrated in Fig. 1. However, the cost associated with full-length
sheet piles can be reduced by implementing partial floating sheet
piles (PFS).
Initially, the PFS approach was conceived as a solution to counteract
subsidence caused by the load of a river embankment constructedon soft clay ground within residential areas. This method involved
the combination of partially floating sheet piles and end-bearingsheet piles. The partially floating sheet piles were situated in theliquefiable layer, while the end-bearing sheet piles were supported
by a stable layer. Consequently, the utilization of the PFS techniqueallowed for a reduction in the weight of sheet piles used, cutting it
approximately in half.
However, previous research investigated that sheet piles with gaps
or half-lengths in liquefiable soils did not effectively mitigateliquefaction-induced shallow foundation settlements. To achieve Fig.1. Application of the sheet pile to mitigate
improved performance in reducing liquefaction-induced foundation the liquefaction-induced foundation
settlements, it is necessary to use full-length sheet piles that cover settlement.
the entire liquefiable layer. As a result, our study involved only changing the configuration of the end-bearing portion of
sheet piles to prepare the PFS.

Experimental Program
In this study, the model ground properties were scaled down according to the similitude law, which was obtained basedon a large-scale shake table test. The scaled model comprised three distinct soil layers with different relative densities: a50% relative density top crust layer, a 30% relative density middle liquefiable layer, and an 85% relative density bottom
dense layer. A shallow foundation was placed atop the crust layer, followed by the insertion of sheet piles (both full-lengthand PFS) at 0.625 times the foundation width from the center, utilizing the press-in technique as shown in Fig. 2(i). This
study included five 1g shaking table tests. Test 1 had no mitigation measures (NM). Test 2 used full-length sheet piles (FL),
while Tests 3 to 5 employed partial floating end-bearing sheet piles. For instance, "5-cut" indicates that 5 cm of the endbearing sheet pile was removed to prepare 5 cm of PFS, as depicted in Fig. 2-ii(b).

11Volume 8, Issue 4 December 2023

(i)

(ii)

Fig. 2. (i) Schema�c view of the model ground, sheet pile, founda�on, and structure, (ii) Sheet pile types u�lized inthis study

Performance of PFS against Liquefaction-Induced Foundation Settlements
In this study, the settlement of the shallow foundation is represented in the form of settlement time histories as depictedin Fig. 3a. The maximum foundation settlement was determined from the recorded settlement-time histories in Fig. 3aand then plotted against the corresponding experiment number in Fig. 3b. In Fig. 3b, the installation of sheet piles
resulted in a decrease in foundation settlement. For ‘FL’, ‘5-cut’, and ‘10-cut’ of PFS configurations, the sheet pile achieved
sufficient fixity of bottom into the dense layer when compared to the ‘20-cut’ of PFS. As a result, an increase in PFS ledto a higher maximum foundation settlement.
-120120(b)(a)Test 1 (NM)Test 2 (FL)
Test 3 (5-Cut)

80

Test 5 (20-Cut)-40

Settlement, (mm)Test 4 (10-Cut)

Max Foundation

Foundation Settlement, (mm)-804002001020030

NMTime, (s)

FL

5-Cut

10-Cut20-CutExperiment Number

Fig. 3. (a) Founda�on setlement-�me histories, (b) The varia�on of maximum founda�on setlement with theexperimental number.

Conclusions
The objective of this investigation was a comparative analysis of partial floating end-bearing sheet piles within a modelground, aiming to mitigate liquefaction-induced foundation settlement using a series of scaled 1-g shaking table tests.
The experimental outcomes demonstrated that the foundation settlement measured by installing 25% (5-cut) and 50%(10-cut) of PFS closely approximated the settlement observed with full-length sheet piles. please note our comprehensive
research paper will be presented at the Third International Conference on Press-in Engineering in 2024, hosted inSingapore.

12