Experimental Evaluation of Spatial Variability Effects on Liquefaction-Induced Settlements

Orang, Milad Jahed; Bruketta, Sam; Motamed, Ramin

doi:10.1061/9780784482100.030

Cited by 10 publications

(4 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Recently, an exploratory study based on a series of medium-scale shake table tests was conducted at UNR to correlate the volume of the ejecta to the total settlement of the foundation. The results indicated a linear relationship between ejecta volume and total foundation settlement up to a threshold volume of ejecta, beyond which the increase in the volume of ejecta had no considerable impact on total liquefaction-induced foundation settlement [Jahed Orang et al 2019a]. In this study, it was difficult to measure the amount of ejecta due to the significant water flow to the ground surface; however, based on postshaking foundation settlement measurement, the ejecta appears to contribute up to 17% of the total settlement (i.e., 4.8 cm out of 28 cm).…”

Section: Comparison Of Observed and Estimated Foundation Settlementsmentioning

confidence: 93%

“…The ejecta-induced settlement is manifested by the sand boils on the ground surface. The ground failure indices, along with the correlations between ejecta volume and foundation settlement, can be used to further quantify ejecta-induced settlement [Bray and Macedo 2017]; Jahed Orang et al 2019a]. Researchers have observed that much of the foundation settlement takes place during shaking, indicating a higher contribution of shear-induced mechanisms and partial drainage due to high hydraulic transient gradients [Dashti et al 2010a,b;Bray and Dashti 2014].…”

Section: Liquefaction-induced Foundation Settlementmentioning

confidence: 99%

See 1 more Smart Citation

Shake Table Tests on a Shallow Foundation on Liquefiable Soils Supported on Helical Piles

Orang¹,

Motamed²

2021

PEER Reports

View full text Add to dashboard Cite

Extensive damage to buildings and infrastructure observed during past earthquakes resulting from the liquefaction of shallow saturated soil deposits underneath structures has demonstrated the necessity for further research in the area of liquefaction-induced ground movement effects. This study explores utilizing helical piles as a countermeasure to reduce liquefaction-induced foundation settlement and investigates their seismic performance in liquefiable grounds. Two large-scale shake table test series, one without any mitigation measures and one using helical piles, were conducted using the shake table facility at the University of California, San Diego. During each test series, the soil and superstructure models were extensively instrumented and subjected to two consistently applied shaking sequences. The model ground included a shallow liquefiable layer aimed at replicating the subsurface ground conditions observed in the past earthquakes in New Zealand, Japan, and Turkey. Liquefaction-induced foundation settlement mechanisms are broadly categorized as follows: (1) shear-induced, (2) volumetric-induced, and (3) ejecta-induced. In the first test series (referred to as the Baseline test hereafter), all these three components were realistically reproduced, while in the second test series (referred to as the Helical Pile test hereafter) the volumetric and ejecta-induced mechanisms were mainly mitigated, resulting in significant reductions in the foundation settlement. Results from the first test series (i.e., Baseline test) indicated that the flow velocity due to the hydraulic transient gradient displayed an upward flow in the loose layer, which explains the observed sand ejecta. This series of shake table tests resulted in an average total foundation settlement of 28 cm and 42.7 cm during two shaking sequences. The measured foundation settlements were compared to the estimated foundation settlement obtained from Liu and Dobry [1997] and Bray and Macedo’s [2017] simplified procedures. The observed foundation settlements generally were higher than the estimated values. In the second large-scale test series, an identical test setup to the first test series was used except for a group of four helical piles were attached to the shallow foundation to mitigate liquefaction-induced settlements. In this series of tests, a reduced excess pore-water pressure generation around the group of helical piles was observed and is mainly attributed to the increased relative density around their zone of influence as a result of installation. The foundation supported on helical piles underwent almost no differential settlement and tilt. A significant reduction in the total foundation settlement was achieved during the Helical Pile test series compared to the Baseline test series. This shake table project is the first experimental study that reproduced all the key mechanisms mentioned above including the effects of sediment ejecta, which have not been captured in prior experimental studies. In addition, this series of large-scale shake table tests provides a unique benchmark for the calibration of numerical models and simplified procedures to reliably estimate liquefaction-induced building settlements. Although this study introduced helical piles as a reliable and highly efficient measure to mitigate liquefaction-induced foundation tilt and settlement, the proper design nd application of helical piles in seismic areas still need thorough investigation due to possible amplified superstructure response.

show abstract

Section: Comparison Of Observed and Estimated Foundation Settlementsmentioning

confidence: 93%

Section: Liquefaction-induced Foundation Settlementmentioning

confidence: 99%

Shake Table Tests on a Shallow Foundation on Liquefiable Soils Supported on Helical Piles

Orang¹,

Motamed²

2021

PEER Reports

View full text Add to dashboard Cite

show abstract

“…As can be seen in the Table 1, according to [9], soil types can be categorized based on their relative density. Loose soil tends to have the potential for liquefaction hazards.…”

Section: Relative Density (Rd)mentioning

confidence: 99%

“…[7] assessed the reliability of 1D-Shaking table tests for studying liquefaction. [8][9][10][11][12] conducted shaking table tests to investigate large-scale liquefaction and post-liquefaction behaviour. Overall, these earlier studies have concluded that shaking table tests are a suitable method for modelling liquefaction.…”

Section: Introductionmentioning

confidence: 99%

Experimental analysis of liquefaction potential with variations of soil relative density and earthquake frequency

Salimah,

Alvaro,

Prakoso

et al. 2023

IOP Conf. Ser.: Earth Environ. Sci.

View full text Add to dashboard Cite

The resistance of sandy soil against liquefaction is influenced by its grain size and relative density. This study investigates the potential for liquefaction and settlement resulting from liquefaction. A single axis shaking table was employed, with a displacement of 2.5 cm and a box measuring 400 mm long, 400 mm wide and 600 mm height. Various relative soil densities were evaluated, namely 40%, 50%, 60%, and 70%, along with 1 Hz and 1.2 Hz seismic frequency variations. The experiment used three pore pressure transmitter sensors to measure the increase in pore water pressure (top, middle, and bottom), accelerometer sensors to measure acceleration, and settlement measurements at 12 points. The experimental findings prove a correlation between the relative density of the soil and its liquefaction potential. Increasing the relative density of the soil results in a decrease in settlement, ranging from a maximum settlement of 2.93 cm to a minimum settlement of 1.77 cm. Concerning the variation in earthquake frequencies, higher frequencies correspond to increased soil settlement, showing a difference of 15% to 33%. This study highlights the significance of earthquake frequencies and relative soil density in assessing the potential for soil liquefaction.

show abstract

Large-Scale Shake Table Tests on a Shallow Foundation in Liquefiable Soils

Orang

Motamed

Prabhakaran

et al. 2021

J. Geotech. Geoenviron. Eng.

View full text Add to dashboard Cite

Experimental Evaluation of Spatial Variability Effects on Liquefaction-Induced Settlements

Cited by 10 publications

References 10 publications

Shake Table Tests on a Shallow Foundation on Liquefiable Soils Supported on Helical Piles

Shake Table Tests on a Shallow Foundation on Liquefiable Soils Supported on Helical Piles

Experimental analysis of liquefaction potential with variations of soil relative density and earthquake frequency

Large-Scale Shake Table Tests on a Shallow Foundation in Liquefiable Soils

Contact Info

Product

Resources

About