Civil Engineering / İnşaat Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/13

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Author: search.filters.author.Ecemiş, NurhanSubject: search.filters.subject.Shake table test

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  • Article
    Citation - WoS: 34
    Citation - Scopus: 39
    Influence of Consolidation Properties on the Cyclic Re-Liquefaction Potential of Sands
    (Springer Verlag, 2015) Ecemiş, Nurhan; Demirci, Hasan Emre; Karaman, Mustafa
    The relative density can be used as the main indicator to assess the liquefaction resistance of clean sands. As relative density of the sand deposit increases significantly following the initial liquefaction, one should expect that the soil can improve its liquefaction resistance. However, earthquake records indicate that densified sand can be liquefied again (re-liquefied) at smaller cycles by the similar seismic loadings. This work aims to clarify the counterintuitive finding that, after the first liquefaction, the resulting significant increase in relative density (induced by settlements and variation of the water level) do not necessarily imply an increase in the number of loading cycles for re-liquefaction. In this paper, we present a series of experimental results concerning the cyclic liquefaction and the following re-liquefaction of clean sand deposits. The experimental setup is performed by a shaking table, transmitting one-degree of freedom transversal motion to the soil within the 1.5 m high laminar shear box. At four different seismic demands, the input excitation was imposed three times to examine the influence of the initial distributions of the relative density and the consolidation characteristics on the liquefaction potential of the sand. The re-liquefaction cycles of the sand, which previously experienced liquefaction under the same seismic loadings, show that post-liquefaction reconsolidation of the sand deposits affects the re-liquefaction resistance.
  • Article
    Citation - WoS: 36
    Citation - Scopus: 38
    Simulation of Seismic Liquefaction: 1-G Model Testing System and Shaking Table Tests
    (Taylor and Francis Ltd., 2013) Ecemiş, Nurhan
    In this paper, we focus on the development and performance of the 1-g model testing system to monitor the liquefaction occurrence of saturated soils, under subsequent one-dimensional shake table tests. The system is composed of one-dimensional laminar box, cone penetration system, soil model, system for hydraulic soil pumping to achieve loose soil deposit, instrumentation and associated testing hardware. In order to simulate the free-field conditions in the laboratory, the laminates slide on each other using rollers placed between each laminate. The static calibration test results demonstrate that the friction effects between the laminates and the rollers are satisfactorily low. The loosest and the most liquefiable sand deposit is prepared inside the laminar box by hydraulic filling process and subjected to four subsequent shaking tests at different intensities. First, the laminar box and shake table performance is verified by using time-histories of acceleration and displacement test results. Then, the measured data inside the soil and on the laminates are compared with the numerical model. The previously calibrated numerical model UBCSAND which shows the seismic loading conditions in the free field is used in the simulations. Those shake table test results and the numerical simulations of the box and the soil indicate that the usefulness of the laminar box system for shaking table tests is satisfactory for dynamic model tests in 1-g gravity.