Multi-point shaking table test of the free field under non-uniform earthquake excitation

Abstract

A series of shaking table tests of model field were conducted using four shaking tables. Details of experimental setup are first presented with particular focus on design of the similitude ratio, the 40-m-long model boxes, and the synthetic model soil. The experiments were conducted in two phases: Phase 1 is shaking table test of the model boxes without soil; while Phase 2 is the model field shaking table test. Test results including response acceleration and its spectrum are discussed. The comparisons show that non-uniform excitation in different wave form, peak acceleration, vibration direction and wave propagation direction may lead to different dynamic response. The wave passage effects caused by earthquake should be considered in study of seismic response of long-shape field.

Multi-point shaking table test for long tunnels subjected to non-uniform seismic loadings - part II: Application to the HZM immersed tunnel

“…1/58) is comparatively larger than the other ones. In addition, results obtained from the free field test also indicate the model soil at E9 response greater than others, as can be found in [12].…”

“…Note that before the model test, the free-field test is firstly conducted to investigate the boundary effect of the model container and it is found that the designed model container does not impose significant boundary effect. A detail review of the free-field test can be found in [12]. To provide a global understanding on the seismic performance of the tunnel and yet limit the amount of data included in the paper, the following discussion of test results is focused on acceleration responses of the soil-tunnel system, extension and closure of immersion joints, comparison of results under uniform and non-uniform earthquake input, and seismic performance evaluation of the tunnel.…”

“…Through a series of trial and error cyclic triaxial tests conducted in the laboratory, a mixture with mass content of 1:2.5 of sawdust and sand was found to best match the similitude relations. The properties of the model soil can be found in [12]. The test results indicate that the model soil reproduces well the dynamic properties of the soil in the field.…”

“…The similitude relations used in the tests are listed in Table 1. Detailed description of the similitude relations can be found in [12].…”

“…Details of the test design, as well as the choice of the soil model can be found in [12]. Note that the similitude ratio for the geometry was 1/60, given the length of test, 40 m, and the length of the research area highlighted in Fig.…”