E-Defense Shaking Table Test on the Behavior of Liquefaction-Induced Lateral Spreading of Large-Scale Model Ground with a Pile-Foundation Structure Behind Quay Wall

To investigate the behavior of liquefaction-induced lateral spreading of ground and mechanism of its influencing failure of structures, a shaking table test of a large-scale model with liquefiable sand deposit was performed at the E-Defense shaking table testing facility. The model in a rigid container 16 meters long, 4 meters wide and 5 meters high had a pile-foundation structure behind caisson-type quay wall in the deposit. About 900 sensors and other instrumentations were installed with the model, acquiring accelerations, strains, pore water pressures, and even large displacements occurred by extensive behavior. To the model, two-dimensional, horizontal and vertical motions based on the records obtained in the 1995 Hyogoken-Nambu earthquake were applied, generating liquefaction of the deposit and following lateral spreading. The motions also made the caisson overturn to the waterside, resulting in large deformation of its backfill. Such behaviors caused three waterside piles to bend at the same level of the caisson’s mound. The testing result explained the influences of inertial force and ground deformation on the overturn of the caisson and the collapse of the structure. This observation is valuable regarding understanding of this phenomenon because there has been no such data resulting from observation during earthquakes until now

Earthquake Resistance of New Type Viaduct Structure

An experiment and a numerical analysis were carried out in order to examine the earthquake resistance of a new type viaduct structure. The experiment was a dynamic centrifuge modeling which used the viaduct model of the rates 1/50 of a scale. The 3-dimensional finite element analysis was performed in order to confirm the results of the dynamic centrifuge modeling. At the results, new knowledge was obtained with regard to the viaduct structure

Large-Scale Shake Table Test on Lateral Spreading of a Sheet-Pile Wall Model and Its Centrifuge Simulation

The purpose of this test was to realistically reproduce soil liquefaction and the lateral spreading of saturated sand deposits behind the sheet-pile quay walls and the consequent deformation and translation of neighboring pile foundations. Therefore, a shake table test was carried out using a large-scale laminar box on the large-scale shake table in Tsukuba. The inside dimensions of the model were 11.6 m in length, 3.1 m in width and 4.5 m in depth. Next, a dynamic centrifuge test on the behavior of a sheet-pile wall and a soil pile system was conducted to simulate that of a large-scale shake table test as a prototype. The shake table test was performed under a centrifuge acceleration of 15g． The large-scale test results showed that the lateral displacement of the sheet-pile is increased by about 5 seconds during the shaking, while the sheet-pile showed significant lateral spreading for about 200 seconds after the shaking. The centrifuge study generally confirmed that it is possible to simulate a large-scale test for lateral spreading of a sheet-pile wall and its backfill

Liquefaction-Induced Settlements in Sand Deposits

This paper presents a simplified method for estimating the liquefaction-induced settlements of saturated sand deposits. Based on several kinds of undrained cyclic loading tests followed by drained reconsolidation under the different boundary constraint conditions of non-zero and zero lateral strains for different sands, it has been found that there exists a good correlation between the rates of change in \u27surplus void ratio\u27 of sand (difference between initial void ratio and minimum void ratio) after both complete and incomplete liquefaction, and the maximum shear strain induced during cyclic loading. The predicted results have been compared favorably with experimental observations of shake table tests on saturated model sand deposits

Soil-Pile-Structure during Liquefaction on Centrifuge

Larger scale dynamic centrifuge modeling has been used to examine the behavior of a soilpile-structure system during earthquake-induced liquefaction. The model consisting of a 3 x 3-pile supported structure and a saturated sand deposit was constructed in a laminar container with the inside dimensions of 74-cm length, 50-cm height and 34-cm width. Test results show that liquefaction occurred only within a finite zone in the saturated sand deposit subjected to a strong input shaking that corresponds to a maximum earthquake acceleration of 0.3 g induced probably in actual ground, which agrees well with the results of earthquake damage investigation; moreover, larger induced bending strains of foundation piles were concentrated near the interface between liquefied and non-liquefied soil layers. This concentration of bending strain may be attributed to remarkable reduction in shear resistance of liquefied soil layer relat1ve to that of non-l1quef1ed so1l layer