Model tests on behaviour of buried pipes in a large soil chamber under cyclic loading

Centrifuge model tests and elastic FE analysis on seismic behavior of buried culverts

“…Normal () and tangential () earth pressures acting on the culvert surfaces, as well as bending strains () produced on the walls of the culverts, were measured. The structure of the model culverts and their instrumentation were detailed in past literature (Tohda et al 2010a). High accuracy in earth pressure measurement was confirmed in all the tests through the good agreement obtained between the measured bending strains and the bending strains calculated under the measured earth pressure conditions, in addition to the fulfillment of the external forces equilibrium, similarly to that presented in the same literature.…”

“…One of the critical differences between the measurement and prediction was the magnitude of the tangential earth pressures () acting on the surfaces of the buried culverts. The measured  were always almost null, while the predicted  were remarkably greater than the measured  (Tohda et al 2010b). These findings showed the necessity to develop a new seismic design method that can represent the actual behavior of buried culverts.…”

“…The authors have investigated extensively the seismic behavior (earth pressure and deformation) of buried culverts with different shapes and flexibilities through dynamic centrifuge model tests (Tohda et al 2010a), and the static centrifuge model tests that simulated simple shear deformation of the ground produced by strong earthquakes (Tohda et al 2013). Special concern was paid in these experiments to measure precisely the distributions of both normal () and tangential () earth pressures acting on model culverts, because the authors believed that the lack of the precise earth pressure data is a critical obstacle to the understanding of the actual seismic behavior of buried culverts.…”

“…Thus, the authors applied an elastic FE analysis to the dynamic centrifuge model tests using four types of model culverts (Tohda et al 2010b), as well as an elastic continuum model analysis of the static centrifuge model tests using circular-type model culverts (Tohda et al 2013). The FE analysis allowed slip and separation at the interface between the soil and culvert.…”

Earthquake Geotechnical Engineering Design

“…Moreover a detailed measurement of the shear stress distribution along the perimeter of the structure is very difficult to our knowledge. Some recent researches (Tohda et al 2010;Chen et al 2010) revealed that the values of the mobilized shear stresses are quite small and slippage at the soil-structure interface is happening even for very low amplitudes of input motion. As the measurement of local shear stresses is quite difficult, further study deemed to be necessary to verify these observations.…”