Abstract:

By using GDS stress-controlled triaxial instrument to simulate the roadbed filling process, the variation characteristics of pore pressure, strain, stress path and strength were studied by controlling the drain valve and loading rate. The test results show that each mechanical index has less change at initial roadbed filling under different test conditions, so that the variation of mechanical index depends on the initial consolidation state. Comparing the developments of every curve change from the second shear stage, undrained loading condition makes the effective stress decrease rapidly because the pore pressure cannot dissipate but increase sharply. Fast loading makes increment of pore pressure and roadbed strain large, and makes the foundation strength decreased, which is unfavourable to the stability of roadbed. Oppositely, slow loading let foundation strength decrease slowly but will add loading time and detain construction time.

Key words: turfy soil, roadbed filling, pore pressure, mechanical properties