Abstract: In the process of soft foundation treatment using dynamic drainage consolidation, the growth and dissipation of pore water pressure play the decisive role. It is not only primary bases to control the construction schedule, but also is an important parameter to ascertain the strengthening depth and evaluate the reinforcement effect. So the model test, it simulated an expressway site conditions, is carried out with test apparatus designed by ourselves. In order to comprehend the variation of pore water pressure under different parameter combination, these parameters include tamping times; tamping energy; hammer weight; hammer bottom’s area and fall distance, the test is divided into several groups. These tests include the pore water pressure of the same or different depths under different or the same tamping times, the pore water pressure of the same depth with different combinations between tamping energy and hammer weight and so on. Research shows that, when keeping tamping energy invariant, increasing tamping times will slower dissipation of pore water pressure. And increasing hammer weight will be more effective than increasing fall distance. The high tamping energy can make pore water pressure has bigger amplitude, and the corresponding reinforcement range will increase. In order to speed up dissipation of pore pressure, construction procedure should adopt the method of “multiple tamping, and successive increase tamping energy”.

Key words: dynamic drainage consolidation, model test, pore water pressure, soft soil foundation, foundation treatment