Abstract:

Through cyclic triaxial tests for the reinforced soft clay around the tunnel of Baoshan-Hailun station of Shanghai No.4 subway line, the analysis of pore water pressure was made on the reinforced soft clay under subway train loads. The experiments were arranged by orthogonal and repeated design and the factors which had the influence on the pore water pressure were fully considered, including vibration frequency (0.5, 1.5, 2.5 Hz), amplitude of dynamic stress (20, 30, 40 kPa), consolidation ratio (1, 1.4, 2) and over consolidation ratio (1, 1.5, 2). The test data were processed though the fuzzy theory and the fuzzy method to analyze the influence rate of pore water pressure. The result shows the influence rate of pore water pressure on vibration frequency, amplitude of dynamic stress, consolidation ratio and over consolidation ratio is 0.722, 15.821, 0.944 and 6.628 respectively. Main factors which affect the change of pore water pressure are amplitude of dynamic stress and over consolidation ratio. Consolidation ratio and vibration frequency are not significant.

Key words: cyclic loads, pore water pressure, soil dynamics, dynamic test systems