关键词: 加筋土, 红层软岩土石混填路堤, 力学行为, 现场测试, 数值模拟

Abstract: To understand the mechanical behaviours of red bed soil-rock embankment reinforced with gabion, field tests are conducted to obtain soil pressure, the deformations of gabion reinforcement and gabion wall and the potential internal fracture surface. Meanwhile, based on in-situ tests and FLAC3D numerical modelling, a comprehensive analysis is performed to investigate the effects of reinforcement spacing, reinforcement length, compression modulus, strength indicators of foundation soil and compaction of embankment fill on mechanical behaviours of the embankment. Field tests indicate that the tensile strain distribution of gabion reinforcement along the cross-section of embankment is non-uniform. Besides, the internal potential failure surface of embankment is similar to ‘improved simplified double-segment rupture surface’. The deformation of gabion wall tends to be beam bending inside the back plane of gabion wall, whereas external-oriented bulging is outside the back plane of gabion wall. It is found that the vertical earth pressure in backfill at the same level behind the wall exhibits non-uniform distribution. The relationship between the measured earth pressure at the back wall and the height of the wall is non-linear. When the filling height of the embankment is greater than 7.5 m, the horizontal earth pressure along the back wall can refer Rankine active earth pressure value. From numerical simulation, it can be noticed that the effect of the reinforcement spacing and length on the lateral displacement of embankment is significantly greater than on the settlement. As a result, the vertical spacing and horizontal reinforcement length of the gabion reinforcement should be recommended as 0.5-1.0 m and 0.7H-1.0H, respectively. Since the changes in the compression modulus of foundation soil have a significant effect on the embankment settlement, the compression modulus of foundation soil approaches to be greater than 5 MPa for controlling embankment uneven settlement. In the aim of controlling the growth rate of lateral displacement of the gabion wall, soil cohesion should remain higher than 15 kPa. Finally, the compaction degree of embankment fill should not be less than 93%.

Key words: reinforced soil, red beds soil-rock mixture embankment, mechanical behaviour, field test, numerical simulation