Bearing Characteristics of Permanent and Temporary Combined U-shaped Groove in Clay Foundation
The U-shaped groove structure commonly used in the transition section between railway tunnels and traditional embankments was taken as the research object.Based on the finite element method,the vertical,horizontal,and bending bearing capacity of the permanent and temporary combined U-shaped groove under different aspect ratios were calculated.The failure mode was analyzed,and a dimensionless bearing capacity coefficient calculation method was proposed.The results show that the vertical failure mode of the permanent and temporary combined U-shaped groove structure is still similar to the Prandtl failure mode.The decrease in clay strength gradient and contact surface friction coefficient will reduce the excitation range of the soil,and compared to traditional U-shaped grooves,the maximum increase in vertical bearing capacity can reach 51%.Under the action of horizontal ultimate load,the bottom arc-shaped area and the wedge-shaped shear areas on both sides jointly form a W-shaped failure mode.As the aspect ratio increases,the increase in horizontal bearing capacity of the permanent and temporary combined U-shaped groove increases from 1.0 times to 2.3 times.When the aspect ratio is small,the ultimate bending moment bearing capacity only exists in the bottom spoon shaped failure mode.As the aspect ratio increases,the wedge-shaped failure mode develops to a certain extent.In homogeneous clay foundation,the wedge-shaped failure mode is not obvious,and the spoon shaped failure area mainly consists of the soil at the bottom of the side wall and the soil on the side wall.As the aspect ratio increases,the increase in the bending bearing capacity of the permanent and temporary combined U-shaped groove increases from 1.4 times to 3.6 times.
subgrade engineeringpermanent and temporary combinedU-shaped groove structureclay foundationload bearing characteristics
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