Abstract:

Field tests were conducted at a pile-net structure subgrade working point of a certain new railway to investigate the load sharing and transfer between piles and soil in pile-net structure subgrade, also the composition and distribution of tensile force in cushion. In which the deformation of foundation, the pressure at the bottom of embankment, the pore water pressure, the axial force of pile shaft, and the tensile force in grid were tested. We can get the results as follows. Firstly, compaction subsiding is major component of foundation settlement, indicating the subgrade is stable. The thicker the soft soil, the larger the foundation deformation. Secondly, the soil arch exerts fully when the ratio of settlement difference between pile and pile-inter soil to piles net distance is 5.93%. The subgrade load raised later will undertaken by piles completely. Thirdly, the distribution of vertical additional stress along with the depth of reinforced area shapes like a “K”. Fourthly the distribution of tensile force in bar strip shapes like a “M”, and the thicker the soft soil ,the larger the tensile force. Fifthly, the tensile force consists of two parts,. One is caused by subgrade loads, and the other is embankment’s lateral sliding. The two parts must be considered when designing the bar strip.

Key words: pile- net structure subgrade, field test, sharing and transfer of load, tensile force, soil arch