Bearing capacity mechanism of non-embedded pile-plank structure subgrade

Sensor components were disposed at the typical section of test subgrade, and the bearing capacity mechanism of non-embedded pile-plank structure in deep collapsible loess foundations was studied by long-term observation.The pile-soil interaction was considered, the concept of comprehensive rotation stiffness was introduced based on the principle of equal stiffness, the vertical and horizontal plane models of the subgrade were installed, and the deformation and mechanical characteristic of the structure were analyzed.Measured result shows that the test value of structural main reinforcement stress agree well with the theoretical calculation value, the difference is about 10%-30%, and the maximum reinforcement stress of 60.60 MPa appears at the cross section of joist.Pile side earth bears about 95% of total load, and no negative friction is produced.The load transfer law of the structure is different from that of traditional subgrade, load can be transferred to deeper bearing layer by pile foundation, which improves the stress state of soft soil section.Half a year, after the laying completion of track construction, the largest accumulated settlement of top surface for bearing plank occurs at the cross section of mid-span, which is 1.0 mm, and meets the requirement of settlement control.