Disturbance Deformation of Ground Induced by a Large-Area Piling: A Field Test

When a large-area piling is carried out on the ground adjacent to an existing railway line, the disturbance deformation caused by the piling construction may have an adverse effect on the existing railway foundation. In this paper, a field test with three pile types, consisting of prestressed pipe pile (PPP), micro-grouting pile (MGP), and cast-in-place bored pile (CBP), was carried out to investigate the disturbance response of ground induced by the large-area piling. A high-precision automatic monitoring system was established to measure the lateral displacement and ground surface uplift during the piling process. Test results show that under the same piling range, the disturbance effect caused by the piling of PPPs is significantly higher than that caused by the piling of MGPs and CBPs. The horizontal displacement decreases with the increase of soil depth, and the uplift displacement decreases exponentially with the increase of the distance between the test zone boundary and the measuring points. The maximum influence ranges of the horizontal and vertical displacements caused by the piling of PPPs are about 88d (d is pile diameter) and 30d, respectively, and the maximum influence ranges both of lateral and vertical deformation caused by MGPs and CBPs are less than 5.0 m. Under the same piling range, the maximum lateral displacement caused by PPPs with no pre-drilled hole is three times higher than that caused by PPPs with a pre-drilled hole of depth 15 m, indicating that the pre-drilled hole has a significant control effect on the soil squeezing deformation.