AI Insight
This study investigates the bearing behavior of grouted gravel pile composite foundations used to stabilize railway subgrades in karst terrain, where underlying dissolution fractured zones pose serious deformation risks. Through field instrumentation, the authors characterize the grouting-induced improvement mechanism in surrounding soil by monitoring lateral earth pressure and pore water pressure evolution, and describe the load-transfer behavior of single piles via axial force distribution, shaft friction profiles, and load-settlement curves. Under embankment loading, the composite foundation demonstrated controlled settlement, appropriate stress distribution between pile heads and surrounding soil, and limited lateral displacement at the embankment toe, confirming the practical effectiveness of the proposed integrated treatment technology.
Why it matters
Karst terrain underlies large portions of southwestern and southern China, where infrastructure expansion is ongoing, making reliable and validated ground improvement methods essential for safe and cost-effective railway and highway construction. This field-validated approach provides engineers with a replicable methodology and reference data for designing composite foundations in geologically complex karst environments.
by Lingzhi Zhang, Changhe Yan, Chunyong Jiang
The extensive underlying karst in southwestern and southern China presents significant challenges for deformation control in railway and highway subgrades. This paper proposes an integrated technology combining grouted gravel piles with the treatment of underlying karst dissolution fractured zones, along with the requisite construction machinery and procedural sequence. The technology is implemented and validated through a railway subgrade project, involving a series of field investigations. The grouting-induced improvement mechanism in the surrounding soil is revealed through the evolution of lateral earth pressure and pore water pressure. The bearing behavior and load-transfer mechanism of a single pile are characterized by load-settlement curves, the distributions of axial force and shaft friction, and the load-sharing ratio. Finally, the effectiveness of this technology for the composite foundation is confirmed by field performance data under embankment loading, including settlements at the pile head and various soil depths, stress distributions on pile heads and adjacent soils, pore water pressures at different depths, and lateral displacements at the embankment toe.