Theoretical analysis of horizontal pipe curtains with tight rows

The pre-support of large-diameter pipe curtains plays an active role in controlling the deformation of excavations, and the layout of the pipe curtains can be divided into vertical and horizontal types. Based on the measured data of Pinganli metro station in Beijing, the horizontal pipe curtains with lock are simplified into the elastic thin plates, and the results of the elastic plate theory and the continuous beam theory are compared and analyzed. Finally, the influences of excavation span, height of overburden, wall thickness of steel pipes and elastic modulus of grouting materials are analyzed. The results show: (1) The results of the settlement calculation of the elastic thin plate theory are in good agreement with the measured data both in the settlement trend and in the final settlement, while the calculated results of the simply supported beams and the elastic foundation beams are only in good agreement with the measured ones in the final settlement. (2) Under the same load conditions, the maximum bending moment calculated by the elastic thin plate theory is slightly larger than that of the simply supported beams, but this difference is not more than 10%. (3) The elastic modulus of slurry and the thickness of the steel pipe wall have small effects on the settlement and bending moment of the pipe curtains, while the excavation span and the height of overburden have great influences on the settlement and bending moment of the pipe curtains. The research results may provide a new way to simplify pipe curtains into homogeneous elastic thin plates for calculation, and provide the theoretical support for design of the pipe curtains.