Abstract: To construct metro stations in core urban areas, superlarge crosssection quasirectangular steel pipe jacking is adopted to construct Jing′an Temple station of Shanghai metro line 14. However, because research on the construction technology and stress characteristics of the new structure is still at the initial stage, and the design key points and stress weak points are unclear, the field experimental research is conducted in this study. Water and soil pressure sensors and steel structure strain gauges are arranged to collect the magnitude and variation law of external load and steel structure strain during pipe jacking, and the mechanical performance of the pipe jacking structure under various construction conditions is studied. The results reveal the following: (1) Under the operation condition, the total pressure distribution is uniform and symmetrical, the total pressure at the top is slightly larger than that at the bottom, and the pressure in the lower half ring is roughly reversed Ushaped. (2) Under the condition of synchronous grouting, the slurry sleeve quickly transfers the grouting pressure to the pipeline. (3) Under the secondary grouting condition, the entire ring grouting pressure is approximately 330 kPa, which is 1.56 times higher than that under the operation condition, and the structure is the most unfavorable. (4) The circumferential stress mechanism of the pipe joint is similar to that of the entire ring rectangular frame structure, and the top and bottom of the structure are the most unfavorable stress sections. (5) The longitudinal stress of the pipe joint is small; therefore, it is necessary to note the retreat amount of the pipe jacking tunnel, increase the backstepping reaction force, and implement waterproof measures for the ring joint.

Key words:

large crosssection quasirectangular steel pipe jacking, structural stress, field test, water and soil pressure, grouting load, mechanical properties