Experimental study demonstrates structural stability and load sharing in multi-layered water tunnel linings under high internal pressure, indicating viable operational safety.
Key Points
To evaluate the mechanical behavior, lining interactions, and depth-dependent structural response of a multiple-layered tunnel lining system subjected to high internal water pressure.
Conducted theoretical analysis and physical model testing of a three-layer lining system consisting of an outer precast reinforced concrete segment, a middle self-compacting concrete layer, and an inner steel pipe.
Tested structural response under minimum (16 m) and maximum (40 m) burial depths with operational internal water pressure up to 0.75 MPa, monitoring micro-cracking via acoustic emission (AE).
Under increasing internal water pressure, axial pressure decreased while tensile stress increased, with the interior steel pipe effectively bearing primary loads and protecting exterior concrete segments.
Outer linings experienced greater outward displacements and decreased inward displacements during operation.
Acoustic emission monitoring recorded 2,286 counts at 16 m depth and 2,057 counts at 40 m depth, confirming persistent micro-cracking while the composite structure remained elastic and safe under 0.75 MPa design pressure.