Abstract:

 A new underground structure based on transverse prestress, underground bundled integrate (UBIT), is proposed to address the shortcomings of the pipe curtain method, such as ineffective coordination of steel pipes and low support efficiency, and further expand the benefits of pipe curtain in shallowburied largespan underground structures. However, the research on the building technology and structural performance of the UBIT is still in its early stages. It is crucial to carry out several tests and studies since its structural, mechanical properties, and stresses weak areas are unclear. Based on the engineering requirements and previous literature research, a fullscale experimental study on the shear performance of the bundled integrate structure is conducted to investigate the structure′s mechanical properties and bearing capacity under compression and bending. The findings reveal the following: (1) The structural deflection and joint opening can be categorized into six development stages. (2) The disengagement of joints, partial failure of concrete, clinginess of CT lock, and disengagement of CT lock are key performance indicators of the structure. (3) The structural failure is indicated as the upper CT type lock falls off and is unable to continue to support an external weight. (4) The experimental results of fracture load and ultimate load of structural bearing capacity are close to the theoretical values.