Study of Deformation Behaviors and Mechanical Properties of Central Diaphragm in a Large-Span Loess Tunnel by the Upper Bench CD Method

Table 1

Construction stage of the upper bench CD method.

Excavation stage	Construction activity	Diagram
I	Excavate Part I, install the sidewall steel rib and central diaphragm steel rib, and construct the foot reinforcement bolt
II	Excavate Part II, install the sidewall steel rib, and construct the foot reinforcement bolt
III	Excavate Part III and install the sidewall steel rib
IV	Excavate Part IV and install the sidewall steel rib
V	Dismantle the central diaphragm steel rib, excavate the core soil of bottom, and install the temporary invert