Anchor support should be excavated and supported in layers and sections as per the design specifications, ensuring immediate excavation, support, and concrete spraying. Excavation of the next layer of soil should not be conducted until the concrete spraying for the upper working surface is completed. When mechanical excavation is used, it is strictly prohibited to over-excavate the sides or cause soil loosening or damage to retaining structures. To prevent soil collapse on the slope, the following measures can be adopted for soil prone to collapse:
Immediately apply a thin layer of mortar or concrete to the trimmed side walls and drill holes after the mixture sets; install the steel mesh and spray concrete layer on the working surface before drilling and setting soil nails; excavate in small segments along the horizontal direction; first create a slope from the excavated side walls, then drill and set the soil nails before leveling the slope; during excavation, vertically hammer in steel bars and pipes or inject grout to reinforce the soil mass.
