Abstract: Numerous examples of excavation engineering show that surcharge loads around the excavated have a significant impact on the stability of the supporting structures, and the surcharge loads even become the direct cause of some excavation accidents. Overloading or undercounting near the excavation will bring hidden hazard to the safety of the deep excavation. However, if the surcharge is increased unreasonably in the design stage, it will cause a substantial increase in the construction cost of the excavation engineering, and overloading near the side of the excavation has uncertainty, which is greatly affected by construction conditions, surrounding environmental conditions and analysis methods. Therefore, the overload calculation is a more complicated and very important part in the design of excavation engineering. This article analyzes the stability of the outer protective system from four aspects: the magnitude of the surcharging load value, the width of the overload, the depth of the overload and the distance from the excavation edge, which has certain guiding significance for the design.

Key words: Deep Excavation, Surcharge Loads, Supporting Structures, Stability