1. When foundation pit depth, additional load, deformation control value and soil layer character are different, reference section should be divided according to actual condition, which should be calculated under its adverse condition.
2. Calculation of supporting structure should stipulate specific supporting structure construction and foundation pit excavation sequence. Supporting structures and components should meet design requirement of ultimate limit states and serviceability limit states under all working conditions.
3. As for expansion land layer, when designing supporting structure, the influence from side wall on structural force and pit wall protection should be considered.
4. During using period of supporting structure, the change of surrounding environment condition, underground water and soil property influencing on force condition of supporting structure should be considered, and supporting structure’s durability should be considered.
5. Design of supporting structure should consult experience from near engineering under similar condition.
If soil texture is poor or foundation pit is too deep, anchor bolt（Perno de anclaje
） is necessary to support. With increase of foundation pit depth, the length of anchor bolt should be increased accordingly. Anchor bolt combines drilling, grouting and anchoring together. It bonds surrounding soil with anchor bolt, which enhances intensity, integrity and deformation resistance.