坑中坑围护结构优化分析

Optimization Analysis of Retaining Structure in Pit

以某坑中坑工程为依托,从内坑桩长和倾角出发,对传统等长桩+支撑的支护形式进行优化,提出了3种优化方案;通过数值模拟结合现场实测对优化方案的受力和变形规律进行分析,探讨方案的可行性。结果表明,从支护效果来看,3种方案优劣顺序为长短桩>倾斜桩>倾斜长短桩,从工程效益考虑,3种方案优劣顺序为倾斜长短桩>长短桩>倾斜桩;与原方案对比,3种优化方案均可行,且优化方案应优先考虑工程效益;倾斜桩的外斜直桩倾角尽量不小于15°,当桩位移较大时,可设置倾角不小于20°的内斜直桩来大幅减小位移;斜短桩配比对桩的位移影响较大,桩长次之。可减小部分桩径,从而节约造价。

With a pit-in-pit engineering project as an example, the traditional supporting structure of equal-length piles together with support was optimized in consideration of pile length and inclination of internal pit, and three optimization schemes were proposed. The stress and deformation laws in the optimization scheme were analyzed through numerical simulation combined with the on-site measurement, and the feasibility of the scheme was also discussed. The results show that the scheme with long-short piles, the scheme with inclined piles and the scheme with inclined long-short piles are in a descending order according to the support effect;the scheme with inclined long-short piles, the scheme with long-short piles and the scheme with inclined piles are in a descending order according to the project benefit. The three optimization schemes are all feasible compared with the original scheme, and the project benefit should be given priority in the optimized scheme. The inclination of the outward-inclined pile shall be no less than 15° as far as possible. When the pile has a large displacement, the inclination of inward-inclined pile should be no less than 20° to greatly reduce the displacement. It is found that the pile displacement is greater influenced by the ratio of inclined short pile to the inclined long-short pile, followed by the pile length and the pile diameter. Therefore, the diameter of part of piles can be shortened, and the cost can be saved.