关键词: 深基坑, 钢管桩, 支护设计, 监测方案

Abstract: In view of the characteristics of pebbles in the deep foundation pit area of Zhangjiakou mountain relay center project of Beijing 2022 Winter Olympics, it is difficult to drive steel sheet piles into the supporting structure, and the use of reinforced concrete protective piles has long construction period, high cost and no environmental protection. Through scheme comparison, the support scheme of large-diameter steel pipe piles combined with small-diameter rotary jet grouting piles for water stop is finally determined, which can be recycled and reused so as to save the costs. In addition, considering the greater resistance of strongly weathered rock strata, the embedded depth of steel pipe piles is set at 1.4m, and a two-layer anchor cable system is designed. The calculation results show that the stress and deformation of the steel pipe pile meet the requirements, and the calculated horizontal displacement of the steel pipe pile is 5.16mm, which is very consistent with the measured value of 4.6mm, which indicates that the calculation of the supporting structure can reflect the actual stress state. As the rotary-jet pile is used as the stop-water curtain, there is no water at the bottom of the pit, which indicates that the water stop-water effect of the supporting structure is good during the rainy season construction. In addition, the construction monitoring scheme ensures the safety of the whole construction process and verifies the calculation results.

Key words: deep foundation pit, steel pipe pile, support design, monitoring programme