Year: 2017
Anchor used: Removable Multi-Strand Ground Anchor

Project Overview
There are higher piles outside the boundary line of the west and north sides of the foundation pit, and higher backfill on the east side. According to the excavation depth and the strata in different regions of the project, we, NENGGONG uses the SMW (soil mix walls) construction method integrated with compressive stress-dispersive underreamed rotary spray and hot melt removable anchor technology as the bracing scheme. Since the foundation pit is nearer to the boundary on the south side, with excavation depth 7.2m, we planned to use cantilever SMW construction method as bracing scheme. On the other hand, foundation pit uses SMW construction method together with compressive stress-dispersive underreamed rotary spray and hot melt removable anchor bracing scheme. The removable anchor uses compressive stress-dispersive underreamed rotary spray integrated with hot melt removable technology while the jet grouting implements specific rotating speed and drilling depth control. As such, the dispersion of the anchor can be minimized and the recovery rate reached 97.6%. Eventually, the displacement after the excavation was under control and the outcome had met our expectation.

Details
Enclosure perimeter: 632m
Enclosure area: 2134m²
Leveling elevation: 1.80m (Relative elevation-2.15m)
Foundation pit depth: 6.4m-8.0m
Excavation depth: 7.20m
Altitude (based on the altitude of China): 3.3-4.0m
Cushion height : -4.45m
Elevation angle of bearing platform: -5.40
Safety level of the side walls of foundation pit: 6.4m-8.0m, Excavation region marked as secondary level, slope at the boundary as tertiary level
Life-span of pit foundation design: one year