Anchor used: Temporary Strand Anchor
The foundation pit support project was carried out in Section 3, Jianshe North Road, Chenghua District. It is designed and constructed by Chengdu Surveying Geotechnical Research Institute Co., Ltd. Of MCC whereas Suzhou NG Foundation Engineering Co., Ltd. supplied hot-melt removable anchor products and technologies. The project involved 20 anchor, average 5 strands each, and has length 21 meters long each strand.
1. Construction stage
1 ). Inspected a total of 100 steel strands from 20 groups of anchors to ensure their electrical conductivity before construction.
2 ). After construction, randomly selected 10 anchors due to their working face. All strands were energized normally.
3 ). Tensioned hot-melt removable anchor lock time: 2017.11.23—2017.11.25
After the tension was locked, 10 anchors were sampled and all were energized normally.
2. Removing stage
Hot-melt removable anchor construction period: 2018.04.24 - 2018.05.03
1 ). Inspection was made on each strand before the anchor was removed. As a result, an anchor was found to be seriously damaged. We analyzed it and found out that the strand was damaged when the region around the reserved horse track was excavated. Each of the remaining three anchors had a strand energized abnormally, and the rest are normally energized and removed. The removing process was done by fully automated machine, which is safe and fast.
2 ). Regarded the damaged strand mentioned previously, we removed the clamp and cut off the out-spreading exposed steel strand. Next, we discovered that the conducting wire at the base plate are normally energized and hence we removed it through energizing.
3 ). The recovery rate reached 97% after the damaged steel strand was removed. Next, test was conducted to find out the location of the power cuts of the three strands that mentioned previously. It was found that one of the wires was broken at the position behind the pile. However, we were able to find out the intact wire after breaking the two piles at the middle. Later, removal of the anchors was made via energizing.
4 ). At this stage, the recovery rate had reached 98%. The broken wire was located deep in the anchor hole and hence it was difficult to remove it using normal energizing method. Thus, the two steel strands can be removed by remedy scheme.