| 摘要 |
The present invention is directed to a method of installing a high-capacity tieback in coarse-grained soil. The method includes connecting a unitary hollow casing to a drill and inserting a prestressing steel tendon within the casing. A lost bit is affixed to one end of the casing. The drill and casing is positioned at the desired location of the tieback and the casing is inserted into the ground by rotating the casing with the drill. The bit is released and grout is pumped into the casing under high-pressure. Once the grout has reached the desired pressure, the casing is extracted by applying a high-torque of at least 12,000 ft.-lbs. to the casing with the drill which overcomes the frictional engagement between the grout and the casing, and by applying a pulling force with the drill.
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