Safe and reliable, on the soil disturbance small clearance clearance Pile construction method in the steel casing within the clearance pile and backfill construction, the underground undisturbed soil or damage is not small, the underground soil does not cause disturbance or produce a small The disturbance. As the steel casing on the hole wall support, in the steel casing around the soil stress has not yet released, it has been removed and timely backfill obstacles, the surrounding structures had no effect.