ABSTRACT
As a trenchless technique, pipe roof method used to pass roads, railways and airport runways has gained good effects in underground construction engineering such as in Japan, America, Taiwan China etc. The steel pipes are connected by means of interlocks and then form a closed roof. In the gap of interlock, some water-stop material or cement pasted is injected to form a waterproof pipe curtain. After soil reinforced, excavation and brace set are carried out simultaneously, then the structure system is installed until all soil excavated. Alternative is also feasible, like the method of Japanese ESA (endless self-advancing method), which cultivate box is cast beforehand in shaft then pulled each other as soil excavated. Because of the effect of pipe roof, ground settlement decreases dramatically.
