Method of building strengthened, embanked foundation

Abstract

A method of building a strengthened, embanked foundation capable of forming therein a tunnel comprising steps of burying, during embanking work of lower part of the foundation, a plurality of nets as vertically spaced in embanking material for the foundation at least in its internal zone including side wall portions of the tunnel later formed so as to substantially horizontally intersect imaginary sliding surfaces occurring in the portions upon excavation of the tunnel, forming a crushed-stone arch layer overlying from both upper side portions to upper central portion of the later formed tunnel during further course of the embanking, work providing a hanging support to ceiling wall portion of the later formed tunnel as coupled through hanging rods to the arch layer during its formation, and, after completion of the embanking, excavating a zone defined by the side and ceiling wall portions in the embanked foundation to form the tunnel therein. During this excavation, the imaginary sliding surfaces are subjected to an effective restraining force produced by optimum interlocking of the buried nets with the embanked material, and the side and ceiling wall portions of the excavated tunnel are provided with an effective resisting stress against vertical and horizontal ground pressure resulting from the restraining force and hanging support as well as a self-supporting force of the arch layer, whereby the strengthened, embanked foundation highly stable can be obtained.