METHOD OF MANUFACTURE OF UNDERGROUND STRUCTURES FROM GROUTED SOIL Russian patent published in 1994 - IPC

FIELD: civil engineering. SUBSTANCE: borehole is drilled by an auger and then washed out by a jet of water and air with pumping-out of pulp. Mortar is prepared, and the obtained cavity in soil is filled with it. Before auger drilling of borehole, an anchor with a flexible spiral reinforcement is secured on the auger. The borehole is washed out stepwise, and in its bottom part the diameter of the washed out zone exceeds the diameter of the wash-out zone of the top part. The mortar is prepared from the pumped out pulp with addition of 8 to 12% of cement, 8 to 15% of sand, 55 to 60% of clay and 0.6 to 2.0% of fibre in it in the form of fibres or flexible intersecting rigidly bound rings. The cavity in soil is filled in two stages, first the bottom part of the cavity is filled, the auger with reverse rotation is lifted to the top part of the cavity with its lesser diameter, and then the last cavity is filled. The pressure of mortar delivery is decreased, and spiral reinforcement is placed along the cavity walls by means of the auger with anchor. EFFECT: facilitated procedure. 3 dwg, 1 tbl