| 摘要 |
PURPOSE:To sufficiently strengthen a given area of the ground as well as raise the quality of an injection work by a method in which grout is injected each time a pit is excavated by a rod and also the rod is drawn out by changing the kinds of the grouts for each of the periods. CONSTITUTION:When a pit is excavated by a double-tube rod A having a bit (a) with an excavating blade (not illustrated) on its lower end, a grout Q to improve the gound is concurrently injected. In such an injection work, while injecting a grout Q1 composed of a suspension having a short gelling time (e.g., a cement-based one) from the lower end of the rod A, excavation is advanced to a given position by the rod A. When the rod A is drawn out, a solution-type grout Q2 having good permeability (e.g., a water glass-based one) is injected at a low pressure into the ground. By this, when the rod A goes up, the grout Q2 does not flow to too far places since comparatively large spaces among soil grains are already filled with the grout Q1. Thus, both the grouts Q1 and Q2 can be sufficiently injected into a given area in the ground to be improved and there by the grout can thus be improved and strengthened. |
