| 摘要 |
PURPOSE:To stably control the pressure and flow rate of grout injected and to eliminate an expensive return valve, by a method wherein the number of revolutions of an injection pump is controlled during a time between injection and about completion of injection, and afterward, control is effected by a means of the on-off valve and the throttle of a branch pipe. CONSTITUTION:In a line 5 through which a grout material is injected into a ground 4 from a tank 1 with the aid of an injection pump 2, the line is communicated with an injection pipe 3 through a flow rate detector 8. An electromagnetic on-off valve 21 and a throttle 22 are located in a return pipe 6 which is branched from a line running between the pump 2 and the flow rate detector 8 and extends to a tank 7. A controller 20 causes the injection pump 2 to be driven at the specified number of revolutions till a time t1, and when a pressure in the line 5 exceeds a set pressure, it opens the on-off valve 21 at a time t2 as the number of revolutions of the injection pump 2 is decreased, a part of the grout is returned through the throttle 22, and this maintains a pressure at a specified value. This enables the grout to be injected at a stable pressure and discharge. |
