Kajima Corporation

Chemical Grouting Company, Ltd.

Shunji Jinbo

Mitsuhiro Shibazaki

Hiroaki Kubo

Hiroshi Yoshida

The present invention relates to a consolidating agent injecting apparatus having a nozzle mounted at the end of a pipe. The apparatus is inserted in a guide hole formed in the ground and the nozzle injects a high pressure jet liquid in a radial direction. The injecting direction of the nozzle is downwardly inclined from the horizontal direction within a range from 15 to 45 degrees. The present invention also relates to a ground improving injecting apparatus having first and second nozzles, mounted at the end of a pipe, for injecting a high pressure liquid and a ground improving injection liquid. The first nozzle comprises a plurality of annularly-arranged nozzles. The pipe is inserted into a hole dug in the ground and the high pressure liquid and the ground improving injection liquid are injected from the first and second nozzles. As the pipe is drawn up from under the ground, the ground is dug and grouted and the ground improving injection liquid is injected to form an underground columnar consolidation body and thereby improve the ground. The consolidating agent injecting apparatus and ground improving injection apparatus of the present invention form a consolidation body of a large section area for improvement of the ground, without transitions of the jet streams to turbulent flow.

Consolidating agent injecting apparatus and injecting apparatus for

The present invention relates to a method for improving the ground of a large area. The method comprises the steps of inserting a pipe into a hole previously dug in the ground, injecting a high pressure liquid and a ground improving injection liquid from an injecting apparatus attached to the tip of the pipe, drawing up the pipe, grouting the ground, and injecting the ground improving injection liquid to thereby form an underground columnar consolidation body for improving the ground. The drawing-up operation of the pipe is executed while applying vertical vibration to the pipe. Thus, a consolidation body of a large area for improvement of the ground is obtained without concave and convex portions.

Method of improving ground of large area

The present invention relates to a method of improving the ground of a large section area. A double pipe, having a first nozzle directed in the lateral direction and a second nozzle surrounding the first nozzle, is inserted into a hole dug in the ground. A ground improving agent is injected at high pressure from the first nozzle through one pipe of the double pipe. A reproduced slurry, obtained by reproducing grouted slimes, is injected from the second nozzle through the other pipe of the double pipe at a lower pressure than the pressure of the ground improving agent. While rotating, the double pipe is lifted up from under ground. The ground improving agent, injected at the high pressure, is surrounded by the reproduced slurry injected at the lower pressure. The frictional resistance between the ground improving agent and the sediments is reduced, the arrival distance of the ground improving agent is increased, and the abrasive effect is obtained. Instead of surrounding the first nozzle, the second nozzle can be arranged at a position closer to the first nozzle. Further, a triple pipe, having the first and second nozzles and a third nozzle surrounding the first and second nozzles, can be inserted into the hole dug in the ground. The ground improving agent is injected at high pressure from the first nozzle through a first pipe in the triple pipe. The reproduced slurry, obtained by reproducing the grouted slimes, is injected from the second nozzle through a second pipe in the triple pipe at a lower pressure than the pressure of the ground improving agent. A gas is blown out from the third nozzle through a third pipe in the triple pipe. While rotating, the triple pipe is lifted up from under the ground. Both the ground improving agent injected at the high pressure and the reproduced slurry injected at the lower pressure are surrounded by the gas. This method results in reproduction of the grouted slimes, assurance of the necessary injection amount of the grouting ground improving agent, and suitabloe jet stream dynamic pressure distribution.

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Koyama, Japan

Shunji Jinbo