Produced Resisting Pressure of Pressurized Fluid when it is Distributed into Soil-Bed Layer Spreaded Infinitely (I)

In Case of Gas Flow into Moist Soils

Abstract

This paper reports how the pressure produced at the injection nozzle by flowing air or N₂ gas is actually varied according to the size of nozzle port, the degree of soil hardness, and the thickness of soil bed layer. The important results from this experiment were as follows:
1. In a sandy soil with less moisture in which the cohesive force between the soil grains was weak, a spouting phenomenon rising up to the surface taked place. (Phot. 1-a)
2. However, in a moist sandy soil or a clayey loam, the above mentioned spouting was not observed, but around the nozzle port some hollows were found and soil around the nozzle port was shifted. (Photo. 1-b & c)
3. In such a high-moist clayey soil as more than 30% in moisture ratio, horizontal large cracks was made around the nozzle port with a little stream of gas. (Photo. 1-d)
4. The produced pressure at the injection nozzle generally shows such a change as a cubic function vs. the flow rate after plotting on logarithmic graph and it takes a maximum value of produced pressure at a certain amount of flow rate at which some shift of soil around the nozzle port is observed. (Fig. 4)
5. Depending on the continuous variation of the flow rate, the produced pressure seemed to be weakned showing hystericis. In this consequence, if we flow the fluid of small quantity after the flow of large quantity of fluid at one time, we can spread the fluid into soil bed layer with small produced pressure and small energy. (Fig. 5)
6. The harder the solidity of soil became, the stronger the produced pressure grew, because the porosity in its soil became smaller and the larger the flow rate at which the produced pressure showed the maximum value, became. (Fig. 6)
7. The produced pressure was bigger when the layer of soil-bed became thicker, which meaned the distance between the nozzle and the surface of soil. Its rate of increase of the produced pressure was however comparatively small. In spite of the increase of the thickness of the soil bed from 19cm to 39cm, the produced pressure increased only to 1 and half more. (Fig. 8)
8. The produced pressure was almost the same in the change of the nozzle in all directions. Any breakdown of soil had no influence on the change of the direction of injection. Moreover, it is concluded that the breakdown or the movement of the soil just under the surface is not due to a kinetic energy of fluid, but a static energy of pressure. (Fig. 9)
9. The larger the injection nozzle port became, the weaker the produced pressure grew. The produced pressure did not become weaker in proportion to the size eventhough the nozzle port was extremely large. (Fig. 10)