Pressure Produced when Fluid is Introduced under Pressure into a Soil-Bed Layer (II)
Relation between produced pressure and physical properties of soil
1980 Volume 42 Issue 3 Pages 335-345
Details
1980 Volume 42 Issue 3 Pages 335-345
The object of this experiment is to develop a sub-soiler which injects fluid under pressure in order to break down soil. In this paper, when air among fluid is caused to flow under pressure into a soil-bed layer which is spread infinitely as in a general field, the extent of pressure which was raised at the nozzle port was observed in relation to the physical properties of soil (i. e. porosity, degree of saturation and specific surface etc.). The results of this experiment were as follows;
1. When the general fluid flows out of the nozzle port in the soil-bed layer in three dimensional directions, the degree of resisting pressure produced at the nozzle port is indicated by eq. (44)-in liquid or by eq. (45)-in gas. These results indicate the fundamental relations between the physical properties of soil and the resulting resisting pressure.
2. The cofficient of turbulent flow Λ and the potential constant J in the formulae (44) and (45), both of which were nondimensional, were decided through this experiment. Consequently, the extent of the resisting pressure produced at the nozzle port can be estimated, if the physical properties of soil are known. (eqs. (49) and (50))
3. As the flow rate of air was increased, the produced pressure at the nozzle port generally showed such a change as a cubic function after plotting on logarithmic graph which is shown in Fig. 4. At a certain flow rate, a cavity was generally produced around the nozzle port in the ground. With a larger flow rate, cracks appeared on the surface of the ground.
4. The size of nozzle was inversely proportional to the degree of force of the produced pressure at the nozzle port. However, in this experiment in which the soil-bed layer was 30cm in height, the flow rate which produced large cracks on the surface of the ground was around 13g/s when air flowed in.
5. The nozzle size r which is equivalent to the cavity size indicates the progress of breaking-down in the ground. It had no relation with the hardness of ground. It was chiefly influenced by the type of soil, the moisture ratio in the soil and the height of soil-bed layer.
The writer wishes to express his gratitude to the Hokkaido University Computer Center for allowing him the use of their facilities.
