The present paper presents an example of investigation and research made for estimating the quantity of soil sticking to stumps when they are rooted up based on plant growing conditions in land to be cleared. This paper aims primarily at finding the relations between the diameter of stumps (d) and the net volume of stumps (V_n) both on and under the ground and the volume of stumps (V_s) including soil sticking to them. It has been confirmed that these volumes are proportional to the cube of the diameter of stumps. Seventy new stumps with diameters ranging from 7 to 83cm. of Japanese red and black pines growing in volcanic ash soil were used as specimens in the investigation and research, the results of which are outlined below.
(1) The relation V_n=7.4307 d^2.8177 has been found to exist between the net volume and diameter of the stumps. The specimens relevant to this case are shown in Table 1 and Fig. 5 and 6.
(2) The relation V_s=12.0431 d^2.8096 has been found to exist between the volume of the stumps including soil sticking to them and their diameter. The specimens relevant to this case are shown in Table 3 and Fig. 4 and 7.
(3) Table 4 shows the proportion of the main and accessory roots to the volume of the whole stump derived from the specimens shown in Table 1 with regard paid to the root system, from which the features of the root system can be gathered. The proportion of each root the volume of the whole stump with no regard paid to the root system is about 46% for the stump, about 49% for the main root and about 5% for the accessory root. Similarly, the stump on the ground accounts for about 17% of the volume of the whole stump.
(4) Table 5 shows the result of calculation from the regression curves of V_n and V_s of the quantity of soil expected to stick to the stumps when they are rooted up. This table is expected to provide a good reference for estimating the quantity of soil sticking to stumps.

抄録全体を表示

Some problems in the previous test on liquid limit are clarified from the physical point of view in this paper. Among these, the two points of (1) operation of the apparatus usually used and (2) adjustment of remolded soils, must be considered when obtaining a flow curve. As measures for these, the Fall cone method and pF method have been suggested as new improved methods for replacing the conventional method.
The author proposed a new methed of determining liquid limit based on a new interpretation of liquid limit and explains the significance of remolded consolidation coefficient C'_c=f (L_w)

抄録全体を表示

In order to study the problem of increasing soil bearing power after drainage of residual water on clayey paddy field, and of expanding cracks on the tile drained field, it is of fundamental importance to clarify the mechanism with which the properties of clayey soil are changed after receiving repeated action of drying and wetting. Therefore, three clayey soils prepared by kneading and moulding with water content of about the liquid limit were preliminarily dried to various pF of the soil moisture, and observations were made on their slaking property when soaked, and also of shrinking during the subsequent drying cycle after rewettingi
The experimental results are as follows;
1) The change in properties of the clayey soils differs considerably depending on whether the drying stages is up to or above the pF 4 of the soil moisture.
2) When below pF 4 of the soil moisture, the density of clayey soil becomes higher by rewetting and shrinking by the following drying. The soil indicates the most compact condition when preliminary drying in pF 3-pF 3.5 of the soil moisture.
And, the amount of slaking is the minimum after soaking in water.
3) When drying becomes over pF 4 of the soil moisture, the structures of the clayey soils are changed completely. And, rewetting results in very loose structure and the soil does not regain the packed structure by the following drying cycle.
4) The phenomenon explained in 3) becomes marked when soil is dried to pF 5-pF 6 of the soil moisture. And in this case, slaking of the clayey soils after soaking in the water is alsomarked.

抄録全体を表示

It is recognized that earth dams are apt to suffer from a severe seismic damage, as it is often constructed on relatively soft or fragile foundation. In addition to the foundation basis it is constituted by various sorts of soil. It is not ready to make an analysis on vibrational characteristics of earth dams with such complicated properties.
Researchers have handled this problem based on many assumptions so far. The method with the equation of shear vibration, finite element method and two dimensional vibration method with finite difference are the examples of their study. Each analytical method has its own superiority or inferiority in it.
Authors made numerical computation by means of finite difference with equations (1) and (2) slightly modified from the conventional equation of shear vibration. Figs. 4 (a) to (d) show the computed results from the case that the seismic wave with the maximum amplitude of 1 and one cycle period of 30 seconds input into the section of the body with the height of 20 meters and the botton width of 80 meters as assumed in Fig. 1.
Besides, calculations are made for the case that coefficient of viscous damping is neglected in the said equation (1) and for the known shear vibration equation under the same condition as mentioned above. Those results obtained from different cases are compared and studied.
The study concludes that the effect of viscous damping is gradually noticed when the displacement on the crest changes the direction as appeared primarily on the horizontal direction distinctively followed by the effect to upward direction.
It is observed that the displacement resulted from the calculation with the known shear vibration equation is slightly higher than that from the said equation (1) but the displacement distribution coincides well together.

抄録全体を表示

In dam engineering, it is desirable to grasp quantatively the physical properties of the foundations of the foundation ground and for this purpose, various kinds of studies have been carried ont.
The authors measured shock wave velocity under different geological conditions at several dam sites. An observation of these shock wave records have led the authors to consider that it is necessary to analize the waves in order to obtain more knowledge concerning the physical characteristic of the foundation rocks.
In this paper, a method of detecting the affect of structure and properties of foundation rocks on elastic wave is first described and a few examples of records and their analytical results are explained.
The abstracts of the results are as follows.
1) The recorded waves generally consist of two main waves of different frequencies and the intensity of each of these waves differ in accordance with the place recorded. The frequency of the stronger one is about 0.3-0.8 KHz and the other is 1-3KHz.
2) The frequency response of these waves shows that the wave characteristic is greatly affected by geological feature.
3) It also shows that grouting work improves the energy transmitting characteristic of the rock.

抄録全体を表示

As described in the preceding reports, various measures have been taken to prevent and remove copper poisoning in the Watarase River with their respective drawbacks preventing satisfactory results from being obtained. A basic experiment was conducted on a method of filtration by means of river sand, which represents one of the most economical and permanent remedies for copper poisoned water.
The results of the experiment have revealed the following facts:
1. About 80% of the total amount of copper contained in the river water can be removed by sand filtration.
2. Sand filtration is not less effective than the use of zeolite, bentonite and limestone known for strong adsorption of metallic ions as filter mediums.
3. Sand filtration can remove water soluble copper as well as insoluble copper.
4. The result of differential thermal analysis of the film on the filter layer has indicated that allophane, gibbsitic minerals and quartz are contained in the river water.
5. The successful removal of water soluble copper by sand filtration may be ascribed to the removal by filtration of colloidal clay and humus which have adsorbed copper ions contained in the river water.

抄録全体を表示

Problems related to influence of wind on sprinkler sprays are wind drift, amount of evaporation loss, variation in the sprinkling region, etc. As a consequence, geometric pattern form is influenced by these effects directly. The wind condition near the earth's surface is turbulent flow and vary with time. On the other hand, the author introduced the concept of mean wind velocity and theoretically calculated the geometric pattern form of a single sprinkler. Some of the calculated data were compared with the experimental data and the accuracy of the theoretical calculation were confirmed.
1) On flat field
a) On the assumption that the wind velocity is the same as the average wind, the author considered the case of a velocity profile according to logarithmic law.
b) Previous calculated data were used for the calculation of the geometric pattern form of a single sprinkle on flat field under a windy condition.
c) The calculated geometric pattern form shows a shift to the wind direction according to the wind speed.
2) On inclined field
a) On the assumption that the wind velocity is the same as the average wind, the author considerd a case of. uniform velocity distribution.
b) The wind direction is assumed to be parallel to the earth's surface and the x direction. And, the following equations are obtained in the x, y and z
directions:
_??_(5)
_??_(6)
_??_(7)
c) The calculated results show the characteristic geometric pattern form of a single sprinkler on an inclined field under a windy condition.

抄録全体を表示

Quantative analysis was made on the process of increase and decrease of unsaturationizing of porous medium by dissolved gas.
1. In case of changes of pressure as well as changes of temperature in percolating water, critical temperature is determined corresponding to any change of pressure.
Over critical temperature unsaturationizing of pores increases. It was made clear that under critical temperature unsaturationizing decreased.
2. Analysis was made for the process of increase of unsaturationizing by applying the relation on the air solubility for pressure and temperature, namely equation (7). Calculated value and measured value appear to agree considerably well.
3. In case of applying equation (7) for the process of decrease of unsaturationizing, time lag occurs in measued value. Those phenomenon seem to suggest experimentally that it is necessary to consider not only air salubility, but also contactability of air bubbles with liquid, for the process of decrease.

抄録全体を表示

Time lag occurs in measured value compared with calculated value by the method mentioned in the preceding article in the process of decrease of unsaturationizing of porous medium.
This lag seems to result from a supposition that “the mass of absorbable air=the mass of absorbed air.” Therefore in this report analysis was made by introducing contactability of air bubbles with percolating water.
Analysis included following two assumption=s.
1. Contactability Γ is proportional to degree of saturation by air in the pores of porous medium.
Γ=α·S_A
Here α is a coefficient determined by distribution of pores in shape of particles.
2. In time Δt, the mass of dissolved and absorbed air, ΔV_E is given as the product of coritactabilityΓ and the mass of absorbable air ΔV.
ΔV_E=Γ·ΔV=α·S_A·ΔV
As the result of quantitative analysis introducing the two assumptions above mentioned, calculated value and measured value appear to agree considerably well. Therefore it may well be concluded that introduction of the above assumptions is effective.
Thus contactability which is not necessary to be considered in process of increase should be considered in process of decrease. This seems to be evidence that process of increase and process of decrease are essentially different phenomenon. It may also be a cause of hysteresis belonging to unsaturated permeability.

抄録全体を表示