With extensive constructions of highway embankments being worked throughout the country in recent years improvement of the road side slopes with verdure has been the subject of studies. Application of fertilizer is urgently required for effecting improvement of the banks with verdure within a short period of time in order to prevent them from soil erosion in view of the fact that the soil to be vegetated is quite different from that of usual agricultural land, and that very steep slopes are under the plan of improvement with verdure. It is deplorable that application of fertilizer to vegetate the area has so far been almost neglected. In the present paper first the geology of the soil of the embankments in Japan is dealt with respecting the road side slopes, and secondly the plant nutriment for vegetation of the banks is discussed with particular emphasis in detail on the three basic fertilizer elements. Finally the standard amount of fertilizer to be applied is discussed.
Recently in Japan with the development of soil engineering, there have been an increasing number of constructions of fill-type high dams. Since the materials for the construction of these dams are permeable of water, the middle part of the dams is reinforced with impermeable core of clay. It happens sometimes that where clay is not available in the locality the construction of the dams will have to be given up. Once the dam is built the core is seldom repaired even if repair is required. A fill-type dam faced with asphalt was devised in West Germany about 40 years ago on an upstream slope with successful result. This German work encouraged Japanese engineers to design the like, and in Japan today high dams are often constructed with asphalt facing on large scales. This is a new stabilization process of the slope under water, of which the design and work are described in detail in the present paper.
There have been two methods that have been in practice to protect slopes from erosion and rupture caused by rain falls, one is by growing plants on the area, and the other by constructing pavement of concrete, blocks, etc. Growing plants on the area, more especially sodding it, is preferable to the latter both from economical point of view and in consideration of durability of the work i.e. of preservation of natural scenery. Sodding slopes requires lots of human care for extensive periods of time until it begins to show its effect. For it is not easy for sod to flourish on the slope soil. The latticed frame block method which we hereby recommend can surmount this defect of sod; it can make up for its initial defect, and protect the slope from erosion by the work of the surface water, and prevent the seeds of the plants within the squares from being washed off. The latticed frame block method has both the merit of protecting the slopes with its own pressure and the merit of protecting the grass when it is grown. The block itself is a sort of framed block with a L-letter type cross section and a cutwater flange. The blocks placed on the bare slope make a figure of diagonal lattice and divide the broad area into small squares with their cutwater flanges. The surface water in each square, therefore, converges on the latticed frame and drains scattered. Also, the piles driven into the slope at each joining point of the blocks prevent the slope from sliding. Thus the latticed frame block method is considered to have three-fold advantages; protection of the slope with the weight of the blocks, protection of the grass and the effect of utilizing the pile. When the New Tokaido Line was under rapid construction so as to meet the extraordinary demand occasioned by the Tokyo Olympic in 1964, many engineers were deadly earnest in seeking for an effective method to protect the extensive slopes which stretch along the railway. It was the latticed frame block method that successfully met this demand at the time. Since then, the latticed frame block method has been applied in the fill construction of railway, highway, etc., and obtained excellent results in all parts of the country.
The Hamanako Service Area on the Tomei Highwayline is noted for its beautiful scenery, and the area is a sort of ordained by the Government order as scenic zone. For the purpose of protecting it from breaking down of the rock slopes along the main route at the Service Area, the most effective method must be thought of. If such artificial methods as the mortar spray method and the block method were used, there is danger of damaging the scenery. So such a method as to be free from these faults was devised, i.e. to stick the rocks together by a binding agent and so to protect the rocks from breaking down. The binding agent used there in was made of epoxy-resin, which had been used at the preservation works of Meotoiwa in Futamigaura on 1968, which had been accredited to the authors as success. The injection began on the large cracks and then applied to small ones. The viscosity and the hardening time of the agent must be adjusted to the changes with the dimensions of the cracks. At the surface where the binding agent apeared, the fragments of rocks of the same colours were put on. By this method the rock slopes were stabilized and the beautiful natural colours of the rocks have been perfectly preserved.
Irrigation of the soil with water charged with dispersed resin for the purpose of stabilizing it against its erosion is discussed in the present paper, as a method that is considered to be as effective as the commonly practised process of planting it with fast growing grass, and therefore as of promising utility. The synthetic resin emulsion is denatured into the vein of aggregation of particles, and forms films when it is spread over the soil. It is found to be a superior soil stabilizer against its erosion, and superior also in drying time and in germination. If it is mixed, at the initial stage of the process, with hydrophilic synthetic resin sponge powder, it gains in stabilizing efficiency against soil erosion and also in germination. Owing to this last mentioned virtue, this soil stabilizer against its erosion can function also, when it forms layers over the surface of the soil, as artificial cultivation medium, protecting the soil in cold weather from formation of subsoil icicles. It can thus be utilized for the fertilizing purpose to grow grass on the soil too against its erosion.
For the prevention of surface-soil erosion, synthetic resin emulsions are used recently as erosion stabilizer. One way of their utilization is to spray synthetic resin emulsion over the surface soil so that the soil particles may be combined together by the elasticity of the resin to form a covering layer united with the lower layer of the soil and thus prevent its erosion. This method of stabilization is, however, of recent date and there have been but few reports of basic studies that have been made of it, and little is known of the properties of the emulsions themselves as erosion stabilizer. In the present paper is given an account of the studies we have made of the characteristic features of acrylic emulsions with respect to the properties of erosion stabilizer, and especially the water resistance of the soil which was treated with some acrylic emulsions at various temperature. The result obtained is that the effect of erosion stabilizer is closely related to the minimum film-forming temperature (MFT) of emulsion, and that particularly when it is treated under the low temperature, the emulsions of low MFT give a good result.
Organic compounds are absorbed in clay, some on its layer surfaces, some on its edge surfaces, and the others by replacing the cation which was originally present on the clay surface with another. These chemicals combine clay particles to form water proof clay-organic compounds. In the present paper are presented the results of basic studies of clay-organic compounds, that is, the effects of chemicals on the aggregation of caoline, the increasing viscosity of the bentonite- water system, the sedimentation of Kanto loam-water system, and the water proof effect of compacted Kanto loam; and the practical method of applying chemicals to surface coating is dealt with.
The earth slope, natural or artificial, very frequently loses its stability in the course of time, resulting in failure or slippage. In this case, every deterioration of the slope is induced by nothing other than natural alternation of the soil forming the slope. The authors have paid close attention to the exchangeable ions contained in the soil and to the effect of groundwater on the soil at the site. Chemical analysis shows that the soil forming unstable slope is partly saturated with calcium ions or magnesium ions in natural state, and that the artificial soil which is supplied with divalent ions to saturation exceeds the original soil in natural state in shearing strength. We have thus reached a conclusion that the stability of the slope was upset through loss of divalent ions out of the slope soil by seepage water.
Spraying Portland Cement on the surface of slopes is an effective device against erosion, and the efficacy is enhanced by the surface treatment by means of chemicals, fluorides, for example, ammonium silicofluoride, ammonium bifluoride, zinc silicofluoride and magnesium silicofluoride. The treatment with fluorides has been proved as effective in all the test experiments, and the repetition of the spray has been found to magnify the effect though it will cost somewhat higher.
Special attention must be paid to the fill construction where coal ashes are used because they have particular geotechnical properties. Coal ashes are sandy coarse silt and have no plasticity. They have such small specific gravity as 2.1. Compacted coal ashes have strong shearing resistance at the optimum moisture content, but loose coal ashes have the risk of liquefaction when they are saturated. In Hisasue valley in Kawasaki city, an extensive flow slide of fill construction where coal ashes were used occurred in June, 1965. The fill consisted of loose dumping ashes and it collapsed just when it had been saturated by the seeping groundwater to the critical state. In Hodogaya in Yokohama city, a large fill construction has been built with coal ashes with special attention paid to the drainage of groundwater and to the compaction of fill material. The work has proved a success.
Plain specimens made of low carbon steel S20C were tested under tensile fatigue load under the conditions of σmin=5.3kg/mm2 and of σm=22kg/mm2. The stress-strain hysteresis loop in each stress cycle was reproduced on a synchroscope, and its variation was observed throughout the test on each specimen, in which the stress applied to the specimen was picked up from the loop dynamometer, and the strain of the specimen was picked up from the specimen itself, both by using the wire resistance strain gauges. Permanent strain occurring in the specimen was also measured by means of a dial indicator. The following conclusions were obtained through the discussions of the experimental results. As a whole, the variation of the plastic strain amplitude Δεp, which was obtained as the half width of hysteresis loop, showed a similar tendency to that obtained previously on low carbon steels under completely reversed axial load. In some of the specimens, however, some amount of fluctuation of Δεp was observed through the test period, but no systematic periodicity nor any regularity could be found. There existed a linear relationship between the plastic strain amplitude Δεp and the number of cycles to failure N, when plotted on a log-log paper. The linear relationship was also found when the total hysteresis energy W was plotted against N on a log-log paper, where W was defined as W=w·N, in which w was an area of the hysteresis loop. The increase of the permanent strain εp coincided in its tendency with those observed in many previous investigations on fatigue deformation under simultaneous actions of static and repetitive loads. However, no correlation between the variation of Δεp and the increase of εp could be found.
A report is made in the present paper of a series of tests that were conducted by devising a testing apparatus of a rolling cylindrical body. Special attention was paid to both the line contact and the point contact. It was planned to obtain quantitative information ragarding the chracteristics of friction in the rolling contact of the rolling body in the main shaft bearing of aircraft engines, as well as to measure its lifetime. The testing apparatus was designed on the following bases: (1) accurate measurement of the rolling frictional torque and (2) automatic detection of the lifetime of the rolling body by means of an oscillograph. In the present tests the slip ratio was nearly zero. The present tests were performed under static load, and under conditions of dry rolling, water lubrication and #60 spindle oil lubrication. The following conclusions have been obtained from the present tests. (1) From the tests of the line contact of the rolling cylindrical body under static load, the equipment has been found to be satisfactory for performing rolling fatigue tests, and specially for the automatic detection of the lifetime of the rolling body. (2) There are two inflexion points on the characteristic curve of the rolling friction coefficient, which are considered to show respectively the strength of the oil film and the rolling fatigue limit. (3) The three regions thus divided by these two inflexion points are respectively the region of rolling wear, the region of rolling fatigue damage and the region where remarkable evidence points to its complete freedom from rolling fatigue.
The viscosity measurements of polyvinyl acetate (PVAc) in the bulk and in the concentrated solutions were carried out in diethyl phthalate and in cetyl alcohol with capillary and pippet type viscometers in the molecular weight range from 1.34×106 to 7.95×103, the concentration range from 1.0 to 0.106 in weight fraction and the temperature range from 35 to 157°C. In a wide range of the variables covered in this study, the interrelationship of the viscosity of the bulk and solutions of PVAc, η, the chain length Zw, the concentration (Volume fraction v, of polymer) and the temperature T can be represented by the following formulas: The dependence of critical chain length Zc on concentration is represented as; Zc·v=575. The relationship between the viscosity and the chain length was examined further by correcting the effect of free volume. The viscosity date were reduced to the values corresponding to the free volume state for the reference molecular weight by employing the theories and literature values of Ninomiya etal., Fujita etal., and Pezzin. The reduced viscosities were proportional to Zw in the short chain length range where Zw≤Zc. The further reduction based on the concentration dependence of free volume made it possible to superpose the reduced viscosity logarithmically plotted against Zw for different concentrations by shifting them parallel to the horizontal axis. The shift factors were examined by the theory proposed by Onogi etal. The magnitude of the slippage factor in Bueche's theory was estimated with the data in this study. It was considered that the effect of solvent on the slippage factor was relatively small.