In this study, a new strain measurement using conductive rubber is proposed. Initially, the influence of temperature change, heat generation, deformation rate, and deformation history against the resistance variation of the conductive rubber were examined. The results showed that the resistance variation of conductive rubber is strongly influenced by the deformation history. Furthermore, the applicability and validity of the strain measurement with the conductive rubber was checked with soft sedimentary rock samples. The experimental work indicated that the relation between the resistance and strain of the conductive rubber is linear. And, this linear relationship covers well from loading point to beyond the failure point of the soft rocks. Therefore, this strain measurement method by conductive rubber is suitable for strain measurement of soft rock samples in the laboratory. In addition, this method has strong possibility to measure the strain of soft materials, such as soil, clay, etc., because of the low elasticity of the conductive rubber.

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This study deals with the development of an effective method for the stabilization of cracked rocks by using the mixture of rock particles and waste of PET resin as glue, so as not to spoil the beauty of the rocks. The method is applied to four kinds of rocks, which are different in the size and the shade of minerals contained. The strength and the appearance of the mixture are examined by changing the ratio of the mass of PET resin to the mass of rock particles and the rock particle size distribution. As a result, it is found that the mixture which possesses the most suitable condition for the strength and the appearance can be made. The field tests are carried out by using the mixture as glue and the workmanship are checked. It is concluded that the stabilization method of rocks proposed is quite valid except for a few plutonic rocks such as granite.

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A series of falling weight deflectmeter tests (FWD tests) and plate loading tests (PLT) were performed in the laboratory to evaluate the stiffness of sand ground and to compare the responses from these two types of loading tests. The plate diameters were 150 and 300 mm for both types of tests. The model ground was made of air-dried poorly graded angular silica sand. The ground stiffness from the FWD tests was larger than the one from the PLT under otherwise the same conditions. It was found that this difference is caused by the fact the plate settlement velocity in the FWD tests is substantially higher, by a factor of about 104, then that of the PLT and due mainly to the following two factors: a) the loading rate effects by material viscosity of the backfill soil; and b) effects of dynamic response of the ground in the FWD tests. The methods to correct FWD test results for these two factors were developed and proposed. The relationships between the plate pressure and the settlement from the FWD tests corrected for these two factors agree rather well with those from the PLT. It is shown that the ground response in FWD tests becomes closer to that in PLT by decreasing the stiffness of the buffer used in the FWD tests. A method to infer the plate pressure - settlement relation under the PLT loading conditions from FWD tests using buffers having different stiffness values is suggested.

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Relative humidity changes by evaporation of soil moisture at ground surface in which high soil suction into soil structure of unsaturated soils has induced. Geotechnical engineers requires to evaluate internal friction angle, Φ, and cohesion, c, as strength parameter for unsaturated soil with high soil suction. This study focuses on Φ and c of unsaturated soil with various soil suction. In the test programs, statically compacted soil specimens were prepared, and three different triaxial tests were performed to examine shear properties. High soil suction triaxial test and constant water content test were conducted to estimate the strength parameters of unsaturated soil specimen. In addition, effective internal friction angle was measured by consolidated drained triaxial tests using saturated soil specimens. As results obtained from three different triaxial tests, it was evident that the internal friction angle of compacted unsaturated soil is obviously similar to that of saturated soil.

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Soil that is generated as a byproduct of construction work but that lacks sufficient strength for use as foundation material without modification has been disposed of as industrial waste. For effective use as a resource, such soil is increasingly being modified with solidification agents and reused as an embankment material. Hokkaido is in cold, northern Japan, which means that soil modified during the winter may not begin to develop strength until the air temperature rises beyond a certain point. Unfortunately, very few studies have addressed how curing temperature affects the ultimate strength of modified soil. To determine those effects, the authors obtained strengths of modified unsuitable soil under various curing temperatures and durations. The following were found: 1) When the curing temperature is constant, the ultimate soil strength achieved by curing at 5°C or -20°C is lower than that achieved by curing at 20°C. 2) When the initial curing temperature is low, great ultimate soil strength can still be achieved if the curing temperature is subsequently raised. 3) When the initial curing temperature is -20°C, the ultimate strength will be small even if the curing temperature is raised afterwards.

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"Development of reinforced earth method using chain as reinforcing material", Jiban Kogaku Janaru (Japanese Geotechnical Journal), Vol. 3, No. 3, pp.273-285 (2008).
On page 273, footer of the page, paper received date 'March 31, 2008' should be 'March 31, 2007'.

The editorial board regrets this error.

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