三軸試験による不攪乱マサ土の強度・変形特性

Abstract

It is said that about 13% of the area of our country is covered with granite rock masses ordecomposed granite soils. Granite has played a very important role as a foundation rock mass oras a construction material. The importance has increased and will increase more and more withincreasing large scale construction works.In order to investigate fundamental mechanical characteristics of decomposed granite soil, drained or undrained triaxial tests were performed on undisturbed samples. Some basic physicalproperties were also examined to identify the samples used.A few of main results obtained are as follows:I) Heavily weathered clayey sample behaves mechanically like a sedimentary clay;ii) As to less weathered gravel or sand like samples, mechanical characteristics depend stronglyon the degree of weathering, I.e., weathering reflects on the scatter of the results, on the increase ininitial void ratio, consequently on the decrease in shear strength and the increase in compressibility;iii) Compressibility due to change in isotropic component of stress can be represented by the linearrelation between e and logp;iv) Volumetric strain due to dilatancy which can be evaluated by subtracting the volumetric straindue to isotropic stress component from the measured total volumetric strain correlates well to theconfining stress; andv) Shear modulus increases with increasing confining stress but does not continue to increase forhigh values of confining stress.