田下凝灰岩の長期クリープ試験と構成方程式

1.はじめに

2.実験

 2・1 経緯

 2・2 試料岩石

2・3 実験装置

3.実験結果

 3・1 試験片#1と試験片#2の結果

 3・2 過去の高い応力レベルにおける試験結果との比較

4.構成方程式による検討

 4・1 1次クリープをあらわす構成方程式

 4・2 応力依存性をあらわすパラメータνとn

 4・3 歪増分を考えた構成方程式との比較

 4・4 応力依存性をあらわす関数に関して

5.考察

6.まとめ

引用文献

キーワード:岩石,凝灰岩,クリープ,長期強度,構成方程式,粘弾性


Long-Term Creep Test and Constitutive Equation of Tage Tuff

Two long-term creep tests of Tage tuff were carried out as long as three years. In the tests, specimens were submerged under the water, and creep stress was applied and maintained at 30 % of the peak strength.

The first testing was started in 1994. The result indicated that creep strain rate was monotonically decreasing with elapsed time approximately proportional to (elapsed time)−0.9. Trough the testing period, creep strain was increasing approximately following (elapsed time) 0.1 and did not reach the creep limit to which creep strain leveled off. The second testing was started in 1997 and the result was similar to the first one except that creep strain was slightly smaller than the first. A constitutive equation of variable compliance type was modified especially focusing on the long-term creep at low stress level. Experimental results of not only this study but also previous studies were carefully examined. It was found that the creep strain and strain rate calculated by the modified equation reasonably well coincided with the experimental results.

Key Words: Rock, Tuff, Creep, Long-Term Strength, Constitutive Equation, Visco-Elasticity