LONG-TREM STRENGTH OF WEAK INTERCALATED SOIL IN SOFT ROCK OF BADONG FORMATION

The properties of creep and time dependent behaviours of strength of weak intercalated soils in soft rock of Badong formation are obvious. To study the long-term strength of weak intercalated soils can be useful for stability analysis of the cutting slopes with weak intercalated soils. In order to study the long-term strength of the weak intercalated soils, the strength and creep tests of weak intercalated soils are carried out with a GDS unsaturated triaxial apparatus. It is to find out the effects of matrix suction on strength and creep characteristics of weak intercalated soils from the stress-strain and strain-time curves. Then the isochronous curves method is used to determine the long-term strength of weak intercalated soils based on the creep curves. The results show that the long-term strength of weak intercalated soils is reduced greatly in comparison with the instantaneous strength. The loss rate of strength is between 34% and 62%.The smaller the matrix suction is,the smaller the long-term strength and the greater the loss rate of strength can be. That is to say for the weak intercalated soils of soft rock of Badong formation, the higher the saturability is,the smaller the strength is and the greater the loss rate of strength is.The increasing range of loss rate of strength can increase with the increasing of saturability of weak intercalated soils.