Prediction of long term strength of soft sedimentary rock

As the construction of bridges and tunnels on/in soft rocks increases, it has been required to make clear the strength and deformation characteristics of soft rocks. According to the previous works, soft rock is found to be regarded as strain-hardening-softening inelastic and time dependent material with dilatancy(Akai et al.(1977a), Akai et al.(1977b)). Furthermore, new failure criteria were proposed for both peak and residual strengths of the intact soft rock as shown in Fig.l(Adachi et al. (1981)).