Application Of SMP Strength Criterion In Geotechnical Engineering

Based on the summary of the famous strength criterions or strength envelope models in last century, SMP (Matsuoka-Nakai) strength criterion which is wildly used in soil mechanics is briefly introduced and then brought into the practical calculations in geotechnical engineering in this paper, namely this famous three-dimensional strength criterion is used to modify the classic Rankine soil pressure theory and the formulas of the critical edge load and the critical load.The Rankine soil pressure theory is always accepted as the foundation of calculations of the soil pressure in practice. But as we know, the ignorance of the middle principal stress and the utility of Mohr-Coulomb strength criterion in the two-dimensional stress state make a blemish that the active soil pressure is bigger and the passive soil pressure is litter than the real. The famous SMP (Matsuoka-Nakai) strength criterion in the three-dimensional stress state is brought into the formulas of the Rakine soil pressure and the new formulas is proposed in the three-dimensional stress state in this paper. The distinction between the new modified formulas and the original is also discussed in the chapter two.The formulas of the critical edge load and the critical load are wildly used in the definition of the bearing capacity in practice. For the ignorance of the middle principal stress, the results of the formulas of the critical edge load and critical load which are based on the Mohr-Coulomb strength criterion in the two-dimensional stress state tend to be conservative. The formulas of the critical edge load and critical load are expanded from the two-dimensional stress state to the three-dimensional stress state by using SMP (Matsuoka-Nakai) strength criterion to substitute for Mohr-Coulomb strength criterion, and the new formulas are proposed in chapter three. Compared with the condition of the two-dimensional stress state, the influence of all the parameters to the results of the formulas of the critical edge load and critical load in the condition of the three-dimensional stress state is analyzed in the end of this paper.