中文摘要：

分析传统空间Mohr应力圆理论,并指出该理论不能完全反映双向受力下（即考虑中间主应力时）岩土类摩擦材料的应力状态。试验表明岩土类摩擦材料包括混凝土、岩石和土体在双向受压下（以压为正,此时σ_3=0）抗压强度大于单向受压（此时σ_2=σ_3=0）抗压强度,由此提出双向受力状态下2个主剪切平面上承载能力比单向受力状态下剪切平面上的承载能力大,其原因在于双向受力状态下的法向应力大于单向受力下的法向应力,从而使摩擦力和黏聚力增大。这表明空间应力状态下最大压应力σ_1随σ_2增大而增大,此时Mohr圆也随之增大。当σ_2从σ_2=σ_3=0增大至σ_2=σ_1时,不仅2个小极限应力圆在变动,而且3个极限应力圆都在不断增大,由此建立适应双向受力下岩土类摩擦材料的空间Mohr应力圆理论。考虑上述特性,将基于传统空间Mohr应力圆理论的等强度能量强度准则发展为变强度能量强度准则,这一准则能很好地反映岩土类摩擦材料在双向受力条件下的强度特性。

英文摘要：

The traditional theory of spatial Mohr stress circle was analyzed in this paper and was found unable to fully reflect the stress state of geo-friction materials under loading in two directions（when consider the medium principle stress）. The tests of the geo-friction materials including concrete rock and soil indicated that the compressive strength under biaxial compression was larger than that under uniaxial compression. The bearing capacity of two main shear planes under loading in two directions was suggested to be larger than that of one main shear plane under unidirectional loading. The reason is that the normal stress in the biaxial stress state is larger than the one in the uniaxial stress state, which leads to the friction strength and cohesion to increase, trl（compression is positive）becomes larger with increasing of σ2, and the Mohr circle becomes larger correspondingly too. Not only the two limit stress circles were changed, but also the three limit stress circles were enlarged when σ2 was increased from σ2 = σ3 = 0 to σ2= σ1. Therefore, the spatial Mohr circle theory of geo-friction materials adapted to bi-directional loading was established. An energy strength criterion based on traditional spatial Mohr stress circle was developed from the constant strength to variable strength criterion, which reflected the strength characteristics of geo-friction materials under bi-directional loading.