泥石流应力本构关系

利用作者在专门研制的仪器上进行两相体流变试验所获得的数据，进行了两相体应力本构关系的分析.两相体受剪时的应力是它的液相应力和颗粒应力之和，同时还存在着相间的相互影响.由张量分析结果，本构关系式可采用切变率二次多项式的形式.多项式中的每一项对应着不同的作用机制：切变率的零次项反映颗粒间的接触挤压作用和液相的屈服强度；一次项反映颗粒间的摩擦滑动和液相的粘滞应力；二次项反映颗粒的惯性碰撞作用和液相的雷诺应力.用相关分析建立了每一项的系数与两相体特性间的关系.每一项的颗粒切/法应力比具有不同的数值，其中二次项的应力比较小，数值与Bagnold的颗粒惯性区的值相近，零次项和一次项的比值较大，与宏观粘性区的值相近.在相当于自然界泥石流运动的颗粒特性和切变率条件下，颗粒的碰撞应力可不予考虑，可用具有屈服值的直线方程来表示.

The stress constitutive relation of debris flow

The rheologic data of two phase mixtures obtained by the author has been analyzed to find out the stresses constitutive relation of two-phase flows. The stresses in two-phase flows is the sum of the stresses created by internal action of each phase and the interactions between the liquid-phase and solidphase. According to the tensor analysis, a quadratic polynomial of shear-rate is adopted as the stress constitutive equation. Each term in the polynomial reflects the action of differsnt mechanism. The coefficients of terms in polynomial depend on the characteristics of two-phase mixtures, and determined by nonlinear regression empirically. In the case of natural debris flow, in which the restitution coefficient of grains and shear rate are lower, the collision actions of grains can be neglected, its stress constitutive relation can be simplified as a linear equation with a yield value.