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通过回顾Drucker-Prager材料强度参数随内变量变化时应该满足的本构关系,给出在常规三轴试验机工况下的简化表达。选择轴向塑性压应变作为内变量,得到内变量增量与应变增量和应力增量之间的关系,从而得出各试验记录点对应的内变量。为通过多次试验确定对应同一内变量的2个强度参数,把各次试验的应力在均匀离散的内变量点上进行插值,使各次试验对同一内变量按屈服面方程求解强度参数的方程成为可能。得到一种不预设强度参数变化模式也可确定强度参数变化规律的方法。实例分析结果显示试验材料的2个强度参数变化趋势并不一致,不同围压下轴向应力达到峰值对应的内变量也不同,这与围压可提高强度极限并推迟强度极限到来的观点是一致的。
By reviewing the constitutive relationship that the Drucker-Prager material strength parameters should satisfy when the internal variables change, a simplified expression under the condition of a conventional triaxial testing machine is given. The axial plastic compressive strain is selected as the internal variable, and the relationship between the internal variable increment and the increment of strain and the increment of stress is obtained, and the corresponding internal variable of each test record point is obtained. In order to determine two intensity parameters corresponding to the same inner variable through multiple tests, the stress of each test is interpolated at uniform discrete internal variable points, so that the equations for solving the intensity parameters for the same internal variable according to the yield surface equation become possible. A method of determining the variation rule of the intensity parameter without the preset variation pattern of the intensity parameter is obtained. The results of the example analysis show that the trend of the two strength parameters of the test material is inconsistent. The internal variables corresponding to the peaks of the axial stress under different confining pressures are also different, which is consistent with the view that the confining pressure can increase the strength limit and delay the arrival of the strength limit .