地盤材料の変形特性に対する時間効果の新しい展開

从理论和试验两方面研究了更新世粘土、砂砾石、沉积软岩和水泥土等刚性岩土材料在卸载条件下变形特性的时间效应。这种行为的正确预测是重要的许多实际问题，如预加载效果的评估，时间相关的变形或地面受到开挖和解释卸载行为在现场加载试验。通过对不同刚性岩土材料的试验研究，得出了以下结论：1）从某一加载状态开始，以恒定加载速率卸载后，变形量仍以减小的速率继续增加; 2）当加载水平降低到一定水平时，不可逆变形速率为零; 3）当加载水平进一步降低时，不可逆变形速率为负值，变形量随加载速率的增加而减小; 4）当加载水平降低到一定水平时，不可逆变形速率随加载速率的增加而减小; 5）当加载水平降低到一定水平时，不可逆变形速率随加载速率的增加而减小; 6）当加载水平降低到一定水平时，不可逆变形速率随加载速率的增加而减小 ...更多信息 现有的岩土材料变形特性的时间效应理论大多是从加载阶段的变形来考虑的。1）新的等速线模型;将给定的应变增量分解为弹性和不可逆分量，将给定的应力分解为无粘和粘性分量。定义了加载、卸载等过程中无粘应力与不可逆应变之间的滞回关系。然后，对于一个给定的应力历史，当前的应力状态是唯一控制的瞬时不可逆应变及其速率。该模型适用于几种粘土和沉积软岩。2）TESRA（Temporary Effects of应变速率和加速度）模型：当前粘性应力是通过对不可逆应变的粘性应力增量和不可逆应变速率的粘性应力增量进行积分得到的。在这种集成中，这两种类型的粘性应力增量的衰减与不可逆应变考虑。该模型适用于级配不良的砂。少

The time effects on the deformation characteristics under unloaded conditions of stiff geomaterials, such as Pleistocene clays, sand/gravel, sedimentary soft rock and cement-mixed soils, were studied theoretically and experimentally. The proper prediction of this behavior is important for many practical issues, such as evaluation of preloading effects, time-dependent deformation or ground subjected to excavation and interpretation of the unloading behavior in the field loading tests. From the present study, the following conclusions were obtained commonly with various stiff geomaterials tested in the present study :1) Even after unloading is started at a constant load rate from a certain loaded state, the increase in the deformation continues at a decreasing rate.2) When the load level is decreased to a certain level, the rate of irreversible deformation rate becomes zero.3) When the load level is further decreased, the irreversible deformation rate becomes negative, while the deformat … More ion decreases with time at a creep stage and the load increases with time at a relaxation stage.Most of the existing theories on the time-effects on the deformation characteristics of geomaterials deal with the deformation during loading stage. In view of the above, the following constitutive models were developed to explain the above.1) New isotach model ; a given strain increment is decomposed into the elastic and irreversible components, while a given stress is decomposed into the inviscid and viscous components. The hysteretic relationships between the inviscid stress and the irreversible strain for loading, unloading and so on are defined. Then, the current stress state for a given stress history is uniquely controlled by instantaneous irreversible strain and its rate. This model is relevant to several types of clay and sedimentary softrocks.2) TESRA (temporary effects of strain rate and acceleration) model : the current viscous stress is obtained by integrating with respect to the irreversible strain the viscous stress increment by the increase in the irreversible strain and that by the increase in the irreversible strain rate. In this integration, a decay of these two types of viscous stress increments with the irreversible strain is taken into account. This model is relevant to poorly graded sands. Less