地盤材料の変形特性に対する時間効果の新しい展開

地基材料变形特性时间效应的新进展

基本信息

批准号：
11450180
负责人：
TATSUOKA Fumio
金额：
$ 5.25万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11450180/
关键词：
stiff geomaterial deformation characteristics time effect viscous effect creep stress relaxation unloaded conditions effects of strain rate ひずみ速度ひずみ加速度リラクゼーション ageing

项目摘要

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

从理论上和实验上研究了硬质岩土材料（如更新世粘土、砂/砾石、沉积软岩和水泥混合土）在空载条件下变形特性的时间影响，这种行为的正确预测对于许多实际问题都很重要。，例如预载效果的评估、开挖地面的随时间变化以及现场加载试验中卸载行为的解释，从目前的研究中，可以通过各种方法普遍得出以下结论。本研究中测试的刚性土工材料：1) 即使从某个加载状态以恒定的加载速率开始卸载后，变形的增加仍会以减小的速率继续。2) 当荷载水平降低到一定水平时， 3）当载荷水平进一步降低时，不可逆变形率变为负值，而在蠕变阶段，变形量随时间而减小，而在松弛阶段，载荷随时间而增大现有的岩土材料变形特性的时间效应理论大多涉及加载阶段的变形。鉴于此，提出了以下本构模型来解释上述问题。1）给出了新的等温线模型。应变增量分解为弹性分量和不可逆分量，而给定应力则分解为无粘性分量和粘性分量。无粘性应力和不可逆应变之间的滞后关系。然后，给定应力历史的当前应力状态由瞬时不可逆应变及其速率唯一控制。2）TESRA（临时）。应变率和加速度的影响）模型：当前的粘性应力是通过对不可逆应变积分由不可逆应变的增加引起的粘性应力增量和由在此积分中，考虑了这两种类型的粘性应力增量随不可逆应变的衰减。该模型与级配较差的砂有关。