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

在理论上和实验性地研究了对僵硬的地材料（例如更新世粘土，沙/砾石，沉积软岩石和水泥混合土壤）的卸载条件下的变形特性的时间影响。对这种行为的适当预测对于许多实际问题很重要，例如对预加载效应，时间依赖性变形或经受挖掘和解释野外加载测试中卸载行为的解释。从本研究中，通常在本研究中测试的各种僵硬的地貌得出以下结论：1）即使在从一定负载状态下以恒定的负载开始卸载后，即使从一定负载状态开始持续的负载速率，变形速率的增加仍会持续下降。2）当负载水平降低时。负面的，而变形……更多的离子会在蠕变阶段随时间减少，并且在放松阶段的时间随时间增加。关于土地材料的变形特征的时间效应的大多数现有理论都涉及加载阶段的变形。鉴于上述，开发了以下本构模型来解释上述模型。1）新的ISOTACH模型；给定的应变增量分解为弹性和不可逆的成分，而给定的应力分解为无粘性和粘性成分。定义了无粘应力与不可逆应变，卸载等不可逆应变之间的滞后关系。然后，当前的给定应力病史的应力状态由瞬时不可逆菌株及其速率唯一控制。该模型与几种类型的粘土和沉积物sofrock相关。2）TESRA（应变速率和加速度的暂时效应）模型：当前的粘应力是通过相对于不可逆应变而通过不可逆应变的增加以及不可逆的应变率的增加而获得的粘性应力增加而获得的。在这种整合中，考虑到这两种类型的粘应力增量与不可逆应变的衰减。该模型与分级不良的沙子有关。较少的