Reiknforcement effect arising from confining dilatancy and its evaluation

本研究旨在揭示土工合成材料的加固机理。土工合成材料在剪切作用下的约束效应受到重视。围压效应被解释为力学相互作用，使加筋起作用，以防止压实土的膨胀变形。首先，通过一系列土工合成材料加筋土结构的有限元模拟，将土体模拟为考虑压实土剪胀特性的弹塑性材料，试图解释土工合成材料的加筋机理。然而，为了提高数值模拟在实际设计工作中的实用性，作者认识到，应从土体本身的力学特性出发，更准确地理解土与加筋之间的力学相互作用，即加筋机理。然后，对压实砂土(通常为非饱和砂土)进行了一系列室内试验。并进行了室内模型试验。压实土样(直径30厘米，高40厘米)用土工合成材料包裹。试件放置在单轴加载装置上，承受压剪。土工合成材料的广泛应力是在剪切过程中测量的。

This research aims at revealing the reinforcement mechanism by geosynthetics. The attention is paid to confining effect by the geosynthetics under shearing. The confining effect is interpreted as the mechanical interaction such that the reinforcement works so as to prevent dilative deformation of compacted soils. The investigators, first, try to explain the geosynthetic-reinforcement mechanism throughout a series of finite element simulations for geosynthetic-reinforced soil structures, in which the soils are modeled as elasto-plastic materials considering dilatancy characteristics of compacted soils. However, in order to heighten the usefulness of such a numerical simulation in the practical design work, the authors realized that the mechanical interaction between soils and reinforcement, that is, the reinforcement mechanism, should be more precisely understood from a viewpoint of mechanical characteristics of soils itself. Then, a series of laboratory tests for compacted (usually unsaturated) sandy soils is carried out. And some model tests in the laboratory are also performed. Compacted soil specimens (30 cm in diameter and 40 cm in height) are wrapped by geosynthetics. The specimens are laid on the uniaxial loading apparatus and are subjected to compressive shear. The extensive stresses working to the geosynthetics are measured during shear.