Reinforcement for Upgrading Earth Structures Using Geocomposites under Cyclic Loading

本研究旨在探索一种利用两种或三种不同的土工合成材料组合而成的土工复合材料对交通、海浪和地震等循环荷载作用下土体结构进行加固的方法。本研究的关键词是“混合”和“夹层”，包括以下两个方面：i)研究中使用的材料是将未织造土工合成材料与类似于三明治的机织土工合成材料相结合的混杂材料。ii)在土工合成材料的两侧、上方和下方放置砂垫。为了更好地发挥混合土工合成材料混合土体结构的优点，进行了模型试验和数值分析。本研究的主要发现如下：1)在土工合成材料之间铺设砂垫层形成的夹层结构有助于改善软土mo…。2)砂垫与土工合成材料作为夹层结构相结合，可提高土工合成材料的透气性和透水性。将机织土工合成材料夹在土工合成材料中间的土工合成材料最适合于实现这一目的。3)夹层结构的优点被认为是两方面的：一是增加路堤的稳定性，减少路堤的变形和沉降。4)编制了有限元计算机程序，以考虑土工合成材料的约束对夹层结构路堤变形和稳定的影响。5)提出了一种将水泥砂浆注入夹层结构中的新方法，作为一种很有前途的地基和土工结构加固的混合体系。特别是在交通、海浪和地震等周期性荷载作用下，该系统能有效地增加稳定性和减少沉降量。6)无论是使用土工合成材料，还是将非织造土工合成材料与水泥砂浆灌浆相结合，都可以在海浪作用下产生稳定的加筋护岸。较少

The present study aims at exploring a reinforcing method for upgrading earth structures under cyclic loading induced by traffic, ocean waves and earthquakes by using geocomposites which are manufactured by combining with two or three different kinds of geosynthetics. The keyword in this study is "Hybrid" and "Sandwich" which contains the following two aspects :I) The material used in the study is a hybridized one in which the unwoven geosyntheitc is combined with the woven geosynthetic similar to the sandwich.ii) Sand mat is placed at the both sides, above and beneath the geocomposite. This type can be called a hybrid-sandwich earth structure., In order to accomplish the advantageous aspects of the hybrid earth structure with the hybrid geosynthetic, model tests and numerical analysis were carried out. The following main findings were derived from the present study :1) Sandwiched structures formed by sand mat placement in-between geosynthetics contribute to improvement of soft soils mo … More re markedly than in the case with sand mat only without geosynthetic reinforcement.2) Sand mat placement combined with geosynthetics as a sandwich structure gives rise to improvement of permeability and transmssibity of geosynthetics. The geocomposite in which the woven geosynthetic is sandwiched by the woven geosynthetic in-getween is most suitable for accomplishing this purpose.3) Advantages of sandwiched structures are recognized in the two aspects : the one is increase of stability of embankment and decrease in deformation and settlements of embankment.4) The finite element computer code is formulated to consider the effect of confinement due to geosynthetics into deformation and stability of embankment with the sandwich structure.5) Anew method combined by injecting cement mortar into send mat in the sandwich structure is suggested as a promising hybrid system for upgrading foundations and earth structures. In particular, this system is effective to increase stability and reduce settlements under cyclic loading induced by traffic ocean waves and earthquakes.6) Either the use of geocomposite or the combination of non-woven geosynthetic with injection of cement mortar gives rise to stable reinforced revetments at the coastal area subjected to ocean wave actions. Less