地工袋應用於擋土結構之探討
Date Issued
2004
Date
2004
Author(s)
葉雅芸
DOI
zh-TW
Abstract
From the reference drawings provided by the concerned department of the government, it is found that among the engineering materials which are used most often are rocks while the ecological engineering method is applied, and this phenomenon results in lack of rock materials in the island. Regarding this problem, it is necessary to seek materials in place of rocks. During this research, the author probed into the earth retaining walls built by piled geotechnical sand bags in order to reduce the use of rock materials.
To obtain the interface design strength parameters of the bags, the author performed a series of direct shear tests of the interface of the bags. First, traditional direct shear tests (10cm×10cm×2.5cm) were performed on two kinds of nonwoven polypropylene of different thicknesses filled with two kinds of sand of different grain sizes to see the influence of thickness of bags, filling materials, humidity of filling materials upon the interface strength. The results show that the friction angle in wet condition is bigger than that in dry condition; the apparent cohesion is bigger while river sand is filled, and the friction angle of thin nonwoven polypropylene is bigger than that of thick nonwoven polypropylene. With the results, the author chose four kinds of geotechnical bags including two kinds of nonwoven polypropylene bags of different thicknesses, PE geotechnical bags, and gunnies to proceed large scale direct shear test (35cm×35cm×60cm) to acquire four different interface strength parameters for design. The outcome of large scale direct shear tests show that the interface strength of the mentioned four materials sorted according to strength is gunny, thin nonwoven polypropylene, thick nonwoven polypropylene, and PE geotechnical bags.
After lab tests, the author performed stability analyses of traditional segmental retaining walls and reinforced segmental retaining walls according to “Design Manual for Segmental Retaining Walls” provided by National Concrete Masonry Association (NCMA). In the analyses, the author limited the width of retaining walls within 2.5m and applied eight different back filling materials. After that, the author brought up the relationship charts of recommended height and width of the mentioned four different geotechnical bags for use of design.
The results of analyses show that the available height of the retaining walls is controlled by interface strength while the interface strength is small; while the interface strength is large enough, the height is controlled by the sliding failure in bottom of the walls, and for soils with bad self-sustaining performance, it is better to use reinforced retaining walls.
Subjects
不織布地工袋
麻布地工袋
地工袋擋土牆
直剪試驗
PE地工袋
界面強度
Geotechnical bag retaining walls
Direct shear test
nonwoven bags
gunnies
PE bags
Interface strength
Type
thesis