- Title
- Experimental and numerical study of a newly developed compaction-grouted soil nail
- Creator
- Ye, Xinyu
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2018
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Problematic soils are wide-spread in Australia and overseas. In the case of Australia, this hinders the development of its infrastructure. Soil nailing is a practical and proven technique used in constructing excavations, retaining walls and stabilizing slopes, which works by reinforcing the ground in situ with a large number of closely-spaced, fully-bonded inclusions (soil nails). The pull-out shear resistance between the grout and surrounding soil is of primary importance for the design and safety assessment of soil-nailing systems. However, in soil-nailing practice, this factor is still predominantly estimated using field experience rather than a rigorous scientific knowledge of soil-nail interactions. It is thus of significant importance to understand the complicated coupled nature of soil-nail interactions, so as to optimize the design of soil-nailing systems. The main contributions of this thesis are as follows. (1) A novel soil nail, namely a compaction-grouted soil nail, is proposed for the first anywhere in the world. This new type of soil nail combines ideal compaction grouting (achieved by using membrane) with conventional soil nails to enhance the pull-out force of soil nails. (2) An advanced soil-nailing model system is designed. It provides a systematic experimental understanding of the effects of a variety of factors (e.g., injection pressure, injection volume, grout viscosity, soil types, initial soil density, degree of saturation of soil, ground stress conditions and effective confining pressure) on soil-nail interactions. (3) The pull-out behaviors of a compaction-grouted soil nail under different boundary conditions are investigated through pull-out model tests and numerical simulations. Pull-out model tests and numerical modelling were applied as described, with their results, below. Pull-out model tests with different grouting pressure (GP) were conducted. The grout bulb formed from compaction grouting and the subsequent pull-out force, which exhibits a hardening behavior, was investigated. In addition, interface shear tests were performed with the same boundary condition of pull-out model tests, so that the peak pull-out force could be estimated with different GP. Compared to the conventional soil nail, the pull-out force of a compaction-grouted soil nail can be enhanced more effectively by increasing grouting pressure. Lastly, the pull-out behavior of a compaction-grouted soil nail when installed and pulled out under different degrees of saturation (Sr) was studied. The results show that the pull-out force of a compaction-grouted soil nail is higher in a lower degree of saturation due to a larger grout bulb. For the purposes of reliability and economy, a numerical model was established and verified by the results of physical model tests. The pull-out mechanism was numerically studied and parametric studies regarding different shape factors of grout bulb were carried out. Further investigation of the pull-out behavior of a compaction-grouted soil nail with multiple grout bulbs was also conducted. The variations in peak pull-out force and the corresponding pull-out displacement at failure resulting from different diameters of grout bulb and spacing between grout bulbs were also numerically investigated. In addition, preliminary small-scale pressure grouting tests with different grouting pressure and ratios of water to cement (w/c) were carried out to study grout slurry propagation, including the fracture or compaction pattern and shape of the formed grout bulb, under controlled boundary conditions. The results can be used to optimize the grouting parameters for this new soil nail, without use of membranes, in the future.
- Subject
- compaction grouting; soil nail; physical model test; numerical modelling; pull-out force; grouting pressure; degree of saturation; grout bulb; thesis by publication
- Identifier
- http://hdl.handle.net/1959.13/1393829
- Identifier
- uon:33613
- Rights
- Copyright 2018 Xinyu Ye
- Language
- eng
- Full Text
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| Thumbnail | File | Description | Size | Format | |||
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| View Details Download | ATTACHMENT01 | Thesis | 12 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 901 KB | Adobe Acrobat PDF | View Details Download |