Frictional Behaviour of Reinforcement in Reinforced Earth Fill Materials

Wei, Meijiu (1990) Frictional Behaviour of Reinforcement in Reinforced Earth Fill Materials. PhD thesis, University of Glasgow.

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This thesis reports on an investigation into the interaction between reinforcement and fill in reinforced earth. The theory and development of reinforced earth and previous research work pertaining to soil-reinforcement bond resistance have been reviewed. This investigation was mainly carried out using three different test methods, viz. large shear box tests, laboratory pull-out tests and field full-scale pull-out tests. Three types of reinforcing straps, viz. galvanized ribbed steel, Paralink 500s and Paralink 300s were tested with five different fill materials, viz. Wardley minestone, Wearmouth minestone, Horden red shale, Loudon Hill sand and Methil PFA. The tests were carried out under various conditions of overburden pressure, density, moisture content and strap length. A total of 550 tests were completed and the results obtained from the different test methods, different reinforcing and fill materials and various conditions are compared. The fill-reinforcement friction coefficient was found to be influenced by test method, overburden pressure, density, moisture content, strap length, extensibility and compressibility. Comparing the three test methods, no matter which reinforcement and fill material were used the field full-scale pull-out test produced the lowest friction coefficient. Higher results were generally obtained from laboratory pull-out tests than from direct shear box tests when ribbed steel was used, whereas when Paralink straps were used higher results were encountered from direct shear box tests. Ribbed steel strap produced the highest friction coefficient with Paralink 500s being superior to Paralink 300s, no matter which fill material was used. As regards fill materials, Horden red shale appeared to produce higher bond resistance, while the efficiency of the minestones, the PFA and the Loudon Hill sand varies with the type of reinforcement and test method. The pulling behaviour of Paralink straps in a pull-out test was monitored by using a "piano wire" method. The extensible Paralink straps were found to perform differently from rigid straps. The "piano wire" monitoring method is a readily available method to investigate the pulling behaviour of an extensible strap, strain distribution along a strap being calculated from the results. The strap extensibility is an important characteristic which causes the reduction of the apparent friction coefficient. It is believed that dilatancy and arching play an important part in a pull-out test. However, the arching effect acts differently with rigid ribbed steel and compressible Paralink straps. It increases the normal pressure on a ribbed steel strap, whereas when a Paralink strap is used the normal pressure is reduced. When Paralink straps are used, pull-out tests appear to be more suitable than shear box tests to obtain the fill-reinforcement friction coefficient, since the influence of extensibility and compressibility of a strap is involved in the former tests. A relationship was established between the friction coefficient and the overburden pressure and density for the present used materials.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Civil engineering
Date of Award: 1990
Depositing User: Enlighten Team
Unique ID: glathesis:1990-78079
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 28 Feb 2020 12:09
Last Modified: 28 Feb 2020 12:09

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