Table 1.3. Values of soil friction angle, interface friction angle, friction efficiency and interaction coefficient reported in the literature. Soil Type Reinforcement type Soil internal friction angle () Interface friction angle () E Ci References Sand Woven geotextile (PP) 37.5 35.3 0.92 0.92 et al. (2011) Geogrid (PET) 37.5 37.0 0.98 0.93 Uniaxial geogrid 34.6 33.8 0.97 0.43 Nejad et al. (2012) Gravel Woven geotextile (PP) 38.4 26.9 0.64 0.42 Hsieh et al. (2011) Geogrid (PET) 38.4 38.6 1.01 0.88 Geogrid uniaxial 45.8 44.4 0.95 0.71 Nejad et al. (2012) Crushed stone geotextile (PP) 55.0 30.6 0.41 0.36 et al. (2011) Geogrid (PET) 55.0 43.3 0.66 0.58 RCA Biaxial geogrid (PP) 65.0 50.0 0.55 - Arulrajah et al. (2013) RAP Biaxial geogrid (PP) 45.0 40.5 0.71 - Arulrajah et al. (2013) FDS Woven geotextile (PP) 43.0 29.0 0.60 0.32 Goodhue et al. (2001) geotextile (PP) 31.0 29.0 0.90 0.26 Uniaxial geogrid (PET) 44.0 31.0 0.60 - Uniaxial geogrid (PET) 31.0 26.0 0.80 0.44
3.2. Minimum average roll values (MARV) for several index and mechanical/structural properties of the selected geosynthetics. Uniaxial Geogrid Biaxial Geogrid Woven Geotextile Non-Woven Geotextile HDPE PP HTPE PP Test Units Direction MARV Index Properties/ Structural Integrity Aperture Dimensions Nominal mm MD 406 33 n/a n/a XD 17 33 n/a n/a Minimum Rib Thickness Nominal mm MD - 1.27 n/a n/a XD - 1.27 n/a n/a Grab Tensile Strength ASTM D 4632 N MD - - 2113 801 XD - - 1957 - Grab Tensile Elongation ASTM D 4632 % MD - - 12 50 XD - - 6 - Wide Width Tensile Strength (Ultimate) ASTM D 4595 kN/m MD - - 70 - XD - - 70 - Wide Width Elongation ASTM D 4595 % MD - - 9 - XD - - 5.5 - Ultimate Tensile Strain ASTM D 6637 KN/m MD 114 20.5 - - XD - 23.5 - - Tensile Strength @ 5% Strain ASTM D 6637 KN/m MD 52 11.7 - - XD - 14.6 - - Tensile Strength @ 2% Strain ASTM D 6637 KN/m MD 52 6 - - XD - 7.4 - - Trapezoidal Tear ASTM D 4533 N MD - - 801 334 XD - - 801 - Junction Strength KN/m MD 105 - - - XD - - - - Junction Efficiency ASTM D 7737 % MD - 93 n/a n/a XD - - n/a n/a
Figure 4.9. Interface friction angles () between RCA and geosynthetic reinforcements as well as other interface materials reported in the literature are summarized in Table 4.4. Figure 4.9. Interface direct shear results for RCA-Geosynthetic interaction, and respective Mohr-Coulomb failure criteria Table 4.4. Interface friction angles and efficiency factors for different interface materials. Interface type Source Interface friction angle (δ) Efficiency factor (Eφ) RCA-Woven geotextile This 26 0.44 Gravel Hsieh et al. (2011) 26 0.64 Crushed et al. (2011) 30 0.41 Sand Hsieh et al. (2011) 35 0.92 FDS Goodhue et al. (2001) 29 0.60 RCA-Nonwoven geotextile This study 22 0.36 RCA-Uniaxial geogrid This study 36 0.65 Gravel Nejad et al. (2012) 44 0.95 Sand Nejad et al. (2012) 34 0.97 FDS Goodhue et al. (2001) 26-32 0.60-0.80 RCA-Biaxial geogrid This study 39 0.73
to enter the shear box without during test. The value of 39o was observed, representing Eϕ of 73%. Arulrajah et al (2013) reported of 50o between RCA and a similar biaxial geogrid, with an Eϕ of 55%. Other coarser materials, such as sand, gravel, and crushed stone, exhibited ranging from 37o to 44o (Hsieh et al. 2011). Figure 4.10. Extension of the width (left), and height (right) of the nodes located at each aperture corners of the biaxial geogrid. 4.3.2. RAP RAP samples were compacted at 22 oC, 35 oC, and 50 oC, and interface direct shear tests were conducted at room temperature (i.e. 22 oC). Results of large scale interface direct shear tests between RAP and the four selected geosynthetic reinforcements, and their respective failure envelopes are displayed in Figure 4.11. A summary of the values at the target temperatures is provided in Table 4.5. The and Eϕ between RAP and woven geotextile are comparable to values of concrete geotextile (26o at 22 oC) (Koerner 2005), but slightly lower than that of gravel-woven
Yohchia, C. (1997). Practical Analysis and Design of Mechanically-Stabilized Earth Walls – I. Design Philosophies and Procedures. Engineering Structures 22(2000) 793-808. Elsevier Sciences ltda. Yoon, S., Balunaini, U., Yildirim, I., Prezzi, M., Siddiki, N. (2009). “Construction of an Embankment with Fly and Bottom Ash Mixture: Performance Study”. Journal of Materials in Civil Engineering. ASCE. June 2009.