PED – 120

*PED120*

II Semester M.E. (Civil) (Geotech. Engineering) Degree Examination, January 2015 (Semester Scheme) 2K8Gt 205/2K8Ct 206 (E – II)/2K8EQ 206 (E – II) REINFORCED SOIL STRUCTURES Time : 3 Hours

Max. Marks : 100

Instructions : i) Answer 3 full questions from Part – A and one question from Part – B. ii) Missing data may be assumed suitably. PART – A 1. a) Discuss briefly on the development stages of reinforced soil structures.

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b) With the help of Howe’s beam analogy explain the mechanism of reinforced soil structures. 10 2. a) List and explain the factors influencing the performance of a reinforced soil structure. 10 b) What are Geosynthetics ? Explain their application potential.

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3. a) What is soil nailing ? Explain their advantages and disadvantages.

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b) Explain the modes of Bearing capacity failure in reinforced soils.

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4. a) Explain the following tests conducted on Geosynthetics. Also comment on their field application : i) Permittivity and transmissivity test ii) Trapezoidal tear strength test 5. Write notes on the following :

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(5×4=20)

i) Types of reinforcements ii) Natural Geo-textiles iii) Application areas of reinforced soils iv) Construction methods for R.E. wall. P.T.O.

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PART – B 6. Design a reinforced soil slope with the following data : i) h = 10 m, β = 75°, W = 12 m ii) γ d = 20 kN/m3, ϕ γ = 28° iii) NOD surcharge, ( γ 0 )d = 0.25 iv) td = 100 yrs, Td = 25°c v) Index strength in kN/m

100

Reference strongly in kN/m 50

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s vi) fsf = 0.6, as = 0.5, a B = 25 b

vii) Take fd = 1.15, f cnv = 1.20, fm = 1.50. Use design chart provided in Fig. 1.

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7. Design a continuous foundation that will carry a load of 500 kN/m. Use the following parameters i) Soil : γ = 19 kN/m3, φ = 30°, E s = 3×104 kN/m2, μs = 0.35 ii) Reinforcement ties : fy = 2.5×105 kN/m2, φ0 = 20° F ⋅ S (B) = 3.0, F ⋅ S (P) = 2.0

iii) Foundation : Df = 1.0 m, allowing bearing capacity = 160 kN/m2 iv) Design life : 50 years.

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