Q5 a) The discontinuity characteristic mostly dominates failure in the rock mass. Thus, the selection of stabilisation must be made based on the mode of instability. Answer the following question: a) Figure Q5(a) shows two types of failure modes in rock; rockfall and wedge failure. State the rock mass characteristic that contributes to these failures and propose a suitable stabilisation measure for both cases? &UTM M M B) It is a comm on practice to install shotcrete and wire mesh together. For an unstable slope face, why such practice is highly recommended. What is the purpose of wire mesh in shotcrete installation?

Q5 a) The discontinuity characteristic mostly dominates failure in the rock mass. Thus, the selection of stabilisation must be made based on the mode of instability. Answer the following question: a) Figure Q5(a) shows two types of failure modes in rock; rockfall and wedge failure. State the rock mass characteristic that contributes to these failures and propose a suitable stabilisation measure for both cases? &UTM M M B) It is a comm on practice to install shotcrete and wire mesh together. For an unstable slope face, why such practice is highly recommended. What is the purpose of wire mesh in shotcrete installation?

Structural Analysis

6th Edition

ISBN:9781337630931

Author:KASSIMALI, Aslam.

Publisher:KASSIMALI, Aslam.

Chapter2: Loads On Structures

Section: Chapter Questions

Problem 1P

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5. Point load tests were carried out on two sedimentary rock speci- mens of 54 mm diameter (NX core), as shown the following figure The loads P and P, at failure are 6.28 kN and 4.71 kN, respectively. Find the point load strength index I(50) in the two directions and compute the point load strength anisotropy index la(50). ПР PL 30 mm TP₁ 60 mm TP₁
'2\ Answer T for true statements or F for false ones: 1. Intact rock: solid rock sample containing cracks on eye naked. 2. Rock Mass: contains rock samples and crack surfaces on eye naked. 3. The rock sample will break if the applied force is vertical and associated with shear. 4. Unit weight (y) = gm./cm³. 5. Void Ratio (e) = Vs/Vv. 6. In point load test if the rock is fresh, ot= 5 * I, (50) 7. Brazilian Test provides tensile strength values closer to reality than Point Load Test. 8. Schmidt Hammer Test gives direct values for strength. 9. As more the surface is rough its strength for slipping decreases. 10.Fracture Intercept is the measured distance between irregular fractures !!
Q3\ Fill in the blanks with appropriate items: 1. Static force classified according to action into: 2. Physical properties of rocks are controlled by: 3. Strength value is amount of stress at -- 4. Point- Load Index (Is) = ----- 5. Point-load index for sample of 50 mm Diameter = 6. In point load test: Average ot= 7. Shear strength of intact rocks determined by 8. Deformation parameters are ---- 9. The friction strength formula of a discontinuity surface is: 10.At mountainous areas, RQD can be computed by equation: and --------and ------ Test. and --
The internal friction angle of structural plane is 15, and the cohesion is 10 MPa. The inclination angle of the structural plane is 45. The internal friction angle of intact rock is 30°, and the cohesion is 15 MPa. If the conventional triaxial loading stress path is adopted and the confining pressure is 15 MPa, what is the first principal stress when the rock mass is destroyed? What is the form of destruction? Please explain and calculate according to the stress path of conventional triaxial loading.
7. Shear strength of intact rocks determined by 8. Deformation parameters Test. are and
The intact rock that follows the Mohr–Coulomb failure criterion has c = 15 MPa and ϕ = 27°. Estimate the uniaxial compres sive strength σc, the uniaxial tensile strength σt and the Brazilian indirect tensile strength σ′ t . Give an estimate of the point load strength index Is(50) and suggest a realistic range for the Young’s modulus E.
10 - During unconfined compression test on 5 cm diameter intact rock sample the force at failure P=19.63 KN ,The rock strength is a) 10 MPa b) 3.8 MPa 12 MPa 0040693 d) 0.8 MPa
i. The following information is collected from rock coring process in which the total core advance was 65 cm. Core Recovery (cm) 20 7 Calculate: 11. a) The total core recovery b) The core recovery ratio c) The rock quality designation d) State the rock mass quality 6 10 16 A shear vane of length 150 mm and diameter 50 mm was used to measure the shear strength of saturated clay. The torque required at failure of the clay was 50 N-m. a) Assuming a triangular stress distribution along the vane ends, estimate the shear strength of the clay in kPa. b) On this clay, how deep can excavation advance without lateral support? Assume y= 18 kN/m³.
50 MPa Oc ON tan ф 20 + + -20 MPa 50 MPа 100 MPа O = 90 –20 -50 MPа
Figure 3 shows the stresses at failure for a point in a soil mass. Note A.U. (a) Draw the Mohr Circle for this point. (b) Determine the Pole Location. (c) Determine 01 and 03. (d) If the soil cohesion, c = 1.0, what is the friction angle of the soil, o? (e) Determine Tƒƒ and off. (f) What are the orientation of the failure planes, cr? 2 3 5 20° 51°
The stresses on a failure plane in a drained test on a cohesionless soil are as given below: Normal stress, o = 100 kN/m2, Shear stress = 57.73 kN/m2 The failure plane makes an angle of B with the minor principle plane. The value of B will be
50 MPa Oc ON tan ф 20 + + -20 MPa 50 MPа 100 MPа O = 90 –20 -50 MPа