Instructions

For the following questions answer them individually

Question 71

A square footing $$2m \times 2m$$ is built in a homogenous bed of sand of density $$\frac{1.9t}{m^{3}}$$ and having an angle of shearing resistance of $$38^\circ$$ The depth of base of footing is 0.8m below the ground surface. What is the safe load according to Terzaghi analysis which can be carried by the footing with a factor of safety of 3 against complete shear

failure? Assume $$\psi=38^\circ$$; $$N_{q}=65$$,$$N_{r}=80$$

Question 72

An elastic medium carries at its surface a uniform load of 10 $$\frac{t}{m^{2}}$$ ( $$\approx$$ 100 Kpa) covering a rectangular area of $$4m \times 3m $$.Find the vertical pressure at a depth of 5m below the center and corner of the loaded area. Assume influence factor of equal Quadrantis 0.0474 and influence factor for the point located at the corners of loaded area is 0.1247

Question 73

A retaining wall, 4.5m high has a smooth vertical back. The back fill has a horizontal surface in level with top of the wall. There is a uniformly distributed surcharge load of

$$\frac{2t}{m^{2}}$$ intensity over the back fill. The density of the soil is $$\frac{1.9t}{m^{3}}$$,its angle of shearing resistance is $$30^\circ$$ and cohesion is zero. Determine the magnitude of the total active pressure per metre length of wall.

Question 75

At two points โ1โ and โ2โ in a pipeline, the velocities of fluid are v and 3v respectively. Both points are at same elevation. The flow can be assumed to be incompressible,ย inviscid, steady and irrotational. The difference in pressure $$P_{1}$$ and $$P_{2}$$ at point 1 and 2 is

Question 76

The top width and depth of flow ina rectangular channel were measured as 4m and 1m respectively. The measured velocities on the center line at the water surface, 0.2m and 0.8m below the surface are 0.7 $$\frac{m}{s}$$,0.8 $$\frac{m}{s}$$,0.6 $$\frac{m}{s}$$ respectively. Using two point method of velocity measurement, the discharge $$(in \frac{m^{3}}{s})$$ in a channel is

Question 77

A rectangular open channel of width 5m is carrying a discharge of $$\frac{100 m^{3}}{s}$$. Froude number of flow is 0.8. The depth of flow in the channelis

Question 78

A concrete floor slab of 140 mm thick is reinforced by 16mm diasteel rods placed 38 mm above the lower face of the slab and spaced 150mm oncenter. The distance from the upper face of slab to steel is 100mm. The modulus of elasticity is 25 Gpa for concrete and 200 Gpa for steel. Knowing that a bending moment of 4.5KN-M is applied to each 0.30m width of slab, determine the maximum stress in the concrete and steel respectively

Question 79

The Poisson ratios of soil sample 1 & 2 are $$\mu_{1}$$ and $$\mu_{2}$$ respectively and the coefficient of earth pressure at rest for soil sample 1 and 2 are $$K_{1} and K_{2}$$ respectively.If $$\frac{\mu_{1}}{\mu_{2}}$$= 1.5 and $$\frac{1-\mu_{1}}{1-\mu_{2}} $$=0.875 then $$\frac{k_{1}}{k_{2}}$$ will be

Question 80

Maximum cement content, maximum water cement ratio and minimum grade of concrete with nominal weight of aggregate of 20 mm size for very severe exposure condition as per IS456-2000are respectively