Two CU triaxial tests are performed on a clay specimen. At failure, the results are: Test 1: σ3 = 30 kPa, P = 0.45 kN, Area of specimen = 0.01 m2 , u = 10 kPa Test 2: σ3 = 60 kPa, P = 0.70 kN, Area of specimen = 0.01 m2 , u = 20 kPa a) Find σ1, σ3, σ'1, and σ'3 at failure for both tests. b) Draw the effective stress Mohr's circle for both tests and draw the Mohr-Coulomb failure envelope for the clay. What are ' and c' for the clay? Write the equation for the MohrCoulomb failure envelope.

Determine the time of the day and month of the year at which the peak sensible cooling load occurs for a top floor, north-eastern corner room of an office building in durban for the following conditions: floor area: 8 x 8 x 3 m east and north walls: 115 mm face brick (outside), 20 mm air space, 115 mm ordinary brick (inside) with 15 mm plaster roof construction: suspended plasterboard ceiling, 450 mm air space, 150 mm concrete, 75mm screed, waterproofing no heat transfer across other surfaces window area 3x 1,5 m high in north wall only. ordinary glass with venetian blinds. lights and occupants : from 07: 00 to 18: 00 average light density: 25 w/m2 number of occupants : 5 seated, light office work room temperature 24°c