Reference no: EM132418609

Question 1

Figure 2 shows the layout of a foundation for a building which transmits a uniform pressure of 11-10² kPa on the soil surface. Figure 3 shows the soil stratigraphy and Table 1 gives the soil properties.

a) Determine the stresses at point A which is directly below point C and at the midpoint of the sand stratum.

b) Determine the stresses at point B which is directly below point C and at the midpoint of the clay stratum.

c) Calculate the immediate settlement of the foundation at point C; the Young's modulus of the sand and clay are 4 MPa and 1 MPa
respectively.

Figure 2

Figure 3

Table 1

Soil layer	Dry Unit Weight  (kN/m3)	Saturated Unit Weight  (kN/m3)	Young's modulus (MPa)
Sand	16	19	4
Clay	18	20	1

Question 2

Table 3below lists data obtained from consolidated undrained triaxial tests on soft clay.

Table 3

Tests	Cell pressure   (kPa)	Deviator stress at failure (kPa)	Pore water pressure at failure (kPa)
1	211	118	110
2	411	240	220
3	611	352	320

Assuming the unit weight of water is equal to 10 kN/m³:

a) Draw the Mohr circle of effective stress.

b) Determine the shear strength parameters in terms of effective stress.

c) Plot the critical state line and determine the critical state parameter M.

Question 3

Figure 4 shows a square footing of dimensions 1 m x 1 m which supports a column load of 11.10²kN. The footing is founded at 1 m below the ground surface. The properties of the soil are given in Table 4. The clay is normally consolidated. The ground water table is 3 m below the ground surface and the unit weight of water is 9.81 kN/m³. Calculate the consolidation settlement of the clay layer that wil result from the column's load carried by the footing.

Figure 4

Table 4

Soil layer	Dry Weight kN/m3	Unit	Saturated Weight  kN/m3	Unit	Specific Gravity	Compression index (Cc)
Sand	16		19		2.6	-
Clay	18		20		2.8	0.27

Question 4

The gravity retaining wall shown in Figure 5 has a height of 7 m and a horizontal backfill of dry sand with a unit weight of 17.2 kN/m³ and an angle of friction of 41º. The retaining wall is cast in situ concrete with an angle of interface friction of 20º.

a) Calculate the magnitude of active and passive pressures upon a length of wall equal to 11 m using Rankine's method.

b) Plot the active pressure distribution with depth.

Figure 5