The soil profile at a site consists of 10 m of gravelly sandunderlain by a soft clay layer. The water table lies 1 m belowthe ground level. The moist and saturated unit weights of thegravelly sand are 17.0 kN/m3 and 20.0 kN/m3, respectively.Due to some ongoing construction work, it is proposed tolower the water table to 3 m below the ground level. Whatwill be the change in the effective stress on top of the softclay layer?

The soil profile at a site consists of 10 m of gravelly sandunderlain by a soft clay layer. The water table lies 1 m belowthe ground level. The moist and saturated unit weights of thegravelly sand are 17.0 kN/m3 and 20.0 kN/m3, respectively.Due to some ongoing construction work, it is proposed tolower the water table to 3 m below the ground level. Whatwill be the change in the effective stress on top of the softclay layer?

Fundamentals of Geotechnical Engineering (MindTap Course List)

5th Edition

ISBN:9781305635180

Author:Braja M. Das, Nagaratnam Sivakugan

Publisher:Braja M. Das, Nagaratnam Sivakugan

Chapter8: Stresses In A Soil Mass

Section: Chapter Questions

Problem 8.10P: The soil profile at a site consists of 10 m of gravelly sand underlain by a soft clay layer. The...

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The soil profile at a site consists of 10 m of gravelly sand underlain by a soft clay layer. The water table lies 1 m below the ground level. The moist and saturated unit weights of the gravelly sand are 17.0 kN/m3 and 20.0 kN/m3, respectively. Due to some ongoing construction work, it is proposed to lower the water table to 3 m below the ground level. What will be the change in the effective stress on top of the soft clay layer?
A soil profile, under surcharge load of 25 kN/m2 at ground level, consists of 6m sand and 3m clay layer. Ground water table is 2m below sand layer. Dry unit weight and saturated unit weight of sand is 15.80kN/m3 and 16.90kN/m3 respectively. Clay layer, Gs=2.67 and saturated unit weight is 18.80 kN/m3. Determine a)Increase in stress at the mid layer of clay b) With dewatering 2m, what is the stress increase at the mid layer of clay c) How much must the water level be lowered to me more effective than the surcharged load?
A rectangular footing (4.14 x 4.43 m) is placed 1.38 m below the ground surface. The soil arrangement is composed of sand (ground) for the first 6.29 m and followed by clay for the next 5.94 m. The force acting on the footing is 10581 kN. Determine the resulting stress increase at the midheight of the consolidating layer in kPa. Assume 2V:1H pressure diagram. Unit weight of sand = 16.8 kn/m3. Unit weight of clay = 18.4 kn/m3
A rectangular footing (4.89 x 4.38 m.) is placed 1.21 m. below the ground surface. The soil arrangement is composed of sand (ground) for the first 6.52 meters and followed by clay for the next 6.98 meters. The force acting on the footing is 10,293 kN. Determine the resulting stress increase at the midheight of the consolidating layer in kPa. Assume a 2V:1H pressure diagram. Unit weight of sand = 16.1 kN/m3. Unit weight of clay = 18.7 kN/m3. Use stored value. Answer in five decimal places.
A site is underlain by a soil that has a unit weight of 18.7 kN/m3 above the groundwater table and 19.9 kN/m3 below. The groundwater table is located at a depth of 3.5 m below the groundsurface. Compute the total vertical stress, pore water pressure, and effective vertical stress atthe following depths below the ground surface:a. 2.2 mb. 4.0 mc. 6.0 m
The profile at a site consists of 5 m of sand overlying 10 m of compressible clay, which in turn overlies a dense sand. The water table is at the top of the profile. The total unit weight of the top sand is 19 kN/m3, and that of the clay is 18 kN/m3. The cv of the clay is estimated to be 5 x 10-3 cm2/sec. Initially the clay is normally consolidated. It is planned to place a temporary fill that will exert a vertical load of 200 kPa over the entire site. How long must the fill be in place so that, after it is removed, the maximum past pressure at every point in the clay is at least 50 kPa larger than the vertical effective stress that existed before the fill was placed?
A bed of sand 12 m thick is underlain by a compressible stratum of normally loaded clay, 6 m thick. Thewater table is at a depth of 5 m below the ground level. The unit weight of sand above and below watertable are 17.5 kN/m3 and 20.5 kN/m3 respectively.The clay has a natural water content of 40% and LL of 45% and Gs=2.75. Estimate the probable finalsettlement if the average increment in pressure due to foundation is 100 kN/m2
Question 6 A 3-meter clay layer (e = 0.86, Gs = 2.69, Cc = 0.304) is overlain with 2-meter-thick sand layer (e = 0.77, G = 2.83). The water table is at the interface of the sand and clay layer. If a 2-meter-thick land fill (γ = 17.53 kN/m3) is placed over the existing ground surface, compute the consolidation settlement (in mm.) of the clay layer. Hint: Use the land fill's resulting pressure on the ground surface as the stress increase. Round off to two decimal places.
A clay formation having a depth of 4 m. underlies a sand formation having a depth of 3 m. The dry unit weight of sand is 16.5 kN/m3 and the saturated unit weights of clay and sand are 20.4 kN/m3 and 19.6 kN/m3 respectively. The groundwater table is at the interface of the sand and clay. Compute the effective stress at the bottom of clay. Use 3 decimal places in MPa.
A 2-meter clay layer (e = 0.88, Gs = 2.67, Cc = 0.305) is overlain with 4-meter-thick sand layer (e = 0.82, G = 2.72). The water table is at the interface of the sand and clay layer. If a 2-meter-thick land fill (γ = 17.97 kN/m3) is placed over the existing ground surface, compute the consolidation settlement (in mm.) of the clay layer. Hint: Use the land fill's resulting pressure on the ground surface as the stress increase. Round off to two decimal places. Selected Answer: 60.25
A 2-meter clay layer (e = 0.88, Gs = 2.67, Cc = 0.305) is overlain with 4-meter-thick sand layer (e = 0.82, G = 2.72). The water table is at the interface of the sand and clay layer. If a 2-meter-thick land fill (γ = 17.97 kN/m3) is placed over the existing ground surface, compute the consolidation settlement (in mm.) of the clay layer. Hint: Use the land fill's resulting pressure on the ground surface as the stress increase. Round off to two decimal places.
A granular soil is subjected to a minor principal stress of 200 kN/m2. If the angle of internal friction is 30°, determine the inclination of the plane of failure with respect to the direction of the major principal stress. a.60 b.37.5 c.45 d.30 e.50