A saturated compressible clay layer of thickness h is sandwiched between two sand ayers, as shown in the figure. Initially, the total vertical stress and pore water pressure at point P. which is located at the mid-depth of the clay layer were 150 kPa and 25 kPa. respectively. Construction of a building caused an additional total vertical stress of 100 kPa at P. When the vertical effective stress at P is 175 kPa. the percentage of consolidation n The clay layer at P is

A saturated compressible clay layer of thickness h is sandwiched between two sand ayers, as shown in the figure. Initially, the total vertical stress and pore water pressure at point P. which is located at the mid-depth of the clay layer were 150 kPa and 25 kPa. respectively. Construction of a building caused an additional total vertical stress of 100 kPa at P. When the vertical effective stress at P is 175 kPa. the percentage of consolidation n The clay layer at P is

Principles of Geotechnical Engineering (MindTap Course List)

9th Edition

ISBN:9781305970939

Author:Braja M. Das, Khaled Sobhan

Publisher:Braja M. Das, Khaled Sobhan

Chapter10: Stresses In A Soil Mass

Section: Chapter Questions

Problem 10.9P: For the same line loads given in Problem 10.8, determine the vertical stress increase, z, at a point...

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For a site, there is a layer of sand, 5.3m thick, that lies over a clay layer of 1.2m. The water table is 1.3m below the ground surface. The saturated unit weights of the sand and clay are 21.6 kN/m3 and 18.8 kN/m3, respectively. The unit weight of sand above the water table is 17.2 kN/m3. Determine the total vertical stress, porewater pressure and effective vertical stress at the bottom of each layer. Plot the values found in (a) against the depth below ground level. If the water table rises up to an elevation of 0.7 m above the ground level, what will the total vertical stress, pore water pressure and effective vertical stress at the bottom of the clay layer?
5. A thick layer of stiff saturated clay is underlain by a layer of sand under artesian pressure. A deep cut is made in the clay layer as shown in the attached figure. Determine: [2] a. The total stress at point A. b. The factor of safety against heaving at point A, if the effective stress is 12% of the total stress.
A soil profile consists of two layers of soil with clay layer underlying the sand layer. The sand layer has a unit weight of 20 kN/m^3 having a thickness of 4 m. and the unit weight of the 2.5m layer of clay is 18 kN/m^3. Compression index of the clay is 0.22 with a void ratio of 1.30. Compute the effective stress (kPa) at the mid height of clay. Calculate the final settlement of the clay layer (mm) due to an increase of pressure of 30 kPa at the mid-height of the clay. Calculate the settlement (mm) when the water table rises to the ground surface.
Consider a circularly loaded flexible area acting on the ground surface. The radius of the circular area is 20 ft and the uniformly distributed load is q = 1,000 lb/ft2. Calculate the vertical stress increase, Δσz, at a depth of 10 ft for a radius of 0 ft (immediately below the center of the circular area) and 20 ft (immediately below the edge of the circular area).
A soil profile is shown in Figure Q3(b)(i). The groundwater level is located on the ground surface. The sand layer is under artesian pressure where the excess pore water pressure is 40 kN/m^2. (i) Calculate the total vertical stress, pore water pressure and effective vertical stress at the base of each layer. (ii)Determine the increment of the effective stress at the base of sand layer if the 1.5m height fill will be imposed on the ground surface. Note that, the density of the fill material is 1750 kg/m^3. (iii) The excavation will be made in the clay layer for the basement construction. Evaluate the stability of the soil from boiling or quick condition. The depth of the excavation is shown in Figure Q3(b)(ii). (iv)Propose the maximum depth of cut that can be made to avoid boiling or quick condition.
The following figure is a layer of sand (γ s a t=130 lb/ft3 ) in a tank of water. If point C is located at the middle of the soil layer, what is the effective stress at point C: (a) when the valve is closed (there is no seepage) (b) when the valve is open (there is downward seepage)
A soil profile shown has a zone of capillary rise in the sand overlying the clay. In this zone, the average degree of saturation is 60% with a moist unit weight of 17.6 kN/cu.m.Compute the effective stress inside the capillary zone at a depth of 3.0 m below the ground surface. Compute the effective stress at a depth of 3.9 m below the ground. Compute the effective stress at C.
A layer of saturated clay 4m thick is overlain by sand 5m deep, the water table being 3m below the surface. The saturated unit weights of the clay and sand are 19 and 20 kN/m^3, respectively; above the water table the (dry) unit weight of the sand is 17 kN/m^3 . Determine the effective stress at mid-height of the clay layer in kPa. Round your answer to 2 decimal places.
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 saturated clay layer (300cm in thickness) was sitting upon the rock, its unit weight was = 20kN/m3, an oedometer test also found that Cc = 0.2, Cr = 0.04. The existing vertical effective stressin the field is 200 kPa. Construction will increase the vertical stress at the centre of the clay by = 600 kPa.a) Calculate the primary consolidation settlement of clay layer if it has been subjected toa load at OCR = 2.b) Assume spatial variation of pore pressure u with time t and depth z is onedimensional,and governed by:where Cv is a given constant, specify its boundary and initial condition, and try toillustrate the pore pressure change with time along its depth.
The water table in an 8 m thick silty sand deposit lies at a depth 3 m below the ground level. The entire soil above the water table is saturated by capillary water and the saturated unit weight is 18.8 kN/m^3 . Calculate the a) total vertical effective stress, b) the porewater pressure, and c) the vertical effective stress at 8 m below the ground level. Express answers in kPa rounded to the first decimal place.
A)Plot graphically all the vertical stresses, pore water and effective vertical stresses throughout the depth. B)How would the effective vertical stress value at the midpoint of the clay layer change if the groundwater level increased 2 m? (g = 10 m / s2)