A 20 m thick clay layer is sandwiched between a silty sand layer and a gravelly sand layer. The layer experiences 30 mm settlement in 2 years. Given : 2 U for Us 60% TO Tv 4 100, %3D 1.784-0.933log,o (100 - U) for U> 60% where Ty is the time factor an U is the degree of consolidation in % If the coefficient of consolidation of the layer is 0.003 cm2/s, the deposit will experience a total o 50 mm settlement in the next years.

A 20 m thick clay layer is sandwiched between a silty sand layer and a gravelly sand layer. The layer experiences 30 mm settlement in 2 years. Given : 2 U for Us 60% TO Tv 4 100, %3D 1.784-0.933log,o (100 - U) for U> 60% where Ty is the time factor an U is the degree of consolidation in % If the coefficient of consolidation of the layer is 0.003 cm2/s, the deposit will experience a total o 50 mm settlement in the next years.

Fundamentals of Geotechnical Engineering (MindTap Course List)

5th Edition

ISBN:9781305635180

Author:Braja M. Das, Nagaratnam Sivakugan

Publisher:Braja M. Das, Nagaratnam Sivakugan

Chapter11: Ground Improvement

Section: Chapter Questions

Problem 11.9P

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2. For a certain soil profile, a uniformly distributed load, ΔP = 50kPa, is applied at the ground surface. Assume CS = 0.20CC. Take e = 0.95, LL = 50, height of clay layer = 8m and PO = 136.9kPa. Determine the settlement of the clay layer caused by primary consolidation if:a. The clay is normally consolidated. b. The preconsolidated pressure PC is 210kPa. c. The preconsolidation pressure PC = 150kPa.
The profile at a site consists of 5m of sand overlying 10m 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 19kN/m3 and that of the clay is 18kN/m3. The Cv of the clay is estimated to be 5x 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 200kPa 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 50kPa larger than the vertical effective stress that existed before the fill was placed?
A normally consolidated clay layer, 4m thick, has the following properties:Initial void ration, eo = 0.65Compression Index, Cc = 0.20Average effective pressure, σ’o = 100 kPaExpected pressure increase due to loading on ground surface = 30 kPaSecondary compression index, Cα = 0.02Time for completion of primary settlement = 1.5 yearsWhat is the total settlement of the clay layer five years after the completion of primary consolidation settlement?
Finding the expanded depth of the uniform mediumFilter medium sand grains (0.4mm in diameter)Ψ= 0.85specific gravity= 2.65depth of the bed=0.67mporosity=0.4T=20 Cμ= 1.002 .10-3N.s / m2ρw=998 .2 kg / m3 Determine the required backwash velocity to expand the bed to a porosity of 0.7.
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?
The soil profile at a site consists of a 2.0 m thick sand layerat the top, underlain by a 3.0 m thick clay layer. The watertable lies at a depth of 1.0 m below the ground level. Thebulk and saturated unit weights of the sand are 16.0 kN/m3and 19.0 kN/m3, respectively. The properties of the clay are:water content = 45.0%, specific gravity of the soil grains =2.70, compression index = 0.65, swelling index = 0.08, andoverconsolidation ratio = 1.5.a. The ground level is raised by placing a 1.5 m high compactedfill with unit weight of 20.0 kN/m3. What is theconsolidation settlement?b. When the consolidation due to the fill is completed,it is proposed to construct a warehouse imposing a uniform pressure of 40.0 kN/m2. What would be theconsolidation settlement due to the construction of thewarehouse?
A 2-meter clay layer (e=0.89, Gs=2.55, Cc=0.325) is overlain with 2 meter thick sand layer (e=0.82 G=2.63). the water table is at the interface of the sand and clay layer. if a 2-meter thick land fill (y=17.15kN/m^3) 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.
A uniform loading of 150kPa is applied at a 28 m Χ 28 m area. Please calculate the consolidation settlement of the clay layer used the middle of the clay layer to estimate the stress increment with the influence factor method). Cc = 0.4, Cs = 0.04, preconsolidation stress is 150 kPa and unit weight of water is 10 kN/m3. What is the settlement at the corner and center of the loading? What is the differential settlement between the corner and the center?
Use unit weight of water = 10kN/m3 in the following questions. A soil profile is shown in Figure Q2(c). If a uniform distributed load of 50 kN/m2 is applied at the ground surface, compute the average settlement of the clay layer caused by primary consolidation if; i)Determine the existing overburden effective stress at mid of clay layer ii) Settlement in clay if, the clay is normally consolidated, given Cc = 0.0085(LL-10) iii) Settlement in clay if, the preconsolidation pressure, pc’=200 kN/m2, given Cr=1/5Cc. Use Cc obtained in part (ii).
The sand layer shown is 2.5m thick. Beneath the sand layer is a 1.8m thick clay layer, underneath the clay layer is a solid rock. Water table is at depth of 0.9 m below the ground surface. SAND: Ymoist= 23KN/m3 ; Ysat= 21KN/m3 CLAY: Ysat= 23 KN/m3 ; LL= 42% e=0.7 A.) Compute the overburden pressure at mid-clay layer. B.) Find the maximum surface pressure without exceeding a 139.5mm settlement in clay layer if it is assumed to be normally consolidated. C.) If surface pressure is 70kpa and pre-consolidation pressure is 80kpa, find the settlement in clay layer.
A soft to very soft silty clay layer 3 m thick exists between a layer of permeable clayey silty sand at top and a nearlyimpermeable layer of stiff silty clay at bottom. Oedometer tests were carried out on a sample of the soft clay 19mmthick. From the plot of ΔH versus log time, the value of time t100 (the time at 100% primary consolidation) was100 min. From the graph of e versus log σ' the compression index Cc was 0.32 and the void ratio ep at the end of theprimary consolidation was 0.72. Estimate the secondary compression of the silty clay layer that would occur fromtime of completion of the primary consolidation to 30 years of the load application in the field.
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