An aquifer is overlain by 15 m of jointed rock. The density of the rock is 2500 kg/m. The density and compressibility of water are 1000 kg/m and 4.5 x 10-10 m2/N (Pa), respectively. Illustrate the system Calculate the total stress acting on the top of the aquifer. If the pressure head in the aquifer is 22 m, calculate the effective stress in the aquifer. If the aquifer is pumped and the hydraulic head at some point reduced by 5 m, what will be the resulting changes the pressure head, the fluid pressure, the effective stress, and the total stress? If the compressibility of the aquifer is 5 x 10° m-/N and its thickness is 7 m, how much compaction will the aquifer undergo during the head reduction in part (c)?

An aquifer is overlain by 15 m of jointed rock. The density of the rock is 2500 kg/m. The density and compressibility of water are 1000 kg/m and 4.5 x 10-10 m2/N (Pa), respectively. Illustrate the system Calculate the total stress acting on the top of the aquifer. If the pressure head in the aquifer is 22 m, calculate the effective stress in the aquifer. If the aquifer is pumped and the hydraulic head at some point reduced by 5 m, what will be the resulting changes the pressure head, the fluid pressure, the effective stress, and the total stress? If the compressibility of the aquifer is 5 x 10° m-/N and its thickness is 7 m, how much compaction will the aquifer undergo during the head reduction in part (c)?

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 10.19P

See similar textbooks

Similar questions

Q1 A 25 m thick layer of clay is underlain by a layer of silt, as shown in the Figure. 1. Determine the effective stress at point A when Z=3 m. 2. Determine the effective stress at point B when h=3 m. 3. By changing h and Z, would you expect that the effective stresses at A and B can have the same value? WIZ 1² W.T 12 m B Clay e=0.6, G.-2.69 Clay w=30% Silt w=50%, G, 2.70
The soil profile shown consists of dry sand (4-m thick) which overlies a layer of clay (3-m thick). Ground water table is located at the interface of the sand and clay. a. If the water table rises to the top of the ground surface, what is the change in the effective stress (in kPa) at the bottom of the clay layer? Round off to two decimal places. (ANSWER: 26.336) b. Compute the effective stress at the bottom of the clay layer in kPa. Round off to three decimal places (ANSWER: 97.686) c. How many meters must the ground water table rise to decrease the effective stress by 14 kPa, at the bottom of the clay layer? Round off to two decimal places (ANSWER: 2.13)
1. Calculate total stress, pore-water pressure and effective stress at location A. If the water table rises to ground surface level what will be the increase or decrease in effective stress at location A. Ground Surface 4 m 5m 6 m 3 = 1600 kg/m P₁= 3 P= 1750 kg/m sat 3 PF 800 kg/m sub A Sand Silty Sand Silty Clay
3. The upward flow of water through a layer of sand in the tank shown in figure has the following properties: e =0.50, G-2.67. Determine the following: a) Effective stress at point A b) Effective stress at point B c) Upward seepage force per unit volume of soil 0.8m 3.5m Supply of Water 0.5m A B 1.9m
Evaluate the figure shown and solve what is being asked in the problem with the following given: e = 0.42 G = 2.8 H1 = 0.3 m H2 = 3.3 m h1 = 0.9 m z = 1.2 m a. What is the saturated unit weight of sand in kN/m³? b. Calculate the total stress at point C in kPa. c. Calculate the effective stress at point B in kPa.
A 5 × 10 m area is loaded with 100 kPa as shown in the figure. a) Find the stress at a depth of 5 m below point A b) Find the stress at the same point if the right half of the 5 × 10 m area is loaded with an additional 100 kPa. (Ans: a) 0.97 kPa, b) 1.15 kPa
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)
Using equation 6.14, determine the vertical stress (Aoz) increase below the center of the loaded area at depths z = 2, 4, 6, 8, and 10 m. 6.35m O -2.4 m 3.35m I A B 1.2 m q=225 kN/m² 18m→ C B
(b) A layer of saturated clay with 4 m thick is overlain by sand with thickness of 5 m deep, the water table being 3 m below the surface, as shown in Figure BELOW. The saturated unit weights of the clay and sand are 19 and 20 kN/m³, respectively; above the water table the (dry) unit weight of the sand is 17 kN/m². 3 m 5 m Sand Clay 4 m (i) Plot the diagrams of total vertical stress, pore water pressure and effective vertical stress against depth (ii) calculate the total stress, pore water pressure, and effective stress at points A, B and C.
b. Consider the downward flow of water through a layer of sand in a tank shown below. For the sand, the following properties are given: e = 0. 48 , G. S = 2.70 . Calculate the effective stress at A. 0.6 m 1.5 m 0.8 m Ao 2.5 m Sand Outflow
Given: H₁ = 1.10 m, H₂ = 2.20 m, h = 1.30 m, void ratio of sand e = 0.62, specific gravity of soil solids Gs = 2.72, area of the tank = 0.5 m², and hydraulic conductivity of sand = 0.1 cm/sec. a. What is the effective stress at C if z = 1.23 m? b. What should be the value of h to cause boiling? Outflow Inflow H₂ Valve (open)
Consider a clay layer with a thickness of 36 meters and a Ccɛ = 0.2 and a Crɛ = 0.02. A circular tank 20 meters in diameter transfers a surface stress of qo = 225 kPa. The clay is divided into 12 sublayers of equal thickness. The initial effective stress σ'vo, preconsolidation pressure σ'p, and stress caused by the circular tank Δσv are given by the provided equations. In these equations, z is the depth in meters; r is the radius of the loaded area; and σ'vo, σ'p, and Δσv are in kPa. Calculate the contribution to the total consolidation settlement of the sublayers with midlayer depth of 7.5 meters and 28.5 meters.