Principles of Foundation Engineering (MindTap Course List)
9th Edition
ISBN: 9781337705028
Author: Braja M. Das, Nagaratnam Sivakugan
Publisher: Cengage Learning
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Chapter 2, Problem 2.10P
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?
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A ground profile consists of 2m silty sand underlain by 3m of clay. The ground water table is 3m below the ground surface. The sand has a unit weight of 14kN/cum. The clay has a unit weight of 16kN/cum above the water table and 20kN/cum below the water table.
Determine the Total stress at the surface of the water table (kPa).
Determine the effective stress at the bottom of the clay layer (kPa).
Determine the effective stress 1m from the bottom of the clay layer (kPa).
Please answer this asap. For upvote. Thank you very much
Problem 1
A ground profile consists of 2 m of silty sand underlain by 3 m of clay. The ground water table is 3 m below the ground surface. The sand has a unit weight of 14 kN/m3. The clay has unit weight of 16 kN/m3 above the water table and 20 kN/m3 below the water table.
a. Determine the total stress at bottom of the clay
b. Determine the pore water pressure at the bottom of the clay
c. Determine the effective stress at the bottom of the clay
Problem 2
50 ft thick sand is underlain by 25 ft clay. The ground water table, initially at the ground surface, was lowered to a depth of 25 ft below the ground. After such lowering, the degree of saturation of the sand above water table was lowered to 20%. Saturated and dry unit weight of sand are 135 pcf and 116 pcf respectively. The saturated unit weight of clay is 120 pcf.
a. What is the vertical effective pressure at the midheight of the clay layer before lowering of the water table in psf?
b. What is the vertical effective pressure at the…
A granular soil deposit is 4 m. thick and underlying it is a clay having a
thickness of 5 m. There is a water table at the interface of the soil and the
clay. Unit weight of sand is 15.6 kN/m and saturated unit weight of clay is
17.8 kN/m.
O What is the effective stress at the bottom of the clay?
O If the water table rises to the level of the soil surface, what is the effective
stress at the bottom of the clay?
O f the water is 3 m. above the soil surface, what is the effective stress at the
bottom of the clay?
Chapter 2 Solutions
Principles of Foundation Engineering (MindTap Course List)
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, civil-engineering and related others by exploring similar questions and additional content below.Similar questions
- A ground profile consists of 2.0 meters silty sand underlain by 3.0 meters of clay. The ground water table is 3.0 meters below the ground surface. The sand has a unit weight of 14 kN/cu.meter. The clay has a unit weight of 16 kN/cu.meter above the water table and 20 kN/cu.meter below the water table. Determine the total soil stress at the bottom of the clay layer.arrow_forwardA 10 m thick sand layer is underlain by 8 m thick clay layer. The groundwater is found to be at 3 m below the surface at the present time. In the Past (long time ago) the ground water table was at 6 m below the ground surface. The sand unit weight, ymoist=18 kN/m³ and the clay saturated density y«at = 17 kN/m³. Required: A) Total stress, pore pressure and effective stress at points A, B and C in Both Cases? B) Calculate the over consolidation ratio (OCR) at the midpoint of the clay layer? A Present groundwater level Sand Y= 18 kN/m3 10m 3m Current B Case 4m A Clay y= 17 kN/m3 C 4m A Sand Past groundwater level Tem 10m Y= 18 KN/m3 Previous B Case 4 m A Clay y= 17KN/m Carrow_forwardsand layer 5m thick is underlain with a thick layer of clay. the sand has a void ratio of 0.52 and specific gravity 2.64. The clay has a water content of 42% and specific gravity of 2.64. The ground water table is located 3 m below the ground surface. The sand above the water table is 30% saturated. a.) Determine the unit weight of the clay b.) Determine the total stress at a depth of 10 m below the ground surface. c.) Determine the effective stress at a depth of 10m below the ground surface.arrow_forward
- 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?arrow_forwardA layer of saturated clay 5 m thick is overlain by 7 m thick sand layer. The water table lies at junction of sand and clay layers and soil is saturated by capillary action upto 4 m above the junction. The saturated unit weight of sand and clay are 19 kN/m³ and 16 kN/m3 respectively and bulk unit weight of sand is 18 kN/m³. The effective stress just above the new water level is 54 kN/m2. Correct Option The effective stress at the junction of clay layer and sand layer is 130 kN/m2. Correct Option The effective stress just below the initial water level is 93.24 kN/m². The pore water pressure at the junction of sand and clay layer is 0 kN/m2. Correct Optionarrow_forwardneed fast please A soil profile consists of sand (6-m thick) which overlies a layer of clay (6-m thick). Ground water table is located at the interface of the sand and clay. The effective stress at the bottom of the clay layer was determined. 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? For sand layer: Void Ratio = 0.88, Specific gravity = 2.75, Degree of Saturation = 0.79 For clay layer: Void Ratio = 0.99, Specific gravity = 2.86 Round off to two decimal places.arrow_forward
- A uniform soil deposit has a dry unit weight of 15.6 kN/m³ and a saturated unit weight of 17.2 kN/m³. The groundwater table is at a distance of 4 m below the ground surface. Point A is at a depth of 6 m below the ground surface. If the water table rises by 3.5 m, determine the change in effective stress at A. Indicate if it is maintained, increased or decreased.arrow_forwardA 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.arrow_forwardA decision has been made to consolidate the clay before the site development by applying an additional sand layer 1m thick (γ = 15kN/m^3) at the top.• What is the effective stress in the mid-layer of clay before and after the surcharge has been applied?• If the soil profile was dewatered by 1.8m while the surcharge is applied, what is the effective stress in the mid -layer of clay instead?• If a point load of 200kN was applied instead of the surcharge (and no dewatering occurred), what is the effective stress at a point 3.4m away and 1.8m deep into the profile?Final answer(s) should be in 3 decimal places.arrow_forward
- A 1.5m thick layer of clay is located between 2 layers of sand. At the center of the clay layer, the total vertical stress is of 200 kPa and the pore pressure is 100 kPa. The increase in vertical stress caused by the construction of a structure, in the center of the layer will be 100 kPa. Assuming a saturated soil, Cr = 0.05, Cc = 0.3 and e = 0.9. Estimate the primary settlement of the clay, considered. - Normally consolidated soil - Pre-consolidated soil (OCR=2) - Pre-consolidated soil (OCR=1.5)arrow_forwardA soil profile of sand (7m thick) which overlies a layer of clay (8m thick). Ground water table is located at the interface of the sand and clay. The effective stress at the bottom of the clay layer was determined. If the water table rises to the top of the ground surface, what is the change in effective stress (in kpa) at the bottom of the layer? for sand layer: void ratio = 0.81, specific gravity = 2.74, degree of saturation = 0.65 for the clay layer: void ratio = 0.85, specific gravity = 2.85arrow_forwardQ.1 Top layer of a soil deposit consists of a clay layer of 4 m thickness overlaying a very thick layer of sand. Even though the water table is at middle of clay layer, the clay soil above the water table is saturated. The water content of clay strata is 30% while that of sand strata is 26%. If the specific gravity of clay and sand are 2.72 and 2.64 respectively. Calculate the total stress, pore water pressure and effective stress at a depth of 8 m from ground surface.arrow_forward
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