z (m) 0m 2 m 5 m 10 m H Alluvial Sand Soft Clay & A Embankment M C Dense Sandy Gravel Bedrock Ground Surface GWT Standpipe Manometer
Please help me in answering the following soil
In the attached image, the cross-sectional soil profile of a road construction site can be seen. The plan is to construct a road embankment of height H = 3 meters, base width B = 10 meters, and top width A = 4 meters using a granular fill with a bulk density of 21 kN/m3. The embankment is symmetric about its vertical centreline.
Here, the soil profile consists of the following (attached in image as well):
- 2-meter-thick alluvial sand layer (GS = 2.65; e = 0.47; ϕ′ = 32◦)
- Overlying a 3-meter-thick normally consolidated soft clay layer (GS = 2.75; w = 36.5%; ϕ′ = 20◦ Cc = 0.30; Ce = 0.05; mv = 5.6 × 10−4 m2/kN; k = 1.2 × 10−10 m/s)
- Underlain by 5-meter-thick deposit of dense sandy gravel (γsat = 20 kN/m3; ϕ′ = 35◦)
- At 10 meters depth, Impermeable bedrock is encountered.
- Here, ground surface is horizontal and groundwater table (GWT) is initially hydrostatic located at a depth of 2 meter below the ground surface.
- The alluvial sand layer above the GWT is completely dry.
(a) If all the soil layers are under-at-rest earth pressure conditions, how can I calculate and plot the profiles of effective vertical stress σ'v and effective horizontal stress σ'h with depth z from the ground surface down to the top of the bedrock prior to the construction of the embankment?
(b) A standpipe manometer is installed at point M located within the soft clay layer at depth z = 4 meters from the ground surface and is allowed to come to hydrostatic equilibrium with the GWT before the construction of the embankment. If there is instantaneous embankment construction,what will be the height h of the water level inside the manometer with reference to the GWT before and immediately after the construction of the embankment?.
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