Definitions and Properties of Soils · Geotechnical Engineering · GATE CE
Marks 1
The contact pressure distribution shown in the figure belongs to a
Which one of the following saturated fine-grained soils can attain a negative Skempton’s pore pressure coefficient (A)?
A reinforced concrete pile of 10 m length and 0.7 m diameter is embedded in a saturated pure clay with unit cohesion of 50 kPa. If the adhesion factor is 0.5, the net ultimate uplift pullout capacity (in kN) of the pile is ____________ (rounded off to the nearest integer).
A 2 m wide strip footing is founded at a depth of 1.5 m below the ground level in a homogeneous pure clay bed. The clay bed has unit cohesion of 40 kPa. Due to seasonal fluctuations of water table from peak summer to peak monsoon period, the net ultimate bearing capacity of the footing, as per Terzaghi’s theory, will
An embankment is constructed with soil by maintaining the degree of saturation as 75% during compaction. The specific gravity of soil is 2.68 and the moisture content is 17% during compaction. Consider the unit weight of water as 10 kN/m$^3$. The dry unit weight (in kN/m$^3$) of the compacted soil is _________________ (rounded off to 2 decimal places).
Marks 2
Consider the statements P and Q related to the analysis/design of retaining walls.
P: When a rough retaining wall moves toward the backfill, the wall friction force/resistance mobilizes in upward direction along the wall.
Q: Most of the earth pressure theories calculate the earth pressure due to surcharge by neglecting the actual distribution of stresses due to surcharge.
Which one of the following options is CORRECT?
Consider the statements P, Q, and R.
P: Compacted fine-grained soils with flocculated structure have isotropic permeability.
Q: Phreatic surface/line is the line along which the pore water pressure is always maximum.
R: The piping phenomenon occurring below the dam foundation is typically known as blowout piping.
Which of the following option(s) is/are CORRECT?
A homogeneous earth dam has a maximum water head difference of 15 m between the upstream and downstream sides. A flownet was drawn with the number of potential drops as 10 and the average length of the element as 3 m. Specific gravity of the soil is 2.65. For a factor of safety of 2.0 against piping failure, void ratio of the soil is __________ (rounded off to 2 decimal places).
The in-situ percentage of voids of a sand deposit is 50%. The maximum and minimum densities of sand determined from the laboratory tests are 1.8 g/cm3 and 1.3 g/cm3, respectively. Assume the specific gravity of sand as 2.7.
The relative density index of the in-situ sand is ______________ (rounded off to 2 decimal places).
A drained triaxial test was conducted on a saturated sand specimen using a stress-path triaxial testing system. The specimen failed when the axial stress reached a value of 100 kN/m2 from an initial confining pressure of 300 kN/m2.
The angle of shearing plane (in degrees) with respect to horizontal is ______________ (rounded off to the nearest integer).
A vertical smooth rigid retaining wall is supporting horizontal ground with dry cohesionless backfill having a friction angle of 30°. The inclinations of failure planes with respect to the major principal plane for Rankine’s active and passive earth pressure conditions, respectively, are
Which of the following statement(s) is/are CORRECT?
The total primary consolidation settlement ($S_c$) of a building constructed on a 10 m thick saturated clay layer is estimated to be 50 mm. After 300 days of the construction of the building, primary consolidation settlement was reported as 10 mm. The additional time (in days) required to achieve 50% of $S_c$ will be ________________ (rounded off to the nearest integer).
An infinite slope is made up of cohesionless soil with seepage parallel to and up to the sloping surface. The angle of slope is 30° with respect to the horizontal ground surface. The unit weights of the saturated soil and water are 20 kN/m3 and 10 kN/m3, respectively.
The minimum angle of shearing resistance of the soil (in degrees) for the critically stable condition of the slope is ________________ (rounded off to the nearest integer).
A soil sample was consolidated at a cell pressure of 20 kPa and a back pressure of 10 kPa for 24 hours during a consolidated undrained (CU) triaxial test. The cell pressure was increased to 30 kPa on the next day and it resulted in the development of pore water pressure of 1 kPa. The soil sample failed when the axial stress was gradually increased to 50 kPa. The pore water pressure at failure was recorded as 21 kPa. The value of Skempton's pore pressure parameter B for the soil sample is ________________ (rounded off to 2 decimal places).