Q1: When the seepage pressure becomes equal to the pressure due to submerged weight of a soil, the effective pressure is reduced to zero and the soil particles have a tendency to move up in the direction of flow. This phenomenon is generally known

ANS:D - all the above.

1. Quick condition: In geotechnical engineering, the term "quick condition" refers to a state in which the effective pressure in a soil mass becomes zero due to the balance of seepage pressure and submerged weight. This condition can occur in saturated soils, particularly in fine-grained, cohesionless soils like sands and silts, when they are subjected to upward flow of water. As the upward seepage pressure exceeds the weight of the soil particles, the effective pressure becomes zero, leading to loss of shear strength and potential for instability. Soil particles may start floating and behave like a fluid, which can be hazardous, especially for construction and excavation projects.
2. Quicksand: Quicksand is a colloquial term used to describe a specific type of quick condition in natural settings. It typically occurs in loose, saturated sand deposits, where upward flow of water reduces the effective stress between grains, causing them to lose shear strength and behave like a fluid. Quicksand can pose significant risks to individuals and equipment, as people or objects may sink rapidly into the sand due to the loss of support from the surrounding soil.