What Overconsolidation ratio tells us?
The overconsolidation ratio (OCR) is a qualitative indicator of this densification or stiffening of the soil, and it is defined as the ratio of the maximum overburden stress ever experienced by the soil (i.e., with the ice sheet on top) to the present overburden stress (i.e., without the ice sheet).
What is Overconsolidation in soils?
The soil which had its load removed is considered to be “overconsolidated”. This is the case for soils that have previously had glaciers on them. The highest stress that it has been subjected to is termed the “preconsolidation stress”.
What causes Overconsolidation?
Overconsolidation can occur in clays due to reasons such as; Self-weight of the soil which has eroded. Weight of continental ice sheet which has melted. Desiccation of layers close to the surface.
What does normally consolidated mean?
Normally consolidated clays are these that are currently experiencing the maximum vertical overburden effective pressure they have ever experienced in their history. ➢ Over consolidated clays have experienced a higher overburden stress in the past. ➢
Can the Overconsolidation ratio be smaller than 1?
The overconsolidation ratio, OCR, is the ratio of σp to σ o, and nu- merically represents the state of consolidation: an OCR equal to 1 is a normally consolidated sediment, an OCR greater than 1 shows over- consolidation, and an OCR less than 1 shows underconsolidation.
How do you determine if clay is normally consolidated or Overconsolidated?
Overconsolidation. If the current state of soil is on the normal compression line it is said to be normally consolidated. If the soil is unloaded it becomes overconsolidated.
What is compressibility of soil?
Soil compressibility is the ease with which a soil decreases in volume when subjected to a mechanical load. The process that describes the decrease in soil volume (soil densification) under an externally applied load is defined as compression.
What is consolidation stress?
The process of gradual transfer of stress from the pore pressure to effective stress with the associated volume change is referred to as consolidation.
What does Overconsolidated clay mean?
over-consolidated clay Clay that has been more compacted than would be expected from the existing overburden, e.g. it has been subjected to pressure from overburden that has subsequently been removed by erosion. Compare NORMALLY CONSOLIDATED CLAY. A Dictionary of Earth Sciences. “over-consolidated clay .”
What is consolidation test?
Consolidation test is used to determine the rate and magnitude of soil consolidation when the soil is restrained laterally and loaded axially. The Consolidation test is also referred to as Standard Oedometer test or One-dimensional compression test.
What are Overconsolidated clays?
What is cohesive soil?
Cohesive soil means clay (fine grained soil), or soil with a high clay content, which has cohesive strength. Cohesive soil does not crumble, can be excavated with vertical sideslopes, and is plastic when moist. Cohesive soil is hard to break up when dry, and exhibits significant cohesion when submerged.