How does freezing and thawing contribute to creep?
Creep can be facilitated by freezing and thawing because, as shown in Figure 15.12, particles are lifted perpendicular to the surface by the growth of ice crystals within the soil, and then let down vertically by gravity when the ice melts. The same effect can be produced by frequent wetting and drying of the soil.
How do freezing thawing and drying contribute to soil creep quizlet?
How do freezing, thawing, wetting, and drying contribute to soil creep? ANSWER: –The soil expands and contracts, lifting particles and dropping them a slight distance downslope. -Gravity exerts a much stronger force when the soil is wet and thawed.
Do freeze/thaw cycles contribute to soil creep?
The creep of soil and other unconsolidated material can be a "grain by grain" process facilitated by freeze-thaw cycles. As water between grains crystallizes to ice and expands, a grain is pushed away from the surface of the ground.
How do freezing thawing wedding and drying contribute to soil creep?
How do freezing, thawing, wetting, and drying contribute to soil creep? The soil expands and contracts, lifting particles and dropping them a slight distance downslope.
What is the main cause of creep?
In materials science, creep (sometimes called cold flow) is the tendency of a solid material to move slowly or deform permanently under the influence of persistent mechanical stresses. It can occur as a result of long-term exposure to high levels of stress that are still below the yield strength of the material.
How does a creep occur?
creep, in geology, slow downslope movement of particles that occurs on every slope covered with loose, weathered material. Even soil covered with close-knit sod creeps downslope, as indicated by slow but persistent tilting of trees, poles, gravestones, and other objects set into the ground on hillsides.
What is important in soil creep?
They defined soil creep caused by burrowing agents (e.g., worms, ants, and moles) and tree throw as the main factor for creeping soil. With the help of OSL, they determined when soil grains had last visited the soil surface and measured vertical soil mixing rates of 0.1–0.4 mm yr−1.
How do freezing thawing wetting and drying?
How do freezing thawing wetting and drying contribute to soil creep? ANSWER: –The soil expands and contracts lifting particles and dropping them a slight distance downslope. -Gravity exerts a much stronger force when the soil is wet and thawed.
What causes creep and how can it be recognized?
creep is caused by the repeated expansion and contraction of the regolith which may be caused by repeated freezing and thawing or wetting and drying. creep can be recognized by tilted trees tilted fences and displaced retaining walls.
What are the conditions necessary for soil creep to occurs?
Soil creep occurs in moist soils where the water acts as a lubricant. It is more likely to occur on steeper slopes and in areas where the soil is thick. It may also be caused by the alternate wetting and drying or alternate freezing and thawing of the soil.
How does a soil creep occur?
Soil creep is a process operating at the granular scale. It happens on gentle slopes and is noticeable from the wavy surface it produces. Damp soil moves very slowly down the slope as the weight of water pushes it forwards. Rain splash may release soil grains that fall further downslope.
Why does temperature affect creep?
As the temperature increases, the stress-strain curve continually shifts upward. As the temperature increases and the creep time increases, the average creep modulus of similar materials in soft rock decreases.
What is creep movement?
creep, in geology, slow downslope movement of particles that occurs on every slope covered with loose, weathered material. Even soil covered with close-knit sod creeps downslope, as indicated by slow but persistent tilting of trees, poles, gravestones, and other objects set into the ground on hillsides.
What causes creep mass movement?
Gravity always causes the rocks and soil to settle just a little farther downslope than where they started from. This is the slow movement that defines creep. Creep can also be seen in areas that experience a constant alternation of wetting and drying periods which work in the same way as the freeze/thaw.
Why does water frozen in the cracks of a rock help to break down the rock?
Why does water frozen in the cracks of a rock help to break down the rock? Water expands when frozen & physically forces the rock apart.
Which of the following are factors that affect rates of weathering?
Rainfall and temperature can affect the rate in which rocks weather. High temperatures and greater rainfall increase the rate of chemical weathering. 2. Rocks in tropical regions exposed to abundant rainfall and hot temperatures weather much faster than similar rocks residing in cold, dry regions.
Which process contributes to the development of soil creep?
Colder climates- repeated thawing and freezing of water within the soil contributes to creep. Landslides- more rapid mass wasting of rock, soil, or both,.
How does time and temperature affect creep?
At higher temperatures the creep rate falls off less rapidly with time, and the creep strain is proportional to a fractional power of the time, with the exponent increasing as the temperature increases and reaching a value of -+ at temperatures of about 0.5 T,.
Is creep temperature dependent?
Creep, as a time-temperature dependent phenomenon, affects long-term reliability of thermoplastic polymers. Creep strain generally increases with temperature due to low creep resistance (1).
What factors contribute to soil creep?
creep is mainly controlled by slope angle and curvature, along with soil depth, texture, density and moisture.
How do freezing and thawing actions of water affect rocks?
Over time, this freeze-thaw process pushes pieces of rocks apart, eventually causing pieces of the rock to break off into smaller fragments. The freeze-thaw cycle is what gives water the ability to break rocks apart, but the process is also sometimes called frost wedging. Either term is acceptable.
How is the freezing and thawing of water a part of the weathering process?
Water seeps into cracks in the rocks, and, as the temperature drops below freezing, the water expands as ice in the cracks. The expansion exerts tremendous pressure on the surrounding rock and acts like a wedge, making cracks wider. After repeated freezing and thawing of water, the rock breaks apart.
Which of the following weathering process involves the constant freezing and thawing of water?
This specific process (the freeze-thaw cycle) is called frost weathering or cryofracturing. Temperature changes can also contribute to mechanical weathering in a process called thermal stress.
How does freezing water cause the weathering of rocks?
Freeze-thaw Weathering When water seeps into rocks and freezes, it expands and causes the rock to crack. When water transforms from a liquid state to a frozen state, it expands. Liquid water seeps into existing cracks in the rock, freezes and then expands those cracks.
Why is temperature an important factor in creep failure?
These elevated temperatures result in increased creep deformation rates, more rapid oxidation and corrosion (thinner walls and higher stress) and hasten the onset of creep failures. An increase of 60oF (from 1040oF to 1100oF for example) will decrease creep life by 90%.
Why is creep affected by temperature?
As the temperature increases, the stress-strain curve continually shifts upward. As the temperature increases and the creep time increases, the average creep modulus of similar materials in soft rock decreases.
What does creep depend on?
Creep may be defined as a time-dependent deformation at elevated temperature and constant stress. It follows, then, that a failure from such a condition is referred to as a creep failure or, occasionally, a stress rupture. The temperature at which creep begins depends on the alloy composition.
How is creep affected by temperature?
As the temperature increases and the creep time increases, the average creep modulus of similar materials in soft rock decreases. As the axial pressure increases, the creep strain deformation increases continuously, and the larger the axial pressure, the more significant the creep strain changes.
What type of weathering is freezing and thawing?
There are two main types of physical weathering: Freeze-thaw occurs when water continually seeps into cracks, freezes and expands, eventually breaking the rock apart. Exfoliation occurs as cracks develop parallel to the land surface a consequence of the reduction in pressure during uplift and erosion.
What is freeze and thaw cycle?
A freeze-thaw cycle is the freezing and thawing of water inside pipes associated with the winter months. The temperature even in winter is never uniform, and fluctuates frequently. This causes the water inside pipes to freeze in very frigid temperatures and thaw when temperatures rise a little.