What makes a slope stable?

Slope stability is ultimately determined by two factors: the angle of the slope and the strength of the materials on it.

How do you know if a slope is stable?

If the forces that resist the movement are greater than those driving the movement, the slope is considered stable. A factor of safety (FS) is calculated by dividing the resistance by the driving forces. A factor of safety greater than 1.00 suggests that the slope is stable.

What causes instability in slopes?

1. Erosion: The wind and flowing water causes erosion of top surface of slope and makes the slope steep and thereby increase the tangential component of driving force. 2. Steady Seepage: Seepage forces in the sloping direction add to gravity forces and make the slope susceptible to instability.

What is a stable slope angle?

The angle of repose is the steepest angle at which a pile of unconsolidated grains remains stable, and is controlled by the frictional contact between the grains. In general, for dry materials the angle of repose increases with increasing grain size, but usually lies between about 30 and 45 ^o.

What would make a slope less stable?

The results show that the rock fragments obstruct water flow on the slope and increase the pore water pressure. However, higher pore water pressure can cause the slope to become less stable. These indicate that the safety factor for the slope with rock fragment is lower than slope without the rock fragment.

How do you know if a slope is unstable?

Five common symptoms of slope instability are:

1. Visible cracks;
2. Leaning or curved trees, guardrails and other structures;
3. Toe erosion;
4. Hummocky slope surface; and.
5. Moisture changes.

How do you stabilize slopes?

Slopes can be stabilized by adding a surface cover to the slope, excavating and changing (or regrading) the slope geometry, adding support structures to reinforce the slope or using drainage to control the groundwater in slope material.

What are slope protection methods?

Slope protection approaches discussed below include erosion control blankets and turf reinforcement mats, which can also be used for ditch protection, surface roughening, slope drains, gabion structures, and cellular mats.

What is slope protection works?

The restraint work consists mainly retaining structures, anchoring, piling and other slope protection works. • Control Measures The control measure is mainly composed of the earthwork, water management and bio-engineering work. Earthworks and Drainages are essential factors in improvement of slope stability.

How do you stabilize a cliff?

Cliff stabilisation

1. Littoral strip reloading: compensate littoral imbalance caused by marine erosion by placing sand or pebbles at the foot of the cliff. …
2. Re-vegetation: managing existing vegetation to regain damaged areas or establishing a vegetation cover on the slope to limit the risk of instabilities.

Is slope Stabilisation hard or soft engineering?

Soft engineering techniques involve working with nature to manage the coastline. Techniques include cliff stabilisation, dune regeneration and managed retreat.

Is Cliff Stabilisation hard or soft engineering?

soft engineering

Cliff stabilisation is a form of soft engineering – these methods are usually a more sustainable and sometimes cheaper approach to coastal defences, using natural processes to protect the shoreline against flooding and erosion.

Why are some cliffs more stable than others?

Cliff morphology also is influenced by the permeability of a rock. For example: cliffs which have impermeable rock overlying permeable rocks limit percolation and therefore are more stable, preventing mass movement.

What makes a cliff a cliff?

Cliffs are usually formed because of processes called erosion and weathering. Weathering happens when natural events, like wind or rain, break up pieces of rock. In coastal areas, strong winds and powerful waves break off soft or grainy rocks from hardier rocks. The harder rocks are left as cliffs.

Is cliff drainage a soft engineer?

What are the strengths of cliff regrading? Draw a labelled diagram to show how cliff regrading works. This is a method of soft engineering because it involves working with the natural environment, is low cost and is sustainable.

What factors affect cliff profiles?

Cliff profiles are influenced by geology, especially the resistance (to erosion) of the rock, and the dip of rock strata in relation to the coastline. Joints are fractures in rocks created without displacement.

What factors determine how resistant to erosion cliffs are?

The ability of waves to cause erosion of the cliff face depends on many factors. The hardness (or inversely, the erodibility) of sea-facing rocks is controlled by the rock strength and the presence of fissures, fractures, and beds of non-cohesive materials such as silt and fine sand.

What factors will determine how resistant to erosion these cliffs are?

The resistance of cliffs to erosion comes from geological conditions as well as native plants that hold the cliff more firmly in place. As these factors change, cliffs will become more unstable. High erosion rates are also seen at the mouths of rivers with dams.

What is main factor controlling cliff erosion?

The wave assailing force is greatly controlled by water level, nearshore topography, and talus or ice cover at the cliff base. Fluctuations of these controlling factors produce temporal variations in erosion rates. The most important factor in dramatic erosion is an abnormal rise in water level, known as storm surges.

Which 3 factors influence the rate of erosion at the coast?

The key factors which affect coastlines are:

• The rock type/geology (see map below). …
• The fetch of the wave and the strength of the wind. …
• The angle of the slope – steep slopes erode more violently and frequently.
• Weather conditions – freezing temperatures and heavy rain increase weathering and the rate of erosion.

What factors affect erosion?

The erosion potential of any area is determined by four principal factors: the characteristics of its soil, its vegetative cover, its topography and its climate.

What are the factors affecting the rate of erosion?

The more erodible the soil, the greater the rate of erosion and the shorter the distance to maximum soil movement. Major factors that affect the amount of erosion are soil cloddiness, surface roughness, wind speed, soil moisture, field size, and vegetative cover.

What factors impact erosion on a sloped surface?

The main factors influencing soil erosion include the net rain excess, the water depth, the velocity, the shear stress of overland flows, and the erosion-resisting capacity of soil. The laws of these factors varying with the slope gradient were investigated by using the kinematic wave theory.

Is the laying down of sediment carried by wind water or ice?

Deposition

Deposition is the laying down of sediment carried by wind, flowing water, the sea or ice. Sediment can be transported as pebbles, sand and mud, or as salts dissolved in water.

What are 4 factors that affect erosion?

The erosion potential of any area is determined by four principal factors: the characteristics of its soil, its vegetative cover, its topography and its climate.

What is it called when water freezes in a crack and a piece of the rock breaks off?

When water freezes, it expands. The ice then works as a wedge. It slowly widens the cracks and splits the rock. When ice melts, liquid water performs the act of erosion by carrying away the tiny rock fragments lost in the split. This specific process (the freeze-thaw cycle) is called frost weathering or cryofracturing.

What causes deposition?

Deposition happens when rocks, pebbles, or particles, composed of soil, clay, or silt, are carried from one location and left at another. These particles, called sediments, are carried by wind and water action, where blowing wind or flowing water will pick up and carry the materials until they fall out of the solution.