How to Improve Stability of Slope of Soil Mass?
Man-made and natural slopes that are suspected to be unsafe against sliding can be made usable and improved for safe operation. Though various techniques are developed to make slope stable but all method are serving to either weight reduction or improve shear strength of soil mass in suspected failure zone across the cross-section of slope. Mass reduction process reduces the sliding susceptibility of a slope.
The following measures are suggested to improve stability:
a. Providing a flat slope-trimming steeper one reduces weight of soil mass that tend to slide leading slope failure. This measure can be adopted anywhere across the slope.
b. A berm can be constructed to improve resistance against movement. The berm is located below toe of slope and frequently used where failure of base is suspected to be occurred. Dear reader in our upcoming posts we will learn about loading berm to stabilize slope of dam and its foundation.
c. Preventing infiltration of water from surface runoff or ponding.
d. Lowering of subsurface water level by providing efficient drainage which also reduce seepage force and thus helps us to increase stability of slope.
e. Any stabilization technique of soil also helps to increase stability of slope. The stabilization may be mechanical stabilization or chemical stabilization. We have discussed some techniques and some will be published soon.
f. Retaining walls and sheet piles can be constructed to increase stability of slope by providing lateral support. But when economy is concerned these are very expansive measure. In construction of these structures care should be taken to provide adequate drainage, otherwise such massive structure may collapse.
g. In specific zone of earth slope application of grouting and injecting cement or similar compounds also help to increase stability of slope.
h. For cohesive soil expelling out of water by consolidation is also a measure to increase stability of soil mass at slope. In this purpose we can use surcharge, electro-osmosis and any other method that consolidate soil.
i. In case of cohesionless soil we can increase shear strength of soil by densification of soil mass. We can use here
-Explosive
– Vibroflotation
– Terra probe
The increase is shear strength obviously increase stability of soil slope.
Application of explosive was discussed in this blog. Vibroflotation is a method to compact soil up to 30 m depth. The vibrofloat have a rotating mass placed eccentrically which results horizontal vibration when sunk is desired depth. It is generally applicable to sandy soil. Terra probe is a similar method of vibroflotation techniques but less effective than vibroflotation method.
Of these measures, considering economy, if possible, relatively less expansive methods like drainage control and flattening of slope control are usually preferred.