Avalanches is a process of mass movement of land and / or mass destruction of rocks of slope constituents moving down the slope due to disturbance of soil stability or rock composing slope.
The problem of avalanches often occurs due to geographical conditions in some places have high rainfall and earthquake potential areas. High rainfall is considered a major factor of sliding because water can erode a layer of sand, lubricate rocks or increase the moisture content of a clay so as to reduce shear strength. The likelihood of avalanche due to rain still has to be attributed to several factors such as local topography, geological structure, soil seepage properties and development morphology.
The hilly topographic conditions with an almost perpendicular slope lead to many unstable slopes. The phenomenon of instability of a slope can be classified into slope failure and landslide. Slope and landslide collapse can occur on a dug or on a heap.
The causes of the slope collapse on a quarry will be very different from a heap. An excavation is a case without loading where the soil is removed, therefore causing a voltage support in the soil. In contrast, soil elevations and exhaust deposits are the case of loading and the period of execution is the most critical period due to the occurrence of pore pressures during execution with the consequence of effective tension reduction.
The problems that are generally behind the landslide disaster are:
- Almost perpendicular slope will affect slope stability. The existence of infrastructure that stands on the slopes cannot be moved so that the land to make the slope of the slope is very limited.
- Geographical conditions that have high enough rainfall that increases pore water content thus reducing shear strength.
- Increased pore water content in case of heavy rain due to malfunctioning drainage channels in the construction which resulted in inhibition of the flow of water that will come out so that the pore water pressure increases and potentially lead to sliding.
- Over the landslide location has changed the function of the green area into a settlement that causes the reduction of the water catchment area so that changes in groundwater content in the cavity and will decrease the stability of the soil.
The types of slopes, in the field of civil engineering there are two types of slopes, namely:
Natural Slope (Natural Slopes)
Natural slopes are formed due to natural processes. Disturbance to stability occurs when soil shear resistance cannot compensate for forces that cause a slip in a landslide field. Natural slopes that have been stable for years may experience a landslide caused by several things.
On the natural slopes, the critical aspects that need to be studied are the geological and topographic conditions, the slope of the slope, the type of soil layer, the shear strength, the underground water flow and the speed of weathering.
Artificial Slope (Man Made Slopes)
Artificial slopes can be divided into two kinds:
– Original artificial slope / excavation slope (Cut Slope)
This slope is made from the original soil by cutting with a certain slope. For the construction of roads or water lines for irrigation. The stability of the cut is determined by the geological conditions, the technical nature of the soil, the water pressure from seepage, and the way of cutting.
– Compacted Artificial Soil Slope / Embankment Slope (Embankment)
Soil compacted for highway embankments, dams, railroad bodies. The technical nature of the embankment is influenced by the hoarding and degree of soil density. To find out more about the artificial slope, you can see it in http://www.maccaferri.com/my/solutions/soil-nailing/.
A most common technical collapse is the landslide of an excavation or heap. In the event of an avalanche in the clay soil, it is often obtained as long as a circular arc. This circular arc can cut the surface of the slope, through toe slopes or cut deep seated and cause an increase in the base.