DISASTER MANAGEMENT

1. CONSTRUCTIONTECHNIQUES
AND MEASURES:
LANDSLIDE
DEVESH TRIPATHI
B ARCH 3 RDYEAR

2. Landslide control measures
Landslide control measures are implemented after adequate study and
understanding of the causes of the landslide occurrences, the landslide inducing
processes and their mechanism.The foremost requirements for slide control are
reliable information on the geologic structure of the ground adjoining the land
under considerations, hydro-geological study as well as geomorphological
attribute which may directly lead to a failure of the slope. Landslide control
measures include two types of works,
(i) prevention works and (ii) detention works.
The former intends to stop or mitigate a landslide motion by changing the
natural
conditions, such as, topographical, geotechnical and water conditions at a
landslide site, while the latter aims at detaining a part of the landslide motion or
the entire landslide motion using structural control works.

3. Surface Drainage:
• The first preventive remedial measure is to control the surface drainage of
the landslide area.
• All perennial or temporary jhoras (small streams) or water
courses should be prevented from entering the slide area.
For the immediate provisional diversion of water,
any pipes available may be used.
• For discharging rain water from the slide, open
ditches of adequate dimensions, and modifying gradient are done.
• At the sometime, the ground surface should be leveled and depressions and all cracks
• need to be so filled as to ensure a continuous runoff of surface.
• They are paved either by natural stone of suitable properties, or by concrete tiles set into
a sand
• bed and the joints are seated by cement mixture. In case of sandy soils, ditch
• bottom and walls are consolidated by asphalt, bitumen or oil sprinkle.

4. Deep trench drains:
Filter fabric is an effective means of drainage for landslide control. Clogproof
filter fabric covered drains consist of a permeable gravel core, surrounded
by a filter fabric to prevent clogging.The gravel size is either 16-32 mm or 35-70
mm to ensure a sufficiently high void ratio.The average amount of material
needed per metre of drain length is about one cubic metre of gravel and five
square metres of filter fabric.

5. Retaining wails and similar structures:
i. The foundation of the retaining walls should lie on the
ii. hard strata or rock and should be free from scour, frost, and surface water.
iii. The base of the foundation must be wide enough to distribute the
pressure over the foundation.
iv. The stone to be need should be more than 0.14 cubic metres in size,
v. and the width of each stone should be more than 1.5 time its height.

6. Masonry walls:
• Retaining walls above four metres in height are built either in lime or cement mortar
masonry or in dry stone masonry with 0.6 m wide mortar masonry bands three to
found metres apart, laid both in horizontal and vertical directions.
• The top thickness is usually 0.6 m, the front batter one to four, and the back face
vertical.
• Masonry courses are made
• normal to face batter and the back of the wall can be finished rough.

7. Concrete retaining walls:
• The stability of the whole body of the walls and the stem is considered in
the design.The body of the walls is taken to include the mass of soil directly
above the heel of the wail and earth pressure.
• Weep holes are generally kept in the wall. Several landslides have been
protected by Concrete retaining walls inside and outside the town.

8. Anchored walls:
• A deep pre-stressed anchor is also applied for stabilizing soil slopes.
• Walls with pre-stressed anchors have a major advantage because they actively oppose
the movement of the soil mass, rather than behaving passively as in thecase of
unstressed anchors and gravity structures.
• Pre-stressed anchors are employed either in combination with retaining structures, or
alone, to reduce the driving forces of a landslide and to increase the normal effective
stresses on its slip surface.

9. THANKS…