TYPES OF RETAINING STRUCTURES [GRAVITY AND NON-GRAVITY]

From the point of view of the source from where the retaining structure derives its stability, we basically have two types of retaining structures, viz., gravity And this non gravity Type.

gravity Type structures are normally ‘rigid’ and non gravity Type, ‘flexible’.


gravity The type of retaining structure derives its stability primarily from the own weight of its components, whereas in the case of non gravity Thus, the factors contributing to stability are other than gravity or self-weight forces.

Figure 1
Figure 1
line drawing number 2
line drawing number 2
Fig-3
Fig-3

Older masonry type retaining walls (Figure-1) and comparatively newer reinforced concrete retaining walls—both cantilever (Figure-2) and counterfort (Figure-3) types—are examples of gravity type of retaining structures, but with the difference that, while in the case of a strong masonry wall, the wall’s own weight alone is the main source of stability, what contributes to stability is not only the weight of thinner RC structural elements , but in the latter case also of soil on the base slab.

Image-4
Image-4
Fig-5
Fig-5

There are several types of retaining structures that derive their stability from sources other than gravity. The most prominent example of this category is sheet pile wall which is too thin, whether in steel, reinforced concrete or wood, to achieve any stability by its own weight. Whereas in the case of this type of cantilever wall (Figure-4), the only source of stability is enter in the soil below, enter And anchor ground Contribute to the stability of the bulkheads anchored together (Fig. 5).

fig-6
fig-6
Fig-7
Fig-7

walls of the diaphragm (Figure-6) and bored pile walls (‘Contiguous’ and ‘Secent’ types – Figure -7) are thin structures that are always anchored to the side soil using ‘Prestressed Ground Anchors’ when called upon to act as retaining structures Is. Hence their stability in this state mainly comes from anchor ground,

Fig-8
Fig-8

The most modern type of flexible retaining structure is reinforced earth, where a thin ‘facing skin’ is held in position by a large number of thin ‘reinforcing strips’ and run through the backfill (Fig. This type of wall causes its retention action mechanical friction Between reinforcing strips and backfill soil. It can in a sense refer to it as the facing skin in the backfill, even though the facing skin has a very minor role in this system. However, a major difference between the anchoring action in the case of bulkhead and diaphragm walls on the one hand and reinforced earth on the other is that while the former two can be described as examples of ‘terminal anchorage’, the latter represents Is the case of ‘constant friction anchor’.

Among the non-traditional types of retaining structures should be mentioned crib wall And gabion Both of which are primarily gravitational structures, but are somewhat flexible in nature. Even ‘tetrapods’ placed along coastlines as a protective measure against ocean erosion can be considered as falling under the broader category of retaining structures.

Author

Dr. Nain P. Kurien



PSG College of Technology

Er. Mukesh Kumar

Photo of author
Er. Mukesh Kumar is Editor in Chief and Co-Funder at ProCivilEngineer.com Civil Engineering Website. Mukesh Kumar is a Bachelor in Civil Engineering From MIT. He has work experience in Highway Construction, Bridge Construction, Railway Steel Girder work, Under box culvert construction, Retaining wall construction. He was a lecturer in a Engineering college for more than 6 years.