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Gabion structure

Gabion structure Submitted by-sweta M. TECH

OUT LINE 1. General Information About Gabion 2. Introduction 3. Characteristics 4. Uses Of Gabion 5. Gabion Structures Employment 6. Advantages Of Gabions 7. Construction Of Gabion Structure 8. Construction Steps 9. Computation Of Construction Cost Of Gabion. 10. Computation Procedure. 11. case study 12. reference

general information about gabion v. Originated IN ITALY. v. Basically rectangular wire mesh. v. Filled with stones. v. Size of the stones filled is always greater than the mesh opening.

INTRODUCTION ØAccording to oxford dictionary : : A cylindrical basket or container filled with earth , stones, or other material and in civil engineering works. Ø Is a wire mesh cage or basket filled with stones. ØA gabion is a big wire box full of small stone. .

CHARACTERSTICS: üFLEXIBLE üPERMIABLE üECONOMIC $ üBOXES ARE MADE OF GALVENISED WIRE.

USES OF GABION ØGully Control. ØTorrent Control ØLandslip Control , land Slide Control ØRiver Bank Protection Works

GABION STRUCTURES ARE EMPLOYED(Gupta&dalre 1967 ØAs a retaining wall Gabion structure used as retaining wall is called as gabion retaining wall. USES - §Unstable condition §Constructed to any height and shape.

Ø As a spur: §For controlling stream bank erosion. §Depth of spur’s foundation should be kept deeper towards upstream side. ØAs a drop structure: §Gabion structure used as a drop structure are called as gabion drop structure. §Reduces gully gradient. to serve as silt trip. §It is used where the drop height is more than 1 m. § 5 cm thick concrete should be furnished after settlement

Ø As a flexible apron: §Gabion aprons are extensively used as flexible apron to act as a revetment , retaining wall to protect the existing structure.

§Gabion structure as revetment Its main function is to provide the blanket type protection to the affected surface. §Gabion structure for lining The gabion also employed for lining the beds and banks of the water cores Maximum slope for the channel lining is 1: 1 or 1. 5: 1.

Advantages of gabions 1)Efficient 2)Permanent 3)Easy to construct 4)Economical Special features which proves as advantages 1)It is flexible structure 2 It is a permanent structure 3)It is a stable structure 4)It is a economical structure

Construction of gabion structure Material required – 1. Galvanised wire 2. Hexagonal triple twisted mesh in the size ranging from 7. 5 to 15 cm 3. Wire no-8 gauge, less than 10 gauge is not used

Construction steps 1)Assembled each gabion unit by binding there vertical edges with the help of about 12 -15 cm long wire ties. it is good to make 5 ties per metre height. 2) As per plane place, few empty unit on position and tie them with the adjacent boxes, using at lest 5 wire per metre.

3) With the help of standard fence stretcher, stretch the box before filling the stones, to provide effective alignment after they are tied together. 4)Filled the rocks into stretched boxes and also insert connecting in each cell. When the box is filled by its 1/3 portion, the first four wires, two in each direction in each cell are placed. repeat the procedure until the box is filled by its 2/3 rd portion

Contd. . 5. when filling operation of stones to construct the gabion boxes has been completed , then tie the lid from sides and the end portions. A half meter long ‘pinch bar ’ can be used.

Computation of construction cost of gabion parameter considered: 1. size of gabion box(length, width and depth) 2. capacity of box (m³) 3. area of wire mesh in each gabion (m²) 4. density of wire used (kg/m³) 5. cost of mesh construction (Rs/kg) 6. labour charge per box including construction cost of wire mesh. 7. cost of rock filling (Rs/m³)

computation procedure : step(1): find out the area of mesh involved in each gabion box. Step(2) : calculate the weight of wire needed per box. it is given as weight= density of wire x area of mesh in each box. Step(3) : calculate cost per box. it is obtained as: weigh of box x cost. step(4) : estimate labour charge per box including construction cost of wire mesh, which is computed as: labour charge x area of wire mesh of one gabion box. step(5) : compute the cost of rock filling per 100 m³. It is given as cost of rock filing x capacity of gabion. Step(6) : find the total cost of construction which is the sum of Step(3), Step(4) , Step(5).

CASE STUDY : PERFORMANCE OF GULLY PLUG STRUCTURE(GABION) IN BLACK CLAY SOIL. D. H. RANADE, L. K. JAIN, S. K. VISHWAKARMA S. M NARULKAR and A. S. TOMAR AICRP On Dry land Agriculture, College of Agriculture , J. N. K. V. V campus, Indore INDIA Published in INDIAN JOURNAL OF SOIL CONSERVATION Volume 29 -2001

ØINTRODUCTION The study was carried out in the year 2000 to assess the cause of failure in gully reclamation in the black soils of malwa region of village pipliyatapha. Gabions had been constructed in the lower reaches of river gambhir under hingoia pipliyatapha watershed area during the year 1991 -92 The soils of experimental area are highly erodible(clay 55 percent). The average annual rainfall of area is 958 mm. The total length of gully is found to be 216 m in the year 2000(which was only 195 m in the year 1992).

MATERIALS AND METHODS ØTwo structures were constructed at vertical interval of 2 m i. e. at distance of 44 m and 140 m from gully head. ØIt was observed that the gabion were constructed in narrow sections of the gully in order to reduce cost of construction. ØIt was also noticed that the height of the first gabion was 1 m but is increased to 2 m in case of second gabion.

SI No. Design of the existing structure Dimensions(m) Structure -1 Structure-2 A Hydrological design details i) • ii) Length of crest 3. 00 2. 65 Head over the crest 0. 50 1. 00 B) Hydraulic design details i) Depth of cut-off wall 0. 00 ii) Depth of head wall 1. 00 2. 00 iii) Length of head wall extension(on one side) 1. 00 Iv Depth of toe wall 0. 00 V Length of apron 0. 00 Vi Length of side wall 0. 00 vii Length of wing wall 0. 00 Solar Wonders, © 2007 Florida Solar Energy

DETAILS OF EXISTING GULLY PLUG STRUCTURES

ØIt was observed that when runoff water entered from the wider section to narrow section(3. 00 to 2. 65 m width) ØIts velocity increased tremendously an and crossed the erosive velocity limit. ØInstead of reclaiming the gully, it increased in gully width and depth. ØIn this case the gully bed deepening up to 16 m (0. 4 m) from second structure while it was limited to 9. 50 m(. 73 m)in the first structure.

Results and discussion Øeven after structural failure, The head wall of gabion remained at its location this indicates that the gabion is very stable structure. ØFrom the above study, it is observed that the gabion structure should be constructed in a fairly reasonable uniform section of gully instead of narrow section.

SEDIMENT RETENTION BY GABION STRUCTURE IN BUNGA WATERSHED P. K. GOEL, J. S. SAMRA AND R. C. BANSAL Central soil and water conservation research and training institute, research centre, chandigarh. Published in INDIAN JOURNAL OF SOIL CONSERVATION Volume 24 -1996

INTRODUCTION ØThe cost of gabion construction is almost ½ to 2/3 rd of the cement masonry( juyal et al. , 1992). Ø gabion structures have relatively long life (20 -25 years) in comparison to cement masonry permanent structure

STUDY AREA Ø bunga-II watershed project area is located in bunga, Ambala (Haryana) and situated at 30ᵒ 42’N latitude and 77ᵒ 10’ E longitude. ØAverage rainfall o area is 1100 mm. ØEight crate wire stone check dams constructed in the catchment of water harvesting dam of bunga-II watershed project in ambala district of haryana were selected for the assessment of their effectiveness in retaining sediment.

DESIGN DETAILS OF CRATE WIRE STONE CHECK DAM IN THE CATCHMENT OF BUNG-II dam Structure Number Capacity of the structure up To crest level(cum) Capacity lost in (cum) At the time After one Of(june 199 year(1991) 1) constructio n One year After two year(1992) Percentag e of capacity Two year lost in two years 1 642. 2 537. 2 290. 0 105. 0 352. 2 54. 84 2 550. 9 464. 5 65. 2 86. 4 485. 7 88. 15 3 380. 4 298. 5 32. 6 81. 9 347. 8 91. 43 4 295. 9 198. 2 * 97. 7 * * 5 207. 5 200. 3 164. 3 7. 2 43. 2 20. 81 6 1603. 9 1132. 2 837. 0 471. 7 766. 9 47. 81 7 543. 3 425. 3 315. 2 118. 0 228. 1 41. 98 8 134. 6 112. 2 43. 7 22. 4 85. 9 63. 81

ØWithin a short span of two years, loss in retention capacity of structures ranged from minimum 20. 18 percent to maximum 91. 43 pecent with average loss of 58. 40 percent. ØOut of eight structures under study, two(structure number 2&3)lost almost 90% of their capacity due to sediment deposition ØThe detained sediment was found conducive supporting the growth of vegetation which in tern further improved control of erosion. ØThis indicate that the crate wire stone check dams are very much effective in retaining the sediment which would have found its way to reservoir resulting in loss of valuable storage capacity.

REFERENCES Text book of SOIL AND WATER CONSERVATION ENGINEERING by : R. Suresh Google images. Ranade, D. H. , Jain, L. K. , Vishwakarma, S. K. , Narulkar, S. M. , Tomar, S. M. , 2001, performance of gully plug structure(gabion) in black clay soil region-A case study. indian journal of soil conservation 29 (1): 88 -90 Goel, P. K. , Samra, J. S. , Bansal, R. C. , 1996, sediment retention by gabion structure in bunga watershed. indian journal of soil conservation 27 (2): 107 -110

Gabion s are used as : Gully control structure As wellas decoration purposes.

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