Grameen Sampark Final April 0... - pmgsy

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30 Apart from the above, both faces of Rat Trap Bonded Brick wall are checked with plumb bob, so both the faces are uniform. As a result there is no necessity to provide plastering. All that would be required is neat cement pointing and patching on one edge of the header course. Hence there will be additional savings in plastering. On completion of construction and curing the back filling was done with, in layers by local earth of Maximum Dry Density (MDD) 1.70 gms./cc. Then an earth compactor was employed to roll and compact the retained earth. The compactor was directed to start rolling from about 1 m away from the retaining wall and it came slowly towards the folded wall and went on rolling moving over the corbelled shelves with full capacity of vibration, which is equivalent to 36 M.T. Observations Through the wall was expected to fail severely, it did not. The stretches where the relieving shelves were not in existence, after repetition of about 3-4 cycles of full vibration rolling the vertical joint at the junction of fold on the pond side showed a line of crack which propagated along the line of weakness of brick masonry. The maximum width of crack was about 35 mm and it appeared at about 7250 mm from GL i.e. at about at ½ of height from GL. This clearly signifies that the failure was due to intensity of rolling load to this enormous extent. Not by virtue of back filling. The entire operation was Grameen Sampark video recorded. A selected portion of video recording is attached with a soft copy of this document. Progress of Field Tests A good number of folded plates were then applied to different locations of different projects as a cost effective tool for different height of retentions also. All are performing satisfactory till date. Some photographs are attached. In one instance folded plate has been applied to act as a guide bank beside a rivulet, which converges and passes through a narrow vented old culvert at the fag end of a PMGSY road – Rukunpur Khalshipara to Bangaljhi Ferry Ghat under Package No. WB/14/27. The stretch of road at this point would get inundated in every monsoon. Erosion was a predominant feature in this stretch. The folded plate brick masonry structure was used as a guide bank and it performed very well. It is observed that the fins of the folds acted like small spurs and the soil started depositing between the fins and chances of erosion has been reversed. Analysis of Economics A cost estimate has been done for three types of retaining wall 11.45 m. long to retain 1.5 m. high earth. The types of wall chosen are as under: - 1. Folded plate Rat-Trap Bonded wall. 2. Standard Trapezoidal Brick masonry wall. 3. Standard Trapezoidal Plain Cement Concrete (1:2:4) The following table shows the comparative analysis of the economics of the types of walls. Type of Wall Cost / running meter 1. Folded plate “Rat-Trap Rs. 1781.25 / m. bonded wall” 2. Brick masonry retaining Rs. 3498.54 / m. wall 3. Plain Concrete (1:2;4) Rs. 5104.60 / m. retaining wall
It shows that the cost of standard brick masonry retaining wall is almost double and concrete retaining wall costs 2.865 times more than the folded plate brick rat-trap bonded retaining wall. Hence, in other words the savings will be to the tune of 50% and 65 % respectively. Structural Analysis A preliminary analysis shows that the structure is marginally safe. But from experiment it reveals that the structure is highly safe. Therefore it can be concluded that certain parameters are yet to be considered. Further analysis in this light is being carried out. Conclusions Based on the limited experimental work and observation on some of the structures already constructed in the field, it can be concluded that: 1. The folded plate structure develops immense stiffness and sustainability against any and every kind of loads due to folded configuration. 2. There must be some structural uniqueness generated within the system, which contributes additional stiffness. 3. By virtue of this phenomenon the folded plate wall is found to be more efficient than the degree of efficiency found out by usual structural calculations. 4. The folded plate structure is very economical and can be used safely as retaining walls, cut off walls, and guide banks. Pradhan Mantri Gram Sadak Yojana Figure 1: Typical details for 1.500m. heigh (G.L. to Top Level) Retaining Wall SECTIONAL ELEVATION THROUGH XX PLAN OF RAT TRAP BRICK MASONRY RETAINING WALL All dimensions are in mm. Figure 2: Details of Rat Trap Brick Bonding ODD COURSES EVEN COURSES PLAN ODD COURSES EVEN COURSES L - JUNCTION ODD COURSES EVEN COURSES T - JUNCTION Grameen Sampark 31
Page 2 and 3: In this Issue Editorial 3 Potential
Page 4 and 5: 4 Potential Applications of Interlo
Page 6 and 7: 6 Interlocking Concrete Block Pavem
Page 8 and 9: 8 materials used for production of
Page 10 and 11: 10 Construction of Sub grade This i
Page 12 and 13: 12 Typical Pavement Compositions Ty
Page 14 and 15: 14 Guidelines for the use of In
Page 16 and 17: 16 layers due to repeated applicati
Page 18 and 19: 18 Subgrade Failure Criterion The b
Page 20 and 21: 20 A maximum of 50mm rut depth was
Page 22 and 23: 22 Stabilization of Soil Subgrade w
Page 24 and 25: 24 Changes in Cohesion and Direct
Page 26 and 27: 26 Increase in the C.B.R. value is
Page 28 and 29: 28 Laboratory Test (Under Vertical
Page 32: News in Brief General Body Meeting

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