1. 4.5 REINFORCED EARTH (terre armee) FILLS CAN BE FORMED PLACING "REINFORCEMENTS" IN THEM AND COMPACTING (GLASS FIBRE REINFORCED, PLASTIC FIBRE, TRYLENE FIBRE, FLEXIBLE GALVANISED STEEL STRIPS ETC.) ( 5 MM THICK & FLEXIBLE). THE STRIPS ARE LAID IN THE LAYERS OF THE FILL AND BOLTED TO THE RETAINING WALL AT THE FACING OF THE FILL. THESE STRIPS EXTEND SUFFICIENTLY FAR INTO THE SOIL BEHIND THE WALL. THE MAIN IDEA IS THAT WHEN SLIDING STARTS TO OCCUR IN THE SOIL (ZONE 1) THE ANCHORED STRIPS WILL PROVIDE A COMPLEMENTARY SHEAR STRENGTH (ZONE 2) AND THERE WILL STOP FURTHER DEFORMATION.

4. FILL MATERIAL - SEVERAL SPEC'S GENERALLY SHOULD BE GRANULAR IN NATURE PARTICLES D < 80 mM SHOULD BE < 15% MAX. PARTICLE SIZE: 350 MM MAX. 25 % OF THE FILL > 150 MM ANOTHER SPEC : MAX. PARTICLE SIZE 125 MM 63 mM PASSING < 10% OR IF 63 mM PASSING >10 % LL <45% PI<20% (WL ) (IP ) HOWEVER MAX. AMOUNT OF CLAY SIZE (2mm):10 % DESIGN

5. HORIZONTAL AND VERTICAL STRIP SPACINGS : Sh & Sv Schlosser Mc Kittr. AT DEPTH Z, STRIP TENSION : Ts = K.  v. Sh. Sv Ministere de Trans. K for z < 6 m K for z > 6 m K=KA Earth pressure coefficient Calculated vertical stress e.g. using Meyerhofs coeff. distribution)

6. THIS IS BASED ON THE OBSERVATIONS OF FULL SCALE WALLS SF = 3 IS USED TO ULTIMATE TENSILE STRENGTH OF GALVANISED STEEL. BOND FAILURE Effective bond length is that projecting beyond the "failure surface" If not measured in a shear box coefficient of friction is taken to be 0.40 for plain strips and tan  ' for ribbed strips or 0.90 (arc tan 42) (m =  tan  ',  = 0.46-0.50, plain strips 0.48 tan 40 = 0.40)

7. FOR H < 6 M F IS ASSUMED TO REDUCE LINEARLY FROM UNITY AT THE FREE SURFACE TO TAN  ' AT A DEPTH OF 6 M. TAKING A FACTOR OF SAFETY OF 1.5 AGAINST BOND FAILURE THE REQUIRED BOND LENGTH L A AT DEPTH Z IS Ministere desTransports 1979

8. L A IS ≥ 0.8H OR ≥5 M WHICH EVER IS GREATER. THIS IS INTERNAL STABILITY. THE STRUCTURE MUST BE CHECKED FOR EXTERNAL STABILITY. LET US GO THROUGH THE STEPS. I. CHECK STABILITY OF EACH LAYER BY CALCULATING THE MAX. TENSILE FORCE T. PER METER RUN OF WALL TO BE RESISTED IN i th LAYER. THIS FORCE IS TAKEN TO BE THE SUM OF THE TENSIONS CREATED BY FIVE POSSIBLE LOADINGS.

9. Due to K A. .z i Due to surcha rge q Due to strip loading at top of wall Due to horizontal loading at top Due to bending moment cause by external loading on wall

10. II. HAVING EVALUATED Ti CHECK TENSILE FAILURE & PULL - OUT FAILURE Required reinforcement perimeter per meter run of wall total length of each reinforcement in the i th layer. F.S.

11. III. ONCE THE STABILITY OF EACH AND EVERY LAYER OF REINFORCEMENT HAS BEEN CHECKED THE OVERALL STABILITY OF SEVERAL TRIAL WEDGES IS CHECKED USING A GRAPHICAL METHOD. Effective bond length