Specified backfill material shall be placed and compacted to minimum Standard

Specified backfill material shall be placed and

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insufficient shear strength to perform as designed. Specified backfill material shall be placed and compacted to minimum Standard Proctor 95% in lifts not to exceed 9” vertical and shall comply with local standards.
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SOIL DATA Recommendatio n Of use for backfill Soil Description Soil Classification Angle of Internal Friction Unit weight of Soil Excellent Stone, Gravel, Sand 1 & 2 GP, GW, GM, GC, SW, SP 30-36 100-135 pcf Good Clayey Sands, Silty Sands 3 SM, SC 28-32 110-130 pcf Poor Soft Clay, Soft Silts 4 ML, CL, OL 25-30 110-125 pcf
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Bad Stiff Clay 5 CL, CH 25-30 50-110 pcf 1. Clean sand, stone and gravel GW, GP, SW, SP 2. Dirty sand and gravel of restricted permeability GM, GM-GP, SM, SM-SP 3. Stiff residual silt and clays, silty fine sands, clays, sands and gravels CL, ML, CH, MH,SM SC, GC. 4. Very soft to soft clay, silty clay, organic silt and clay: CL, ML, OL, CH, MH,OM. 5. Medium to stiff clay deposited in chunks and protected from infiltration: CL, CH For type 5 material H is reduced by 4 ft resultant Acts at a height of (H-4)/3 above base. Adapted from Terzaghi and Peck Filter Fabric Geotextile filter fabric is a vital component of any gabion gravity retaining wall. The void ratio of the stone fill confined within the gabion baskets allows for free drainage of the retained soils and requires a filter fabric be placed between the gabion wall and the specified backfill soil interface. The geotextile filter fabric will prevent loss of soil during drainage and drawdown. Gabion gravity retaining walls constructed without the placement of filter fabric will have a tendency to incur a loss of retained soils and grade elevation behind the gabion wall. The type of backfill soil specified will determine the type, and placement of the geotextile filter fabric. Call Terra Aqua for recommendations on filter fabric.
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Layout To provide the maximum resistance to soil forces the gabion baskets shall be placed with the length dimension of the gabion unit running from the back of the gabion wall to the front face of the gabion wall. This will result in the internal diaphragms being placed perpendicular to the wall face and parallel to soil thrust. When gabion units shall be placed with the length dimension of the gabion unit running parallel with the length dimension of the wall the vertical seams shall be offset. Compression Loads
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For gabion gravity retaining walls that are 15’ – 30’ in height the gabion basket foundation and bottom courses shall be placed in 1.5’ vertical lifts to better absorb the compression and shear stresses. Terra Aqua’s double twisted mesh gabions shall withstand compression loads of 60,000 – 80,000 pounds per square foot. The shear modulus of elasticity shall vary between 5,000 – 8,000 pounds per square foot and is relevant to deformation. Gabion Wall Face Configuration Terra Aqua gabion retaining walls can be designed and configured with a stepped front face or a smooth front face. When utilizing a gabion wall with a smooth front face, the gabion wall shall always be placed on a 6-10 degree batter and is not recommended for wall heights above 18’. Gabion walls with a stepped front face shall have a minimum 1’-1.5’ horizontal set back for each 3’ vertical lift.
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Gabion Wall Height
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