[1] THE RUT DEPTH IS LIMITED BY A 41,000 LB (18636 KG) MAXIMUM TOW OUT FORCE ON THE MAIN LANDING GEAR STRUCTURE (SEE Figure 4-17)
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SOIL ANALYSIS
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757
AIRPLANE RECOVERY DOCUMENT
Figure 2-6 SOIL SURFACE CONDITIONS FOR SHORING (CRIBBING) REQUIREMENTS
APPROX CBR RANGE *[1] SURFACE MATERIAL SHORING (CRIBBING) REQUIRED FOR ROLLING LOAD SHORING (CRIBBING) REQUIRED FOR JACKING LOADS
MAXIMUM ALLOWABLE CONTACT PRESSURE MINIMUM CONTACT AREA REQUIRED MAXIMUM ALLOWABLE CONTACT PRESSURE MINIMUM CONTACT AREA REQUIRED
PER 20000 LB PER 10000 KG PER 150000 LB PER 70000 KG
PSI KG/CM2 (IN2) (CM2) PSI KG/CM2 (FT2) (M2)
2-6 SOFT WET CLAY OR WET ORGANIC SOIL 18 1.25 1,100 8000 8 0.55 130 12.7
8-20 LOOSE SAND OR SANDY SOIL 65 4.5 300 2200 35 2.4 30 3.0
15-30 SAND WITH CLAY 100 6.9 200 1450 50 3.5 21 2.0
20-60 WELL-GRADED SAND AND MEDIUM CLAY 180 12.4 110 800 85 5.9 12.5 1.2
20-60 SANDY GRAVEL, CLAYEY GRAVEL OR DRY CLAY 300 20.7 65 480 165 11.4 6.3 0.6
50 AND ABOVE COMPACTED SANDY, CLAYEY GRAVELS N/A N/A N/A N/A 200 13.8 5.2 0.5
*[1] CBR DATA IS GIVEN FOR REFERENCE ONLY. THE CBR OF A MATERIAL WILL VARY, DEPENDING UPON WHETHER IT IS WET OR DRY. FOR EXAMPLE, WET SOIL CAN HAVE A CBR OF 4 OR 5, AND DRY SOIL A CBR OF 40 OR 50.
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SOIL ANALYSIS
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SURFACE SAFE BEARING LOAD LB/SQ IN (KG/SQ CM) APPROXIMATE BEARING AREA REQUIRED
10,000 LB 10000 KG
SQ INCHES SQ FEET SQ METERS
SLATE OR ROCK 230 (16.1) 44 0.3 0.06
CONCRETE 156 (10.9) 64 0.4 0.09
HARD PAN AND COMPACTED GRAVEL OR SAND 138 (9.7) 73 0.5 0.10
COMPACT SAND AND GRAVEL 100 (7) 100 0.7 0.14
GRAVEL, COARSE SAND OR MEDIUM CLAY 62 (4.3) 161 1.1 0.23
LOOSE SAND-GRAVEL MIXTURE 42 (2.9) 238 1.7 0.34
MEDIUM STIFF CLAY 35 (2.5) 286 2.0 0.40
LOOSE SAND 30 (2.1) 333 2.3 0.43
SOFT CLAY OR EARTH 15.5 (1.1) 645 4.5 0.91
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SOIL ANALYSIS
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2-10-4 Manufactured and Prepared Surfaces
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