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Assumptions and values: A slope or retaining wall could fail to ensure stability in any of the following ways: -it may overturn about its toe -it may slide along its base -it may fail due to loss of the bearing capacity of the soil supporting the base (including excessive settlement of the foundation) -it may undergo deep-seated shear failure Bearing capacity of foundation (soil/rock below slope and any retaining wall)3 ksf(shale bedrock in place, undisturbed).' Bearing capacity of driving side (undisturbed soil in slope and behind any retaining wall)3 ksf(gravel and sandy gravel, partial cementing, in place, undisturbed).' Angle of repose, undisturbed material in slopes(cut slopes):50°-cos 4= .6428. sin 4=.7660 . Angle of repose of material placed in slopes(fill slopes):40° (conservative for sandy gravel and cobbles, uncompacted and cohesionless, although all material compacted in lifts)'cos.4=.7660 sin 4=.6428 Angle of repose of drylaid rock(including rock facings):80' Angle of repose for tires/tire bales:90'(vertical), but there will be a slight stepback for two-bale use. Angle of slope(2:1): 26.57`cos 4= .8944 sin zf= .4473 Tire bales: 2,000 lbs(2 kip)2.31 CY. (Standard bale size is 5 x 5 x 2.5 feet. 25 SF footprint) Unit weight of tires/tire bales:866 lbs(0.87 kip)/CY or 32 LCF or 0.87 KCY.ground pressure 80 psf Unit weight of soil-filled tires:460 lbs/ea(typical LT245/701117 is 4 CF)=115 LCF(6 tires 2.6 ft diam,5 ft ht,5.3 SF footprint)or 2.4 KPY.ground pressure 520 psf Unit weight of undisturbed soil:3.24 kip/CY(3.24 KCY)or 120 LCF Unit weight of placed backfill behind retaining wall:80-100 LCF(clean cobbles and gravel(12-inch minus),free draining) Unit weight of drylaid rock wall: 150 LCF(8 ft hig,4 ft x 4 ft),ground pressure 1200 psf Using (coefficient of friction)of rubber on wet shale(equal to rough concrete),stationary µ=0.754,for shale on wet shale (equal to rough concrete) µ=0.85) Surcharge: other than the slope itself(behind any retaining walls),there is negligible loading:fence along the top of the proposed slopes(at property line)and distance from activity centers limits potential live loads due to traffic,and no construction is planned within 25 feet of the property line to the rear of the retaining wall or at the top of any cut or filled slope.Since the county does not allow structures to be built within 25 feet of property lines without approval of the adjacent property owner, it is assumed that no future structure will be built which creates anything other than a negligible surcharge. Water pressure: negligible:with free-draining backfill protected against fine particles infiltrating the material,and freeze-thaw reduced to a minimum by 60 inches of rubber insulation (the tires),water pressure will not build up in the backfill and any water moving through the undisturbed soil behind the retaining wall will be able to flow rather than accumulate. None of the slopes intersect a water table. Based on terrain of creek to north,water table is well below the excavation proposed (10-20 feet). In- place(undisturbed)and compacted soils are free-draining. Resisting-side force is assumed to be zero for overturning and bearing capacity analyses. It is assumed that the 2:1 slopes will consist either of(a) material left undisturbed as the excavation for the new access road is done,or(b) material excavated on-site will be placed as engineered fill(lifts of 1 Source: https:Hup.codes/s/presumptive-load-bearing-values-of-soils z Source: https:Hup.codes/s/presumptive-load-bearing-values-of-soils 3 Source: https:Hstructx.com/Soil_Properties_005.html °https://www.engineeringtoolbox.com/friction-coefficients-d 778.html (2005) s https://www.concreteconstruction.net/how-to/friction-factor-for-concrete-on-concrete o(2018 8th Edition of PCI Design Handbook) Stability Analysis M2011-014 Schmidt Site Page 2 of 3