# Sheet Piling

## Quiz Questions

 1. Cantilever sheet piling walls depend on the passive resisting capacity of the soil below the depth of excavation to prevent overturning. True False 2. The depth of sheet piling walls below the bottom of the excavation are irrelevant to difference between the passive and active pressures acting on the wall. True False 3. The theoretical depth of pile penetration below the depth of excavation is obtained by Equating horizontal forces and by Taking moments about an assumed bottom of piling. All of the above 4. The theoretical depth of penetration represents the point of rotation of the piling. True False 5. Computed piling depths are generally increased 20% to 40% to obtain some fixity and to prevent lateral movement at the bottom of the piling. True False 6. The cohesive value of clay adjacent to sheet pile walls approaches zero with the passage of time. Design and analysis for clay soil conditions must generally meet the conditions of cohesionless soil design if the sheet piling support system is to be in use for more than a month. True False 7. It is possible to have negative pressure values with cohesive soils. Since cohesive soil adjacent to sheet pile walls loses its effective cohesion with the passage of time it is recommended that negative values be ignored. Do not use negative pressure values for the analysis of sheet piling systems. Any theoretical negative values should be converted to zero. True False 8. The friction value at the soil-wall interface, or adhesion between the clay and the wall, should be ignored with sheet piling walls when the walls are in close proximity to pile driving or other vibratory operations – including functional railroad tracks. True False 9. The stability of cantilever steel sheet pile walls will need to be considered in cohesive soils. The sheetpiling will fail if this height is exceeded. True False 10. When rakers are supported on the ground the allowable soil bearing capacity for the raker footing must be considered. Cohesionless soil having small internal friction angles will have lower soil bearing capacity. Additionally, when the footings are sloped relative to the ground surface reduced soil bearing capacities will result. True False 11. The safety factor of 3 for footings recommended by NAVFAC is generally considered to be for permanent installations. For short term shoring conditions a safety factor of 2 might be used. A reduced safety factor, however, could allow greater soil settlement, which in turn would permit additional outward wall rotation. Therefore, when wall deflection or rotation is not deemed critical a safety factor of 2 may be used for short term conditions. True False