STEEL SHEET PILES
There is a variety of steel piling plant available on the market to install steel sheet piles. The following tables from the ArcelorMittal Piling Handbook 9th Edition provide useful preliminary guidance on installation methods to consider in predominantly cohesionless and cohesive ground.
Tables 11.2. and 11.3. give guidance on methods to consider for soil types, Table 11.4. takes into account resistance effects from strata thickness. Table 11.5. gives guidance for press-in piling by pitch and drive only. The selection of a suitable pile section for driving into cohesive soil is a complex process and the section choice is often based on previous experience. However it is possible to assess the driving resistance using the surface area of the piling profile and the characteristics of the cohesive strata. The following table may be used for preliminary assessment.
|SPT value||Vibro drive||Impact drive||Press-in singles|
|0 -10||Very easy||Runaway problem|
=> use vibro method
to grip pile
|Stability problem &|
|10 - 20||Easy||Easy||Suitable|
|21 - 30||Suitable||Suitable||Suitable|
|31 - 40||Suitable||Suitable||Difficult => consider pre-auger|
|41 - 50||Very difficult => consider pre-auger||Suitable => consider HYS||Difficult => consider pre-auger or|
|Suitable => require HYS||Very difficult|
=> crush piler required
HYS: High Yield Strength Steel
Table 11.2. Driving in coarse soils or predominantly cohesionless ground.
|Cᵤ value (kPa)||Vibro drive||Impact drive||Press-in|
|0 - 15||Easy||Runaway problem => use vibro method|
to grip pile
|Possible stability problem|
& insufficient reaction
|16 - 25||Suitable||Easy||Easy|
|26 - 50||Becoming less effective|
|51 - 75||Very difficult||Normal||Normal|
|76 - 100||Not recommended||Suitable => drive in pairs||Difficult|
|100+||Not recommended||Suitable => essential to drive|
|Difficult => consider ground|
pretreatment or jetting
Table 11.3. Driving in cohesive strata.
It is rare to have a site where the ground is classified as wholly cohesionless or wholly cohesive and hence the selection of plant must be a compromise, choosing plant suited to the dominant soil type but also considering the ability of the plant to penetrate the other soil type. The final selection of driving plant and section size for economical pile installation is often based on previous experience. It is recommended that advice is sort from an experienced steel piling contractor.
Further tables and explanation on driveability are also provided in the ArcelorMittal Piling Handbook 9th Edition.
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Steel Piling Group, C/O SCI, Silwood Park, Unit D, Buckhurst Road, Ascot ,Berkshire. SL5 7QN