Driving sheet pile

[brokenpile]

We are driving PZC 13 sheets with vibro hammer in the Newark Bay along the Bayonne shore line.Owners enginner specified a 25 foot long sheet.Then we have to drill grouted 2" hollow bar tie backs at 30 degrees ,60 ft long.As we drive the sheets the others that are set to grade are sinking several inches.Sheets are exposed 9 feet with 16 feet in the ground,with little to no refusal what so ever.We feel that they need a 50 foot sheet with refusal,enginner says its not a concern but if the sheets sink won't they pull the tie back anchors down also and cause failure ?Sheet pile is being driven in front of a concrete seawall which sets on old rotted wood pilings that are failing.Once sheets are set we have to pour concrete between sheet pile and under seawall to support it,so engineer states thats the sheet pile is just a concrete form at this point.Is the owners engineer a loon or what ??? Mind you we fought for months with engineer due to his requirement that we had to have 7 kips on the waler when 4.5 kips was more then you would ever need.

 

[civilperson]

Why fight with the designer? Just provide what was specified and as you bid it. Any lacks or failures will not be laid at your feet!

 

[DRC1]

This is not an uncommon occurance on soft ground. As you vibrate the sheets, the other interlocked piles will vibrate and begin to settle. Once the driving is done, the wall friction is restored and the sheets should be stable. To combat the problem, the sheets are generally tacked to the previous sheet so that individual sheets can not settle. Otherwise you wil have to come back and reset the sheets after you have driven away from them several sheets.
One concern about settlement is the angle of the tie back. The sine of the angle of the tie back times the load in the tie back wiil be transfered to the wall as vertical load. The wall should be checked to be sure it will support that load. Generally this is not a problem, but in softer marine soils it can be. Unless you are tring to miss obstructions, the angle can usually be flattened to 15 degrees, and still be groutable. Check with your installer first, and obviously dicuss with the engineer.

 

[brokenpile]

angle of tie back is 30 degrees and 60 long to hit the good material below.We drove two master piles in down to 50 feet and around 40 feet we hit good material and the hammer had to work.We are also welding the other sheets together.Next step seems to be to weld clips to the sheets and anchor bolt them to the exsiting concrete wall to hold the sheets up.