Design of Sheet Pile Wall

[newbuilder]

Dear All Fellow Engineers,<br><br>I have a little problem with which you may be able to offer some advice.&nbsp;&nbsp;We are looking at the design of a simple sheetpile retaining wall about 5m deep and with two layers of struts in loose sand.<br><br>The designer has adopted the Peck charts for earth pressure.&nbsp;&nbsp;The engineer has disagreed and requested a triangular earth pressure distribution.<br><br>Every book I have checked appears to contradict the other on the use of Pecks charts for shallow excavations.&nbsp;&nbsp;To compound the problem the excavation has been opened and withstood the most severe weather conditions over 6 weeks.<br><br>Can anybody shed any light on the appropriate use of strutted earth pressure charts without recommending I buy more textbooks.<br><br>Regards<br><br>Newbuilder

 

[Ginger]

The Peck envelopes (rectangular for sand) are really for the analysis of braced excavations ie trenches and smaller cofferdams which are relatively deep.&nbsp;&nbsp;If you use this analysis then the loads on the props must be pro-rata to the length of pile that they are supporting (when you look at a cross section). This will give you a conservative prop design as the Peck charts are empirically based on a range of observations. The chart is designed to cover the possible range of loads that the props may carry at depth.&nbsp;&nbsp;The sheet piles should be designed as simply supported beams between the props and there is no allowance for any resistance from toe in of the piles below formation so the sheets below the bottom prop should be designed as cantilevers.<br><br>Generally, for a single sided retaining wall with props, the classic method of analysis is to use a Rankine (triangular) earth pressure and design the wall based on a fixed or pinned toe in of the sheets into the ground.<br><br>However, when one stands back and looks at the problem, the likelyhood is that the Peck method will work provided you have followed the design rules for props and sheets.&nbsp;&nbsp;You can, in theory, argue that you have actually designed one half of a wide trench!!&nbsp;&nbsp;I would regularly inspect the toe of the sheets to check for movement, piping and boiling if the phreatic surface of the retained sand is above formation level.<br><br>Best regards <p>Andy Machon<br><a href=mailto:Andy@machona.freeserve.co.uk>Andy@machona.freeserve.co.uk</a><br><a href= > </a><br>

 

[Ginger]

By the way, a second thought has occurred to me.&nbsp;&nbsp;If this is temporary works then Peck will be OK in the short term.&nbsp;&nbsp;If this is for permanent works then listen to the Engineer.<br><br>Regards<br><br> <p>Andy Machon<br><a href=mailto:Andy@machona.freeserve.co.uk>Andy@machona.freeserve.co.uk</a><br><a href= > </a><br>

 

[newbuilder]

It is temporary works.<br><br>Thanks for the advice.<br><br>rkp

 

[RAY72]

Check this site out.......Ray<br><br><br><A HREF="

http://geotech.civen.okstate.edu/ejge/ppr9601/retwall.htm#Retaining"

TARGET="_new">

http://geotech.civen.okstate.edu/ejge/ppr9601/retwall.htm#Retaining</A>

Wall Design<br><br>also <A HREF="

http://www.ggsd.com/"

TARGET="_new">

http://www.ggsd.com/</A><br><br>