soldier piles with wood lagging 3

[IYIeI2cY]

Hello all,

I need to design a flexibile retaining wall (soldier piles with wood lagging), all the text books i have do not proper handling of this issue, just some formula in very basic situations and wihout solved examples.

Can any one tell me how can i find solved examples for that issue?

My problem is i need to excavate for about 4 meters, i will use I beams verticaly every 2.4 or 3 meters, with wood sections as horizontal elements. the first 2 meters of the soil are sand, then clay, the water table level is in the middle of sand layer.

Fast help is appreciated.

 

[DRC1]

There is not a ton of literature on the topic. For fast help, go to SlideRuleEra's website ( it is listed in his posts in the geo tech forums)It deals with steel sheeting design, but much of the design method is somewhat the same. I believe Vulcanhammer's website has the pdf of te late 70's manual from FHWA by Zoino et.al. That gives more specifics on the design of soldier piles. The Army Corp of Engineers has all their manuals on te web including earth retention. California Transportation Department has a good earth retenion manual online.

Prior to excavating you will need to dewater as soldier piles are difficult to use below the water table.

That said, sheeting and soldier piles are not something you can simply look up fill in a few equations and have a design. More so than with other types of work, the design and construction are connected and good design requires some experience. I would encourage you to work with or at least have a review by an engineered experienced in sheeting design.

 

[DirtJockey]

My suggestion would be to look through AASHTO's manual for highway design, as everything is parametrically listed (in Chapter 3 or 4, I believe), which deals with retaining structures and foundations. Depending on your loads, and the spacing between soldier piles, you can better determine what your design will be. This is good in a general, cookbook sense.

HOWEVER... you have a groundwater problem which will need to be addressed. I understand you will be excavating below the sand (and the groundwater table), and about a meter into the clay. Depending on:
(1) the thickness of the clay;
(2) the width of your excavation;
(3) how you plan to handle the potential hydrostatic pressure on the back side of the wall,

Since you will be excavating below the groundwater table, and depending if you consider seepage effects, your wall may act as an impermeable boundary, and cause a difference in hydrostatic head. The thickness of the clay below the bottom of your excavation, as well as the width of your excavation, will need to be considered for determining if the soil "plug" will blow because of heave at the bottom.

The AASHTO guideline will only serve as an outline for design, but will not take these things into consideration. Your design will need to include provisions for dewatering behind the wall, to install the lagging and (depending on the duration the wall will be in service) handle hydrostatic pressures.

Hope it helps,

Gary Marcus, PE
New York City, NY