How to Drive Steel Sheet Pile?

There are three typical sheet pile driving methods.

1. Single Pile Driving Method

From one of corners of sheet pile walls, drive the pile one by one until the end of the project. This method is convenient, fast and does not require auxiliary support, but pile easily incline during driving, and the error accumulation is not easy to correct.

2. Screen-Piling Method

Put 10~20 sheet piles in rows into the leading guide or frame to shape it like a screen wall, then pile driver play back and forth, first drive both ends to the required depth, then pile the middle sheet pile sequentially. This method prevents the sheet pile’s larger inclination by reducing the tilt error accumulation, and easy to close up after construction. But its drawback is that construction process is a bit slow, and need the erection of a higher pile frame.

3. Piling by Waling Piece Method

At a certain height on the ground some distance from the axis, firstly build single or double layers of circle waling pieces as bracing system, then insert sheet piling one by one inside. When four corners are closed up, gradually drive sheet piles block by block in steps’ way to the designed elevation. This approach ensures flat size of sheet pile wall, squareness and flatness, it is suitable for occasions requiring higher precision, fewer pile amounts. The disadvantage is the complexity and slowness in construction, and it requires shaped sheet pile in wall closure.

( Excerpted From Three Typical Sheet Pile Driving Methods  )

Sheet Pile Pit-Retaining Structure Design

Design of  sheet pile retaining structure in foundation pit can be divided into the following three categories:

1. Cantilever Support Structure – when the excavation is not very deep, the cantilever support structure can be used to block soils behind the wall.

2. Single Support Structure – when the excavation depth is larger, to ensure the retaining structure safety and reduce distortion, often set a support or an anchor near the top of the supporting structure.

3. Multi-support Structure – when the excavation depth is large, we can set multi-layers of support or anchors.

Design Contents of Steel Sheet Pile Retaining Structure

1. Select the sheet pile type and model cross-section;

2. Calculate and check sheet pile insertion depth, cross-section strength and deformation;

3. Consider the corresponding precipitation plan and its impact on the surrounding environment (including the vibration impact in pile recycling or removing)

(Excerpted From Steel Sheet Pile Pit-Retaining Structure Design Classification )

Calculation Points on Sheet Pile Wall Structure in Soft Soil Water

1. Three Types of Calculation

A. The whole sheet pile wall structure must meet construction requirements in strength and stablity. In calculation, we should consider the worst construction condition and flowing water pressure from above riverbed to river surface, water foce when ships passing by and in tide situation. Pressure from below the riverbed to sheet pile end is combined by hydrostatic pressur and positive earth pressure.

B.  Because of three layers steel waling system, the whole weight is on the sheet pile, we must calculate the vertical load of sheet pile wall.

C. Because of soft soil with deep excavation, the base of sheet pile wall must do stability calculation mainly including Pile Sand Welling and  Base Bumping Calculation.

2.   Establish Calculation Model

 

Use Infinite softwarelike Midas Civil, sheet pile is modeled or simulated by pile units, support and waling system is simulated by beam units.

3、Notes on Base Stability Calculation

 

3. 1　Pile Sand Welling in Base End Calculation

In the pumping of base end, it easily brings danger of pipe sand welling, we should calculate in simplized way. The rule of calculation is by the enough sheet pile embeded depth t to increase water flow length and reduce upward water force. The frequently used calculation formula for non-sandwelling is : K·i·γ≤γ

In this formula：

K-Safe Coeffcient (less than 2 is required) ;
I—hydraulic gradient;
i = h′/(h1+ t) ;
γ—Water Weight ;
γb —Soil Effective Weight

3.2  Base Bumping Calculation

After deep excavation in soft soil foundation pit, under the water pressure and unbalanced soil pressure inside and outside, there may be bumping situation at the end of soft base,  we can claculation by slip surface way, the frequently used fomula is :

Slip Moment：Md=γMH（x2/2）
Stable Moment：Mr=x∫π/2+α0 SM(xdθ), α＜π/2

In this formula：
α=atg(b/h);
h – the height of bottom inside support against to concrete casting height
b – Haft length of base end;
SM -shear strength without watering in slip surface

Note: the article is from  Calculation Points on Sheet Pile Wall Structure in Soft Soil Water