SS Pile and also known as Super Strength Pile has higher strength to carry higher loads of building with lesser pile point, it saves the cost and more economic. Contractor like to use this piling method on those high building and large structure. There is few steps to install or drive the SS piles, it’s economic piling method but it takes time to install as well. Every types of piles have their own pile driving procedure, so the pile driving method is slight different compare with the piling driving procedure for normal spun pile or bored pile. Piling machine used is different as well.

How To Install Super Strength Pile or SS Pile

1) Driving of Piles
Place the cushion, helmet and gammer on the pile head with adequate alignment. Check verticality of the pile to BS 8004 requirements. After several blows, check pile location and alignment again. Concentricity of driving equipment and pile shall be maintained at all times.

When driving to soft ground, adjust the hammer drop so as not to induce excessive tensile stress in the pile. Driving should proceed without interruption until the pile reaches the expected depth or blow count (ie. penetration mm/10 blows).

2) Joint Welding
When a pile has been driven close to the ground level and an extension is required, the driving must be immediately stopped. Joint plates are to be cleaned thoroughly from mud, dust, oil and other residues detrimental to the welding. Cleaning can be done by using wire brush and some solvents in between runs of weld.

Three guide plates at 120 angle to each other are set up on the driven pile before the extension pile is being lowered to sit concentrically over it. The two piles will be alligned automatically. Welders should be qualified to BS 4872 welding test.

Welding is performed by means of either manual or semi-automatic arc welding. For manual welding, electrodes should be selected carefully and conform to type E41 of BS 5135 as a minimum or higher if deemed necessary. Semi-automatic welding should be non-gas shield arc welding.

Throat depth should be filled with more than two layers of welding materials and slag removed in between layers. Metal oxide paint can be applied as an anticorrosion measure. The welding must be checked before driving proceeds.

3) Driving Equipment
SS Piles are usually installed by percussion method. In certain cases where underground obstructions such as large boulders are encountered, special shoes (i.e. conical, oslo point or pipe shoe) or pre-augering may be necessary. The driving hammer type (hydraulic or diesel) and size must be carefully selected to install the piles successfully without any damage to the pile itself (BS 8004). Two plumb guides at right angles to each other are normally used to ensure verticality of the pile during driving. Spirit levels and theodolites have also been proven useful.

4) Helmet and Cushioning
Correct helmet dimensions is critical in curbing the vibration and/or movement of the pile head hence maintaining fixity and eccentricity of hammer to pile.

The inner diameter of the helmet should have a small but not larger than 30mm clearance over the outside diameter of the pile which needs to be wedged tight. The hammer ram must be kept concentric with the pile head to minimize secondary stresses arising from the piling activity.

Adequate timber cushioning is also very significant as it ensures uniform transmission of driving energy. Thickness of cushion is a minimum of 100mm for hard wood for 300mm Ø to 400mm Ø piles and a minimum of 150mm for larger sizes. Since stiffness of the cushioning material increases with repeated compaction.

5) Set Criterion
A pile is considered set when the calculated set criterion is met (penetration mm/10blows) or the required penetration depth reached. Bearing capacity of the pile can then be further checked with a load test after
the pore water pressure has dissipated. PDA and driving formulae checks are also useful.

6) Pile Head Preparation

Piles should be cut using a diamond cutter. Hacking is not recommended as it will generate micro cracks in the concrete. Pile Anchorage Details show suggested anchorage reinforcement. However, reinforcement may be redesigned to cater for individual project specifications.

There is many different type of piles in the market, every type of piles has their own procedure of pile driving. Many contractors are not expert in how to drive a pile or procedure of pile driving. Here is a rough procedure on how to drive a pile. Before the piling process is carrying on, soil investigation have to be carried on, so that piling contractor knows what is the condition of soil. If it’s normal soil then the normal piling procedure can be carried on, but if the soil contains rock or stone, another piling procedure will be carried on. The cost for that also will be affected.

Procedure Of How To Drive A Pile

1) Mob Or Bringing Piling Machine To The Site
Firstly, clarify the location that the piling machine has to be moved to. After that, the piling machine will be moving in to the location in site. The piling machine will be set on place.

2) Driving Initial Pile
After bringing in the piling machine, first pile or starter pile or initial pile will be ready to drive in to the ground by following the pile point that shown in the construction drawing. The initial pile will be driven in to the ground until maximum or can’t be driving in anymore.

3) Driving Extension Pile
If initial pile has been fully driving in to the ground, the second pile or extension pile will be jointing to the initial pile and drive again. The extension pile will be driving into the ground until maximum as the initial pile.

4) Cutting Off Pile Head
Let’s say the 6 metres extension pile has been driving in to the round 3 metres depth only and can’t be driving in anymore. The excessive of 3 metres extension pile will be cutting off.

5) Preparation Of Pile Head Or Pilecap
After cutting off the excessive pile, excavate the soil surrounding of the pile about 300mm depth for preparation of pilecap.

6) Load Test
The purpose of load test is to test the strength of the pile. A certain load will be putting on the pile for a certain period. If the concrete pile is crack, which mean the concrete pile is failed to support the load. If the concrete pile left for certain days without any crack, which mean the concrete pile is strong enough to carry the load of the building. Normally load test will be carried on before driving the pile to the ground. If the load test for the concrete pile is failed, then the contractor has to supply another batch of concrete piles.