There are several machines and equipment which are employed for pile driving during construction. These machines and tools will be explained in the following sections.
Fig.1: Pile Driving Equipment
Fig.2: Pile Driving Equipment
Types of Pile Driving Equipments
- Piling rigs
- Piling winches
- Hanging leader
- Hammer guides
- Piling hammer
- Helmet, driving cap, dolly, and packing
It composed of a series of leaders, which are consist of tabular element or hard box, placed and fixed on a crane base as it can be seen from Figure-3.Not only does the leaders support the hammer and the pile but also guide them when the pile is forced into the ground.
Fig.3: Pile Driving Rig
The leader can be sloped forward and backward using screw or hydraulic adjustment and attachment at the base of the equipment as shown in Figure 4 and Figure 5. It is possible to install a series of piles, without the need to move the equipment, through turning around base machine and positioning leaders.
Fig.4: Backward Raked Pile Driving Rig
Fig.5: Forward Raked Pile
Regarding pile installation in water, pile driving rig can be used to install piles in water by placing it on pontoon or leader are fixed on braced frames that mounted on pontoon as shown in Figure-6.
Fig.6: Pile Driver Mounted on Pontoon
Moreover, it is considerably crucial to pay adequate attention to the position and alignment of the leader since any disposition would lead to hammer eccentric blows eventually the pile will be either damages or displace from its original position.
Furthermore, efforts have been made to improve the efficiency of driven pile machine and the Delmag MDT 0802, which possess broad range of adjustments with great movement capacity, is compelling example.
The machine on which Delmag MDY 0801 is fixed on is a wheeled hydraulic excavator that it’s rams provided sideway, forward, and backward sloping leader, in addition to arrange the location of the rig in relation to the equipment.
Finally, not only does the leader operation height can be changed thought leader telescoping but also it could be folded onto the base while the machine it moved from and to the construction site.
Fig.7: Delmag Pile Driving Rig
Fig.8: Pile Driver Rig
The prime goal of piling winches is to left the hammer and piles in addition to support tools that responsible for leader raking and rotation. It functions with pile frames and different powering sources such as hydraulic power, stream; diesel; or petrol engines, and occasionally electric motors could be applied for powering winches.
There are different piling winches with different capacity for instance winches with double or triple drums possess satisfactory controlling and pile driving speed whereas one drum winch does not have that advantage. So, the former type would be favored provided that handing and driving piles with great speed is required.
Hanging leaders are specifically designed to be hanged from the jib of a crane as shown in Figure-9. A steel strut, which its length can be varied as per requirements of construction site, provides a stiff connection from the leader foot to the machine bed frame.
Fig.9: Hanging Leader
Moreover, crane or excavator winch units are utilized to left the hammer and piles using separate drums. Regarding hammer application, either drop hammer with friction winch is considered or it may be operated using stream or hydraulic power or compressed air which are provided by different units.
Finally, it is substantially crucial to practice utmost precaution to hanging leader stiffness particularly in the case of long sloped pile driving since intolerable deformation would lead to eccentric hammer blow and possibly cause pile fracture.
When it is intended to remove hanging leaders or piling frames completely, rope suspended leaders which are commonly guided by timber or steel formwork, would be considered.
In this technique, an independent crane needed to control the pile and establishing the guide and hammer. it is necessary to set and secure the guide properly in order to avoid movements specifically in the during raking pile installation. This is because serious fatigue stress would generate if the thrust is not centered properly and the guide might deteriorate.
Finally, it is required to prevent disproportionate bending stress development in guide and piles because it leads to undesired results. for example, when heavy hammer is attached to the upper end of a long pile which is driven at flat angle of rake, excessive bending stress may be generated at support point in the guide. This problem might be tackled by providing suitable support for the pile at proper position.
Fig.10: Hammer Guided and Rope Suspended Leader for Delmag Diesel Pile Hammer
There are several factors that greatly influence the decision to choose suitable piling hammer. For example, pile size and weight, the resistance of the ground which should be overcame in order to obtain specified penetration, construction site space availability, noise limitation that might be imposed at certain areas, and availability of cranes.
Previously, the combination of a dynamic equation result and extensive experiences were employed to select piling hammer, but this has changed nowadays and drivability analysis results, which is conducted using computer program based on Smith wave equation, is considered for the piling hammer determination.
As for input data required for drivability analysis, piling hammer producer provided necessary data about efficiency and energy feature of the piling hammer. It should be bore in mind that piling hammer efficiency is not a constant and it is affected by number of factor for example mechanical condition of the hammer and operation temperature.
It should be known that the mechanical condition is not influence the efficiency of piling drop hammer. That is why dynamic pile analysis is carried out and its results would be used to assess the influence of different factor on the piling hammer efficiency.
There are various types of piling hammer with different energy characteristic and each is suitable for specific construction condition. different common types of piling along with their description, application, and advantages are provided in Table 1:
Table-1: Different types of hammer piling along with their description, application, advantages, and disadvantages
Drop hammer, Figure 11
|Pile hammer description||Application||Advantages||Disadvantages|
|it is a forged steel with solid mass ranges from 1000 to 5000Kg, and it is fitted with lifting eye and lugs for sliding in the leaders||Applied to install test piles||Its application removes the need to employ steam boiler or air compressor to power the hammer, so it is economical choice||The height of hammer dropping cannot be controlled properly at project site, and it is possible to use substantial dropping when driving becomes tough and hence the pile damage is possible|
Single acting steam or compressed air hammer, Figure 12
|Consist of massive weight ranges from 2500 to 20000Kg with a cylinder shape, and the power source would lift the hammer to specified height then the power is cut to drop the hammer and hit pile helmet. Maximum hammer height is 1.37m and no higher 1.2m in case of heavy pile||Used for placing piles with different weights in different types of soils and suitable for pile installation in marine environment||Drop height and frequency of each drop can be controlled by operator,||Pile fracture is possible is the specified hammer height is exceeded|
Double acting pile hammer, Figure 13
|Double acting pile hammer is powered by steam or compressed and its mass rages from 90 to 2300Kg. Vulcan hammer is an example of double acting hammer. The pile is guided by timber frame.||Applied to install sheet piles and suitable for providing rapid succession of blows. It can be used to demolish rocks for extracting piles||It is specifically designed to impart numerous blows at short time. 300 blows per minute for lightweight hammer and 100 blow/ minute for heavyweight hammer||It is needs maintenance and lubrication|
Diesel pile hammer, Figure 14
|It is powered through self-ignition of compressed fuel and air mixture. There are various types of such hammer with different weights ranges from 4500 to 15000Kg. Lastly, it is considerably reliable type of hammer and different pile types such as sheet pile, batter pile, and H-beams.||It properly drives pile in soft soil condition||It is economical and self-contained. It provides sustained blow which more efficient that ordinary blows||It might damage precast concrete pile when strong layer come up while driving through soft ground It is not suitable for all ground condition.|
Hydraulic operated hammer, Figure 15
|Hydraulic hammer is manufactured in different and large sizes ranges from moderate loading to heavy loading. Hydraulic fluid raises the pile and then release it to fall freely on the pile in addition to have power activated downstroke. Not only can hammer be operated manually but also automatically.||It suitable for piling in land and in water to a depth of 1000m||It creates less noise and vibration compared with diesel hammer and it does not release fumes|
Fig.11: Drop Hammer Operation
Fig.12: Single Acting Hammer Operation
Fig.13: Double Acting Hammer
Fig.14: Diesel Pile Hammer
Fig.15: Hydraulic Operated Hammer
Helmet, Driving Cap, Dolly and Packing
Helmet is a cast steel that placed over the pile to hold the dolly that placed between the pile and the hammer to avoid pile head deterioration that may cause by pile driving hammer.
Dolly, which is square at the bottom and round at the top, is placed in a square recess at the top of the helmet. There are different types of dollies for example Elm dollies, hardwood like oak; greenheart and pyinkado, and their selection is dependent on the driving force.
As far as packing is concerned, it is placed between pile top and the helmet in order to protect the former from the hammer blow. Different types of packing include paper sacking, thin timber sheet, coconut mapping, and sawdust in bags.
Regarding driving cap, it is provided as a protection for steel bearing piles. It is necessary to place the driving cap tightly otherwise the pile cap would suffer deterioration. That is why it is fitted with a recess for hardwood or plastic dolly and with steel wedges to fix the cap tightly on its position.
Lastly, serious pile head damage and hammer breakage cannot be avoided unless appropriate material and suitable thickness is selected for dollies and packing.
Fig.16: Placed Helmet, Driving Cap, Dolly and Packing
Fig.17: Installed Helmet, Dolly and Packing