Ground Structures offers extensive knowledge and experience for a broad range of piling solutions including bored concrete and timber/steel piles and driven pile options. Utilising a range of excavators up to 33 tonne mounted with pendulum drilling rigs, we are capable of reaching founding depths of 18m for residential, commercial and infrastructure construction. Pendulum drilling rigs have extended reach and are ideal for drilling piles that are beyond the capability of fixed mast drilling machines. We offer the capability to work in difficult access areas, in a range of geotechnical environments and challenging site conditions. All materials to complete necessary works are provided as required.
Irrespective of the piling solution required, we offer a single source solution which may include construction of retaining walls, foundations, slip repairs and stabilisation, site works and civil structures.
Bored Reinforced Concrete Piles
Bored, cast insitu reinforced concrete piles are used to support structures which produce heavy vertical loads. Piles of variable lengths can be drilled through soft or expansive soil into suitable load bearing material. Bored piles are used for building and structures, underpinning existing structures, and palisade, soldier pile and contiguous retaining walls. They offer some advantages over other piling methods or footings, depending on the engineering specifications, as they provide for higher load-bearing capacities, and minimise vibration and noise level. Adjacent piles, ground or other structures are not disturbed and large excavations and backfill are unnecessary, which is particularly important in conservation or environmentally sensitive sites. Depending on soil conditions, boreholes can be supported by temporary or permanent casings (caissons), which can be installed in advance of drilling works using casing drivers or vibratory hammers. Bored piles can also be belled or grooved to increase loading capacity.
Drilled and Concreted Timber/Steel Piles
Encased piles are constructed with timber poles or steel sections embedded and encased with concrete. Concrete encasement provides additional strength to timber and corrosion protection to steel piles.
Palisade Timber or Concrete Piles
Palisade timber or concrete piles are used in the construction of highly effective permanent piling solutions. Typically for heavy duty applications supporting substantial loads, palisade walls are also known as inground or barrier pile walls. They are often constructed with a concrete capping beam and are an effective measure to preserve or remediate cliff erosion and arrest the effects of ground subsidence. It is not uncommon for piles of this nature to be completely buried.
Soldier piles, or barrier pile walls utilise either encased timber or reinforced concrete piles, are closely spaced and penetrate into more competent subsoils, thereby retaining the more unstable upper layers. Often a capping beam is used to link the piles, or used in conjunction with house piles to ensure stable ground support.
Pole foundations can be drilled and concreted or driven, and provide for both lateral and vertical support, typically for lighter structures such as residential properties, decks, suspended car decks and timber bridges.
Driven Piles/Pile Driving
Driven piles are driven to a design depth or resistance and may include timber, pre-cast concrete, steel H piles, and pipe piles, installed using an excavator mounted drop hammer. If penetration of dense soil is required, predrilling may be required for the pile to penetrate to the design depth, however generally they are displacement piles, which provide for a quick cost-effective solution, with no spoil removal, and can be used in wet soil conditions with geotechnical limitations, or as a temporary piling solution.
Steel sheet piles are long structural sections, which vary in size depending on the application, with a vertical interlocking system that creates a continuous wall, and are often used to retain either soil or water.
Underpinning is the process of strengthening the foundation of an existing building or other structure – it extends the foundation in depth or breadth so it either rests on a more supportive soil base or distributes its load across a greater area. Micropiling is a common method in underpinning.
Underpinning may be necessary for a number of reasons – the original foundation is not strong or stable enough, the use of the existing structure has changed necessitating an increase in the depth or load capacity of existing foundations, the properties of the soil supporting the foundation may have changed (possibly through subsidence), or the construction of nearby structures requires the excavation of soil supporting existing foundations. Earthquake, flood, drought or other natural causes may have caused the structure to move, thereby requiring stabilisation of foundation soils and/or footings.
Micropiles, also called mini piles, are made of steel with various diameters from approximately 60 to 200mm, and are often used for underpinning existing piles in various project applications by creating a deep foundation element using high-strength, small-diameter steel casings and/or threaded bars which can be raked if required. Typically, smaller diameter excavator mounted drilling equipment is used, which creates minimal vibration during installation, therefore micropiling applications are particularly useful at environmentally sensitive sites, or those with difficult, restricted or low access, for example, residential homes and basements. Micro piling is typically used as a temporary or permanent measure to remediate existing foundations and seismic retrofitting or strengthening.
Tie Backs and Anchoring to Piles and Retaining Walls
A tieback is a horizontal wire or rod, used to reinforce retaining walls for stability. With one end of the tieback secured to the wall, the other end is anchored to a stable structure, such as a concrete deadman pile which has been installed into the ground or anchored into earth with sufficient resistance. This application reduces the loading on the main structure by transferring the load to the deadman pile which can be located on more competent ground, thereby resisting forces that would otherwise cause the wall to lean. Deadman piles are retrofitted to both existing walls, and used in new wall construction to transfer loads back to more competent ground away from the main structure. This can be an economical solution, rather than completely replacing an existing structure.
Temporary Retaining Piles
Temporary retaining piles are used as a means of temporary stabilisation of soil in unstable ground conditions. Temporary and permanent steel casings are used for bore hole support, using casing drivers or vibrators. Temporary retaining piles may include timber, steel UC posts either driven or drilled and concreted.
Concrete Ground Beams and Capping Beams
Capping beams for piles transfer loads from closely spaced piles into a row of piles to link the row of piles together – they perform the same functions as pile caps. Ground beams are structural elements to connect adjacent pile caps to improve the stability of foundations.