Foundation Engineering & Design
Foundation engineering is a critical branch of civil engineering focused on designing and analysing the foundation systems that support structures such as buildings, bridges, dams, and other infrastructure projects. Atlas Engineering and Technology Group (AETG) understand that the role of foundation engineering is to ensure that the structure's load is transferred safely to the underlying soil or rock strata, preventing settlement, tilting, or failure over time. The design of structural foundations is heavily dependent on the soil properties, the type of structure being supported, and the environmental conditions of the site.
AETG Foundation Engineering Services:
Soil Investigation: Before designing any foundation, a thorough site investigation is conducted by AETG to assess the soil’s properties, including soil type, shear strength, bearing capacity, moisture content, and compaction characteristics. Boreholes and soil samples are obtained from the site to perform laboratory tests in AETG's NATA accredited laboratory, and perform field tests such as Standard Penetration Test (SPT), Cone Penetration Test (CPT), Dynamic Cone Penetrometer (DCP) and laboratory soil tests (e.g., Atterberg limits, grain size distribution). The investigation helps determine the bearing capacity of the soil, which is crucial for designing the foundation.
Bearing Capacity: The bearing capacity refers to the maximum load per unit area that the soil can safely support without failure. The foundation design must ensure that the loads transferred to the soil do not exceed its bearing capacity, preventing settlement or shear failure. There are different methods to calculate bearing capacity based on soil type, including Terzaghi’s bearing capacity equation, Meyerhof’s method, and Prandtl’s method for cohesive and granular soils.
Types of Foundations: Foundations can be classified into two primary types: Shallow foundations and Deep foundations.
Shallow Foundations
Shallow foundations are typically used when the soil near the surface has adequate bearing capacity to support the loads of the structure. They are constructed at relatively shallow depths, typically within 3 to 4 meters from the ground surface.
Types of Shallow Foundations:
Spread Footings: A spread footing (or isolated footing) is a type of shallow foundation where the load from the superstructure is spread over a larger area to reduce pressure on the underlying soil. This type of foundation is used when the soil beneath is competent and the load-bearing capacity is adequate. Spread footings can be square, rectangular, or circular, depending on the structure's layout and load distribution.
Slab-on-Grade Foundations: This is a flat concrete slab placed directly on the ground. The slab is designed to carry loads and distribute them evenly over a large area. Slab-on-grade foundations are commonly used in residential construction and for light structures. These foundations are ideal for sites with stable soils, but they may not be suitable for expansive soils that shrink or swell with moisture changes.
Strip Footings: A strip footing is a continuous strip of concrete designed to support walls. It is usually employed when walls are aligned in a straight line and the load is distributed along the entire length of the wall. This type of foundation is often used for low-rise buildings with moderate loads.
Mat or Raft Foundations: A raft foundation (or mat foundation) is a large slab of concrete that extends across the entire footprint of the structure. It is typically used when the soil's bearing capacity is low or when there are large, concentrated loads. This foundation type can distribute the load of the building over a large area, minimizing the risk of excessive settlement.
Deep Foundations
Deep foundations are used when the upper soil layers do not provide sufficient strength to support the load of the structure. In such cases, the foundation needs to reach deeper, more stable layers of soil or bedrock to transfer the load. Deep foundations are used for high-rise buildings, bridges, and other heavy structures.
Types of Deep Foundations:
Pile Foundations: Piles are long, slender columns made of steel, concrete, or timber that are driven or bored deep into the ground to transfer the structure's load to deeper, more stable soil or rock layers. End-bearing piles transfer the load to the underlying rock or firm soil, while friction piles rely on the friction between the pile surface and the surrounding soil to support the load. Piles are commonly used in areas with soft or loose surface soils, or in marine environments where deep foundations are necessary due to water levels.
Drilled Shafts (Caissons): Drilled shafts, also known as caissons, are large-diameter concrete columns that are drilled into the ground to support heavy structures. The shaft is drilled until it reaches a stable layer of soil or bedrock, and then filled with concrete. This type of deep foundation design is suitable for locations where piles cannot be used, such as sites with high groundwater or sensitive structures.
Bored Piles: Bored piles are drilled into the ground and filled with concrete or reinforced concrete to create deep foundations. They are similar to drilled shafts but are often used in smaller-scale applications and can support lighter loads.
Why Choose AETG for Foundation Engineering
AETG understand that foundation engineering and design play a vital role in ensuring the stability, safety, and durability of structures. By considering factors such as soil properties, load distribution, settlement, groundwater conditions, and seismic activity, our engineers can design foundations that will provide secure support for structures. The design process involves selecting the appropriate foundation type (shallow or deep), performing stability and settlement analyses, and incorporating proper drainage and waterproofing measures in accordance with relevant Australian Standards (AS2870, AS3600, AS5100 and AS1289). Whether using spread footings, piles, or caissons, careful consideration and design will ensure that the foundation meets the engineering requirements and the project's specific demands and needs. Contact AETG today to see how we can help with your project needs.
Successfully Completed Jobs by AETG to Date
✔ Proposed Foundation Assessment - William Lawson Dr, Prospect NSW
The report AETG produced contained a bearing capacity assessment of a site located at William Lawson Dr, Prospect, intended for the construction of a 4-level basement. Subsurface conditions were assessed through borehole drilling and laboratory testing, revealing fill material overlying Coode Island Silt and Silurian bedrock. The report identifies the rock at depth as suitable for founding structures, recommending socketed bored piles or barrettes for high axial load-bearing elements, with ultimate shaft adhesion values up to 750 kPa and base bearing values up to 15 MPa, depending on depth and socket length. The report also considers groundwater conditions, construction methods, and lateral earth pressures, offering design parameters for temporary and permanent works while emphasising the importance of site-specific verification during construction.
✔ Proposed Primary School Upgrade - Our Lady Queen of Peace Primary School, Greystanes
Based on the Bearing Capacity Report for the Our Lady Queen of Peace Primary School project in Greystanes, NSW, AETG conducted a foundation assessment to evaluate the suitability of subgrade soils for supporting proposed pad footings and a raft slab. The investigation included on-site Dynamic Cone Penetrometer (DCP) testing, visual and tactile inspections, and reference to structural design information.
The primary focus was to verify that the founding materials could achieve Allowable Bearing Pressures (ABP) of 120 kPa for pad footings and 60 kPa for the raft slab. DCP results showed a stiff silty clay profile with sufficient strength characteristics, including a friction angle of 26°, unit weight of 18 kN/m³, and effective cohesion of 5 kPa. The soil was classified to fail under a general shear failure mode, which is preferred for stable footing performance.
While most locations satisfied design criteria, four locations required additional excavation to a minimum depth of 600 mm below ground level to meet stability requirements. Over-excavated zones are to be reinstated with mass concrete matching the foundation design. The report emphasised that all loose and wet material must be removed before concrete pouring to ensure long-term performance and structural integrity.
Overall, the foundation conditions were deemed suitable for the proposed structural loads, contingent upon the above recommendations being followed during construction.
✔ Proposed Infrastructure Upgrade - Abbotts Rd, Kemps Creek NSW
The foundation assessment for the proposed manhole at Abbotts Road, Kemps Creek, conducted by AETG, confirmed that the site is underlain by Class IV Bringelly Shale—a grey, highly weathered, low-strength rock with traces of iron induration. This assessment was based on a visual inspection as part of the Proposed Infrastructure Upgrade project for Ardee Civil Pty Ltd. The manhole was designed to require an Allowable Bearing Pressure (ABP) of 150 kPa, and the observed bedrock was determined to meet or exceed this requirement. AGS emphasised that all loose or deleterious materials must be removed from the excavation base before concrete placement to ensure structural integrity. The findings support the adequacy of the foundation material for the proposed load, assuming the excavation is properly cleaned and maintained, especially after adverse weather conditions.