Bearing Capacity Verification

Bearing capacity verification is the process of assessing whether the ground beneath a structure is capable of carrying the applied loads without compromising the stability and safety of the foundation. At Atlas Engineering and Technology Group (AETG) we understand that this verification is crucial to ensure that the foundation is designed adequately and in accordance with Australian Standards (AS2870) and that the soil will not fail under the loads applied by the structure, to ensure the integrity of the project.

Methods AETG Use to Assess Bearing Capacity

In-situ tests are carried out on-site to measure the properties of the soil under natural conditions. These tests give a more accurate picture of the soil’s behaviour and bearing capacity ability. Some common in-situ tests include:

  • Dynamic Cone Penetrometer Test (DCP): The DCP test is a field procedure used to assess soil load capacity, strength and subsurface consistency by measuring the resistance to penetration of a cone into the ground. The number of blows required to drive the cone a specific distance is recorded. The number of blows is used to calculate the soil’s strength and bearing capacity. The DCP test is a valuable, efficient, and low-cost method to assess soil strength, allowable bearing pressures and soil consistency. Geotechnical engineers can gather important data to inform foundation design and other construction decisions to meet compliance requirements.
  • Standard Penetration Test (SPT): A split-spoon sampler is driven into the ground at regular intervals, and the number of blows required to drive it a specific distance is recorded. The number of blows (SPT-N value) is used to estimate the soil’s strength and bearing capacity. The SPT-N value is often correlated with the soil bearing capacity and associated soil strength parameters. The value can also be used with empirical equations to estimate the ultimate bearing capacity.
  • Cone Penetration Test (CPT): A cone is pushed into the ground at a constant rate while measuring the resistance to penetration. The tip resistance and sleeve friction are recorded to determine the soil’s strength characteristics. CPT provides more continuous data compared to the SPT and can be used to assess the soil's bearing capacity more accurately, particularly in granular soils.
  • Plate Load Test: A plate is placed at the foundation depth, and loads are applied incrementally. The settlement corresponding to each load increment is measured. The results provide an empirical relationship between load and settlement, which can be used to determine the ultimate bearing capacity and the expected settlement of the foundation.
  • Numerical Modelling and Finite Element Analysis (FEA): Numerical modelling methods such as FEA can be used to simulate the behaviour of the soil under applied loads and predict bearing capacity. These methods are more complex and can model non-linear soil behaviour, varying boundary conditions, and large settlements that might not be captured by simpler analytical methods.

Why Choose AETG for Bearing Capacity Assessments

We understand that bearing capacity testing is a critical part of foundation design and construction. It ensures that the subsurface soils can safely support the applied loads from the structure without experiencing excessive settlement or failure. Foundation bearing verification can be performed through theoretical calculations, in-situ testing, laboratory analysis, and advanced numerical modelling. The method used, often depends on site conditions, the type of foundation, and the available resources. Regular bearing capacity assessments help ensure the stability and safety of the foundation throughout the life of the structure.

Successfully Completed Jobs by AETG to Date

✔ Proposed Childcare Centre - Richard Road, Leppington NSW

AETG conducted a bearing capacity assessment for a proposed childcare centre in Leppington, NSW. The assessment included an on-site assessment, a Dynamic Cone Penetrometer (DCP) test, and client advice. The client advised leveling the subgrade to achieve an Allowable Bearing Pressure (ABP) of 150 kPa. The findings indicate that the founding material underlying the proposed slab on ground location satisfies the required ABP of 150 kPa with respective dimensions. The report is issued on the proviso that the observed DGB fill layer has been compacted prior to concrete pour.

✔ Proposed Culvert Upgrade - Riverpark Drive, Liverpool NSW 

AETG was hired by Transport for NSW to assess the bearing capacity of a proposed stormwater pit in Liverpool, NSW. The assessment was based on on-site testing using a Dynamic Cone Penetrometer (DCP), which determined that the sandy gravel fill material met the design requirement of 150 kPa Allowable Bearing Pressure (ABP). The report assumes that the fill material was placed and compacted properly.

✔ Proposed Telecommunication Monopole Construction - Beech Road, Casula NSW

AETG conducted a bearing capacity assessment for the construction of a monopole at Beech Rd, Casula NSW 2170. The assessment revealed that the foundation was excavated into shale bedrock, which varied in depth from 0.2 m to 0.8 m below ground level. The bedrock was overlain by compacted silty clay and silty clay fill material.

The excavation uncovered that the bedrock was shallower than expected, but the required foundation depth of 1.5 m below ground level was achieved by excavating into the shale. The assessment is based on visual inspection, client correspondence, and supplied documentation, and confirms that the founding material satisfies the design requirement of 1500 kPa Allowable Bearing Pressure (ABP). Any over-excavated material must be reinstated with high tensile concrete.