Soil Testing & Site Classifications

The Soil Testing Report service at Brisbane, Gold Coast, Sunshine Coast The soil testing and site classification are one of the most important aspects of the construction of any new buildings and extensions. The Australian standard AS-2870 Residential slabs and footings require that all the foundations be designed according to the soil test results and site classification.
Several issues may arise if the footings are not designed for the correct classification of soil. It is highly recommended carrying out soil testing before signing any building contract as the foundation design can significantly affect the cost of the project. SNG Engineers ensure that the foundations are designed according to the correct classification of soil.

SOIL TEST PROCEDURE

A minimum of two boreholes or test holes is drilled to a depth of 2m using a truck-mounted power auger or hand auger depending on the access to the site. A Dynamic Cone Penetrometer or Pocket Penetrometer is used to identify the bearing capacity of the founding soil. The soil is then classified at a range of depths by their different types. The samples of the soil are taken for laboratory testing to identify the reactivity of the soil. Other characteristics of the site are also noted including a water table, existing vegetation, drainage, slopes etc. From the site and laboratory results, a soil test report is prepared for the engineers to prepare foundation design.
However, the site may be classified as P due to other factors such as the low bearing strength of soil, potential excessive foundation settlement, fill, mine subsidence, land-slip, collapse activity, coastal erosion, abnormal moisture changes or sites which cannot be classified otherwise.

SOIL V/S SITE CLASSIFICATION

The soil is usually classified according to the below table according to AS-2870.

Class ‘A’ Soil – Mostly sand and rock sites with little or no ground movement from moisture changes.

Class ‘S’ Soil – Slightly reactive clay sites, which may experience only slight ground movement from moisture changes. Estimated characteristic surface movement, 0 < Ys ≤ 20mm.

Class ‘M’ Soil – Moderately reactive clay or silt sites, which may experience moderate ground movement from moisture changes. Estimated characteristic surface movement, 20 < Ys ≤ 40 mm.

Class ‘H1’ Soil – Highly reactive clay sites, which may experience high ground movement from moisture changes. Estimated characteristic surface movement, 40 < Ys ≤ 60 mm.

Class ‘H2’ Soil – Highly reactive clay sites, which may experience very high ground movement from moisture changes. Estimated characteristic surface movement, 60 < Ys ≤ 75mm.

Class ‘E’ Soil – Extremely reactive sites, which may experience extreme ground movement from moisture changes. Estimated characteristic surface movement, Ys> 75mm.

However, the site may be classified as P due to other factors such as low bearing strength, potential excessive foundation settlement, fill, mine subsidence, land-slip, collapse activity, coastal erosion, abnormal moisture changes or sites which cannot be classified otherwise.
The designer has to consider all the factors that may affect the foundation and design the structure accordingly.

SOIL TESTING SERVICES PROVIDED BY SNG ENGINEERS

New Homes
Extensions
Decks
Raise & Build Under
Retaining Walls
Swimming Pools
CBR Sampling