We already know how to check the quality of gravel pillars

The soil on which construction work is to be carried out does not always have sufficiently good mechanical and physical properties. One of the commonly used methods for improving the quality of the soil body is gravel pillars. But how to ensure the quality of the gravel pillars implemented when there is no uniform system for their verification? Scientists from the Faculty of Civil Engineering have found the answer to this question.

At present, the quality of completed gravel piers is based only on a basis of trust between the contractor and the construction supervisor and on a non-uniform system of inspection tests, the types, numbers and interpretation of which can be a topic of discussion leading to numerous disputes.

Figure 1: Implementation of gravel pillars (source: kellergrundbau.cz)

A team of scientists from the Institute of Geotechnical Engineering, Faculty of Civil Engineering, Brno University of Technology, together with GEOSTAR, focused their research on the problem of unclear rules and criteria for the inspection of gravel pillars. The result of their work is a test field for the verification of the quality of gravel pillars. This makes it possible to standardise test procedures and use the results obtained as a model for quality control of other gravel pillars

The design of the test field, which has been registered as a utility model under the title Test field for quality verification of gravel pillars, describes the exact arrangement and number of pillars for a given type of grid design (rectangular or triangular), the procedure for their manufacture and also strictly specifies on which pillars what test will be carried out (dynamic penetration test, penetration test, static load test with a circular plate, etc.).

Figure 2 shows an example of one type of test field design. It is an interlocking square arrangement of 15 pillars that are subjected to various tests (see legend).