A quality control programme for performance evaluation of dynamic replacement of organic soil deposits

Abstract

Dynamic replacement (DR) is a relatively new ground-modification technique that has been used successfully to stabilize organic soil deposits by replacing the organic soil with sand columns. A full-scale DR field study was conducted in order to assess its effectiveness on Florida organic soils. A computer-based quality control system was developed using data-acquisition-management techniques to evaluate the degree of improvement of the organic soil layer at a given stage of treatment. One of the DR drop locations was instrumented in order to select technical criteria such as the print spacing and the number of blows per print for effective DR implementation, and to facilitate monitoring of the improvement of soil properties. The new quality control system evaluates the effects of treatment by computing the dynamic settlement modulus (DSM) from the impact acceleration data collected during the treatment period. This paper presents the results obtained from the pilot study and their subsequent use in establishing evaluation criteria for the test programme. It is also shown how the DSM-based treatment criteria are in agreement with those obtained from conventional methods. Hence, it is concluded that with the use of the quality control system presented, the implementation of any DR programme can be effectively monitored.