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https://nap.nationalacademies.org/catalog/27432/critical-issues-in-transportation-for-2024-and-beyond

DEVELOPMENT OF QUALITY CONTROL METHODS FOR DEEP STABILISATION

SYVASTABILOINNIN LAADUNVALVONTAMENETELMIEN KEHITTAMINEN

A research project focusing on developing quality control methods for deep stabilisation, STALAMIT, began in spring 2002. The project is part of the PRIMA development programme. The research aims at developing a dynamic compaction control method to provide a suitable quality control method for deep stabilisation. The aim of using the method was to try to reduce the uncertainties related to deep stabilisation quality control. Deep stabilisation has suffered from problems with both local and column-specific homogeneity. The development of the quality control method is aimed at studying the local success of deep stabilisation, in particular. On the basis of local data, it could then be possible to direct column-specific studies, such as rotary boring, to less strengthened areas. The dynamic compaction control method was developed for monitoring the compacting of road and field structures. In the method, accelerometers, measuring the response from the layers being compacted, are installed in the axle of a smooth roller. International studies have shown that gravel columns strengthening railway embankments could be observed in the response measurements of dynamic compaction control as definite peaks in compaction. This led to the idea of developing a version of the method that would be suitable for deep stabilisation quality control. The research is a public target study funded by the National Technology Agency Tekes, the cities of Helsinki, Espoo and Turku, Helsinki Water, Partek Nordkalk Oyj and Rakennus Oy Lemminkaeinen. The rolling equipment used in the test rolling was supplied by Rotator Oy. The one-year study ended in spring 2003. The project was divided into the following subtasks: a preliminary study of the dynamic compaction control method, drawing up the plans for the test sites and instrumenting the test compaction sites, monitoring, and processing and analysing the measurement results. The suitability of the dynamic compaction control method was tested at three test sites: Kivikko in Helsinki, Perennakatu Street in Turku and a test embankment in Tolsa in Kirkkonummi. Of the test sites, deep stabilisation was carried out as column stabilisation in Tolsa and Perennakatu. At the Kivikko site, both mass stabilisation and column stabilisation were used. A crushed rock layer approximately half a metre thick was constructed on top of the strengthened columns or the mass stabilisation to provide a driving surface for the roller. In addition to the roller's own accelerometers, VTT's accelerometers were installed on the rolling equipment used in the tests. The test roller was driven over the crushed rock layer several times over the same spot. The length of the roller's eccentric stroke was varied on different passes, thus changing the impact of the rolling. The aim of the measurements on the column stabilised area was to look for columns in the rolling response (peaks in the response) and compare them with each other. On the mass stabilised areas, the aim was to look for deviations in the measurements, that is, less strengthened areas. The analysis of the results show that no columns can be observed at the Kirkkonummi site. Although peaks were observed in the results, they do not seem to coincide with the columns. This naturally also means that the quality of the columns cannot be estimated from the results. The great size and weight of the roller used, as well as the position of the measuring instruments in the roller's axle, meant that the sought-for measuring response was too small in relation to the mobilised forces to be reliably discernible from other noise in the measurements. The results from the Turku site were analysed differently, for instance by using Fourier transformations. The rows of columns were observed on the basis of these results, but no conclusions could be drawn as regards the strength of individual columns. There were local strength variations in the results at both the Kirkkonummi and Turku sites. On the basis of these, it is possible to direct column surveys to the less strengthened areas. At the combined mass and column-stabilised site in Kivikko, it became evident that the columns cannot be detected from under the mass stabilisation.

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  • Corporate Authors:

    TIEHALLINTO, FINNISH ROAD ADMINISTRATION

    OPASTINSILTA 12 A
    HELSINKI,   Finland  FIN-00520
  • Authors:
    • Korkiala-Tanttu, L
    • TORNQVIST, J
  • Publication Date: 2003

Language

  • Finnish

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Filing Info

  • Accession Number: 00970149
  • Record Type: Publication
  • Source Agency: VTT Technical Research Centre of Finland
  • ISBN: 951-803-062-6
  • Files: ITRD
  • Created Date: Mar 5 2004 12:00AM