Evaluation of pre-grouting for the city line project using the RTGC method

• An access tunnel for the City Line project in Stockholm was excavated in the early parts of 2010. The works also included pre-grouting with cement. The performance of pre-grouting operation was evaluated for 14 continuous fans that included 326 grouted holes. A method called “Real Time Grouting Control (RTGC)”was used in the analysis. It is shown how the RTGC method can be used to investigate the effectiveness of existing stop criteria. It is first time an evaluation using RTGC carried out in this magnitude. The water inflow to the tunnel after grouting satisfied requirements. The grouting effect is quantified by assessments of the average conductivity of the rock mass and of the grout spread outside the tunnel. The evaluation indicates that the stop criteria in the design were chosen conservatively relative to the achieved grouting results. A model is discussed where the required grout spread is used as a design parameter to quantify the potential for reducing the pumping time.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Samhällsbyggnadsteknik -- Geoteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Civil Engineering -- Geotechnical Engineering (hsv//eng)

Nyckelord

Dimensionality

Grout spread

Pre-grouting

Real time grouting control method

Stop criteria

Concrete construction

Mortar

Control methods

Design parameters

Grouting effects

Grouting result

Pumping time

Water inflows

Grouting

Publikations- och innehållstyp

ref (ämneskategori)

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