ABSTRACT:

Using different jet grouting methods and variable diameters, a series of samples have been taken by means of core drilling of jet grouting columns made in soft stratified soil. Average values of the compressive strength, tensile strength and secant modulus are presented as are the jet grouting process parameters and soil conditions. The influence of the water-cement ratio and the column diameter is discussed. Finally, four (exponential) expressions are presented interrelating the compressive strength and the tensile strength and the compressive strength and the secant modulus for jet grouted sand and jet grouted clay.

INTRODUCTION
General Information

The North/South metroline Amsterdam will use the shield tunnelling method for construction of two Æ 6,5 m metro tunnels. Therefore, due to settlements, complications with some historical buildings founded on pile foundations may occur. To prevent these complications, mitigating measures by means of stabilising the soil using injection-techniques, are planned at these locations. The lack of experience with injection in the vicinity of pile foundations, in combination with the fact that the non homogeneous, soft, stratified soil in Amsterdam has been injected to a limited degree, has led to the development of a "Full Scale Injection Test". Because of national interest, the Full Scale Injection Test is a co-operation of North/South Metroline Consulting engineers (75%), Centre for Underground Construction Studies (20%) and Delft University of Technology (5%). More information concerning the project can be found in other North/South metroline papers in ITA congress proceedings 1997, 1998 and 1999 (Van der Stoel, 1998 & 1999).

Process Parameters Jet Grouting

Jet grouting is an eroding process, and therefore both displacement as well as relaxation of the soil can occur during grouting. For the creation of the jet grouting columns, a one-and two phase jet grouting system combined with pre-cutting has been used.

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