BS/EN 12716-2018 pdf download.Execution of special geotechnical work-Jet grouting.
7.1.5 Site conditions which may influence the working sequence of the elements shall be specified.
7.1.6 When relevant, the detailed execution sequence should be shown on the printed or electronic execution drawings and/or models.
7.1.7 Where no comparable previous experience is available representative preliminary field tests shall be carried out, using the equipment, materials and techniques proposed for the main jet grouting works.
7.1.8 To ensure a consistent result in the preliminary in situ test, at least one jet grouted element should be constructed with a given working procedure. In significantly heterogeneous ground conditions more test elements and different working procedures should be necessary for approval.
7.1.9 Where the eL grouted material is to be subjected to aggressive or temperature sensitive environment, the preliminary in situ tests should be preceded by specified laboratory tests on samples of the soil to be treated and the grout, mixed in proportions encompassing the working range envisaged.
7.1.10 The determination of the characteristic material strength as part of the supervision, testing and monitoring shall be made by testing of samples, preferably of sample quality class A and B according to Annex B, taken from the jet grouting body itself either by core drilling, fresh sampling or from spoil return.
NOTE The reference geometry of samples for this purpose Is a cylinder with a ratio of height versus diameter of 2.
The diameter of the sample should correlate to the largest grain size contained (see Annex B).
Spoil return samples should only be used, if they can be expected to be representative for the material strength based on previous experience.
7.1.11 Structural elements shall be loaded only after testing or comparable experience has confirmed that the curing time is sufficient to achieve the required strength specified by the design.
7.1.12 The characteristic strength determined as the uniaxial compressive strength for jet grouting elements as part of supervision, testing and monitoring shall be verified statistically in accordance with the specifications, e.g. as described in Annex A.
7.1.13 For the determination of the characteristic strength the minimum number of samples is set out in Annex C.
7.1.14 Samples should be taken where a representative material strength can be expected.
a) plan location of vertical and raking jet growing elements referenced to the working platform level ≤ 0,10 m;
h) deviation from the element’s axis
1) for vertical jet grouting elements 2 % of the maximum drilling length,
2) for sub-vertical jet grouting elements ≤ 4% of the maximum drilling length,
3) for inclined and sub-horizontal jet grouting elements ≤ 6 % of the maximum drilling length.
7.2.3 The following shall be clearly shown on design drawings:
— minimum cross sectional dimensions of jet grouted elements to be achieved in the different soil layers that will be encountered;
— tolerances on the position and inclination of the element axes if different from 7.2.2.
7.2.4 Maximum cross sectional dimensions should also be considered and related to the element spacing to ensure the integrity of a jet grouted structure.
7.2.5 If any unexpected underground obstruction cannot be removed, the relevant area shall be marked on the printed or electronic design drawings and/or models, and the adjacent jet growing treatment shall be redesigned so as to achieve the intended purpose.
7.3 Strength and Deformation Characteristics
7.3.1 The strength of a jet grouted material depends on the jet grouting system selected, the parameters employed and on the soil type and its heterogeneity.
7.3.2 In underpinning applications stability and deformation in the temporary condition, prior to set, of the jet grouted columns beneath foundations shall be taken into account.
7.3.3 Where deformations of jet grouted elements or of jet grouted structures are an important concern, the design shall state the parameters and deformations to be measured in specified acceptance tests and during execution.
7.3.4 The required characteristic strength of the jet grouted material shall be established at the design stage, taking into consideration the variability of the soil properties. Verification of the characteristic strength shall be performed, e.g. according to Annex A.BS/EN 12716-2018 pdf download.
BS/EN 12716-2018 pdf download
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