BS EN 12716:2018 pdf download.Execution of special geotechnical work – Jet grouting.
5 Geotechnical investigation 5.1 General 5.1.1 The general requirements for site investigation are contained in EN 1997-2 and the relevant national documents. 5.1.2 The depth and the extent of the geotechnical investigation should be sufficient to identify all ground formations and layers affected by the jet grouting works, to determine the relevant properties of the ground and to determine the ground conditions. 5.1.3 Relevant experience of the execution of comparable jet grouting works under similar conditions and/or in the vicinity of the site should be taken into account when determining the extent of site investigation. 5.1.4 The ground investigation report shall be available, to allow for reliable design and execution of the jet grouting works. 5.1.5 The sufficiency of the geotechnical investigation for the design and execution of the jet grouting works shall be verified. 5.1.6 If the geotechnical investigations are not sufficient, a supplementary investigation shall be conducted.
5.2 Specific Requirements 5.2.1 Particular attention shall be paid to the following aspects, which are relevant to the execution of jet grouting: — the ground level at any point of investigation or testing relative to the recognized national datum or to a fixed reference chart datum; — piezometric levels of all water-tables and permeability of the soils; — presence of coarse, highly permeable soils or cavities (natural or artificial), which can cause sudden losses of grout and instability of the borehole during jetting or which can cause a sudden drop of fluid level and thus can require special measures; — presence, strength and deformation characteristics of cohesive soils, such as clay or peat, which can cause difficulties during jetting; — presence of boulders or obstructions which can cause shadows during jetting and, an assessment of their size and frequency, when applicable; — presence, position, strength of hard rock or other hard materials which can cause difficulties during drilling and may require the use of special tools; — presence, extent and thickness of any strata that can be sensitive to water infiltration or additional hydrostatic pressure caused by jetting; — strata where high ground-water velocities exist that could wash out the fresh jet grouted material; — detrimental chemistry of groundwater, soil and rock, and water temperatures if required;— presence of pre-treated soil, which can have an adverse effect during jetting; — mining beneath the site; — site stability problems (slope stability for instance). 5.2.2 The piezometric levels of the various water-tables existing on the site shall be monitored separately and over a sufficient period of time to estimate the highest piezometric levels which can occur during jet grouting. 5.2.3 Particular attention shall be paid to artesian conditions. 5.2.4 The relevant properties of the soils shall be determined by laboratory tests and/or in situ tests over the full depth of the jet grouting elements and to a certain depth below their base. 5.2.5 When jet grouting elements are required to connect to the rock, the level of the rock surface shall be determined and where relevant its properties including its strength, the degree of weathering and the extent and direction of fissuring.BS EN 12716 pdf download.