EN 14490-2010 pdf download.Execution of special geotechnical works – Soil nailing.
8.4.4.1.6 Grout mixing should be camed Out in a mixer capable of producing a grout of uniform consistency with the workability and strength characteristics required by the design. Grout should be used immediately after mixing, unless a facility is available to agitate the mix.
8.4.4.1.7 Weight or volume batching of constituents may be used.
8.4.4.2 Gravity grouting
8.4.4.2.1 When grouting an open hole via a grout tube, the grout pressure in the borehole cannot exceed gravity pressure.
8.4.4.2.2 Gravity grouting should be performed. using a grout tube of internal diameter not less than
15 mm. which is advanced to the base of the borehole, prior to grouting commencing.
8.4.4.3 Pressure grouting
8.4.4.3.1 Pressure grouting can enhance the pullout capacity of a soil nail. The most effective procedure for pressure grouting is normally established by means of trials (grout pressure and injection volumes).
8.4.4.3.2 Pressure grouting of driven nails can be performed by connecting a grout pipe to the head of the reinforcing element and injecting grout on completion of driving.
8.4.4.3.3 On completion of gravity grouting through a drill casing, or auger stem, a grout pipe may be coupled to the casing or auger head and a pressure exerted on the grout within the borehole during casing/auger withdrawal.
8.4.4.3.4 For self-drilled hollow bars, the grout-flushing medium, which is commonly a cement grout, is introduced into the reinforcing element via a grout swivel fitted into the drilling rig. The grout injection pressure and flow rate should be adjusted during drilling depending on the grout’s susceptibility to penetrate the ground. loosened by the drilling process and contained within the annulus around the reinforcing element. Grout flushing should be carried out at a constant rate, and the flush should be re-established each time new sections of the reinforcing element are added, prior to advancing the drill bit.
8.4.4.3.5 Some types or drilled and grouted nails allow the installation of a post-grouting pipe, which may allow single-stage grouting or high-pressure multi-stage post grouting of the soil nail to enhance pullout capacity.
8.4.5 Other nail Installation methods
8.4.5.1 If using another soil nailing technique. it shall be installed in accordance with the design specifications.
8.4.5.2 Specific tests with definite performance criteria shall be conducted in order to verify that the method will achieve the performance requirements specified by the design.
8.5.1.1 The effective control of surface and groundwater is essential during construction and service life of a soil nail construction. Drainage measures shall therefore be constructed to a high standard to protect the soil nail works from the detrimental effects of surface water and groundwater, both during construction and the design life.
8.5.1.2 If groundwater or surface water flows are greater than anticipated, then the design shall be reviewed.
8.5.1.3 The effects of surface water can be controlled by a variety of measures, such as cut-off trenches. channels. bunds. sumps and sheeting. Measures to control surface water should generally be Installed prior to commencing excavation or the stripping of vegetation.
8.5.1.4 The effects of groundwater can be controlled by internal drainage measures, such as upwardly inclined well screen drains and trenched drains, or by the construction of a drainage blanket immediately behind the facing, often in combination with weep holes.
NOTE Pockets of water or perched water tables known to exist, or revealed during soil nail execution, are normally controlled through the deep drain system.
8.5.1.5 Where adverse hydraulic conditions are encountered, then measures required for controlling water during soil nail construction and preventing erosion of excavated faces shall be implemented and agreed before further excavation.
8.5.1.6 Surface water and groundwater from drains should be channelled to collection points, where It can be discharged safely and in accordance with environmental regulations.
8.5.2 Surface drainage
8.5.2.1 If surface drains are employed, they shall have sufficient capacity to collect and control rainwater flows arising from the storm with a return period equivalent to the design life of the works.
8.5.2.2 If sheeting is employed to collect surface water, attention should be paid to the jointing and overlapping of sheets to prevent water entering between the sheeting and ground. Where necessary, it should be pinned or weighted to keep it in intimate contact with the ground surface and prevent it from lifting under wind loading. Sheeting should be inspected regulariy for damage and repaired as necessary to maintain serviceability.
8.5.2.3 If drainage channels are constructed, they should have a continuous fall to a collection point and shall prevent ponding of water. If collecting surface water from a slope, they should be detailed to ensure the water runs into the channel and does not pass into the ground below the channel, Where constructed directly on the ground surface, the ground should be well compacted. Construction joints should be watertight to prevent ingress of water and erosion of the soil below the channel. Details should be included to prevent damage to the channel due to differential or thermal movement.EN 14490-2010 pdf download.
EN 14490-2010 pdf download
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