SEA SELF DRILLING, THREADED, HOLLOW BAR / GROUT-ABLE SOIL NAILS / ANCHORS THE SEA SYSTEM SEA hollow T threaded bar Rock Anchors / Soil Nails provide the ultimate solution for securing unstable embankments and rocky slopes. The SEA system ensures a fast and efficient method of installation with superior strength and rigidity. The system is a comprehensive range of components designed to meet the most demanding challenges when reinforcing soils and rock by providing friction, shear and tension strengths to produce a monolithic earth structure. SEA's engineering expertise allows them to manufacture items specific to customer s requirements if required, this coupled with their research and development programme allows them to continually update and improve their products to meet the changing demands of the industry. RANGE OF DRILL BAR SIZES / STEEL TYPES SEA T Thread Bar hollow drill bar system includes standard bar diameters of 25mm, 32mm, 38mm and 51mm. The drill bars are available in a series of three strengths depending on the application, this provides additional flexibility for designers and contactors. Standard drill bar strength as follows; SEA 480 - is a mid-range product, manufactured from a high yield material. Suitable for most soil nailing applications, the material is also suitable for welding (welding recommendations advised by SEA) or the joining of sub-assemblies. SEA 680 - offers a superior yield soil nail product that is suitable for high strength applications in difficult or hard, rocky soil conditions. SEA Heavy Duty - Offering the highest yield In the range for applications requiring the greatest strength available in extreme conditions. The SEA production process crushes the thread on the bar which improves the grain structure and increases the yield but does not increase the material weight. The result is a Soil Nail which offers the highest Yield to Weight ratio. NB : SEA Rope Thread drill bar sizes 25mm, 32mm, 38mm, 51mm available but are not listed in this document. SEA T Thread Bar hollow drill bar can be supplied in either hot dip galvanised to DIN EN ISO 1461, raw steel or epoxy resin paint finish. SYSTEM MANUFACTURING STANDARDS SEA Rock Anchor /Soil Nail T thread bar hollow drill bar complies with Lloyds UKAS : ISO9001 standard and have ISO 9001 Accreditation, carry the CE Quality Mark and are independently tested by UKAS accredited test houses. SEA are Achilles Link-Up Accredited to supply the Rail Industry in the UK. Rev. Feb 2013 Sales orders / enquiries - Email sales@gtsl.co.nz - Phone 0800 436 832 - www.geotechsystems.co.nz Page 12 of 43
DRILL BITS SEA sacrificial drill bits compliment the T Thread Bar hollow drill bar to suit every ground condition from Hardened Star Cut Bit for loose ground and clays to Tungsten Thor Bit for hard rock and boulders. The sacrificial bit acts as an anchor at the bottom of the concrete core, providing additional strength to the application. DRILLING AND GROUTING SEA T Thread Bar hollow drill bar can be driven by a standard rotary percussive drill rig which injects grout down the hollow bar and out through ports in the drill bit creating a column of grout as the drill bit descends. By grouting as you drill, the grout penetrates into all loose material; filling cracks and fissures and therefore improving the bond with the surrounding soil. Unlike solid bar, pumping grout under pressure delivers a grout body of approximately twice that of a solid bar thus minimizing the likelihood of voids occurring. Dependant on ground conditions the increase in shaft diameter can be up to 2.5 times, this is due to the slow increase of pressure (up to 60 bar) as the grout is continuously pumped whilst rotating which reams the soil and causes the grout to penetrate further into the surrounding soil structure.this ream effect is caused partly by cured cement blocking the upward movement of grout and forcing the grout outwards from the rotating bar into the surrounding soil. ADVANTAGES OF THE SEA SOIL NAIL SYSTEM Quick to install as grouting can occur while drilling, soil nail installed in one operation. Hollow bar creates a column of grout as the drill bit descends resulting in increased bond strength with the soil. In softer soils pressure flushing of the hole while drilling removes the requirement for case lining of the hole Can be installed using smaller rigs which can cope with any slope angle and confined spaces. There is little vibration on installation, keeping disturbance to a minimum. Quicker installation rate with hollow bar, sacrificial bit and grouting immediately after drilling completed Do not 'jam' in the drive, making it easier to unscrew and add couplers and lengths. Range of yield strengths for all bar sizes A variety of drill bits for all ground conditions Increased hole / drive diameter results from flushing while drilling. TYPICAL APPLICATIONS Soil Nailed earth slopes and faces Rock face stabilisation Embankment retention / stabilisation Piling / Foundation Diaphragm wall / Cofferdam strengthening Underpinning Tunnel wall bolting / pining SEA SN SERIES T THREAD HOLLOW DRILL BAR DATA Product description Units 480 Series 680 Series Heavy Duty SN25 SN32 SN38 SN51 SN25 SN32 SN38 S N 5 l SN25 SN32 SN38 S N 5 1 Nom. outside dia. mm 25 32 38 51 25 32 38 51 25 32 38 51 Nom. inside dia. mm 17 24 27 38 17 24 27 38 15 22 25 35 Cross section average area mm 267 358 582 901 267 358 582 901 304 467 640 1036 Ultimate load kn 168 225 370 565 215 285 500 730 245 375 560 840 Yield KN 128 170 280 430 180 245 395 585 205 315 435 675 Ultimate tensile N/mm 630 630 640 630 810 800 875 810 810 800 875 810 Yield stress 0.2 N/mm 480 480 480 480 680 680 680 650 680 680 680 650 Weight kg/m 2.08 2.79 4 54 7.03 2.08 2.79 4.54 7.03 2.37 3.64 4.99 8.08 Thread : T type -- Left or Right Hand Left or Right Hand Left or Right Hand Lengths m 3 to 6 3 to 6 3 to 6 3 to 6 3 to 6 3 to 6 3 to 6 3 to 6 3 to 6 3 to 6 3 to 6 3 to 6 Visit SEA web site http://sea-construction.co.uk/soil-nails-installation-guidelines.asp Rev. Feb 2013 Sales orders / enquiries - Email sales@gtsl.co.nz - Phone 0800 436 832 - www.geotechsystems.co.nz Page 13 of 43
SEA SOIL NAIL COMPONENTS SEA DRILL BITS SEA TUNGSTEN THOR BIT FOR SOILS WITH HARD ROCK, RUBBLE & BOULDERS This robust drilling bit incorporates high grade tungsten. The positioning of the buttons optimize performance, breaking up and dispersing rock with minimum effort. 55 25 NA 75 32 90/25 100 38 110/32/25 SEA ROCK BREAKER BIT FOR SANDSTONE, CHALK & RUBBLE. Designed for use in medium drilling conditions. This drill bit features high grade tungsten cutting blades. 55 25 NA 75 32 90/25 100 38 110/32/25 SEA STAR CUT BIT FOR DRILLING IN SAND, CLAY & LOOSE SOFT GROUND This drill bit gives high performance and durability. This cross-cut type bit has hardened blades with the flushing hole situated behind the cutting edge for optimum grout delivery. 65 25 NA 90 32 90/25 110 38 110/32/25 SEA TRI-SPIRAL BIT FOR LAND FILL, MARL, MUDSTONE AND SHALE CLAYS. This multi-purpose drill bit has hardened spiral blades specifically designed to give better waste removal and superior grout mixing function. 65 25 NA 90 32 90/25 110 38 110/32/25 SEA MOLE BIT FOR SOFT GROUND CONDITIONS. This displacement bit can help prevent the expensive removal of waste material from projects such as highway developments, tunnels and toxic sites. The square design reduces skin friction to enable faster installation. 65 25 NA 90 32 90/25 110 38 110/32/25 T BAR THREAD PROFILE SEA-TECH ANCHOR PLATES SEA-TECH NUTS Anchor plates available in either galvanised or raw steel and come in a variety of dimensions, depending upon the application. Plates can be made to order, pressed or heavy duty for greater loads and have an articulation range of 0 degrees to 55 degrees SEA T THREAD BAR SPACERS Rev. Feb 2013 Sales orders / enquiries - Email sales@gtsl.co.nz - Phone 0800 436 832 - www.geotechsystems.co.nz Page 14 of 43
GENERAL PRINCIPALS FOR THE CALCULATION AND INSTALLATION OF SOIL NAILS DESIGN CONSIDERATIONS Soil Nails must penetrate into the passive zone by a minimum of 4 to 5 meters. Additional soil nails should be installed at the edge of the area being stabilized and the spacing of the soil nails, both horizontally and vertically must be directly related to the friction value of the soil. After excavation, soil nails should be installed as early as possible to ensure maximum strength is achieved. Delaying installation of the soil nails will allow the ground to relax which may further destabilize the area. Soil nails are installed typically in a grid pattern where there is a 'slip plane' on a slope between the Active Zone and the Passive Zone. The soil nail penetrates through the Slip and Active Zones and is anchored into the Passive Zone. No loads are applied to the soil nails until the ground moves which then activates the tension and shear values in the SEA soil nail. The grid pattern when activated creates a monolithic structure able to support the required loads Friction of the ground will determine the number of nails and their spacing. Length of Nails 0.5 to 0.7 x wall height but not less than 6.0m Capacity of nails Density of nails Amount of reinforcement Inclination of nails Deformation of nailed wall 50 to 250kN/m2 1.5 to 2 per m2 1.5 to 6.0 kg/m3 0 to 30 degrees 1.5% x wall height INSTALLATION SEA soil nails are installed using rotary percussive equipment and grout is simultaneously pumped down the inside of the hollow bar and out through 'ports' in the SEA drilling head. By grouting as you drill, the grout penetrates into all loose material filling cracks and fissures and therefore improving the bond of the soil nail with the surrounding ground. Depending on the ground conditions this system can use either 'air' or 'grout / water' as a flushing medium. Air is typically used where there is no danger of the hole collapsing, this is normally found in rock and hard ground. Under normal conditions a mixture of grout and water is pumped during installation and when the required depth is reached only pure grout is pumped. A weak grout / water cement ratio of up to 50kg of cement to 40 to 70 litres of water should be used at a pump flushing pressure of 5 to 20 bar. Care should be taken when installing in absorbent ground as the grout may tend to set very quickly, so it is advised to increase the water content on the primary installation and apply pure grout at the final stages ensuring pure grout returns to the surface. This will require a ratio of up to 100kg of cement to 40 to 70 litres of water. Close attention should be paid to the changing colour emerging from the installed anchor and only when the pure grout emerges should the pump cease The drill bits have radial flushing holes which will maintain the grout bulb at the drill head, this in turn maintains the column diameter throughout the full shaft length. If the ground has little or no clays or peats and is predominantly rock, then flushing can be done with air, water or a weak grout / water mix. The positions of the flushing holes in the SEA bits allows for a degree of pressure or 'crowd' to be applied whilst drilling to increase installation speeds. Care needs to be taken to ensure the visible flush at the surface doesn't stop which would indicate excessive 'crowd'. Too little 'crowd' and the water or grout mix will overflow. Correct flushing flow as pictured opposite. NOTES 1. Normally the Star Cut bit is the first choice if there are no hard rock bands. A very cost effective bit giving high installation rates. This bit cuts with a shear action to slice and mix the material being cut. Unlike other bits, the flushing holes are positioned behind the cutting blade to move material quickly away from the drill head. The hardened blades enable the bit to cut through tough Clays, Sand and weak Rock bands. 2. As a general rule approximately 2 bar pressure is required to lift one meter of grout. An advantage of using a percussion hammer for installation is the oscillation action acts like a vibrator during the drilling and final grouting process and the consequent results is a homogeneous and compacted grout body. Rev. Feb 2013 Sales orders / enquiries - Email sales@gtsl.co.nz - Phone 0800 436 832 - www.geotechsystems.co.nz Page 15 of 43
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