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Excavation Lesson 3 M. S. Martin Sept 2009 Slide 2 De - Watering The removal of ground water and / or accumulated rainwater from within excavations or earthworks by means of mechanical pumps. Usually to enable continuation of work. Slide 3 Typical Footings Slide 4 Slide 5 Slide 6 Slide 7 Slide 8 Slide 9 Shoring Slide 10 Shoring or Trench Support Manually or mechanically excavated trenches over 1.5m in depth require some form of support for the sides, to prevent possible collapse, while working in the trench. This is typically done by benching battering or shoring. Open or closed support systems are available in timber, steel or combinations of both. Slide 11 Shoring Add definition to P. 31 Trench support to sides of excavations to prevent possible collapse, typically trenches over 1.5m deep, must be benched, battered or shored. Slide 12 Timber Shoring Bracket head of screw jack Waler Waling hook Plate head Poling boards Wedges Waling Cleat Strut Bevelled ends OPEN TIMBERING OPEN METAL SHEETING Slide 13 Timber Shoring Slide 14 Slide 15 Report if you see any of the following Next two slides from J. Bridges (SWSI) slides on shoring & trenching Slide 16 Warning Signs If you notice any of the following situations, take remedial action and/or notify your supervisor immediately. Subsidence alongside trench Water entering trench Slide 17 Warning Signs - Contd Earth Fretting from sides Tension Cracks Deflection in Shoring Excessive creaking in shoring Slide 18 Surface & Sub-Surface Drainage: P. 20 It is a mandatory Local Council requirement to prevent surface eroded surface materials ending up in the street gutters and storm water pits/drains These fences may be constructed of Polypropylene (shade cloth) Straw bales Geotech fabrics, etc. Geotextile filter fabric 3000 max. Drainage area 0.6ha. max Slope gradient 1:2 max. Slope length 60m max. DISTURBED AREA UN-DISTURBED AREA Posts driven 0.6 into ground SEDIMENT FENCE 600mm 200mm Slide 19 Slide 20 Types of Drainage Surface Drains Dish Drains Rubble Drains Sub-surface drains Slide 21 Slide 22 Cut & Fill Sites P. 21 these types of sites need to have sufficient consideration to ensure adequate site drainage, and will typically use all of the drainage types mentioned above. Slide 23 Slabs Types: Slab on ground, basic garage, paths Raft Slab Waffle slab Stiffened Raft Any others ? Slide 24 Stiffened Raft Slide 25 Waffle Slab Slide 26 Slab Calcs Slide 27 Slide 28 Volume Slab Break the slab into two areas, i.e. the slab and the thickened splayed edge beam. Firstly, calculate the volume of the slab; L x W x T =7.5x3.8x0.1 =2.850m Slide 29 Volume Beam The simplest way of calculating the beam is to calculate the average area of the beam section and multiply it by the centre line length of the beam L x W 0.350 x 0.100 = 0.035m Now calculate the centre line length of the beam Slide 30 Beam Length Now multiply the average beam area by the average length to calculate the volume of the beam; Area x Length 0.035x21.200 0.742m Slide 31 Totals To calculate the total volume of concrete in the slab and the beam, add the two separate volumes together; Volume of slab + Volume of beam 2.850+0.742 = 3.592m ORDER - 3.6m of concrete