Introduction
The Vanstone Solid Manhole is a reinforced precast concrete inspection / service chamber or handhole suitable for underground telecoms services, more specific fibre optic installations. It is equipped with 8 knock out holes of 130 mm diameter, 4 unistruts vertically bolted on, a drainage sump, and a precast concrete lid that can be bolted down.
This type of manhole is available in a 'solid type' where the floor and walls are monolithic and a 'split type' with a loose floor. The last is for installers who prefer to lay the sleeves / pipes / cables first after which the manhole is placed over those services. For this purpose the end knock-outs are slotted down to floor level.
In order to facilitate the need for some variety in depth, two options are available: a 'Shallow' manhole (in solid and loose floors) and a wall extension for the loose floor type.
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Solid type: Walls and floor in one piece.
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Split type: Walls and floor in two pieces. |
For the Split type a wall extension may be added, which deepens the manhole by 350mm. The wall extension has the same knock-outs as the standard manhole walls. By using the standard walls on top of the wall extension, another eight knock-outs is effectively added higher up in the manhole. |
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Wall extension fits under the walls of the Split type, which in turn sits on the loose floor (not shown). Internal depth 1100mm. |
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Also in lockable steel lid (remote, programmable) for high security and full traffic loadings.
Refer : Dartcom (Pty) Ltd. |
click to enlarge |
Design
The Vanstone Solid Manhole has been designed in accordance with SABS 0100-1 2000 “The structural use of concrete” to safely withstand a static wheel load of 100kN. Although the lid is designed for the given loading and each lid is individually cast for each manhole to sit perfectly and eliminate rocking under traffic, concrete is a low ductility material and its durability under high volumes of heavy vehicle traffic is not proven nor guaranteed. For these situations special heavy traffic lids comprising steel as base material that is filled in with concrete should be used.
The tops of the walls are lined with 2 mm folded steel plate to protect the exposed edge against traffic.
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Design Criteria
- Limit state: Ultimate
- Imposed load: 100 kN static wheel loads acting vertically on lid.
- Load factor: 1.6
- Material safety factors: Steel 1.15; Concrete 1.5;
- Analysis: Static, simply supported.
- Concrete strength: 35 Mpa
- Reinforcing: High tensile steel main reinforcing to SABS 920
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During installation (courtesy Muvoni Weltex)
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