Velatia ORMAZABAL basic pfu Series - Preparing the Ground; Excavation Drawings

IG-032-EN version 05; 18/06/2019
21
General instructions
pfu basic range: Prefabricated concrete
enclosure, ground-level walk-in type
Installation
8.4. Preparing the ground
8.4.1. Excavation drawings
The excavation levels indicated below must be respected.
The ground must support the weight of the pfu model,
including the switchgear tted in each case. The pressure
exerted on the ground by the pfu never exceeds 1 kg/cm
2
.
If ground bearing capacity is insucient, it may give way
or cause loss of levelling, producing dierential settlement.
Such settlement may damage the pfu structure.
There are two types of ground:
1. Ground with hardness greater than 1 kg/cm
2
:: spread
a 100 mm layer of sand over the ground and compact it
properly. Take the measures appropriate to each case to
prevent the lling sand from eroding.
2. Ground with hardness less than 1 kg/cm
2
: the base
of the pit must be covered with a layer of reinforced
concrete of at least 100 mm thick, on which a 30 to
50 mm thick layer of sand must be laid, using a level
board.
*Check with Ormazabal to dene the thickness of the concrete slab.
1
Concrete slab (required if soil bearing capacity
is less than 1 kg/cm
2
)
2
Levelling sand layer
a
Excavation length
b
Excavation depth
c
Sand layer thickness
Figure 8.2. Excavation dimensions for pfu (in mm)
pfu-3 pfu-4 pfu-5 pfu-7
Length (A)
4080 5260 6880 8880
Excavation depth (b)
Soil bearing capacity > 1 kg/cm
2
≈ 560
Soil bearing capacity < 1 kg/cm
2
≈ 600
Sand layer thickness (c)
Soil bearing capacity > 1 kg/cm
2
100
Soil bearing capacity < 1 kg/cm
2
30 – 50
Table 8.2. Excavation dimensions (en mm)
When installing on a slope, please ask Ormazabal.