QUANTITY OF BOREHOLE LOG PER AREA
QUANTITY OF BOREHOLE LOG PER AREA
(OP)
Hi Engineers,
Can someone tell me the minimum distance between borehole logs or number per area, any standard reference?
Can someone tell me the minimum distance between borehole logs or number per area, any standard reference?





RE: QUANTITY OF BOREHOLE LOG PER AREA
B.3 examples of recommendations for the spacing and depth of investigations
(1) The following spacing of investigation points should be used as guidance:
− for high-rise and industrial structures, a grid pattern with points at 15 m to 40 m distance;
− for large-area structures, a grid pattern with points at not more than 60 m distance;
− for linear structures (roads, railways, channels, pipelines, dikes, tunnels, retaining walls), a
spacing of 20 m to 200 m;
− for special structures (e.g. bridges, stacks, machinery foundations), two to six investigation
points per foundation;
− for dams and weirs, 25 m to 75 m distance, along relevant sections.
(2) For the investigation depth za the following values should be used as guidance. (The reference
level for za is the lowest point of the foundation of the structure or structural element, or the
excavation base.) Where more than one alternative is specified for establishing za, the one which
yields the largest value should be applied.
NOTE For very large or highly complex projects, some of the investigation points generally extend to greater
depths than those specified under B.3 (5) to B.3 (13).
(3) Greater investigation depths should always be selected, where unfavourable geological
conditions, such as weak or compressible strata below strata of higher bearing capacity, are
presumed.
(4) Where structures under B.3 (5) to B.3 (8) and B.3 (13) are built on competent strata, the depth
of investigation can be reduced to za = 2 m, unless the geology is indistinct, in which case at least
one borehole should be taken down to a minimum of za = 5 m. If a bedrock formation is
encountered at the proposed base of the structure, this should be taken as the reference level for za.
Otherwise, za refers to the surface of the bedrock formation.
(5) For high-rise structures and civil engineering projects, the larger value of the following
conditions should be applied (see Figure B.1 a)):
− za ≥ 6 m;
− za ≥ 3,0bF.
where bF is the smaller side length of the foundation.
(6) For raft foundations and structures with several foundation elements whose effects in deeper
strata are superimposed on each other:
za ≥ 1,5⋅bB
where bB is the smaller side of the structure, (see Fig. B.1 b)).
RE: QUANTITY OF BOREHOLE LOG PER AREA
Dik
RE: QUANTITY OF BOREHOLE LOG PER AREA
The site is a Telecom site.
RE: QUANTITY OF BOREHOLE LOG PER AREA
Are you constructing a utility line? a building?
How long is the line? or what is the footprint of the building?...
How big is the site? Is it a flat site? Are there retaining walls? Are you cutting/filling for roads etc?
What geology are you expecting?
RE: QUANTITY OF BOREHOLE LOG PER AREA
RE: QUANTITY OF BOREHOLE LOG PER AREA
Dik
RE: QUANTITY OF BOREHOLE LOG PER AREA
EireChech, i will be constructing a mat foundation for a mast; size say 10x10m and the site is a flat terrain.
RE: QUANTITY OF BOREHOLE LOG PER AREA
RE: QUANTITY OF BOREHOLE LOG PER AREA
RE: QUANTITY OF BOREHOLE LOG PER AREA
RE: QUANTITY OF BOREHOLE LOG PER AREA
RE: QUANTITY OF BOREHOLE LOG PER AREA
If you are working an entire, "Site" you should have at least 3 borings.
The depth should extend throughout the seat of settlement, loosely taken as the depth where the improvements will not return more than a 10 percent stress increase to the original sigma V'.
For any pier footing that's more than 40 ft wide, we'd have at least 2 holes.
Any bridge founded on rock will extend at least 10 ft below rock with RQD >50 or such that we know we are below the anticipated depth to scour.
For retaining walls and sound walls, we'd drill (or require the designer) every 100 ft.
In terrain with acid-producing rocks, we'd drill more frequent core holes if the rock is dipping.
For cut slopes, we'd drill below the proposed toe elevation by at least the cut height (depth)?
There are too many site variables to have a cookbook for all eventualities. For example a site that needs ground improvement, we may need more frequent borings and deeper target depths.
We use CPT and DMT along with SPT.
Knowing the geology can prevent the need to drill to 100 ft just for site class. After 3 or 4 decades in one market, we sort of get that!
f-d
ípapß gordo ainÆt no madre flaca!
RE: QUANTITY OF BOREHOLE LOG PER AREA
cost of mobilization is much higher than adding a couple of bore holes..
RE: QUANTITY OF BOREHOLE LOG PER AREA