Method of consolidating foundation soils and/or building sites
There is described a method of consolidating foundation soils and/or building sites in general, which comprises injections of expanding chemical products which are projected and carried out by means of monitoring the effects which are progressively measured in the soil in the course of treatment by means of sequential tomographies of the electrical resistivity. Those consolidating injections will be carried out until the percentage variation of the electrical resistivity Δρ(%), measured in quasi-real time in the soil being treated and always with respect to the initial condition before the injection will not constitute sequential gradients (Nth) which differ from the preceding one (N−1) for variations contained in the range ±5%.
1. A method of consolidating foundation soils and/or building sites in general, including the steps of:
measuring the electrical resistivity in one or more volumes of the soil to be consolidated to determine the volume(s) of soil to be consolidated;
making one or more holes in the soil as far as or towards the volume(s) to be consolidated;
injecting an expanding resin into the hole(s) in the soil in order to perform a consolidation treatment;
geoelectric monitoring of the injections by progressive measurement of the percentage variations Δρ(%) of mean electrical resistivity of the volume(s) of soil to be consolidated between a state N of the treatment and the immediately preceding state N−1; and
interrupting the injections into a particular volume of the soil to be consolidated when the differences in the percentage variations of electrical resistivity
[
(
ρ
N
-
ρ
0
ρ
0
)
·
100
(
%
)
]
and
[
(
ρ
N
-
1
-
ρ
0
ρ
0
)
·
100
(
%
)
]
measured during the course of work in the soil, between the last state reached N and the immediately preceding state N−1, respectively, satisfy the following equation:
(
ρ
N
-
ρ
0
ρ
0
-
ρ
N
-
1
-
ρ
0
ρ
0
)
·
100
(
%
)
≤
5
%
.
2. The method according to claim 1 , wherein the step of measuring the resistivity precedes a step of treatment with mathematical algorithms to obtain a tomogram of the electrical resistivity of the soil to be consolidated.
3. The method according to claim 2 , wherein the tomogram of the electrical resistivity is three-dimensional.
4. The method according to claim 2 , further comprising a step of performing a penetrometric test prior to the injection step in order to define a local site correlation with the electrical resistivity tomogram.
5. The method according claim 1 , wherein a gradient of the variations in electrical resistivity is estimated during or after each individual injection or after a group of injections.
6. The method according to claim 1 , wherein the geoelectric monitoring step is performed by acquiring data by means of surface transmitter/receiver electrodes and/or depth transmitter/receiver electrodes in the soil, which electrodes are connected to a georesistivity meter.
7. The method according to claim 1 , wherein the expanding resin includes closed-cell expanded polyurethane.
8. The method according to claim 1 , wherein the injections of the Nth state may be performed either individually or simultaneously into one or more volumes of soil to be consolidated.
9. The method according to claim 1 , wherein the injections may be performed at a single depth level or at several levels, in a single solution or delayed solutions alternating with short intermediate pauses.
10. The method according to claim 1 , wherein the injections may be performed at superimposed levels, in a single solution or delayed solutions alternating with short intermediate pauses.