FR2524145A1 - METHOD AND APPARATUS FOR CONTROLLING THE INJECTION AREA OF A SOIL CEMENTING AGENT DURING A SOIL STABILIZATION PROCESS - Google Patents

Abstract

The invention relates to a method and an apparatus for controlling the area of injection of a cementing agent into a soil. THIS PROCESS FOR MONITORING A ZONE 21 OF A SOIL INTO WHICH A CEMENT AGENT IS INJECTED CONSISTS OF PROVIDING THE ELECTRODES 27, 28, 29; 27, 28, 29 IN THE SAID ZONE, TO SEND A CURRENT TO THE ELECTRODES FROM AN ENERGY SUPPLY SOURCE 31 AND TO MEASURE IN 32 THE VARIATION OF THE ELECTRICAL RESISTANCE BETWEEN THE ELECTRODES, THE CEMENT AGENT BEING INTRODUCED BY HOLLOW RODS 24, 24 CARRYING THE ELECTRODES. APPLICATION IN PARTICULAR TO THE CONTROL OF THE RESISTANCE OF A SOIL DURING ITS STABILIZATION.

Description

The present invention relates to a method and apparatus for controlling

an area or region of a soil,

  in which a cementing agent, for example a

  chemical product (hereinafter simply referred to as a chemical) is injected during a process

soil stabilization.

  Recently, a certain type of statistical procedure

  The process is such that a solidifying chemical is injected into the desired part of a soil in order to solidify and solidify and stabilize the soil. this makes the soil or

to make it waterproof.

  Soil types requiring stabilization include ordinary soil layers, cracks in rocks, broken and dislocated areas or any combinations of these, and

  cementing depends, in many cases, on

  properties of the layers or strata of the soil.

  In other words, when the chemical product

  injected stabilization leaves the cement tube

  tion, it enters the layers or strata

  applied pressure and tends to penetrate di-

  or within the area of the strata presented

  both the minimum resistance to cementation, for example

  at the level of the boundaries of the soil layers or the cou-

  gravel or soft clay

  a high coefficient of permeability.

  This is why there is the risk of

  phenomenon that the entire injected chemical is not necessarily solidified within the intended area of the soil

  if the gelling time of the chemical is

Glee.

  When implementing this type of operation,

  t.Lon of bringing the chemical, it is necessary

  to observe the existence of a leak of the chemical product

  in order to prevent the latter from escaping

  the outside of a predetermined zone for bringing the

  a chemical sink around the cementing hole for the injection of the chemical and entering wells, a pond or the like in the vicinity of the work site, which would result in pollution of the water table or water located in the basin More specifically, this observation is carried out by drilling and placing wells

  on the outer side of a breathing zone.

  from the chemical having a radius of about 1 m from the center of the cementing hole for the injection of the chemical,

  control of water quality in the observation wells

  at three different times, ie before, during and after injection of the chemical into the cementing hole, comparing the control data obtained and confirming the leakage of the product

  outside the predetermined area of ame-

  or injection of the said chemical product.

  However, when implementing such an observation method, if there is a case where the value of the p H of the water in the observation well

  exceeds a predetermined reference value, by following

  the effective escape of the chemical to the outside of the chemical feed zone, based on the test performed at the time of injection,

  which is one of the three steps of the test of

  the quality of the water, it is necessary to immediately stop the operation of bringing the chemical at the location where the cementing hole

  used for the injection of the chemical is located.

  In reality the control of the quality of water in the

  observation well during injection of the chemical product

  a significant time interval until the chemical escaping outside the delivery zone is infiltrated into the water inside the observation well, due to the dis-

  about 10 m between the cement hole

  tion and the observation well. As a result, since

  given that the operation of bringing the chemical product

  gresse considerably before it is discovered that the value of the p H of the water at the location of the observation well exceeds the reference value, the supply operation must be stopped at that moment and it is necessary to drill a cementing hole again at a different location, and the operation must be re-triggered from the initial phase, resulting in a considerable loss of the point of view.

  time, equipment and manpower.

  In order to overcome these disadvantages, methods have recently been proposed whereby

  As an example, we first introduce a

  instant chemical solidification in order to guarantee

  to obtain a stabilized area of the soil, then

  the usual operation of bringing the

  chemical product, and in general it is difficult to

  to hold, by means of such a method, a confirmation

quantitative of the cemented zone.

  To determine the solidified zone, it was

  proposed different methods including in the main

  eg the creation of an excavation in the ground as well as

  the implementation of permeation coefficient measurements.

  a penetration test, measurement using a radioisotope, measuring the specific resistance of the ground, the seismic method, etc. Although performing an excavation in the ground, the use of a radioisotope or the seismic method were methods used in the case of

  large-scale soil stabilization work, the use of

  The use of these methods is not universal.

  given that the results of the measurements were not justified

  In a satisfactory manner, the measurement method using the specific soil resistance has not been used frequently and has instead been used for

  prospecting for water veins in the soil and the like.

  In these circumstances, although the process of determining

  nation the screen effect or blocking based on the

  the coefficient of permeability has been extremely

  used, this process has not always been uniform

  versel and was not developed to a state making it

suitable for its use.

  In view of these conditions, he was

  common practice, in the context of

  of the prior art of soil stabilization used

  injection of chemicals,

  kill the job when injecting a quantity

  of a chemical without or without

  sibility to confirm the actual condition reached once

  completed the stabilization work.

  The present invention aims to solve

  the above drawbacks of the prior art and is based on the discovery that, as a result of various researches on electrical resistance measurements, which have not

  been used extensively in view of the circumstances

  previously mentioned, it has been found that

  their measurements show a quantitative behavior and accused in relation to the electrical resistance,

  in the case of the presence of a gel in the soil.

  This is why the main purpose of the pre-

  It is an object of the present invention to provide a method of controlling

  the injection zone of a cementing agent into the soil for controlling an injection zone of a cementing chemical during a soil stabilization process, which consists of disposing of electrodes in an area to be monitored, to record a current produced by a

  source of energy and to measure the variation of a

  electrical resistance between the electrodes, and

  a process for controlling the work performed and a measuring apparatus implementing said method of

control.

  Other features and benefits of

  the present invention will emerge from the description

  given below, taken with reference to the

  in which: FIG. 1 is a sectional view of a support

  or pivot to three tubes of cinentation for the injection

a chemical product;

  FIG. 2 is a schematic diagram

  to clarify the state in which a chemical product

  that is injected into a hole drilled by means of drills; Figure 3 shows the state in which a gel

  test is buried in sand, Figure 3 (a) shows

  with a plan view and Figure 3 (b) a cross-section view.

  axial transverse pe; Figures 4 to 6 show graphs

  showing curves of variation of electrical resistance

  between electrodes as a function of their distance in the ground;

  FIG. 7 is a schematic diagram of

  the positions of a cementation tube used to

  the injection of a chemical product and obersa-

tion:

  FIG. 8 is a schematic diagram of

  the way in which a chemical is injected according to a high-pressure injection process;

  FIG. 9 is a schematic diagram of

  the state in which a chemical is injected

  by means of a drilling tube of the cir-

  before injecting a chemical product; and FIG. 10 is a graph illustrating the

  cementing operation performed.

  In accordance with the present invention, the

  my "chemical" means any of the

  chemicals that are commonly used in soil stabilization, including for example organic chemicals, such as lignin and urea, acrylic acid and acrylamide chemicals, and water glass, milk cement, etc. The term "area to be measured" refers to an area ideally covering a region or

  uniform radius space from a cement tube

  introduced into the soil and into which the chemical injected into the pipe is required to penetrate, or an area

  non-uniform permeability in the soil, if such

  ficients have already been determined by drill holes

  The term "electrode" refers to an electrode which produces and receives a measurement current and which, if placed in a cementation tube for

  the injection of a chemical product, should be

  separating the cementing tube with an insulator, such as a plastic, and being protected by a boltier having a reliable resistance With regard to the arrangement of the electrodes in the tube

  cementing agent for the injection of the chi-

  If a single electrode is used, this last

  is buried near the end of the cementation tube, for example at a part of the

  When installing multiple electrodes, they are

  in the wall of the cementation tube at intervals

  appropriate and used as is.

  When such electrodes are arranged on an observation tube, it would be preferable to provide as many electrodes as possible so as to make a multiple observation with a

high degree of accuracy.

  Each of the electrodes arranged on the tube

  cementing agent for the introduction of the

  and on the observation tubes is connected to the wires

  conductors inside the tube and is connected to

  then to a transmitter and receiver placed on the ground. A specific example of an apparatus for carrying out the method of controlling a region of injection of a chemical used for cementing comprises a support or pivot having a

  closed electrical circuit between at least one door

  placed on the head of the pivot and a cable connector

  disposed in the central part of the lower end

  the pivot, through a sliding brush

  and a cable, a rod of the cementing tube

  a cable conduit having a cable connector at each end and disposed at the center of a tube having a plurality of concentric tubular elements, and a cementation tube rod equipped with an electrode and containing a conduit for a cable having a connector for a cable at each end and disposed at the center of a tube with concentric multiple tubular elements, and an electrode disposed on the outer wall of the tube and connected to a conductive wire extending from

  cable duct, with the pivot and the rods being

  nected between them appropriately.

  We will now write in more detail

  With reference to the accompanying drawings, the construction

  of the apparatus with a cementation tube for injecting

of a chemical product.

  By way of example, FIG. 1 represents a pivot or support with three tubes, which comprises several terminals 1 arranged on the head of the pivot and which are each isolated from the environment by means of

  an insulator 18 Each terminal l is connected by the in-

  of a sliding broom 4 to a rotating terminal

  ve 3 mounted on the outer side of an electric spindle

  trode 2, which is sealed to the

  of the tube portion of the pivot so as to rotate about its axis and, likewise, conductors son are also out of the interior of the terminals

  3 and are connected to a connection terminal

  appropriate, for example a cable connector

  6 mounted on the lower end of the pivot, by the

  a cable duct 5 disposed at the center of

be the body of the pivot.

  There is provided a medial tubular element 7 serving to finally form a first passage 9 for the fluid between itself and a tubular sheath 8 of the pivot, and its upper part forms a closed passage

  above an inlet 10 for a fluid.

  A coaxial inner tubular element

  is disposed within the tubular element

  dian 7 so as to form a second passage 12 for the fluid between itself and the median tubular element

  7, and its upper part forms a closed passage

  above a second inlet 13 for a fluid.

  The medial tubular element 7 and the tuft element

  Inner bungee 11 are worn with possibility of

  rotation, in a sealed manner, by tori joints

  14, ball bearings 15, U-shaped cups

  16 and an oil seal 17.

  The end of the tubular sheath 9 of the pivot,

  of the medial tubular element 7 and the tubular element

  interior 11 is carried out respectively under the

  plug or socket for the connection

  to a cement tube stem (a triple tube

  in the present embodiment).

  The end connection part of the cable

  ble, including the cable connector 6, etc., may have some tolerance over the length of

  to facilitate the coupling operation of the con-

  cable connector during the connection operation

of the stem of the cementation tube.

  Naturally, the stem of the cementation tube has a cable with a cable connector at each end and has a three-tube constitution that provides first and second passages

  for the fluid in correspondence with the pivot.

  If the pivot and stem of the cementation tube described above is used, it is possible

  example of connecting an external power source

  energy consumption at terminals 1 arranged on the head

  of the pivot so that the application of a voltage

  property (for example, about 6 to 12 V) causes the

  passage of a current in the ground from the elec-

  trode the cementation tube, along the cable ducts It follows that, if available separately

  the electrodes so as to capture the current in different

  In many places, it is possible to easily determine the supply condition of the chemical.

  according to the rate of decrease of the resistance

  electrical power varies according to the extent (or the layer thickness) of the injection zone

chemical.

  We will continue to describe another form of

  realization of the apparatus, in the form of a

  soil forming cement piles of solidification, shown in Figure 2 Drills 23 and 23 'of the double type are inserted in a determined soil 21 so as to allow the injection of a cement milk 26 from the ends or fins 25 and 25 'of the drill rods 24 and 24' while spraying the soil particles, and the cement milk 26 and the particles

  22 of the soil are agitated and mixed together.

  24 and 24 'of the drills are respectively equipped

  electrodes 27, 28, 29 and 27 ', 28', 29 ', which are

  placed at identical intervals and are insulated from the associated rods themselves, and a conductive wire 30 or 30 'extends from each electrode inside the rod 24 or 24', up to the inside

  The conductor wires 30 and 30 'from the electrodes

  trodes are connected in such a way that a source

  energy supply 31 and a strain gauge

  32 are arranged between the electrodes 27 and 27 ', 28 and 28' and 29 and 29 ', which are installed in the same vertical positions on the rods 24 and 24' of the

drills.

  Before setting up a fresh concrete

  mixed A in the vicinity of the soil particles de-

  provided by drills 23 and 23 ', and cement milk

  24 sent through these forests, we would like to

  Preliminarily pare on the ground a sample

  under the same conditions or under similar conditions

  to those of freshly mixed A concrete, and to

  using this sample, we obtain the necessary data.

  on the values of electrical resistance in freshly mixed concrete

  that one wishes to obtain This data of exchange

  for example by adding and mixing a mixture of predetermined amounts of cement and water to the particles of the sprayed soil

  22 and measuring the values of the electrical resistance

  in freshly mixed concrete between

  electrodes arranged at the same distance W as the dis-

  reciprocation of the rods 24 and 24 'of the drills.

  Similarly, to obtain a concrete having the same conditions or conditions similar to those of the sample, the proportions of raw materials for the soil stabilization cement to be used during the actual formation of a soil are determined beforehand by calculation. stack, that is to say that we calculate the quantity of cement milk to be delivered last on the basis of the quantities of cement and water in conformity

  with, for example, the amount of pulverized soil

  on the basis of the diameter of the drills 23 and 23 'and

depth.

  Once a quantity has been placed

  In the soil shown in FIG. 2, a stream of soil consolidation cement is mixed with the electrodes 27, 28, 29 and 27 ', 28', 29 'mounted on the stems. 24 and 24 '

  forests, and the values of the resistance

  this electric fresh cement consolidating the soil,

  the electrodes 27 and 27 ', 28 and 28' and 29 and 29 'in identical vertical positions, by means of

  resistance gauges 32, which are arranged

above said electrodes.

  Experiments have shown that the

  of the electrical resistance of a mixture

  2000 g of sand and 400 g of water were equal to 770 °, when measured with two electrodes 10 cm apart, while the measured value was 260 '2 when g was added. cement to the same mixture and that was carried out

  a mixture for one minute, and that the value

  when the latter mixture was subjected to a mixing action for a period of five minutes. It was also found that the addition of g of sand, 400 g of water and 200 g of cement and mixing them for 1 minute provided an electrical resistance value of 150 q between the electrodes, while the mixture of the whole for a period of 5 minutes provided a value of 130 Q It can be seen that the addition of cement to a mixture of sand and water reduces the value of the electrical resistance between the electrodes and that a mixture more intimate

* cement mortar homogenizes the ingredients and provokes

  that a further decrease in the value of the

electrical resistance.

  Inasmuch as the concept of the present invention is well understood, it can be seen that the drills are not meant to be limited to dual type drills.

  The implementation of the apparatus described above

  according to the present invention

  the advantage not only of determining effectively

  if the work in progress progresses satisfactorily, but also, lo =, a confirmation of work done incompletely, to be able to inject a chemical supplement and to check the direction of escape of the chemical. for example, it prevents the pollution of drinking water,

of a river or the like.

  The following specific exemptions describe the more detailed construction and effects

  obtained according to the invention.

Example l

  As shown in Figure 3 (a) and 3 (b)

  sand 42 having a moisture content of

  10.5% tee in a plastic box 41 and a sand gel 43, with a diameter of 10 cm and a length

  1 cm was buried in the sand.

  arranged at identical intervals following the

  diametral direction of the body of the gel 43 and each

  The trode was connected to a resistance

  Kohlrausch Bridge (type BF-62 A manufactured by the

  Shimazu Manufactory) The resulting behavior

  both resistance values were measured as

  4 In this figure, the curve A represents the resistance behavior obtained in

  the case where the electrode was arranged in the central part

  gel and the other electrode was displaced

  the directions of expansion of the diameter (as

  represented by the arrow BA), then measuring the values

  their resistance, whereas curve B represents

  the case where the electrode was fixed in a position

  B in Figure 3 (a) and where the other electrode was moved

  in the direction of the arrow located in the

  of the gel so as to be separated from point B.

  As is clearly visible on the

  4, the gel has a very low resistance value and a marked behavior and variation in the value of the electrical resistance at

  level of the boundaries between the body of the gel and the sand.

  It has been confirmed that this phenomenon occurs in a similar way even if the sand is replaced by clay or granitic ground spray. It has also been discovered that the depth has practically no effect in any case, when a current of measured

crosses the body of the gel.

Example 2

  A glass-based test gel was made

  soluble and sand in a three-layer structure.

  in a cylindrical shape with a diameter of 15 cm and a length of about 30 cm, and for which the concentrations of the water glass in the central part (up to the distance corresponding to a radius of about 2 , 5 cm), in the central part (up to the distance corresponding to a radius of about 5 cm) and in the outer peripheral part were respectively equal to 38.6%, 23.9% and 11.2% Ce test gel was

  introduced into sand with a moisture content

  10.3%, and changes in the value of the

  sistance corresponding to the following distances

  the diametrical directions from the central part

  the body of the gel were measured and are represented

  in the table below.

  sultant is illustrated by the solid line curve on

Figure 5.

  There has been virtually no change

  cation of the electrical resistance between the different

  three-layer soluble-glass body layers.

Example 3

  The same procedure as that used in the case of Example 2 was again implemented, except

  that the similar body of the gel, as used in the example

  ple, was buried in pulverized granitic soil

  with a moisture content of 17.3% and the results obtained

  are shown in the table below.

  The resulting behavior of the resistance value is illustrated by the line of broken lines Distance Left side Right side l (cm) I x (102 n) (X 102 È)

2.5 1 0.13 0.13

3.5 1 0.20 0.21

1 0.23 0.26

6 1 0.35 0.36

7.5 0.45 0.47

8.5 13.2 1 12.8

, 5 19.8 21

  30 d 32 in Figure 5 Distance Left side Right side (cm (X 102 s) (x 102 Q)

2.5 0.17 0.17

3.5 0.35 0.29

0.48 0.4

6.0 0.77 0.62

7.5 1 0.75

8.5 16.9 17.2

, 19.8

, 31 34

  From these results it can be seen that in

  the values of the electrical resistance on the site

  of work, it is possible to obtain practically

  bearing as shown in Figure 6 and thereby

  to clearly determine the extent of the body of the gel.

  In the figure, it can be seen that a curve A represents a soil which is not subjected to any treatment, and that a curve B illustrates the presence of a body of a

  at a certain point, by means of the repetitive behavior

  d by the line formed of broken lines The curve

  C represents the resistance values measured in

  both of the central part of the body of the gel, this

  be used to confirm the limited extent.

Example 4

  As shown in FIG. 7, control devices Q and R are inserted at locations

  which are separated from an opening P of cementation

  the introduction of a chemical product at a distance of

  these different, and a voltage was applied between P and Q and P and R, thereby measuring the electrical resistances at the measuring terminals, as this

  is shown in the table given below.

  ra that the distance P-Q was equal to 1 m and that the distance P-R was equal to 75 cm The maximum depth of the stems from the ground level was 4.5 m and

  measuring points 1, 2, 3, 4 and 5, 6, 7, 8 of the dis-

  positive control Q and R respectively were

  killed at identical intervals of 50 cm from the deepest points The target soil consisted of the embankment or bench extending from the soil surface to a depth of 85 cm, clay mud up to at a depth of 310 cm and sand of medium size to a depth of

450 cm.

  As is clear from the table

  indicated below, the limits of the injection zone of the

  chemical product can be determined in a way that

is extremely clear.

  Quantity Resistance (ohms) injected _ Secti p-1 p-2 p-3 P-4 P5 P-6 P-7 P-8 1-5 2-6 3-7 4-8 measure

  0 225 250 270 250 230 245 260 370 76 124 174 270

  49 72 90 77 54 76 89 143 86 141 173 200

  48 71 97 75 50 74 89 120 86 142 174 158

  45 69 98 74 49 68 88 90 84 160 138 116

  44 69 103 76 45 70 85 85 83 132 188 156

  43 70 103 78 38 8.6 63 83 77 71 164 156

  240 43 68 112 80 37 7.5 65 72 74 73 172 148

  260 43 68 94 14.6 40 8.2 72 6879 73 151 81

  280 43 9.7 20.513.8 39 8.3 6770 78 14 73 79

  300 42 9.9 8.9 11.8 37 8.267 6877 13.6 69 76

  320 43 8.6 8.3 9.6 37 7.7 60 6145 12.1 6777

  340 9.8 7.5 7; 6 9,738 7,968 70 43,112 69 70

Figure 8 trant another form

is a schematic diagram

of the present invention

  invention implemented according to the process described above for

  example A hole in the soil is

  means of a cementation tube used to perform this drilling and having a drill and using a jet

  air or water under high pressure, and

  the drilling operation when the desired depth

  If a chemical is found to be

  at a high pressure of about 5 to 150 106 Pa from a side nozzle of the grouting and piercing tube, and the soil particles in the direction of displacement of the pressurized fluid.

  are high while the chemical is entering

  between the particles and solidifies The piercing and cementing tube is raised or lowered while rotating or rotating, and a stabilized zone of a range depending on the injection pressure and / or the coefficient In this case, the permeability of the soil particles is formed by inserting measuring electrodes E into

  predetermined measures to measure the resistance

  during the execution of the work, he

  is possible to do a perfect job.

Example 5

  After the introduction of the detection tubes

  tion, a hole has been drilled in the correct position

  cementation for the injection of a chemical.

  In this case, although it was a standard practice to use

  a piercing tube used to carry out the injection with a chemical, the tube used

  additionally included an electronic signal

  a sensor located in a suitable location on its front end, and the value of

  the soil resistance R O continuously or intermittently

  tent, while the depth of the drilled hole increased, thus memorizing the values measured in a computer. Once the drilling operation is completed, one

  correctly used a solid chemical

  instantaneous or slow-solidification

  function of the soil structure and cement tube

  chemical injection was lifted continuously or intermittently during the injection.

  In this case, the electrical signals

  were permanently produced by the terminals on the end of the cementation tube for the injection of the chemical, so that the R value of the signal varying from time to time was recorded

  sensors located on the detection tubes

  in the surrounding area and was sent permanently

this to the computer.

  More specifically, as shown in FIG. 9, on which we see that

  Detection II and III are located in

  metrically with respect to a cementing tube I, being at a distance of 50 cm from the latter, the cementing tube I was raised in increments of 50 cm so that the amount of the initial injection of OO 1160 2 was sent while the outlet of the cementation tube was in position i, the following 160 ft 320 were sent while said outlet was in position ii, while the following quantity 320 xv

  460 ú was sent to heading iii, that the quantity

  following tense 480 -1 640 9 was sent to position iv, and so on (the sensor position on the

  cementation 1 was naturally relieved from a to d by

  liers) and the variations in the quantity

  injecting chemicals and electrical resistance

  cudgel. The variation of the value of the resistance was introduced successively into the computer, which calculated and displayed the values of the resistance R introduced permanently on the basis of a resistance value R 10 corresponding to the formation of a gel body at 100% in the soil By representing the

  values on a display device, a paper

  recording or the like in the form of a sectional view

  lengthwise on both sides of the cementing tube

  In order to introduce the chemical, it is possible to clearly represent the penetration of the chemical, as shown in FIG. 10. Thus, a remarkable practical effect is noted in the fact that

  when the position of the detector tubes is changed

  In this way, it is possible to determine or confirm the injection condition of the chemical, layer by layer, and that it is therefore possible to

  take responsibility for the result of the work

done.

  In FIG. 10, the hatched surface

  in G represents an ideal injection zone and the surface surrounded by a dashed line is a

  graphical representation of the injection zone obtained

  as a result of effective cementation Similarly the line formed of a mixed line represents the sections of the gelled parts in the same direction and which have

  obtained as a result of the actual operation of exca-

vation.

Claims (4)

  1 Method for controlling an injection zone   a cementing agent in the soil, to ensure   controlling a zone (21) for injecting a cementing agent during a soil stabilization process, characterized in that it comprises the phases   which consists of having at least two electri-   trodes (27,28,29; 27 ', 28', 29 ') in an area to be controlled; sending a current to said electrodes from a power supply source (31); and   to measure (32) the variation of an electrical resistance   between said electrodes (27,28,29; 27 ', 28', 29 ').   The process according to claim 1, wherein   characterized by forming at least one control hole in the outer volume of a predetermined zone (21)   injection of a cementing agent in the center of the   which is located an injection hole of said agent of ci-   ment, and that at least one electrode (27,28,29; 27 ', 28', 291) is disposed in said injection hole of the cementing agent and said control hole, which has the effect that the cementing operation in said area   (21) predetermined injection is controlled according to   change in the value of the electrical resistance between said electrodes.   3. Process according to any one of the claims   1 or 2, characterized by measuring the variation   of a value of the electrical resistance between   corresponding electrodes (27,27 ', 28,28', 29,29 ') made   part of the electrodes (27,28,29; 27 ', 28', 29 ')   in several control holes.   4. Process according to claim 1, characterized   rised by measuring the value of the electrical resistance   of an electrically conductive subterranean body (43) located between a plurality of electrodes arranged in a control hole.   A method of controlling an injection zone of a soil cementing agent, characterized in that it includes a measure of soil resistance at   means of implementing the operating phases   at least having a pair of electrodes (27, 28, 29; 27 ', 28', 29 ') in positions on both sides of an injection zone (43) of the cementing agent   during a soil stabilization process, to   to measure the value of the electrical resistance of an unsolidified cementing agent between said electrodes,   and comparing said measured value with a previously   properly measured electrical resistance of an   made in conditions similar to those   said cementing agent, so as to provide advance   this, while said cementing agent is in the state   not solidified, its resistance after solidification.   6 Apparatus with a cementation tube for injecting a chemical product and intended for use in soil improvement, characterized in that it comprises: (a) a pivot comprising a closed electrical circuit between at least one terminal (1) arranged in a   head of said pivot and a cable connector (3)   in a central portion of the lower end of said pivot, through a sliding broom (4), and a cable; (b) a rod (11) of the cementation tube including a cable conduit (5) having another cable connector (6) at each end thereof   and located in a centered position in a multi-element tube   concentric tiples; (c) a stem of the cementation tube equipped with an electrode (30, 30 ') having another cable duct also having another cable connector at each of its ends and located in position   centered in another multi-element tube   and an electrode placed on an outer wall.   said tube and connected to a lead wire extends   from another cable connector; said pivot, said rod of the cementation tube and said rod of the cementation tube equipped with a   electrode being suitably connected reciprocally is lying.