HU181284B - Method for constructing kerf wall particularly for side limiting working pit to be made in well-drained soil as well as apparatus for making kerf filling material particularly for carrying out the method - Google Patents

Description

István Bohn Certified Engineer 40%, Dr. Hajnal István Certified Engineer 20%, Transport and Metro Construction Dr. Zoltán Burián Certified Engineer 40%, Budapest Company, Budapest

Process for the construction of a slit wall, in particular for the lateral delimitation of a manhole in a water-permeable soil, and for the production of slit-fill material, in particular for the process

FIELD OF THE INVENTION The present invention relates to a method for laterally delimiting a pit to be formed in a water-permeable soil, and in particular to an apparatus for producing a filler material for carrying out the process.

In civil engineering practice, gap walls are often constructed to solve various construction tasks, which are usually used for waterproofing the sides of work pits. The filler is a post-solidifying sludge, the basic mixture of which consists of water, bentonite and cement. Depending on the application conditions, a curing delay additive (usually used in concrete technology) is also added to the mix. Examples of such agents are "Retardol", "Barralent", etc. and alkaline materials, e.g. sullen leachate.

The mixing ratio of water, bentonite and cement is known as the so-called "cement" and "bentonite" type during the entire slit cycle. handling - proper movement of the slit tool - and the so-called required slit filler material. final strength and waterproofing effect.

Theological parameters required during the slit process - in particular workability - generally demand contrary to what is required for the final state. The workability requires low viscosity and keeping the erection process below a certain threshold (about 10,000 g / m ² ) during the entire slit cycle, which is usually achieved by limiting the dry matter content. On the other hand, in order to provide the strength and waterproofing properties required from the final state, it is necessary to increase the dry matter content.

To resolve this contradiction, the above-mentioned curing agents, which have three properties, are added to the bentonite-cement-water mixture:

- the cost of acquisition, - the quantity required to produce a unit volume mixture, - a time curve 15 representing the delay effect.

The desired duration of the delay effect is determined by the time cycle of the slit process, so the suitability of a delay agent is primarily determined by this criterion. In practice, the cycle time required to produce up to 30 m deep, which can be provided by machines with a maximum capacity of 20, and the cycle time required to produce a continuous watertight wall from each of the catches in a medium bite sequence. operating time. According to experimental data, this value ranges from about 30 to 50 hours. During this period, the rigidity of the material mixture filled into the gap, when mixed by the slitting tool, should not exceed the above-mentioned threshold value of about 10,000 g / m ² .

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Below we compare the delay times available with the most commonly used delay agents and the cycle times of the bentonite-water-cement mixture without the delay agent. For the sake of uniform evaluation, the delay time is always defined as the time necessary to achieve a rigidity of 10,000 g / m ² . The water-cement factor (v / c) is always 4.35; the water bentonite factor (v / b) is 33.3. The results obtained are as follows (1 = delay time per hour):

masterbatch (water-cement-bentonite mixture without delayer): t = 8.7 hours Barralent 2.0% (based on cement) t = 15.7 hours Barralent 3.0% (based on cement) t = 23.9 hours Retardol 2.0% (based on cement) t = 14.4 hours “Lignosulfite” 1.5% (based on cement) t = 10.2 hours “Lignosulfite” 2.0% (based on cement) based) t = 24.4 hours.

comparing these values with the other two characteristics mentioned above: the purchase price and the quantity to be used, it can be concluded that none of the delay agents listed are capable of satisfying the requirements set at a high level. With regard to sulphite lime liquor, it is noted that its uncertain composition and variable quality make it possible to achieve its effect, and the delay factor is short and uncertain.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a solution for the preparation of slit walls which provides optimum workability of the fill material. parameters, as well as the required strength and impermeability properties of the crack wall as the end product can be rationally provided.

The present invention is based on the discovery that when a saccharide is used as a bond retardant, its composition and quality are constant, the delay factor being much smaller than that of the previously known similar materials in a unit volume cement-bentonite-water mixture. better quality and more economical.

Based on this discovery, the object of the present invention has been solved by a process of forming a gap in the soil which is filled with a post-curing agent containing cement, water, bentonite and a bond retardant, the essence of which is that 0.60-4.92% by weight of the saccharide, preferably 2-3% by weight, is added and the mixture containing the saccharide is introduced into the slot. A method of retarding, in a preferred embodiment of the agent is a C ₂ H ₂₂ 0i I (sucrose).

The components of the masterbatch filler material used in the process of the invention may vary within the following quantitative limits:

Weight Ratios:

Water Cement bentonite 10 1.65 0.38 to 10 3.20 0.75 to

For this base mix, sucrose (Ci ₂ H ₂₂ O) should be added in an amount of 0.60% to 4.92% o by weight, depending on the desired delay time, which may be from a few hours to about 50 hours. It will be appreciated that other disaccharides or monosaccharides may be used as the linkage retardant in place of the sucrose of the disaccharides.

With the filler materials of the above composition range, a crevice wall can be made in all types of water-permeable soil, from coarse gravel to fine sandy sand. A water barrier wall of more than 28 days of age achieves a water barrier of greater than k = 10 ' ⁷ m / s and a strength of

It can range from 100 to 2000 kN / m ² .

The accuracy of dosing is very important for achieving the desired effect of the delaying agent. In view of this aspect, a slurry sludge preparation apparatus of the present invention has been developed having a mixing tank for mixing water, cement and bentonite, and a dispenser for feeding a bond delaying agent, and having a knife delaying device for dispensing a mixing container over the mixing tank. that the metering tank has a gain of release valve ³⁵ to the dosing tank inlet valve and the agent; a fluid level sensor in the mixing tank which is operatively connected to the discharge valve; the liquid container has two liquid level sensors spaced vertically above each other; the lower fluid level sensor being in communication with both the inlet valve ⁴⁰ and the outlet valve to cause their simultaneous or substantially simultaneous operation; and the upper fluid level sensor is operatively connected to the inlet valve. According to a preferred embodiment of the apparatus ⁴⁵ , the inlet valve and the outlet valve are pneumatic valves comprising a compressed air operated resiliently deformable material hose or the like, which is connected to a compressed air source ⁵⁰ such as a compressor. It is also desirable to have at least two air ducts from the discharge valve and at least one air duct from the discharge valve, which passes into an electromagnetic valve ⁵⁵ actuated bypass valves (comprising electromagnetic coil and iron core); connecting the bypass valve of the exhaust duct extending from the exhaust valve to the compressed air source; and this air line is connected to the other two flow valves via additional air lines ⁶⁰ . In a further preferred aspect of the invention the liquid level sensing electrodes, which are by way of electrical cables in connection with the electron ₆₅ netic permeability valves assigned to them under mL-2,181,284 the electric control system of the liquid and the electrodes in contact with avoiding or contact termination of the circuit closing and interruption is constructed in a productive manner. Finally, a further embodiment of the apparatus is characterized in that the metering container has an upper cylindrical portion and a lower conical portion; the outlet valve is connected to a protrusion of the lower conical portion, or / and the outlet valve is arranged above, or at least partially extending into, the cylindrical portion.

Advantageous effects of the invention may be summarized as follows:

reducing the energy required to move the slit tool and the loss of slit filler, on the one hand, because the more plastic material flows back into the slit (less material gets into the waste), out of the soil particles highlighted with the slit tool; on the other hand, because the plastically-conductive material for a prolonged period of time also reduces the loss of material due to double-grip volumes along the bite catch. A further advantage is that the slit rate increases because the time required to move the slit tool is reduced due to the lower resistance (less rigid) slit filler, thereby increasing slit performance and thus making work more economical. By extending the shelf-life of the substance, so-called the length of the board, which can be opened at the same time, is a further factor contributing to the economy.

Note that about 2% of the weight of cement presently used in sucrose, which is about one-tenth the amount of cement retarder used today, is t = 22.3 hours for identical bentonite, water and cement. In addition, sucrose is not subject to quality fluctuations and the expected results are always assured. In addition, sucrose itself is significantly cheaper than other cohesive retardants.

The invention will now be described in more detail with reference to the accompanying drawings, which illustrates a preferred embodiment of a device for making a filler material.

The apparatus has a mixing tank 1 for mixing and resting the bentonite and water, consisting of an upper cylindrical part 2 and a lower conical part 3. From the latter, a pipeline 4 protrudes from the latter and connects to a vortex pump 5 driven by a motor 6. A closure fitting 4a is inserted in the pipeline 4. From the vortex pump 5, a pipeline 7 is connected which extends into the upper cylindrical part 2 of the tank 1. Conduit 7 includes a closure assembly 7a. The container 1 stands on 8 legs.

Above the reservoir 1 is the dispenser, denoted by reference numeral 9, which has a dispenser 10 of about 20 to 50 liters. The latter also comprises a lower conical section 11 and an upper cylindrical section 12. An outlet valve 13 is connected to the conical portion 11 below. Above the reservoir 10 is an inlet valve 14, into which a pipeline 15 for supplying a liquid cure delay agent, such as an aqueous sucrose solution, opens from above. Valves 14 and 15 are connected to a bottom compressor as follows:

From the outlet valve 13, there is an air line 17 and 18, and from the outlet valve 14 an air line 19, which open into each of the flow valves 17a, 18a and 19a, respectively. An air line 20 connects the through valve 17a with the compressor 16. An air duct 21 exits the through valve 19a and is connected to the air duct 20. An air duct 22 is branched from the through valve 18a and extends into the air duct 21.

In the upper cylindrical portion 2 of the container 1, preferably in its upper region, there is an electrode 23, which is connected to the flow valve 17a as a liquid level sensor 23a. In the container 10 of the dispenser 9, two further liquid level sensors 24, 25 are arranged at a distance x above each other in the vertical sense, the x distance being variable. The lower electrode 24 is connected by the electrical conduit 24a to the bypass valve 18a, and the electrical conduit 24b to the bypass valve 19a. The upper electrode 25 is connected to the by-pass valve 19a via the electric conductor 25a.

The pipe 26 is used for introducing bentonite and water into the tank 1 and the pipe 27 is used for feeding the cement at the same time.

The passage valves 17a, 18a and 19a have an electromagnetic structure: when the valve is energized, a coil of electromagnet draws in an iron core which opens a shut-off device; however, breaking the circuit will cause the valve to close. The valves 13, 14 are pneumatically actuated: they comprise a rubber hose in a valve body and when compressed air enters the valve body, it compresses (elastically deforms) the valve and closes; when the compressed air exits the valve housing, the rubber hose re-takes its pre-compression shape and becomes ready for material transport, thus opening the valve.

The apparatus operates as follows: according to the particular formulation, a predetermined amount of water is introduced through the tube into the container 1 and the water is circulated continuously by the vortex pump 5 through the pipelines 4 and 7 over a period of 1-2 minutes. add to the water (the arrow). After the total amount of bentonite was introduced, the material was stirred for a further 3 to 15 minutes. The mixing time between these limits should be set depending on the mixing temperature and the power of the vortex pump (12-30 kW).

The bentonite-water slurry, after mixing is completed, is so-called. maturation process. Maturation can take place e.g. by slow mechanical movement of the material in the maturation tanks, by air bubbling, by heating, or by the addition of substances (known in the art) which promote the hydration of the bentonite.

The bentonite-water suspension hydrated by relaxation is e.g. pumping it back into the mixing tank 1 and introducing it into the continuous circulation with the help of the vortex pump 5 in the same manner as the bentonite: slowly, gradually, ensuring the perfect dispersion of the cement in the mixture. After the addition of the total amount of cement, another 3 to 15 minutes of mixing is carried out.

The base mixture prepared as above may vary according to the particle size distribution of the soil containing the slit and the waterproofness and compressive strength to be achieved in the final state within the following weight ratio limits:

Water Cement Bentonite

1.90 from 0.33

4.00 to 1.02

The alapkeverékhez then added by weight of cement 0.60 ₀ ... 4.95% sucrose, by which the gap filling material is placed retaining properties in prolonged accordance plasticizable, and plastic.

In order to achieve the objective of the present invention, the dosage of the bonding delay agent requires the highest precision. This operation is carried out by means of an automated dispenser, designated 9 in its entirety, as follows:

adjusting the required distance x between the electrodes 24 and 25 in the empty container 10 and filling the container with bond delay material. The value of x is a function of the amount of water, cement, and bentonite added as described above, and corresponds to the amount of binder retardant (sucrose) required for a given dose of blend filler.

The position of the electrode 23 in the container 1, e.g. the height χ, measured from the lowest point of the container 1, is selected or adjusted to have a defined amount of cement-water bentonite suspension in the container 10 corresponding to the curing delay amount at distance x. Thus, when the level of the mixture in the tank 1 reaches the electrode 23, the circuit closes through the electrical conduit 23a, the bypass valve 17a opens, and the compressed air produced by the compressor 16, which holds the outlet valve 13 for a moment. by squeezing a rubber hose in its valve housing, it opens the discharge valve 13 as air flows out of its valve housing through the air conduit 17. Through the open outlet valve 13, the bond retardant flows freely from the container 10 into the container 1 containing the water-cement-bentonite mixture (c).

When the bond retarder in the container 10 drops below the level vj of the lower electrode 24, the circuit is interrupted, causing two effects:

the iron core of the through-flow valve 18a, so far energized, moves out of the electromagnetic coil, the valve opens, the compressed air from the compressor 16 enters and discharges through the conduits 20, 21, 22 and 18 (compresses the rubber hose). Thus, from the container 10, multiple bond delay agents cannot flow into the container 1;

- the circuit 19a also opens by interrupting the circuit, whereby the compressed air which has been held there so far and kept closed (compressing the rubber hose) is discharged through the air conduit 19. In this way, the valve 14 opens, from the conduit 15 (connected to the storage container (not shown)) to the empty container 10 (arrow d), the lower outlet valve 13 of which is then closed.

When the level V3 of the bonding delay agent fed to the container 10 reaches the upper electrode 25, the circuit closes again, the amplified pulse actuates the flow valve 19a, thereby closing the compressed air path to the inlet valve 14 into which the compressor 16 and through conduits 19, compressed air flows and closes the valve. The flow of the bond retardant into the reservoir 10 of the dispenser 9 is stopped and thus the reservoir 10 contains exactly the same amount of the bond retarder required for the batch of bentonite-water-cement mixture.

After addition of the bond retardant grains to the container 1 as described above, the water-cement-bentonite binder retardant mixture is further stirred for 3 to 15 minutes and then the finished gap filler material is conveyed to the site of use, for example by means of pumps known in the art. . Because the stiffness of the gap filler material produced in accordance with the invention during the time needed to move the slot tool in the slot (about 40 hours or less) does not exceed the prescribed threshold, the slot machine is unlike the currently used method for slitting. energy demand, the amount of filler material required per unit volume of slit, while increasing slit efficiency (through slit velocity and openable slit length). By keeping the filler material in the gap in a stirred state by moving the slot tool, the delay time t can be further increased relative to the value at rest, thereby increasing the advantages of the process.

The invention is, of course, not limited to the solutions detailed above, but may be practiced in a number of ways within the scope of the claims. It is important to emphasize that the apparatus is well suited for the manufacture of slit filler material not only with sucrose but also with other binder delaying agents.

Claims (7)

Patent claims: A method for constructing a slit wall, in particular a lateral boundary for a pit to be formed in a water-permeable soil, comprising the step of providing a slit in the soil which is filled with a curing agent comprising cement, water, bentonite and a curing agent. At 60-4.92%, preferably 2-3% o-saccharide is added and the saccharide-containing material mixture is introduced into the slit. 2. A process according to claim 1, wherein the bond delaying agent is C ₂ H _{2 20} O 1 (sucrose). Apparatus for making a gap filling material, in particular for carrying out a process according to claim 1 or 2, comprising a mixing tank for mixing water, cement and bentonite, and a metering device for feeding the curing delay agent, characterized in that a metering tank over the mixing tank (1). (10) a device (9) for dispensing a bond delaying agent having a valve (14) for introducing the agent into the dosing container (10) and a valve (13) for discharging the agent from the dosing container; the mixing vessel (1) having a fluid level sensor (23) operatively connected to the discharge valve (13); the liquid reservoir (10) having two fluid level sensors (24, 25) spaced vertically above each other (x); the lower fluid level sensor (24) being associated with both the inlet valve (14) and the outlet valve (13) to cause their simultaneous or substantially simultaneous but opposite operation; and the upper fluid level sensor (25) is operatively connected to the inlet valve (14). An embodiment of the device according to claim 3, characterized in that the inlet valve (14) and the outlet valve (13) are formed as pneumatic valves comprising a compressed air actuated hose of elastic deformable material or similar structure, which are provided on air lines (18, 19, 20, 21, 22) with a compressed air source, such as a compressor (16). 5. An embodiment of the apparatus of claim 4, characterized in that it comprises a discharge valve At least two air conduits (17, 18) for the discharge valve (17, 18) and at least one air conduit (19) for the discharge valve (14), which are arranged in electromagnetic actuated pass valves (containing electromagnetic coil and iron core) (17a, 18a); 10 19a) throat; connecting the through valve (17a) of the air line extending from the outlet valve (13) to the compressed air source; and said air conduit (20) via additional air conduits (21, 22) with the other two flow valves (18a, 19a) 15 are connected. 6. An embodiment of the apparatus according to any one of claims 1 to 5, characterized in that the liquid level sensors (23; 24; 25) are electrodes which are electrically conductive (23a, 24a, 24b, 25a). They are associated with the associated electromagnetic pass valves (17a, 18a, 19a), wherein the electrical control system is configured to cause the circuit to close or break when the liquid and electrodes come into contact or are removed. 7. An embodiment of the apparatus according to any one of claims 1 to 3, characterized in that the dispensing container (10) has an upper cylindrical part (12) and a lower conical part (11); the outlet valve (13) being the lower one It is connected to a protrusion of the conical part 30, or / and the inlet valve (14) is arranged above or at least partially extending therefrom the cylindrical part (12).