CS9792A3 - Process for producing a sealing underground wall - Google Patents

Abstract

Single-phase method, in which soil material is removed from the wall of a trench (1), filled with a self-hardening sealing-wall mass suspension, by a trench wall cutter (2) known per se and, in a mix with the sealing-wall mass suspension, is pumped as lining suspension out of the trench, the mix is screened (17), and the fine portion of the mix lying below a predetermined coarse-grain size is used together with new, freshly cut sealing-wall mass suspension to produce a re-filling suspension which is pumped into the trench (1) in a re-filling quantity corresponding to the removal of the soil material. <IMAGE>

Description

Ο ΓΟ

OC -92

A method of producing a sealing underground wall

Technical field

BACKGROUND OF THE INVENTION The present invention relates to a process for the production of a sealing underground wall by a single-phase peetup.

BACKGROUND OF THE INVENTION [0002] In the manufacture of sealing sub-walls, the mass of the sealing walls is incorporated into the soil pockets, for example, as luminescent elements that surround them, and prevent any possible soil contaminants from spreading through the groundwater or into the trenches or into the ground. surface mining as a wall will reduce larger lower groundwater levels and groundwater quantities transported.

It is known that the sealing underground walls are produced in a one-phase manner by digging a pocket containing the bentonium-protective suspension and the cement which serves as a protective liquid during the excavation and after the excavation is completed by means of a grab excavator. it hardens and acts as a sealing mass / Mesack, Ruppert, Simons "Herstellung von Dichtungs-schlitzwSnden im Einphasenverfahren", Tiefbau /1979/paststr.601-605 / · It is recommended to add bentonite to the suspension in case of dredging and cement retardant.

As a drawback, it is important to enrich the mass-sealing walls during dredging or erosion with soil particles from the excavated material, such as clay and sand, so that the suspension solidifies and hampers further work. the mass permeability of the wall is increased. Therefore, it is recommended that the suspension be continuously monitored and the limit values observed to avoid increased enrichment. DE-PS 36 33 736 discloses dry mixtures for the single-phase production of sealing underground walls, which essentially consist of swellable clay material, blast furnace flasks and accelerators for blast furnace slag and up to 25% by weight of inert fillers. In the manufacture of the sealant mass, customary additives that influence the flowability of the mixing, consistency or solidification can be added. The effect of thixotropy should be less than that of traditional masses. In a two-phase process whereby a bentonite suspension is used as a protective liquid during excavation, which is then extruded by a self-curing bentonite-cement suspension, a milling technique is increasingly promoted. The soil material loosened and comminuted by the cutting coils is mixed in the pocket with the bentonite suspension, the soil-containing material is aspirated and pumped into the treatment plant. In this treatment, the excavated material is carefully and lengthily separated from the bentonite suspension by a costly vibration system in combination with the cyclones. The purified suspension is then reused. The excavated material is put through a dump. The operation using a milling technique with known sealant masses suitable for carrying out a single-phase process will wreck each time to partially seal the sealing portions (especially the metallurgical sand) at each pass through conventional treatment plants and therefore be used only in a two-stage process . In the process for the production of a sealing wall known from LE OS40 08 207, which is approaching a single-phase process, the excavation is first carried out in the usual manner by milling the underground wall, while the ground pocket is protected by bentonite suspension. Binders and solids are then directly added to the bentonite suspension in the pocket and the sessile is pumped through the milling machine for mixing with the front pump. SUMMARY OF THE INVENTION It is an object of the present invention to provide a process for the production of a sealing sub-wall by a single-phase process by which sealable sealing walls can be made with a higher waterproofness, better resistance to erosion and chemicals, and particularly low costs.

The essence of the invention further

This object is solved by the feature of claim 1, advantageous / embodiment of the invention.

Since the excavation does not involve the use of grabs, while the milling technique is used, it is possible to re-store the fines of the soil for the first time in the subsoil. By the particular adaptation of the sealant mass, surprisingly large amounts of soil fines can be used without compromising the desired properties of the fresh slurry serving as a protective slurry and the mass of the sealant wall to be hardened. and chemi-kaliim. Also, the throughput coefficients are improved. Surprisingly, the grain sizes of the excavated ground material up to, for example, 1-2 mm do not pose any problems, so expensive cyclone treatment separators, known from the milling techniques, can be omitted. With the aid of the simple sieves, it is possible to separate the unusable, usually in the smallest amount, the coarser part of the excavated soil material and deposit it.

According to the invention, it is also contemplated that the usable sludge adhering to the coarser portion is rinsed and added along with the rinse water as the distribution water to the sealant mass. The purpose of the invention may be to use known dry mixtures for additional filling of the sealing wall material. These are optionally supplemented with a chelating agent for the polyvalent cation / or dispersant to capture fines (1 mm) of the excavated earth and / or additionally added, fine, other inert substances such as calcium flour, quartz sand , waste glass meal. the amount of the chelating agent is adjusted depending on the active multivalent cations, which come, for example, from the blast furnace slag accelerator present in the dry mixture and / or from the discharging water and / or the excavation of the earth and / or the additional inert substances present and the workability the suspension remains at a sufficient fluidity of at least 8 hours. The addition of a dispersing agent is carried out in such a way that the deliberately added, fine inert substances or fines (1 mm) of soil in an amount up to 1,600 kg / m 2 which are not disposed of in the landfill can disperse that the workability (e.g. passage of sieve / high thickened sludge.

Suitable chelating agents are, for example, polyphosphates or hedroxycarboxylic acids, their lactones or their alkali metal salts, in particular sodium gluconate.

Suitable dispersants for the collection of fine sands or powdery earth from quartz, limestone or claystone are, for example, polyacrylates, especially water-soluble copolymers with M = 1,000 to 6,000 or Na-polyacrylates with M = 10,000 to 20,000. The addition of fine inert substances is carried out when the trench does not contain a sufficient amount of fines to keep the grain of, for example, 0.2 to 1 mm in float, and to incorporate soils into the mass filled with the most grainy grains. Example of Embodiment of the Invention

Particularly suitable dry mixes for the process according to the invention, suitable for sealing wall materials, have the following composition: 10 - 30 wt. activated Ca-bentonite / " Na-Bentonite " of metallurgical sand / EOT / milled to a fineness of 2000 to 6000 cm2 / g 1 - 5 wt. accelerators for metallurgical sand, such as grades, lime or calcium sulphates 0 - 1 wt. chelating agent for polyvalent cations 0 - 5 wt. a dispersing agent for capturing fines (< 1 mm) of excavated soil or additionally added fine inert substances (such as limestone, quartz sand, waste glass) (0-4 wt%); reactive silicic acids

The dry mixture is treated with service water using a customized feed of shear energy to the suspension with the water-sealant mixture /

W

DWM - Quotients / 3.5 - 1 - 5 Mix with inert portions, from excavation and, if appropriate, from the addition of an inert substance such that the water-solid quotient (W) is obtained. Λ o_ - / az, 25 ·

P with solids = mixture for sealing wall + inert parts.

The method according to the invention is further explained by means of a schematic drawing.

In the schematic cross-sectional view of the pocket 1, there is a well known subterranean wall milling cutter 2 whose pump 2 is used to pump a constant volume through the suspension system 4 - 6 in the direction of arrow 2 ·

By means of a piping system 6 (not shown), a pump 7 is dispensed from a mixing tank 7 equipped, for example, with a non-shear agitator 8, the content of which is mixed almost homogeneously with the arrow 2, a certain amount of additionally added suspension into pocket 1.

When not milled, the pumped volume quantity of the suspending suspension corresponds to the volume of refilled suspense.

If it is milled, the amount of reinforcing suspension that corresponds to the small milled amount, i.e. the milled amount of soil, is exhausted and additionally supplies a quantity of supplementary suspension that corresponds to the small milled amount of soil + milled cavity in the ground. 7 if the soil does not show any coarse proportions, for example above 2 mm, it is only necessary to drain! a plurality of which is set to a certain pump capacity and, after the addition of DWM, to pump them out again, which can be done by checking a liter weight of slurry of 14.19.6 slurry in the pipe system.

Preferably, by means of the conveying system 10, the shearing mission 15 is filled with a known dry mixture of the wall-sealing material which is withdrawn from the silo 11. In addition, the water 15 is fed into the mixer 15 via line 12 in the direction of the arrow. The shear-mixed suspension is brought to the mixer 15 via the pipe system 14 in the direction of the arrow 16 of the mixing tank 7.

The reinforcement slurry is pumped through the pipe system 4 into the screening apparatus 17. The coarse fraction (e.g., over 2 mm / reinforcement slurry) is separated by the sieving device 17 and removed from the slurry treatment plant (in the direction of arrow 18). The coarse fraction may optionally be used for other building purposes.

The fine grain portion of the stiffening slurry obtained in the sieving device 17 is pumped through the duct system 19 in the arrow 20 direction to the mixing tank; in this case, it can be transported to landfills (in the direction of arrow 21) in the event that too much fine grain is omitted, for example, when no coarse grains are present in the milled soil or the sealing wall mass is present it should additionally add other inert material.

Advantageously, from the water pipe 12 of the branch pipe 22 through which the utility water of the screening apparatus 17 is guided in the direction of arrow 23, for example, to rinse the coarse grains.

The fluidity control of the slurry and the liter weight of the presently occurring amount of chelating agent additive or dispersant or additive additive, can be added, for example, to the mixing tank 7 in separate portions.

The present invention thus provides a single-phase process which, in particular, guarantees low landfill costs and, moreover, requires a small amount of dry mix for the sealing walls. It was surprising that considerable amounts of excavated soil material could be used again without reducing the watertightness of the sealing underground walls.

Claims (13)

-8- 'Ί> ι / 37-92 PAIEHIOPO A process for the production of a sealed sealing wall by a one-step process in which ground material from a wall of a filled-in self-curing sealant suspension material is discharged by a well-known underground wall cutter and in a mixture with a sealant wall suspension, the pocket is depleted as a reinforcement suspension. the mixture is sieved and the finely divided slurry is used in the production of the supplementary slurry, the size of which is below the predetermined grain size, together with a new, freshly prepared slurry for the sealing walls, and pumped into the pocket in an amount corresponding to the amount land material · Method according to claim 1, characterized in that the coarse grain portion is rinsed and the rinsing material is fed to a fine fraction or supplementary suspense. A process according to claim 1 or 2, characterized in that a supplementary suspension is used which has a fines content of 400 to 1800 kg / m 2. Process according to one or more of Claims 1 to 3, characterized in that a fine fraction is used, the grain size of which is below 2 mm, in particular below 1 mm. Process according to one or more of Claims 1 to 4, characterized in that the added inert substances are used as fines for the production of a supplementary suspension. Process according to one or more of Claims 1 to 5 - 9 - characterized in that, in the manufacture of the filler suspension, in order to ensure sufficient workability, the forming agents are added in an amount dependent on the content of the active, polyvalent cations present in the additive. suspending agents. 7. A process according to claim 6, wherein the polyformers used are polyphosphates or hydroxycarboxylic acids, their lactones and their alkali metal salts, in particular sodium gluconate. Process according to one or more of Claims 1 to 7, characterized in that dispersants are used in the production of the additive mixture in a quantity dependent on the content of fine fines to ensure sufficient workability. Method according to claim 8, characterized in that polyacrylates are used as inert materials or as inert substances when using fine sand or fine sand from quartz, limestone or claystone, namely water-soluble copolymers with M = 1,000 to 6,000 microns Ua -Polyacrylates with M = 10,000 to 20,000 · Process according to one or more of Claims 1 to 9, characterized in that the following dry mixtures are used for the production of the filling suspension: 10 - 30% by weight. activated Ca-bentonite (" Na-bentonite ") (72-90% by weight); % of metallurgical sand / HOS / ground to a fineness of 2000 to 6000 cm &lt; 2 &gt; accelerators for metallurgical sand, such as cement, lime or calcium sulphate 0 - 1 wt. a gelling agent for polyvalent cations 0-5% by weight; a dispersing agent for collecting fine particles of -10-41 mm / excavated soil or additionally added fine inert substances (such as lime, quartz sand, waste glass / 0-4% by weight); reactive silicic acids. Process according to one or more of Claims 1 to 10, characterized in that an additional suspension with water / mixture mixture quotients for sealing walls 3 to 1.5 is used. Process according to one or more of Claims 1 to 11, characterized in that additional suspensions are used, which have a water-solids quotient of up to 0.25. Use of a supplementary suspension in a single-phase process for the production of a sealing underground wall, comprising 400 to 1600 kg / m @ 2 of fines with a grain size of recovered soil material below 2 mm.