CH200314A - Process for consolidating and sealing permeable soils, finely fissured rocks, porous masonry, concrete and foundations by means of injections. - Google Patents

Description

  

  Process for consolidating and sealing permeable soils, finely fissured rocks, porous masonry, concrete and foundations by means of injections. The proposal to consolidate permeable soils by injecting a chemical solution using sodium silicate as a base is not new. It is also already known to precipitate a silica gel from solutions used for such purposes by adding an electrolyte (salts or acid).

   In all existing methods, however, no consideration has been given to the fact that the gel obtained in this way consists partly of soluble and partly of insoluble compounds. It has also not yet been possible to produce a silica gel of greater hardness in the soil in a rational and economically applicable way. It has also been proposed to inject two different solutions one after the other, and when they are mixed in the injection zone, the silica gel is excreted.

    However, it shows that the two solutions are often mixed up unevenly and that only part of the cavities in the bottom are filled by the silica gel. The solutions used up to now mostly result in a more or less strong precipitation, which partially prevents the progress of the injection by the formation of a filter skin in the soil.



  The present invention relates to a method for solidifying and draining permeable soils, finely fissured rocks, porous masonry, concrete and foundations by injections according to wel chem as an injection means a clear, colloidal sodium silicate solution is used, the stability of which is reduced by adding an acid that the addition of at least one soluble heavy metal salt causes the precipitation of a silica gel in a predetermined time.



  Since the solution used according to the procedure is clear and shows no precipitation, it offers a very large radius of action in the soil.



  If a certain amount of an electrolyte is added to sodium silicate, a gelatinous precipitate results. In the present process, the existing pH content of the sodium silicate is reduced by an acid in order to obtain a weaker alkaline solution, which zer by adding a suitable heavy metal salt (iron, copper, lead, zinc, or the like.) As an electrolyte interferes and solidifies into a gel.

   By lowering the p11 content, the waterglass solution becomes more sensitive and with correspondingly precise metering of the electrolyte, which can be added at the same time or later than the acid. solidification to form a gel can be caused in the soil at any desired point in time. Under certain circumstances, two or more different metal salts can also be used together.



  The gel obtained in this way hardened after a long period of time due to the release of water and the transformation of the ultramicrons into ultra-microscopic crystals. For example, quartz crystals were found after storage for two months at normal temperature.



  Two practical application examples are given to explain the process: Implementation example <I> I: </I> A fine floating sand base was consolidated and sealed according to the present process in order to enable excavation work for the foundation of a water purification system. The floating sand had a grain distribution curve in which <B> 80% </B> of the grains were smaller than <B> 0.11 </B> mm, <B> 50% </B> smaller than <B> 0.098 < / B> mm, <B> 30% </B> smaller than- <B> 0.090 </B> and <B> 10% </B> of the grains were smaller than <B> 0.076 </B> mrn.

    The permeability of the de-q sand was at a temperature of <B> 15 'C: 9.1 </B> X <B> 10-1 </B> cm <B>' </B> / minute. The injected clear, colloidal solution consisted of industrial sodium silicate <B> 36 '</B> B6 diluted with water <B> (100 </B> parts by weight sodium silicate and <B> 100 </B> parts by weight water), to which a solution containing hydrochloric acid and copper sulfate, namely one volume of solution to two volumes of sodium silicate solution, was added.

    By. the hydrochloric acid reduced the stability of the sodium silicate solution to such an extent that the copper sulphate caused the precipitation of a silica gel in a predetermined time. The injected solution stiffened into a silica gel after about 47 minutes in the ground.



  A circular cylindrical zone and a base plate were consolidated by a double series of injections in order to prevent the remaining sand from flowing in during the excavation work. The outer injection zone, i.e. the row of injection tubes, was initially injected with only very weak pressures (beginning <B> 0.5 </B> atmospheres, end 3--4 atmospheres). In the case of the inner injection zone, the pressures rose to <B> 7-8 </B> atü after a short time, which means that the soil was already showing great resistance to these injections as a result of the previous treatment.



  In this way, the foundations were carried out around <B> 15 </B> meters below the groundwater level, avoiding caesun work without special water maintenance.



  <I> Embodiment H: </I> Very porous concrete samples on a dry dock were consolidated and made impermeable according to the present method. The concrete of the dry docks, which was gradually attacked by sea water, had a permeability of about 1 before the treatment. 10-3 cm / sec. on. The above solution was injected under moderate pressure. After the treatment, the concrete showed a permeability below <B> 5 </B> atü water drug of about <B> 1. 10-8 cm / sec.

 

Claims (1)

<B> PATENT CLAIM: </B> Process for the consolidation and sealing of permeable soils, finely fissured rocks, porous masonry, concrete and foundations by means of injections, characterized in that a clear, colloidal sodium silicate solution <B> g </B> is used, the stability of which is so reduced by the addition of an acid that the addition of at least A soluble metal salt causes the precipitation of a silica gel in a predetermined time. SUBClaims: <B> 1. </B> Method according to patent claim, characterized in that, at the same time as the acid is added, a soluble metal salt is added. 2. Method according to patent claim, characterized in that after the addition of the acid, a soluble heavy metal salt is added.