DK157204B

DK157204B - Process for stabilizing soils

Info

Publication number: DK157204B
Application number: DK411086A
Authority: DK
Inventors: Anne-Lise Berggren
Original assignee: Berggren Anne Lise
Priority date: 1986-08-28
Filing date: 1986-08-28
Publication date: 1989-11-20
Also published as: DK411086A; DK157204C; DK411086D0

Description

DK 157204 BDK 157204 B

Den foreliggende opfindelse angâr stabilisering af grunde, fx finkor-net jord eller 1er, ved fremkaldelse af sætninger i grunden sltedes, som det er angivet i indledningen til det efterfolgende selvstændige fremgangsmidekrav 1.The present invention relates to land stabilization, for example fine-grained soil or 1s, by eliciting basic sentences, as stated in the preamble to the subsequent independent process claim 1.

5 Ved belastning af fx lergrunde kan der opstâ store sætninger, som forpges med lerets lagtykkelse og stprrelsen af belastningen. Dette kan fpre til store total- og differentialsætninger, som kan skade kon-struktioner, der helt eller delvis er understpttet af leret. Af denne grund vil det være fordelagtigt at kunne frembringe sætninger i ler-10 grunden, fpr arbejdet med konstruktionen pâbegyndes, eller eventuelt fpr konstruktionen bringes i en sâdan stand, at den kan tage skade af sætninger i grunden.5 When loading, for example, clay soils, large sentences can occur which are mapped by the layer thickness of the clay and the size of the load. This can lead to large total and differential sentences which can damage structures that are fully or partially supported by the clay. For this reason, it will be advantageous to be able to produce sentences in the clay foundation, before the work on the construction commences, or possibly before the construction is brought in such a condition that it can damage the sentences in the foundation.

Kendte metoder til fremskyndelse af sætninger i en naturlig lergrund er fx fyldning (belastning af grunden med ballast), grundvandssænk-15 ning, vakuumpumpning, elektroosmose, vertikal drænering eller en kombination af to eller flere af de nævnte metoder.Known methods for speeding sentences in a natural clay soil are, for example, filling (loading the soil with ballast), groundwater lowering, vacuum pumping, electroosmosis, vertical drainage or a combination of two or more of the methods mentioned.

De nævnte metoder har aile sine fordele og ulemper med hensyn til forbrugt tid, effektivitet, bæreevne, simpel og generel anvendelighed.The methods mentioned all have their advantages and disadvantages in terms of time spent, efficiency, carrying capacity, simple and general applicability.

Især blpd grund eller 1er kan vanskeligt danne grundlag for et fun-20 dament for en bygningskonstruktion, fordi bæreevnen er for dârlig.Especially bare ground or 1s can be difficult to form the basis of a foundation for a building construction because its load bearing capacity is too poor.

Der er hidtil blevet benyttet forskellige metoder til at optage kon-struktions- eller nyttebelastningen, sa som pælenedramning, masse-udskiftning og kompenseret fundamentering.Various methods have so far been used to absorb the design or utility load, such as pile dredging, mass replacement and compensated foundation.

Ved sa ekstremt dârlige grundforhold som antydet, lader de ovenfor 25 nævnte metoder sig ikke altid gennemfpre, og de kan pi trods af gennemfprlighed være en ugunstig samt tidskrævende Ipsning for konstruktionen.In the case of extremely poor basic conditions as suggested, the above-mentioned methods may not always be implemented and, in spite of their transparency, they may be an unfavorable and time-consuming solution for the construction.

For en bebyggelse, der er fundamenteret direkte pl Ipse masser, hvor en stprre eller mindre del af disse l0se masser under grund- 30 vandsstanden bestâr af 1er, er der pâ lang sigt fare for sætnings- skader pâ bebyggelsen, dersom grundvandets tryk eller niveau fai- 2For a building that is founded directly on pulp masses, where a greater or lesser part of these loose masses below the groundwater level consists of 1s, there is a long-term risk of damage to the building if the pressure or level of the groundwater fails. - 2

DK 157204 BDK 157204 B

der, eller hvis trykket pâ kornskelettet forpges sâledes, at der opstâr sætninger i de Ipse masser.there, or if the pressure on the grain skeleton is tapped in such a way that sentences occur in the Ips masses.

Sorti omtalt i det ovenfor anfprte er det af stprste betydning at hindre sætninger i grunden, efter at denne er blevet belastet ved opfprelse 5 af bygningskonstruktioner eller andre former for belastning, som fx vejbygning etc. Som nævnt vil det være fordelagt at kunne frem-bringe sætninger i grunden, fpr denne beiastes, og hensigten med den foreliggende opfindelse er at tilvejebringe en fremgangsmâde af den indledningsvis angivne art, sâ at man pâ en hurtigere mâde kan 10 frembringe sâ store sætninger i grunden, at muligheden for ekstra sætninger, efter at denne er blevet belastet, bliver sâ godt som udelukket.Assortment referred to in the above-mentioned, it is of the utmost importance to prevent sentences in the ground after it has been loaded by concept 5 of building structures or other types of load, such as road construction etc. As mentioned, it will be advantageous to be able to produce basic sentences before it is claimed, and the object of the present invention is to provide a method of the kind set forth in the introduction so that, in a faster manner, such sentences can be produced in such a way that the possibility of additional sentences after has been charged, being virtually excluded.

Dette er ifplge opfindelsen opnâet ved hjælp af de ejendommeligheder, der er angivet i den kendetegnende del af det efterfplgende selvstæn-15 dige fremgangsmâdekrav 1 samt i de efterfplgende uselvstændige krav.According to the invention, this has been achieved by means of the peculiarities set forth in the characterizing part of the following independent method claim 1 as well as in the subsequent independent claims.

Et udfprelseseksempel for fremgangsmâden vil blive omtalt i det fpl-gende under henvisning til tegningen, pâ hvilken fig. la er et snit i en oprindelig lergrund, 20 fig. 1b viser fprste trin i fremgangsmâden med frysning af et pnsket omrâde af grunden, fig. le viser andet trin i fremgangsmâden, hvor det fryste omrâde tpes ved tilfprsel af varme, fig. 1d viser tredje trin af fremgangsmâden, hvor overskudsvand 25 trækkes ud af grunden, og fig. le viser et snit gennem den ved hjælp af fremgangsmâden be-handlede grund og den fremkaldte sætning i form af en forsænkning i grundoverf laden.An embodiment of the method will be described below with reference to the drawing, in which: FIG. 1a is a section of an original clay soil, FIG. Figure 1b shows the first step of the freezing of a desired area of the ground; 1c shows the second step of the process where the frozen area is tapped by application of heat; FIG. 1d shows the third step of the process in which excess water 25 is withdrawn from the ground, and fig. 1c shows a section through the ground treated by the method and the induced sentence in the form of a recess in the ground surface.

Ved behandling af fx den i fig. la viste lergrund 3 ved hjælp af 30 fremgangsmâden ifplge opfindelsen for at fremkalde komprimering og dermed sætning af lergrunden installeres koaksiale fryserpr 1, la i grunden 3, idet rprene 1 anbringes i grunden 3 pâ en hvilken som helst kendte mâde, fx ved nedpresning i lodret stilling i grunden.In the treatment of e.g. 1a, showing the clay ground 3 by means of the method according to the invention to induce compression and thus setting the clay ground, coaxial freezer pr 1, 1a is installed in the base 3, the rods 1 being placed in the base 3 in any known way, for example by pressing down vertically position basically.

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Fryserprene 1 tilf0res derefter kplemedium, dvs. en hvilken som helst kuldebærer, pâ en sâdan mâde, at et omrâde 2 af lergrunden 3 fry-ser. Ved langsom frysning vil vandet i leret fryse til iskrystaller, som vokser ved, at vandet trækkes ud af det ikke-frosne 1er nær/-5 mellem iskrystallerne. De voksende iskrystaller vil udpve et konsoli-derende tryk pâ de mineraikornsaggregater, som udgpr lermassen. Derefter optpes det frosne omrâde 2 ved tilfprsel af varme, som eventuelt udvindes/udtrækkes af grunden i forbindelse med frysning af et næste hosliggende omrâde 2 af grunden 3. Dette kan opnâs ved 10 anvendelse af almindelig kendt varmepumpeteknik og skal ikke omtales nærmere her. Ved optpning af det frosne omrâde 2 vil der opstâ overskudsvand, som ma fjernes, hvilket opnâs pâ den mâde, der er vist i fig. 1d, hvor fryserpret 1 er trukket op, og det derved frem-komne hui er fyldt med sand eller et andet permeabelt materiale. Der 15 er herved dannet et vertikalt dræneringshul i det frosne og derefter opt0ede omrâde 2 i grunden 3. Et tyndt sammenhængende sandlag 5a anbringes oven pâ grunden for at forbinde de 0verste ender af de med sand 5 fyldte dræneringshuller, hvorefter det totale omrâde med dræneringshuller dækkes med en tæt pressenning 6, som ved sine 20 kanter aftætnes/forsegles mod grunden. Der tilvejebringes derefter et undertryk i sandet 5 i dræneringshullerne samt i sandlaget 5a oven pâ grunden 3 ved hjælp af en vakuumpumpe 7, som det er vist i fig.Freezer prene 1 is then added to cooking medium, i.e. any brine, in such a way that an area 2 of the clay soil 3 freezes. By slow freezing, the water in the clay will freeze into ice crystals, which grows by drawing the water out of the non-frozen 1er near / -5 between the ice crystals. The growing ice crystals will exert a consolidating pressure on the mineral grain aggregates that form the clay mass. Then, frozen area 2 is picked up by the application of heat, which is possibly extracted / extracted by the ground in connection with freezing a next adjacent area 2 by the ground 3. This can be achieved by the use of commonly known heat pumping technique and will not be discussed further here. Opening the frozen area 2 will create excess water which must be removed, which is obtained in the manner shown in FIG. 1d, wherein freezer fun 1 is drawn up and the resulting hui is filled with sand or other permeable material. Hereby, a vertical drainage hole is formed in the frozen and then thawed area 2 in the foundation 3. A thin coherent sand layer 5a is placed on top of the ground to connect the upper ends of the drainage holes filled with sand 5, after which the total area with drainage holes is covered. with a dense press tendon 6, which at its 20 edges is sealed / sealed to the ground. Sub-pressure is then provided in the sand 5 in the drainage holes and in the sand layer 5a on top of the foundation 3 by means of a vacuum pump 7, as shown in FIG.

Id, og denne pumpe er i det viste tilfælde koblet tæt til pressennin-gen 6. Denne anbringelse af vakuumpumpen kan naturligvis ske pâ en 25 række forskellige mâder, fx ved, at r0r fra pumpen tæt fpres gennem en gennemfpring i pressenning, eller ved rpr, der via pressennings-kanten fpres ind til forskellige omrâder under pressenningen og eventuelt ned i sandlaget 5a eller sandet 5 i dræneringshullerne. I sâ fald mâ disse r0r, der er sugerpr med sugeâbninger, forsynes med 30 filtre, der tillader dræneringsvand at Ipbe ind i rpret, medens sandet holdes tilbage.Id, and this pump is in the case shown coupled tightly to the press-ness 6. This positioning of the vacuum pump can, of course, be done in a variety of ways, for example, by piping from the pump tightly through a penetration in a press-cut, or by rpr which is pressed into various areas during the pressing operation via the press-cutting edge and optionally into the sand layer 5a or the sand 5 in the drainage holes. In this case, these suction-pipe pipes must be fitted with 30 filters that allow drainage water to penetrate into the drain while retaining the sand.

Overskudsvandet vil derved pâ grund af det frembragte undertryk blive trukket ud af det frosne/opt0ede omrâde 2 i lergrunden 3 og blive pumpet bort. Denne frembringelse af undertryk samt bortpump-35 ningen af overskudsvand kan naturligvis ske ved hjælp af to sæt pumper, nemlig en vakuumpumpe til frembringelse af undertryk samt en sugepumpe til bortpumpning af overskudsvandet.The excess water will thereby be withdrawn from the frozen / thawed area 2 of the clay soil 3 due to the negative pressure generated and pumped away. This generating of negative pressure and the pumping of excess water can, of course, be effected by means of two sets of pumps, namely a vacuum pump for generating negative pressure and a suction pump for pumping away the excess water.

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Efter at den ovennævnte behandiing af omrâder 2 i grunden 3 er gennemf0rt ved hjælp af fremgangsmâden ifplge opfindelsen, vil det totalt behandlede ornride 2 af grunden 3 fremtræde som en forsænk-ning, og hele det grundvolumen 2, der har været frosset og derefter 5 optpet, vil hâve fâet en st0rre tæthed, en st0rre styrke og en st0rre bæreevne samt vasre mindre sætnings0mfïndtfig, end det oprindeligt var. De geotekniske egenskaber for det behandlede grundvolumen 2 vil sâledes være blevet forbedret.After the above-mentioned treatment of areas 2 of the foundation 3 has been carried out by the method according to the invention, the total treated root 2 of the foundation 3 will appear as a recess and the whole of the basic volume 2 which has been frozen and then 5 , will have a higher density, a greater strength and a greater carrying capacity, and a much smaller sentence feel than it originally was. The geotechnical properties of the treated base volume 2 will thus have been improved.

Claims

A method of stabilizing soils, for example fine-grained soil elves, by eliciting settlements in the soil by vacuum pumping comprising generating vertical drainage holes coupled to suction pumps for drainage of drainage water and providing vacuum in an area of the soil which is covered by an airtight pressure sealing which at its edges is sealed to the ground, thereby contributing to the atmospheric pressure of said sentences, characterized in that 1) the ground is first frozen to form ice crystals which grow by drawing water out of the soil / clay between the ice crystals, thereby exerting a consolidating pressure on the mineral-grain aggregates of the soil, 2. the frozen area is again absorbed by application of heat, and 3) excess water is withdrawn from the soil and the drainage holes by means of the vacuum pump for developing said sentences whereby the area will appear as a recess.

Method according to claim 1, characterized in that first freezer pr (1) is installed in the base (3), which is connected to a coal plant for freezing an area (2) of the ground (3), after which the freezer prene is supplied with heating medium. for thawing the frozen area (2), after which the freezer bars (1) are replaced with sand (5) and a sand layer is laid on top of the ground (3) to connect the generated sand drainage holes for application of the press strainer (6) and the start of the vacuum pumping .

Method according to claim 1 or 2, characterized in that heat extracted from the ground (3) by freezing an area (2) thereof is utilized to thaw a previously frozen area (2).