Hidrológiai Közlöny 1983 (63. évfolyam)

4. szám - Dr. Kovács György–Ujfaludi László: Finom szemcsék mozgása kutak környezetében

Dr. Kovács Gy.—Újlaki L.: Finom szemcsék mozgása Hidrológiai Közlöny 1983. 4. sz. 153 (1,5—2,0 )Dt-zd„~zDu (11) ahol Dk a KÉZDI—KOVÁCS módszer alapján két részre osztott talaj kitöltő frakciójának legnagyobb szemcsemérete, D»5 a teljes talajminta 85 súlyszázalékához tartozó átmérő. Ha a két egyenlőtlenség egyidejűleg nem teljesíthető, mindig a jobb oldalt kell mértékadónak tekinteni. IRODALOM [1] ABRAMOV, C. K. (1952): Metodi podbora i raszcsota filtr v burovih szkvazsin, Moszkva, 1952. [2] C

ISTIN, J. (1965): K problematic© nékatrerieh mechaniczkych filtracnioh deformaci nesondrenvek zemin v zemni.ch hrázic, V odohospodarski/ Casopis, 1965. 2. [:i] KÉZDI A. (1969): Árvédelmi létesítmények védőképességének fokozása, I. sz. jelentós, Budapesti Műszaki Egyetem, Geotechnikai Tanszék, 1969 (kézirat,), Budapest. [4] KOVÁCS, Oy. (1971): A szivárgó vízmozgás hatása szemcsés rétegek állékonyságára, Vízügyi Közlemények, 1971. 4. [5] KOVÁCS, Gy. (1972): A szivárgás hidraulikája. Akadémiai Kiadó, Budapest, 1972. [6] LUBOCSKOV, E. A. (1962): Neszuffozionnije neszvjazinüje grimtii, Izvesztiyja VNIGG, 1962. 71. [7] SCHMIEDER, A. (1966): A kutak környezetében megengedhető sebesség problémájáról, Hidrológiai Közlöny 1966. 10. [8] SICHÄRDT, W. (1928): Das Fassungsvermügen von Hohrbrunnen, Berlin, 1928. 0 JIBHH(CHHH MeJIbKHX 3epeH 0CaA04HbIX nopoA B HENOCPEACTBEHHOIÍ 30He BAHAHHA CKBA HH d-p Koecm, JJ. 'ineii-Kopp. An BHP—yücfiaAydu, Jl. B xrifle HccjieflOBaHHií aBTopu BbinojiHHJiH MHoroMHCJlCHHbie 3KCnepiIMeHTbI C IJCJIbK) H3yTCHHfl npoueccoB cy(t)([)03jin rpyHTOB. B pe3yjibTaTe STHX 3KcnepHMeHT0B y;iajiocb Rojiee ACTajibHo pacKpwTb oTAejibHbie AeTajni npouecca BHyTpeHHeö cy(}>(|)03Hn. 0Ka3biBaeTCH nponecc riponcxoAHT no cJieAyroiucMy: IIOA BJIHHHNEM Heßojibiuiix CKOPOCTEÜ n0T0Ka MSCTHHKH rpyHTa ocraiOTCfl HenoAßioKHbiMii H ABn>KeHHe npucxoAHT corjiacHO 3ai<0Hy /JAPCM. Ilpii AOCTIDKCHHH noporoBon CKOpOCTH (v"lcr) MaCTHLlbl MejlbKHX (JipaKLJHH CABHHYTCFL H HANNHAIOT AAFIHBATB IIO/IOCTH Me>KAY LACNMAMH Cojiee KpynHbix (j)pai<UHH— conpoTHBJieHHe fíjioKa rpyHTa BO3pacTaeT. Eme Gojibine yBejiimuBaji CKOpocTb noTOica HaCTynaeT BTopoií nopor (vtr'), KORAA B rpyHTe oöpaayiOTOi MHKpOCKOníJMCCKHe TpyfiOMKH, Mepe3 KOTOpbie MeJIbKHe 3CpHa yAajijiioTcji 113 riopoAbi. ECJIH pa3iwepbi OTBepcTHii (|)HjibTpa A0CT3T0MH0 BejiHKH, TO ripii napajie/ibHoivi HanpaBjieHHii noTKa BCH MEJIBKAJI (})paKnHji MO>KCT BMÍÍTH I!3 nnpoAbi. ripn paAwajibHOM nanpaBJieHiiH nmoKa noTepa MejibKOií (})pai<nHn He HacTynaeT aawe npn CKOpOCTÍIX 10—15 Vier- B T3KHX CJiyHaflX 3epHa, BbIMHTbie B03Ae (})HAbTpa SaMemaiOTCÍI APyrUMH, ABIiraKHUHMIICfl na rpacKTopmix c OnjibiiiHMH pa«HycaMH. BCJICACTBHC KOHBCpreHUHH J1HHHÜ TOKa MaCTHMKH CF)HBaK)TC5I H npeiuiTCTByiOT npoAOJDKCHUK) cMbiüa. BcACACTBiie yKa3anHorn oíicTOjiTejibCTBa conpoTHBJieHHe RjioKa rpyHTa B Komié 3KCNEPHMCHTA HeiiaMnoro OTAIMAETOI OT CBOCPO nepBoiiaMajiboro 3HaMennfi. Ba>Kne inline npaKTHMecKiie BblBOAbl CACAyK)IUH: 1. MoAejib KE3J1H-K0BA

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r, npn KOTopoii oOpasyioTCji TpaHcnopTiibie MHKpoTpy6oHKH MO>KCT ObiTb onpeAeJieHa (J)opMyjroií (9). MaKcmwajibiio AonycTHMyio CKOpOCTb B03Jie (JiHjibTpa npii paAHajibHOM HanpaBjreHHH ABIDKeHHÍI nOTOKa MO>KHO OnpeAeJTHTb 3MnnpHHecKoií (j)op,Myjioii (10). 3. reoMeTpnqecKoe ycJioBiie BHeuiHCH cy(|)i|)03nn, T. e. pa3Mep OTBepcTHii AAji rio^'iHpaioinero <J)HAbTpa pacniTbiBaeTCíi no ())-Ae (II). Movement of fine fractions in the vieinty of wells (Guidelines for designing well screens and development pumping) Dr. Kovácsi Gy. Corr. M. Acad. Sei. Hung.

— Ujfaludi L. The research project included a large number of experiment to study the process of soil suffosion. As a result thereof more detailed information could be gained on particulars of internal suffosion. The procesR takes thus the following course

: Low seepage velocities fail to displace the soil particles and flow occurs in accordance with Darcy's law. Once the limit seepage velocity v\cr is attained, the fine fractions start moving and block some of the interstices between the coarser particles increasing the resistance of the soil block. As the velocity of flow is increased further, a second limit vcr' is observed, at which small (micro) ducts are developed in the soil, through which fine fractions are removed from the layer. If the mesh size of the screen is sufficiently large, then in the case of parallel flow the entire fine fraction may be removed at this velocity. However, in the case of radial flow the fines are not removed even at velocities 10 to 15 times as high as v

Cr'

• In this case the fines removed from the vicinity of the screen are replaced by other ones from more distant [joints along the radius, which are congested on account of the narrowing character of the flow bands and block the path of further soil scouring. Therefore, the resistance of the soil mass at the end of the process does not differ much from the initial value. The practical conclusions of major importance are as follows: 1. The KÉZDI-KOVACS approach concerning the geometrical condition of internal suffosion (viz. resolution of the soil into a self-supporting skeleton and a filling fraction) was substantiated. 2. As regards the hydraulic criteria of internal suffosion it was found possible to define s veral critical velocities. The velocity v"

c

r at which the fine particles are set into movement can be found from Eq. (8). The velocity Vcr at which the micro ducts are developed is given by Eq. (9). The highest allowable flow velocity in the vicinity of well screens (radial flow) is obtained from the empirical formula of Eq. (10). 3. The geometric condition of external suffosion, i. e. the mesh size of the supporting screen for a particular soil is calculated from the empirical relationship described by Eq. (11).