I-capillarity kunye nokungavimbi komhlaba

I-capillarity

Ukuvela kwe-capillarity

Ukuba ityhubhu yeglasi emxinwa siyifaka kwisingxobo esinamanzi azolileyo angenamsinga, amanzi kwityhubhu aya kunyuka aye kubude hk ngaphezu komgangatho N esingxobeni, yaye umphezulu wamanzi kwityhubhu uza kubumba i-meniscus m (umz. 1_a_). Okukhona ityhubhu imxinwa, kokukhona ubude bokunyuka kwamanzi nge-capillary hk bubukhulu.

Ukuphakama kwamanzi kwiikhapilari kubangelwa ngamandla anyusela i-meniscus m, kwaye kuchazwa ngamandla okutsalana phakathi kweemolekyuli zamanzi kunye neglasi kunye noxinzelelo lomphezulu phakathi kweendonga zetyhubhu emxinwa kunye nomphezulu wamanzi.

Kwindawo yokudibana phakathi kodonga lwetyhubhu yeglasi nomphezulu wamanzi usebenza amandla e-capillary R kwicala le-tangent kumphezulu we-meniscus m, abonakaliswa ngumlinganiselo wobunzima ngeyunithi yobude, kwi-p/cm. Ngokwahlula amandla R abe licandelo J elihambelana nomphezulu wodonga kunye necandelo P elingqamene nodonga, sifumana amandla okunyusa e-meniscus (sl. 1_a_): J = R cosα.

I-engile α enziwa ngamandla R kunye nomphezulu wodonga ibizwa ngokuthi yi-engile yekapilarithi yaye ixabiso layo lisukela ku 0 ukuya ku 90O. Ukuba amanzi kumbhobho wekapilari kunye neendonga zawo zicocekile ngokupheleleyo, ngoko α=0, umphezulu we-meniscus ngowesangqa sesiqingatha, amandla okunyusa J = R aphezulu kakhulu (sl. 1_b_). Ukuba amanzi aqulethe amafutha okanye iiasidi eziphilayo okanye ukuba iindonga zinamafutha, ngoko α = 90°, akukho kubunjwa kwe-meniscus, yaye akukho kunyuka kwamanzi ngekapilari.

Umz. 1. Ukunyuka kwamanzi nge-capillary kunye nesenzo samandla e-capillary

Amandla okunyusa J = R cos α sifumana kwiimeko ze-equilibrium, ngokwazo amandla okunyusa ewonke J kulo lonke ujikelezo lwe-meniscus, oko kukuthi, ityhubhu ye-capillary enobubanzi r, agcina ikholamu yamanzi kwityhubhu enobude h__ₖ:

R cos α · 2π_r_ = π_r_² h__ₖ γ__w

apho γ__w ubunzima bomthamo wamanzi.

Kusuka kwibala elingaphambili sifumana amandla e-capillary anyukayo:

R cos α = (r · h__ₖ · γ__w) / 2

oko kukuthi ukuphakama kokunyuka kwecapillary:

h__ₖ = (2_R_) / (r · γ__w) · cos α  [cm].

Amanzi ashushu e-capillary anyuka kumbhobho we-capillary afikelele kubude obuphezulu kunamanzi abandayo ngenxa ye-viscosity ephezulu. Ngenxa yoko, kubude obufanayo bokunyuka kwe-capillary h__ₖ amandla R cos α abe mancinci kumanzi ashushu e-capillary kunakumanzï abandayo. Ngokweemvavanyo ezenziweyo kumaqondo obushushu ahlukeneyo amanzi t phantsi kweemeko ezifanayo ngokupheleleyo, afunyenwe amaxabiso alandelayo omkhosi wokunyusa R cos α:

Amanzi kwityhubhu yecapillary akwinzame yokutsalwa, kuba amandla R cos α awanyusa phezulu, logama amandla omxhuzulane ewatsalela ezantsi. Noko ke iindonga zetyhubhu yecapillary zikwinzame yoxinzelelo phantsi kwempembelelo yamandla e-capillary R.

I-capillarity emhlabeni

I-capillarity ikhona nasehlabathini, apho imibhobho ye-capillary yenza ii-pores, ezinxibelelene omnye nomnye kuzo zonke iindlela. Ukuba umhlaba ucolekile ngakumbi, i-pores nazo ziba zincinci ngakumbi yaye ukuphakama kwe-capillary kokunyuka kuba kukhulu. Obu bubude buxhomekeke nakwisakhiwo somhlaba. Noko ke, ii-pores emhlabeni zinokuba nobukhulu obahlukeneyo yaye kulo meko nobude bokunyuka kwe-capillary buyahluka. Ukuba amanzi e-capillary, xa enyuka, efikelela kwi “ndawo ezibanzi”, oko kukuthi ukuya kwipore enkulu kunaleyo ifanelekileyo kumandla anyukayo obubanzi bepore emxinwa kubude obufikelelweyo, ngoko ke ukunyuka kwe-capillary ngakumbi kuxhomekeka kubukhulu baloo pore inkulu. Kule meko sinobude bokunyuka kwe-capillary olusebenzayo h__ₖₐ oluxhomekeke kwii-pores ezinkulu. Ngokwahlukileyo, xa ekwehleni kwenqanaba lamanzi aphantsi komhlaba amanzi e-capillary, ehla ukusuka phezulu esiya ezantsi, edibana ne “ndawo ezimxinwa”, aya kuhlala kuloo nzulu yaye akasayi kuqhubeka ehla. Kulo meko sinobude bokunyuka kwe-capillary obungasebenziyo h__ₖₚ, obuxhomekeke kwii-pores ezincinane.

Ngokwemingxuma nobume bomhlaba kuhlukaniswa amanzi e-capillary avaliwe kunye navuliweyo.

Amanzi e-capillary avaliwe anxulumene nesipili samanzi angaphantsi komhlaba yaye xa enyuka atyhala umoya ophambi kwawo aye kummandla ophezulu womhlaba. Ngenxa yoko inani lomoya kummandla ophezulu liyanda, yaye ngaloo ndlela noxinzelelo lomoya, kwiipore zaloo ndawo. Olu xinzelelo lomoya luyalwa nokunyuka kwe-capillary, yaye ukuphakama kokunyuka kwe-capillary kuba kuncinci. Le meko yenzeka kwiingqimba ezisezantsi zomhlaba, ngoko nangoko ngaphezulu kwenqanaba lamanzi angaphantsi komhlaba, apho iipore zincinci yaye xa kunyuka kwe-capillary amanzi azalisa ngokupheleleyo zonke iipore.

Amanzi e-capillary avulekileyo nawo anxulumene nomphezulu wamanzi aphantsi komhlaba, kodwa akufuphi neepore ezizaliswe ngumoya. Le meko yenzeka kwinxalenye ephezulu yomhlaba apho iipore zinobukhulu obahlukeneyo, ukuze amanzi azalise ngokupheleleyo kuphela iipore ezincinane, ngoxa kwiipore ezinkulu ezikufutshane kukho umoya. Ngexesha lokunyuka kwe-capillary, amanzi atyhala umoya aphume kwiipore ezincinane aye kwiipore ezinkulu ezikufuphi, ukuze kummandla ongaphezulu komqolo wamanzi kwi-capillary kungabikho xinzelelo lomoya, yaye amanzi e-capillary avulekileyo anyuke aye kubude obukhulu kunawavalekileyo.

Indawo apho kukho amanzi e-kapilari avaliweyo okanye avulekileyo imiselwa ngokusekelwe kwisixa samanzi w emhlabeni.

Kwamanzi e-capillary avaliweyo onke ama-pores agcwele ngamanzi, nto leyo ethetha ukuba isixa samanzi emhlabeni w = wZ, oko kukuthi iqondo lokuzaliseka S__ᵣ = 1,0.

Kumanzi e-capillary avulekileyo, iipore ezincinane zizaliswe ngokupheleleyo ngamanzi, ngelixa iipore ezinkulu zizaliswa ngokuyinxenye ngamanzi, oko kukuthi yifilimu yamanzi egquma amasuntswana aqinileyo kunye namanzi asezingontlolo (fig. 2) kwiindawo zokunxibelelana phakathi kwamasuntswana aqinileyo, yaye ngokuyinxenye ngumoya, ngoko ke kule meko w < wZ, oko kukuthi S__ᵣ < 1,0.

Iindawo eziphakamileyo zokunyuka kwe-capillary h__ₖ kwiintlobo ezahlukeneyo zomhlaba zimiselwa ngovavanyo lwaselabhoratri. Iindawo eziphakamileyo eziqhelekileyo h__ₖ kwiintlobo ezahlukeneyo zomhlaba zikwaziwe kule mda ulandelayo:

Sl. 2. Ifilimu yamanzi kunye namanzi angaphezulu asekwikona

Emhlabeni amandla e-capillary R asebenza ngoxinzelelo kwiindawo eziqinileyo kangangokuba phakathi kwazo kuvela oko kubizwa ngokuba kukudibana okungathi kuyinyani, okusebenza njengohlobo oluthile lokubopha phakathi kweendawo eziqinileyo. Noko ke, ukudibana okungathi kuyinyani kukhona kuphela lo gama kukho ukunyuka kwamanzi okune-capillary kwimingxuma yomhlaba. Xa umhlaba untywiliselwa emanzini, imingxuma izele ngamanzi yaye ukudibana okungathi kuyinyani kuyayeka ukubakho.

Ukubonakala kwe-adhesion kubhekisa kwinto yokuba isanti entle, ethe kratya xa yomile, ifumana xa imanzi ubunye obuthile bokubopha ukuze ikwazi ukumodelwa, nto leyo engenakwenzeka ngesanti eyomileyo.

Kuyaziwa ukuba isanti (ukuba ayisilo daka okanye uthuli) kwiilwandle zolwandle, xa imanziswe ngamaza, inamandla okuxhasa alungileyo kangangokuba umntu angakhwela ibhayisekile okanye imoto phezu kwayo, ngoxa kancinane kude, apho amaza engafiki khona, loo santi ikwimeko eyomileyo yaye amavili ayatshona kuyo, ukuze uhambo ngaluphi na uhlobo lube lungenakwenzeka.

UKUNGANGENI

Ukuhamba kwamanzi kubunzima obungena manzi

Masijonge izitya ezidibeneyo A, B, C, D, ne E (sl. 3), apho inxalenye enye ukusuka a ukuya b ubude L izaliswe sisixhobo esivumela ukungena, umzekelo isanti. Ukuba kwelinye icala lezitya ezidibeneyo sigalela amanzi ukuya kwinqanaba N₁, ngoko inqanaba lamanzi kwizitya ezidibeneyo liya kwahluka, oko kukuthi, liya kuncipha ngokobude bendlela esele ihanjwe ngamanzi.

Sl. 3. Ukuhamba kwamanzi ngokuqhekeza okungena amanzi

Ngexesha apho ubude bekholamu yamanzi h₁ bufikelelwe phambi kwefilter, emva kwefilter kuya kuba h₂. Umahluko phakathi kwamanqanaba N₁ ne N₂ ngoko ke ngu:

h = h₁ − h₂

Umahluko h umele uxinzelelo lwe-hydrostatic olulahlekileyo, olusetyenziswe ekoyiseni ukuxhathisa kokuhamba kwamanzi ngesihluzi. Le nto yafunyanwa sisazinzulu saseFransi uDarcy kwangowe 1856. Ngelo xesha naye wabeka nalo mzekelo ulandelayo wokubala isantya sokuhamba kwamanzi kwizinto ezivuzayo:

V = k × (dh/dL) = ki

iphi i:

• V = isantya sokuhamba kwamanzi kumsinga ohamba kwi-mass enokudlula, [cm/sec],
• k = ngumlinganiselo wokungena kwamanzi oxhomekeke kwiimpawu zomhlaba [cm/sec],
• dh = ubude obufumaneka xa ubude h bohlulwa bube yinani elikhulu lemaleko emincinci [cm],
• dL = ubude obufunyanwa xa ubude L bohlulwa ngobuninzi obufanayo bobude njengobude h, [cm].

Umlinganiselo dh/dL = i ngumlinganiselo wobude obulahlekileyo ekuhlaleni xa kuzika kuthelekiswa nomgama amanzi ahambileyo, kwaye ubizwa ngokuba kukuwa kwe-hydraulic, i-hydraulic gradient okanye kwakhona ithambeka le-piezometric. Eli gama lokugqibela lisuka kwimibhobho B, C no D, ezibizwa ngokuba ziimibhobho zepiezometer. Lo mzekelo ungaphambili ubizwa ngokuba ngumthetho kaDarcy wokuhamba kwamanzi kwisihluzo.

Ubuninzi bamanzi q, obuthi ngexesha elithile t budlule kwisihluzo esinendawo enqamlezileyo A yile

q = kAti,

ukuba ivela phi

k = q / (Ati),  oko kukuthi k = qL / Ath,

apho i = h / L = ukuhla kwe-hydraulic kubude L (ukuba kuthe tye).

Ikoefisienti k ichaza ukungena komhlaba kubushushu 10°C.

k = V / i  [cm/sec]

Isantya sokuhamba kwamanzi ngomhlaba sifunyanwa kule fomula

V = q / A  [cm/sec],

apho q = isixa samanzi esihamba ngomhlaba nge-cm³ ngesekhondi, kubushushu be-10°C, A = indawo yecandelo lomhlaba apho amanzi edlula khona, [cm²].

Umthetho kaDarcy usebenza kwi iintshukumo zelaminar zamanzi, oko kukuthi iintshukumo ezizolileyo, ezingenamaqhwithi yaye ngezantya ezincinci.

Isantya sefilter V sisantya esiphakathi sokuhamba kwamanzi emhlabeni kwaye asihambelani nesantya sokwenene sokuhamba kwamanzi, esikhulu ngakumbi. Xa amanzi edlula kwifilter, izinto ezilinganayo zokuhla koxinzelelo dh zihlala zisetyenziswa kumgama ongalinganiyo wendlela yamanzi dL, ngoko ke i-hydraulic gradient iyatshintsha ukusuka kwindawo enye yomhlaba iye kwenye.

Ukungena kwamanzi emhlabeni kuxhomekeke kubukhulu bama-pores akhoyo kuwo. Ukuba sibeka umhlaba phantsi komthwalo, ama-pores ayancipha yaye ukungena kwamanzi kuyancipha. Ngoko ke, kuloo mhlaba mnye, umba wokungena kwamanzi k ulingana ngqo nobukhulu bokuqala-porosity, oko kukuthi nomlinganiselo wawo wama-pores e. Noko ke, kwiintlobo ezahlukeneyo zomhlaba, i-porosity ebonakaliswe ngumlinganiselo wama-pores e ayinakuba ngumlinganiselo wokungena kwamanzi, kuba oku kungena kuxhomekeke hayi kangako kwiporosity iyonke yomhlaba, kodwa kubukhulu bama-pores kuwo. Umzekelo ke isanti enamatye amancinci eneporosity e = 0,25, inomlinganiselo omkhulu kakhulu wokungena kwamanzi, k = 2–3 cm/sec, ngelixa udongwe oluthambileyo, oluneporosity ye 60%, umlinganiselo wama-pores e = 1,50, lunokungena kwamanzi okuncinci, k = 10_⁻⁶ ukuya ku 10⁻_¹¹ cm/sec.

I-coefficient yokungena k inokumiselwa ngokubala, ngovavanyo lwaselabhoratri kunye novavanyo lwentsimi.

Ukumiselwa kwekhowefishienti ngeendlela zokubala kusekelwe kubume be-granulometri bomhlaba. Ukumisela ikhowefishienti k kuthathwa umqathango wokuba amasuntswana aqinileyo omhlaba anesimo esingqukuva, nto leyo engahambelani nenyani, ingakumbi kumhlaba odityanisiweyo. Ngenxa yoko, amaxabiso ekhowefishienti k amiselwe ngale ndlela awamkelwa njengachanileyo.

Ukumiselwa kwecoefficient k ngeemvavanyo zaselebhu yeyona ixhaphake kakhulu yaye zenziwa kwiisampuli zomhlaba ezingaphazamisekanga. Nangona kunjalo, ukuchaneka kwe-coefficient k emiswe ngale ndlela kuxhomekeke kwizinto ezininzi ezifana nokuba ngaba isampuli ekwenziwa kuyo uvavanyo imele kangakanani umaleko ovuzayo emhlabeni, emva koko kwimeko yokungaphazamiseki kwesampuli kwisixhobo sovavanyo nakwindlela yokwenziwa kovavanyo. Ngokuhlola inani elaneleyo leesampuli eziya kumela umhlaba othile, ngokuthatha isampuli entsimini kwiisilinda zesixhobo sovavanyo ngokwaso yaye ngendlela efanelekileyo yokwenza uvavanyo, kunokufunyanwa amaxabiso aphantse achaneke e-coefficient k anokusetyenziswa njengawanelisayo.

Ukumiselwa kwe-coefficient k ngovavanyo lwasentsimini kunika amaxabiso achaneke kakhulu, kuba kuhambelana ngokupheleleyo nokwakheka nokubekwa kweenkalo zomhlaba apho lowo mhlaba ukhona khona. Nangona kunjalo, le ndlela yokumisela i-coefficient k ifuna ixesha elininzi neendleko ezinkulu, yiyo loo nto isetyenziswa kunqabile kwaye kuphela kwiimeko apho ixabiso layo elichaneke ngokupheleleyo liyimfuneko.

Ngokwemimiselo yethu yokuseka iziseko, kuthathwa njengomhlaba lowo unomlinganiselo wokusasaza:

• k < 10_⁻_¹¹ cm/sec — phantse ayingadluli
• k < 10_⁻_⁹        — ingangenwa kakhulu ngamanzi
• k < 10_⁻_⁷        — ayivumeli ukungena kakhulu
• k < 10_⁻_⁵        — ingahambi kakuhle phakathi
• k < 10_⁻_³        — ingena lula ngakumbi
• k > 10_⁻_³        — idlula kakhulu