Okuqukethwe kwengcweti yengobo yomlando: umbhalo namafomula askeniwe kugcina i-akhawunti yetiyori yomlando, kodwa akulona ucwaningo lwe-geotechnical, iphrojekthi yodonga olugcinayo, ukubala kokuzinza, ukuhlolwa kodonga olukhona, icebo lokumba noma imiyalelo yokwenziwa. Izingcindezi zomhlaba namanzi zincike enhlabathini ethile, ukuhlukaniswa, ukuminyana, ukugeleza kwamanzi, amanzi angaphansi komhlaba, i-geometry, ukunyakaza kodonga, imithwalo eyengeziwe, isithwathwa kanye nesenzo sokuzamazama komhlaba. Esimeni ngasinye sangempela, umsebenzi wophenyo, idatha yaselabhorethri, amazinga avumelekile kanye nokuhlolwa okuhlanganyelwe kukanjiniyela ogunyaziwe we-geotechnical kanye nesakhiwo kuyadingeka.
Namuhla, i-Savo Kusić igxile emafasiteleni okhuni, amafasitela okhuni-aluminium, amafasitela ngokwezifiso, umnyango kanye nezicelo zekhotheshini. Lesi sihloko sihlala siyingobo yomlando futhi asimeleli ukunikezwa kwedizayini ye-geotechnical, ukubala noma ukwakhiwa kwezindonga ezibambayo.
Ingcindezi yomhlaba ezindongeni ezigcinayo
Isisindo somhlaba esisekelwe udonga olubambayo senza ingcindezi kuso, ivame ukuliphusha ngokuhumushela phambili (fig. 1a) noma liphushe (fig. 1b). Ubukhulu bomfutho womhlaba E buncike ezicini eziningana, phakathi kwazo izici ezibaluleke kakhulu ezibonakalayo zomhlabathi, ukuwohloka kodonga, umswakama wenhlabathi nesimo samanzi angaphansi komhlaba, ukuphakama kodonga, umthwalo wangaphandle kanye nobulukhuni bendawo yangaphakathi yodonga.
Isithombe1- ukunyakaza kokuhumusha nokujikeleza kodonga olusekelayo.
Ingcindezi yomhlaba ekuphumuleni
Uma udonga olubambayo luqinile futhi lunganyakazi, ingcindezi esebenza kulo ibizwa ngokuthi ingcindezi yomhlaba ekuphumuleni futhi ichazwa ngokuthi E.0. Lona kanye ukucindezela okukhona enhlabathini engaphazanyiswa ekujuleni okubhekiwe, ngaphansi kwethonya lesisindo senhlabathi kanye nokulayishwa kuqala kwezingqimba ezigugulekile. Ukucindezela komhlaba ekuphumuleni kuyivelakancane futhi kwenzeka kuphela ezimweni ezithile, njengokugcina izindonga ezisekelwe edwaleni eliqinile, bese kuba namaphrofayili avaliwe emigudu namapayipi, kanye namadokodo amakhulu, anganyakazi ngokuphelele (Fig.2).
Isithombe2- ukuphumula ukucindezela komhlaba esikhumulweni semikhumbi esikhulu.
Ukucindezela komhlaba okusebenzayo
Uma udonga olusekelayo ngaphansi kwesenzo sokucindezela E luya phambili noma luzungeza indawo yonyawo A, noma iphuzu elithile eliphansi, okuyizimo ezivamile emhlabathini ocindezelayo, ngaphandle kwalezi zakhiwo ezivaliwe nezinkulu okukhulunywe ngazo ngenhla, khona-ke isisindo somhlaba esingemuva kodonga siyakhula. Uma ukunyakaza kodonga kukhulu ngokwanele, ingxenye yenhlabathi engemuva kodonga, i-prism ABCA, iyaphulwa bese islayida phansi endaweni eshelelayo AC (fig.2). Ukucindezela okwenziwa iprism eslayidayo odongeni olubambayo kubizwa ngokuthi ukucindezela komhlaba okusebenzayo futhi kuchazwa ngokuthi Ea. Le ngcindezi iphansi kakhulu kunengcindezi ekuphumuleni, cishe0,5ku0,7_E0_. Ngenxa yokushelela kwe-earth prism ABCA, ukucindezelwa kwe-shear τ kwenziwa kusebenze eduze kwendawo eslayidi eyakhelweyo AC, ephikisana nokuslayida futhi yehlise ukucindezela komhlaba. Okwamanje lapho iprism ABCA iqala ukushelela, i-shear igcizelela τ ifinyelela inani layo eliphakeme kakhulu, okusho ukuthi ngaleso sikhathi inani lokucindezela komhlaba okusebenzayo E lincane kakhulu. Ngakho-ke, i-Ea inani eliphansi lomkhawulo lokucindezela komhlaba.
Ukuhlolwa kuka-Terzaghi kokucindezela komhlaba ngezinto zesihlabathi odongeni lobude h=1,50 mibonise ukuthi ukuze kufinyelelwe inani eliphansi lomkhawulo lokucindezela komhlaba okusebenzayo Ea, ukugudluka okumaphakathi kodonga Δl lwe5/10.000ukuphakama kodonga noma ukuzungezisa phezulu kodonga Δl kwe1/5.000_h_ emlenzeni A.
Ingcindezi yomhlaba engenzi lutho
Uma sisebenzisa ukucindezela odongeni ukusuka ngaphandle ukuya ngaphakathi kwenhlabathi (isib.3), udonga luzohlehla futhi umhlabathi uzobumbana. Uma ukunyakaza kodonga kufinyelela kunani elithile Δl, i-prism yobumba ABCA izohlukana nomhlabathi, ezodudulwa phezulu indawo eslayidayo AC ngaphansi kwesenzo esiqhubekayo samandla angaphandle. Ukumelana okuhlinzekwa yinhlabathi ngokumelene nesenzo samandla angaphandle ngesikhathi sokuhlukaniswa kweprism ABCA ingcindezi yomhlaba engenzi lutho Ep. Inani eliphakeme kakhulu lomkhawulo elingafinyelelwa umfutho womhlaba.
Umfutho womhlaba lapho uphumule unqunywa ngokuhlola, kuyilapho ukucindezela komhlaba okusebenzayo nokunyakazayo kunganqunywa ngokwezibalo, kusetshenziswa izindlela zokuhlaziya noma zegraphical, ngokusekelwe olwazini lwezimpawu ezibonakalayo zomhlabathi, ngokuvamile ezinqunywa izindlela zaselabhorethri.
Isithombe3- ingcindezi yomhlaba engenzi lutho kanye neprism eshelelayo.
Okubalulekile ekusebenziseni: izimo ezisebenzayo, zokwenziwa, nezingenzi lutho azikhethwa ngegama lokwakha kuphela. Ukunyakaza okuvunyelwe kodonga, ukucindezeleka okuphumelelayo, izimo ezimanzi noma ezingakhiqiziwe, izinga lamanzi angaphansi komhlaba kanye noshintsho, imithwalo eyengeziwe kanye namandla okulahleka kwenhlabathi phambi kodonga kufanele kuboniswe. Ukukhetha okungalungile kwezimo zokucindezela kungaphazamisa ukuzinza kokushelela, ukugumbuqela, ukuthwala umthamo wenhlabathi namandla odonga.
Ukunqunywa kwe-coefficient yokucindezela kokuphumula K0
Esimeni lapho udonga olusekelayo luvezwa umphumela wengcindezi emile, ingcindezi emile E kufanele yamukelwe ukuze kunwetshwe udonga olusekelayo.0, okukhulu kunokucindezela komhlaba okusebenzayo. Ubukhulu bawo buphakathi komfutho womhlaba osebenzayo kanye nowenziwayo, kuye ngohlobo lwenhlabathi nokucinana kwawo.
Ekujuleni t ngaphansi kwendawo engaphansi, ukucindezela okuqondile okuvela esisindweni senhlabathi uqobo kungu-σt = γ·t. Uma kungenathuba lokunwetshwa okuhlangene kwenhlabathi, ukucindezela okuvundlile σh = γ·t·K0, lapho K0 = σh/σt.
K0 ingcindezi yokuphumula. I-coefficient yokucindezela kokuphumula inganqunywa ukuhlolwa kwe-triaxial ngale ndlela elandelayo.
Isampula lenhlabathi engaphazamiseki ethathwe ekujuleni kwengcindezi yokuphumula ifakwa ku-triaxial apparatus, lapho ingcindezi ebheke eceleni σ3 lapho kusetshenziswa umthwalo oqondile σ1 ilungiswa ukuze ukuguqulwa kwezinhlangothi kungenzeki, okungukuthi isampula elilingana noziro ukuwohloka. Amanani ama-voltage asebenzayo σ’1 kanye no-σ’3 asetshenziswa kumdwebo σ’1 – σ’3 (fig. 4), kanye nengxenye yomugqa oqondile otholwe kumdwebo we-tange inquma inani K0 = σ’3/σ’1.
Figure 4 — ukunqunywa kwe-coefficient K__0 yengcindezi yokuphumula ngokuhlolwa kwe-triaxial.
Ngokuka-Petermann, amanani alinganiselwe e-coefficient yokuphumula angu-
esihlabathini esihlanganisiwe K0 = 0,40 – 0,45
esihlabathini esixegayo K0 = 0,45 – 0,50
kobumba K0 = 0,60 – 0,75
Amanani aselabhorethri: Ububanzi obulinganiselwe obungezansi buhlala buyingxenye yombhalo wokuqala, kodwa azithatheli indawo yokuhlolwa kwesampula elimele, imodeli yokwakheka komhlaba kanye namanani omklamo. Isaziso se-OCR samafomula, okubhaliselwe kanye nama-aphostrophe kufanele kuhlolwe kuqhathaniswa nomthombo ogunyaziwe ngaphambi kwanoma yisiphi isibalo.
Izindlela zokunquma ingcindezi yomhlaba esebenzayo — Ithiyori kaCoulomb
UCoulomb waqala ukushicilela inkolelo-mbono yokucindezela komhlaba (1770. unyaka), ngokusekelwe kolwazi lwasensimini. Wabheka odongeni olubambekayo olusekela inhlabathi exegayo. Ngesinye isikhathi wasusa udonga, lapho ungqimba lomhlaba lwashelela phansi endaweni eshelelayo engu-AC, lutshekele nge-engeli a enezingqimba (fig.5). Isisindo W seprism yomhlaba eslayidayo ABC, eboshwe indawo yezwe BC, indawo eslayidayo AC kanye nodonga olubambayo AB, sisebenza kanye kanye obondeni olubambayo nasendaweni eshelelayo. Ubukhulu bengcindezi yomhlaba esebenzayo Ea banqunywa i-Coulomb ngaphansi kwalokhu kuqagela okubili okulandelayo:
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ukuthi indawo eshelelayo iyindawo yangempela;
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ukuthi amandla amathathu abambayo: isisindo seprism eshelelayo W, ukumelana kodonga olusekelayo Ea kanye nokumelana nokungqubuzana Q eduze kwendawo eslayidayo AC ihlangana endaweni eyodwa, okusho ukuthi indiza yamandla ivaliwe. Ngokwalokhu kucabangela, esimweni sokulingana komkhawulo isisindo W sikhanselwa kanyekanye ngokumelana nodonga olusekelayo Ea kanye nokumelana nokungqubuzana Q endaweni eshelelayo.
Isithombe5- ukunqunywa kokucindezela komhlaba okusebenzayo ngokombono kaCoulomb.
Imicabango yangaphambili ayihambisani neqiniso. Indawo eshelelayo ayiyona indawo eqondile kodwa egobile. Ukuphambana kwamandla okubamba okuthathu kukhona kuphela esimweni esisodwa, lapho indawo engemuva kodonga ivundlile, indawo yangaphakathi yodonga iqondile futhi isiqondiso samandla Ea sivundlile, kuyilapho singekho kwezinye izimo. Kodwa-ke, naphezu kwalokhu kuchezuka, ukunqunywa komfutho womhlaba osebenzayo kusasekelwe kumbono we-Coulomb, njengoba kufakazeleke ukuthi kungasetshenziswa cishe ezimweni eziningi.
Ukunquma ingcindezi yomhlaba esebenzayo Ea Coulomb ucabange ukuthi ngenxa yomphumela wesisindo somhlaba W kwaba khona ukunyakaza kodonga olusekelayo kanye nokwakheka kweprism ABC yokucindezela komhlaba okusebenzayo. Ukucabanga ukuthi ukumelana kwangaphakathi kwenhlabathi kuqukethe ukungqubuzana kuphela. I-Coulomb ibolisa isisindo W sibe izingxenye ezimbili, enye ibheke kumandla okucindezela komhlaba asebenzayo Ea, enye ibheke komphumela wokumelana nokungqubuzana Q eduze kwendawo eshelelayo (isig.5b). Ngokwenza kanjalo, i-Coulomb iphinde icabange ukuthi ingxenye isebenza nge-engeli yokungqubuzana kwangaphakathi nokuvamile endaweni eshelelayo engu-AC, nokuthi ingxenye Ea isebenza nge-engeli yokuchezuka δ nokuvamile ukuya endaweni engaphakathi yodonga AB. Amandla W anqunywa isiqondiso, ubukhulu, nesiqondiso.
Kundawo ethile eslayidayo nge-engeli α evundlile, amandla W atholakala ebusweni be-ground prism ABC ngobude.1,0 mincike ohlelweni kanye nesisindo senhlabathi esinomthamo γ, W=AΔABC x1,00x γ. Amandla okuthi Ea kanye no-Q aziwa ngendlela. Ngokusekelwe ohlelweni lwamandla (isib.5b) kanye ne-sine theorem esinayo:
Isithombe6- Icala lokuphambana kwamandla okubamba ngesikhathi esisodwa.
Le phethini ilungile kuphela esimweni lapho indawo ivundlile (v=0), indawo engaphakathi yodonga iqondile (θ=0) kanye nesiqondiso samandla Ea evundlile (δ=0) okungukuthi lapho udonga lubushelelezi ngokuphelele (isib.6).
Kuleli cala elikhethekile elibizwa nge-Rankine sine:
Isisindo W kulesi simo singu-W =0.5·γ·h_2/tg_α, lapho γ kuyisisindo somthamo wenhlabathi.
Uma sethula inani langaphambili kwisibalo se-Ea, sithola:
Isibalo esandulele sisho indawo eshelelayo engafanele AC. Nokho, kuyadingeka ukucacisa amandla Ea endaweni ebucayi eslayidayo, okungukuthi leyo lapho ukuslayida okungenzeka kwenzeke kakhulu. Kuzoba indawo enikeza inani eliphakeme kakhulu lokucindezela komhlaba okusebenzayo okuphezulu okungu-Ea.
Ngobude obunikeziwe bodonga H kanye ne-engeli engaguquki eyamukelwayo yokungqubuzana kwangaphakathi ϕ, inani lokucindezela komhlaba elisebenzayo liyahlukahluka nge-engeli yokuthambekela engu-α yendawo eslayidayo iye endaweni evundlile. Inani eliphezulu Ea lizotholakala uma sihlukanisa Ea ngo-α futhi sibeka umehluko olingana noziro:
Ifomula ayisona isibali: izibalo eziskeniwe zingase zibe nama-eksponenti angabonakali, izinkomba, ama-engeli nezimpawu. Azikopishelwa kuphrojekthi ngaphandle kokuqhathaniswa nomthombo onokwethenjelwa wochwepheshe, ukuhlolwa kwamayunithi, ukuqagela okuyimodeli nokulawula okuzimele kwemiphumela. Isibalo kufanele sifake amanzi, ukugeleza kwamanzi, imithwalo eduze komqhele wodonga, isenzo sokuzamazama komhlaba nawo wonke amakesi omkhawulo afanelekile.
Ukunqunywa kwama-engeli ϕ kanye δ
I-engeli yokungqubuzana kwangaphakathi ϕ inqunywa elabhorethri. Ubukhulu bayo buncike ohlotsheni lwenhlabathi, umswakama kanye nokuhlangana. Ezinhlotsheni ezithile zomhlabathi, inani le-engeli ϕ ngokuvamile liba phakathi kwemikhawulo enikezwe kuthebula 1.
Ithebula 1 — amanani alinganiselwe we-engeli yangaphakathi yokungqubuzana ϕ ezinhlotsheni ezithile zomhlabathi.
I-engeli yokuchezuka δ yamandla Ea ukusuka kokujwayelekile ukuya endaweni engaphakathi yodonga incike ekushintshashintsheni kodonga kanye nenhlabathi engemuva kwalo kanye nasebunzimeni bendawo engaphakathi yodonga. Uma ukuhlaliswa kwephansi kukukhulu kunokuhlaliswa kodonga, okuyisimo esivame kakhulu, khona-ke i-engeli δ iphozithivu, ukungqubuzana phakathi kodonga nomhlabathi kuhambela phezulu. Uma ukuhlaliswa kodonga kukukhulu kunokuhlaliswa phansi, okuyisimo esikhethekile, khona-ke i-engeli δ iyinegethivu, ukungqubuzana phakathi kodonga nomhlabathi okusebenza phansi. Amanani akhawulayo we-engeli δ awodonga olubushelelezi ngokuphelele δ=0, endaweni elukhuni ngokuphelele δ=ϕ. Ngokuvamile, δ=2/3_ϕ_ yamukelwa, neqiniso lokuthi inhlabathi yodonga ivikelwe unomphela ekumanziseni okuqinile. Uma inhlabathi engemuva kodonga ibhekene nokuzamazama komhlaba okunamandla, δ=ϕ/2 iyamukelwa, futhi uma imanzi kakhulu δ=0.
Amanani edizayini ama-engeli: amanani ethebula nencazelo ϕ kanye ne-δ awasetshenziswanga ngokuqondile endaweni ethile. Ukukhethwa kwamapharamitha kufanele kuhambisane nohlobo nesimo senhlabathi, indlela yokufaka nokuminyanisa, ukugeleza kwamanzi, ukunyakaza okulindelekile kodonga, ubulukhuni bokuthintwa kanye nendlela efanele yephrojekthi.
Ukusatshalaliswa komfutho womhlaba ngemuva kodonga futhi kuphoqelele indawo yokuhlasela Ea
Figure 7 — ukusatshalaliswa kokucindezela komhlaba ngesikhathi sokuzungezisa udonga olubambayo endaweni yonyawo A.
Ukusabalaliswa kokucindezela komhlaba endaweni engaphakathi yodonga kuncike ekuguquguqukeni kodonga olubambayo, ekumeni kwenhlabathi engemuva kodonga kanye nokuma kwendawo yangaphakathi yodonga.
Iphuzu lokuhlasela lokucindezela komhlaba okusebenzayo I-Ea incike ekusabalaleni kwengcindezi endaweni engaphakathi yodonga kanye nokuma kwayo. Ihlala iphakeme phakathi nendawo ye-gravity ebusweni bomdwebo wokucindezela.
I-Coulomb yamukele ukuthi ingcindezi yomhlaba ngemuva kodonga ikhuphuka ngokuhambisana nokujula, njengamanzi, lokho okubizwa. ukusatshalaliswa kwe-hydrostatic yokucindezela komhlaba (fig. 7). Nokho, ukusabalalisa kwengcindezi ye-hydrostatic kuba khona kuphela esimweni lapho udonga luzungeza umlenze A noma endaweni ethile engezansi, kuyilapho kuzo zonke ezinye izimo luchezuka kulo.
Uma udonga olubambayo luzungeza indawo yonyawo A, noma indawo ethile engezansi, inhlabathi iya phansi (fig. 7a), kuyilapho kungekho ukusunduza ukuya maphakathi nenhlabathi. Kulesi simo, ukushelela kwenhlabathi kubonakala ezindaweni zokumelana okuncane M1C1, M2C2… ngokuhambisana nendawo eslayidayo AC, okwenzeka lapho ukuzungezisa kodonga kunkulu ngokwanele ukwenza i-priding ABCA.
Ngakho-ke, kulesi simo, ingcindezi ikhuphuka ngokulinganayo nokujula, okungukuthi ukusatshalaliswa kwengcindezi yomhlaba ngokuya nge-Coulomb hydrostatic. Umdwebo wokucindezela komhlaba osebenzayo uzotholakala ngokusekelwe olwazini lwamandla Ea nokuphakama kodonga h, njengoba amandla Ea alingana nendawo yomdwebo wengcindezi abc (Fig.7b):
Ea=x·h/2, isuka x=2Yebo/h,
okungukuthi, kusukela Ea = ½ γh2Ka, x = γhKa.
Isithombe8- ukusatshalaliswa komfutho womhlaba lapho udonga luzungeza phezulu B noma endaweni ethile ephakeme L.
Uma udonga olusekelayo lujikela phezulu odongeni B noma indawo ephakeme L (fig.8a), kukhona ukusunduza engxenyeni engenhla kuya ngaphakathi kwenhlabathi, okuthi ngenxa yalokho iphushelwe phezulu endaweni ekwazi ukumelana kancane M1C1, M2C2____…
Ekuphendukeni okukhulu ngokwanele kodonga, indawo eslayidayo AC iyakhiwa, lapho i-prism eslayidayo islayida phansi phakathi ne-extrusion. Ngenxa yokuphusha kwenhlabathi engxenyeni engenhla, kuvela umfutho womhlaba onganyakazi, ophakeme kakhulu kunowosebenzayo, futhi kuleyo ngxenye umdwebo wokucindezela bd uhambisana nokucindezela kwe-passive Ep (fig. 8b). Njengoba ingqikithi yokucindezela komhlaba i-E incike kusayizi we-prism yomhlaba ABCA futhi ilingana nendawo engunxantathu yomdwebo wokucindezela abe, lo mdwebo uzokwehla ekuhambeni kwawo okuqhubekayo, kuze kube yilapho ubuso bawo bulingana nendawo engunxantathu abe. Umdwebo wangempela wengcindezi kuleli cala uthi curvilinear bc, ongakwazi ukunqunywa ngokwezibalo. Kodwa-ke, indawo emaphakathi ye-gravity S yobuso bomdwebo ac ingaphezulu kwesikhungo sokudonsela phansi kobuso bomdwebo ongunxantathu, ongathandeki kakhulu ekuzinzeni kodonga olubambayo, ngoba indawo yokuhlasela yamandla Ea iphakeme. Ngokusho kwe-Terzaghi, itholakala kuhhafu wobude bodonga olusekelayo.
Uma udonga olusekelayo luyiswa phambili ekuhumusheni (fig. 9a), ingcindezi ngaphambi kokunyakaza ehambisana nokucindezela komhlaba esimweni sokuphumula E0 yehla, lapho izindawo zokumelana okuphansi zingaveli, kodwa uma udonga luhamba lube lukhulu ngokwanele, kudalwa indawo e-AC_A eshelelayo engu-BC_A ishelela phansi. Njengoba ingcindezi ephelele ilingana nendawo engunxantathu yomdwebo wokucindezela abe (fig. 9b), umdwebo wokucindezela uzokwehla ekuhambeni kwawo okuqhubekayo. Umdwebo wangempela wokucindezela umugqa ogobile ac, ongenakunqunywa ngokwezibalo. Ngokusho kwe-Terzaghi, isikhungo samandla adonsela phansi S siphezulu 0,40 – 0,45_h_.
Figure 9 — ukusabalaliswa kwengcindezi yomhlaba ngesikhathi sokunyakaza kokuhumusha kodonga olubambayo ukuya phambili.
Uma kucatshangelwa indlela yokunquma ukucindezela komhlaba njengenani elidlulele, elikhulu kunawo wonke elisebenzayo kanye nelincane kakhulu lokunganyakazi, ithiyori kaCoulomb ibhekwa njengendlela eyeqisayo yokunquma ukucindezela komhlaba.
Inothi lokugcina lobunjiniyela: indawo yengcindezi yokusabalalisa neyokuhlasela incike endleleni okuyiyonayona egogeke ngayo isakhiwo. Ngaphezu kokucindezela komhlaba, umfutho we-drainage kanye ne-hydrostatic pressure, ukuzinza komhlaba wonke nangaphakathi, ukushelela, ukufuduka, ukuthwala umhlabathi nokuhlala, amandla odonga nesisekelo, ukuguguleka, ukucwiliswa, izigaba zokumba kanye nokuzinza kwesikhashana kufanele kubhekwe. Isimo sodonga olukhona olubonisa ukunyakaza, ukuqhekeka, ukuvuza noma ukuvuza kwamanzi okungalawuleki kudinga ukuhlolwa kochwepheshe ngokushesha.