Ingcindezi emihubheni yakhiwa yilokhu (umf. 1):
Sl. 1. Amandla okucindezela asebenza emhubheni
a) yengcindezi eqondile P phezulu, ebizwa ngokuthi ingcindezi yenkulunkulukazi,
b) ukucindezela okuvundlile S, okubizwa ngokuthi ukucindezela kwecala,
c) ukusabela phansi A, okubizwa ngokuthi ingcindezi yasemnyango.
Ubukhulu bengcindezi yomhlaba emhubheni buhamba ngaphakathi kwemikhawulo ebanzi kakhulu. Ekuqaleni, ngesikhathi sokumba umhubhe, ingcindezi yezintaba imncane kakhulu futhi isuka ku 0 iye ku 0,50 kp/cm2, kodwa ngemva kokumba iyakhula futhi isuka ku 0,8 iye ku 12,0 kp/cm2, kuye ngohlobo lomhlabathi nezici zawo zomzimba, ukuphakama kwezendlalelo ezisemva komhubhe kanye nobukhulu bokunyakaza emhlabathini okuvela njengomphumela wengcindezi yezendlalelo ezingenhla. Ngenxa yokuncika ezicini ezahlukene, ukunquma ingcindezi yezintaba emhubheni kuba nzima kakhulu, kangangokuba ngendlela yethiyori akunakutholakala inani eliqondile lengcindezi yomhlaba, kodwa kuphela eliseduze. Ngokumelana kwangaphakathi komhlabathi, kuphikisana nomphumela wengcindezi yomhlaba kuphrofayili yomhubhe. Uma umhlabathi lapho umhubhe wenziwa khona uqukethe idwala eliqinile nelihlangene, ingcindezi kuphrofayili yomhubhe incane, ngoba isisindo sezendlalelo ezisemva komhubhe sithathwa ingcindezi ye-shear yedwala eliqinile. Esimweni esinjalo akudingeki ukwakha ulayini womhubhe noma izisekelo ngesikhathi sokumba umhubhe, ngakho-ke nokunquma ingcindezi yomhlaba kuphrofayili yomhubhe kuyashabalala.
Ezintabeni ezingahlangani nezibhidlika kalula, ingcindezi ngenxa yesisindo sezingqimba eziphezulu kuphrofayili ye-tunela ingadlula amandla alezo zintaba, ngenxa yalokho kuvela ukuwohloka kwenhlabathi kanye nokuguquka okukhulu kuphrofayili ye-tunela. Ezimweni ezinjalo kufanele kwakhiwe isekelo lesikhashana ngesikhathi sokumba i-tunela, bese kulandela ulwelwesi lwe-tunela oluzomelana nengcindezi yezintaba futhi luyidlulisele ngezindonga eziyisisekelo iye ezingeni elingezansi.
Enhlabathini ebophene, ukumelana kwangaphakathi kuqukethe ukubambana nokuhlikihla, kanti enhlabathini engabophene kuqukethe ukuhlikihla kuphela ngaphandle kokubambana. Kodwa-ke, ngenxa yenani eliguqukayo lokubambana ngaphansi komthelela womswakama, kanye nokwendlaleka kwenhlabathi enezakhiwo ezihlukahlukene, ukubambana akucatshangwa njengokumelana kwangaphakathi, ngakho ngisho nasenhlabathini ebophene kubalwa kuphela ukuhlikihla kwangaphakathi. Ngakho-ke kuzo zombili lezi zimo zokugcina kudingeka ulwelwesi lwe-tunela, okusho ukuthi kufanele kunqunywe ingcindezi yenhlabathi ku-tunela.
Ukuze kunqunywe ubukhulu bengcindezi yomhlaba emhubheni kunemibandela elandelayo:
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Umbono wokuthi ingcindezi yomhlaba ikhula ngokulingana nokujula
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Ukuqagela okusekelwe emithethweni yokulingana kwemizimba ewohlokayo
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Ukuqagela kokwakheka kwekhothamo elikhulula umthwalo emhlabathini
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Ukuqagela okususelwa emithethweni yokunwebeka.
Ukucabanga ukuthi ingcindezi ikhula ngokulingana nokujula
Ngokwalesi sicabange, ku-vault yomhubhe (sl. 2) kusebenza ingcindezi ye-arch P ngenxa yesisindo senhlabathi kulo lonke ubude obungaphezu komhubhe kuze kufike phezulu kwendawo, nasebubanzini bomhubhe owembuliwe b. Ngakho-ke, ingcindezi ye-arch ingu
P = γ bt [Mp/m]
lapho γ kuyisisindo somthamo sezingqimba zomhlabathi ngenhla komhubhe [Mp/m3], t ubude bezingqimba zomhlabathi ngenhla komhubhe [m].
Lokhu kucatshangwa kwamukelwa kuphela ezimweni ezikhethekile, njengalapho inhlabathi engenhla komhubhe yakhiwa udaka olungenawo cishe nakancane ukumelana kwangaphakathi, noma ivela enhlabathini ehlanganisanayo nengahlanganisani emanzini angaphansi komhlaba, lapho ukumelana komhlabathi kungaphansi komphumela wesisindo somhlabathi.
Lezi zimo ziyivelakancane ekusebenzeni futhi ziphathwa njengezimo ezikhethekile. Kuzo zonke ezinye izimo, lapho kungabalwa ukumelana kwangaphakathi kwenhlabathi, ukunqunywa kwengcindezi yomhlaba emigedeni ngokwalokhu kucabangela akufanelekile, ngoba kunikeza ingcindezi enkulu kakhulu kuneyangempela.
Sl. 2. Ukunqunywa kwengcindezi yomhlaba emhubheni ngokucabangela ukuthi ingcindezi ikhula ngokulingana nokujula
Ukucabangela okusekelwe emithethweni yokulingana kwemizimba ewohlokayo
Sl. 3. Ukuthola ukucindezela komhlaba emhubheni ngokwesisekelo esisekelwe emithethweni yokulingana kwezidumbu ezibhidlikayo
Ngokwalesi sikhathi kuthathwa inhlabathi eyomile, ephukayo, futhi kucatshangwa ukuthi ingcindezi phezu kwekhothamo lephayiphi le-tunela incane kunesisindo seprizma ABA’B’ ngenxa yokusebenza kwamandla okuhlikihla ezindaweni eziqondile AA’ kanye BB’ (sl. 3).
Kulesi sisekelo kunamafomula amaningi asetshenziswa ukubala ingcindezi engaphezulu kwe-arch yetuneli, njengeka-Forcheimer, uBierbaumer kanye neka-Engesser.
Isisindo sonke senhlabathi ngaphezu kwe-arch yomhubhe sithi W= γ bt, kodwa iphrizimu ABA’B’ ngeke ikwazi ukushelela phansi ngokukhululeka, ngoba lokho kushelela kuzophikiswa ukungqubuzana kwento ezindaweni AA’ kanye BB’. Uma o liyikona lokungqubuzana kwangaphakathi kwenhlabathi ngaphezu kwe-arch yomhubhe, isilinganiso sokungqubuzana singu tgo, kanti ingcindezi evamile endaweni yokungqubuzana empeleni ingamandla aseceleni E, ukucindezela okusebenzayo komhlaba ezindaweni AA’ kanye BB’. Ngakho-ke kulezi zindawo zombili kusebenza amandla okungqubuzana
Q = Ea tg_ϕ._
Ingcindezi P esibhakabhakeni somhubhe, ingcindezi esiqongweni, ingu
Aktivni zemljani pritisak računa se po Rankinu
Ea = ½ γt2 tg2(45o – ϕ/2)
Ukubalwa kwengcindezi yomhlaba ethezweni ngokwale mbono kwenziwa kuyaqabukela futhi kuphela ezimweni ezithile, njengokuthi, isibonelo, lapho ukuphakama kwezendlalelo zomhlabathi ngaphezu kwethezi kukuncane, ukuze kungakwazi ukwakheka uthango lokukhulula umthwalo.
Ukuqagela kokwakheka kwekhothamo elikhulula umthwalo
Ngale ndlela, kunoma yiluphi uhlobo lwenhlabathi oluhlangene nolungahlangene, ngaphandle kodaka, kwakheka ngaphezu komhubhe umkhono wokwehlisa umthwalo, ukuze kuphrofayili yomhubhe kusebenze kuphela into engaphansi kwalowo mkhono, kanti wona umkhono uqobo ugcinwa ulingana ngenxa yesenzo se-arc, okuboniswe yizivivinyo enhlabathini yesihlabathi esixegayo. Ukuze kunqunywe ingcindezi yomhlabathi emhubheni ngokwalokhu kucabangela kunezindlela eziningana, phakathi kwazo ezaziwa kakhulu iKommerell neProtođakonov. Ngokwendlela kaKommerell kuthathwa ukuthi umkhono wokwehlisa umthwalo unomumo we-half-ellipse, kanti ngokwendlela kaProtođakonov unomumo we-parabola.
Indlela ka-Kommerell ye-semi-ellipse yokucindezela
Ngale ndlela kwamukelwa ukuthi ukuphakama kwe-vault yokukhulula h kuncike ebubanzini bomhubhe kanye ne-engeli yokungqubuzana kwangaphakathi kwenhlabathi lapho umhubhe uyembiwa khona (sl. 4). Ukuphakama kwe-vault yokukhulula h kunganqunywa ngokusekelwe kusibonelo:
h = 100_a_/p
lapho a kuwukwehla kokusekelwa kusukela ekuqaleni kokumba itunela kuze kuphele ukwakhiwa kwesembozo setunela, p kuwukuxega komhlaba okuhlala njalo.
Umdv. 4. Ukunqunywa kwengcindezi yomhlabathi emhubheni ngendlela ye-semielipse sengcindezi
Ngaphansi kwezimo ezivumayo kuthathwa a = 10 – 15cm, ngaphansi kwezimo ezingezinhle a = 15 – 40cm, ngaphansi kwezimo ezimbi kakhulu a = 40 – 70cm.
Ukuxegiseka okuhlala njalo kwenhlabathi p kunqunywa enhlabathini embiwe yetunela ngo-% ngemva kokumba nokuyiphinde icindezelwe. Amanani ka-p asukela emikhawulweni enikeziwe kuthebula 1.
Kodwa-ke, noma le fomula engenhla isetshenziswe kaningi kakhulu emsebenzini, kubhekwa ukuthi ayihambisani neqiniso. Ukwehla a akunalo inani eliphelele, kodwa kuhluka ngaphakathi kwento efanayo kuye ngohlobo lwesisekelo sokusekela. Uma isisekelo sokusekela siyinsimbi, ukwehla kuncane, uma singokhuni ukwehla kukhulu. Kuma-profile avamile wama-tunnel emizileni yezitimela nasemigwaqweni kwamukelwa ukuthi ngobude bongqimba lwenhlabathi ngenhla kwetunnel t > 20 m ukuphakama kwe-vault yokudambisa umthwalo h=20 m.
Ingcindezi eseceleni. NgokukaKommerell, ingcindezi eseceleni ivela ngenxa yesenzo sesisindo seprizimu yomhlaba ABC (umz. 4), ehlanganiswe ezinhlangothini ngendawo eshelelayo AC kanye nendiza emile yomhubhe AB, kanti phezulu ilayishwa yisisindo seprizimu yomhlaba CBG. Kulesi simo kuyamukelwa ukuthi i-prizimu yomhlaba esebenzayo ihlanganiswe phezulu ngendawo evundlile CB endizeni yesisu sodome lomhubhe
Itheb. 1. Amanani acishe abe khona omhlabathi p ngo-%
Njengoba indiza AB imi mpo, indiza CB ivundlile, kuthathwa ukuthi kunesimo sika-Rankine sengcindezi yomhlaba, nokuthi isiqondiso sengcindezi yomhlaba esebenzayo E siqondile. Ngokuka-Rankine, ukutsheka kwendawo yokushelela AC maqondana nokuvundlile kuse-engeli α=45o+ϕ/2, ingcindezi yomhlaba esebenzayo Ea yi
Ea = ½ _γh_2tg2(45o-ϕ/2),
lapho γ kuyisisindo somthamo womhlabathi ngo Mp/m3, h ukuphakama kodonga olusekelayo ngo m, ϕ i-engeli yokungqubuzana kwangaphakathi komhlabathi.
Njengoba iprizimu yomhlaba esebenzayo ABC ithwalwa phezulu isisindo seprizimu CBG, kulokhu kuzoba ngobude bomhubhe h’
Ea = ½ γ h’ 2tg2(45o-ϕ/2),
lapho γ1 = γ + 2p/h’
lapho p = Q/CB = Q/h’tg(45o- ϕ/2)
Isisindo Q sitholakala njengomehluko phakathi kwesisindo W sekota ye-ellipse yokucindezela CEF nesisindo W1:Q = W – W1.
Isisindo W sitholakala kusukela endaweni A yekota ye-ellipse kanye nesisindo somthamo womhlabathi γ, W = Aγ. Indawo A itholakala ngokwesisekelo sesibalo sendawo ye-ellipse: A = h·e·π/4
Ngokufaka inani le-p esibalweni se-Ea sithola:
Ea = ½ γ h’2 tg2 (45o-ϕ/2) + Q tg(45o-ϕ/2).
Ingcindezi yegobolondo enkulunkulukazi. Njengoba i-vault yokukhululwa ikwazi ukulingana maqondana ne-eksisi eqondile, ingcindezi enkulunkulukazi ingabalwa engxenyeni eyodwa yephrofayili yomhubhe. Isisindo W1 seqhugwane lomhlabathi BEFG ngobude bomhubhe 1,00 m ngu:
W1 = (z+h)/2 · b/2 · 1,00 · γ
Kulesi sibalo konke sekwaziwa ngaphandle kuka z, esikunquma ngokusekelwe esibalweni se-ellipse (sl. 5): b2x2 + a2y2 = b2a2. Esimeni sethu b=e; a=h; x=z;
Sl. 5. Ukubalwa kwengcindezi yeqembu lenhla ethempelini kusetshenziswa indlela ye-half-ellipse yomthwalo
Sl. 6. Ingcindezi esisekelweni p ngaphansi kwesisekelo
Ingcindezi yesisekelo. Njengoba kwamukelwa ukuthi ingcindezi yesisekelo A ilingana nengcindezi yesiqongo P, ngaleyo ndlela ubukhulu bayo bunqunywe.
Uma iphrofayili yomhubhe inesondlo esingezansi, ukucindezela phansi komhubhe p kungu: p = P/(b·1,00m) [Mp/m2].
Nokho uma lokhu kuqinile futhi kunamandla okuthwala anele, ingcindezi ye-ridge P idluliselwa ngezinsika ezinobubanzi d emhlabathini (isith. 6), ngakho-ke ingcindezi esezansi ngaphansi kwezinsika ithi: p = P/(2d·1,00m) [Mp/m2].
Kuyaphawulwa ukuthi kuleli cala kuyadingeka ukwenza ukuhlolwa kwendawo nokunquma umthamo wokuthwala kanye nokuhlala phansi kwenhlabathi, ngoba kuye kwenzeka ukuthi umthamo wokuthwala wenhlabathi ube mncane kunengcindezi yesisekelo, ngenxa yalokho kwavela ukuguquguquka kokumbozwa komhubhe nokuhlala phansi komhubhe wonke.
Ukuqagela okusekelwe emithethweni ye-elasticity
Ezikhathini zakamuva kuvele umbono omusha, wokuthi inhlabathi ibhekwe njengomzimba oyisigaxa one-elasticity ofanayo no-isotropic lapho kungasetshenziswa khona imithetho ye-elasticity. Ngokwalo mbono, ama-eksisi e-elastic enhlabathi achazwa yi-modulus yayo ye-elasticity E kanye ne-Poisson coefficient µ encike ezicini zomzimba zenhlabathi. Nokho eqinisweni inhlabathi ayiyona i-isotropic, kodwa iyinqwaba ye-anisotropic, amanani ayo e-modulus E kanye ne-coefficient µ aguquka ngokujula. Noma kunjalo, naphezu kwalokhu kuchezuka, ukusetshenziswa kwethiyori ye-elasticity ekunqumeni ingcindezi yomhlaba kunentshisekelo enkulu yesayensi namathemba ocwaningo lwesikhathi esizayo.
Ukuhlolwa kokuzinza komgqomo wethelevishini ngaphansi kwengcindezi yomhlaba
Ukuhlola ukuzinza kohlaka lwe-tunnel kukhethwa i-cross-section yohlaka, lapho kusiza khona ukusebenzisa izibonelo zamathunela akhiwe ngaphambilini ngaphansi kwezimo ezifanayo nezasesimweni esithile, agcine esesimweni esihle, noma-ke kukhethwe i-cross-section yohlaka lwe-tunnel ngendlela ethile ye-empirical (sl. 7a). I-cross-section ekhethiwe yohlaka lwe-tunnel ihlukaniswa ibe ama-lamella ngobubanzi obufanayo uma kungenzeka Δs. Ku-lamella ngayinye kunqunywa ingcindezi eqondile neyaseceleni, kanye nesisindo selamella uqobo.
Ukucindezela okuqondile PG ku-lamela ngobude bomhubhe 1,00 m (sl. 7a) kutholakala ngokusekelwe efomini:
PG = (y1+y2)/2 · Δ_x_·1,00·γ
Sl. 7. Ukunquma ingcindezi yomhlaba emhubheni ngokwendlela ka-Kommerll
Ingcindezi eseceleni yakhiwa ingcindezi yomhlaba Eh, kuphrofayili yomhubhe enobude h’ kanye nengcindezi Ea ngenxa yesenzo somthwalo Q
Eh’ = ½ γ h’2 tg2 (45o-ϕ/2); Ea = Q tg(45o-ϕ/2).
Ukuze kunqunywe ingcindezi eseceleni Eh kuma-lamela athile okuvalela, kudwetshwa idiyagremu yengcindezi eseceleni (7a) ngokusekelwe kwizibalo ezilandelayo:
Amandla PG kanye Eh asebenza kuma-eksisi amalamela ahambisanayo.
Ngaphezu kwalokho kunqunywa nesisindo se-lamela lolwelwesi PZ, esisebenza endaweni yalo yokuminyana, bese kutholakala i-resultanti R yawo wonke amandla kulelo lamela (sl. 7b). Ngale ndlela kunqunywa ama-resultanti R1, R2, R3 kuwo wonke ama-lamela (sl. 8a), ahlanganiswa kuhlelo lwamandla (sl. 8b), bese kutholakala i-resultanti Rn. Bese kusukela kupholo elikhethwa ngokukhululekile O kudonswa imisebe bese kudwetshwa umugqa wokuqala wokusekela ac. Kusukela esimweni sokuthi ikhothamo lisesezingeni lokulingana uma ingcindezi evundlile yekhothamo H, i-resultanti yengcindezi yenhlabathi ku-tunela _R_n ne-ingcindezi yesisekelo A ihlangana endaweni eyodwa, sithola iphuzu lokuhlangana S. Uma leli phuzu lihlanganiswa nephuzu eliphakathi lesixhumanisi sekhothamo esisekelweni, sithola umugqa wengcindezi entsha yesisekelo A1. Uma sihlanganisa amandla Rn, A1 no H kuhlelo olusha lwamandla (sl. 8c), sithola ubukhulu H kanye nepholo elisha O1 lapho sidonsela khona imisebe emisha kanye nomugqa wesibili wokusekela ac’.
Sl. 8 Uhlelo lwamandla kanye nolayini osekelayo wengcindezi yomhlabathi emhubheni
Ngokohlu olusha olutholakele lokusekela, iphrofayili enqamulelayo yolayini womugqa womhubhe iyalungiswa, futhi umgqa wokusekela uyakhiwa, uma kudingeka, nangokwesithathu. Umgomo uwukwamukela umumo onjalo welayini womhubhe, lapho i-eksisi yayo ihlangana khona nolayini wokusekela. Kuleso simo, kubusa kuphela izingcindezi zokucindezela kulayini. Ingcindezi yokucindezela evela kunoma iyiphi ingxenye enqamulelayo n – n yolayini womhubhe (sl. 8), itholakala ngokomfomula
lapho N kuyisakhi esivamile somphumela Rn esigabeni sokumbozwa n – n , esitholakala kusukela kulo mdwebo wamandla wale ngxenye; d ukujiya kokumbozwa komhubhe esigabeni n – n; e ukudedelana kwamandla ahlaselayo N kuleso sigaba esifanayo.
Ukucindezeleka kokucindezela σ kufanele kube kuncane kunokucindezeleka okuvunyelwe kwesembozo. Kuma-vault omhubhe enziwe ngosimende oqiniselwe ngensimbi kubhekwa ukuthi le ndlela ayinembi ngokwanele, ngakho-ke kunconywa indlela kaSpangerberg.