Okuqukethwe kwengcweti yenqolobane nengozi engathi sína: i-athikili igcina i-akhawunti yomlando yokusimama kwemithambeka, izimpawu, amafomula nemidwebo evela embhalweni wokuqala. Akulona ucwaningo lwe-geotechnical, ukumba noma iphrojekthi yokuhlanganisa, ukubala ukuzinza, uhlelo lokudonsa amanzi, ukuhlolwa kokudilika komhlaba noma imiyalelo yomsebenzi. Umthambeka ongazinzile ungangcwaba abantu, izakhiwo nemigwaqo ngokuzumayo; imifantu eboniwe, amaqhubu, amanzi aguqubele, ukwehla kungazelelwe noma ukususwa endaweni kufanele kuthathwe njengesizathu sokusuka endaweni eyingozi kanye nokuhlolwa okuphuthumayo kochwepheshe.
Namuhla, i-Savo Kusić igxile emafasiteleni okhuni, amafasitela okhuni-aluminium, amafasitela ngokwezifiso, umnyango kanye nezicelo zekhotheshini. Lesi sihloko sihlala siyingobo yomlando yobuchwepheshe futhi asimeleli ukunikezwa kwedizayini ye-geotechnical, ukugadwa noma ukwenziwa kwemisebenzi yomhlaba.
Emisebenzini eyakhiwe yomhlaba efana nokusikeka, imiphetho namamisele, amamithambeka okugcina kwesinye isikhathi ayawa. Futhi umthambeka wemvelo, ngaphandle kwemisebenzi yokwenziwa, ungahamba ngokuzumayo nangamandla amakhulu noma kancane kakhulu. Lezi zenzakalo kade zaba yisihloko sezifundo ze-geological kanye ne-geomechanical, ngenhloso yokuhlola ukuzinza kusukela ezicini ezibonakalayo zenhlabathi kanye nezimo zecala ngalinye.
Izimbangela zokunyakaza kwezindimbane zomhlaba
Isimo sokuzinza kwanoma iyiphi inhlabathi, kungakhathaliseki ukuthi into yobumba yokwenziwa noma inhlabathi yemvelo, ukuthi kukhona ukulingana phakathi kwamandla angaphandle nokumelana kwangaphakathi kwenhlabathi. Amandla angaphandle ngokuyinhloko isisindo senhlabathi ngokwayo, okuvame ukuba amandla angaphandle kuphela, alandelwa yinoma yimuphi omunye umthwalo wangaphandle osebenza emthambekeni, unomphela noma onyakazayo. Ukumelana kwangaphakathi kuhlanganisa ukubumbana kanye nokuklwebhana enhlabathini eboshiwe, kanye nokungqubuzana kuphela enhlabathini engaboshiwe.
Fig. 1. Ukuthambekela kodonga lomhlabathi oluxegayo
Uma sibona uthango lobude h olwenziwa ngenhlabathi exege ngokuphelele, isibonelo isihlabathi esiminyene esomile, sizonquma ukuthi ukuthambekela kwalolo donga kutshekiswe nge-engeli β ukuya evundlile (fig. 1). Ubukhulu be-engeli β buncike ezicini eziningana njengosayizi wokusanhlamvu, ukwakheka kokusanhlamvu nokuhlangana. Uma sinyusa ubude be-engeli h ukuya ku-h1, h2, njll. ngento efanayo engaboshiwe yokuhlangana okufanayo, i-engeli engu-β ngeke ishintshe, i-engeli ye-engeli izohlala ku-slope efanayo ifike kubude obungenamkhawulo h. Emhlabathini othile oxekethile, i-engeli yemvelo ye-slope engu-β izimele kunobude bomthambeko h. Usayizi we-engeli β yomhlabathi ongaboshiwe uncike engeli lokungqubuzana kwenhlabathi yangaphakathi engu-φ futhi kucatshangwa ukuthi incane kakhulu kunayo, noma ilingana nayo, β ≤ φ.
Fig. 2. Ukusika ukuthambeka emhlabathini oboshiwe
Uma sibheka ukusikwa okwenziwe enhlabathini eboshiwe, sizothola ukuthi ukuthambekela kokusikwa kugcinwe ngaphansi komthambeko oqinile.1:m, i.e. nge-engeli enkulu β ngenxa yokuthi ukumelana kwangaphakathi kwenhlabathi eboshiwe kwanda ngokuhlangana, okungekho esihlabathini esomile (isib.2). Ezinhlotsheni ezithile zenhlabathi, njenge-loess eyomile, ukubumbana kungakhuphula ukumelana kwangaphakathi kuze kufike ezingeni lokuthi inhlabathi ingabanjelwa ngohlangothi olusikwe ngokuqondile, okungukuthi nge-engeli β =90°. Kodwa-ke, uma senyusa ubude bokusika h enhlabathini eboshiwe kuye ku h1, h2 njll., i-engeli yokuthambekela ye-bevel ye-cut β kumele yehliswe ukuze kugcinwe i-bevel isesimweni. Ku-engeli ngayinye ye-slope engu-β yethambeka lokusikwa enhlabathini ethile eboshiwe kunokuphakama okukodwa okubalulekile okungu-hc. Uma seqa lobu bude, umthambeka AB ngeke ugcinwe ulingana futhi uzoshelela endaweni eshelelayo CD (fig.3). Ukushelela kwenzeka ngenxa yokuphazamiseka kwebhalansi phakathi kwamandla angaphandle, isisindo somzimba womhlaba kanye nokumelana kwangaphakathi, okwakungasenele ukuphikisa amandla angaphandle akhulayo, okungukuthi isisindo esandayo sesisindo senhlabathi esibangelwa ukwanda kokuphakama komthambeko h.
Sl.3. Umqansa wokusikwa enhlabathini ebumbene
Kusukela ngenhla, kulandela ukuthi i-angle ye-slope yemvelo yenhlabathi ayikwazi ukwamukelwa njengenani eliqhubekayo lenhlabathi enikeziwe, ngoba inani layo ngaphansi kwazo zonke ezinye izimo lincike ekuphakameni komthambeko futhi liyancipha ngokunyuka kwalokhu kuphakama. Kodwa-ke, kuvame ukwamukelwa emithambekeni yobude obuncane njengenani elihlala njalo, kuncike engeli lokungqubuzana kwenhlabathi yangaphakathi φ.
Ukuphazamiseka kokulingana kungenzeka futhi ngaphandle kokukhulisa ubude obunqunyiwe h, isibonelo lapho ukumelana nenhlabathi yangaphakathi kuncipha. Izakhi zokumelana kwangaphakathi kwenhlabathi eboshiwe, ukubumbana nokungqubuzana, ziyahlukahluka kakhulu futhi zincike enanini lamanzi enhlabathini. Ngakho-ke, ezimweni eziningi, imbangela yokushelela iwukugcwala ngokweqile komhlabathi oboshwe ngamanzi, okungaba mkhulu kangangokuthi inhlabathi ayisakwazi ukuzisekela ngaphansi kwanoma yimuphi umthambeko, kodwa i-slide ngenxa yesisindo sayo.
Fig. 4. Ukushelela komhlabathi ngenxa yokwakheka kwezindawo ezishelelayo
Kunezimo ezihlukahlukene zokushelela kwenhlabathi ngenxa yokunciphisa ukumelana kwangaphakathi, esizokubalula lapha izici ezimbalwa.
Imfundo yezindawo ezishelelayo
Uma kukhona ungqimba lobumba olungangeneki emthambekeni ongaphansi kongqimba olungaphezulu lwenhlabathi evunyelekayo (fig. 4a), noma uma kukhona ungqimba lwesihlabathi oluthambekele kungqimba lobumba (fig. 4b), lapho amanzi edonsa khona i-atmospheric (for the surface negle) amanzi aphuma emkhathini (for the negle). ukudilika komhlaba kungenzeka. Inani elikhudlwana lamanzi lidlula ungqimba olukwazi ukungena ongqimbeni lobumba, olumanzisa kakhulu, lunciphise ukumelana kwalo phezulu, lapho ungqimba olungaphezulu lushelela khona.
Ukuphazamiseka kwebhalansi ngokusika ukusika
Ukusika ama-cuts ngesikhathi kwakhiwa imizila yezitimela nemigwaqo kuphazamisa isimo sangaphambilini sebhalansi, ngoba kuphrofayili esikiwe inhlabathi ihlala ingenakho ukusekela futhi ijwayele ukuya phansi ngenxa yamandla adonsela phansi. Isimo sokulingana singagcinwa uma ukumelana kwangaphakathi kwenhlabathi kukukhulu ngokwanele ukulwa nalokhu kuthambekela, okungenzeka futhi uma inhlabathi esikiwe iqukethe izendlalelo ezithambekele ngokuqinile ekusikeni.
Fig. 5. Ukushibilika kwezwe ngenxa yokusikwa enhlabathini egqinsiwe
Nokho, uma izingqimba zenhlabathi engangenisi nengenamanzi zisikwa ngokushintshana (Fig. 5), kunethuba lokucwiliswa kwenhlabathi engenisa amanzi kanye nokumanziswa kwenhlabathi engangenisi, lapho kungenzeka khona ukushelela.
Ukungafani komhlabathi
Izendlalelo ezizacile zento engakwazi ukungena emanzini onqenqemeni owenziwe ngenhlabathi evuzayo, okuthiwa amalensi obumba (fig. 6), nazo zingabangela ukushelela uma inani elikhulu lamanzi lifinyelela kuzo futhi lenze indawo eshelelayo.
Fig. 6. Ikesi lokushelela kwe-embankment ngenxa yokwakheka okungahambisani
Umthelela wesithwathwa
Ngaphansi komthelela wesithwathwa, amanzi anqwabelana kungqimba olungaphezulu ngendlela yamalensi eqhwa. Ngesikhathi sokuncibilika, amalensi eqhwa aphenduka amanzi, agxilise inhlabathi ekujuleni kwesithwathwa, okubangela ukuthi ibe uketshezi futhi ilahlekelwe ukuzinza.
Lesi simo senzeka kuphela enhlabathini eyingozi yesithwathwa kanye nesithwathwa esithatha isikhathi eside, ngoba kuthatha isikhathi esiningi ukwakhiwa kwamalensi eqhwa.
Ukwehla kwamanzi angaphansi komhlaba
Uma izinga lamanzi angaphansi komhlaba lehliswa unomphela, isibonelo ngenxa yomsebenzi owenziwa emhlabathini, inhlabathi iyoma futhi, uma kuwubumba oluvuvukele kakhulu, kuvela imifantu. Amanzi amaningi angaphezulu nasemkhathini angena kuwo, amanzise inhlabathi futhi anciphise ukumelana kwawo nangaphakathi, okungaholela nasekubhidlikeni kwenhlabathi.
Kukhona nezinye izimo eziningi zokushelela kwezwe, ngakho-ke kungacatshangwa ukuthi noma iyiphi inhlabathi ehlangene, ngaphansi kwezimo ezithile, ingalahlekelwa ukumelana kwayo kwangaphakathi ngezinga elikhulu noma elincane futhi, ngaphansi kwethonya lamandla angaphandle, iqalise ukunyakaza.
Inhlabathi engahlangene izinzile inqobo nje uma i-engeli yokuthambekela komthambeka incane kune-engeli yokungqubuzana kwangaphakathi kwenhlabathi. Ngalolu hlobo lwenhlabathi, ukushelela kwenzeka kuphela uma i-engeli ye-slope inkulu kune-engeli yokungqubuzana kwangaphakathi. Kodwa-ke, uma udonga lwenziwe ngezinto ezingaboshiwe enhlabathini yobumba, inhlabathi enobumba ingase ishelele futhi uthango lugoqe, futhi kuyadingeka ukuhlola ukusimama.
Ihlola ukuqina kwemithambeka yomhlaba
Isimo sendawo eshelelayo
Isimo sebhalansi phakathi kwamandla angaphandle nokumelana nenhlabathi yangaphakathi sabekwa u-Coulomb ngesibalo sakhe
τ ≤ c + σ tgϕ
lapho τ ingcindezi yokugunda inhlabathi, c ukuhlangana, σ ingcindezi evamile endaweni eshelelayo, ϕ iyi-engeli yokungqubuzana kwangaphakathi.
Uma ukumelana kwenhlabathi kwangaphakathi, ukubumbana c kanye nokukhuhlana σ tgϕ kunganele ukuphikisa ukugunda kwenhlabathi, ukushelela kwenzeka endaweni eshelelayo ngaphakathi enhlabathini. Kunezinhlobo ezahlukene zezindawo ezishelelayo, ezincike ezintweni ezibonakalayo zenhlabathi, ukuhlukaniswa, umswakama, umthwalo wangaphandle nezinye izici.
Amakesi okuslayida alandelayo ajwayelekile ayahluka ngokuya ngendawo:
Fig. 7. Izimo ezijwayelekile zokudilika komhlaba
a) Ukuslayida kwezinhlangothi eziqondile zokusikwa. Endabeni yamashaneli okuphakelwa kwamanzi, ukuthuthwa kwendle, njll., ambiwa ngezinhlangothi eziqondile (fig. 7a), uma ubude obubalulekile hc, obuncike ezintweni ezibonakalayo zomhlabathi, budlula, ukuslayida phezulu ADC kwenzeka. Lezi ziliphu ngokuvamile azikho kubo bonke ubude bomzila, kodwa zenziwe zasendaweni, okuchazwa amandla angalingani okugunda enhlabathi.
b) Ingxenye yeslope eshelelayo (fig. 7b). Lezi ziliphu zivame ukuvela entwasahlobo endleleni kaloliwe kanye nemigwaqo futhi ziwumphumela wokugcwala ngokweqile komhlabathi ngamanzi.
c) Ukushelela kweslophu ebusuku (fig. 7c). Iwukushelela kwawo wonke umthambeko wokusikwa noma uthango ukuya emlenzeni C.
d) Islowuphu esislayida ngaphansi kwezinyawo (Fig. 7d). Kuwukushelela kwawo wonke umthambeka wokusikwa noma uthango kanye nomhlabathi ongaphansi konyawo. Lesi silayidi sibizwa nangokuthi ukuphuka kwe-subgrade noma i-Swedish fracture, ngemva kwabaseSweden abasichaze kuqala.
Mayelana nokwakheka kwendawo eshelelayo, kungafunwa kuphela ukuthi indawo eshelelayo enhlabathini eboshiwe ayiqondile, kodwa iyindawo egobile. Ababhali abathile bathatha i-arc eyindilinga (Fellenius), i-logarithmic spiral (Rendulić) noma inhlanganisela yale migqa egobile (i-Brinch Hansen) njengomumo wendawo eslayidayo.
Umphumela wokuhlunga kwamanzi ekuzinzeni kwemithambeka
Uma kunamanzi angaphandle phambi komthambeka anezinga elingu-N1 (isib.8), ukugeleza kwamanzi kwenzeka enhlabathini ngemuva komthambeka, okubangela ukucindezela kwamanzi kwangaphakathi ezimbotsheni, ngenxa yalokho ukungqubuzana phakathi kwezinhlayiya eziqinile kuncipha futhi ukucindezeleka kwe-shear emhlabathini kwanda.
Uma izinga lingu-N1 lamanzi phambi komthambeka ikholomu engaguquki, yamanzi H*γW ibangela umfutho wamanzi ezimbotsheni zenhlabathi, okunciphisa ukungqubuzana phakathi kwezinhlayiya eziqinile, ngenxa yalokho ingozi yokushelela kwe-slope iyanda. Nokho, lapho izinga lingu-N1 ngokungaguquki, ukucindezela kwekholomu yamanzi H*γW kuphusha izinhlayiya eziqinile ziye endaweni engaphakathi yomhlabathi, ngenxa yalokho ingozi yokushelela kwe-slope iyancipha ngokwezinga elithile. Kulokhu, ezingeni lamanzi njalo N1 phambi komthambeka, kunengozi yokushibilika komthambeka ongezansi komfula, ngoba umphumela wokuhlunga kwamanzi enhlabathini kubangela ukusunduza kwezinhlayiya eziqinile zibheke ohlangothini olungaphandle lomthambeka ongezansi komfula.
Sl.8. Umphumela wokuhlunga ekuzinzeni kwethambeka lomhlabathi
Uma izinga lamanzi langaphandle lehla kakhulu lisuka ku-N1 ku_N2_ khona-ke ukuzinza komthambeka okhuphuka nomfula kusengozini. Kulesi simo, amanzi angaphakathi ageleza abheke ohlangothini olungaphandle lomthambeka okhuphuka nomfula, esunduza izinhlayiya eziqinile zibheke kulolo hlangothi.
Ngenxa yakho konke lokhu, uma umthambeka wenhlabathi ucwiliswa emanzini, umphumela wokuhlunga kwamanzi kufanele futhi ucatshangelwe lapho kuhlolwa ukuzinza komthambeka.
Umthelela wokuhlunga kwamanzi enhlabathini uncike ezicini eziningana, ezibaluleke kakhulu ukungena kwenhlabathi, ingcindezi ye-hydrostatic yamanzi angaphandle, izinga lokuncipha kwezinga lamanzi angaphandle kanye nokulingana kwenhlabathi.
Uma sicabanga ukuthi udonga olukufig. 8 yesisindo se-homogenously isotropic, ngaphansi komthelela we-hydrostatic pressure yamanzi angaphandle weleveli N1, amanzi azogeleza ezimbotsheni zothango elibheke endaweni eyehlelayo eyehla nomfula, lapho izinga lamanzi angaphansi komhlaba onqenqemeni lizokwehla ngobude bomgwaqo ohanjwayo. Uma sethula amapayipi e-piezometer AA’, BB’ kanye ne-CC’ ku-embankment (fig. 9), amanzi ambotshana angaphansi komphumela we-hydrostatic pressure azongena kulawa mapayipi futhi akhuphuke aye kuleveli engu-N1, engafana kuwo wonke amapayipi, uma lezo zindawo _B zikhethiwe futhi_B_A. ikholomu yamanzi emapayipini ithi h1, h2 kanye no-h3.
Fig. 9. Equipotential kanye nemigqa yamanje
Uma sisho ngo-h ukuphakama kwezinga lamanzi N1 ngokuhlobene nendiza ethile ekhethwe ngokungafanele i-O-O, khona-ke amandla okuthi h awo wonke 3 amaphoyinti, A, B kanye nokuthi C kuyefana. Umugqa oxhuma lawa maphuzu amathathu umugqa equipotential. Amanzi angaphansi komhlaba awakwazi ukugeleza kulowo mzila, kodwa aye ngasemaphoyintini anamandla aphansi.
Ngendlela efanayo singakhetha ngobuningi obufanayo amaphuzu D, E kanye F ngamandla aphansi h ― Δh. Ulayini ohlanganisa lawa maphuzu amathathu umugqa we-equipotential wamandla okuthi h ― Δh. Ukugeleza kwamanzi ukusuka endaweni engu-A yomugqa we-equipotential ABC ukuya endaweni ethile esondele kakhulu D yomugqa we-equipotential DEF izoba khona lapho uya khona lapho kunokwehla okukhulu kakhulu kwe-hydraulic _imax_ebanganini elincane = _ibanga elincane_elincane kakhulu =Δil_ibanga elincane AD. Lokhu kusho ukuthi ulayini AD okugeleza kuwo amanzi uncike kuyo yomibili imigqa ye-equipotential, ngoba
imax = Δh / Δlmin
lapho Δlmin ijwayelekile kuyo yomibili imigqa ye-equipotential. Lezo zimo ezijwayelekile emigqeni ye-equipotential ziyizikhombisi-ndlela zokugeleza kwamanzi ngesisindo esingavulekele futhi zibizwa ngokuthi imigqa yamanje. Umphakathi wemigqa ye-equipotential neyamanje, encikene komunye nomunye, wenza inethiwekhi yokugeleza.
Amanethiwekhi agelezayo anomumo ohlukile ngokuya ngenqwaba yokungena. Icala elivame kakhulu uthango olwenziwa ngesisindo esingeneka emhlabathini ongangeneki, okungukuthi enhlabathini engenziwa ingangenisi (fig. 10). Kulesi simo, uma izinga lamanzi langaphandle lingaguquki, ama-streamlines ayingxenye yawo emaphakathi ye-parabola.
Fig. 10. Inethiwekhi egelezayo onqenqemeni olungenekayo emhlabathini ongangenisi
Emthambekeni okhuphuka nomfula, ama-parabola axhuma nemigqa eqonde emthambekeni, emele umugqa we-equipotential, ngoba kuleveli engashintshi N1 amanzi awahambi ehle ngomthambeka. Ngomthambeka ongezansi komfula, ama-parabola agcina ngokuhlangene emthambekeni, ongewona umugqa we-equipotential noma umugqa wamanje. Ingaphezulu lenhlabathi engangenwa amanzi ngaphansi konqenqema liwumzila ogelezayo, ngoba amanzi angaphansi kodonga ageleza ngokuhambisana nalokhu. Engxenyeni engenhla, inethiwekhi yokugeleza iphetha nge-parabola eyisisekelo ebizwa ngokuthi seepage line, emele umngcele wenhlabathi ngaphansi kwesenzo sokuhlunga. Ngaphansi kwalo mkhawulo, inhlabathi ingaphansi komphumela wokuhlunga ngenxa yokucindezela kwe-hydrostatic kwamanzi angaphandle H*γW, kuyilapho kungekho ukuhlunga emhlabathini ongaphezulu kwawo. Ulayini ogelezayo ubizwa nangokuthi umugqa wokugcwalisa, njengoba kucatshangwa ukuthi inhlabathi engaphansi kwawo igcwele amanzi ngokuphelele, kuyilapho ngaphezu kwawo igcwele kancane.
Ukuhlola okungokoqobo komthambeka kufanele kubandakanye uphenyo, ukuhlukanisa, imingcele yamandla, amanzi angaphansi nangaphezulu, ukuguqulwa kwezinga, ukugeleza kwamanzi, ukuzamazama komhlaba, ukumba noma izigaba zokugcwalisa, izakhiwo eziseduze nezimo zesikhashana. Ukumba ngaphandle kokuvikela okufanele kanye nokungena endaweni okungenzeka ukuthi ibhilikile akuphephile ngokusekelwe kumbhalo ojwayelekile noma ukuma komthambeka ngokwawo.