Inqaku lengcali elibalulekileyo: Eli nqaku luphononongo lwemfundo yoovimba kwaye ayilophononongo lwe-geotechnical, umgangatho osemthethweni welebhu, ubalo lwesiseko okanye incwadi yemiyalelo. Amagama okuqala, iinkqubo, iiyunithi zokulinganisa, amaxabiso, ukuhlelwa kunye neembekiselo “kwimimiselo yethu” zaye zakhutshelwa ngaphandle kokukhangela ukuthotyelwa kwemigangatho kunye nemimiselo esebenzayo. Uvavanyo lomhlaba, ukhetho lwendlela, ukuchazwa kweziphumo kunye nezigqibo zokuyila kufuneka zenziwe ziingcali ezigunyazisiweyo ze-geotechnical kunye nebhubhoratri efanelekileyo yento ethile kunye nendawo.
Isihloko sokucinezeleka komhlaba asiyonxalenye yesibonelelo esitsha sikawonke-wonke se-Savo Kusić. Ugxininiso lwangoku lwemveliso lubandakanya iifestile zomthi, iifestile zomthi-aluminiyam kunye neengcango ezenziwe ngokwezifiso. Ngefestile ethile okanye iprojekthi yocango, ungathumela isicelo sekowuti.
Isiseko sovavanyo lwe-edometer
Ukunyanzeliswa komhlaba kumiselwa ngovavanyo loxinzelelo olunothintelo lokwandiswa kwecala, olukwabizwa ngokuba luvavanyo lwe-oedometer okanye uvavanyo lokudibanisa.
Uvavanyo lwenziwa ngeesampuli ezingaphazamisekiyo, kwaye kwezinye iimeko ezinokuphazamiseka. Kwimeko yokuqala, isampuli yovavanyo ithathwa ngokucinezela amakhonkco esinyithi kwisampulu enkulu, engaphazamisekiyo, ethi emva koko ifakwe kwi-apparatus kunye neringi emva kokunqunyulwa kwesampulu engaphezulu kunye nokulinganisa imiphezulu yayo ngemiphetho ye-cylinder. Kwimeko yesibini, iringi izaliswe isampuli kwisimo sokuhambelana kwinqanaba lesivuno kwaye kuloo meko ifakwe kwi-oedometer.
Uvavanyo lwenziwa kusetyenziswa isixhobo esaqala ukwakhiwa nguTerzaghi saza sabizwa ngokuba yiOedometer. Namhlanje, kukho ulwakhiwo oluninzi olwahlukeneyo lwesi sixhobo, kodwa zonke zisekwe kumgaqo ofanayo, ukuvavanya ukucinezelwa kwesampulu yomhlaba phantsi komthwalo ngothintelo lokwandiswa kwecala.
I-Oedometer: inkcazelo yesixhobo
Fig. 1. Odometer
I-Oedometer iqukethe i-cylinder yensimbi apho isampuli ifumaneka phakathi kwamatye amabini okucoca (umkhiwane 1). Isampuli ingeniswe kwi-apparatus kwindandatho yensimbi kunye nobubanzi be-7-10 cm kunye nobude be-1-4 cm. Umthwalo P ukhutshelwa kwisampulu ngelitye lokucoca elingaphezulu. Ngaphantsi kwelitye lokucoca elisezantsi, kukho iziteshi ezisezantsi kwi-cylinder zokukhupha amanzi ukusuka kwisampuli ukuya kwi-capillary tube, kunye nokubonelela ngamanzi. Ekubeni ukunyanzeliswa kwesampuli kwenziwa ngeendleko ze-pores, ngenxa yokuba iincinci zomhlaba eziqinileyo kunye namanzi kwi-pores ziyinto engabonakaliyo, kuyimfuneko ukuqinisekisa ukuba amanzi aphuma kwisampuli ngexesha lovavanyo, olwenziwa ngokusetyenziswa kwelitye lokucoca, umjelo kunye nombhobho we-capillary.
Kwicala lasekhohlo lesixhobo ngumbhobho wokuhambisa amanzi kunye nompompo phambi kwe-cylinder, ngelixa i-tube ye-capillary isecaleni lasekunene, kunye nompompo emva kwe-cylinder. Ityhubhu ye-capillary ikwanceda ekumiseleni i-coefficient yokungena komhlaba k.
Uvavanyo
Xa isampuli ifakwe kwi-cylinder kunye ne-apparatus ihlanganiswe, vala ipompo ekhohlo, unikezelo lwamanzi, kwaye uvule itephu elungileyo, ukuze amanzi ahambe kwi-tube ye-capillary. Emva koko umthwalo wesampuli usondela, osetyenziswa ngokuthe ngcembe. Le mithwalo ilandelayo idla ngokusetyenziswa:0,50;1,00;2,00;4,00;6,00kp/cm2kwaye ukuqhubela phambili ukuya kumthwalo ophezulu womhlaba olindelekileyo phantsi kwesakhiwo, ubukhulu becala ukuya kuthi ga10kp/cm2, kunye namadama kunokuba ngakumbi20kp/cm2. Kwinqanaba ngalinye lomthwalo, ngexesha lokusetyenziswa kwayo, isitophuwashi siqaliswa kwaye ngamaxesha athile15“,30“,1’,2’,5’,15’,45’,2h5h24h, emva koko ngokuqhubekayo24h, de kube ukuhlanganiswa kwesampuli phantsi kwelo nqanaba lomthwalo, ukuhlaliswa okuhambelanayo kwiwaka le-millimeter kufundwa kumqhathanisi kwaye kubhalwe kwirekhodi. Udibaniso kucingelwa ukuba luphunyeziwe ukuba ulungiso lwesampulu luyi Δh ≤0,02 mmngenxa yexesha24yure. Emva kokuba ukuhlanganiswa kuphunyeziwe, umgangatho olandelayo womthwalo usetyenziswa kwaye yonke inkqubo iphinda iphindwe ngendlela efanayo kwaye kuze kube yilapho inqanaba lokugqibela lomthwalo.
Uvavanyo lokudibanisa kunye nokwandiswa kwecala elikhuselweyo lwenziwa ngokulayishwa kunye nokulayishwa, ukwenzela ukuba kunqunywe iimpawu ze-elastic zomhlaba. Emva kokulayisha isampuli ukuya kwinqanaba elithile, siyayikhulula ngokucotha okufanayo njengoko siyilayisha. Uncedo lukholisa ukwenziwa emva koko2,0kp/cm2,4,0kp/cm2kwaye6,0kp/cm2.
Njengomthetho, uvavanyo lwenziwa ngesampuli phantsi kwamanzi, ebanjwe kwi-tube yeglasi ekhohlo ekuphakameni kwendawo ephezulu yesampuli kwi-apparatus. Ukuvavanya ukunyanzeliswa kwesampuli kubukho bamanzi kwenziwa ngenxa yesi sizathu, kuba uvavanyo luthatha ixesha elide kwaye isampuli yoma ngelo xesha, ngenxa yoko ukunyanzeliswa kwesampuli kuya kuba ngaphantsi koxinzelelo lokwenene lomhlaba kwimeko yokufuma kwendalo. Ukongeza, ukufuma komhlaba wendalo kunokuba phezulu kunokuba kwakunjalo ngexesha lokuthatha iisampulu, ngakumbi xa umgangatho wamanzi aphantsi komhlaba unyuka, nto leyo enokukhokelela ekuphambukeni okubalulekileyo ekucinezelekeni komhlaba ngexesha lomgangatho ophezulu wamanzi.
Iziphumo zovavanyo zisetyenziswa kwiintlobo ezintathu zedayagramu, ezizezi, idayagram yoxinzelelo olunxulumeneyo, idayagramu yokutshintsha i-porosity coefficient kunye nedayagramu yolungiso lwexesha.
Umzobo woxinzelelo ohambelanayo
Lo mzobo ufunyenwe xa uxinzelelo oluqhelekileyo lusetyenziswa kwisampulu kwi-abscissa axis σ = P/A, apho P ngumthwalo osebenza kwisampulu ngelitye lokucoca eliphezulu kwi kp/cm2, A yi-cross-sectional aratus ye-axis isalamane kunye ne-compress kwi-app ehambelanayo Δh/h apho Δh kukuhlaliswa kwesampulu phantsi komthwalo Δσ ngexesha lokudibanisa, h ubude besampulu phambi kokulayisha (umkhiwane 2).
Fig. 2. Isalamane soxinzelelo lwedayagram
Ngexesha lokulayisha, umzobo woxinzelelo oluphambili a.
Ngexesha lokukhulula, ukuba ukungeniswa kwamanzi okungathintekiyo kunikwe amandla, ukwenzela ukuba isampuli ihlale phantsi kwamanzi ngexesha lokukhulula, ibuyela kwisimo sayo sokuqala, oko kukuthi ukuvuvukala. Nangona kunjalo, isampuli ayibuyeli kwisimo sayo sokuqala, oku kuthetha ukuba uye wafumana iplastiki (isigxina) deformation ngaphezu kwe-elastic. Ngoko ke, kule meko, umzobo wokuvuvukala b ufunyenwe ngexesha lokukhulula. Nangona kunjalo, ukuba uvavanyo lwenziwe ngaphandle kokufumana amanzi, endaweni yomzobo wokudumba, okubizwa ngokuba umzobo we-elasticity.
Ukuba isampuli ilayishwe kwakhona emva kokukhulula, umzobo wesibini woxinzelelo c ufunyenwe. Umzobo wokudumba kunye nedayagram yoxinzelelo lwesibini c yenza i-hysteresis loop phakathi kwabo. Kudongwe, i-hysteresis loops ibalulekile kwaye ngoko ke i-deformation kwindawo yokuvuvukala kunye nokunyanzeliswa kwesibini (umzobo b kunye ne-c) ayithathwa njenge-elastic, kodwa iguqulwa, kuba ayilingani nomthwalo ngokomthetho kaHooke. Ukuguqulwa kwendawo yokunyanzeliswa okuphambili (umzobo a) kwindawo apho abazange babuyele khona ngokusisigxina (akunakuguqulwa).
Imodyuli yoxinzelelo lomhlaba
Ukusuka kwidayagram yoxinzelelo olunxulumeneyo, sifumana ngokomthetho kaHooke ngokulinganayo ukuya kwimodyuli kaJung yokunwebeka E yemathiriyeli eelastiki, imodyuli yoxinzelelo lomhlaba Ms
Ms = Δσ / (Δh/h) [kp/cm2],
apho Δσ kukunyuswa komthwalo, Δh/h luxinzelelo oluhambelanayo, oluthatyathwe kwidayagram yoxinzelelo oluphambili a (fig. 2).
Imodyuli yoxinezeleko yomhlaba Ms iyahluka kwimodyuli yokunwebeka E kwemathiriyeli eelastiki, kuba Ms akatshintshi into enye kodwa iyaguquguquka kwaye inyuka ngomthwalo oqhelekileyo σ. Ngoko ke, ixabiso elinye lemodyuli yoxinezeleko Ms inokunikwa kuphela isithuba esimxinwa esinye somthwalo oqhelekileyo womhlaba Δσ. Ukuba ixabiso lemodyuli Ms liphezulu, ukunyanzeliswa komhlaba kuphantsi kwaye ngokuphambeneyo. Ngokwemigaqo yethu yesiseko, le nqobo ilandelayo yemodyuli yokucinezeleka komhlaba kwindawo yawo yendalo yamkelwe:
Ukuhlelwa okungezantsi kuthwalwa ukusuka kumbhalo wokuqala, kubandakanywa ikhefu eliphindaphindiweyo 100-400 kp/cm2. Ayikhange ihlolwe okanye ivisisane nemigaqo yangoku.
Ms = 0 - 20 kp/cm2 umhlaba ocinezeleke kakhulu
Ms = 20 - 50 kp/cm2 umhlaba ocinezeleka kakhulu
Ms = 50 - 100 kp/cm2 umhlaba ocinezelekileyo ophakathi
Ms = 100 - 400 kp/cm2 umhlaba ongacinezeleki kancinci
Ms = 100 - 400 kp/cm2 umhlaba ocinezeleke kancinci
Ms = 400 - 1000 kp/cm2 umhlaba ocinezeleke kancinci
Ms > 1000 kp/cm2 umhlaba ophantsi kakhulu ocinezelekayo.
Imodyuli yokunwebeka komhlaba
Ngendlela efanayo, sifumana imodyuli yokunwebeka komhlaba E:
E = Δσ / (Δh/h) [kp/cm2],
apho unyanzeliso loxinzelelo olunxulumeneyo Δh/h luthathwa kwidayagramu enwebekayo yomhlaba ukulungiselela unyuso oluqhelekileyo loxinzelelo oluhambelanayo Δσ.
Umhlaba oqhelekileyo odityanisiweyo nodityaniswe ngokugqithisileyo
Sl.3. Umzobo wotshintsho kwi-porosity coefficient yesampuli yomhlaba ophazamisekileyo
Ukuba senza uvavanyo lwe-oedometer ngesampuli ephazamisayo, esiyifake kwi-apparatus kwindawo yokuvunwa, kwaye sicwangcisa iziphumo zovavanyo kumzobo wenguqu kwi-porosity coefficient e kuxhomekeke kuxinzelelo σ (Fig.3) ukuhamba kodibaniso lumelwe yimizobo 1 kumthwalo wokuqala, 2 ukufumana isiqabu, 3 kumthwalo wesibini ukuya kumda wokongezwa komthwalo ongundoqo σa kunye 4 ngaphaya kwalo mda.
Umzobo wokunceda2kunye nedayagram yoxinzelelo lwesibini3yenza i-hysteresis loop ngasemva komzobo4iyaqhubeka ekwandisweni komzobo1, ngaphandle kokuqhawula, njengokungathi akukho kukhulula kunye nokulayishwa kwakhona.
Sl.4. Umzobo wokutshintsha kwe-porosity coefficient yesampuli yomhlaba ongaphazanyiswa
Nangona kunjalo, ukuba senza uvavanyo lwe-oedometer ngendlela efanayo nangaphambili ngesampuli engaphazanyiswa ethathwe kubunzulu obuthile bomhlaba (umkhiwane.4), umzobo womthwalo wesibini3izakubonisa kumthwalo omnye σb ukwaphuka kwindawo b, emva koko umzobo uzakuqhubeka4ube nethambeka eliphezulu. Oku kwaphuka kwenzeka ngenxa yokuba umhlaba apho isampuli ithathwe khona phantsi komthwalo omkhulu p=γt kunomthwalo wesampuli σ kwi-oedometer. Umthwalo ophezulu we-p usuka kubunzima bomaleko okhoyo womhlaba ongaphezulu ukuya kumphezulu womhlaba, esiwubiza ngokuba luxinzelelo lomhlaba, okanye kumthwalo womaleko ongaphambili womhlaba othathwe ngokuhamba kwexesha lukhukuliseko okanye kumhlaba we-moraine okanye umkhenkce, esiwubiza ngokuba yi-preload. Ukubonakala kokuqiniswa ngokugqithiseleyo kuyimpawu yodongwe, apho sihlula phakathi kodongwe oluqhelekileyo oludityanisiweyo kunye noluqilima.
Udongwe oluqhelekileyo oludityanisiweyo
Ngokuqhelekileyo udongwe oludityanisiweyo lukwindawo enzulu ngaphantsi komhlaba, olungazange luvezwe ngaphambili ukuba lufakwe ngaphambili. Isampulu yoludongwe, elayishwe kwi-edometer enemithwalo enkulu kunobunzima bomgangatho ophezulu “woxinzelelo lomhlaba” umaleko, ubonisa ukuhamba okuqhubekayo kokuqiniswa, ngaphandle kwekhefu kwidayagram yoxinzelelo okanye kwi-porosity coefficient change diagram. Ukuhlaliswa kolu bumba phantsi komthwalo wento kuqhelekileyo, oko kukuthi phantsi komthwalo othile, ukulungiswa kunciphisa ixesha.
Udongwe oluhlanganiswe ngokugqithisileyo
Udongwe oludityanisiweyo lukwindawo enzulu kakhulu okanye belukhe lwafakwa ngaphambili. Isampulu yoludongwe olulayishwe kwi-edometer enoxinzelelo olukhulu kunoxinzelelo lomhlaba okanye ukulayishwa kwangaphambili kubonisa ukwaphuka kwidayagram yoxinzelelo lwesalamane okanye kwi-porosity coefficient change diagram, ebizwa. igeological fracture g, kunye notshintsho olunamandla kwicala (Fig.5a). Ukuhlaliswa koludongwe phantsi kwesakhiwo kuncinci kumthwalo ongaphantsi koxinzelelo lomhlaba okanye ukulayisha kwangaphambili σ1, kodwa iba nkulu kakhulu kumthwalo ongentla σ1.
Ukuba ikhefu le-geological alichazwanga ngokucacileyo, ngoko kuchongwa ngokusebenzisa i-tangents kumzobo (Fig.5b).
Sl.5. Umzobo wotshintsho kwi-porosity coefficient yodongwe oludityanisiweyo
Umzobo wokulungisa ixesha
Lo mzobo, okwabizwa ngokuba ngumzobo wokudibanisa, ufunyanwa xa, kwinqanaba ngalinye lokulayishwa kwesampulu kwi-edometer, ixesha t kwiiyure lisetyenziswa kwi-abscissa axis, kunye nokuhlaliswa kwe-mm kwi-axis edibeneyo (Fig.6a) okanye kwi-% yentlawulo epheleleyo (Fig.6b).
Sl.6. Isazobe sokuzinziswa kwexesha
Imihlaba engabotshwanga kwaye ebotshelelweyo iziphatha ngendlela eyahlukileyo phantsi komthwalo. Imihlaba ekhululekile, efana nesanti, inemibhobho emikhulu, apho amanzi aphuma ngokukhawuleza phantsi komthwalo, ukuze umhlaba uhlale ngokukhawuleza, kunye nokuhlaliswa okukhulu okwenzeka ekuqaleni komthwalo kunye nokufikelela kwisigqibo sokugqibela kumthwalo onikiweyo ngexesha elifutshane. Imihlaba ebambeneyo efana nodongwe inemingxuma emincinci apho kunzima ukukhama amanzi phantsi komthwalo. Kukho izigaba ezibini kwinkqubo yexesha lokuhlaliswa komhlaba oxineneyo. Kwinqanaba lokuqala, ngokukhawuleza emva kokufaka umthwalo kumhlaba, ekubeni amanzi akakwazi ukugeleza ngaphandle kwama-pores, agxininisekile kwaye amkele wonke umthwalo osetyenzisiweyo. Kwinqanaba lesibini, i-pore egxininisiweyo yamanzi iqala ukukhupha phantsi koxinzelelo lwawo ngenxa yomthwalo, ngokuthe ngcembe idluliselwe kwiincinci zomhlaba eziqinileyo. Kule nqanaba lesibini, amaqhekeza ahlangana kunye kwaye i-pores iyancipha. Inkqubo ye-subsidence iyaqhubeka kuze kube yilapho ukunyanzeliswa kwamanzi kunyanzeliswa ngaphandle kweepores, oko kukuthi de kube imeko yoxinzelelo lwamanzi kwi-pores iphelile. Ngoko ke, ukuqiniswa komhlaba kuyingxaki ye-hydrodynamic, exhomekeke kwi-permeability yomhlaba kunye ne-porosity. Kwimeko yodongwe, i-permeability yayo iphantsi, inkqubo yokudibanisa inokuthatha ixesha elide kakhulu, kwaye ukongezelela, iindawo zokuhlala zingaba zikhulu kakhulu ngenxa ye-porosity ephezulu ngaphezu kwesanti. Ngesiseko sovavanyo lokudibanisa, ikhosi yexesha lokuhlalisa ingabalwa kulo lonke ixesha lokudibanisa kunye nezigaba zomntu ngamnye.