Namuhla, i-Savo Kusić igxile emafasiteleni okhuni, amafasitela okhuni-aluminium, amafasitela ngokwezifiso, umnyango kanye nezicelo zekhotheshini. Lo mbhalo uhlala uyingobo yomlando ye-geotechnical futhi awusona isithembiso sokuklama izindonga ezigcinayo, uphenyo lwe-geotechnical noma i-earthworks.

Izindlela zokunquma ukucindezela komhlaba okungenzi lutho

Ingcindezi ye-Passive Earth ibonakala kuphela esimweni lapho ukuguqulwa kodonga olubheke phansi kukhulu ngokwanele ukuze kusebenze ukumelana kwangaphakathi komhlaba, okuphikisana namandla angaphandle. U-Franzius wasungula ngokuhlolwa ukuthi ukuze uvule ukucindezela komhlaba okungenzi lutho, kuyadingeka ukususa udonga esimweni sesihlabathi esimanzi s=30_h_1,5, futhi endabeni yesihlabathi esingaphansi kwamanzi s=23h2,5lapho ukususwa s kungu-mm, futhi h kuwubude bodonga ngo-m. Ngakho-ke, uma ukuphakama kodonga kungu-h=3,0 m, ukuze kusebenze ukucindezela kwe-passive, esimweni sesihlabathi esimanzi, kuyadingeka ukuhambisa udonga ngendlela yomhlabathi s=156 mm. Kodwa-ke, njengoba ukunyakaza okukhulu kangaka kodonga akuvunyelwe ezimweni eziningi, kusingathwa ngenye yalezi zindlela ezilandelayo:

a) Uma ukuphakama kodonga kukuncane, njengoba kunjalo ngenani lesisekelo CD (isib.1a), ukucindezela komhlaba okungenzi lutho Ep akunakwa, inqobo nje uma ungqimba lwenhlabathi, oluphambi konyawo CD lungase lugujwe noma lugugulwe, futhi lubalwa kuphela ngomfutho womhlaba osebenzayo Ea kukho konke ukuphakama kodonga AB.

b) Endabeni yokuphakama kodonga oluphakeme (Fig.1b), esikhundleni sokucindezela komhlaba okungenzi lutho Ep engxenyeni yodonga CD, Ea yamukelwa njengokumelana okuphikisana namandla Ea1 kanye Ea2.

c) Endabeni yama-struts adinga ukuthola amandla amakhulu avundlile, ingcindezi egcwele ye-passive Ep iyadingeka kubo bonke ubude bodonga AB, ukuze kuqhutshwe amandla okuhlasela R (fig.1c). Uma kunjalo, inhlabathi iqala ukukhubazeka kusetshenziswa ama-jacks we-hydraulic, futhi uma inhlabathi iqukethe ubumba oluthambile noma into efanayo ekhubaza kakhulu ngaphansi komthwalo, le nto ithathelwa indawo ngobubanzi obudingekayo b nge-gravel material, i-angle yayo yokungqubuzana kwangaphakathi inkulu futhi engahlanganiswa kalula, ukuze kamuva ukukhubazeka kwenhlabathi ngaphansi komthwalo wesakhiwo kukhishwe.

Izimo zomphumela wokucindezela komhlaba okungenzi lutho ezintweni ezisekelayo, umkhiwane.158

Sl.1. Izimo zomphumela wengcindezi yomhlaba engenzi lutho

Kunezindlela eziningana zokunquma ukucindezela komhlaba okungenzi lutho, phakathi kwazo ezaziwa kakhulu izindlela ezicacile ze-Coulomb ne-Rebhann-Poncelet.

Indlela yesithombe ye-Coulomb

Ngokwale ndlela, indawo yangempela yokushelela iyamukelwa, kanye nokuthi ukumelana kwangaphakathi kwenhlabathi kuqukethe ukungqubuzana kuphela, ngaphandle kokuhlangana (c=0). Njengoba ukucindezela komhlaba okungenzi lutho kubonakala njengamandla aphikisayo, lawa i-engeli yokungqubuzana kwangaphakathi kwenhlabathi kanye ne-engeli yokuchezuka kwamandla Ep ukusuka kokujwayelekile ukuya odongeni lophawu oluphambene, okungukuthi -δ kanye -ϕ (fig.2a).

Uma indawo engaphakathi yodonga ithi AB futhi uma sisebenzisa indawo eshelelayo engafanele AC, amandla angaphandle Ep aphikiswa isisindo W seprism eslayidayo ABCA kanye nokumelana nokungqubuzana Q endaweni eshelelayo AC. Njengoba isisindo W saziwa ngobukhulu, isiqondiso nesiqondiso, kuyilapho amandla Q kanye ne-Ep aziwa ngokuqondisa nangesiqondiso, kungenzeka ukudala uhlelo lwamandla (Fig.2b), lapho kunqunywa khona ubukhulu bamandla Ep.

Uhlelo lwamandla okucindezela komhlaba okungenzi lutho ngokukaCoulomb, fig.159

Sl.2. I-Coulomb Passive Earth Pressure

Kodwa-ke, njengoba ingcindezi encane yokungenzi lutho Ep,min iyadingeka, ehambisana nendawo eshelelayo ebalulekile AC, lapho i-prism eshelelayo cishe izokheka futhi iphushwe kakhulu ngaphansi kwethonya lamandla angaphandle, kwenziwa kanje (isig.3).

Ukunqunywa okuyingcaca kwendawo eshelelayo ebalulekile kanye nokucindezela kwe- passive, fig.160

Sl.3. Ukunqunywa kwe-EP ye-passive earth pressure by Coulomb

Kudwetshiwe izindawo ezimbalwa ezislayidayo ze-AC1, AC2, AC3. . . futhi kuprism ngayinye ehambisanayo eshelelayo inqume isisindo W1 = _AΔABC1_x1,00x γ, W2 = _AΔABC2_x1,00x γ, W3 = AΔABC3 x1,00x γ. Bese, ku-prism ngayinye, uhlelo oluhambisanayo lwamandla luyakhiwa futhi amandla EP ayanqunywa.1, EP2, EP3… Lawa mandla asetshenziswa ngesilinganiso esikahle kumdwebo wamandla EP futhi i-tangent yalo mdwebo ngokuhambisana ne-abscissa eksisi inikeza inani elincane kakhulu Ep, elihambisana nendawo eshelelayo ebalulekile AC. Ububi bale ndlela ukuthi, ngenxa yesisombululo sayo sesithombe, inganikeza amandla Ep achezuka kakhulu eqinisweni. Ngakho-ke, le ndlela ayivamile ukusetshenziswa.

Indlela yesithombe kaCulmann

Ngokwale ndlela, kucatshangwa ukuthi ukucindezela komhlaba okungenzi lutho Ep kusebenza nge-engeli -δ nokujwayelekile ukuya odongeni olusekelayo, ukuthi umugqa womthambeka wemvelo wenhlabathi weqa i-engeli -ϕ nendawo evundlile, nokuthi umugqa wokuma weqa i-engeli -(δ+ϕ) nomugqa wodonga (Fig.4a). Esimeni sokulinganiswa komkhawulo amandla amathathu abambayo W, Q kanye no-Ep ayaphambana endaweni eyodwa. Njengoba amandla W aziwa ngokuqondisa kwawo, ubukhulu kanye nesiqondiso, kanye namandla Q kanye ne-Ep ngokuqondiswa kwawo kanye nesiqondiso, singadweba uhlelo lwamandla (isig.4b). Uma sijika lonxantathu wamandla90°- ϕ ohlangothini oluphambene newashi, amandla W azowela aqonde kulayini wemithambeka yemvelo yomhlabathi AN, amandla Q aqonde endaweni eshelelayo AC, namandla Ea aqonde kumugqa wesikhundla BH, njengoba phakathi kwamandla W kukhona i-engeli _Q_α, kuyilapho phakathi kwamabutho W kanye ne-_Q_α futhi evamile odongeni kukhona i-engeli δ, ngakho isiqondiso samandla Ep siqondana nesiqondiso somugqa wendawo BH (fig.4a).

Icebo likaCulmann lamandla nemigqa yezingcindezi zomhlaba ezingenzi lutho, isig.161

Sl.4. Ukunqunywa kokucindezela komhlaba okungenzi lutho ngeCoulomb

Inqubo yokunquma ingcindezi yomhlaba engenzi lutho imi kanje (Fig. 4c). Kusukela emlenzeni wodonga A sidweba izindawo ezimbalwa ezislayidayo ezinganasizathu AC1, AC2, AC3…. Indawo ngayinye kulezi ihambisana neprism eshelelayo ABC1, ABC2, ABC3…, ubude bayo obuhambisana nokusalungiswa sicabanga ukuthi bulingana nobunye. Uma izisindo zalawa maprism obumba W1 = _AΔABC1_x1,00x γ, W2 = _AΔABC2_x1,00x γ, W3 = _AΔABC3_x1,00x γ, lapho γ kuyisisindo se-volumetric senhlabathi, esetshenziswe emgqeni we-slope yemvelo yomhlabathi AN, sizothola amaphuzu I, II, III… Ngokudweba imigqa ehambisana nomugqa wesikhundla kusuka kulawa maphuzu, sithola amaphuzu okuhlangana R1, R2, _R3… Onxantathu A_I_R1, A_II_R2, A_III_R3 yizindiza ezinamandla W, Q kanye ne-Ep yezindawo ezishelelayo ezilandelanayo. Ngokuxhuma amaphuzu R1, R2, R3… sithola umugqa kaCullmann wezingcindezi zomhlaba ezingenzi lutho, lokho okubizwa nge-Cullmann’s Ep Line. I-tangent kulo mugqa ngokuhambisana nomugqa wokuthambeka kwemvelo komhlaba inikeza ubude obuncane KK’, okuthi ngokulingana namandla W kunikeza ukucindezela komhlaba okungenzi lutho Ep.

Uma sinweba isiqondiso AK esimpambanweni yomgwaqo ngomugqa wezwe, sithola indawo eslayidayo enokumelana okuncane AC.

Indlela ye-Rebhann-Poncelet

Ngokwale ndlela, inqubo iyafana naleyo yokunquma ingcindezi yomhlaba esebenzayo umehluko wokuthi amandla Q asebenza nge-engeli -ϕ ngokujwayelekile endaweni eshelelayo, kanye namandla Ep nge-engeli -δ ngokujwayelekile ukuya emgqeni wodonga. NgokukaRebhann, AΔABC = AΔACD (isig.5a). Inqubo yokunquma i-passive earth pressure imi kanje:

Ukwakhiwa kwesithombe sokucindezela komhlaba okungenzi lutho ngokusho kukaRebhann-Poncelet, fig.162

Sl.5. Ukunqunywa kwengcindezi yomhlaba engenzi lutho ngokusho kukaRebhann-Poncelet

Kusukela phansi odongeni A sidweba umugqa wokuthambeka kwemvelo kwenhlabathi nge-engeli -ϕ enezingqimba.

Kusukela phezulu odongeni B sidweba umugqa wendawo BH nge-engeli -(δ+ϕ). Ephuzwini elithi M empambanweni yendawo nendawo emthambekeni wemvelo womugqa ophansi, okuvamile kuphakanyiswe empambanweni L ngesemicikilini engaphezu kuka-AN njengobubanzi.

Ngokuvula ikhampasi AL, sidlulisela iphuzu L ku-D (AL=AD).

Ngokudweba ukusuka ephuzwini D elihambisana nomugqa wokuma kuya ezimpambanweni zomgwaqo C ngomugqa wendawo, sithola uhlangothi olulodwa lonxantathu wokucindezela komhlaba DC = e. Sidlulisela iphoyinti C ku-F (DC= DF) futhi sehlise i-CK evamile emgqeni wemvelo wenhlabathi, sithola unxantathu wokucindezela komhlaba DCF, lapho sithola khona i-Ep=1/2_γ_ ef, lapho γ kuwukuminyana kwenqwaba yomhlabathi.

Ulayini AC umele indawo eslayidayo. Umdwebo we-passive earth pressure diagram uthi ba (Fig.5b). Itholakala ngesisekelo sefomu

Ep = xh/2, lapho x =2_Isiqephu_/h

Indawo yokuhlasela yamandla Ep isendaweni ephakeme emaphakathi namandla adonsela phansi kanxantathu abc. Amandla Ep asebenza nge-engeli -δ ngokujwayelekile odongeni olubambayo.

Izindlela ezishiwo, amayunithi, amafomula kanye namanani adluliswa esuka kumthombo womlando futhi awathatheli indawo yocwaningo lwe-geotechnical, ukubala okumile, iphrojekthi yodonga olugcinayo noma uhlelo lokuqalisa. Amathuba okuhlanganisa ukumelana nokuzamazama ancike ekuguquguqukeni okuvunyelwe, imingcele yangempela kanye nokwendlaleka komhlabathi, amanzi angaphansi komhlaba nangaphezulu, imisele, imithwalo eyengeziwe, imithelela yokuzamazama komhlaba, ukuguguleka komhlabathi, ukumba, izigaba zokwakha kanye nezakhiwo ezingomakhelwane. Isixazululo sendawo ethile kufanele sinqunywe ucwaningo olufanele kanye nochwepheshe abagunyaziwe be-geotechnical nezokwakha ngokuvumelana nemithetho yamanje.