Kana tikacheka silinda muvhu rakasungwa ndokuisa pasi pekuita kwekudzvanywa kwakajairwa P (fig. 1), mutsilinda muchabuda kushushikana kutsva, kureva kushushikana kwekudzvanywa kwakachinjika σ uye kushushikana kwekucheka kwakachinjika. Kana tikawedzera zvishoma nezvishoma kudzvanywa P, pashure penguva yakati pachaonekwa mitswe yakatsveyama pasilinda, uye pakarepo mushure mezvo silinda ichatsemuka. Panguva yekutsemuka silinda yave yakatsvetwa pasi pekudzvanywa P uye pamusoro pendege yekucheka ine kushora kushoma N-N.
Fig. 1. Mhedzisiro yekudzvinyirira painderi yakabviswa muvhu rinobatana
Kupikisa kwevhu kwakapihwa nechitubu pakupikisa simba P panguva yekutyoka kunonzi kupikisa kwekuveurwa kwevhu, uye kona α yekurereka kwechikamu chekupikisa kuduku zvikuru ichienzaniswa nehoriyontari inonzi kona yedunhu rekupikisa kuduku zvikuru kwekuveurwa kwevhu.
Kudzivirira kwekutsvedza kwevhu rakasungwa kunoumbwa nezvinhu zviviri zvekudzivirira zvemuzvarirwo: kukweshera kwemukati pakati pezvimedu zvakasimba uye kubatana kunobatanidza zvimedu zvakasimba. Simba rekutsvedza revhu rinotorwa rakaenzana nekushushikana kukuru kwekutsvedza panguva yekutyoka uye rinoratidzwa neequation
τf = c + σ tg_φ_
apo: τf simba rekushevedzana kwevhu [kp/cm2],
c kuwirirana kwevhu [kp/cm3],
σ kumanikidzwa kwevhu kwakajairika [kp/cm3],
φ kona yekukweshera kwemukati kwevhu.
Muenzaniso uri pamusoro wakapihwa nemuFrance Coulomb muna 1785. maererano. Maererano nemuenzaniso uyu, kune ivhu rakapiwa kubatana c kunogara kwakafanana uye hakunei nekumanikidzwa kwakajairika, nepo kupikisa kwekukweshera σ tg_ϕ_ kuchienderana chaizvo zvakananga nekushushikana σ. Muchokwadi kubatana e hakusi kugara kwakafanana kune ivhu rakapiwa, asiwo kune imwe nhanho kunoenderana nekushushikana kwakajairika σ, nokuti pasi pemhedzisiro yekumanikidzwa uku ukobvu hwefirimu remvura rinofukidza zvikamu zvakasimba hunoderera uye nokudaro kubatana kunowedzera. Muenzaniso waCoulomb unoshanda kune ivhu rinopindika, mairi pasi pekumanikidzwa kwakajairika mvura iri mumaporesi inosvinwa kunze isina kupikiswa, izvo zvinoitika muivhu rematombo neguruva rejecha, asi hazvisi izvo zveivhu rakasungirirwa, iro risingapindiki zvikuru, nokudaro mvura iri mumaporesi inosvinwa kunze zvakaoma uye inoramba iripo semvura yeporesi yakamanikidzwa pasi pemutoro P.
Kushushikana kunobudirira uye kusina kwaakarerekera muvhu
Muf. 2. Kushushikana kunoshanda uye kusiri kwechokwadi muvhu
Kana tikaisa muenzaniso wevhu pasi pemudziyo, somuenzaniso jecha rakaoma, uye tikarirova nemutoro upi noupi, semuenzaniso mapfuti emutobvu ane huremu W, mutoro wose weuremu uhwu unotakurwa nezvimedu zvakasimba zvevhu. Kudzvinyirira kwakatarwa pamusoro pamuenzaniso p0 = W/A mu kp/cm3, apo A iri nzvimbo yekuyambuka muenzaniso, kunokonzera kugara pasi pamuenzaniso, kureva kuderera kweporosity yawo, asi kunozokonzera zvakare shanduko dzezvimwe zvimiro zvepanyama zvemuenzaniso zvakadai sekukwira kwesimba rekusheura, kukwira kwemodulus yekumanikidzwa uye zvimwe. Kudzvinyirira kunowanikwa panzvimbo dzekubata pakati pezvimedu kunonzi kudzvinyirira kunoshanda kana intergranular pressure σ’. Kana kusimbiswa kwasvikwa, kureva kana muenzaniso wamira kugara pasi pasi pemutoro p0, kudzvinyirira kunoshanda kunoenzana nekudzvinyirira kwakazara kwakatarwa kunowanikwa pakudzika uko ivhu riri kuongororwa. Panguva iyi pakudzika, pasi pechiso chemuenzaniso pamuf. 2 σ’ = W/A + hzγ apo γ iri huremu hwemuenzaniso pahuwandu hwawo.
Asi kana tikaremedza muenzaniso uri mumudziyo nemvura kusvika pahurefu h, mvura iyi yazadza maporesi ese emuenzaniso, kudzvinyirirwa kwechitsvimbo chemvura pamusoro pemuenzaniso hγw, uko γw kurema kwevhoriyamu kwemvura, hakuzokonzere kugara pasi kwemuenzaniso nekuderedzwa kweporosity yayo uye hakuzowedzeri simba rayo rekutsvedzerera kana modulus yekutsikiririka. Nokudaro, kudzvinyirirwa kwehydrostatic hγw kunonzi kudzvinyirirwa kusiri kwechero chinhu. Kudzvinyirirwa kusiri kwechero chinhu kunoshandiswa nechiratidzo u kunotapuriranwa nemuenzaniso kumativi ese nesimba rakaenzana. Kudzvinyirirwa uku hakuzokonzere kuwedzera kwesimba rekutsvedzerera, nekuti mvura yacho pachayo haina simba rekutsvedzerera.
Saka kumanikidzwa kunoshanda σ’ kunofambiswa kuburikidza nenzvimbo dzekubata pakati pezvidimbu zvakasimba zvevhu, uye kumanikidzwa kusina kwaakarerekera u kunofambiswa kuburikidza nemvura iri mumapore. Kana chikamu chezasi chechirongo chakazadzwa nemuenzaniso wevhu wakazara, une uremu hwevhoriyamu γz, uye pamusoro pemuenzaniso kusvika padanho N chirongo chizere nemvura ine uremu hwevhoriyamu γw, ipapo kumanikidzwa kwese σ pane chero poindi yemuenzaniso kuchava σ = σ’ + u.
Pakudzika hz, pasi pechiso chemuenzaniso, pressure inoshanda ichava σ = σ’ - u
apo σ = h γw + h γz
u = (h + hz) γw.
Naizvozvo zvichava σ’ = hz γ’
γ’ ihuremu hwesubmerged soil mumvura.
Equation yakajairika yesimba rekukwenyana kwevhu
Kana ivhu rakasungwa tikariremedza nemutoro P, mutoro uyu unokonzeresa kugara pasi kwevhu uye pakutanga pasi pechiito chawo mweya unobviswa kubva mumaburi, zvekuti munguva pfupi mumaburi munongosara mvura. Nekuti ivhu rakasungwa harina kupfuurisa mvura zvakanaka, mvura haibvi pakarepo, saka inoramba iri semvura yakamanikidzwa mumaburi uye pakutanga inotakura mutoro wekunze wose P. Pakufamba kwenguva, pasi pechiito chemutoro P mvura inotanga kusundwa ichibuda mumaburi uye zvimedu zvakasimba zvinotanga kuswedera pedyo, izvo zvino zvinochengeta chikamu chemutoro P. Ipapo tine τf =c + (σ - u) tg_ϕ,_ apo σ ndiko kudzvanywa kwese kunobva pamutoro P, u ndiko kudzvanywa kwemvura mumaburi.
Kudzvinyirirwa kwemvura yemuma pore mu u kunoenderana nezvinhu zvakawanda, zvakaita senguva yekubatanidzwa, kupindika kwevhu, ukuru hwemutoro uri pavhu nezvimwe. Simba rekugera revhu rinoenderana nekudzvinyirirwa kwemvura yemuma pore uye rinenge rakakura kwazvo pa u=0, apo kubatanidzwa kwevhu kunoitika.
Kushanda kwecolloid kwevhu
Zvinhu zvekusamira kwemukati kwevhu kuwirirana uye kukweshana zvinogona kusiyana uye zvikuru zvinoenderana nehukuru hwezvimedu zvakasimba zvevhu uye hunhu hwazvo hweplastiki. Nechinangwa chekutsanangura kukanganisa kwekuwirirana zvichienzaniswa nekusamira kwemukati kukweshana kwevhu rinobatana, Skempton akaunza pfungwa yekushanda kwekoloidal kwevhu _K_P, iyo inomiririrwa nehukama hweindekisi yeplastiki IP nehuwandu hwezvimedu zviduku kudarika 0,002 mm mu % yehuremu hwese hwemass. Panguva iyoyo pakagamuchirwa chiyero chinotevera (sl. 3):
Muf. 3. Kushanda kwecolloid kwevhu
Kune KP < 0,75 ivhu risina kuita,
kune KP = 0,75 – 1,25 ivhu rakajairika,
zve Kp > 1,25 yevhu rine basa.
Kana KP ichiwedzera, pesvedzero yekunamatira inowedzera zvichienzaniswa nekukweshera kwemukati kwevhu rinobatana.
Kunzwa kwetsvina
Kana tikabvisa muvhiri wehumburumbira muivhu rine kubatana, dhayamita 3—3,4 cm uye kureba ~ 5 cm tikauisa pasi pemutoro wakatarisana, panguva yekuputsika kwehumburumbira tichawana simba rekumanikidza revhu riri mune risina kukanganiswa mamiriro σ__ₙ:
σn = P/A mu kp/cm2,
apo A iri chikamu chemuchinjikwa chesilinda.
Mushure mokupedzwa kwekuedzwa, sampuli yakatyoka tinoiisa parutivi uye tinozogadzira zvakare silinda yemasaizi mamwe chete, tichishandisa silinda-mould imwe chete, kuti hunyoro hwayo hurambe hwakafanana nehwaive pakuedzwa kwekutanga. Zvadaro, pakarepo mushure mekugadzirwa kwesilinda yakasanganiswa, kuedzwa kunodzokororwa pairi, kuitira kuti kuwanikwe simba rekudzvinyirira revhu riri mumamiriro akavhiringidzwa σ__ₚ.
Kusagadzikana (sensitivitet) S__ₜ ndicho chiyero chesimba rekudzvanywa muchimiro chisina kukanganiswa kuenda kusimba rekudzvanywa muchimiro chakanganiswa: St = σn/σp,
Maererano nechimwe chiyero, kunzwa S__ₜ kunoongororwa seizvi:
- zve S__ₜ = 1 — 2 kusagadzikana kweivhu kwakaderera,
- kune S__ₜ = 2 — 4 pane kunzwa kwepakati kwevhu revhu,
- kune S__ₜ = 4 — 8 kunoratidza kunzwa kukuru kwevhu revhu,
- kuna S__ₜ > 8 ivhu rinonyanyonzwa.
Muzvisikwa zvinoitika kuti nekuda kwechiito chemagetsi, semuenzaniso kudengenyeka, ivhu revhu rinongoerekana rarasa kusimba kwaro, iro richizozodzoka kana rarara. Ichi chivakwa chinonzi tiksotropija yevhu. Mazhinji mavhu ane zvimwe zvivakwa zvetiksotropiki. Mienzaniso yekutsvedza kwemateru emigero nekuda kwekubuda kwevhu retiksotropiki inozivikanwa muNorway, Sweden neFinland, uko nekuongorora kwakawanikwa kuti pakanga pasina kuchinja kwehunyoro hwevhu panguva iyi, kureva kuti hunyoro hwevhu hwaive hwakafanana pamberi uye pashure pekubuda.