Phantsi kwempembelelo yomthwalo, wonke umhlaba, ngaphandle kwelitye eliqinileyo, uyazinza. Ukuzinza ngokubanzi kuvela kwizizathu ezibini: ukuxinana komhlaba oko kukuthi ukuncipha komthamo wawo ngenxa yokugxothwa komoya okanye amanzi emingxunyeni yawo, kunye nokunyanzeliswa kwicala lomhlaba ecaleni kwemiphetho yesiseko ngenxa yokutyibilika kwamasuntswana aqinileyo omhlaba.
Ukuthoba komhlaba ngenxa yokuxinana kuquka ukuguquka okuse-elastic nokwe-plastic, okubangelwa ngumthwalo wesiseko, apho xa umthwalo ususwa umhlaba ubuyela ngokuyinxenye kwimeko yawo yokuqala.
Ukuzinza ngenxa yokutyhalwa ecaleni komhlaba kuquka kuphela ukuguquka kweplastiki, apho ekukhululweni umhlaba ungabuyeli kwimeko yawo yangaphambili. Oku kuvela rhoqo kakhulu kwiziseko ezincinci ezenziwe kubunzulu obuncinane ngaphantsi komhlaba. Ngokunjalo, ukutyhalwa komhlaba ecaleni kwenzeka nakumhlaba onomswakama kakhulu nowune-engile encinane yokukhuhlana kwangaphakathi.
Njengoko umthwalo ovumelekileyo womhlaba uthathwa kwindawo yeenguqu ezilastiki-neplastiki, ukubalwa kokuhlala kwenziwa kuphela ngokusekelwe ekuncipheni kwesithuba esingenanto somhlaba phantsi komthwalo, apho ukushiywa kungahoywanga kokuhlala okubangelwa kukukhutshelwa ecaleni komhlaba, okuqwalaselwa njengokungabalulekanga.
Ukuhlala phantsi ngenxa yokuxinana kuxhomekeke kukungena kwamanzi emhlabeni, kuba kwenzeka ngenxa yeepore, ezisemhlabeni wendalo zihlala zigcwele amanzi kancinane okanye kakhulu. Ngoko ke, ukuhlala phantsi komthwalo emhlabeni eneneni yinto ye-hydrodynamic, kuba inkqubo yokuhlala phantsi ixhomekeke kwisantya sokukhutshwa kwamanzi kwiipore, apho ukungena kwamanzi emhlabeni kudlala indima enkulu.
Imihlaba engadityaniswanga njengegrabile nesanti inee pores ezinkulu, ngenxa yoko ukungavimbi kwayo kukhulu kwaye amanzi asezintubeni aphantsi komthwalo weziseko akhawuleza akhutshwe. Ngenxa yoko, kwimihlaba engadityaniswanga ukuhlala phantsi komthwalo weziseko kwenzeka ngokukhawuleza, ngokuqhelekileyo sele ngexesha lokwakha okanye kungekudala emva koko. Ngenxa yoko, ukuhlala phantsi kweziseko kumhlaba ongadityaniswanga kunqabile ukubalwa.
Imihlaba edityanisiweyo inee-pores ezincinci, ukungena kwayo kuluncedo kuncinane yaye ukukhutshwa kwamanzi avela kwi-pores phantsi komthwalo wesiseko kunokuhlala ixesha elide kakhulu, kwezinye ii-clay ezinamasuntswana amancinci kude kube ngamashumi eminyaka. Ngaphandle koko, kuba i-porosity iyonke yomhlaba odityanisiweyo inkulu kakhulu kunaleyo yomhlaba ongaqiniswanga, ukuhlala phantsi komhlaba odityanisiweyo kukhulu kakhulu.
Kumhlaba odibeneyo, apho iipore zawo zizaliswe ngokuyinxenye ngumoya kwaye ngokuyinxenye ngamanzi, kuqala kuvela ukuhlala phantsi ngenxa yokuxinana komoya kwiipore, ngelixa umxholo wamanzi uhlala ungatshintshanga, emva koko kuvelise ukuhlala phantsi ngenxa yokukhutshwa kwamanzi kwiipore. Kumthwalo ongaguqukiyo womhlaba ngenxa yempembelelo yobunzima kunye nomthwalo oluncedo wesiseko, kuvela zombini ezi ntlobo zokuhlala phantsi, kodwa inkqubo yexesha lokuhlala phantsi iyahluka.
Kukho nezinye izizathu ezibangela ukuzinza komhlaba, ezifana nokwehla okusisigxina kwinqanaba lamanzi angaphantsi komhlaba, utshintsho lwekhemikhali ekwakhekeni komhlaba kunye nezinye iziphazamiso emhlabeni.
Uphononongo lokuhlala phantsi komhlaba luquka ukubala kwangaphambili kokuhlala phantsi, okwenziwa ngokusekelwe kuvavanyo lwaselabhoratri lweesampuli zomhlaba kunye nokubeka iliso ekuhlaleni phantsi, okwenziwa ngexesha lokwakhiwa kwesakhiwo nangexesha elithile emva koko.
Ukubalwa kokuhlalisa xa isiseko silayishwa embindini
Makhe siqwalasele isihlangu sesiseko esisekwe emhlabeni owenziwe ngamaleko ahlukeneyo amaninzi, umzekelo umaleko wesanti H0, oko kukuthi H1 phantsi kwesihlangu, umaleko womhlaba wodongwe onobukhulu H2, umaleko wodongwe olunesuntswana esincinane onobukhulu H3, phantsi kwawo kukho igrabile exineneyo enomaleko omkhulu, kunye nenqanaba lamanzi angaphantsi komhlaba NPV (umz. 1a).
Kuba kubalwe ukwehla komhlaba kufuneka kufakwe umzobo woxinzelelo ngenxa yobunzima bomhlaba ngokwawo (umzobo wasekhohlo kumzobo 1b) kunye nomzobo woxinzelelo ngenxa yempembelelo yomthwalo owongezelelweyo osuka kwisiseko (umzobo wasekunene kumzobo 1b). Umzobo woxinzelelo ngenxa yobunzima bomhlaba ngokwawo sifumana kubukhulu bemigangatho Σ_H_ kunye nobunzima bawo ngomthamo γ. Ukuba ubunzima besanti ngomthamo γ1, isanti engaphantsi kwamanzi γ’1, umhlaba onodongwe ongaphantsi kwamanzi γ’2, udongwe olungaphantsi kwamanzi γ’3, iingcinezelo zoxinzelelo emhlabeni ngenxa yobunzima bomhlaba ngokwawo ziya kuba (sl. 1)
γ1 · H’; γ’1 · H’’; γ’2 · H2; γ’3 · H3;
Ishadi loxinzelelo ngenxa yesenzo somthwalo silifumana ngokubala usebenzisa enye yeendlela ezaziwayo, umzekelo ngokukaSteinbrenner okanye uNewmark, kubunzulu obahlukeneyo phantsi kwesiseko.
Ukuba sichaza ngo P umthwalo wesiseko, ngo A indawo yaso ethe nca emhlabeni, ngo γ1 ubunzima bevolyum yomhlaba kubunzulu bokusekwa t ngezantsi komphezulu womhlaba, umthwalo othile wesiseko ngu P/A ngoxa ubunzima bomhlaba obusuka kuwo kwelo kubunzulu linye ngu γ1t. Ukuze kufumaneke umthwalo owongezelelweyo womhlaba ngenxa yomthwalo wesiseko, kufuneka kususwe uxinzelelo lobunzima bomhlaba γ1t kumthwalo wesiseko P/A, ukuze umthwalo owongezelelweyo womhlaba ube
p0 = P/A – γ1t.
Kobunzulu obufanayo t sisebenza kwakhona uxinzelelo γ1t ngenxa yobunzima bomhlaba bawo, ngoko kobu bunzulu kusebenze uxinzelelo olupheleleyo (P/A – γ1t) + γ1t, apho ukuhlanganiswa komhlaba phantsi koxinzelelo γ1t kwenziwe ngaphambi kokwakhiwa kweso sakhiwo.
Sl. 1. Ibalo lokuhlala phantsi komthwalo osembindini wesiseko
Nangona kunjalo, ukuba inxalenye ethile yesiseko engaphezulu kwenyawo lesiseko igcwaliswa ngomhlaba (sl. 1c), kufuneka kuthathelwe ingqalelo umthwalo womhlaba ogalelweyo 2_Q_, ukuze kule meko umthwalo owongezelelweyo ube
_P+2_Q/A – γ1t.
Kwisisele sesiseko esimise okweribhoni kukho A = b x 1,0 m kwi 1 m’ yesiseko.
Ukubalwa kokuzinza kwenziwa kuzo zonke iimaleko zomhlaba ocinezelwayo ukuya kubunzulu befuthe lomthwalo wesiseko. Ngaphambili kwakucingwa njengomda wefuthe lomthwalo wesakhiwo ubunzulu apho zikhona iisingqisho zokuqina ≥ 10% p0. Namhlanje kwamkelwa ukuba lo mda usebunzulu apho uxinzelelo olusuka kumthwalo wongezelelweyo pz lulingana no 20% woxinzelelo olusuka kubunzima bomhlaba ngokwawo: pz = 0,2 ·γ_Σ_H. Ngaphantsi kwalo bunzulu ukuzinza akubalwa. Ngokwenye imithetho kubhengezwa ukubalwa kokuzinza kweemaleko ukuya kubunzulu 2_b_ ukuya ku 3_b_, apho b bububanzi besiseko. Ukuba ekugqibeleni kukho umaleko wegrabile njengakumz. 1a, awuthathelwa ngqalelo ekubalweni kokuzinza, kuba ukuzinza kwawo phantsi komthwalo wesiseko kuncinci kakhulu kwaye kwenzeka ngexesha lokwakha.
Kobunzulu z phantsi kwesiseko somthwalo kukho uxinzelelo lokucinezela pg ngenxa yobunzima besiqu somhlaba (umz. 1b), ngelixa impembelelo yonyuso lokuphakama nayo ithathelwe ingqalelo. Kolu xinzelelo lokuqala lokucinezela kongezwa uxinzelelo pz ngenxa yempembelelo yomthwalo wesakhiwo kuloo bunzulu bunye. Ngoko ke, nakweyiphi na indawo M kubunzulu z phantsi kwesiseko somthwalo kulawula uxinzelelo olupheleleyo lokucinezela pn = pg + pz.
Phantsi kwesenzo somthwalo owongezelelweyo, umhlaba uhlala phantsi kwaye ude ufumane ukuguquka kwicala. Ukuba ukuguquka kwicala kungahoywa, kuba kuncinci ngokuthelekiswa, ekubeni umthwalo ovumelekileyo womhlaba ukwindawo yotshintsho oluyi-elastic-plastic, kunokwamkelwa ukuba ubalo lokuhlala lwenziwa ngokusekelwe kuvavanyo lokucudeka kwi-edometer, ngesampulu engaphazamisekanga ethe yakhutshwa kummandla wenqaku elijongiweyo emhlabeni, apho kugqitywa khona imodyuli yokucudeka komhlaba Ms.
Ngokusekelwe kumthetho kaHooke sine
Δ_s_ = pz/Ms,
apho u Δ_s_ ukwehla okukhethekileyo, ngexesha leyunithi lobukhulu bomaleko, pz uxinzelelo kubunzulu bomhlaba z ngenxa yomthwalo owongezelelweyo.
Ukuba sithatha ukuba ubukhulu bomaleko dz buncinane ngokwaneleyo ukuze pz ne Ms zamkelwe njengezizinzileyo, ukulungela ukuhlala okusisiseko kuya kuba
Δ_s dz_ = pz/Ms dz.
Ukuzinza ngokupheleleyo komaleko onebukhulu H kuya kuba
Ukuba pZ kunye MS zihlala zingaguquki kumaleko onobukhulu H, kuya kuba
s = pz/Ms · H.
Eneneni pz no Ms abazizinzanga kumaleko wobukhulu H1, kodwa kuthathwa ixabiso labo eliphakathi kwindawo M.
Imodyuli yokucinezeleka komhlaba Ms imiselwa ngeendlela zelabhoretri kumaleko ngamnye ngokwahlukeneyo. Kumhlaba oqhele ukucinezeleka kakuhle, imodyuli Ms imiselwa kwidayagramu yoxinzelelo lokuqala, apho umthwalo opheleleyo σ2 = pg + pz; σ1 = pg = Σ_γt,_ umthwalo owongezelelweyo Δ_σ_ = σ2 – σ1 = (pg + pz) – pg, yaye amaxabiso ahambelanayo oxinzelelo olulinganiselweyo ngu Δ_h2_/h no Δ_h1_/h, ngoko ke
Nangona kunjalo, ukuba kungudongwe oluphinde lanyanzeliswa ngaphambili, imodyuli yokucinezeleka imiselwa kumzobo woxinzelelo lwesibini. Kumzekelo kwi sl. 2 sinayo:
Umz. 2. Ukumisela imodyuli yokucinezeleka komhlaba ngokusekelwe kwidayagram yokuxinana okunxulumeneyo
Koku kungentla kulandela ukuba ukuhlala phantsi kodongwe olukhululwe ngaphambili kuya kuba kuncinci kakhulu kunokuhlala phantsi komhlaba oqinisiweyo ngokwesiqhelo.
Impembelelo yokuqina kwesiseko ekuhlaleni
Nangona enyanisweni zingekho iziseko eziguquguquka ngokupheleleyo, apho ukuhlala kwendawo enye kungaxhomekekanga ekuhlaleni kwendawo ekufutshane, ekubalweni kokuhlala kwahlulwa iziseko ezithambileyo kunye neziseko eziqinileyo.
Iziseko eziguquguqukayo, ekuqondwa ngazo iinqwelo zamatye kunye neenduli, phantsi komthwalo ofanayo zivelisa kwiindawo ezithile iiseti ezahlukeneyo zokuhlala. Ngenxa yoko, kwezi ziseko ukubalwa kokuhlala akwenziwa kuwo wonke ummandla olayishiweyo, kodwa kwiindawo zawo nganye nganye: iindawo zeekona A, B, C no D, iindawo eziphakathi kwamacala E, F, H no J kunye nendawo esembindini G yomphezulu woxande (sl. 3). Phantsi komthwalo ofanayo ukuhlala kweendawo B, C no D kuyafana nendawo A, ukuhlala kwendawo, H kuyafana nendawo E, indawo J ifana nendawo F kumhlaba ofanayo ngobume.
Umz. 3. Ukubalwa kokuhlala phantsi kweendawo ezithile zomphezulu olayishiweyo
Ukubala ukuhlala phantsi komqokozo phantsi kwendawo ethile G enomthwalo, i-rekhthangile ABCD yahlulwa ibe ziirekhthangile ezine ezincinane, yaye ukuhlala phantsi G kufumaneka njengendidi yezithambiso ezibangelwa yirekhthangile nganye eyahluliweyo.
Iziseko eziqinileyo azihlali phantsi ngendlela efanayo nezo ziguqukayo, kuba kuzo akunakwenzeka ukuba iindawo ngazinye zihlale phantsi. Ngoko ke ukuhlala phantsi kweziseko eziqinileyo kubalwa njengento epheleleyo, kanti ngokwenqanaba lokuqina kubalwa ixabiso eliphakathi lokuhlala phantsi ngendlela eyahlukileyo, kuba ukusasazeka koxinzelelo ezantsi kwesiseko kuxhomekeke ekubeni isiseko siqinile kangakanani.
Kwiingxowa eziqinileyo ezimile njengekwadrati okanye uxande oluncinane, apho a < 2_b_, kubalwa ukuzinza sG kwindawo esembindini G kwaye kwamkelwa ukuzinza ngokubanzi kwesiseko s = 3/4 sG. Kwiingxowa eziqinileyo ezimile njengoxande olude okanye umtya kubalwa ukuzinza kwendawo yokuphela E, indawo esembindini G nendawo M esembindini womgama phakathi kwazo, ecaleni kwe-asi ende yesiseko, ize ithathwe ixabiso eliphakathi.
UVan Hamme ucinga ukuba ukubalwa ngokuchaneka ngakumbi kokuhlala phantsi kwe-“ndawo ephawu P”, ethi ukusuka kwiiasi eziphakathi ibe kumgama
ezivela kwiiasi eziphakathi. NgokukaVan Hamme, ukuzinza kweendawo ezithile ezithile zesiseko akuxhomekekanga kwindlela yokusasazwa koxinzelelo emazantsi esiseko. Kwezi ndawo ukuzinza kunokubalwa kusetyenziswa ingcinga yokuba ukusasazwa koxinzelelo emazantsi esiseko kufanayo. Kwisihlangu sesiseko esiqinileyo, esilayishwe ngomthwalo ofanayo apho ukusasazwa koxinzelelo emazantsi esiseko kungalingani kwaye kunyuka ukuya emiphethweni yesihlangu, nangona kunjalo ukuzinza kwesiseko kuyalingana nokuzinza kwendawo ebonakalayo P. Iingcinezelo kubunzulu z phantsi kwendawo ebonakalayo P yommandla oxande onobude a, ububanzi b, olayishwe ngomthwalo ofanayo p0 zinokubalwa kusetyenziswa itafile 1 eyenziwe nguJelinek.
Uxinzelelo σzP kubunzulu z phantsi kwendawo ephawulweyo P luyi σzP = (σz/p0)·p0, apho p0 ngumthwalo owongezelelekileyo womhlaba.
Itheyibhile 1. Amaxabiso σz/p ezixinzelelo eziphantsi kwendawo yeempawu P ngokuxhomekeke kumlinganiselo wobunzulu z ukuya kububanzi b nakuwo umlinganiselo wobude a ukuya kububanzi b besiseko somqamelo
Ukubalwa kokuhlala kusetyenziswa utshintsho lwe-coefficient yesithuba esingenanto somhlaba
Ukuba sityumba ngo e0 i-coefficient yesithuba esingenanto sesampuli engaphazamisekanga ekhutshwe kumaleko womhlaba, kwaye ngo ei i-coefficient yesithuba esingenanto yesampuli efanayo emva kokugqitywa kokudityaniswa kwi-edometer phantsi komthwalo σ1 (sl. 4a), ukuncipha komthamo wokuqala womhlaba phantsi kwesenzo somthwalo Δ_σ_ kuhambelana nokuncipha kwesithuba esingenanto, oko kukuthi ne-coefficient yesithuba esingenanto somhlaba
Δ_e_ = e0 – e1
Sl. 4. Ukubalwa kokuhlala komhlaba kusetyenziswa utshintsho lwe-coefficient yesithuba esingenanto somhlaba
Umthamo wokuqala wesampulu yomhlaba ngu
Ukuhlalisa okuthe ngqo Δ_s_, oko kukuthi, ukuhlalisa kwiyunithi nganye yomthamo womhlaba 1+e0 yi
Δ_s_ =(e0–e1) / (1+e0)
Ukuzinza kongqimba olusisiseko olunobukhulu dz kukuthi ngokwemz. 4b
Δ_s_ dz=(e0–e1) / (1+e0) dz
Ukuhlalela komaleko onobukhulu H kuya kuba
Ukuba sithatha ukuba p luxinzelelo kubunzulu z ngenxa yobunzima bomhlaba uqobo, oluhambelana nomthwalo σ0 kwi-edometer, Δp luxinzelelo olusuka kumthwalo owongezelelekileyo womhlaba ngenxa yesakhiwo, oluhambelana nokwanda komthwalo Δ_σ_ kwi-edometer, p1 luxinzelelo olupheleleyo phantsi kwempembelelo yobunzima bomhlaba uqobo kunye nomthwalo owongezelelekileyo oluhambelana nomthwalo opheleleyo σ1 kwi-edometer, ifomula engaphambili sinokuyibhala ngolu hlobo
Ukuba sibonisa ngo A indawo yediagram yoxinzelelo olusuka kumthwalo owongezelelekileyo womhlaba, A = Δ_pH_ (indawo enethunzi kumz. 4b), apho Δ_p_ luxinzelelo olusuka kumthwalo owongezelelekileyo embindini womaleko
a=Δ_e_/Δ_p_, umlinganiselo womahluko we-coefficient ye-porosity kwisingxobo esihambelanayo somthwalo owongezelelweyo V_c = (1+e0)/a, singabeka
oko kukuthi s = A/Vc [cm]
Ukuba umhlaba uqulunqwe ziimigangatho ezininzi, kubalwa iinokukha s zomaleko ngamnye; isixa seenokukha zomaleko ngamnye sibonisa inokwela iyonke Σ_s_.