Ka ʻikamu o ka lepo
Ma lalo o ka hana o ka lepo ua manaʻo ʻia ke ʻano o ka hoʻonohonoho ʻana o ke kahua paʻa i loko o ka nui lepo. E like me ka ʻike, ua haku ʻia ka lepo i nā ʻāpana paʻa a me nā pore i piha i ka wai, ka ea a i ʻole ka mahu wai, ma ka hapanui he hapa ea a he hapa wai. Wahi a ka hoʻonohonoho ʻana o nā ʻāpana paʻa i loko o ka lepo, ua hoʻoholo ʻia kona ʻano. ʻOkoʻa loa nā ʻano o ka lepo ʻāweo ʻole a me ka lepo paʻa i waena o lāua.
ʻO ka hana o ka lepo ʻāweo ʻole
Lilo ka ʻōnaehana o ka lepo haʻahaʻa ʻole ma lalo o ka hana a ka umekaumaha. ʻO nā ʻāpana paʻa o kēia lepo he nui aʻe ka nui a hāʻule i lalo, waiho ma lalo o ka hana a ka umekaumaha, ʻoiai ʻaʻole loaʻa a liʻiliʻi loa paha nā ikaika huki intermolecular o ia mau ʻāpana a ua lanakila ʻia e ka umekaumaha. No laila, i ka lepo haʻahaʻa ʻole, kau nā ʻāpana paʻa kekahi ma hope o kekahi, e lawe ana i ka wahi manuahi ma waena o nā ʻāpana i kau ʻia (kiʻi 1_a_). Inā kokoke poepoe ke ʻano o nā ʻāpana o ka lepo haʻahaʻa ʻole a like ka nui, e like me ke ʻano o ke one me ke ʻano like, a laila hiki i ka ʻōnaehana ke lilo i ʻoi loa ka paʻa (kiʻi 1_b_) a i ʻole ʻoi loa ka laha (kiʻi 1_c_), ma muli o ka hoʻonohonoho ʻana o nā ʻāpana paʻa i loko o ka lepo. Kūlike ka ʻōnaehana ʻoi loa ka paʻa me ka hiki nui loa o ka paʻa ʻana o ka lepo haʻahaʻa ʻole a ʻo kona porosity ʻo nmin=26%. Kūlike ka ʻōnaehana ʻoi loa ka laha me ka hiki liʻiliʻi loa o ka paʻa ʻana o ka lepo haʻahaʻa ʻole a ʻo kona porosity ʻo nmax=48%. No laila, e laʻa me ke one palahalaha o nā one puʻu he n=47%.
Fig. 1 ʻO ke kūkulu o ka lepo hoʻopaʻa ʻole ʻia
Inā he lepo pili ʻole me nā nui ʻokoʻa o nā palaoa, pēlā e hoʻopiha ai nā ʻāpana liʻiliʻi i nā hakahaka ma waena o nā mea nui aʻe (kiʻi 2), ʻoi aku ka liʻiliʻi o ka porosity o ka lepo (n=20% a emi iho).
Kiʻi. 2. Ka ʻōnaehana o ka lepo haʻahaʻa ʻole o nā nui like ʻole o nā kīʻaha
Ke kūkulu o ka lepo paʻa
Ma ka lepo pili, ʻokoʻa ka ʻuhane o ka hale ma mua o ka lepo hui ʻole. Ma ka lepo pili, kū mai nā ikaika cohesion, ʻoi aku ka ikaika ma mua o ka ikaika huki o nā ʻāpana liʻiliʻi a hoʻopili iā lākou ma nā ʻili pākuʻi. No laila, ʻaʻole hāʻule kēia mau ʻāpana i lalo ma ke kaʻina, akā noho pū lākou i kāpili ʻia kekahi ma luna o kekahi a kekahi ma ka ʻaoʻao o kekahi (kiʻi 3_a_), a pēlā e hana ai i kahi ʻuhane kaulahao-lāʻau (kiʻi 3_b_), ʻālohilohi (kiʻi 3_c_) a pēlā aku, i kapa ʻia he ʻuhane o ke kiʻekiʻe ʻoi aʻe. Nui ka porosity o nā ʻuhane pēlā, hiki ke piʻi i 60-80% o ka nui holoʻokoʻa, ʻaʻole hiki pēlā i ka lepo hui ʻole.
Kiʻi 3. Ka ʻilikai o ka lepo paʻa
Porosity a me ka koefisiana porosity
Hoʻohālikelike ʻia ka porosity o ka lepo ma ke ʻano o ka ratio o ka nui o nā puka i ka nui holoʻokoʻa o ka lepo (kiʻi 4).
Sl. 4. Ka porosity a me ke koefisienta porosity o ka lepo
Inā mākou e hōʻailona me
- Vp = ka nui o nā puka i loko o ka lepo
- Vm = ka nui o nā ʻāpana paʻa
- V = ka huina leo o ka lepo,
ma ka wehewehe ʻana, ʻo ka porosity o ka lepo n
n = VP / V = VP / (VP + Vm),
ʻo ia hoʻi ma ka % o ka nui piha o ka lepo
n = 100 * VP / (VP + Vm) %.
Hoʻohālikelike ʻia ka koefisita porosity o ka lepo e ka lākiō o ka nui o nā lua i ka nui o nā ʻāpana paʻa:
e = VP / Vm.
Mai ke kumu no ka porosity n loaʻa iā mākou:
nVP + nVm = VP, no laila ʻo Vm = VP(1-n) / n.
Ma ka pani ʻana i kēia waiwai i loko o ke ʻano no e loaʻa iā mākou
e = n / (1-n).
Mai kēia hoohālike loaʻa iā kākou
e - ne = n; n = e / (1 + e).
Hōʻike ka koefisina o ka porosity i ka mānoanoa o ka lepo. Inā ʻoi aku ke koefisina e, emi iho ka mānoanoa o ka lepo, a ʻo ka mea ʻē aʻe nō hoʻi. Inā hoʻopaʻa ʻia kekahi lepo hiki ke kōmi ma lalo o ka ukana, hiki ke hoʻoholo ʻia ka nui o ka hoʻopaʻa ʻana Δ_h_ ma o ka koefisina porosity ma mua a ma hope o ka hoʻopaʻa ʻana.
E nānā kākou i ka papa lepo hiki ke hoʻemi ʻia o ka mānoanoa h (sl. 5_a_). Inā hoʻouka ʻia kēia papa, e noho iho ia i ke kiʻekiʻe Δ_h_, no laila e emi ai kona mānoanoa ma muli o ka ukana i h1. No laila
Δ_h_ = h – h1.
No ka mea, hana ʻia ka emi ʻana o ka lepo hiki ke kāpili ʻia ma muli o nā lua, no ka mea ʻaʻole hiki ke kāpili ʻia nā ʻāpana paʻa, a pēlā pū hoʻi ka wai, inā ua piha hapa a piha loa nā lua o ka lepo iā ia, hiki ke hōʻike ʻia kēia emi ʻana ma ke ʻano kiʻi ma ke kiʻi 5_b_.
Kiʻi 5. Ka noho ʻana Δh o ka papa lepo hiki ke kōmi ʻia me ka mānoanoa h ma lalo o ka ukana
Inā mākou e hōʻailona me h0 i ke kiʻekiʻe i noʻonoʻo ʻia o ka papa o nā ʻāpana paʻa me ka ʻole o nā pūnāwai, i kapa ʻia ka kiʻekiʻe i hoʻemi ʻia, a laila hiki iā mākou ke hōʻike i ka hāʻule ʻana Δ_h_ e pili ana i ka kiʻekiʻe i hoʻemi ʻia h0 ma kēia pilina:
Inā nānā ʻia kahi papa lepo me ka laulā a me ka lōʻihi like me ka ʻāpana hoʻokahi, a laila ʻo nā kiʻekiʻe h, h1 a me h0 he mau nui ia, no laila he
ma kahi o e ke koefisiana o ka porosity ma mua, e1 ma hope o ka noho ʻana. Mai ka mea i ʻōlelo ʻia ma mua, loaʻa ka noho ʻana
Δ_h_ = h0 (e-e1).
Hiki ke hōʻike ʻia ka noho ʻana e pili ana i ke kiʻekiʻe o ka papa h ma mua o ka noho ʻana inā hoʻololi mākou i ka waiwai o ke kiʻekiʻe i hōʻemi ʻia h0:
h0 = h – nh = h (1-n) = h / (1+e),
no ka mea n = VP / V = VP / h_,_ mai laila ua VP = nh.
No laila, loaʻa
Loaʻa i nā ʻano lepo ʻokoʻa nā waiwai awelika penei o ka porosity n a me ke koefesina porosity e:
Māmā o ka lepo
Nā ʻano wai i loko o ka lepo
Hōʻike ʻia ka wai ma ka lepo ma ke ʻano he wai i loko o nā pores ma waena o nā ʻāpana paʻa, ʻo ia ka mea i kapa ʻia he wai pores, a laila ma ke ʻano he wai adsorbed ma nā ʻāpana paʻa a ma ke ʻano he wai konstitutive.
ʻO ka wai o nā pori he hui ʻia mai ka wai kūʻokoʻa ma waena o nā ʻāpana paʻa, nona ka neʻe ʻana e holo ana e like me ke kānāwai a Darcy, a laila ka wai umekaumaha, e neʻe ana ma lalo o ka hana a ka umekaumaha mai luna iho i lalo i nā kuhikuhi a pau, akā ʻaʻole hana kona neʻe ʻana e like me ke kānāwai a Darcy, ka wai kapilari e neʻe ana ma lalo o ka hana a nā ikaika kapilari a me ka wai o ke kaomi ili, i paʻa ʻia e ke kaomi ʻili i nā kihi ma waena o nā ʻāpana paʻa o ka lepo a kapa ʻia hoʻi he wai pori kihi. Hiki ke hoʻoneʻe loa ʻia kēia wai a pau ma ka hoʻomaloʻo ʻana i ka lepo ma ka mahana o 110oC.
ʻO ka wai adsorbed ka mea e uhi ana i nā ʻāpana paʻa, i pili ʻia me lākou ma nā ikaika molekala. ʻO kēia ka mea i kapa ʻia he kiʻi wai, nona ka mānoanoa e kū ana i ka 6-80 µµ (1µµ=10-6 mm, milimikrona). ʻAʻole nui ka hopena o ka wai adsorbed ma nā ʻāpana nui, akā inā ʻoi aku ka liʻiliʻi o nā ʻāpana, ʻoi aku ka nui o kona hopena, no ka mea e piʻi ana ka ʻāpana ʻili nui o nā ʻāpana a pēlā pū ka lākiō o ka wai adsorbed i nā ʻāpana paʻa i loko o ka pūʻolo o ka lepo. Hiki ke wehe hapa wale ʻia kēia wai ma ka hoʻomaloʻo ʻana ma 110oC.
ʻO ka wai konstitutive he mea hoʻohui kemika i loko o nā kristala o nā minela o nā ʻāpana paʻa o ka lepo. He liʻiliʻi loa kēia wai a ʻaʻole hiki ke wehe ʻia ma ka hoʻomaloʻo ʻana i ka lepo. No laila, hiki ke noʻonoʻo ʻia kēia wai he ʻāpana kumu o ka ʻāpana paʻa.
Ka nui o ka wai i ka lepo
Ma ka wehewehe ʻana, ʻo ka nui o ka wai i loko o ka lepo a i ʻole ka pulu o ka lepo ka lākiō ma waena o ke kaumaha o ka wai i loko o ka lepo a me ke kaumaha o kona mau mea paʻa. Ma muli o ka nui o ka wai i loko o ka lepo, ʻekolu nā hihia: ka lepo i piha loa i ka wai, ka lepo i piha hapa i ka wai, a me ka lepo maloʻo loa.
Ka lepo i piha loa i ka wai
Inā hōʻailona ʻia me n ka porosity o ka lepo, γs ke kaumaha volume o nā ʻāpana a pau, a γw ke kaumaha volume o ka wai, a laila hiki ke hōʻike ʻia ka makū o ka lepo piha wai wZ me kēia hoohalike
Lepo i māʻona hapa i ka wai
Inā hōʻailona mākou i ka kaumaha o ka wai i loko o ka lepo me Ww, a me ke kaumaha o nā ʻāpana paʻa, ʻo ia hoʻi ka kaumaha maloʻo o ka lepo, me Wd, a laila ʻo ka māʻona wai o ka lepo he w
w = Ww / Wd , ʻo ia hoʻi, ma nā pākēneka o ke kaumaha maloʻo o ka lepo: w = 100 Ww / Wd.
Ma kēia hihia hiki ke hōʻike ʻia ka pulu o ka lepo ma o ke kēkelē o ka pulu Sr e hōʻike ana i ka lākiō ma waena o ke kaumaha maoli o ka wai i loko o ka lepo a me kēlā kaumaha o ka wai i loko o ia lepo hoʻokahi, inā i piha nā puka liʻiliʻi a pau i ka wai, ʻo ia hoʻi ma ka kaumaha o ka wai o ka lepo i piha i ka wai:
ʻo ia hoʻi no _γ_w = 1,00 Sr = w*γs / e.
ʻO nā waiwai palena no ke kiʻekiʻe o ka pulu, penei:
- no ka lepo maloʻo loa w = 0; Sr = 0
- no ka lepo piha loa i ka wai w = e/γs; Sr = e/γs * γs / e = 1,0.
Kii. 6. Laʻana lepo i hoʻopiha hapa ʻia me ka wai
ʻO ke pae o ka māʻona (i kapa ʻia i kekahi manawa he māʻona a i ʻole ke kūlana mākū) ua hōʻike pū ʻia ma ka lākiō o ka nui o nā lua i piha i ka wai i ka nui holoʻokoʻa o nā lua (kiʻi 6):
Sr = V2 / V1
kahi ʻo V2 ka nui o nā pūwā i piha i ka wai, V1 ka nui holoʻokoʻa o nā pūwā i piha i ka wai, ka ea a me nā kinoea. Inā ʻo w ka pulu o ka lepo ma ka % o ke kaumaha maloʻo o ka lepo Wd, laila loaʻa iā kākou
V2 * γW = w Wd, no laila ʻo V2 = w Wd / γw.
Ma kekahi ʻaoʻao, loaʻa iā mākou ʻo V1 = V – Vd, a no ka mea ʻo Vd * γs = Wd, no laila
Vd = Wd / γs a me V1 = V – Wd / γs.
No laila, e lilo ka pae māʻona o ka lepo Sr i
ʻo ia hoʻi ma nā pākēneka o ka kaumaha maloʻo o ka lepo
Lepo maloʻo loa
I kēia hihia, w = 0. Ua hoʻoneʻe ʻia ka wai pore a pau, ʻoiai ua hoʻoneʻe wale ʻia ka wai i hoʻopili ʻia ma kahi ʻāpana, ʻo ia hoʻi, aia nō ke kiʻi wai, akā ua emi kona mānoanoa.