N’okpuru mmetụta ibu, ala ọ bụla, ewezuga nkume siri ike, na-adakpu. Ndakpu n’ozuzu na-eme n’ihi ihe abụọ: ịkwakọba ala ya bụ ibelata olu ya n’ihi ịpụpụ ikuku ma ọ bụ mmiri n’ime oghere ya, na ịpụta ala n’akụkụ n’akụkụ ọnụ ntọala n’ihi ịsịgharị nke irighiri ala siri ike.
Sleganje ala n’ihi njikọ/ịkpakọ mejupụtara deformeshọn elastic na plastic, nke ibu ntọala kpatara, nke n’ime ha mgbe a kwụsịrị ibu, ala na-alaghachi akụkụ ụfọdụ n’ọnọdụ mbụ ya.
Sledanje n’ihi ịkwanye ala n’akụkụ mejupụtara naanị nrụrụ plastic, nke n’oge ibelata ibu ala anaghị alaghachi n’ọnọdụ mbụ ya. Ha na-apụta ọtụtụ mgbe n’ụlọ ntọala nta e wuru n’omimi nta n’okpuru elu ala. N’otu aka ahụ, ịkwanye ala n’akụkụ na-eme n’ala nke mmiri ya dị ukwuu ma akụkụ nke ntụgharị esemokwu n’ime ya dị ntakịrị.
N’ịtụle na a na-ewere ibu a na-ekwe ka ala buru n’ime mpaghara nke mmegharị elastik-plastik, a na-eme ngụkọta mgbada naanị dabere na mbelata nke oghere nke ala n’okpuru ibu, ebe a na-eleghara mgbada ndị sitere na ịkwali ala n’akụkụ, nke a na-ewere na ha abụghị ihe dị mkpa, anya.
Ịda ala n’ihi ịkọchi na-adabere na permeability nke ala, n’ihi na ọ na-eme n’ihi oghere, nke dị n’ime ala nke sitere n’okike na-adịkarị karịa ma ọ bụ obere jupụtara na mmiri. Ya mere, ịda ala nke ala n’okpuru ibu bụ n’ezie ihe omume hydrodynamic, n’ihi na usoro ịda ala na-adabere na ọsọ nke ịpụ mmiri n’ọnụ oghere, nke permeability nke ala nwere nnukwu ọrụ.
Ala na-ejikọtaghị ọnụ dịka nkume nta na ájá nwere nnukwu oghere, nke na-eme ka ikike ha ịgbafe mmiri bụrụ nnukwu, ya mere a na-apụpụ mmiri dị n’ime oghere ngwa ngwa n’okpuru ibu nke ntọala. N’ihi ya, na ala na-ejikọtaghị ọnụ, mgbada n’okpuru ibu nke ntọala na-eme ngwa ngwa, ọtụtụ mgbe ka na-eme n’oge a na-ewu ụlọ ma ọ bụ obere oge ka e mesịrị. N’ihi nke a, a na-anaghị agbakọkarị mgbada ntọala n’ala na-ejikọtaghị ọnụ.
Ala jikọrọ ọnụ nwere obere oghere, mmịfe mmiri ha dị ntakịrị, ma iwepụ mmiri n’ime oghere n’okpuru mmetụta ibu ntọala nwere ike ịdịte aka ogologo oge, n’ụfọdụ ụrọ dị nkenke ọbụna ruo ọtụtụ iri afọ. Tụkwasị na nke ahụ, ebe mkpokọta porosity nke ala jikọrọ ọnụ karịrị nke ala na-ejikọtaghị ọnụ nke ukwuu, ndakpu ala jikọrọ ọnụ dịkwa ukwuu karịa.
N’ihe gbasara ala jikọtara ọnụ, nke oghere ya jupụtara akụkụ ụfọdụ n’ime ikuku ma akụkụ ụfọdụ n’ime mmiri, mbu mbu na-apụta n’ihi mkpakọ nke ikuku dị n’ime oghere, mgbe ọdịnaya mmiri na-anọgide otu, mgbe e mesịrị mbu mbu n’ihi ikpochapụ mmiri n’ime oghere. N’ibu ala na-adịgide adịgide n’ihi mmetụta nke ịdị arọ na ibu ọrụ nke ntọala, ụdị abụọ a nke mbu mbu na-apụta, ma usoro oge nke mbu mbu dị iche.
E nwekwara ihe ndị ọzọ na-akpata ndakpu ala, dịka mbelata ọkwa mmiri dị n’okpuru ala na-adịgide adịgide, mgbanwe kemịkal n’ime ngwakọta ala na mmebi ndị ọzọ n’ime ala.
Nnyocha ndudue ala mejupụtara ngụkọta ndudue mbụ, nke a na-eme dabere na ule ụlọ nyocha nke ihe atụ ala na nlele ndudue, nke a na-eme n’oge a na-ewu ụlọ na ruo oge ụfọdụ mgbe nke ahụ gasịrị.
Ngụkọta nke ndudue ala n’ibu etiti nke ntọala
Ka anyị tụlee ntọala ụkwụ etinyere n’ala nke mejupụtara ọtụtụ akwa dị iche iche, dịka ọmụmaatụ akwa ájá H0, ya bụ H1 n’okpuru ụkwụ ahụ, akwa ala ụrọ nke ịdị arọ H2, akwa ụrọ mkpụrụ nta nke ịdị arọ H3, n’okpuru ya bụ gravel a kpokọtara nke nwere ịdị arọ oyi akwa ka ukwuu, yana ọkwa mmiri dị n’okpuru ala NPV (onyo 1a).
Iji gbakọọ sleganja, a chọrọ itinye eserese nrụgide n’ihi ịdị arọ nke ala n’onwe ya (eserese aka ekpe na sl. 1b) na eserese nrụgide n’ihi mmetụta ibu mgbakwunye sitere n’ụlọ ntọala (eserese aka nri na sl. 1b). A na-enweta eserese nrụgide n’ihi ịdị arọ nke ala n’onwe ya site n’ịdị arọ oyi akwa Σ_H_ na ịdị arọ olu ha γ. Ọ bụrụ na ịdị arọ olu nke ájá bụ γ1, ájá n’okpuru mmiri γ’1, ala ụrọ n’okpuru mmiri γ’2, ụrọ n’okpuru mmiri γ’3, nrụgide mkpakọ n’ala sitere n’ịdị arọ nke ala n’onwe ya ga-adị otú a (sl. 1)
γ1 · H’; γ’1 · H’’; γ’2 · H2; γ’3 · H3;
A na-enweta eserese nrụgide n’ihi mmetụta nke ibu site n’ịgbakọ ya site n’otu n’ime usoro a maara nke ọma, dịka ọmụmaatụ site na Steinbrenner ma ọ bụ Newmark, maka omimi dị iche iche n’okpuru ntọala.
Ọ bụrụ na anyị gosi ibu ntọala site na P, mpaghara ya nke na-adụ na ala site na A, arọ olu nke ala n’ịdị omimi ntọala t n’okpuru elu ala site na γ1, ibu kpọmkwem nke ntọala bụ P/A ebe arọ nke ala n’otu omimi ahụ bụ γ1t. Ka e wee nweta ibu mgbakwunye nke ala n’ihi ibu ntọala, a ghaghị iwepu nrụgide arọ nke ala γ1t n’ibu ntọala P/A, ya mere ibu mgbakwunye nke ala bụ
p0 = P/A – γ1t.
N’otu omimi t ahụ, nrụgide γ1t n’ihi ibu nke ala n’onwe ya na-arụkwa ọrụ, ya mere n’ọkwa omimi a nrụgide ngụkọta (P/A – γ1t) + γ1t, na-arụ ọrụ, ebe nchikota ala n’okpuru nrụgide γ1t emeelarị tupu iwulite ihe owuwu ahụ.
Sl. 1. Ngbakọ nke mmebi ala n’okpuru ibu etiti nke ntọala
Otú ọ dị, ọ bụrụ na a na-ekpuchi otu akụkụ nke ntọala dị n’elu footing ntọala na ala (fig. 1c), a ga-atụle ibu nke ala e juru 2_Q_, nke mere na n’ọnọdụ ahụ ibu mgbakwunye bụ
_P+2_Q/A – γ1t.
Maka ntọala ụdị eriri bụ A = b x 1,0 m na 1 m’ nke ntọala.
A na-eme mgbakọ maka nhịpụta ala maka oyi akwa niile nke ala nwere ike ịdaba ruo omimi nke mmetụta ibu ntọala. Tupu oge a, a na-ewere dịka ókè nke mmetụta ibu ihe owuwu omimi ruo ebe nrụgide nke ịdị ike ≥ 10% p0 na-adị. Taa, a na-anabata na ókè a dị na omimi ebe nrụgide sitere na ibu mgbakwunye pz hà 20% nke nrụgide sitere na ịdị arọ nke ala: pz = 0,2 ·γ_Σ_H. N’okpuru omimi a, a naghị agbakọ nhịpụta ala. Dị ka iwu ọzọ, a na-atụ aro mgbakọ nhịpụta ala maka oyi akwa ruo omimi 2_b_ ruo 3_b_, ebe b bụ obosara ntọala. Ọ bụrụ na n’ikpeazụ e nwere oyi akwa gravel dịka na sl. 1a, a naghị etinye ya n’uche maka mgbakọ nhịpụta ala, n’ihi na nhịpụta ya n’okpuru ibu ntọala adịghị ukwuu ma na-eme n’oge owuwu.
N’ime omimi z n’okpuru ụkwụ ntọala, e nwere nrụgide ịkpụ pg n’ihi ịdị arọ nke ala n’onwe ya (sl. 1b), ebe e bukwara n’uche mmetụta nke uzorọ. A na-agbakwunye na nrụgide mbụ a nrụgide pz n’ihi mmetụta ibu ụlọ n’otu omimi ahụ. Ya mere, n’otu ebe ọ bụla M n’ime omimi z n’okpuru ụkwụ ntọala, nrụgide ịkpụ zuru ezu pn = pg + pz na-adị.
N’okpuru ibu mgbakwunye, ala na-adaba ma na-agbagọ n’akụkụ. Ọ bụrụ na a hapụ mgbanwe akụkụ ndị a anya, n’ihi na ha dị ntakịrị n’ihe atụnyere, ebe ibu ala a na-ekwe na mpaghara mgbanwe elastik-plastik, enwere ike ịnakwere na a na-eme ngụkọta mgbada dabere na ule mkpakọ n’ime edometa, jiri ihe atụ na-adịghị agbagwoju anya ewepụtara n’ógbè ebe a na-enyocha n’ala, nke a na-eji kpebie modul mkpakọ ala Ms.
Dabere na iwu Hooke, anyị nwere
Δ_s_ = pz/Ms,
ebe Δ_s_ bụ settlement pụrụ iche, kwa otu ọkpụrụkpụ nke oyi akwa, pz bụ nrụgide n’omimi ala z n’ihi ibu mgbakwunye.
Ọ bụrụ na anyị were na ọkpụrụkpụ nke oyi akwa dz dị obere nke ọma, ka e nwee ike ịnakwere pz na Ms dị ka ndị na-adịgide adịgide, selyement isi ga-abụ
Δ_s dz_ = pz/Ms dz.
Ncheda zuru ezu nke oyi akwa nwere ọkpụrụkpụ H ga-abụ
Ọ bụrụ na pZ na MS dịgide otu maka akwa nke ịdị arọ H, ọ ga-abụ
s = pz/Ms · H.
N’eziokwu, pz na Ms abụghị ndị na-adịgide otu ihe n’ime oyi akwa nke ịdị arọ ya bụ H1, kama a na-ewere ụkpụrụ etiti ha n’ebe M dị.
A na-ekpebi modul compressibility nke ala Ms site na nyocha ụlọ nyocha maka oyi akwa ọ bụla iche iche. Maka ala a konsolidatara n’ụzọ nkịtị, a na-ekpebi modul Ms site na eserese nke primary compression, ebe ibu zuru ezu bụ σ2 = pg + pz; σ1 = pg = Σ_γt,_ ibu mgbakwunye Δ_σ_ = σ2 – σ1 = (pg + pz) – pg, ma ụkpụrụ kwekọrọ nke compression mmekọrita bụ Δ_h2_/h na Δ_h1_/h, ya mere ọ bụ
Otú ọ dị, ọ bụrụ na ọ bụ ụrọ a kpakọbara mbụ ugboro, mgbe ahụ a na-ekpebi modulus nke nrụrụ site na eserese nke mkpịsị nrụgide nke abụọ. Site n’ihe atụ dị na sl. 2 anyị nwere maka:
Sl. 2. Nkpebi modul nke compressibility nke ala dabere na diagram nke compression n’akụkụ aka
Site n’ihe e kwuru n’elu, ọ na-apụta na sleganje nke ụrọ a kara aka tupu oge ya ga-adị obere nke ukwuu karịa sleganje nke ala a kọnsọdere nke ọma n’ụzọ nkịtị.
Mmetụta ike nke ntọala na ntughari ala
Ọ bụ ezie na n’eziokwu enweghị ntọala na-agbanwe agbanwe zuru oke, nke mmebi nke otu ebe ga-adabereghị na mmebi nke ebe dị n’akụkụ, maka mgbako ndakpu a na-ekewa ntọala na-agbanwe agbanwe na ntọala siri ike.
Ntọala elastik, nke a na-aghọta dị ka nkwakọba nkume na mkpọda, n’ibu nke na-agbakọ n’otu aka hà, na-eme ka n’ebe ụfọdụ sie ike sụda nke dị iche iche. N’ihi nke a, n’ụdị ntọala ndị a, a naghị eme mgbakọ sụda maka elu dum e tinyere ibu, kama maka ebe ụfọdụ n’ime ya: akụkụ nkuku A, B, C na D, ebe etiti akụkụ E, F, H na J na ebe etiti G nke elu akụkụ anọ ahụ (sl. 3). N’ibu hà hà, sụda nke ebe B, C na D bụ otu dịka nke ebe A, sụda nke ebe H bụ otu dịka nke E, ebe J dịka nke F maka ala nke otu ụdị mejupụtara.
Sl. 3. Ngbakọ ndaba nke isi ihe ụfọdụ nke elu ebu ibu
Iji gbakọọ ọdịda ala n’okpuru otu isi G ọ bụla nke elu e tinyere ibu, a na-ekewa akụkụ anọ ABCD n’ime akụkụ anọ dị nta, a na-enwetakwa ọdịda G dịka nchikota nke ọdịda nke akụkụ nke ọ bụla e kewara na-akpata.
Ntọala siri ike adịghị dobe n’otu ụzọ dị ka ndị na-agbanwe agbanwe, n’ihi na n’ime ha a pụghị inwe ida n’otu ebe n’otu ebe. Ya mere, a na-agbakọ ida nke ntọala siri ike dịka otu ihe, ebe a na-ekpebi nkezi uru nke ida n’ụzọ dị iche dabere na ogo isi ike, n’ihi na nkesa nrụgide n’ala ntọala na-adabere na isi ike ntọala.
Maka ntọala siri ike nke nwere ụdị square ma ọ bụ akụkụ anọ nta, ebe a < 2_b_, a na-agbakọ ida sG nke etiti G ma nabata ida zuru ezu nke ntọala s = 3/4 sG. Maka ntọala siri ike nke nwere ụdị akụkụ anọ gbatịrị agbatị ma ọ bụ ụdị eriri, a na-agbakọ ida nke njedebe E, nke etiti G na nke ebe M nke dị n’etiti ha, n’akụkụ ogologo axis nke nkwado ntọala, ma a na-ewere uru etiti.
Van Hamme na-ewere na mgbakọ ziri ezi karị nke ndaba nke „ihe pụrụ iche P“, nke dị n’ebe dị anya site na axis etiti
site n’osisi etiti. Dị ka Van Hamme si kwuo, ida nke ụfọdụ ebe kpọmkwem nke ntọala adịghị adabere n’ụzọ a na-ekesa nrụgide n’ala ntọala. Maka ebe ndị a, a pụrụ ịgbakọ ida ahụ n’okwukwe na nkesa nrụgide n’ala ntọala bụ nke hà nha. Maka footings siri ike, e tinyere ibu hà nha, ebe nkesa nrụgide n’ala ntọala na-adịghị hà nha ma na-abawanye n’akụkụ ọnụ nke footing, n’agbanyeghị nke a ida nke footing ahụ hà nhata na ida nke isi ebe P. A pụrụ ịgbakọ nrụgide n’omimi z n’okpuru isi ebe P nke elu akụkụ anọ nwere ogologo a, obosara b, e tinyere ibu hà nha p0 site n’enyemaka nke tebụl 1 nke Jelinek mere.
Nrụgide σzP n’ime omimi z n’okpuru isi ebe P bụ σzP = (σz/p0)·p0, ebe p0 bụ ibu mgbakwunye nke ala.
Table 1. Uru σz/p maka nrụgide n’okpuru isi ihe P dabere na mmekọrịta omimi z na obosara b yana na mmekọrịta ogologo a na obosara b nke ntọala ụkwụ
Ngụkọta mgbada dabere na mgbanwe nke ọnụọgụ oghere nke ala
Ọ bụrụ na anyị kpọọ e0 ọnụọgụ oghere nke ihe atụ na-adịghị emebi emebi nke e wepụtara n’akụkụ ala, na ei ọnụọgụ oghere nke otu ihe atụ ahụ mgbe e mechara konsolideshọn n’ime edometer n’okpuru ibu σ1 (sl. 4a), mbelata nke olu mbụ nke ala n’okpuru mmetụta nke ibu Δ_σ_ kwekọrọ na mbelata nke oghere ya, ya bụ ọnụọgụ oghere nke ala
Δ_e_ = e0 – e1
Sl. 4. Ngụkọta mgbada ala dabere na mgbanwe nke ọnụọgụ oghere nke ala
Olu mbụ nke ihe nlele ala bụ
Mbelata pụrụ iche Δ_s_, ya bụ, mbelata kwa otu olu nke ala 1+e0 bụ
Δ_s_ =(e0–e1) / (1+e0)
Sleganje nke oyi akwa elementrị nke nwere ọkpụrụkpụ dz bụ dịka fig. 4b
Δ_s_ dz=(e0–e1) / (1+e0) dz
Ịdaba ala nke oyi akwa nwere ọkpụrụkpụ H ga-abụ
Ọ bụrụ na anyị ewere na p bụ nrụgide n’ime omimi z sitere n’arọ nke ala n’onwe ya, nke kwekọrọ na ibu σ0 n’ime edometer, Δp bụ nrụgide sitere na ibu mgbakwunye nke ala n’ihi ụlọ, nke kwekọrọ na mmụba ibu Δ_σ_ n’ime edometer, p1 bụ nrụgide mkpokọta n’okpuru mmetụta arọ nke ala n’onwe ya na ibu mgbakwunye nke kwekọrọ na ibu mkpokọta σ1 n’ime edometer, anyị nwere ike ide usoro mbụ n’ụdị
Ọ bụrụ na anyị kpọọ A mpaghara nke diagram nrụgide sitere n’ịbawanye ibu ala ọzọ, A = Δ_pH_ (mpaghara e kpuchiri akara na sl. 4b), ebe Δ_p_ bụ nrụgide sitere n’ịbawanye ibu ọzọ n’etiti oyi akwa
a=Δ_e_/Δ_p_, mmekọrịta dị n’etiti ọdịiche nke ọnụọgụ porosity na nrụgide kwekọrọ na ya site na ibu mgbakwunye Vc = (1+e0)/a, anyị nwere ike dee
ya bụ s = A/Vc [cm]
Ọ bụrụ na ala nwere ọtụtụ oyi akwa, a na-agbakọ mfu mmefu s maka oyi akwa ọ bụla; ngụkọta nke mfu nke oyi akwa ndị ọ bụla na-enye mkpokọta mfu Σ_s_.