Te kaha kawe o te oneone

I roto i te mīhini o te oneone ka whakatauria te kaha kawe here o te oneone me te kawenga e whakaaetia ana o te oneone.

Ko te mahi kawe mutunga o te oneone, ko taua mea e tutuki ana i te wā ka puta te pakarutanga o te oneone. Ka puta te pakarutanga o te oneone i te wā ka nui ake te kawenga e pā ai te tūāpapa ki te oneone i tōna kaha kutikuti. I taua take, i raro i te pānga o te kawenga o te tūāpapa P ka puta ngā mata aukati iti rawa ACD me BCE – ngā mata retireti wh. 1, e panaia ai te oneone ki te taha, ā, i te wā kotahi ka ara ake te oneone i runga ake i te mata o te whenua i te taha o te hanganga DG me EF, i te wā e totohu ana te tūāpapa ake.

Wh. 1. Te pakarutanga o te oneone i raro i te pānga o te kawenga tūāpapa

Ka piki ake te kaha kutikuti o te oneone i te hōhonutanga o te tūāpapa t, nā te mea ka heke te āheinga ki te kōpeke taha nā te taumaha o ngā paparanga o runga. Nō reira, he uaua ake i ngā tūāpapa hōhonu te whakaoho i te whati o te oneone, ā, he mōrearea ake ngā tūāpapa pāpaku mō te whati. Waihoki, he uaua ake i ngā tūāpapa whānui te whakaoho i te whati o te oneone, nā te mea he hōhonu ake ngā mata reti.

The allowable load on the soil is that which may be permitted to act on the soil so that soil failure is not caused under the most unfavorable possible conditions. The allowable soil load is determined on the basis of the ultimate bearing capacity of the soil by applying a safety factor. The magnitude of the safety factor depends on several factors, among which the most important are the accuracy of the physical characteristics of the soil, the possibility of changes in the values of the elements of the soil’s internal resistance, especially cohesion, whose value may vary widely under the influence of water in the soil, and then the influence of possible other factors, such as loading conditions (the possibility of sudden and dynamic loading), foundation depth, and footing width.

Ka taea te whakatau i te kaha kawe o te oneone i runga i te pakarutanga o te oneone, nā reira ka puta te kaha kawe rohe. Ko te tikanga o te kaha kawe rohe o te oneone ko te nui o te kawenga e whakaputa ana i te pakarutanga. E rua ngā huarahi hei whakatau i te kaha kawe rohe i runga i te pakarutanga o te oneone, arā ko te otinga pāngarau me te kawenga whakamātau.

Rongoā pāngarau

He tokomaha ngā kaipūtaiao i ngana ki te kimi otinga pāngarau hei whakatau i te kaha kawe paepae o te oneone, i runga i te mōhiotanga ki ngā āhuatanga whakaaweawe me raro i ngā whakapae rerekē mō ngā tikanga whati. Ko ngā āhuatanga whakaaweawe ko ngā āhuatanga ā-tinana o te oneone, e whakatauria ana e ngā whakamātau taiwhanga i runga i ngā tauira oneone kāore i whakararuraru, te āhua o te wai ā-whenua, te hōhonutanga o te tūāpapa, te rahi me te āhua o te mata e utaina ana, me te momo utanga, arā, he ōrite, he koretake rānei, he utanga pokapū, he utanga hākerekere rānei o te oneone. Ko ngā whakapae mō ngā tikanga whati e tūāpapa ana ki te ariā kirihou me te ariā pūhū. Heoi anō, ko ngā tikanga hou mō te whakatau i te kaha kawe o te oneone e tūāpapa ana ki te ariā kirihou, ka whakakotahitia ki ētahi whakapae whakangāwari.

Anei ka whakaaturia ētahi tikanga tātai rongonui mō te whakatau i te kaha kawe rohe, arā te kawenga e whakaaetia ana o te oneone.

Tauira Prandtl-Caquota

Ki te whakatūria te papa tūāpapa AB ki te hōhonutanga t i raro iho i te mata o te whenua, i tēnei hōhonutanga ka noho te pēhanga whakapā p nā te kawenga o te tūāpapa, me te pēhanga taha p=γt nā te taumaha o te oneone kei runga ake i te taumata o te papa tūāpapa tae noa ki te mata o te whenua (wh. 2).

I raro i te awe tōtika o te taumaha o te tūāpapa, i te wā e hipa ana te kaweuta mutunga o te oneone, ka puta ngā papa retireti tika AC me BC, e hanga ana i te koki α = 45° + ϕ/2 ki te mata utaina. Ko ēnei papa retireti ka waihanga i te poro oneone kaha ABC.

Wh. 2. Ngā mata retireti āhua tōrino rōrā i raro i te kawenga pūwāhi o te papa tūāpapa e ai ki a Prandtl-Caquot

I raro i te pēhanga o te piriti oneone kaha ka hangaia ngā piriti oneone ngoikore taha ADD1 me BEE1, e whai ana ia kia pana whakarunga i ngā mata reti DD1 me EE1, i raro i te koki 45°-ϕ/2 ki te pae-horapa. I waenga i te rohe o te pēhanga oneone kaha me te pēhanga oneone ngoikore kei reira te rohe kutikuti ā-rārahi ACD arā BCE, e puta ai te reti i runga i ngā mata reti kōpiko ina hipa i te taurite tōpū. I tatauria e Résal, he āhua tōrino rārangi-rauemi ngā mata reti i te rohe kutikuti ā-rārahi, he pou kei A arā B, ā, ko tōna whārite r=r0 eπ tg_ϕ_

Hei whakatau i te kawenga pae o te oneone, i mahia ēnei whakapae e whai ake nei:

• kia maheni te tūāpapa, arā, ka whakaarohia he iti noa te waku i waenga i te papa tūāpapa me te oneone;
• kia kore ai te kaha kutikuti o te oneone i ngā mata D1M me E1N e noho, arā ka whakakāhoretia;
• e whakaarotia ana ko te taumaha pūtautau o te oneone kei raro i te papa o te tūāpapa γ=0, arā, kāore e arohia te pānga o te taumaha o te oneone i raro i te papa tūāpapa, kei roto i te rohe taurite kirihou.

Ko te tauira Prandtl-Caquota e pērā ana:

Ko te kaha kawe rohe o te oneone ko

Mēnā ka whakatakotoria e tātou:

ko te kaha kawe rohe o te one here ko qf = γtm + cm1.

Mō ngā uara rerekē o te koki waku ā-roto o te oneone, kei te ripanga 1 ngā uara mō m me m1.

Ripanga 1. Ngā uara o ngā taupū m me m__1 mō ngā uara rerekē o te koki waku ā-roto o te oneone

Ko te kawenga oneone e whakaaetia ana ko qa = pdozv = qf/F kei reira ko F te taupū haumaru. Mō te whakamahi i te tauira Prandtl-Caquot, ka tangohia F = 4, nō reira ko qa = qf/4.

Te tātai a Terzaghi

I hoatu e Terzaghi tētahi tauira ā-pāngarau hei tātai i te kaha kawe mōrahi o te oneone i raro i te pānga o ngā kawenga ā-ahua pēnei i te rīpene, te tapawhā me te papa porowhita. I tirohia e ia tētahi tūāpapa i whakatūria ki te hōhonutanga Df i raro i te mata o te whenua, te whānui B (fig. 3), ā, i whakaaetia he waku kei waenganui i te takapū tūāpapa AB me te oneone, e ārai ana i te pana taha o te oneone, ā, ko ngā papa retireti AB me BC e hanga ana i te koki o te waku ā-roto ki te mata e utaina ana.

Wh. 3. Te kaha kawe rohe o te oneone e ai ki a Terzaghi

Nā reira, ka noho te oneone i roto i te āhua kōpaki oneone ABC, e mau ana i waenga i te tūāpapa AB me ngā mata reti AC me BC, i te āhua taurite māro, ā, ka whanonga pēnei i tētahi wāhanga o te tūāpapa. Kāore e taea te pana i te parata ABC kia tae rā anō ngā pēhanga ki ōna taha AC me BC kia ōrite ki te pēhanga oneone tūāuriuri o ngā parata taha, arā, i te wā ka hipa te āhuatanga mutunga o te taurite, ka mahi te pēhanga hua o te oneone q i raro i te koki ϕ ki te poutū ki te mata reti, arā, i te ahunga poutū (wh. 3). I te mea ka neke poutū whakararo te kōpaki i raro i te pānga o te kawenga, ka whakaitia te raruraru o te taurite i te oneone ki te whakatau i te pēhanga oneone tūāuriuri. Heoi, nā te mea he uaua te tātai tika o te kaha kawe o te oneone mā tēnei tikanga, nā Terzaghi i hoatu tētahi otinga māmā. Ko te tauira a Terzaghi mō te tātai i te kaha kawe mutunga o te oneone _q_f e kī ana

1. Mō te tūāpapa taketake ā-āhua rīpene

qf = cNc + γ1 DfNq + 0,5 γ2 BNγ  

kei reira ko te c ko te whakakotahitanga o te oneone

γ1 te taumahatanga ā-rōrahi o te oneone i runga ake i te papa o te tūāpapa

Df te hōhonu o te tūāpapa i raro i te mata o te whenua ki te papa tūāpapa

γ2 te taumaha rōrahi o te oneone i raro iho i te papa tūāpapa

B te whānui o te tūāpapa taketake.

Ko Nc, Nq, Nγ ngā āhuatanga kawe, e whakawhirinaki ana ki te koki o te waku ā-roto o te oneone; ko ngā tauira mō ēnei āhuatanga e hoatu ana i raro nei mā ngā whakaaturanga e whai ake nei:

Nq he tauwehe nā te taumaha o te paparanga oneone taha tae noa ki te hōhonutanga turanga: Nq = tg2 (45° + ϕ/2) eπ tg_ϕ_

Nc ko te āhuatanga nā te kōtahitanga: Nc = (Nq – 1) ctg_ϕ_

Ko Nγ te tauwehe nā te taumaha ake o te kōtī oneone kei raro i te papa tūāpapa, arā, i raro i te whānui o te papa AB. E taunakitia ana e Brinch Hansen te uara tata o tēnei tauwehe: Nγ ≈ 1,8 (Nq – 1) tg_ϕ_

Sl. 4. Te tohatoha o ngā ahotea ka riro i te oneone i raro i te kawenga poutū, pokapū hoki o te tūāpapa

Nā te iti o te rerekētanga o te taumahatanga kōrahi o te oneone ka whāia nuitia γ1= γ2= γ. E ai ki te whārite o mua, e whakawhirinaki ana te kaha kawe o te oneone (sl. 4) ki: te piringa o te oneone taketake c, te utaina o te oneone i te taha o te tūāpapa γ1 D_F, me te taumaha ake o te oneone o te kāri retireti kaha o te whānui B.

Heoi, ahakoa he ōrite te tohatoha o ngā taumahatanga e whiwhia ana e te oneone nā te pānga o te piringa c me te hōhonutanga tūāpapa Df puta noa i te whānui katoa, arā he tapawhā, ko te tohatoha o ngā taumahatanga e whiwhia ana e te oneone nā te pānga o te whānui B he āhua tapatoru, arā ka riro ngā taumahatanga nui rawa i waenganui o te tūāpapa, ka heke atu ki ngā tapa, ka ōrite ki te kore.

Fig. 5. Kaupapa o te tauwehe kawe i runga i te koki o te waku ā-roto o te oneone e ai ki a Terzaghi

Mō ngā uara rerekē o te koki mai i te 0 ki te 40°, i whakaritea e Terzaghi he hoahoa mō ngā taupū kaha kawe (whaka. 5). Heoi anō, ko ngā taupū kaha kawe Nc, Nq me Nγ (ngā rārangi pū i te whakaahua 5) ka taea anake te tango i te take o te oneone kōmāmā, kōpāpā hoki. Ki te kōmāmā te oneone, ki te kaha rānei tōna kōpeketanga, me tango ngā taupū kaha kawe N’c, N’q me N’γ (ngā rārangi whatu i te wh. 5), e hoatu ana i ngā uara 2/3 o te ātete waku. Hei tāpiri, i tēnei take me tango ngā uara 2/3 o te tōpūnga c kua riro mā te taiwhanga, kia pērā ai tā tātou whai qf = 2/3 cN’c + γ1 DfN’q + 0,5 γ2 BN’γ.

2. Mō te tūāpapa takitahi āhua tapawhā

qf = 2/3 (1+0,3 B/L) cN’c + γ1 DfN’q + 0,5 γ2 BN’γ  kei reira ko L te roa o te takapau tūāpapa

3. Mo te tūāpapa oneone āhua tapawhā

qf = 2/3 1,3 cN’c + γ1 DfN’q + 0,4 γ2 BN’γ  

4. Mō te tūāpapa porowhita

qf = 2/3 1,3 cN’c + γ1 DfN’q + 0,6 γ2 rN’γ  kei reira ko r te pūtoro o te papa tūāpapa.

Mō te tātai i te kawenga oneone e whakaaetia ana ka tangohia te taupū haumaru F: qa = qf/F. Ko te uara o te taupū haumaru kei waenganui i 2 me 3 e ai ki ngā āhuatanga o te oneone me te kawenga.

Te whakamahinga o ngā tauira pāngarau

Ko te whakamahi i ngā tauira pāngarau hei whakatau i te kawenga whakaaetia o te oneone e hiahiatia ana kia mōhio ki ngā āhuatanga geomata o te oneone, arā, te here-piri me te waku ā-roto i te hōhonutanga o te whakatūnga me te taumaha rōrahi o te oneone kei runga ake, kei raro iho hoki i te papa tūāpapa. Mēnā kei raro iho te oneone tūāpapa i te taumata o te wai whenua, me whai whakaaro anō ki te hiki i te kōwhiringa i te whakatau i te taumaha rōrahi o te oneone.

Mō ngā taumahatanga oneone nui ake me ngā hanga nui ake, ina tino whakamahia katoatia te uara kua whiwhia o te kawenga oneone e whakaaetia ana i runga i ngā tauira pāngarau, me tautoko te tātai i te kaha kawe o te oneone e tētahi tātaitanga o te heke. Ka whakaaetia te kaha kawe kua tātaihia o te oneone anake mēnā kua puta i te tātai he heke iti iho i te mea e whakaaetia ana mō taua momo hanga. Ki te mea kua puta i te tātai he heke nui ake i te mea e whakaaetia ana, kāore te uara kua tātaihia o te kawenga oneone e whakaaetia ana mā ngā tauira tātai e whakaaetia, engari me whakarerekē te tikanga whakatū tūāpapa kia iti ake ai te heke, i roto i ngā here o te heke e whakaaetia ana mō taua hanganga.

Whaka. 6. Te hōhonutanga whai hua o te tūāpapa D__f

I roto i ngā tauira pāngarau mō te whakatau i te kaha kawe mutunga o te oneone kāore i whai whakaaro ki te waku o te takai o te tūāpapa, ahakoa ka whai wāhi hoki taua mea hei ātete ki te pānga o te utanga, mēnā ka pā pū te tūāpapa ki te oneone i ngā taha. Kāore e tika kia whai whakaaro ki te ātete waku o te takai, nā te mea kei ngā pou anake ka akiakina ki te oneone te waku takai tūturu, ā, i ngā papa tūāpapa he iti rawa te waku o te takai, nā te mea ka hangaia ngā papa ki ngā kōhao kua keria kē i mua.

Ko te whakamahi i ngā tauira pāngarau kāore e whai whakaaro ki te āhua o te tūāpapa ka tuku i ngā hua tata rawa mō ngā tūāpapa ā-rīpene, arā, ina neke atu te roa o te tūāpapa i te rua wā o tōna whānui. Kua whakaūngia e ngā whakamātau, mō ngā pūtake tūāpapa ā-tapawhā, ā-porowhita rānei, ka puta te whati i te kawenga tāhūhū e nui ake ana mā te 10-30% i tā te tātai pāngarau. Ko ngā pūtake ā-toru e iti ake ai te kaha kawe i tō te rīpene, ā, ko te iti rawa o te kaha kawe ka riro i ngā pūtake ā-whakatārere, mēnā kāore i whakakīa.

Ka tātaihia te hōhonutanga tūāpapa Df hei hōhonutanga whaihua o te tūāpapa i raro iho i te whenua o te turanga o te tūāpapa ki raro ki te papa tūāpapa (Whaka. 6). Mō ngā tūāpapa i raro i ngā rūma kei raro i te whenua, he rerekē te hōhonutanga tūāpapa whaihua Df i te hōhonutanga tūāpapa i raro hoki i te mata o te whenua. I aua āhuatanga, mō te tātai i te kawenga tepe me te kawenga whakaaetia o te oneone me whakamahi tonu te Df, nā te mea kei runga ake i te whenua o te turanga he hau, ā, kāore taua hau e whakahē ana i te kōpeketanga taha o te oneone i raro i te pānga o te kawenga tūāpapa P.