Ƙaddamar da haɗin kai da kusurwar rikici na ciki

A yau, Savo Kusić yana mai da hankali kan gilashin katako, itace-aluminum Taga, Taga na al’ada, kofa da buƙatun magana. Wannan rubutun ya kasance azaman ma’ajiyar kayan tarihi kuma ba tayin don gwajin dakin gwaje-gwaje ba, ƙirar geotechnical ko aikin ƙasa.

Akwai hanyoyi da yawa na tantance abubuwan juriyar ƙasa na ciki, haɗin kai da kusurwar gogayya ta ciki ta amfani da gwaje-gwajen dakin gwaje-gwaje, daga cikinsu gwajin direct shear da gwajin triaxial compression sune suka fi shahara.

Gwajin shear kai tsaye

Ana yin gwajin akan na’ura mai nau’in nau’in A rectangular. Casagrandea ko a kan madauwari na’ura na nau’in Hvorsleva. Za mu kwatanta gwaji tare da na’urar sashin rectangular, wanda aka fi amfani dashi. A cikin lokuta biyu, ana yin gwajin tare da samfurin da ba a damu ba, ko kuma tare da samfurin damuwa a wurin yawan amfanin ƙasa, wanda gwajin yana da ƙimar kwatancen.

Na’ura don yanke kai tsaye na sashin rectangular (fig.1)

Sl.1 Sashe na na’urar sarrafa kai tsaye ta Casagrande

Na’urar ta ƙunshi sassa biyu, babba da ƙananan firam, inda ƙananan ke tsaye, yayin da babba kuma mai motsi ne kuma za’a iya motsa shi a ƙasa ƙarƙashin rinjayar ƙarfin kwance Z, wanda ke aiki akan layin lamba na sama da ƙananan firam.

Ana sanya samfurin ƙasa a cikin zobe na rectangular karfe, mafi girman girman100×100×30 mm, ko kuma waɗanda girman lokacin da aka goge daidai. Ana sanya duwatsu masu tacewa a sama da kasa na samfurin, sa’an nan kuma a sanya komai a cikin zoben na’urar, sannan a cika da ruwa. Ana sanya na’urar don lodi a tsaye akan samfurin. Dutsen tacewa na sama yana haɗa da tsarin ɗaukar nauyin samfurin a tsaye, yayin da ƙananan yana haɗa da tashoshi na ruwa, ta hanyar abin da za a iya ajiye samfurin a cikin cikakken yanayin yayin gwajin, don cire haɗin kai na fili.

Don ware juzu’i akan wuraren tuntuɓar da ke tsakanin firam na sama da na ƙasa, akwai na’urori tare da firam na sama da aka zazzage, ta hanyar abin da firam ɗin babba ke motsawa ƙarƙashin tasirin juzu’i na kwance. Bugu da kari, da lamba saman firam na sama da ƙananan suna mai rufi da man jelly. Ana haɗa ƙarin a cikin na’urar2comparator don yin rijistar nakasu a tsaye da a kwance.

Gudanar da gwaje-gwajen shear kai tsaye

Akwai galibi2nau’ikan gwajin shear kai tsaye: fast da slow gwajin. Gwajin quick ya ƙunshi loda samfurin tare da wani matsi na tsaye, wanda yawanci yayi yawa0,50;1,0;2,0;3,0kuma4,0kp/cm2, jira ƙarfafawa, wanda ake zaton an samu idan an sami raguwa a lokacin lokacin.24hours Δh ≤0,02 mm, sa’an nan kuma a yi amfani da karfi a kwance Z, mai girma,1/20ko1/40wani ɓangare na ƙarfin tsaye P, wanda ke ƙaruwa kowane minti daya da ƙimar guda har ƙasa ta karye. A lokacin aikace-aikacen ƙarfi na kwance a kwance, ana lura da yanayin motsi na firam na sama koyaushe ta hanyar karantawa akan kwatancen kuma ana yin rikodin nakasar kwance a cikin log ɗin nan da nan kafin kowane sabon kaya. Lokacin, wanda mai kwatancen ke nuna motsi kwatsam, ana ɗaukarsa azaman rushewar ƙasa.

Ana amfani da gwajin sauri ga ƙasan yumbu, wanda haɓakar yanayin halitta a ƙarƙashin sabon nauyi yana jinkirin kuma yayi daidai da wannan hanyar yin gwajin.

Slow kamar yadda yake a baya tare da bambanci kawai cewa ƙarfin juzu’i na kwance yana ƙaruwa cikin lokaci mai tsawo, wanda zai iya zama 2, 5 da 15 mminutes ko kuma har sai an ƙarfafa, watau har sai da nakasar kwance ta zama gaba ɗaya. Ana lura da tsarin ƙarfafawa a ƙarƙashin tasirin ƙarfin kwance akan mai kwatanta 9 (fig. 1).

An yi gwajin jinkirin gwajin a cikin ƙasa mai yashi ko ƙura, inda idan yanayin ya karu da ƙarfi a kwance a cikin ɗan gajeren lokaci, raguwar samfurin a cikin na’urar zai yi sauri saboda tasirin ruwa mai tsanani a cikin pores, wanda ba zai dace da tsarin halitta ba. Sabili da haka, tazarar lokaci yana ƙaruwa tare da ƙarancin ƙarancin ƙarancin ƙasa wanda ba a ɗaure ba, don ba da damar daidaita matsa lamba na ruwa a cikin ƙasa tare da matsa lamba na waje. Ana samun wannan daidaitawar ta hanyar barin isasshen lokaci a ƙarƙashin tasirin kowane matakin ɗaukar nauyi a kwance, ta yadda ruwan da ya wuce gona da iri a cikin ramuka ana matse shi ta hanyar dutsen tacewa.

Baya ga gwaje-gwajen da aka ambata, a wasu lokuta ana yin gwajin gaggawa ba tare da ƙarfafawa ba a ƙarƙashin kaya a tsaye, watau ana amfani da ƙarfin jujjuyawar a kwance nan da nan bayan shigar da samfurin a cikin na’urar kuma a loda shi tare da kaya a tsaye. Duk da haka, ana amfani da wannan hanyar kisa a ƙarƙashin yanayi na musamman, kamar yanayin da aka yi da ƙasa mai yumbu, wanda aka loda shi nan da nan bayan an dasa shi ba tare da annashuwa ba.

Ƙaddamar da kusurwar rikici na ciki da haɗin kai

Bisa ga sakamakon gwajin, an ƙididdige yawan damuwa

τ=Z/A a kp/cm²,

wanda aka samu daga karfin shear Z a cikin kp a lokacin rashin nasara da yanki giciye na samfurin A a cm². Ana yin kwarewa da3ku4na’ura da aka loda tare da matsi na al’ada daban-daban σ=P/A a kp/cm² inda P shine nauyin samfurin a tsaye a kp. Ana ɗaukar ƙimar matsi na yau da kullun:1,0;2,0;3,0kuma4,0kp/cm².

Sl.2. Tsarin nakasu a kwance

Dangane da zane-zane na abubuwan haɗin gwiwa na ciki, ana samun nau’ikan zane-zane guda biyu1da kuma zane na nakasu a kwance (fig.2).

Ana samun zane na nakasar kwance ta hanyar yin amfani da ƙaura a kwance ΔL a cikin mm na babban firam na na’urar zuwa ƙasan ɗaya akan axis abscissa, wanda aka samu ta hanyar karanta mai kwatanta.9, kuma akan ordinate axis madaidaicin damuwa mai ƙarfi τ a cikin kp/cm² (fig.2).

Dangane da ƙaddamar da ƙasa, ana samun zane1don m da zane2don sako-sako da abu.

Don ƙaƙƙarfan abu, damuwa mai ƙarfi τ yana ƙaruwa da farko a hankali dangane da ƙaurawar kwance ΔL har zuwa iyakar ƙimar P, sannan a hankali a hankali, yayin da yanayin zane.1yana ƙaruwa kuma ya kai matsakaicin tsayin B, bayan haka zane yana raguwa don wani tsayin tsayi, don a ƙarshe ya kai ga kwararar kwance. Yankin hawan layi madaidaiciya na zane-zane na nakasar kwance, wanda yawan karuwar damuwa ya yi daidai da karuwar lalacewa, ana zaton shine yankin nakasar nakasa. Bayan iyakar P, karuwa a cikin damuwa na raguwa yana raguwa bisa ga karuwar lalacewa ΔL har zuwa mafi girman maki B na zane. A cikin wannan yanki, kayan yana fara “zubawa” kuma an karɓa a matsayin yanki na lalata filastik. Matsayi mafi girma na zanen B1yana wakiltar matsakaicin matsakaicin ƙarfin ƙarfi max τ, kuma ana ɗauka cewa karyewar ƙasa yana faruwa a wannan lokacin, watau wannan batu B shine wurin karyewa. Bayan batu B, kayan yana cikin yanayin ruwa, ƙarfin raguwa ya ragu, kuma an ɗauka cewa a cikin wannan yanki, inda haɗin tsakanin sassan ya karye, akwai juriya na zamewa kawai wanda ke adawa da ƙarfin ƙarfin kwance. Point G inda zane yake1wucewa a kwance ana ɗaukarsa azaman iyakar zamiya.

Ƙarfin shear a iyakar gazawar B ana kiransa ƙarfin shear ko pure shear ƙarfi τf, yayin da ƙarfin shear a iyakar amfanin G ana kiransa zamewar ƙarfi τg.

Don kayan sako-sako, zanen ƙaura a kwance yana da yanki na roba tare da iyakacin ƙimar P, amma ƙasa shine yanki na filastik har zuwa iyakar zamewar G, watau matsakaicin matsananciyar ƙarfi yana daidai da ƙarfin iyaka, zamewa (τ = τg), bayan haka yanayin ruwa na kayan.

Sl.3. _Tsarin shear, a) don ƙasa mai daidaituwa, b) don ƙasa mara daidaituwa.

Ana samun zanen shear lokacin da aka yi amfani da matsa lamba na al’ada σ a cikin kp/cm zuwa axis abscissa2, kuma akan ordinate axis madaidaicin ƙarfin shear τf a kp/cm2, inda aka yi amfani da waɗannan ƙimar duka a cikin ma’auni ɗaya (fig.3). Tun lokacin da ƙarfin ƙarfi τf na ƙasa yana ƙaruwa tare da matsa lamba na al’ada σ, zai yi don matsi daban-daban σ1 sami maki A, B, C, da D, waɗanda ke wakiltar madaidaitan ƙarfin juzu’i.

Don samun maki ɗaya A, B, C da D akan zane3don kasa mai daidaituwa (Fig.3a), an karɓi ƙarfin zamewa _τ_g. Duk da haka, a cikin yanayin ƙasa mai yumbu, kayan ya fara gudana tun kafin iyakar zamiya G ya kai, kuma akwai hali don ɗaukar ƙarfin ƙarfi a iyakar ƙimar P don ƙayyade haɗin kai c da kusurwar haɗin ciki na ƙasa, amma tun da yake yana da ƙananan ƙananan, ƙarfin ƙarfi wanda nakasar ΔL a kan zanen da aka ɗauka sau da yawa ana amfani dashi.2sau biyu girma fiye da nakasar a matakin da ya gabata na lodi a cikin na’urar. Wannan ƙarfin yana wani wuri tsakanin iyakar P da B, wato, G (fig.2).

Haɗa maki A, B, C da D akan zane 76a yana ba da zane mai shear, wanda shine madaidaiciyar layi a cikin gwaji mai nasara. Ta hanyar ƙaddamar da zane zuwa tsaka-tsaki tare da axis mai daidaitawa, don σ = 0, an samo shi bisa tsarin Coulomb τf = c+σ tgϕ cewa τf = c = haɗin ƙasa, yayin da gangaren zanen zuwa kusurwa na ciki yana ba da kusurwar ciki. Ta hanyar tsawaita zane-zane a gefe na ordinate axis, ana samun damuwa saboda haɗin kai pk akan abscissa axis, lokacin da aka bayyana girman haɗin kai c a matsayin daidai da juriya na juriya:

c = pk tgϕ, daga ina pk = c/tgϕ

Don ƙasa mara daidaituwa, kamar yashi, zane a cikin fig. 3b, wanda ke wucewa ta asalin haɗin gwiwa, tunda ga σ = 0 muna samun τ = 0. Duk da haka, idan yashi yana da kyau kuma ya jike, zane mai kama da wanda yake cikin fig. 3a, tare da ƙaramin haɗin kai c, wanda ke wakiltar haɗin kai na bayyane. A wannan yanayin, damuwa pk akan tsawan abscissa mai tsawo a ɗayan gefen asalin haɗin gwiwa yana wakiltar damuwa na capillary.

Ya kamata a lura da cewa ƙayyadaddun ƙayyadaddun ƙasa da jujjuyawa ta hanyar gwajin kai tsaye yana da lahani da yawa, mafi mahimmancin su shine gazawar ƙasa tana faruwa akan wani yanki da aka riga aka ƙaddara kuma ba akan ƙasan ƙarancin juriya ba, cewa yayin yanke samfurin a cikin na’urar, an rage girman saman ƙasa saboda motsi na sama da na sama. za a iya sa ido kawai a kan ɗan gajeren tsayi, ta yadda juriya mai zamiya fiye da iyaka ba zai iya sarrafa karaya ba har zuwa isasshen adadin, musamman ma a cikin ƙasa mai laushi lokacin da nakasar da aka yi a lokacin shearing suna da yawa, da dai sauransu

Triaxial matsawa gwajin

Ana yin gwajin ne akan na’urar triaxial, wacce ke da zane daban-daban, amma dukkansu sun dogara ne akan ka’ida guda, wanda shine kamar haka. Samfurin da ba shi da damuwa a cikin nau’i na abin nadi an sanya shi a tsaye a kan tsayawar kuma yana nunawa zuwa matsa lamba na gefe na yawan ruwa daga kowane bangare sannan kuma zuwa matsa lamba na tsaye, wanda a hankali ya karu, har sai an samu karyewar samfurin a saman mafi ƙarancin juriya. Dangane da ƙarfin juzu’i a lokacin hutu, ana ƙididdige haɗin kai da kusurwar haɗin ciki na ƙasa.

Bayanin na’urar triaxial

Sl.4. Triaxial apparatus

Na’urar Triaxial (Fig.4) ya ƙunshi ƙananan ɓangaren tushe na ɗakin, wanda samfurin ya tsaya a kan shi, kuma a cikin ɓangaren sama na piston don ɗaukar nauyin samfurin a tsaye da farantin da ke rufe ɗakin. Mafi yawan ma’aunin samfurin shine diamita ϕ=36 mm, tsawo h=2,2-2,5_ϕ_. Diamita na ɗakin shine D=135mm, tsawo H =180 mm. Ƙaƙƙarfan bututu K yana farawa daga tsakiyar tashar samfurin1don zubar da samfurin daga ƙasa, wanda ke karɓar ruwa daga samfurin ta hanyar faranti mai laushi kuma ya zubar da shi a waje da ɗakin a cikin bututun gilashin C a tsaye.1. Idan an yi gwajin ba tare da zubar da samfurin ba, wannan tashar tana aiki don auna matsa lamba na ruwa a cikin pores. Akwai tashar K a cikin ginin tagulla na ɗakin2don samar da ruwa mai yawa don cika ɗakin da kuma haifar da matsa lamba na gefe a cikin ɗakin a kan samfurin.

Ta saman farantin ɗakin yana wucewa ta hannun fistan don loda samfurin. Samfurin da ke cikin ɗakin yana kewaye da murfin roba, wanda aka shimfiɗa a ƙarshen duka kuma an haɗa shi da piston da tushe ta hanyar zoben roba. A tsakiyar fistan akwai tashar K3don zubar da samfurin daga gefen babba.

An rufe gefuna na ɗakin da hermetically tare da silinda Plexiglas wanda aka kafa a saman faranti na sama da na ƙasa na ɗakin ta zoben roba.

An sanya ɗakin a kan tushe mai ƙarfi. Ana yin ɗorawa na al’ada na samfurin ta hanyar lever tare da ma’auni, rabon wanda yawanci shine 1: 10. Tsarin don cimma matsa lamba na gefe akan samfurin a cikin ɗakin ya ƙunshi kwalban da ruwa mai yawa B, wanda aka kawo cikin ɗakin ta hanyar bututu, manometer don auna ma’aunin iska da kwalban da aka matsa. Ana sanya comparator a sama da fistan don loda samfurin don auna daidaiton samfurin a ƙarƙashin kaya.

Za’a iya daidaita matsi na gefe na yawan ruwa a cikin ɗakin da aka so ta amfani da karfin iska a cikin kwalban B, ta hanyar bawuloli V1 da V2. Wannan matsa lamba yana haifar da damuwa a kwance a cikin samfurin σ2 da σ3, wanda saboda sashin madauwari na samfurin an daidaita σ2 = σ3.

Za a iya distilled ruwa ko mai, wanda aka fi so don mafi kyau sealing, domin ruwa zai iya wucewa ta cikin screws. A ƙarƙashin rinjayar matsa lamba na iska a cikin kwalban B, yawan ruwa ya cika ɗakin har zuwa bawul V6, wanda ya rufe. A tsaye lodi na samfurin P, wanda aka canjawa wuri kusan frictionlessly zuwa samfurin ta hanyar piston rike, raba ta giciye-section yanki na samfurin A ya ba da a tsaye danniya σ1 = P/A

Ana aiwatar da gwajin matsawa na triaxial

Don samfurin gwajin, ana sarrafa shi a cikin na’urori daban-daban, ta yadda za a samu rowa mai diamita 36 mm, tsayin 78 mm ko 90 mm, a kan sanya duwatsu masu tacewa daga sama da kasa sannan a sanya membrane na roba. Sa’an nan kuma ana sanya samfurin tare da duwatsu masu tacewa a kan tsayawar da ke cikin ɗakin, iyakar, ƙullun roba a kan madaidaicin da piston mai kaya da kuma kulla da zoben roba. Bisa ga al’adar wasu dakunan gwaje-gwaje, irin su Farfesa Skempton a London, zubar da samfurin a cikin ɗakin a lokacin gwajin yana da sauri ta hanyar rufe gefen samfurin tare da takarda mai tacewa, wanda ake ajiyewa kafin a cire murfin roba. Lokacin da aka shigar da samfurin a cikin na’urar kuma an gyara Plexiglas cylinder a cikin faranti na sama da na ƙasa, yana yiwuwa a yi gwaje-gwaje, wanda za’a iya yin ta hanyoyi da yawa, kamar haka:

1. Gwajin da ba a zubar da ruwa ba. A cikin wadannan gwaje-gwajen, ba a ba da izinin zubar da samfurin a lokacin da ake yin gwajin na gefe da na tsaye ba, yayin da bawuloli V4 da V5 ke rufe.

2. Gwaje-gwajen marasa ruwa tare da ƙarfafawa. A lokacin aikace-aikacen matsa lamba na gefe, ana zubar da samfurin (bawuloli V4 da V5 suna buɗewa), yayin da lokacin aikace-aikacen matsa lamba na tsaye, ba a yarda da magudanar ruwa (V4 da V5 an rufe)

3_) Samfurori da aka zube_. Ana zubar da samfurin na tsawon lokacin gwajin (valves V4 da V5 suna buɗewa), don haka cikakken ƙarfafawa yana faruwa kuma ba a haifar da ruwa mai damuwa a cikin pores yayin aikace-aikacen matsa lamba na tsaye σ1. Wannan gwajin yana ɗaukar lokaci mai tsawo, musamman tare da ƙasa mara kyau, saboda a tsaye loading σ1 dole ne a yi shi a cikin adadi mai yawa na ƙananan matakai kuma dole ne a jira ƙarfafawa a kowane mataki. Bugu da ƙari, ana iya yin gwajin da aka ambata tare da saturated da partially saturated samples_._

Idan akai la’akari da yiwuwar da aka ambata a sama, ana iya yin gwajin matsawa na triaxial a cikin bambance-bambancen daban-daban kuma a daidaita su bisa ga nau’in ƙasa ƙarƙashin yanayin kaya.

Na’urorin, hanyoyin, raka’a, dabi’u da tsarin da aka bayyana ana watsa su daga tushen tarihi. Rubutun ba binciken ilimin geotechnical ba ne, ka’idar dakin gwaje-gwaje, aikin tushe, tabbacin kwanciyar hankali ko shirin hakowa. Zaɓin samfurin da hanyar gwaji, yanayin magudanar ruwa da ƙarfafawa, ruwa na ƙasa, tsarin mulki, tasirin girgizar ƙasa da amincin hakowa dole ne a ƙayyade don ƙayyadaddun ƙasa da kayan aiki, bisa ga ƙa’idodin yanzu, tare da dakin gwaje-gwajen da ya dace da ƙwararrun ƙwararrun geotechnical masu izini.