** Muhimmin bayanin kula na ƙwararru:** Wannan labarin bita ne na ilimi na tarihi kuma ba binciken ilimin kimiyyar ƙasa bane, ingantacciyar ƙa’idar dakin gwaje-gwaje, lissafin tushe ko umarnin aiwatarwa. Sharuɗɗa na asali, hanyoyin, raka’a na ma’auni, ƙima, rarrabuwa da nassoshi zuwa “dokokinmu” an canza su ba tare da bincika ƙa’idodi da ƙa’idodi masu dacewa ba. Soil testing, choice of method, interpretation of results and design decisions must be carried out by authorized geotechnical experts and the appropriate laboratory for a specific facility and location.
Batun damtse ƙasa baya cikin sabon tayin jama’a na Savo Kusić. Mahimmancin samarwa na yanzu ya ƙunshi gilashin katako, itace-aluminum Taga da kofofin al’ada. Don takamaiman aikin taga ko kofa, zaku iya aika buƙatar magana.
Tushen gwajin oedometer
Matsakaicin ƙasa ana ƙaddara ta hanyar gwajin matsawa tare da hana faɗaɗa a gefe, wanda kuma ake kira gwajin oedometer ko gwajin ƙarfafawa.
Ana yin gwajin tare da samfurori marasa damuwa, kuma a wasu lokuta tare da damuwa. A cikin shari’ar farko, ana ɗaukar samfurin gwajin ta danna zoben ƙarfe a cikin samfurin da ya fi girma, wanda ba shi da damuwa, sannan a ciyar da shi a cikin na’urar tare da zobe bayan yanke samfurin da ya wuce kima kuma ya daidaita samansa tare da gefuna na Silinda. A cikin akwati na biyu, an cika zobe tare da samfurin a cikin yanayi mai dacewa a wurin samar da amfanin gona kuma a cikin wannan jiha an shigar da shi a cikin oedometer.
Ana yin gwajin ne ta hanyar amfani da na’urar da Terzaghi ya fara ginawa da ake kira Oedometer. A yau, akwai gine-gine daban-daban na wannan na’ura, amma duk sun dogara ne akan ka’ida ɗaya, suna gwada matsi na samfurin ƙasa a ƙarƙashin kaya tare da hana haɓakawa ta gefe.
Oedometer: bayanin na’urar
Sl.1. Edometer
Oedometer ya ƙunshi silinda na ƙarfe wanda samfurin yake tsakanin duwatsu masu tacewa (fig.1). Ana gabatar da samfurin a cikin na’urar a cikin zoben ƙarfe na diamita7-10 cm, tsawo1-4 cm. Ana ɗaukar nauyin P zuwa samfurin ta dutsen tacewa na sama. A ƙasan ƙananan dutsen tacewa, akwai tashoshi a cikin ƙasan silinda don zubar da ruwa daga samfurin a cikin bututun capillary, da kuma samar da ruwa. Tun da matsawa na samfurin da aka yi a kudi na pores, saboda m ƙasa barbashi da ruwa a cikin pores ne a zahiri m, shi wajibi ne a lokacin gwajin don tabbatar da fitar da ruwa daga cikin samfurin, wanda aka yi ta hanyar wani tace dutse, tashar da capillary tube.
A gefen hagu na na’urar akwai bututun samar da ruwa tare da famfo a gaban silinda, yayin da bututun capillary yana gefen dama, tare da famfo bayan silinda. Har ila yau, bututun capillary yana yin aiki don tantance ƙayyadaddun ƙarancin ƙasa k.
Gwaji
Lokacin da aka sanya samfurin a cikin silinda kuma an haɗa na’urar, rufe fam ɗin hagu, samar da ruwa, kuma buɗe fam ɗin dama, don ruwa ya gudana cikin bututun capillary. Sa’an nan kuma an kusanci nauyin samfurin, wanda aka yi amfani da shi a hankali. Yawancin kaya masu zuwa ana amfani da su:0,50;1,00;2,00;4,00;6,00kp/cm2da kara har zuwa matsakaicin nauyin ƙasa da ake tsammani a ƙarƙashin ginin, gabaɗaya har zuwa10kp/cm2, kuma tare da madatsun ruwa zai iya zama ma fiye20kp/cm2. A kowane matakin lodi, a daidai lokacin da ake aiwatar da shi, ana fara agogon gudu kuma a wasu tazarar lokaci15“,30“,1’,2’,5’,15’,45’,2h5h24h, sannan duk gaba24h, har sai an ƙarfafa samfurin a ƙarƙashin wannan matakin nauyi, daidaitaccen daidaitawa a cikin dubunnan millimita ana karantawa akan kwatancen kuma an rubuta shi a cikin rikodin. Ana ɗauka cewa an samu haɓakawa idan ƙaddamarwar samfurin shine Δh ≤0,02 mmdomin lokacin24awa. Bayan da aka samu ƙarfafawa, ana amfani da nauyin nauyi na gaba kuma ana maimaita aikin gaba ɗaya a cikin hanyar da sauransu har zuwa matakin karshe na kaya.
Gwajin haɓakawa tare da hana haɓakar haɓakawa na gefe ana yin shi tare da lodi da saukewa, don sanin ƙayyadaddun kaddarorin ƙasa. Bayan mun loda samfurin zuwa wani mataki, muna sauke shi tare da sannu a hankali kamar yadda muka loda shi. Yawancin lokaci ana yin agaji daga baya2,0kp/cm2,4,0kp/cm2kuma6,0kp/cm2.
A matsayinka na mai mulki, ana yin gwajin tare da samfurin a ƙarƙashin ruwa, wanda aka gudanar a kan bututun gilashin hagu a tsayin saman saman samfurin a cikin na’urar. Gwajin damtsewar samfurin a gaban ruwa ana yin shi ne saboda wannan dalili, saboda gwajin yana ɗaukar lokaci mai tsawo kuma samfurin yana bushewa a wannan lokacin, wanda sakamakon haka ƙarfin samfurin zai zama ƙasa da ainihin matsi na ƙasa a yanayin yanayin ɗanɗanonta. Bugu da kari, damshin da ke cikin kasa na iya zama sama da yadda yake a lokacin da ake yin samfur, musamman idan matakin ruwan karkashin kasa ya tashi, wanda zai iya haifar da wani gagarumin sabani daga ainihin matsi na kasar a lokacin babban tebur na ruwa.
An ƙirƙira sakamakon gwajin akan nau’ikan zane-zane guda uku, wato zanen matsawa dangi, zane mai canzawa porosity da zane na lokaci.
Tsarin matsi na dangi
Ana samun wannan zane lokacin da aka yi amfani da matsa lamba na al’ada akan samfurin akan abscissa axis σ = P/A, inda P shine nauyin da ke aiki akan samfurin ta hanyar dutsen tacewa na sama a kp / cm2, A yankin giciye na samfurin a cikin na’urar, kuma a kan madaidaicin madaidaicin matsawa dangi Δh/ h inda Δh shine daidaitawar samfurin a ƙarƙashin kaya Δσ yayin ƙarfafawa, h tsayin samfurin kafin ɗauka (fig.2).
Sl.2. Tsarin matsi na dangi
A lokacin lodawa, ana samun diagram na matsawa na farko a..
Lokacin zazzagewa, idan aka sha ruwa ba tare da an hana shi ba, ta yadda samfurin ya kasance a karkashin ruwa yayin sauke kaya, sai ya koma yadda yake, watau kumburi. Duk da haka, samfurin baya komawa matsayinsa na farko, wanda ke nufin cewa ya sami nakasar filastik (na dindindin) ban da na roba. Saboda haka, a wannan yanayin, ana samun zane mai kumburi b yayin sauke kaya. Koyaya, idan an yi gwajin ba tare da samun ruwa ba, maimakon zane mai kumburi, abin da ake kira diagram of elasticity.
Idan samfurin ya sake lodawa bayan an sauke shi, ana samun zane na matsawa na biyu c. Zane mai kumburi da zane na matsawa na biyu c suna samar da madauki mai tsauri tsakanin su. A cikin yumbu, madaukai na hysteresis suna da mahimmanci kuma saboda haka nakasawa a cikin yanki na kumburi da matsawa na biyu (hotunan b da c) ba a la’akari da su na roba, amma masu juyawa, tun da ba su dace da kaya ba bisa ga dokar Hooke. Nakasar da aka samu a wajen matsawa na farko (hoto a) a bangaren da ba su dawo ba na dindindin ne (ba za a iya jurewa ba).
Ƙasa matsa lamba module
Daga zane na matsawa dangi, muna samun bisa ga dokar Hooke daidai da Jung’s modulus na elasticity E don kayan roba, yanayin matsawa na ƙasa Ms
Ms = Δσ / (Δh/h) [kp/cm2],
in inda Δσ shine haɓakar kaya, Δh/ h shine matsi na dangi daidai, wanda aka ɗauka daga zane na farko na matsawa a (fig. 2).
Module na damfara na ƙasa Ms ya bambanta da yanayin elasticity E na kayan roba, saboda Ms ba koyaushe bane ga abu ɗaya kuma iri ɗaya amma yana canzawa kuma yana ƙaruwa da nauyin al’ada σ. Don haka, ana iya bayar da ƙayyadaddun ƙayyadaddun ƙima na matsawa modules Ms don kunkuntar tazara ɗaya na nauyin ƙasa ta al’ada Δσ. Idan darajar modul Ms ta fi girma, damtsen ƙasa yana ƙasa da kuma akasin haka. Dangane da ka’idodin kafuwar mu, ana ɗaukar ma’auni mai zuwa don yanayin damtse ƙasa a cikin yanayin yanayinta:
Ana ɗaukar rabe-raben da ke ƙasa daga ainihin rubutun, gami da maimaita tazarar100-400kp/cm2. Ba a bincika ko daidaita shi da ƙa’idodi na yanzu ba.
Ms =0-20kp/cm2kasa mai matsa lamba
Ms =20-50kp/cm2ƙasa mai matsewa sosai
Ms =50-100kp/cm2ƙasa mai matsakaita
Ms =100-400kp/cm2ƙasa mai matsewa
Ms =100-400kp/cm2ƙasa mai matsawa kaɗan
Ms =400-1000kp/cm2ƙasa mai matsawa kaɗan
_Ms_1000 kp/cm2ƙasa mai matsawa kadan.
Modulus na elasticity na ƙasa
Hakazalika, muna samun ma’aunin elasticity na ƙasa E:
E = Δσ / (Δh/ h) \ [kp/cm2],
inda aka ɗauko ƙarar matsawa Δh/ h daga ƙirar elasticity na ƙasa don daidaitaccen matsa lamba na al’ada Δσ.
Ƙaƙwalwar ƙasa ta al’ada kuma mai ƙarfi
Sl.3. Tsarin canji na porosity coefficient na damuwa ƙasa samfurin
Idan muka yi gwajin oedometer tare da samfurin damuwa, wanda muka shiga cikin na’urar a wurin samar da amfanin gona, kuma muka tsara sakamakon gwajin akan zane na canji a cikin coefficient na porosity e dangane da matsa lamba σ (Fig.3) ana wakilta kwararar haɗin gwiwa ta zane-zane 1 na farko loading, 2 don taimako, 3 don nauyin na biyu har zuwa iyakar a na ƙarawa na farko σa da 4 wuce wannan iyaka.
Tsarin taimako2da zane-zane na matsawa na biyu3kafa madauki hysteresis a baya wanda zanen4ya ci gaba a cikin tsawo na zane1, ba tare da karaya ba, kamar babu saukewa da sakewa.
Sl.4. Tsarin canji na coefficient of porosity coefficient of undisturbed ground sample
Duk da haka, idan muka yi gwajin oedometer kamar yadda aka yi a baya tare da samfurin da ba shi da damuwa da aka ɗauka daga wani zurfin ƙasa (fig.4), zane don kaya na biyu3zai nuna a takamaiman kaya ɗaya σb karaya a batu b, bayan haka zane zai ci gaba.4suna da gangare mafi girma. Wannan karaya ya faru ne saboda ƙasar da aka ɗauko samfurin tana ƙarƙashin nauyi mafi girma p=γt fiye da nauyin samfurin σ a cikin oedometer. Babban kaya p ya samo asali ne daga nauyin shimfidar ƙasa na sama da ke wanzu zuwa saman ƙasa, wanda muke kira matsa lamba na ƙasa, ko kuma daga nauyin daɗaɗɗen ƙasa na farko da aka kwashe tsawon lokaci ta hanyar lalacewa ko daga ƙasa na moraine ko kankara, wanda muke kira preload. Bayyanar juzu’i na musamman na yumbu, inda muka bambanta tsakanin yumbu mai ƙarfi da ƙarfi.
Laka mai ƙarfi na yau da kullun
Ƙunƙarar yumɓu na yau da kullun yana cikin zurfin ƙasa da ƙasa, wanda a baya ba a fallasa shi don ɗaukar kaya. Samfurin wannan yumbu, wanda aka ɗora a cikin oedometer tare da nauyin nauyi fiye da nauyin saman “matsayin ƙasa” yadudduka, yana nuna ci gaba da gudana na ƙarfafawa, ba tare da karya ba a cikin zane-zane na matsawa na dangi ko a cikin zane-zane na porosity coefficient . Ƙaddamar da wannan yumbu a ƙarƙashin nauyin abu na al’ada ne, watau a ƙarƙashin wani nau’i, sulhu yana raguwa a tsawon lokaci.
Laka mai ƙarfi
Laka mai ƙarfi yana cikin zurfin zurfi ko kuma an riga an riga an yi masa lodi. Samfurin wannan yumbu da aka ɗora a cikin oedometer tare da matsa lamba mafi girma fiye da matsa lamba na ƙasa ko preload yana nuna karaya a kan zane na matsawa na dangi ko kuma akan zane-zane na porosity coefficient , abin da ake kira. geological fracture g, tare da canji mai ƙarfi a alkibla (fig.5a). Ƙaddamar da wannan yumbu a ƙarƙashin tsarin yana da ƙananan don nauyin da ke ƙasa da matsa lamba na ƙasa ko preload σ1, amma ya zama mafi girma ga lodi sama da σ1.
Idan ba a fayyace faɗuwar ƙasa a fili ba, to an ƙaddara ta amfani da tangents zuwa zane (Fig.5b).
Sl.5. _Tsarin canje-canje a cikin ƙididdiga na porosity na yumbu mai ƙarfi.
Tsare-tsare na lokaci
Ana samun wannan zane-zane, wanda kuma ake kira zane-zanen ƙarfafawa, lokacin da, kowane mataki na lodin samfurin a cikin oedometer, lokacin t a cikin sa’o’i ana amfani da shi zuwa ga abscissa axis, da daidaitawa a mm zuwa ga madaidaicin axis (Fig.6a) ko a cikin% na jimlar daidaitawa (Fig.6b).
Sl.6. Tsarin Zauren Lokaci
Ƙasar da ba a ɗaure da ɗaure ba tana da halaye daban-daban a ƙarƙashin kaya. Kasa mai kwance, kamar yashi, suna da manyan ramuka, wanda ruwa ke saurin matse shi a karkashin kaya, ta yadda kasa ta zauna cikin sauri, tare da mafi girman matsuguni da ke faruwa a farkon lodin kuma ya kai matakin karshe a wani kaya da aka bayar cikin kankanin lokaci. Ƙasar da aka haɗa kamar yumbu suna da ƙananan ramuka waɗanda ruwa ke da wuyar matsewa a ƙarƙashin kaya. Akwai matakai guda biyu a cikin tsarin lokaci na ƙaddamar da ƙasa. A cikin kashi na farko, nan da nan bayan yin amfani da kaya zuwa ƙasa, tun da ruwa ba zai iya gudana daga cikin pores ba, ya zama damuwa kuma ya karbi duk nauyin da aka yi amfani da shi. A mataki na biyu, ruwan famfo mai matsananciyar damuwa ya fara turawa a ƙarƙashin damuwa na kansa saboda nauyin nauyi, wanda a hankali ya canza shi zuwa ƙananan ƙwayoyin ƙasa. A cikin wannan kashi na biyu, ɓangarorin suna haɗuwa kuma ramukan suna raguwa. Tsarin raguwa yana ci gaba har sai an tilasta ruwa mai matsa lamba daga cikin pores, watau har sai yanayin damuwa na ruwa a cikin pores ya daina wanzuwa. Sabili da haka, ƙarfafa ƙasa shine da farko matsala ta hydrodynamic, wanda ya dogara da ƙarancin ƙasa da porosity. A cikin yanayin yumbu, wanda ƙarancinsa ya yi ƙasa, tsarin ƙarfafawa zai iya ɗaukar lokaci mai tsawo, kuma ƙari, ƙauyuka na iya zama mafi girma saboda girman porosity mafi girma fiye da yanayin yashi. Dangane da gwajin ƙarfafawa, ana iya ƙididdige kwas ɗin lokacin sasantawa na tsawon lokacin ƙarfafawa kuma a cikin kowane matakai.