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’ajin fasaha kuma ba tayin ƙirar geotechnical ba, gwajin dakin gwaje-gwaje ko aikin ƙasa.
Matakan kayan a cikin ƙasa
Ƙasa ta ƙunshi matakai uku: m, ruwa da gas. Tsayayyen lokaci yana wakilta da ƙaƙƙarfan barbashi, ruwa mai ruwa, da lokacin iskar gas ta rufaffiyar iska ko tururin ruwa a cikin pores na ƙasa. Wasu nau’ikan ƙasa na iya ƙunshi nau’i ɗaya, biyu ko uku, wanda ke nufin ƙasa tana iya zama tsarin lokaci ɗaya ko biyu ko uku. Kaddarorin jiki na ƙasa sun dogara da matakan mutum ɗaya. Ƙasar da ba ta da daidaituwa, kamar yashi ko tsakuwa gaba ɗaya, ta ƙunshi lokaci ɗaya kawai - ƙwararrun ƙwayoyin cuta. Iskar da ke cikin ramukan wannan ƙasa ba a rufe take kuma baya adawa da motsin ƙaƙƙarfan ɓangarorin, don haka ba za a iya la’akari da wani lokaci ba. Danshi mai daidaituwar ƙasa sama da matakin ruwa na ƙasa, wanda ya ƙunshi ƙaƙƙarfan barbashi da rufaffiyar pores, cike da ruwa da wani sashi da iska ko tururin ruwa, ƙasa ce ta tsarin matakai uku. A cikin yanayin motsi mai ƙarfi, ruwa da iska a cikin pores na ƙasa suna adawa a lokaci guda. Ƙasar da ke ƙasa da matakin ruwan ƙasa, wanda kofofinta suka cika da ruwa gaba ɗaya, ta yadda babu iska ko tururin ruwa a cikin su, tsari ne mai nau’i biyu. Ƙasar da ke cikin zurfin yadudduka ana zaton ta kasance na tsarin tsari guda biyu, saboda rufaffiyar iska a cikin pores na ƙasa a zurfin zurfi ba shi da wani tasiri mai mahimmanci a kan abubuwan da ke cikin jiki, wanda a cikin wannan yanayin an ƙaddara ta hanyar kaddarorin masu ƙarfi da ruwa.
Granulometric abun da ke ciki
Tushen ƙasa ma’adinai ne ko kwayoyin halitta masu girma dabam dabam, kama daga manyan tsakuwa da tubalan, ɗaruruwan ɗaruruwa da dubban millimeters a girman, zuwa girman ƙwayar ƙwayar cuta guda ɗaya. Kamar yadda ka sani, kwayoyin halitta shine miliyan daya na millimita, millimicron daya. Ana ɗaukar ƙaramin ƙaƙƙarfan ƙaƙƙarfan ƙasa zuwa sama20 mko microns. Ƙaƙƙarfan ƙaƙƙarfan barbashi na ƙasa yana da tasiri mai girma akan kaddarorinsa na zahiri. Wannan ƙaƙƙarfan yana bayyana ta hanyar abun da ke ciki na granulometric, wanda ke wakiltar rabon girman nau’in hatsi na kowane nau’in nau’in nauyin nauyin su zuwa jimlar nauyin ƙasa. Rarraba ƙasa bisa ga tsarin granulometric ya bambanta a cikin ƙasashe daban-daban. Rabon mu shine kamar haka:
Iyakar girman barbashi
Girman2 mm- iyakar da ke tsakanin ƙaƙƙarfan hatsi da ƙasa mai laushi. Tsayayyen barbashi na har zuwa2mmnuna hawan jini na ruwa a cikin ƙasa. Ƙasar ƙaƙƙarfan hatsi ba ta da ƙarfin ƙarfi. Girman0,2 mm- iyaka tsakanin ƙaƙƙarfan hatsi (kaifi) da yashi mai laushi (mai laushi). Girman0,02 mm- iyakar da za a iya gane nau’in hatsi a cikin ƙasa da ido tsirara. Girman0,002 mm– iyaka tsakanin sako-sako da ƙasa da yumbu Girman0,0002 mm– iyaka tsakanin yumbu da colloidal lãka. M sinadaran girma a kasa0,002 mmsuna da babban tasiri a kan kaddarorin jiki na ƙasa. Wadannan sinadarai suna ba da haɗin gwiwar ƙasa, kuma idan sun kasance ƙanana kuma sun fi yawa a cikin ƙasa, haɗin ƙasa ya fi bayyana. Duk da haka, da cohesiveness na ƙasa kuma ya dogara da ma’adinai abun da ke ciki na m barbashi karami fiye da0,002 mm. Idan wadannan barbashi sun samo asali ne ta hanyar rugujewar ma’adanai masu tauri irin su quartz, to haduwar su ba ta da yawa ko kuma babu shi, kuma shayarwarsu ta yi kadan. Idan barbashi suna ƙasa0,002 mmsamu ta hanyar bazuwar kayan yumbu, to, suna da kaddarorin ɗaure waɗanda duk sun fi ƙarfi idan ɓangarorin sun fi ƙanƙanta, yayin da shayarwar ruwa na irin waɗannan abubuwan yana da girma sosai. Tsarin granulometric na ƙasa yana ba da bayanai masu mahimmanci kuma abin dogara akan wasu abubuwan da ke cikin jiki. Idan ƙasa ta mamaye barbashi na yumbu mai girman ƙasa0,002 mm, to, riga ya dogara da cewa za’a iya ƙaddamar da cewa irin wannan ƙasa shine filastik, mai daidaitawa, hygroscopic, yana da babban capillarity, low permeability kuma yana da ƙananan kusurwa na rikici na ciki. Tsarin granulometric na ƙasa yana wakilta ta layukan granulometric abun da ke ciki (Fig.1).
Layin Granulometric don yashi tsakuwa, yashi mai ƙura, ƙurar yashi, ƙasa mai yumbu da yumbu
Sl.1- Lines na granulometric ƙasa abun da ke ciki:1- yashi mai kauri;2- yashi mai ƙura;3- ƙurar yashi;4- ƙasa yumbu;5- yumbu
Matsakaicin layukan abun da ke ciki na granulometric suna nuna juzu’i mai ƙarfi na ƙaƙƙarfan barbashi ƙanana fiye da diamita da ke wakilta ta abscissa na wurin da aka bayar. Misali, a point A na layi4hukumar ta nuna cewa akwai92%girman barbashi kasa da2 mm, da kuma cewa su ne sauran8%girman girman2 mm.
Rarraba ƙasa bisa ga abun da ke ciki na granulometric
Ƙasa mai ɗauke da daskararren barbashi sama2 mmAn rarraba bisa ga babban rabo na ƙasa ta hanyar granulometric abun da ke ciki, wanda aka nuna a cikin fig.1. A yin haka, wanda aka fi wakilta a cikin ƙasa ana ɗaukar shi azaman juzu’i na asali, yayin da sauran ƙari. Misali, idan babban granulation na ƙasa galibi yashi ne tare da ɗan ƙaramin tsakuwa, to ana rarraba irin wannan ƙasa a matsayin yashi mai ƙaƙƙarfa, yayin da akasin haka zai zama tsakuwa mai yashi. A cikin rarrabuwa, ana iya nuna hannun jari na kowane juzu’i a cikin ƙasa. Idan, alal misali, ƙasa ta ƙunshi15%yumbu,45%kura,30%yashi da10%tsakuwa, ana iya rarraba shi azaman ƙasa yumbu da15%yumbu da10%tsakuwa. Duk da haka, ga ƙasa mai laushi mai laushi wanda ke dauke da m barbashi kasa da2 mm, rarrabuwa bisa ga tsarin su na granulometric yawanci ana yin su bisa ga zane-zanen triangular. Akwai irin waɗannan zane-zane da yawa, waɗanda za mu lissafa mafi mahimmanci daga Ofishin Ƙasa na Amurka, fig.2.
Triangular zane na rarrabuwar ƙasa bisa ga yawan yashi, ƙura da yumbu
Sl.2- Hoton U.S. Soil Bureau
Jadawalin ya ƙunshi gatura masu daidaitawa guda uku waɗanda aka jera a cikin madaidaicin alwatika, a cikinsa kowanne axis yana wakiltar juzu’i ɗaya, wato yashi, ƙura da yumbu a cikin % bisa nauyin nauyin ƙasa duka. An raba yankin zanen zuwa10zone, kowannensu yana wakiltar wani nau’in ƙasa daban. Kowane gefen triangle yana wakiltar abscissa wanda daga ciki aka ɗaga daidaitawa daidai da sauran abscissas guda biyu. Kowane batu a cikin wannan zane yana da3daidaitawa masu wakiltar kaso da aka jera3ɓangarorin a cikin ƙasa da aka bayar kuma ƙayyade nau’in ƙasa. Don haka, alal misali, maki M akan zane yana wakiltar yumbu. An samo shi ta hanyar daga zane na granulometric abun da ke ciki fig.1Ƙayyade ƙungiyoyi ɗaya, waɗanda a cikin wannan yanayin zai kasance (layi4a cikin fig.1):35%yumbu,25%kura,40%yashi, inda adadin8%tsakuwa sakaci tunda yakai kasa10%. Wannan rabe-rabe yana nufin ɓangarorin yashi, ƙura da tsakuwa bisa ga sashin Amurka, amma an karbe shi a haka saboda ƙimar kwatancen da ƙwarewar da yake da ita tare da irin wannan rarrabuwa.
Digiri na rashin daidaituwar ƙasa
A cewar Allen Hazen, matakin rashin daidaituwar ƙasa shine rabo (fig.3)
U=d60/d10
ku d60hatsi diamita daidai da ordinate60%, da d10 Diamita na hatsi daidai da ordinate10%.
Na U< 5 tlo je ravnomernog sastava,
don U =5-15ƙasa ba daidai ba ce a cikin abun da ke ciki.
don U>15Ƙasar ba ta da daidaituwa.
Lokacin da layin granulometric abun da ke ciki ya kasance m, darajar matakin rashin daidaituwa U ƙananan ne, yayin da layin layi yana da girma. Mafi ƙarancin ƙima na U shine1. Idan layin granulometric abun da ke ciki ya fi lebur, ƙimar U ya fi girma. Don yashi yawanci U=1-15, don ƙasan yumbu U=10-90, amma a yanayin ƙasa mai ƙanƙan da ba daidai ba, U na iya samun manyan ƙima.
Sl.3- Tabbatar da diamita na hatsi d60kuma d10
Tace dokar
Wannan doka ta dogara ne akan nau’in granulometric na tacewa, aikin wanda shine don rage girman hydraulic a lamba tsakanin ƙasa da dutsen magudanar ruwa ta hanyar girman hatsi na tsaka-tsakin, don hana wanke ƙananan ƙwayoyin ƙasa ta hanyar ruwa. Sharuɗɗa na asali waɗanda ya kamata madaidaicin tacewa ya dace su ne cewa ya zama mai jujjuya ruwa da kwanciyar hankali. Akwai dokoki da yawa don abun da ke ciki na masu tacewa, daga cikinsu akwai kawai tsarin Terzaghi a nan a matsayin mafi sanannun.
Mulkin Terzaghi
Dokar Terzaghi ta karanta: granulation na tace ya kamata ya zama irin wannan hatsi a adadi.15%sassa ta nauyi na gabaɗayan yawan tacewa (F15) zama mafi ƙanƙanta4sau girma fiye da mafi ƙasƙanci barbashi a kan abin da tace rests (kwassai) a adadin15%na sassa da nauyin tushe (B15), ba tare da ya fi girma ba4lokaci B85, wannan shine girman mafi ƙanƙanta barbashi a85%sassa da nauyin tushe. Ana iya bayyana wannan doka ta hanyar alaƙa:
F15/B15>4kuma F15/B85< 4.
Rabo na farko yana tabbatar da ƙarancin ruwa na tacewa, yayin da na biyu ya tabbatar da kwanciyar hankali.
Sl.4- Tsarin tacewa na Terzaghia
Ana gabatar da mafi ƙanƙanta da mafi girma na tushe a cikin fig.4layukan iyaka1kuma2. Layukan iyaka na tace sune3kuma4. Halin F15>4_B15_ ana wakilta ta da aya a kan layin iyaka3, Sharadi F15< 4_B85_ tačkom b na liniji 4.
Ana ba da shawarar cewa layin granulometric abun da ke ciki na tace ya zama kusan daidai da layin granulometric abun da ke cikin tushe.
A maimakon biyu matsananci Lines na granulometric abun da ke ciki na tushe kamar yadda a cikin fig.4, zai iya zama layi ɗaya na matsakaicin hatsi. A wannan yanayin, maki B15 da B85 suna kan layi daya (kamar yadda yake cikin fig.5).
Mafi sau da yawa, bambanci a cikin granulation tsakanin tushe da magudanar ruwa shine irin wannan yanki guda ɗaya bai isa ba don sauyawa tsakanin tushe da Layer. A wannan yanayin, tacewa ta ƙunshi yankuna da yawa masu tacewa, waɗanda aka ƙaddara bisa ga ka’ida ɗaya, har sai an kai girman girman hatsi na ajiyar magudanar ruwa.
Sl.5- Misalin lissafin matakan tacewa
Rarraba da ke sama, ƙayyadaddun ƙayyadaddun ƙa’idodi da ƙa’idodi ana canja su daga tushen tarihi kuma ba su zama madadin rarrabuwar kayyakin ƙasa na yanzu ba, rahoton dakin gwaje-gwaje, ƙirar tacewa ko shirin aiki. Ainihin tsarin ƙasa da magudanar ruwa yana buƙatar samfurin wakilci, gwajin da ya dace, bincikar ruwa na ƙasa da ƙasa, yashwa da kwanciyar hankali na ciki, da kuma kimantawa ta ƙwararren masani bisa ga ƙa’idodi da yanayin takamaiman aikin.