I-Small Diameter DTH Drilling in Foundation

Ukumba Okuncane Kwedonga (DTH) yindidi ethile yokumba ngemishini yokuphakamisa esetshenziselwa ukwakhiwa kwezimpande ezijulile ngenxa yokufaka nokulungiselela izinhlelo zokuzinzisa umhlaba, izindwangu zokuphuca, nezingxenye zokwakha ngaphakathi kwendawo yamaDwala Omhlaba neZindwangu Zokuphuca. Le teknoloji ibalulekile kakhulu ngenxa yokunemba kwayo, ukujula, nokuphumelela kwezindleko lapho kucwaningwa ama-boreholes aphakathi kuka-50 no-150 milimitha ububanzi, kwenza kube ithuluzi elibalulekile ekwakheni izimpande zanamuhla ezindaweni zedolobha nezindawo zemvelo ezinzima. Izicelo eziyinhloko zokumba okuncane kwe-DTH zihlanganisa izixazululo eziningi zokwakha izimpande. Ekukhiqizeni izindwangu zokuphuca, ukumboza kwe-DTH kudala ama-boreholes okuqeqesha ezokusebenza kwe-grouting, kusungula izithiyo eziyizingxenye ezilungile ezilawula uku leaking phansi kwemibhoshongo, ama-dikes, kanye nezindawo zokucwila. Le teknoloji ibalulekile futhi ezinhlelweni zokuhlanganisa umhlabathi, lapho ama-boreholes asondele edalayeni angakhulisa amandla omhlaba futhi yehlise ukuhamba okuhlukahlukene. Ekukhiqizeni ama-piles amaphuzu, ukumba kwe-DTH kukhipha kahle ama-boreholes ahlangene akha ubukhulu bendawo ngaphandle kokuphazamiseka komhlaba. Ngaphezu kwalokho, le teknoloji isekela imisebenzi ye-jet grouting ngokusungula ama-pilot holes aphumile ngendlela efanele aholela kumagempu aphezulu, futhi ifaka isandla ekwakhiweni kwezindonga zokuhamba kwezindonga ngokulawula ukumba ezimeni zomhlabathi ezahlukene. Ukumba kwe-DTH kusebenzelana nomgomo wokuqhuma kwemiphunga okuhlanganiswa nokuphothulwa kwemashini. I-hammer esebenzisa umoya ibhampa i-drill bit efakwe ezansi kwalokho, ikhiqiza ukuphindaphinda kokuhlasela okuphula itshalo nomhlaba, kanti ukuhamba kancane kwe-bit kususa impahla eyaphukile. Umoya ophephile uhlehla khona ngesikhathi esifanayo uveza okuphukile phezulu ngobumnene phakathi komufudlana namadwala e-borehole, kugcina ukusebenza kokumba futhi kuvumela ukuhlolwa kwezindawo ze-geological ngesikhathi sangempela. Le msebenzi ye-mekhkaniki ibalulekile kakhulu ezimweni zokubhekelela ezihlanganisa isihlabathi, izi-gabbro, ama-cobbles, kanye nemihlaba ethambile evamile kumazinga okwakha. Izinguquko zezisetshenziswa kule ndidi ziqala ezinhlelweni ezithwalayo zokumba ezinamakhomprasi asetshenziswayo (ngokuvamile 500–800 CFM ku-100+ psi) kuya ezinhlelweni ezisekelwa ezinjengaleso esikwi-skid ezikhona ezindaweni ezinamakhungathekile. Usayizi wamashunu we-DTH ukhethwa ngokuhambelana nezidingo zokubanzi nezimo zomdabu; amashunu amancane (2–3 intshi) akhiqiza ama-boreholes angu-50–75mm, kuyilapho amashunu aphakathi (3–4 intshi) akumba ama-diameters angu-100–150mm. Ama-rotary head assemblies anikeza ukujula okuqondile, kuhlangene nokuhlanganyela kwencudla yokuphumula ukuze kwandiswe izinga lokungena kwezimiso ezahlukene zomhlaba nezinhlekelele. Izinkomba zokukhetha izikhungo zikhanga ukuhamba kwedijithali kwezinguquko ezihlanganisa izindawo, ukumelana nezikhala zembobo (ngokuvamile ±1–2% yokuphakamisa), izidingo zomoya uma kuqhathaniswa namakhomprasi, kanye nokuzivumelanisa nezimo eziguquguqukayo zomhlaba. Ochwepheshe bahlola umsebenzi we-hammer ngokumelene nokuhlola ubukhulu, ubuqotho bokuxhumana kwethusi ngaphansi kokuphazamiseka, kanye nemfundo yokuthola yokuthola ukuqedela ama-borehole. Amandla okumba ukuphuma, kuncike ezikhathini zokusebenza ngaphambi kokunakekelwa, kanye nokuhambisana nezakhiwo zokukhakha noma zokuzinzisa kuholela ezinqumweni zokuthenga. Amaphuzu ahlobene ahlanganisa i-ISO 6753 (imigomo yokumba kwe-percussion), i-ISO 11760 (izinhlelo zokumba izinto ezishayayo ezilungiselelwe izicelo ze-DTH), kanye nezindlela ezahlukahlukene zendawo (i-DIN 18320, EN 14679) ezichaza izimiso zokwakha izindwangu zokuphuca nezokuzinzisa umhlaba ezihlanganisa izinqubo zokumba kwe-DTH. Abaphathi kufanele baqinisekise ukuhambelana kwezisetshenziswa nemikhawulo yokwakha nezikhala (EN 12639) kanye nezilinganiso zengcindezi yokusebenza efanele ezisebenzayo(EN 13786).