Manhole pwm feem ntau yog ua los ntawm ob yam khoom tseem ceeb: yas thiab hlau. Cov khoom sib txawv muaj cov yam ntxwv sib txawv, cov xwm txheej siv tau, thiab cov txheej txheem ua. Qhov tseem ceeb yog xaiv hom tsim nyog raws li lub manhole qhov chaw siv, kev tsim kho, thiab cov nqi siv nyiaj. Ntawm cov ntaub ntawv yas, siab - ntom polyethylene (HDPE) yog qhov kev xaiv loj. Cov khoom siv no muaj cov tshuaj lom neeg ruaj khov, tiv taus cov kua qaub thiab alkali corrosion, thiab tuaj yeem hloov mus rau cov xwm txheej uas muaj corrosive media xws li cov kav dej hauv nroog thiab cov kav dej hauv zej zog. Nws kuj yog lub teeb yuag (ntau dua 50% sib dua li cov pwm steel ntawm tib qhov loj), ua kom yooj yim rau kev tswj thiab sib dhos. Moulded manhole nto yog du thiab tsis yooj yim stained. Txawm li cas los xij, cov khoom siv HDPE muaj qhov tsis muaj cua sov ua haujlwm thiab rigidity. Thaum raug kub siab (xws li lub caij ntuj sov raug tshav ntuj) los yog raug rau sab nraud siab (xws li cov chaw crushed los ntawm cov tsheb hnyav), nws yog feem ntau deformation me ntsis. Yog li ntawd, nws yog feem ntau haum rau manhole scenarios zoo tib yam uas tsis yog - hnyav loads. Polypropylene (PP) kuj yog cov khoom siv rau cov pwm yas. Nws cov rigidity yog me ntsis zoo dua HDPE, thiab nws qhov kub thiab txias yog dav dua (-20℃txog 120 degree), tab sis nws qhov kub tsis kam yog me ntsis phem dua. Thaum siv rau hauv cov cheeb tsam txias, cov tshuaj tua kab mob yuav tsum tau ntxiv rau kev hloov kho. Nws feem ntau yog siv rau me me manhole pwm nyob rau hauv temperate climates.
Ntawm cov ntaub ntawv hlau, carbon structural steel (xws li Q235 thiab Q355) yog hom siv dav tshaj plaws. Hom hlau no muaj lub zog siab thiab nruj, tuaj yeem tiv taus cov khoom hnyav thiab siv ntau zaus, thiab tsim nyog rau kev siv manhole hauv txoj kev loj hauv nroog, chaw tsim khoom, thiab lwm yam xwm txheej uas nws yuav tsum tau tiv taus ntev - lub sijhawm tsheb tsheb lossis kev cuam tshuam sab nraud. Cov pwm hlau tuaj yeem raug welded thiab khoov rau hauv cov txheej txheem nyuaj (xws li cov manholes irregularly zoo li tus manholes thiab loj-size manholes) thiab muaj lub neej ntev kev pab cuam (tuaj yeem rov qab siv ntau dua 50 zaug hauv kev saib xyuas ib txwm). Txawm li cas los xij, cov pwm steel yog hnyav (4-meter- ntev pwm tuaj yeem hnyav tshaj 300kg), yuav tsum tau siv cov cuab yeej siv, thiab nws yooj yim rau xeb, yuav tsum tau tshem tawm xeb thiab tiv thaiv kev kho mob (xws li tshuaj tsuag epoxy zinc-nplua nuj xim). Stainless hlau (xws li 304 thiab 316) manhole pwm yog tsim rau cov xwm txheej tshwj xeeb uas muaj zog corrosion (xws li tshuaj lom neeg chaw ua si thiab chaw ntug dej hiav txwv). Lawv cov kev tiv thaiv corrosion yog qhov zoo tshaj plaws ntawm cov pa roj carbon zoo tib yam, thiab lawv qhov chaw muaj qhov siab ntawm smoothness, ua rau nws nyuaj rau cov av ua raws. Txawm li cas los xij, lawv kim dua (3-5 npaug ntawm cov pwm hlau zoo tib yam) thiab feem ntau tsuas yog siv nyob rau hauv qhov chaw tshwj xeeb uas muaj corrosion thiab siab.
Tsis tas li ntawd, muaj qee qhov sib xyaw manhole pwm, xws li fiberglass reinforced yas (FRP). Cov khoom siv no sib txuas cov kev tiv thaiv corrosion ntawm cov yas nrog lub zog siab ntawm cov hlau. Nws yog sib dua li cov pwm steel thiab ruaj khov dua li cov pwm yas, tab sis nws txoj kev ua haujlwm yog qhov nyuaj thiab nws cov nqi kuj yog siab, txwv tsis pub nws daim ntawv thov. Nws feem ntau yog siv rau hauv cov xwm txheej tshwj xeeb engineering uas yuav tsum muaj qhov hnyav, lub zog, thiab kev tiv thaiv corrosion. Zuag qhia tag nrho, cov ntaub ntawv sib txawv rau manhole pwm muaj lawv tus kheej tsim nyog daim ntawv thov, thiab kev xaiv yuav tsum tau ua raws li kev xav tau ntawm qhov kev siv tiag tiag, qhov yuav tsum tau ua, thiab tus nqi.