Sib txawv ntawm cov khoom
Nws tuaj yeem muab faib ua 4 pawg
A. Hlau manhole npog: cam khwb cia hlau, ductile hlau, bronze manhole npog, thiab lwm yam;
B. Lub zog muaj zog steel fiber ntau cement qhob manhole npog (cov khoom siv cement-based composite);
C. Regenerated resin zoo npog (regenerated resin matrix composite);
D. Polymer matrix composite soj ntsuam zoo npog, thiab lwm yam.
Paub qhov txawv ntawm cov duab
Square manhole npog
Nws feem ntau muab faib ua lub voj voog thiab square.
Nyob rau hauv cov nqe lus ntawm txoj kev tswj hwm hauv nroog, cov npog npog zoo feem ntau siv vim lawv tsis yooj yim rau qaij, uas tuaj yeem tiv thaiv kev nyab xeeb ntawm cov neeg taug kev thiab tsheb zoo dua.
Nyob rau hauv cov cheeb tsam nyob deb nroog thiab cable qhov dej, square feem ntau yog siv los tiv thaiv cov dej nag thiab lwm yam dej nkag.