Metro bolts feem ntau yog lined nplhaib-puab. Ib tug hneev ntsia liaj qhov rooj, ntawm qhov tod tes, yog ib qho precast hauv ob sab phlu ntawm pob zeb (uas feem ntau yog ua los ntawm ob peb daim). Nws yog tsuas yog siv nyob rau hauv kev tsim kho cov kav dej loj thiab subways. Nyob rau hauv tus txheej txheem ntawm qhov excavation, lub luag haujlwm tseem ceeb ntawm hneev ntsia hlau yog ua kom tsis muaj dej thiab txhawb nqa.
Chav kho yog hais txog cua sov lub pob zeb sab nraud kom nrawm tsim cov qauv sab hauv ntawm cov cement thiab cov tshuaj tiv thaiv hydration, yog li ntawd lub hardening tus nqi ntawm cov pob zeb yog ceev. Lub hom phiaj tseem ceeb yog kom luv lub voj voog hloov pauv ntawm cov qauv thiab ua kom cov zis ntau ntxiv. Raws li ib txwm muaj, txoj kev kho ntawm hneev ntsia hlau yog feem ntau atmospheric steam khoom, thiab plaub theem tseem ceeb ntawm kev saib xyuas yog: (1), pre-curing (Y); (2) Cua sov (s); (3) Txias (J) thiab qhov kub thiab txias (H)
Txoj kev sib txuas ntawm hneev ntsia hlau sab hauv lub nplhaib hauv ob sab phlu thiab cov ntsia hlau sab nraum lub nplhaib hauv ob sab phlu tuaj yeem muab faib ua ob hom: kev sib txuas yooj yooj yim thiab kev sib txuas tsis sib xws, nyob rau hauv ob qho tib si hneev ntsia hlau nyob rau hauv qhov kev sib txuas yooj yim tuaj yeem muaj kev sib hloov me ntsis thiab kev sib hloov, yog li ntawd. lub nplhaib hauv ob sab phlu tuaj yeem deformed raws li kev faib tawm ntawm lub zog sab hauv los hloov qhov kev ntxhov siab ntawm lub hauv ob sab phlu. Nyob rau hauv kev sib txuas nruj, tus naj npawb ntawm cov kab txuas ntawm cov bolts tuaj yeem nce ntxiv, thiab qhov rigidity ntawm txoj hauj lwm kev sib txuas yog tib yam li qhov rigidity ntawm hneev ntsia liaj qhov rooj nws tus kheej. Niaj hnub no, kev sib txuas yooj yim yog siv ntau dua.
Nyob rau hauv kev tsim kho ntawm subway tunnels, peb feem ntau siv subway bolts rau kev tsim kho. Lub hauv ob sab phlu yog cylindrical, txuas nrog hneev ntsia hlau hauv cov pob zeb muaj zog. Daim ntawv tsim no yuav tsum tau grouted ntawm qhov chaw tshwj xeeb ntawm cov ntsia hlau txuas thiab cov ntsia hlau subway, thiab lub luag haujlwm tseem ceeb yog tiv thaiv kev nkag mus thiab tsis muaj dej.