| 摘要 |
This invention belongs to the pit digging technology field and relates to reusable telescopic metal risers (1) used for pit digging and later, when required construction or repair work in the pit has been completed, for full or partial filling of the pit. In digging a deep pit in confined space where other objects are 1-1.5 metre away from the edge of the pit telescopic-type retractable round metal risers (1) of different diameters are used to ensure stability of walls of the pit being dug and safely achieve the desired depth of the pit, enable doing the required repair or construction work;this work having been done the risers are pulled out from the pit one after another and the pit gets gradually completely or partially filled as the telescopic-type risers are pulled out back to the surface one after another. |
