凿岩台车采用长短眼配套控制隧道超挖技术

为有效降低施工成本，减小钻爆法隧道超挖量，提高钻爆施工技术及改进施工工艺，通过研究凿岩台车作业模式，分析得出凿岩台车进行隧道钻爆开挖时，由于受台车钻臂结构影响以及现场视线不清、视距较远等，钻凿周边眼时外插角不易控制，产生的隧道超挖往往较大。结合工程实践，通过对比凿岩台车在初期支护紧跟掌子面及不紧跟掌子面等不同施工工况下长短孔配套施工产生的超挖量，得出在保证施工安全的前提下，保留一定长度的隧道不进行初期支护施工钻孔，并采用长短孔配套钻孔爆破技术，可有效控制凿岩台车钻爆时隧道的超挖量。研究结果表明： 采用长短孔配套钻孔时，Ⅱ、Ⅲ级围岩，Ⅳ级围岩，Ⅴ级围岩相比类似条件只采用长眼时的最大超挖量分别减少约12、19.5、21.5 cm。

Tunnel Overbreak Control Technology by Rockdrilling Jumbowith Long and Short Blasting Holes

In order to effectively reduce the construction cost and the overbreak amount by drilling and blasting method, and improve the drilling and blasting construction technology, the operation mode of the rock drilling jumbo is studied, and it is concluded that when the rock drilling jumbo is used for tunnel drilling and blasting excavation, the external angle when drilling the peripheral blasting holes is difficult to be controlled, and the tunnel overbreak amount is always large due to the influence of the boom structure of jumbo, unclear field sight and relatively long visual distance. Furthermore, comparison and contrast is made on the overbreak amounts induced by matching construction of long and short blasting holes under different construction conditions, such as primary support closely following tunnel face and that not following tunnel face. It is concluded that under the premise of ensuring construction safety, the method that retaining a certain length of tunnel without construction drilling for primary support and using matching drilling and blasting technology of long and short blasting holes can effectively control the amount of tunnel overbreak during drilling and blasting by using rock drilling jumbo. The results show that the maximum overbreak amounts of Grade Ⅱ and Ⅲ, Grade Ⅳ and Grade Ⅴ surrounding rocks when using long and short blasting holes are 12 cm, 19.5 cm and 21.5 cm less than that when using long blasting hole, respectively.