我矿采用淹水沉井法施工突破表土层。在沉井阶段,主副井筒均是变径的,其形状象一只倒竖的大烟囱。这样的井筒有如下优点:①由于井壁上薄下厚,可以节约一部分水泥。②由于井筒上轻下重,增加了井筒的稳定性,即使井筒有微小倾斜,也不影响井筒的有效利用面积。在浇灌井壁时,我矿采用自己设计制造的变径金属活动模板,这种模板可以任意调节 I mine flooding caisson construction breakthrough topsoil. In the caisson stage, both primary and secondary wellbores are tapered and shaped like an inverted vertical chimney. Such wellbores have the following advantages: ① Because the thin wall thickness, you can save part of the cement. ② Because the light weight on the wellbore increases the stability of the wellbore, even if the wellbore is slightly inclined, it does not affect the effective utilization area of ​​the wellbore. When watering the wellbore, I use mine own design and manufacture of adjustable metal activity template, this template can be adjusted