A wide range of alternatives is available to design a support system to stabilize an underground opening under squeezing conditions. An underground mine development was selected for the research where the underground openings reach to a depth of 1000 m and weak geological formations are present. The operational concerns in the mine development led to a shaft support design having a thick reinforced concrete with very high early strength while the decline was supported by a traditional support system in the squeezing ground. The rigid support in the shaft was typically capable of sustaining high ground pressure and stabilized the opening within negligible radial displacements. It should be noted that the design of the rigid system was straightforward and high early strength concrete had key importance in this case, however, it could only be applied in the shaft. The traditional support system for the decline was a light and conventional system, consisting of thin shotcrete layer, cable bolts and steel arches suffered excessive deformation as high as 60 cm or more. A light-flexible support system with a radial gap was developed for the decline in the same geological unit, allowed substantial ground deformation to occur in a controlled manner, eventually, the opening was stabilized. The newly adopted radial gap allowed improved ground relaxation and reduction of the ground pressure acting on the secondary support layer. The design and application of the yielding support system with a radial deformation gap was effortful, hence the system can be used where available equipment and operational factors force practitioner to use a light and flexible system. The significance of the new system arises from keeping the ground support elements and the operation cycle the same while modifying the support design and installation procedure.

中文翻译：

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煤矿开发中挤压岩石条件下带径向间隙柔性支撑系统的现场评估

各种各样的替代方案可用于设计支撑系统，以在挤压条件下稳定地下开口。选择了一个地下矿山开发进行研究，其中地下洞口达到1000 m的深度并且存在薄弱的地质构造。矿山开发中的运营问题导致竖井支护设计采用了具有很高早期强度的厚钢筋混凝土，而下降的原因是在挤压地面上使用了传统的支护系统。轴中的刚性支撑通常能够承受较高的地面压力，并将开口稳定在可忽略的径向位移范围内。应当指出的是，刚性系统的设计非常简单，在这种情况下，高强度的早期混凝土至关重要。它只能应用于轴中。下降的传统支撑系统是轻型的常规系统，由薄喷浆层，电缆螺栓和钢拱组成，变形高达60厘米或以上。针对同一地质单元的下降，开发了具有径向间隙的光柔性支撑系统，允许以受控的方式发生较大的地面变形，最终使开口稳定。新采用的径向间隙可以改善地面松弛程度，并降低作用在辅助支撑层上的地面压力。具有径向变形间隙的屈服支撑系统的设计和应用非常费力，因此可以在可用的设备和操作因素迫使从业人员使用轻便而灵活的系统的情况下使用该系统。