层状岩体地下洞室施工阶段围岩精细化分级

Study on Fine Classification of Surrounding Rock During Construction Stage of Underground Cavern with Layered Rock Mass

围岩分级方法在实际应用中存在结果处理复杂、围岩分级量化数值范围交叉及围岩分级精度较低等问题,为了对层状岩体地下洞室施工阶段的围岩进行精细化分级,基于HC分类法,重点考虑层状岩体的层厚与产状对围岩稳定的影响,通过有限元软件Midas GTS对25种由正交试验方法得到的代表性工况进行了数值模拟,并将位移计算结果进行了极差分析。结果表明:层状岩体隧洞位移分布方向主要取决于结构面走向与洞轴线夹角α及结构面倾角β,而位移分布范围的大小主要取决于岩层厚度h;对层状岩体隧洞稳定性影响的大小排序为,饱和单轴抗压强度R_(c)>结构面走向与洞轴线夹角α>张开度W>层状岩体层厚h>结构面倾角β,因此,层状岩体隧洞围岩分级时,应充分考虑结构面产状的影响;饱和单轴抗压强度R_(c)、结构面走向与洞轴线夹角α均与层状岩体隧洞的稳定性近似呈正比,张开度W则与层状岩体隧洞的稳定性近似呈反比;层状岩体层厚h=0.6 m时,层状岩体隧洞稳定性最差,结构面倾角β=60°时,层状岩体隧洞稳定最差。基于HC分类法提出了基于隧道相对变形的修正分级区间,并分别采用了模糊物元理论以及相似工程中的推广应用对其进行验证,证明了该分级区间的合理性及适用性。该分级区间可为类似地下洞室的围岩分级提供参考。

In order to finely classify the surrounding rock in the construction stage of the underground cavern of layered rock mass,at the same time,in view of the problems of the current surrounding rock classification methods in practical application,such as complicated result processing,overlapping numerical ranges of surrounding rock classification quantification and low accuracy of surrounding rock classification.Based on the HC classification method,this paper focuses on the influence of layer thickness and occurrence of layered rock mass on the stability of surrounding rock.The numerical simulation of 25representative cases obtained by the orthogonal test method is carried out by the finite element software Midas GTS.And the range analysis of the displacement calculation results is carried out.The results show that:the displacement distribution direction of layered rock tunnel mainly depends on the angleαbetween the strike of structural plane and the axis of the tunnel and the inclination angleβof structural plane,while the displacement distribution range mainly depends on the thickness h of rock stratum;The order of the influence on the stability of the layereduc2A rock tunnel is:saturated uniaxial compressive strength R_(c)>the angle between the structural plane strike and the tunnel axisα>the opening degree W>the layer thickness h>the structural plane inclinationβ,therefore,when grading the surrounding rock of a layered rock mass tunnel,the influence of the occurrence of the structural plane should be fully considered;The saturated uniaxial compressive strength R_(c),the angleαbetween the structural plane and the tunnel axis are all approximately proportional to the stability of the layered rock tunnel,the opening degree W is approximately inversely proportional to the stability of the layered rock tunnel;When the layer thickness of the layered rock mass is h=0.6m,the stability of the layered rock mass tunnel is the worst,and when the structural plane inclination angleβ=60°,the stability of the layered rock mass tunnel is the worst;Finally,based on the HC classification method,the modified classification interval based on the relative deformation of the tunnel is proposed,and the rationality and applicability of the classification interval are proved by the fuzzy matter-element theory and its application in similar projects.It is concluded that this classification interval can provide a reference for the classification of surrounding rocks of similar underground caverns.