隧道围岩变形的尺寸效应研究

通过分析不同结构围岩的变形机制研究隧道变形的尺寸效应，研究结果表明隧道围岩变形的尺寸效应与围岩的变形机制存在密切的关系。围岩中由于结构面的存在使围岩的变形机制复杂多样，主要包括材料变形和结构变形两大类，围岩变形的尺寸效应也主要体现在材料变形和结构变形两方面。围岩材料变形包括弹性变形和塑性变形，均与围岩断面尺寸呈线性比例关系；围岩结构变形的尺寸效应表现为：（1）围岩结构类型随隧道断面尺寸的增大而发生改变，不同类型的围岩其变形机制不同，不同变形机制产生的围岩变形量相差较大；（2）在同一种围岩结构下，相同变形机制产生的围岩变形量也会随着隧道尺寸增大而呈现不同的变化规律，如在块状围岩中，隧道周边不可动块体会随着隧道断面尺寸的增大而转化成可动块体，从而发生滑动或者滚动变形，甚至坍塌；在层状围岩中，岩层的弯曲变形与隧道断面尺寸的平方成正比。

Study of size effect of deformation of rockmass surrounding tunnel

Size effect of tunnel deformation has been studied in this paper based on the deformation mechanism of different structures of rock mass. Size effect on deformation of rock mass surrounding tunnels closely relates to deformation mechanism of rock mass. Deformation mechanism of surrounding rock, which is intricate and diverse because of structural planes in the rock, includes material deformation and structural deformation. Size effect of deformation also reflects in the material deformation and structural deformation. Material deformation of surrounding rock varies directly as cross-section dimension of tunnels. Size effect of structural deformation is much more intricate. On the one hand, cross-section dimension of tunnels affects structure type of surrounding rock which closely relates to deformation mechanism; while amount of deformation provoked by different deformation mechanisms varies a great deal. On the other hand, in a same surrounding rock, amount of deformation provoked by an identical deformation mechanism also varies with size of tunnels. In the massive surrounding rock, for example, immobile rock surrounding tunnels will convert into movable rock in company with increase of cross section dimension of tunnels, and sliding or rolling deformation occurs sequentially. In the layered surrounding rock, bending deformation of rock stratification varies directly as the square of cross-section dimension of tunnels.