Abstract A lot of shattering loose rock masses were created by the Wenchuan earthquake. In order to rationally evaluate the classification of the surrounding rock of newly built tunnels in these mountain areas, this paper analyzes, by way of site investigation, the features of shattered rock masses and their effects on the stability of surrounding rock. The shattered rock, which exhibits a more developed structural plane and poorer joining of interlamination after the effects of an intense seismic wave, has different features concerning hard rock and soft rock. The shattered hard rock is prone to centralized tension fissures and loosening, and the soft rock is prone to the volumetric deformation of loosening. Based on this, a three-level classification of shattered rock masses is proposed, e.g. slight, moderate and intense. In addition, a revision program is presented in which the level of the classification is not lowered or only lowered by 0.5 for the slight shattered rock mass since it has little impact on the stability of the surrounding rock; the level of the classification is lowered by 0.5 to 1 for the moderate shattered rock mass since it has adverse effects on the stability of the surrounding rock; and the level of classification is lowered by 1 to 1.5 for the intense shattered rock mass since it has extremely adverse effects on the stability of the surrounding rock.
Abstract：
A lot of shattering loose rock masses were created by the Wenchuan earthquake. In order to rationally evaluate the classification of the surrounding rock of newly built tunnels in these mountain areas, this paper analyzes, by way of site investigation, the features of shattered rock masses and their effects on the stability of surrounding rock. The shattered rock, which exhibits a more developed structural plane and poorer joining of interlamination after the effects of an intense seismic wave, has different features concerning hard rock and soft rock. The shattered hard rock is prone to centralized tension fissures and loosening, and the soft rock is prone to the volumetric deformation of loosening. Based on this, a three-level classification of shattered rock masses is proposed, e.g. slight, moderate and intense. In addition, a revision program is presented in which the level of the classification is not lowered or only lowered by 0.5 for the slight shattered rock mass since it has little impact on the stability of the surrounding rock; the level of the classification is lowered by 0.5 to 1 for the moderate shattered rock mass since it has adverse effects on the stability of the surrounding rock; and the level of classification is lowered by 1 to 1.5 for the intense shattered rock mass since it has extremely adverse effects on the stability of the surrounding rock.
MENG Lu-Bo,
Li-Tian-Bin,
Zeng-Zhi-Fa etc
.Discussion of Surrounding Rock Classification for Tunnels in Shattered Rock Masses[J] MODERN TUNNELLING TECHNOLOGY, 2012,V49(1): 27-32
2012, Vol. 49 