| 초록 |
Cohesive soil of Quaternary age, in particular of middle Pleistocene or later age, may be due to significant deformation and surface settlement in response to tunneling. In the excavation of a tunnel of about 900m long through this type of soil, tunnel deformation and surface settlement were strongly controlled by the soil strength properties, which were correlated with the N-value of the standard penetration test obtained during test drilling. This confirms that these soil properties can be used for the prediction of deformation and the control of measurement at site. During the excavation, a prominent fold zone, presumably caused by horizontal compression, and an associated shear zone involving a right-lateral strike-slip fault movement of 80m were encountered. This kind of observation is rare in Quaternary formations. In the studied soil, fine cracks developed by deformation further increased deformation and surface settlement. As a result, the deformation properties of the soil could not be predicted only from the N-value and strength properties. The modulus of deformation decreased with rock quality designation (RQD), a parameter used in core boring. This implies that the deformation properties of cracked soil can be predicted by using RQD together with the N-value. |
