A method to construct a main hole structural plane model based on advanced parallel adit geological body

Abstract

Abstract The advanced parallel adit of tunnel refers to the adit parallel to the direction of the main hole. Generally it is spaced tens of meters from the axis of the positive hole. During the tunnel construction, the parallel adit is driven before the main hole. Main function of it is to provide geological reference for the subsequent excavation of the main hole. At the same time, it can also help improve the long-term construction and operation and maintenance efficiency of the main tunnel. In terms of providing geological prediction information for the main tunnel, the surrounding rock information disclosed in the advanced parallel adit excavation is mainly used for surrounding rock classification and geological sketch, so as to qualitative analysis the possible geological conditions when the positive tunnel is excavated near the distance where the advanced parallel adit is located. However, the above methods cannot accurately and quantitatively analysis the geological conditions that the main tunnel will face. The lack of research on the correlation between the main tunnel and the advanced parallel adit geological conditions results in the waste of the key factor of the horizontal geological information.In this paper, the improved DBSCAN clustering algorithm is used to group the dominant structural planes according to the attitude of rock and other information. Some non-primary structural planes are screened out. The average distance between the same group of structural planes is calculated according to the average attitude of the dominant structural plane. The structural planes that are close enough are fused. Then, the axial and radial projection was carried out to form a larger range of surrounding rock fracture models. When the main tunnel is excavated to the relevant area, the situation of the surrounding rock in front can be predicted according to the model, so that the countermeasures can be made in advance. The method in this paper is applied to a tunnel project with bidirectional single line and advanced parallel adit. The prediction results after tunnel excavated show that the method in this paper is reasonable and effective.