Ground Settlement of Deeply Buried Two-Lane Tunnels with Large Cross-Sections Using Different Construction Methods

Abstract

To ensure the safety of excavations such as large section tunnels of the Guangxi Liubin Highway Tunnel Project, we implemented a simulation analysis of 3D tunnel models based on finite software for different construction methods. Different from the traditional simulation, this paper uses various construction methods to compare, study, and analyze the advantages and disadvantages of different excavation methods by combining them with the excavation. The feasibility of different construction methods was analyzed by studying the mechanical characteristics and settlement changes using the Cross Diaphragm (CRD), Center Diaphragm (CD), and full-section methods while building a large section tunnel. The arch perimeter deformation and surface settlement during the initial support and secondary lining proved that the CRD excavation method is the most favorable and causes the least damage to the stability of the surrounding rock. For the analysis of surface subsidence, the “V”-shaped surface subsidence curve excavated by the CRD method is the closest to the subsidence curve. However, we used the adjusted peak formula to fit the prediction formula for the surface settlement curve of the deep-buried two-lane tunnel with a large cross-section applicable to this project, which will provide an important reference for similar projects.

Study on Aeolian Sand-Box Backfill Geomechanical Characteristics and Overlying Strata Control Effects

“…To assess the suitability of aeolian sand-box-type backfill for filling mining under different coal seam conditions, this section examines the control effect of various As shown in Figure 15, during coal seam mining using the caving method, the displacement of the overlying rock layers above the coal seam primarily exhibits a trapezoidal distribution, which is in line with the typical pattern of overlying strata displacement. This observation aligns with the findings of other researchers [33][34][35]. The collapse of the overlying strata above the coal seam intensifies with the progression of the working face.…”