การวิเคราะห์พฤติกรรมของอุโมงค์ในหินที่ก่อสร้างด้วยเครื่องเจาะอุโมงค์โดยวิธีดิสครีตเอลิเมนต์

Abstract

The objective of this thesis is to simulate a tunnel model constructed with a tunnel boring machine during construction and to analyze the behavior of the rock mass around the tunnel and the structure of the tunnel. From the project to increase the amount of water in the Mae Kuang Udom Thara reservoir in the Contract 1, Mae Taeng - Mae Ngad water tunnel by the Royal Irrigation Department Chiang Mai Province from the geological survey data at the entrance-exit number 2, all behavior was analyzed by the discrete element method using a three-dimensional model. With a focus on the study of rock mass behavior movement of tunnel structures, stress and strain behavior around the tunnel in the case that water has not sent into the tunnel yet. To be used as a guideline to control the behavior of rock movement around the tunnel, especially in the crown and side walls of the tunnel and the impact on the concrete components from the movement of the surrounding rock mass From the study of tunnel construction by tunnel boring machine, the construction can be classified into 4 steps which are 1) pre-construction step 2) Drilling process 3) Installation steps for precast concrete tunnel segments and step 4) to increase the stability of the rock mass around the tunnel by consolidation grouting. Therefore, the study begins with the process of installing the precast concrete segment as the field data with the motion measurements is done in the said construction process. In order to use it to create three-dimensional models using 3DEC in other construction steps, using data from the field. Resulting in a three-dimensional model that can be modified when needed for further use. From the processing of the tunnel construction model using tunnel boring machine. Has no vertical displacement at the tunnel ceiling position. Because the rock mass is in equilibrium stage in nature. Stress is distributed at the intersection rock joints and increases with depth. And has no strain occurs at this stage. In the process of excavation a tunnel. The displacement at ceiling is about 5.67 millimeters. The behavior is characterized by the movement of the down direction along the joint and the intersection of the rock mass. And there is a deflection on the ground of the tunnel And the behavior of major principal stress is concentrated on the walls of the tunnels that are dug and spread along the joints of the rock mass And there is a lot of strain on the ceiling of the tunnel. In the process of installing precast concrete components The highest movement is found at the ceiling and raised up at the bottom of the tunnel. The displacement is continue go further from the excavation step, And the displacement of ceiling is about 6.19 mm and the behavior of the major principal stress at the wall of the tunnel has slightly decreased. And strain on the tunnel ceiling slightly decreased after the installation of precast concrete components. In the process of improvement the stability of the tunnel, The direction of movement remains the same but there is only a small movement. The movement at the ceiling is approximately 6.21 mm. Stress - Strain does not change, because the rock mass has moves until it reaches the equilibrium point.