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Study on the Characteristics and Distribution Laws of Plastic Zone Induced by Deep-buried High-geostress Hydraulic Tunnelling in Jointed Rock Mass
(1 College of Water & Architectural Engineering, Shihezi University, Shihezi 832003; 2 Xinjiang Survey and Design Institute of Water Resource and Hydropower, Urumqi 830099)
Abstract The deep-buried high-geostress hydraulic tunnel is located in a complicated geomechanical environ? ment, and the distribution and evolution laws of plastic zone of surrounding rock during excavation are key to controlling tunnel stability. In order to reveal the characteristics and distribution laws of plastic zone during excavation of hydraulic tunnels with high-geostress, this paper combines theoretical analysis with numerical simulation, derives a calculation formula of plastic zone range, introduces a new dimensionless parameter to evaluate the plastic zone of surrounding rock in a non-circular tunnel, and analyzes the influences of lateral pressure coefficient and excavation disturbance on the plastic zone of jointed rock mass with high geostress. The study result shows that the axial development range of rock plastic zone affected by excavation disturbance is about 1.0-1.5 times the tunnel diameter, while the influence range can be 2 times the tunnel diameter for the rock mass with joint plane. It is concluded that the lateral pressure coefficient directly affects the shape of the plastic zone of the surrounding rock, with the tendency of irregular development of the rock plastic zone along the joint plane. The greater the difference between the horizontal stress and vertical stress is, the greater the influence range of the joint plane on the plastic zone of the surrounding rock will be. In addition, the joint plane can prevent the plastic zone from development along the vertical joint plane.
Abstract：
The deep-buried high-geostress hydraulic tunnel is located in a complicated geomechanical environ? ment, and the distribution and evolution laws of plastic zone of surrounding rock during excavation are key to controlling tunnel stability. In order to reveal the characteristics and distribution laws of plastic zone during excavation of hydraulic tunnels with high-geostress, this paper combines theoretical analysis with numerical simulation, derives a calculation formula of plastic zone range, introduces a new dimensionless parameter to evaluate the plastic zone of surrounding rock in a non-circular tunnel, and analyzes the influences of lateral pressure coefficient and excavation disturbance on the plastic zone of jointed rock mass with high geostress. The study result shows that the axial development range of rock plastic zone affected by excavation disturbance is about 1.0-1.5 times the tunnel diameter, while the influence range can be 2 times the tunnel diameter for the rock mass with joint plane. It is concluded that the lateral pressure coefficient directly affects the shape of the plastic zone of the surrounding rock, with the tendency of irregular development of the rock plastic zone along the joint plane. The greater the difference between the horizontal stress and vertical stress is, the greater the influence range of the joint plane on the plastic zone of the surrounding rock will be. In addition, the joint plane can prevent the plastic zone from development along the vertical joint plane.
HUI Qiang1 ZHANG Jun2 JIANG Haibo1
.Study on the Characteristics and Distribution Laws of Plastic Zone Induced by Deep-buried High-geostress Hydraulic Tunnelling in Jointed Rock Mass[J] MODERN TUNNELLING TECHNOLOGY, 2021,V58(4): 86-94
2021, Vol. 58 