As a permanent tunnel support structure, the lining, due to additional load, rock defects, construction quality, and other factors that form a inhomogeneous load, can cause lining cracking and misalignment, severely influencing the stability of the tunnel. Therefore, based on the Lhasa-Nyingchi Railway Tunnel Group Project, theoretical analysis, on-site measurement, numerical simulation, and in-house test were used to study the deformation and damage evolution law of the tunnel lining under inhomogeneous load, determine the scope of treatment, and guarantee the structure's safety by using carbon fiber reinforced plastics reinforcement technology. The following results have been achieved:
(1) Determined the value and distribution model of inhomogeneous loads. The main loads in the “Railway Tunnel Design Specifications” were analyzed to summarize the types, values, and distribution models of inhomogeneous loads. Through the theoretical method to analyze the unspecified inhomogeneous load, according to the idea of solving Terzaghi’s surrounding rock pressure, establish the calculation method of surrounding rock pressure under the influence of non-continuous boundary conditions; given the limitations of the continuous accumulation of Terzaghi’s Theory, combining with the theory of interlayer mechanics, put forward the method of calculating the surrounding rock pressure under the influence of large inclination angle and rock strata, and parameterize the model by using Lhasa–Nyingchi Railway, and then systematically generalize and establish a model of taking value and distribution of inhomogeneous loads.
(2) The deformation and damage mechanism of circular arc lining under inhomogeneous load is revealed, and the scope of treatment is determined as well. Through the elasticity theory and load effect combination method, the stress model of circular arc lining under inhomogeneous load is established to reveal the relationship between stress and load, lining size and section coefficient, and the like. Through twin shear unified strength theory, the development model of deformation and damage of circular arc lining is established to examine the relationship between inhomogeneous load and damage location and range, to determine the critical value of load and damage model of each segment of circular arc lining and to verify the feasibility of the theory with the use of numerical simulation.
(3) The deformation and damage mechanism of multi-segment arc lining under inhomogeneous load is revealed, and the scope of treatment is determined. Based on the engineering parameters of the Lhasa–Nyingchi Railway, the unfavorable inhomogeneous load is determined, and the elastic internal force of multi-segment arc lining is solved by the force method. The plastic hinge and section coefficient methods are used to determine the plastic development coefficient of the internal force, to obtain the value of the destructive internal force of the multi-segment arc lining. The multi-segment arc lining is equivalent to a plane curved beam, and the plastic development model is established as well, so as to determine the control elements of the internal force, the damage location, and the scope of the treatment.
(4) Given the scope of damage and force characteristics, the corresponding carbon fiber reinforced plastics reinforcement treatment method is proposed, and the tunnel environmental impact parameters in the reinforcement process are determined. According to the force characteristics and damage situation of the damaged lining section under inhomogeneous load, the management level is divided, with the carbon fiber reinforced plastics reinforcement method proposed. For the environmental characteristics of Lhasa–Nyingchi Railway, freeze-thaw damage test, carbon fiber reinforced plastics slip test, and carbon fiber reinforced plastics reinforcement freeze-thaw/load-holding concrete strength test were designed, and relevant models were established combined with the strength of materials in the lining to determine the environmental impact parameters of the tunnel in the reinforcement process.
(5) Through the in-house model test and curved beam model, the calculation method of bearing capacity of carbon fiber reinforced plastics reinforced damaged lining under the influence of the tunnel environment is established, and the piezoresistive monitoring system is developed, which can grasp the force condition in time and guarantee the stability of the reinforcement. Through the in-house test of carbon fiber reinforced plastics reinforced damaged lining under the environmental impact of the tunnel, the change rules of bearing capacity, reinforcement parameters, structural damage, and environmental parameters, are revealed, with the improvement rate of bearing capacity determined. Based on the combined curved beam model, it puts forward the method of calculating the bearing capacity of carbon fiber reinforced plastics reinforced damaged lining under the environmental impact of the tunnel. For the situation of the damaged lining of Lhasa–Nyingchi Railway, it analyzes the carbon fiber reinforced plastics reinforced section load value, crack grade, management program, before and after reinforcement bearing increase rate, and again the change rule of pressure resistance, by means of simulation, theory, and monitoring, to ensure the stability of the reinforcement.
谷歌
火狐
