| Along with the rapid development of the national economy of our country, the highway construction is flourishing in our country , and national highway network structure is formed. By China's road network has made great achievements, China's highway tunnel construction ushered in the climax of building. As the tunnel complex geological environment, obtain accurate rock parameters and design parameters such as load data extremely difficult, in a very long historical period, the tunnel project designed mainly from empirical judgment. In recent years, as China's transport departments invested a large amount of funds for scientific research and large-scale underground construction, promoting rock mechanics theory and the construction of the tunnel, and in the process generated a lot of new construction methods and control survey technology.Highway tunnel with the feature of large span, excavation section, therefore, in order to guarantee the safety of the tunnel construction, during the construction of the tunnel, construction monitoring-feedback-control projects in various stages of construction information technology has to be widely used, which measured the scene monitoring the tunnel surrounding rock displacement, deformation and component stress, strain, then by feedback to control and adjust excavation or supporting lining rate and the intensity of support, as well as effective optimizing support parameters, to realize the highway tunnel for safety and quality construction.Currently in tunnel construction, the NATM has become the main method of highway, railway tunnel construction. The method is the application of rock mechanics, and using anchor and sprouting together as main supporting method. Construction through construction monitoring, timely and accurately understanding the evolution of rock, effectively judging the stability of rock, has a very important role in selecting a reasonable support time and optimizing lining;and through physical changes taking corresponding measures to predict roof fall, rock burst or collapse. On the prevention of accidents and ensure project quality of the project also has a very important role.This paper rely on Sha zi ya tunnel construction project on Ya lai highway. Using the NATM survey technology and methods, from construction monitoring planning and design, the basic principles and requirements, monitoring data processing and survey and analysis of feedback information on several aspects of this tunnel survey and control information feedback of the study.First control the planning and the principles of survey requirements, which determine the Tunnel of Sha zi ya control project will test the content of survey which is necessary and which is selection. The necessary survey of the project including measure the displacement of caverns surrounding, measure the sinking of the top arch; the selection survey including measure the sinking of the surface, the axial force of anchor and steel frame internal force. After the survey determined, in accordance with the project requirements and actual case, select the precise level and other instruments to make surveys, meanwhile according to the norms requirement determine measuring points and the monitoring section of the specific location.Secondly, during the construction process followed the survey point and section selected, according to the survey project and implement construction monitoring, also measured results of the analysis in a timely treatment. After detailed observation of working face of the tunnel, rock and supporting project, then determine tunnel entrance rock asâ…¢rock, and there were varying degrees of weathering. All kinds of rock in tunnels made initial support more flattened surface and coatings surface has no fissures or stripping, steel exposed without buckling phenomenon. Monitoring the implementation of the survey process, found K193+055~K193+080 and K193+110~KI93+140 of caverns convergenceand the surrounding Vault was significantly larger, surrounding rock deformation curve, has a larger-bending points unusual circumstances, and increase measuring point in the volume and frequency of the measured accurately predict the occurrence of landslides and avoid accident. Through surface subsidence surveys, getting the subsidence changing with time curve, from the curve can be seen absolutely sinking is small, sinking rate remained at a lower level and become stable gradually; which show subsidence has been basically stable. Drawing strength bolt-test results show bolt-drawing force to meet the requirements. Through the survey of axis force of arch, getting the axial force be with time changes plans and the axial force curves, from the graph, we can see that the anchor in the left top of arch has larger force, the largest rally for 19.85kN, the anchor in the right top of arch has smaller force, the anchor in top arch basically no stress, which show that loose rock circle on the right side of the top arch, and increase the anchor appropriately in the left is necessary. Steel Arch test results should show strength steel arch in a stable condition, then the rock in a stable condition can be determined.Finally from this paper, the construction monitorings of Sha zi ya tunnel were summarized with the following main conclusions:1.Through the construction monitoring and data analysis of Sha zi ya Tunnel, having a full understanding of the surrounding rock and the supporting structure state. With a scientific attitude to master the tunnel construction, to determine secondary lining of the time provides a reliable scientific basis, construction of security provided favorable protection.2.According to the survey data we can have a regression analysis, the best regression equation, from which we can predict the ultimate rock deformation. And combining survey from the total value of convergence with the surrounding allows deformation compared to the supporting judgment, and tests the supportingwork state and surrounding rock stability. According to the tunnel surrounding rock displacement rate to predict the tunnel landslide is an effective means. But in the landslides and the sudden large deformation section, rock deformation of the regression analysis is meaningless.3.the measured data analysis results showed that the top arch sinking and the surrounding convergence can be achieved the space of the tunnel deformation of good monitoring, Survey data can be reflected in the law more reasonable representation of rock deformation and trends. From construction monitoring results, except the landslide section, the items were measured within a month are moving toward stability, which show that Sha zi ya Tunnel of the initial support parameters basically correct, the method feasible.4.From the scene construction monitorings, determine the Sha zi ya tunnel lining in the timing should before have a proper rock deformation and loose damage, as far as in the process of the small deformation period surrounding rock deformation.5.By the impact of bias force, selection project section lumbar arch around the department and bolt steel Arch axis of the survey results of the large difference. Timely feedback surveys results, and warning landslides section, which can ensure the safety of construction, played a guiding construction and the purpose of optimizing the design.According to the process of measuring shortcomings the following proposals is raised:1.From the construction monitoring data, the measured data are sometimes relatively small; it is recommended that have a study of the first time after the excavation of rock dynamics, to avoid unexpected accidents.2.In order to have a more precise forecast of the project, we make our construction monitoring using different measuring methods and measuring instrument, and have comparative studies.In the construct of Sha zi ya Tunnel projects, we apply the NATM on the construction monitoring. Feedback information, especially statistical analysis the displacement information. According to the experience feedback and regression analysis, aggregate the rock and tunnel structure deformation and the law of force, confirmed the stability of the tunnel and rock structure, determine reasonable supporting timing and supporting parameters, and on the basis of ensure the safety of construction to pursuit economic. Through the scene construction monitoring and feedback information, on the safety of the tunnel construction provided important technical support and theoretical guarantee; meanwhile for the optimization of the tunnels design parameters and design changes to provide a reliable basis for the technology. |
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