Advanced Materials Research Vols. 594-597

Abstract: The high-temperature tunnel at Buren mouth - kongur Hydropower in West Kunlun Mountains of Xinjiang, China exist significant temperature differences phenomenon, which affects the stability of the shotcrete layer in tunnel. Combining with on-site engineering practice, the insulation heating device is designed. The laboratory splitting tensile strength test is carried out on polyester concrete, polypropylene concrete, polyacrylonitrile concrete and ordinary concrete with thermal heating device at 25°C-90°C. The splitting tensile strength changes of concretes affected by temperature difference are analyzed. The results supply a directly guidance to the design of the concrete sprayed layer structure of high-temperature tunnel.

Abstract: Based on Sidoroff isotropic elastic damage model, the damage deterioration constitutive equation was constructed for rigid and brittle rock mass. The excavation numerical simulation of a diversion tunnel with large section in Jinping hydro station was carried on. The displacement and stress evolution was analyzed considering stress transfer and dissipation of the tunnel surrounding rock mass. The stability evaluation parameters were put forward such as stress relaxation coefficient of surrounding rock mass, safety factor, the scale and distribution of plastic region of surrounding rock mass. The rock burst predication index was presented in viewpoint of energy such as sub-range statistic average energy release rate and sub-range statistic failure volume. The excavation methods for the diversion tunnel with large section were evaluated with multi criteria and the guideline for large section cavity in high in-situ stress was summarized.

Abstract: With the pace accelerating of development of urban rail traffic in large and medium-sized cities, urban subway and railway lines need to construct shallow and large-cross section tunnels and especially large-cross section tunnels. Large-cross section tunnel constructions make big influence on the surrounding buildings, roads and environment. How to build underground tunnel fast and safe in the downtown has become an problem which needs to be solved urgently. This article is for the technology of city large-cross section and shallow buried-tunnel, relying on the phase 1 of rail transit no.2 in Changsha, which combined with construction characteristics of the excavation method, double-side-wall method and step method, numerical simulation analysis on influence of the large-cross section tunnel disturbance in the surrounding rock, and provides the necessary technical support.

Abstract: At present domestic tunnel construction, dust is one of the main factors which impact the production efficiency, safety clean production. It not only pollutes the environment, but also threats the health of workers. This article start from the tunnel dust prevention, control measures, heading face negative pressure control dust, and spray jet with the dust, to do research about the mineral water jet dust negative pressure technology. Combining experiments and field test methods, Study the dust fall mechanism of the tunnel water jet vacuum dust suppression, the device parameters and the effect of dust, the application of the technology has great significance to reduce the dust concentration of tunneling face and improve the working environment of workers.

Abstract: Applying visual performance method, use reaction time measurement system to measure the small target which randomly appears inside the tunnel and analyse the measured data processing results then obtain the relationship between reaction time and the inner wall material、tunnel light and background luminance. We hold that human eyes on different luminance levels in tunnel lighting and visual characteristics of reflection reflection materials obeys Purkinje phenomenon. According to the visual performance theory, we put forward that reflective material assisting tunnel lighting will achieve good effect in energy saving. The study on reflective materials applied in tunnel lighting energy saving play an important guiding significance.

Abstract: This paper endeavors to analyze road lighting quality with the influence of luminous coefficients of the tunnel wall, with lighting design software DIALUX which simulates tunnel lighting, by improving the reflection coefficient of the tunnel wall materials. The result of Analysis shows that high-tunnel side wall reflection coefficient not only helps to improve the tunnel intensity of illumination, but also improves the luminance of the tunnel; under certain circumstances of the road surface luminance, high reflective coefficient of the tunnel walls is helpful to tunnel lighting energy consumption reduction.

Abstract: Use FLAC 3D finite difference software for numerical simulation and static calculation of the different models. Study the deformation and forces condition of different model during the process of excavation. The results show that setting invert of highway tunnel in Ⅳ1-grade rock section can improve the stress state of the supporting structure and reduce the surrounding rock deformation effectively. At the same time, the flat bottom tunnel applying C25 concrete and grouting bolts could improve the integrity of surrounding rock below the tunnel sidewall. It is can be considered to cancel the setting of invert to achieve the purpose of simplifying the construction and design.

Abstract: The safety of underground tunnels is a key problem of large substructure engineering during excavation and design. A new method to calculate the general safety factor of underground multi-tunnel is put forwarded based on the strength reduction theory. By the way of reducing rock material strength parameters (cohesion strength C and friction angle φ) step by step, the general safety of tunnels is got when the calculated result of excavation simulation shows that the equivalent plastic strain of rock wall becomes connection exactly. Engineering application indicates that the method of underground tunnels strength reduction is very useful for analysis quantitatively the general stability of tunnels and design of substructure.

Abstract: Triaxial compression tests have been performed to determine the properties of the surrounding rock. The displacement and stress of surrounding rock have been analyzed according to Silin 2 at Yungui railway under three kinds of conditions: the initial state, excavation without supporting , and supporting after excavation.Plane strain FEM is established to analyze the stability of the surrounding rock. Contrasted the monitor measuring data,the results show that: the most unfavorable position in the tunnel is found at the ridge side of the arch; and the implementation of support to ensure the stability of surrounding rock, and the design of the early support approach to meet the safety requirements. The results have a certain significance for understanding the mechanical behavior of shallow tunnel in unsymmetrical strata

Abstract: According to the force problems caused by changing of structure forms of broad-column joints when using top-down construction method, this paper introduces the process of top-down construction method and design method of broad-column joint, using finite element software to analyze the stress of ring beam around broad-column joint, which is verified that adopting ring beam is safety and reliable, ring beam can transfer load and bear moment effectively, the strength of outsourcing column will be checked, finally it summarizes the characteristics of ring beam using top-down construction method.