Tunnel Construction,2019,Vol 39,No. 07
Tunnel Construction,2019,Vol 39,No. 08
Tunnel Construction,2019,Vol 39,No. 09
【Abstract】 In order to select a suitable ventilation scheme for a single-tube extra-long highway tunnel with two-way traffic, as well as to solve problems in smoke exhaust and personnel evacuation in such tunnel, 3 ventilation schemes are proposed. According to the characteristics of Zhagaliang extra-long highway tunnel, the 3 ventilation schemes include confluent ventilation with exhaust shaft and longitudinal ventilation with jet fans, parallel pilot tunnel forced ventilation network, and longitudinal ventilation with jet fans and sectional smoke exhaust by inclined shaft. The ventilation schemes are compared from several aspects, i.e., civil construction cost, initial investment of mechanical and electrical equipment, electricity cost during tunnel operation, ventilation control, stability of ventilation network, applicability, management and maintenance. Finally, the most suitable ventilation scheme is selected by comparing the advantages and disadvantages of each scheme, i.e., longitudinal ventilation with jet fans and sectional smoke exhaust by inclined shaft. Under the normal operation condition of the tunnel, longitudinal ventilation with jet fans is adopted in the main tunnel, and on-demand ventilation can be realized. Smoke can be exhausted by inclined shaft in case of fire, which can solve the problem of smoke exhaust only in two sections by the parallel pilot tunnel. The parallel pilot tunnel can also be used for personnel evacuation and rescue.
Progressive Failure Law and Control Criterion for Safe Construction of Shallow Buried Highway Tunnel with Different Grades of Surrounding Rock
China Journal of Highway and Transport,2019,Vol 32,No. 12
【Abstract】 Focusing on the progressive failure process and mechanism of shallow buried tunnels with large sections, we carried out model tests and in-situ monitoring. With Diantou Tunnel taken as the engineering background of this study, the stress and surface settlement of the surrounding rock of different grades (IV 3, V 1, and V 2) during tunnel excavation were analyzed. Consequently, a safety control index of tunnel construction based on differential settlement is proposed. The results of on-site monitoring verify the scientific nature of the index, ensuring the safety of the tunnel construction. Conclusions can be drawn as follows: ① The damage of the shallow buried tunnel begins from the vault. With the excavation of the different segments of the tunnel, the damage zone extends to the arch shoulder and the ground surface. The IV 3 surrounding rock has a stable collapse arch. The height of the collapsed arch is approximately 0.67 M ( M is the maximum span of the tunnel). The tunnel excavation can lead to the collapse of V 1 and V 2 surrounding rock and finally the collapse of ground surface, which can cause serious accidents such as landslides. ② During tunnel excavation, the tunnel has undergone different degrees of convergence and settlement caused by unloading in excavation. For the maximum surface settlement, IV 3 is 63.0% less than V 1; V 1 is 20.0% less than V 2; IV 3 is 70.4% less than V 2. For the maximum stress variation, V 1 is 43.5% less than IV 3; V 2 is 23.0% less than V 1; V 2 is 56.5% less than IV 3. The influence of excavation on stress and deformation of tunnels with surrounding rock is IV 3 < V 1 < V 2. ③ With the model test method, the ratio of the settlement difference to the measuring-point distance is calculated. Then, the control criterion for the construction of shallow buried tunnels with surrounding rock of the above three grades is discussed. As for the V 1 surrounding rock grade, the monitoring results show that when the horizontal and vertical deformation differences of the tunnel are less than 10 mm/m, surface cracks of the road can be prevented. Therefore, the research results are of great significance for the construction and safety control of shallow buried highway tunnels with large sections.
Tunnel Construction,2018,Vol 38,No. 04
【Abstract】 Aiming to solve the problems of collaborative management of intelligent tunnel and tunnel management under different traffic conditions, the tunnel is regarded as a part of highway, and five features of the intelligence are proposed from the definition of intelligence. In order to realize a collaborative management of intelligent highway tunnel, the spatial extent of tunnel is defined at first. Then, a collaborative management road topology based on road critical nodes is proposed;and a holographic collaborative control information system based on tunnel structure, facilities, vehicle, operation, management, and environment is established. Finally, collaborative control of people, cars, roads and environment could be realized, so as to improve the management level of the intelligent highway tunnels.
China Journal of Highway and Transport,2018,Vol 31,No. 04
【Abstract】 To solve the contradiction between energy saving and traffic safety with regard to the lighting environment of a highway tunnel, the problems and existing improvement methods of such an environment are analyzed, based on which, a simple sorting method is adopted to compare the sight guidance, protection, anti-skid, shading, and lighting facilities in terms of economy, durability, and construction difficulty. Moreover, the safety demands of highway tunnel drivers are analyzed according to accident causes. The results show that a visual guidance facility that can reconstruct the visual reference system of a highway tunnel is the first choice for optimization of the lighting environment. In a tunnel section, such a guidance system can effectively control the driver’s visual capabilities, meet the driver’s safety demands, and reduce poor driving behaviors and traffic accidents. Safety demands a sense of speed, distance, direction, and location. Retro-reflective visual guidance facilities are used to construct a safety visual reference system consisting of multi-frequency, multi-dimension, multi-shape, and multi-color information, which can strengthen the local brightness and contrast in a tunnel and improve the driver’s sense of speed, distance, direction, and position. A sight guidance system based on safety is suitable for a highway tunnel with low illumination. For low-grade highway tunnels without lighting, a guidance system can replace the lighting facilities. For high-grade highway tunnels with lighting, a guidance system can assist with the lighting facilities. Such a system can help realize a unification of energy saving and traffic safety in a tunnel environment.
Structural safety assessment technology of long highway tunnel based on fuzzy analytic hierarchy process
Journal of Natural Disasters,2018,Vol 27,No. 04
【Abstract】 In combination with structural design, structural status and disease, and maintenance, the special analysis of typical risk events of tunnel structure is carried out for structural safety during operation. At the same time, the evaluation index of structural safety of long highway tunnel is put forward, and the classification standard of tunnel evaluation index is established. The combination weighting method of multification scale method and entropy weight method is adopted, and the weight of each index in the index system is determined by combining the variable weight method. On the basis of this method, the analytic hierarchy process (AHP) and fuzzy principle are used. Finally, the evaluation system and classification standard of the safety level of highway tunnel structures are established.
Numerical simulation of mechanical characteristics of mountain road tunnel under frost heaving in seasonal frozen region
Journal of Natural Disasters,2018,Vol 27,No. 04
【Abstract】 The extreme low-temperature climate in the seasonal frozen region seriously threatens the operational safety of the tunnel, and the frost heaving effect of surrounding rocks is the external source for the tunnel’s freezing damage. With a highway tunnel in Jilin Province as an example, the dynamic distribution law of the surrounding rock freezing temperature field was simulated based on the transient heat transfer theory with phase transition. And the internal force and deformation characteristics of lining under frost heaving were calculated using Abaqus FEM model. The calculation results showed that the freezing of the surrounding rock started from the arch, developed to the side wall, and finally extended to the bottom of the inverting arch to form a frozen ring; the law of freezing depth distribution presented arch > sidewall > inverted arch; the freezing development speed was related to the change of temperature, and showed some hysteresis. After frost heaving of surrounding rock, the lining deformation exhibits the “horizontal duck egg-shape” shrinkage tendency, and the side wall convergence with uneven uplift of the inverted arch was impacted most, the stress concentration at the connection between the side wall and the inverting arch may affect the overall stability of the structure. In addition, the rotation of lining structure reached positive and negative peaks at 48° and 96° from the vault, which can be regarded as the sensitivity point under frost heaving and can be selected as the best point for rotation monitoring.