Applied Mechanics and Materials Vols. 170-173

Abstract: Taking Motianling tunnel in Chongqing as an engineering background, the monitoring and measurement scheme is proposed for the extra-long tunnel under complex condition, and the field data and the numerical simulation results is analyzed. The results indicates that, the selected cross-section reflect overall state of the Motianling tunnel, and the structure safety monitoring during operation is considered; by tunnel internal and external observation, it is found that the tunnel face in F22 fault zone may not stay stability, because the monitoring information receive feedback timely, and the supporting measures is proper, the surrounding rock stay stability when excavating; for the typical section, the surrounding rock contact pressure is greater than interlayer pressure, primary lining sustains most of the load ,and the secondary lining plays an assistant role as safety reservation; the maximum of anchor axial force and surrounding rock pressure occur at tunnel crown. By monitoring and numerical simulation, the dynamic excavation and design is realized, the Motianling tunnel is achieved safely and successfully at last.

Abstract: Utilizing the basic theory of heat transfer and computational fluid dynamics and considering the coupling influence of air in the channel and tunnel surrounding rock, the paper deduced control equation of hydrokinetics, calculated the formulas and made secondary development program applying UDF language on ANSYS FLUENT as a basis. Based on materials of Fenghuo Mountain tunnel, the paper analysis for coupled problem of heat transfer of surrounding rock and heat convection between air in cold region tunnel and surrounding rock, and comparative analysis of the annual average temperature between the calculation result and the actual observation records in 2004. The results demonstrated: in the laminar flow condition, the annual average temperature of the cross-section of tunnel entrance and exit is the same as or higher than the tunnel inside. In the turbulence fluid condition, the annual average temperature diminishes from entrance to exit, and there exists mutation between the cross-section of entrance and exit and other cross-section. When air flow state is assumed to be laminar inside Fenghuo Mountain tunnel, the calculation result and the actual observation records are the same. Assumed to be turbulent, both of result are different. Therefore, the calculation depend on the actual corresponding air flow state in tunnels in cold regions designs. The paper results will be providing the theory base and reference of design, construction and study of tunnels in cold regions.

Abstract: Road tunnel surrounding rock classification is the basis of choosing tunnel construction methods and designing support lining. Both in domestic and foreign countries, there is a wide variety of classification methods, which the engineering analogy of more general use. Our national standard BQ method is a semi-qualitative and semi-quantitative engineering analogy classification method. Less due to its classification category, it is difficult to meet the construction needs. Therefore, with an example, three indicators which get a low correlation were used to divide level Ⅲ、Ⅳ and Ⅴ into different sub-levels by hierarchical cluster analysis method. The study is a complete and optimization on the existing road tunnel surrounding rock classification methods, and provides new guidance for the actual construction.

Abstract: With the growing demand for public transportation in big cities, metro construction is developed rapidly. It is much important to keep the adjacent buildings safe in the course of metro construction. In this paper, an effective method of evaluating safety of adjacent buildings influenced by metro construction in Beijing is suggested. It is composed with collection of related data, analysis of geotechnical condition, detection of building appearance quality, measurement of existing building, control standard of subgrade deformation and numerical prediction. Finally, an example is given to explain this method in detail.

Abstract: Dalian speed railway tunnel is located in complex soft rock and soil, the road foundation deform and surrounding rock stability control is a concern problem. Along with the unloading process of excavation, surrounding rock moving to inner hole, while exceeding the elastic limitation, the plastic deform and the surrounding rock destroy then occurred. The paper adopted three dimensional elastic-plastic method based on Mohr-Coulomb yielding criterion and carried out numerical simulation of excavation process, in order to analyze and compare the surrounding rock vertical displacement contour, ground surface settlement and damage zone corresponding to different construction sequence. The elastic-plastic numerical method can reflect the damage and destroy character of nonlinear soil material of surrounding rock corresponding to different construction scheme, the simulation result has active guiding meaning for the Dalian speed railway tunnel construction design and dynamic analysis.

Abstract: The adverse effect of tunnel uplifit on tunnel structural stability and waterproof property is increasingly prominent, leading to engineering problems such as segments connection and damage. All these bring the construction quality down and make it difficult for operations and management. Based on the data obtained from monitoring the upllifit of the serrid measure sections in two intervals in Ningbo metro line No. 1, this paper studies the segments uplift by analyzing segment mortise structure features and float upward trajectory. The article considers the worst conditions according to the size difference in mortise, puts forward a method to calculate and integrate the slab staggering and segments opening based on the monitoring data, and then get two float upward point values. Finally, it is proposed that by updating and fitting the monitoring data, the tunnel uplift can be divided into three intervals, making it possible for dynamic and hierarchical control. The research results could provide reference for the shield tunnel construction.

Abstract: The efficiency of our rock roadway is generally not high, January footage is generally around 60m, which greatly affected the normal mine production mining to succeed. Optimize the blasting parameters, support technology and strengthen the construction organization and management measures is to solve the Rock Lane embrasure low utilization rate, blasting the poor, loop footage and low problem. The experiments show that: the three new mines using the above measures, the rock roadway construction speed from the original 60 m per month to 120 m / month, improve efficiency of 100% quality and efficient excavation of the rock roadway to reach the test purpose. Of the success measures and methods to provide reference for other similar mine rock roadway quality and efficient construction.

Abstract: Based on Dalian subway line 2 from Chun-guang street station to Xiang-gong street station,the three dimensional finite element model was established using FLAC3D software , the shield excavated surface against the pressure, the stress release, the shield tail escape and grouting. The numerical result indicated that the pipeline displacement increases gradually with the advance of the tunnel excavation. When one-sided tunnel excavation is carried out, the largest displacement is located at the tunnel axis, the settling curve basically conforms to the normal distribution curve with the unimodal characteristic. The excavation of right-side tunnel is disadvantageous to the left-side tunnel. The analysis indicated that the pipeline is in a secure state. The work in this paper provided theoretical basis and the practical guidance to this project.

Abstract: In this paper, vehicle systems and track-tunnel system are regarded as an interactional, mutual coupling overall system and the interaction between wheel and rail is regarded as the “ligament” of these two subsystems. The vehicle vibration model and vibration equation are established by considering the body vertical vibration, a suspension of vertical vibration and wheelset vertical vibration. By the displacement compatibility condition of the vehicle and track, integrating the vehicle equations and discretized track-tunnel vibration equation, the dynamic coupling model and the equations that reflect the vehicle-track systematicness is constituted. It provides a reference for the further research of the dynamic analysis of vehicle-tunnel coupled system.

Abstract: This paper classifies the tunnel frost damages and discusses their causes, especially the causes of lining structural damage for freezing and they are classified into two categories: the outer freezing damage and the inner freezing damage of lining. The analysis shows that the former has a little effect on the structure, but the latter has big threat. For the phenomenon that cracks frequently occur in the tunnel lining of cold regions, some measures to prevent cracks are presented, including reducing adverse constraints in the process of temperature change and preventing large temperature stress. In cold regions, it is unsuitable to adopt back paste-type water-stops to prevent the leakage from lining construction joints, and a good choice is to utilize the buried drainage water-stops. The ring drainage pipes directly connect with the central drainage pipe, and thermal insulating layer with belt shape is set along the ring drainage pipes in some sections where surrounding rock is water-rich and the middle and lower part of the ring drainage pipe are easily frozen. In sections with high potential freezing threat, an anti-freezing plan is offered that electric heating wires are installed behind the lining wall. The test shows that above techniques have good effects in cold region tunnels.