Advanced Materials Research Vols. 446-449

Abstract: According to the mechanical properties of the parallel-adjective tunnel, the construction process is simulated and the displacements and concrete stress of the lining structure is monitored of an actual tunnel in the loess region. The influence which the new tunnel on the existing tunnel lining during the new tunnel construction process studied by comparatively analyzed the numerical simulation and monitoring the results. The results show that the impact on the existing tunnel during the new tunnel excavation changes with tunnel distance and the excavation method of the new tunnel, when the line distance increases the impact on the existing tunnel has been remarkably reduced.

Abstract: The similar material model experiment takes the NO.S2S9 coal face in DaPing coal mine as a prototype to research the characteristics of movement and failure of the soft overburden under fully mechanized top coal caving conditions. The abutment pressure distribution and periodic weighting, caving span are given by monitoring the stress and strain in the similar material model. The results show that rocks fracture extended from button with the advance of workface. The first caving step distance of main roof is 34m. The periodic caving step distance of main roof is 10m. The internal stress field is 10m and the peak abutment pressure point is 80m far away from the coal wall, while the disturbance range in anterior coal wall is 200m. Some cracks are closed in the later stage. The advance of around 300m is the distance that the water flowing fractured zone’s height reaches the highest value. The biggest height of water- flowing fractured zone is 140m. The soft overburden has strong plastic deformation capability. The synchronism of failure and movement of overburden is strong. The failured overburden is compacted and the cracks keep close with the advance of workface. The simulation experiment provides a reference bases for the application and promotion of thick seam mining technology.

Abstract: Firstly based on the practical problem of lining thickness built in porous rock aquifer with high water pressure, this paper introduce the mechanical and stable seepage model, and design formula of shaft lining named Baoshen; Secondly, the character of load and parameters in the “Baoshen” formula are studied, compared with the “Lame” formula and the original heavy earth field , which shows good universal feature to cover several traditional design methods. Thirdly, the principals of interaction among high pressure water, lining and surrounding rock are revealed by figure and discuss on inequality inequation; With a newly application example, the practical usage are introduced and newly viewpoints are opened to designers with material promotion, arrangement of re-bar or bolt, structure optimum etc.

Abstract: Soft rock; Anchor bolt-net-spray support; Twice support; Large section; Numerical simulation

Abstract: Three-dimensional finite element model of the mine escape capsule is established. With the different values of explosion shock waves, simulation analysis of the entry locker is performed by using ABAQUS. The simulation results indicate that the mine escape capsule is safe and available if the surge pressure of shock waves is less than 3.5Mpa.

Abstract: The pipe model is simplified as elastic foundation beam model of Euler-Bernoulli in the paper. Considering the effect of fluid flow in the pipe and outer soil constraint, the transverse vibration differential equation of buried pipeline is derived by using of Hamilton principle. By utilization of the first three-order modal and the orthogoality of main vibration mode, the equation is deduced and transformed into state formulas. The typical numerical example is analyzed by Matlab software. It is found that the natural frequency of pipe conveying fluid usually decreases along with flow velocity improving and the effect of foundation on the pipe stability is apparent.

Abstract: Many problems and dangers are brought forward during the construction of tunnels and they can be identified to the ground deformations around the tunnels. A large number of methods are proposed to predict the ground movements due to tunneling and some of them are proved to be effective in engineering practice. The state of the art on the prediction is reviewed, including Peck curve, analytical solution and numerical simulation. Some new approaches, such as artificial neural network and centrifuge model test are also referred.

Abstract: The settlement of ground and vault by tunneling has important effect on construction safety and normal operation of urban transport system. The soils around reserved shaft of Beiwan region in No.1 section of Beijing Metro Line No.7 are backfilled and complex. In order to tunnel safely and keep surrounding structures safe, the stability of rectangular transition section by tunneling of Beiwan horsehead region is analyzed. Based on the data of surface survey, drilling, prediction detection of the strata and engineering design, the software of 3D FLAC is used to study the vault and ground settlements during the excavation of six pilot tunnels of rectangular transition section, and the results are also compared with the results of in-situ monitoring. The research shows that the results of numerical simulation and in-situ monitoring are matched very well, the ultimate ground settlement will be 17 mm when the transition tunnel is excavated by non-shrinkage (WSS) pre-grouting method and CRD method, and meets with the requirements of standard specification. Therefore, the six-pilot-tunneling method is good for keeping the transition tunnel stable.

Abstract: Bolt has been used widely in geoengineering all over the world in recent years, the testing technique of bolt develops quickly too. This paper summarizes simply the history of bolt testing technique, describes in detail stress wave reflection method. It is useful and valuable nondestructive.Testing method is verified with several parameters which estimate quality of bolting integrity.

Abstract: In this study, a regional standard practice in the construction of the subway stations and tunnels for the study, with the SES software, a mathematical model of the closed system, platform screen door (PSD) systems, hybrid air conditioning system (adjustable ventilated platform doors [1]) to run the program properly simulate the conditions. Analysis of annual energy consumption of each system to be; while the traditional mode of operation of the system to explore and optimization; ventilation and air conditioning system for the new subway rational design and operation and management of scientific data to provide valuable information..