Applied Mechanics and Materials Vols. 256-259

Abstract: Underground pipelines affected by pit excavation are a practical problem often encountered in city foundation engineering. The characteristics of soil-nailing wall supporting include simplify, convenience, and low cost which make it widely adopted. Using MIDAS GTS for the integrated modeling, and the affecting factors are studied in four aspects, including excavation depth per step, pipelines’ depth, the distance between the edge of excavation and pipe, and the elastic modulus of surrounding soil. Some valuable conclusions for construction practice are drawn.

Abstract: The self-developed finite element method has many advantages and good prospects to solve problems of underground engineering. The program is used to the simulation of the true tunnel, while it is embedded into self-developed algorithm. The results indicate that self-developed finite element method has many advantages and good prospects to solve geotechnical problems, and it can be used for quantitative analysis of underground engineering.

Abstract: When highway tunnel is on fire, obstruction of vehicles in the tunnel have certain effects on the spread of fire smoke and critical velocity. This paper made CFD studies on the critical velocities when the blockage is located in the upstream flow of the fire smoke. The effect of the distance between fire source and blockage as well as the dimension ratio was analyzed. The numerical simulation results show that the critical velocity in upstream obstructed tunnel is smaller than that in empty tunnel and the critical velocity increases with the distance between the blockage and the fire source. The critical velocity increases with the heat release rate and decreases with the dimension ratio. The calculating model for critical velocity of empty tunnel was modified to adapt to obstructed tunnel.

Abstract: Various problems such as sand, mud and water bursting, unstability of tunnel face, large deformation of surrounding rock and severe cracking of primary support occurred in excavation of the water-bearing weak sandstone strata of Huma Ling Tunnel, Lan-Yu railway. Based on the uniaxial compressive strength tests and uniaxial compressive rheological tests on weak sandstone with water content of 0, 2%, 5%, 8% and 12%, the relationship between rheological characteristic and water content of water-bearing weak sandstone is obtained. According to results of tests, factors and water contents are fitted by applying generalized rheological equation of Kelvin. And the rheological equation of water-bearing weak sandstone with various water content is deduced. The test results and conclusion can offer reference for analyzing deformation characteristics and instability mechanism of water-bearing weak sandstone in large cross-section tunnelling.

Abstract: Through to the Henan tunnel engineering and observation hole, peripheral displacement measurement, measurement of subsidence of arch roof and surface subsidence measurement on-site real-time dynamic testing, obtained their changes over time curve, and the tunnel monitoring results were analyzed, thus improving the tunnel design and correctly guide the construction, ensure the safety and economy of the tunnel engineering.

Abstract: In order to solve the problem of design and construction of pavement structure in the long tunnel, through the analysis of pavement using domestic and overseas, combined with the factors of primary carrying capacity, small temperature gradient in the long tunnel, the Continuously Reinforced Concrete Pavement(CRCP) is proposed, which has characteristics of better durability, strong structure integrity and comfortable driving. Mini excavator auxiliary framing construction, layered pouring concrete, lap joint construction of welded steel have solved a series of problems of the relatively small space of construction, the lower concrete vibrators affected by the steel mesh and reinforced scene lashing. So continuously reinforced concrete pavement using welded steel fabric can be used as a major road structure in long tunnel.

Abstract: With development of coal mining technology and equipment, the coal roadway section size increases gradually, making roadway more difficult to support. In the paper, the supporting of large cross-section roadway in Hedong mine is studied and roadway excavation supporting process is simulated by FLAC3D. Coal roadway deformation and the problem of original supporting scheme are analyzed including displacement field, stress filed and plastic zone. Several supporting optimizations are proposed combined with site investigation and simulation analysis. And the optimizations are simulated and calculated. By comprehensive comparison, the optimal supporting scheme is obtained and some supporting law in large cross-section roadway is concluded. These are helpful for supporting design in future.

Abstract: Mechanized mining of Longwall top coal caving mining method was used in 1201 work face of thick soft coal seam in Du Jiacun Mine. The face is back to the wind drift along the seam floor excavation, transport drift along the seam roof boring the two crossheading basic fullcoal roadway, due to the relatively soft coal body, joints fractured, coal strength is low, and the coal-rock inclination, roadway section, the weakness of the surrounding rock rock, resulting in the excavation and support difficulties. This chapter based on numerical computation FLAC3D large-scale numerical analysis software, on the inclination special soft coal seam using a different roadway, support method, numerical simulation analysis of the support parameters, the contrast in different roadway support system support parameters, the deformation of surrounding rock displacement, stress distribution, the distribution of plastic zone, the big dip is extremely soft for Du Village coal mine mining Gateway support programs, and through on-site ground pressure observation of program verification.

Abstract: Slope safety has been well concerned by the society in recent years. Slope displacement monitoring is an important subject of slope safety and its research has been developing rapidly. In this article, we draw up a pilot slope safety automatic monitoring scheme for the project of Road No.1 in Republic of Congo, which depends on real-time displacement monitoring. This scheme uses fixed inclinometer as its main appliance and achieves wireless data transmission. During this process, we considered both local climate and the characteristics of high slopes along the road, and finished a series of work including monitoring position selection, critical slip surface prediction and finally monitoring system establishment. Our ultimate objective is to achieve real-time monitoring of slope situation, and furthermore set up the relationship among slope displacement, rainfall and time. With the derived relationship we would be able to forecast the development of slope deformation and possible danger caused by the slopes.

Abstract: The steel-belt has the ability to improve support effect of the whole system that coordinate the anchorage force of bolt or cable, improve the support effect of the anchor system and diffuse the fore acted on bolt or cable. During the progress of support in the roadway, there has appeared flat, W and M steel-belt, and all of them have played important roles in different stages of support in the roadway. However, steel-belt now is rarely used in the deep rock roadway. High convex steel-belt is a new product, but whether it can adapt or not to the deep roadway, it's well worth our attention. The structure of high convex steel-belt and the characteristics of deep roadway are introduced in this paper. Numerical test on four kinds of mine steel-belt is carried out by ANSYS, and the advantage of high convex steel-belt is comparatively analyzed in deep roadway. At last, an example is shown. Research indicates that the steel-belt bears mainly the point load or local load due to non smooth and even convex wall sides, and it lies in a state of inelastic and large deformation due to non uniformity deformation of surrounding rock in the deep rock roadway. The mechanical behavior of convex steel-belt has the performance of obvious advantages. It can adapt to the large deformation of deep roadway due to the convex structure. This result has been proved in the engineering practice.