Applied Mechanics and Materials Vols. 90-93

Abstract: Combined with one foundation pit engineering in Guangzhou, the method was adopted in this paper, by which the in-situ test and finite element analysis were integrated. According to situation of study and demand of engineering, the study in composite soil nailing walls system was focused on working mechanism. The law of soil-nailing support technology for deep excavation was pointed out and summarized to provide reference to similar projects.

Abstract: Physical models of layered rock mass with different dip angles are built by physical model test in accordance with the bias failure characteristics of surrounding rocks of layered rock mass in Gonghe Tunnel. Bias failure characteristics of surrounding rocks in thin-layered rock mass and influences of layered rock mass dip angle on stability of tunnel are studied. The research results show that failure characteristics of physical models generally coincide with those of surrounding rocks monitored from the tunnel site. The failure regions of surrounding rock perpendicular to the stratification planes are obviously larger than those parallel to. The stress distributions and failure characteristics in the surrounding rocks are similar to each physical model of different dip angles. The stress distributions and failure regions are all elliptic in shape, in which the major axis is in the direction perpendicular to the stratification planes while the minor axis is parallel to them. As a result, obvious bias failure of surrounding rocks has gradually formed. The physical model tests provide reliable basis for theoretical analysis on the failure mechanism of deep-buried layered rock mass.

Abstract: Xiazanri Slope is a large-scale deposit slope located at the left bank of Liyuan hydropower station in Southwest China. The construction of the water intake there will form a very high excavation slope. Possible failure modes are analyzed based on geological conditions. Numerical simulation is conducted in FLAC^3D to obtain the deformation and failure characteristics of slope under excavation and normal water table conditions. Strength reduction method is used to obtain factor of safety. Results show the overall deposit is stable and attention should be paid to local parts.

Abstract: A new type of metal support named H-Shaped members with corrugated webs is put forward for the soft rock tunnels or roadways supports. The H-shaped member with corrugated webs is welded by corrugated webs and plain flange steel plates. The loading behaviors of the members are greatly improved by the corrugation in the webs compared with that of the members with plain webs. The new type of support has fair good mechanical performances with its own merits, including easy fabrication, fast construction etc. especially it can adapt to the large deformation of soft rocks. The elastic buckling behaviors are analyzed for the new horse-shoe shape supports with corrugated webs. The influences of the sectional parameters on the elastic buckling loads are discussed herein. Results show that the wave amplitude and wave height of corrugated webs have less influence on the buckling loads than those of the height of the webs and the width of the flanges etc. Some problems worth studying in the future for the new type of tunnel supports are also raised. Keywords: corrugated web; support structure; soft rock; tunnel; buckling

Abstract: Because the relationship is not considered between physical behavior and cross sections of bars, the conventional reinforced earth retaining wall design based on constant value would lead to some limitations: the haul-resistant coefficient of the top wall is not enough, but it goes beyond at the bottom of retaining wall. In the paper, considering the SARMA method, based on computing formula of traditional slope stability, the detailed programme is realized by the language of FORTRAN, it can make up deficiency that lies in the tradition reinforced earth retaining wall by considering the relationship of physical behavior and cross sections, lengths and layers of bars. Finally, the system program has been applied to a slope treatment project in Guangzhou. Compared with the design method of traditional regulations, it is demonstrated that the optimum length required is obtained, the cross section and length of bars are fully used, and the design is simplified.

Abstract: The theoretical defects of conventional Janbu method are systematically analyzed in this study. On the basis of these theoretical analyses, three inequalities are brought up to rationalize the results of inter-slice shear force, the point of inter-slice normal force and the point of normal force on slip line. The new iteration formulas of rationalized Janbu method are deduced and the process of rationalized upper bound solution is given out. The results of the example given in the end show that the rationalized Janbu method can distinctly improve the results’ reasonableness, and can work out the corresponding reasonable thrust line. And the results of rationalized Janbu method under given safety factor can provide relatively reasonable slipping force and slipping moment for reliability design of reinforcing slope.

Abstract: This paper presents the solution on the soft soil layer’s collapse of Xin Kailing Tunnel in China based on the analysis on its causes. The effect of the solution is evaluated by site survey and finite element analysis. The results show that the geological factor mainly leads to collapse; the crucial factor of preventing the collapse from happening is to give a better description of the tunnel face, to analyze and predict conditions of wall rocks which are in front of the tunnel face in time and to evaluate precisely whether the wall rocks and supporting system are strong enough or not; effective ways to solve the collapse problem is to strengthen supporting system of the being influenced parts in the tunnel, to seal wall rocks in collapsed possibly part as well as to add supporting system in time; the minimum safety factor of the solution in this project is about 3.1 which meets official standards of the tunnel construction; the solutions on the soft soil layer’s collapse of Xin Kailing Tunnel is effective, safe and reliable.

Abstract: Karst Water Bursting in Railway Tunnel is the main content of tunnel risk evaluation，there are lots of empirical factors in the actual work. Through the investigation on site, this study analyses Karst Tunnel on many respects, establishes the index system of venture evaluation on Karst Water Bursting Geological Disasters. Moreover, the concept of fuzzy information analysis is introduced to establish the fuzzy information analysis model, on the basis of information extraction of a large amount of geological disasters of Karst water bursting in Railway Tunnel, in which applied hierarchy analysis method to determine the weight of each index. Risk assessment on typical operating point shows that the risk evaluation method of fuzzy information can correctly assess the Karst water bursting disasters in railway tunnel.

Abstract: During the landscape design of the waterfront district, the designers often lack of full attention to the water environment problems and lack of system theory knowledge, so that some water environment problems (poor hydrodynamic, deteriorated water quality et al) will be emerged during long term operation of water landscape. For avoiding above problems, numerical simulation can be used in studies of water environment problems during the process of the landscape design. For explaining the application of the 3D numerical model, water environment problems above are studied in the Qilihai Lagoon, including flow field, water exchange and sediment deposition. The numerical model is tested validly by the measured dates.

Abstract: Study on temperature field and thermal stresses of a large volume concrete volute structure is important to prevent the concrete structure cracking caused by excessively tensile strains that result from the cold or heat waves and the internal water pressure. By use of the three dimensional finite element method, the displacements and stresses of a concrete volute under the external loads are calculated. The transient temperature field and the thermal stress distribution of the concrete volute caused by the cold or heat waves are obtained, and the thermo-structural coupling stress field analyses for some cases are completed detailly. The calculating results are the basis for the optimization design of the concrete volute structure.