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Qiu M.,shanxi Railway Vocational Institute | Jiang A.,Xiamen Rail Transit Group Ltd Corporation
Modern Tunnelling Technology | Year: 2013

In light of the principles of fluid mechanics, the limit equilibrium method, and the rheological behavior of rock mechanics, a method for calculating backfill grouting pressure and the flow characteristics of grout distribution are discussed. The grout pressure distribution was analyzed using the Newtonian fluid model and the Bingham fluid model, and a formula for horizontal grouting pressure distribution was deduced and an empirical formula for grouting pressure is put forward in this paper. Based on engineering practice, a comparative analysis was carried out regarding the Newtonian fluid model, the Bingham fluid model, and the empirical formula. The results show that the grout pressure distribution solution deduced from the Newtonian model is a special case of that deduced by the Bingham model; the grout pressure distribution is related to such factors as grouting pressure, shield tail void, driving speed, and grout property. The deduced grout pressure distribution model presented can be applied to concrete engineering calculations. Source


Qiu M.,Central South University | Yang G.,Central South University | Jiang A.,Xiamen Rail Transit Group Ltd Corporation
Shenzhen Daxue Xuebao (Ligong Ban)/Journal of Shenzhen University Science and Engineering | Year: 2015

This paper deals with the circumferential simultaneous grouting process by the tail of the tunnel boring machine (TBM) tail in practices of subway tunnels constructed by TBM. We establish the mechanical model of grout pressure at any point in the circumferential section, and derive the unified computation model of grout pressure distribution during circumferential filling by assuming that grouts are Bingham fluids. Then, using the basic principle of mechanical model and limit equilibrium method, we extend the computation model to multiple holes grouting. The grout pressure distribution model is verified by an engineering case. The analysis results indicate that four-holes grouting is suitable for smaller diameter tunnel, and six-holes grouting or multiple-holes grouting are good for larger diameter tunnel. Grouting hole position, TBM tail interspaces, and section flow have important impact on grout pressure distribution and thus deserve much attention in tunnel engineering. ©, 2015, Editorial Office of Journal of Shenzhen University. All right reserved. Source


Jiang A.,Xiamen Rail Transit Group Ltd Corporation
Modern Tunnelling Technology | Year: 2015

In this paper, using a shield tunnel in water-rich sandy ground as the study object, a mechanical model of shield thrust is established, with a focus on five influential factors, i.e., front additional thrust, friction force between the cutterhead and soil mass, friction force between the shield shell and soil mass, ground loss, and synchronous grouting pressure at the shield tail. Based on the Mindlin solution, a 3D analytical solution to ground deformation, which considers the influence of synchronous grouting pressure and cutterhead friction force, these factors are derived and verified by in-situ monitoring data and numerical analytical results. Analytical results show that curve of transverse ground deformation by shield tunneling presents in a "V" shape and the curve of the longitudinal deformation is an "S" shape, the left and right sides of the ground deformation curves concerning the friction force between the cutterhead and soil mass are antisymmetric, and ground heaving may occur due to synchronous grouting pressure at the shield tail and can be effectively controlled in time by grouting under the appropriate grouting pressure. The results obtained from this study are reasonable and suitable for predicting ground deformation during shield tunnelling. ©, 2015, Editorial Office of "Modern Tunnelling Technology". All right reserved. Source


Ge X.,Nanjing Hydraulic Research Institute | Su W.,Xiamen Rail Transit Group Ltd Corporation | Lu C.,Nanjing Hydraulic Research Institute
Advances in Science and Technology of Water Resources | Year: 2015

In order to improve the durability of frost resistance of hydraulic concrete under climate change conditions, a climate simulation system made by the authors was employed to study the effects of freeze-thaw temperatures on the weight loss and dynamic elastic modulus of hydraulic concrete with the three designed antifreeze levels F50, F100, and F300. During the test, the freeze-thaw processes were observed with set five center temperatures of concrete samples: -5℃, -10℃, -17℃, -30℃, and -40℃. The results show that, with decreasing center temperatures of samples in the freeze-thaw processes, the weight loss and dynamic elastic modulus loss of the three designed antifreeze levels gradually increase, while the maximum withstanding numbers of freeze-thaw cycles gradually decrease. That is to say that lowering the center temperatures of concrete samples in freeze-thaw processes will decrease the durability of frost resistance of hydraulic concrete. ©, 2015, Editorial Office of Journal of Hohai University (Nature Sciences). All right reserved. Source

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