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Li S.-C.,Shandong University | Zhao Y.,Shandong University | Zhao Y.,Qingdao Metro Corporation | Li L.-P.,Shandong University | And 2 more authors.
Yantu Lixue/Rock and Soil Mechanics | Year: 2011

Tunnel excavation will lead to surrounding rock loose and exert certain load on the structure in the meantime. In the excavation process, the load of structure releases continuously in the stress adjustment process till the structure and rock mass stabilizing. Numerical analysis and model test are carried out to research the load releasing process of the whole section in the construction of ultra-large section railway tunnel. The load fluctuation rules of key points in bench excavation are studied firstly, then concepts of section comprehensive load release rate and difference coefficient of load release that characterizes the state of load release of the whole section are defined; and the load fluctuation rules in the process of construction are summarized via the two parameters. With monitoring of change laws of radial pressure at key points of rock mass in the geomechanical model test, the conclusions obtained by numerical analysis are testified; and the principle that the section must be regarded as a whole is realized to make the study of load release more comprehensive. Source


Zhihui L.,Shandong University | Qingzhi J.,Shandong Electric Power Research Institute | Hang C.,Qingdao Metro Corporation | Xuelong D.,Shandong University | Zhizhen L.,Shandong University
Applied Mechanics and Materials | Year: 2012

As the energy crisis becoming more and more serious, electric vehicles has become an important way to solve this problem. The difference of Popularity, type, charge time, charge style and charge characteristics of Electric vehicles make different effect on the Regional power grid, especially quick charge technology. In this paper, through the establishment of regional power grid model and the forecast of quick charge station load curve, we analysis the impact of charge station on voltage of the user side, furthermore, we analysis voltage loss and impulse current when the large power charger connected to the power grid, and verify the analysis by simulation. In order to reduce the impact on the grid, we should rationally plan the charge station and the reactive power compensation, thus enhance stability of power system. © (2012) Trans Tech Publications, Switzerland. Source


Du Z.-J.,University of Science and Technology Beijing | Du Z.-J.,Qingdao Metro Corporation | Gao Y.-T.,University of Science and Technology Beijing | Wang L.-B.,China Railway 16th Bureau Group Co | Du X.-W.,University of Science and Technology Beijing
Beijing Keji Daxue Xuebao/Journal of University of Science and Technology Beijing | Year: 2011

Aiming at analyzing the tunnel excavation problem in representative silty clay stratum in Beijing, triaxial consolidation drainage tests were carried and the mechanical characters under different stress paths were analyzed. Then, a two-dimensional numerical tunneling model with general engineering parameters was established. The stress of grid points and Gauss points was calculated, and the stress changes of typical points were tracked. After that, the action zones of the stratum were classified, and the final ground settlements which consider action zones were calculated by turning the test results of strength into the corresponding action zone model. At last, a centrifuge test model was constructed, and the final surface settlement value was recorded. By contrasting test results with simulation results, the correctness of action zoning in silty clay stratum was verified. Source


Li S.-C.,Shandong University | Zhao Y.,Shandong University | Zhao Y.,Qingdao Metro Corporation | Xu B.-S.,Shandong University | And 4 more authors.
Yantu Lixue/Rock and Soil Mechanics | Year: 2012

The construction of subsea tunnel is high risky and water inrush is one of the main risk sources. If water inrush into the tunnel, it will have an important influence on the safety of construction as well as the control of operation cost after the subsea tunnel is completed. So making water inrush forecast is very important in the construction phase. Numerical analysis is the most popular method used in the prediction of water inrush at present, of which ascertaining the permeability coefficient is one key problem. Taking Qingdao Jiaozhouwan Subsea Tunnel as the project background, this paper deals with water inrush forecast during the subsea tunnel construction period by comprehensive usage of numerical computation, model test and local monitoring data analysis. Firstly, variation curves of the water inrush are got by monitoring the water inrush after tunnel excavation. Then numerical method is used to calculate the water inrush. During the process of calculating, parameters are adjusted constantly to fit the curve successfully. The permeability coefficient obtained is reasonable; it should be used in the numerical computation. Combined with the model geology, the relationship between the reasonable permeability coefficient and the permeability coefficient which is got from geological packer test in the early stage is obtained by comparison. Then model test is used to verify above conclusions. Finally, the conclusions can be used to other sections of subsea tunnel to make water inrush forecast. The result has significance for practice reference. Source


Zhang G.,University of Science and Technology Beijing | Zhang G.,Guangdong Hongda Blasting Engineering Co. | Du Z.,Qingdao Metro Corporation | Song J.,Guangdong Hongda Blasting Engineering Co. | And 3 more authors.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2012

Zhongshan Park Station of Qingdao subway line No.3, which is constructed by arch cover method, locates in soil-rock composite layer. The maximal excavation depth is about 27.24 m. Upper overburden is composed of quaternary and highly weathered granite, and the lower part is consisted of medium-slightly weathered granite and granite-porphyry. The thickness of partially highly weathered rock layer is large and the medium-slightly weathered rock surface is partly steep, which makes the contact surface unstable. To ensure the excavation work, the ground subsidence was monitored and analyzed at the station. Results indicate that the subsidence emerges before the tunnel working face reaches to about 20 m in front of monitoring sections when the arch cover method was adopted. With the decrease of distance between the tunnel working face and monitoring sections, the subsidence velocity continues to increase. Generally, the value of subsidence is 7-15 mm when the excavation face was going through the monitoring sections. The velocity of ground subsidence increases to the maximum until the working face passes through the monitoring sections for 5-10 m. After the working face passes through the monitoring section for more than 10 m, the subsidence velocity begins to fall. Most of observation points have the trend to be stable after the working face passes through the monitoring sections for about 20 m. Supporting should be exerted and closed as early as possible to make sure that the supporting can play a good role. In addition, there is a interrelationship between the left and right pilot tunnels. It is indicated that the appropriate distance between the left and right pilot tunnels should be 2.5 times of the diameter of pilot tunnel. According to the monitoring and analysis results, a series of control measures are put forward, which are proved to be feasible and effective by practice. Source

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