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Hu K.,China University of Mining and Technology | Zhou G.-Q.,China University of Mining and Technology | Jing L.-J.,Beijing SANY Heavy Machinery Ltd Company | Wang J.-Z.,China University of Mining and Technology | And 2 more authors.
Caikuang yu Anquan Gongcheng Xuebao/Journal of Mining and Safety Engineering | Year: 2010

In order to get the evolution law of the multi-circle freezing temperature field for thick top soil, we establishe a test system to study the temperature field of frozen wall in in thick top soil. In this system, the effect of pressure on frozen point of soil is considered. Based on similarity theory, the experiment on muti-circle freezing temperature field after loading were carried out by taking the ventilation shaft of Zhao Lou coal mine as the prototype. The results show that the closure time of freezing front of three chilled pipes is 50 days, the thickness and the average temperature of frozen wall are 11.2m and -22.8°C, respectively. And the fitting functions of the average temperature of frozen wall and the shaft-lining temperature changing with time are T1=-3×10-9τ3+2 ×10-5τ2-0.0358τ+2.932 and T2=-0.0207τ+10.32, respectively. When the temperature field of the characteristic surfaces is in quasi-steady stage, the thickness of frozen wall is almost stable, so the shaft-lining temperature and the average temperature of frozen wall satisfy the requirements of excavating shaft. When the temperature field of the characteristic surfaces is in steady stage, the cooling loads of chilled pipes are mainly used to maintain the temperature of inward and outward extending areas of frozen wall.

Sun D.,Shandong University of Technology | Zhu C.,Beijing SANY Heavy Machinery Ltd Company | Fan Z.,Shandong University of Technology | Li Y.,Shandong University of Technology
Beijing Hangkong Hangtian Daxue Xuebao/Journal of Beijing University of Aeronautics and Astronautics | Year: 2011

A self-adaptive filtering algorithm for scattered points was proposed. The node splitting algorithm and the clustering algorithm of R*-tree were improved and the spacial index structure of triangular mesh model was established based on the improved R*-tree; The local surface reference data was obtained according to data nodes' distributing of the spacial index structure; The filtering weight was computed by self-adjusting figure feature of 2-D Gauss distributing according to its local surface reference data; The weight value of local surface reference data to originality surface data was computed, and the coordinate of scattered points was computed according to this weight value; The self-adaptive filtering for scattered points was realized with the method of weighted mean. It proved that this algorithm can improve the efficiency of filtering and reduce the random error of the scattered points on the basis of the accurate reservation of surface characteristic.

Mao P.,Henan University of Science and Technology | Gao W.,Beijing SANY Heavy Machinery Ltd Company | Li S.,Henan University of Science and Technology | Hu C.,Luoyang tractor institute Co. | Zhang F.,Henan University of Science and Technology
Applied Mechanics and Materials | Year: 2012

Through an analysis of tractor traction balance, a mathematical model which can easily calculate the traction force and efficiency of tractors under different operating conditions was built up, this model offers a basis for tractor-implement matching. Bases on above analyses, the best efficiency rating value was deduced and the traction characteristic curve was also plotted, this study provides a theoretical basis for tractor traction characteristic research.

Tang X.,Tsinghua University | Deng K.,Tsinghua University | Deng K.,Beijing SANY Heavy Machinery Ltd Company | Wang L.,Tsinghua University | Chen X.,Tsinghua University
Automation in Construction | Year: 2012

The objective of this project is to investigate natural characteristics of thrust system. We found that with different arrangement and various extension of hydraulic cylinder, the stiffness of cylinder could be reduced. On one hand, based on the second form of Lagrange equation, we developed one vibration model for driving system. Through the eigenvalue theory of matrix analysis, we discovered the frequency line of the thrust system. On the other hand, by applying frequency lines to analyze the thrust systems of shield machine in engineering applications, features of natural frequencies in several systems with various arrangements have been discussed in detail. Case study shows that to prevent resonance, the avoiding band of the natural frequencies in even systems is much narrower than the one in uneven systems. The result provides a theoretical foundation and guideline for the design of thrust systems in shield tunneling machines. © 2011 Elsevier B.V. All rights reserved.

Zhao H.,Tsinghua University | Xu X.,Tsinghua University | Yu X.,Beijing SANY Heavy Machinery Ltd Company | Zhu X.,ESI Group Beijing Co.
Qinghua Daxue Xuebao/Journal of Tsinghua University | Year: 2014

The drill rod is one of the most important components of a rotary drilling rig and it is highly stressed. The pipe-bar welded joints are most likely to be damaged. The welding of pipe-bar joints is simulated using the SYSWELD software to calculate the residual welding stresses for comparison with measured residual welding stresses by X-ray diffraction. The calculated results are in good agreement with the measured data. The welding speed is then changed to study its effect on the residual welding stresses. The results show that the maximum tensile stress exists at the heat affected zone. With the increase of welding speed, the maximum tangential compressive stress increases, but the maximum tensile stress has no significant change.

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