Jiang C.,Hohai University |
Huang S.,Hohai University |
Zhu Y.,Hohai University |
Lin Y.,Design and Research Institute Co. |
Chen D.,Hohai University
Advances in Materials Science and Engineering | Year: 2016
The fresh, mechanical, and durability properties of the polypropylene fiber-reinforced mortar (PP FRM) and the basalt fiber-reinforced mortar (BFRM) with various fiber contents were tested in this paper. The test results show that the presence of polypropylene (PP) fiber and basalt fiber (BF) in the mortar reduces the initial slump flow and increases the slump flow loss rate. The bond strength and flexural strength of fiber-reinforced mortar (FRM) are improved, whereas no obvious improvement on the compressive strength has been observed. Compared with the control mortar, the bond strength of PP FRM and BFRM reinforced with 0.6 kg/m3, 1.6 kg/m3, and 2.6 kg/m3 fiber increases by 16.60%-28.80% and 10.60%-21.40%, respectively. Furthermore, FRM shows lower drying shrinkage, superior abrasion resistance, water impermeability, and freeze-thaw resistance compared with the control mortar. The abrasion resistance strength of PP FRM and BFRM is 77.30% and 38.65% more than the control mortar with 2.6 kg/m3 fiber content. Therefore, PP FRM and BFRM are suitable to be utilized as repair materials, especially in repairing hydraulic structures surfaces with excellent bond strength and abrasion resistance. © 2016 Chaohua Jiang et al.
Li X.-G.,Beijing Jiaotong University |
Sun H.-C.,China Railway Electrification Bureau Group Co. |
Zhang J.-Q.,Design and Research Institute Co.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2011
The PLC hydraulic synchronization control system is used to control the deformation of the existing metro structure during the construction of Dongzhimen Station of Airport Line under the reentry line of Dongzhimen Station of Line 13 of Beijing Metro. Combined with the construction sequences of the drift and pile method, the idea of zoning, phasing, grouping, and staging is adopted to design the overall jacking scheme. The zoning idea refers to the respective calculation of the jacking force according to different structure types of the existing line; the phasing idea means that three phases are divided based on typical construction cases and the control scheme at each phase is respectively made; the grouping idea refers to driving the jacks into different groups and grouping control; the staging idea means the implementation of staged control of the jack force of each group and slow increase of the jacking force to reach the design values. Based on the measured deformations of the existing line, the 3rd phase jacking scheme is executed six times. Practice shows that the PLC hydraulic synchronization control jacking technology may slow the settlement speed and reduce the settlement amount of the existing structures to ensure the safe operation of the existing line, which is an active defense method.
He X.-L.,China Earthquake Administration |
She T.-L.,China Earthquake Administration |
Xu B.,Design and Research Institute Co. |
Li J.,Design and Research Institute Co. |
And 2 more authors.
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2016
The bolt looseness is a usual and serious disease of wind turbine towers. Based on a large number of measurements, the conclusion was obtained that the first-order phase difference characteristic of a wind turbine tower is sensitive to the loosen bolts of its flanges. Six wind turbine towers with loosen bolts were measured and analyzed for their vibration parameters. After the bolts looseness, the first-order natural frequency keeps unchanged and the variations in its damping ratio and its first-order vibration mode are also not obvious. At the same time, there appears an obvious sudden change in the phase difference of the upper and lower flanges despite the bolts looseness ratio reaches 6%. But the phase difference of the upper and lower flanges doesn't show the sudden change once again after their re-fastening. The measurements show that the first-order phase difference characteristic of a wind turbine tower is more affected by its loosen bolts of flanges than other vibration characteristics. As a result, the first-order phase difference characteristic can express the bolts looseness of flanges more accurately. The serious bolts looseness can be detected by the sudden increasing of the absolute values of the phase difference of upper and lower flanges. Based on the field measurements of six wind turbine towers under different working conditions, the method presented is more reliable and more effective to detect the loosen bolts of wind turbine towers rapidly. © 2016, Editorial Office of Journal of Vibration and Shock. All right reserved.
Yan M.,Shenyang University of Technology |
Zheng P.,Shenyang University of Technology |
Li Y.,Design and Research Institute CO. |
Lin J.,Design and Research Institute CO. |
Gao X.,Design and Research Institute CO.
Advanced Science Letters | Year: 2011
The traditional creep-thermal fatigue analysis based on linear or nonlinear damage accumulation assumption, calculates the creep and thermal fatigue respectively. This method can not reflect the mechanism of the interaction, so it is difficult to get a precise result. The mechanical behavior of the creep and thermal fatigue interaction is studied considering the bilinear kinematic hardening and creep characteristics of the material. The larger the compressive inelastic strain is during heating and insulating, the larger the tensile stress and strain will be at the end of cooling. Therefore, the material with higher compressive yield limit and lower creep rate should be preferred in designing the components subjected to creep-thermal fatigue damage. Creep affects the stress amplitude and the mean stress of the cycle, and makes them stable after a few cycles. Thus, the creep-thermal fatigue damage can be equaled to thermo-mechanical fatigue damage, which simplifies the life prediction and failure test. © 2011 American Scientific Publishers. All rights reserved.
Ying H.,Zhejiang University |
Nie W.,Design and Research Institute Co. |
Huang D.,Third Railway Survey and Design Institute Group Corporation
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2014
Groundwater level in coastal region fluctuates periodically due to wave or tides. The response of the pore pressures of the ground near the retaining wall is vital for pit excavation. In this study, a single layer ground with finite thickness around the pit to be excavated was considered to be isotropic and homogeneous. The fluctuating water level at the boundary was assumed to be a sinusoidal function. The seepage area around the pit was divided into three zones. Assuming the total stresses of soil keeping constant, the two-dimensional consolidation equations were decoupled. A semi-analytical solution of pore pressure of the ground around the pit with gravity retaining wall in response to the groundwater level fluctuation was derived with Laplace and Fourier transforms. The comparisons with the results from finite element software PLAXIS verified the proposed method. An example was presented to investigate the pore pressure response around the pit and its influence on the stability of the retaining wall via the above semi-analytical solution. The results show that the amplitude of pore pressure attenuated along the seepage path from the back to the front of the retaining wall, while the phase lag increased. The stability of the retaining wall fluctuates and has phase lags too as the groundwater level fluctuating.
Zuo Z.,Design and Research Institute Co. |
Chen Y.,Design and Research Institute Co. |
Cheng B.,Design and Research Institute Co. |
Hu W.,Design and Research Institute Co. |
And 3 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2016
Macrobenthic communities play vital roles in the processes of material circulation and energy flow of constructed wetland ecosystems. These roles are also critical for sustaining the structural stability and operational efficiency of such systems. Hydrophytes are one of the most obvious biological components of constructed wetland ecosystems. However, little information is available on the differences in the macrobenthic communities that occupy different hydrophyte monoculture configurations. In the present study, a series of quarterly investigations on macrobenthic communities was carried out from August 2013 to May 2014 in surface flow wetland (SFW) monocultures of Phragmites communis, Zizania latifolia, or Typha angustifolia, Yanlong Lake, in China. The aim of this study was to explore the ecological characteristics of macrobenthic communities in SFWs of different hydrophytes and their relationships with environmental factors. Relative importance analysis, diversity index (Shannon, Pielou, Margalef) analysis, and correlation analysis were used in this study. Fourteen macrobenthic species were found (i.e., mollusk: 7, arthropod: 4, and annelida: 3). Parafossarulus striatulus, Limnodrilus hoffmeisteri, Alocinma longicornis, and Tendipes sp. were the predominant species in the study areas. The population density and biomass of these species varied according to the major hydrophyte in each SFW. The annual average density of macrobenthos in the SFWs of P. communis, Z. latifolia, and T. angustifoliawas 285 ind/m2, 330 ind/m2, and 266 ind/m2, respectively, and the annual average biomass was 25.6 g/m2, 104.0 g/m2, and 32.3 g/m2, respectively. The highest number of species and greatest evenness among species of the macrobenthic community were found in the SFWs of Z. latifolia. These were significantly higher than those found in the SFWs of P. communis and T. angustifolia. However, there were no significant differences in the macrobenthic diversity between the SFWs of P. communis and T. angustifolia. In the SFWs of Z. latifolia, the macrobenthic biomass was significantly and positively correlated to the density of mollusks (P< 0.01), and the total density was significantly and negatively correlated to water depth (P< 0.05); the density of annelida was significantly and positively correlated to both STN (P< 0.01) and SOM (P< 0.05). This study is helpful for improving our understanding of the ecological characteristics of the macrobenthic communities in constructed wetlands and provides new insights into SFW design, management, and long-term operation. © 2016, Ecological Society of China. All rights reserved.
Jiang D.-Y.,Dalian Maritime University |
Feng Z.-Q.,Dalian Maritime University |
Zhang J.-D.,Dalian Maritime University |
Wu P.-L.,Design and Research Institute Co.
Dalian Haishi Daxue Xuebao/Journal of Dalian Maritime University | Year: 2014
With the fuel common rail system of RT-flex diesel engine as the simulation object, the working principle and structural features were studied. The mathematical models of high pressure fuel oil pump, intermediate fuel accumulator, fuel rail ICU piston as well as injector were established. Simulink results show that the mathematical models are proper. The visual simulation system of the common fuel rail system in RT-flex diesel was developed by VS2012. The visual simulation system can display the working principle and running of the common fuel rail system, which is useful in developing marine engine simulator and training candidates.
Wu S.-F.,Design and Research Institute Co.
Bridge Construction | Year: 2014
The Gusaoshu Road Overpass Spanning Railways is a prestressed concrete continuous box girder bridge of variable section with span arrangement (70+116+70) m and deck width 32 m. Considering that the overpass is required to span 11 railway lines and to ensure the safe operation of the railways during the construction and minimize the interference of the construction to the railways, it is determined in the design that the overpass should be constructed by the rotation erection method (with the rotating weight being 17 300 t and the maximum rotating angle being 106°) and the closure segment of the central span should be shifted 9.25 m from the right center of the central span towards the direction of the main mileage. The main girder of the overpass is of the cross section of five cells and single box. The main piers are the m-shape piers to be supported on the bored pile foundations. The rotation system is mainly comprised of the bearing system, pushing and hauling system and the balancing system. The dimensions of the spherical hinges are respectively 4 m for the Pier Z63 and 3.9 m for the Pier Z64. The software MIDAS Civil 2011 and MIDAS FEA are used to calculate the static forces of the main girder, m-shape main piers, rotation system, cross beams and deck slabs. The results of the calculation show that the various indices of the overpass can satisfy the relevant requirements in the codes.
Liu W.,Design and Research Institute Co. |
Zhao F.-Y.,Design and Research Institute Co. |
Yang W.-H.,Design and Research Institute Co. |
Chen X.-F.,Design and Research Institute Co.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2013
As for the planning Caohai section of Anning-Songming line which adopts shield tunnel project, the peaty soil is the main engineering geological problem. The sedimentary environments, distribution, characteristics and general physical and mechanical indices of the peaty soil are studied, and the special in dices of the second layer of peaty soil are analyzed. The second layer of peaty soil with large compressibility, low degree of consolidation, high shear strength and unconfined compressive strength, low sensitivity, low dynamic strength, large dynamic shear modulus ratio and small damping ratio has great influence on the shield tunnel project. Large settlement and differential settlement are easily caused, and the seismic performance is poor. Accordingly, the test schemes and measures should fully consider the particularity of the peaty soil.
Jin G.-D.,Design and Research Institute Co.
Journal of Railway Engineering Society | Year: 2013
Research purposes: In urban area, the design of tunnel usually needs to consider certain interchange relations with other tunnels (or other structures), such as overpass, underpass, etc. These adjacent and interchange relations are the difficult and important points for designing tunnel, so they become the control factors for tunnel design and construction. New Zhongliangshan Tunnel of Chengdu-Chongqing Passenger Line has different interchange relations with existing tunnels and it is highly influenced by the existing tunnels and interchange relations. Different adjacent tunnel design requires quite different construction method, which means how to guarantee the construction safety and operation security of the existing tunnels are the research focuses in this paper. Research conclusions: According to the research, it can be drawn: (1) When the new tunnel under wear both tunnel, can through the adoption of forepole controlled blasting and ensure the safety of the tunnel construction safety and existing lines. (2) New super small clear distance tunnel across both the tunnel, in the case of clearance limit llowed, can through the tunnel reinforcement and grouting behind the lining, by improving the existing tunnel structure to ensure the safety of the existing tunnel. (3) For the proposed subway down through the tunnel under construction, the proposed subway can be applied through the tunnel under construction for auxiliary measures can be applied in advance for interchange effect, reduce the influence of the planned tunnel on existing tunnel, ensure safety. (4) For two proposed tunnel, when the first a lower tunnel construction, should be considered in the late on across the tunnel construction load and operating load, the influence of the primary support and secondary lining consider appropriate to strengthen. (5) When across the tunnel on the early construction, priority and tunnel construction during this period, reduce the wear on the tunnel construction on across the influence of the tunnel. (6) This research result can be applied in tunnel near the design of the tunnel section.