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Yang T.,Beijing Institute of Technology | Xiong J.,Beijing Institute of Technology | Hao L.,China Construction Engineering Design Group Corporation Ltd
Huagong Xuebao/CIESC Journal | Year: 2015

Volatile organic compounds (VOCs) emitted from materials in indoor and vehicle environment is one of the main factors causing poor air quality and obviously affects people's comfort and health. The emission behaviors of VOC from materials are characterized by three key parameters, i.e., the initial emittable concentration (C0), the diffusion coefficient (Dm) and the partition coefficient (K). Determination of the above key parameters is the foundation of researches for emission laws of VOC from materials as well as prediction for human exposure and health risks. Based on the most widely used VOC emission process in ventilated chamber at present, this paper proposes a novel method to simultaneously determine C0 and Dm. By assuming an initial value for K and then performing the linear curving fitting for the logarithm of chamber concentration, the key parameters C0 and Dm can be obtained from the slope and intercept of the fitting results. As is shown in sensitivity analysis, the variety of K has little effect on the determination of C0 and Dm. By the virtue of the treatment for experimental data of ventilated chamber tests in literature, it is demonstrated that the proposed method has a relatively high accuracy. ©, 2015, Chemical Industry Press. All right reserved.


Xie L.-J.,Shanxi Institute of Coal CAS Chemistry | Xie L.-J.,University of Chinese Academy of Sciences | Wu J.-F.,China Construction Engineering Design Group Corporation Ltd | Chen C.-M.,Shanxi Institute of Coal CAS Chemistry | And 9 more authors.
Journal of Power Sources | Year: 2013

Co3O4-reduced graphene oxide (rGO) nanocomposites are prepared by co-precipitation of Co(OH)2 with graphite oxide (GO) to form a Co(OH)2-GO precursor, followed by thermal treatment. It is found that the ratio between Co3O4 and rGO has a significant effect on their electrochemical activities. The specific capacitance of 636 F g-1 is achieved when the mass ratio of Co3O 4 to rGO is equal to 80.3:19.7. A novel asymmetric supercapacitor is further fabricated with the Co3O4-rGO nanocomposite as the anode and activated carbon as the cathode in 6 M aqueous KOH solution as electrolyte. The assembled asymmetric supercapacitor can cycle reversibly in a voltage of 0-1.5 V and exhibits a high energy density of 35.7 Wh kg-1 at power density of 225 W kg-1. Moreover, the asymmetric supercapacitor shows an excellent cycling stability with capacitance retention of 95% after 1000 cycles at a current density of 0.625 A g-1. © 2013 Elsevier B.V. All rights reserved.


Guo X.,Beijing Jiaotong University | Zhu K.,Beijing Jiaotong University | Zhang X.,China Construction Engineering Design Group Corporation Ltd | Zhang D.,Beijing Jiaotong University | And 2 more authors.
Tiedao Xuebao/Journal of the China Railway Society | Year: 2016

Based on the DOT (Double-O-Tube) shield tunnel projects such as Shanghai M8 line, the model test study of the interaction between the lining structure and soft soil layer of the DOT shield tunnel was carried out. Through the series of orthogonal experiments, the parameters effect of the interaction between the soft soil and the DOT shield lining was investigated to observe the structural internal force response of the DOT shield lining under the action of the soft soil layer. By comparison, it is found that the vertical column in the interval between Ring1 and Ring2 (1.2~2.4 m) can ensure the control of the deformation of the lining to stay in the 3 mm range of the specifications required, and the test results were consistent with the actual deformation results of the whole ring layout of the M8 lining. The reduction coefficient of internal force transmission was from 0.61 to 0.97. Cross-scale comparative analysis of stratum sedimentation and particle migration law was given by using particle image velocimetry PIV2C software and test camera system to compare the field measured data. The results showed that the influence law of the stratum settlement curve from the surface to the lining of the top performance was shown as the “U-V-W type” change. With the collapse area ratio of 0.85, the technique of PIV can better reveal DOT shield soft soil saddle groove and transient migration law of forming an arch collapse in the DOT tunnel construction process. © 2016, Editorial Office of Journal of the China Railway Society. All right reserved.


Guo X.,Beijing Jiaotong University | Zhang X.,China Construction Engineering Design Group Corporation Ltd | Wang M.,Beijing Jiaotong University
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2015

Sinusoidal curved lateral resistance method (SCLRM) is the theoretical correction for triangular method. Considering the nonlinear characteristics of soft, underwater soft plastic and composite strata that the large diameter tunnel passing through, the lateral resistance was corrected in SCLRM. The theoretical formulas of SCLRM were derived and the example was shown. Based on the free-form deformation method (FFD), the internal force distribution for the lining structure were calculated using triangle method and SCLRM. The scope and restriction of the application of theory were expanded. The applicability of each lateral resistance method in actual complex formations was discussed. Comparing the measurement value with theoretical results for Nanjing subway line one, it is indicated that the internal force calculation of single round integral type shield tunnel by SCLRM having a definite procession and a small error range which are suitable for this engineering example design. Application of this example provided a theoretical reference of internal force maximum value for designing single round shield tunnel passing through the composite strata. It seems that SCLRM has the certain practicality for similar project design. ©, 2015, Academia Sinica. All right reserved.


Guo X.,Beijing Jiaotong University | Zhang D.,Beijing Jiaotong University | Zhao C.,Beijing Jiaotong University | Zhang X.,China Construction Engineering Design Group Corporation Ltd | And 2 more authors.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2016

The damage theory was introduced based on the thermodynamic potential function and a new damage constitutive theory for hyperplastic structure of deep rock was established. The new internal variable pairs: strain (including damage accumulate strain and structural rearranged strain) and the corresponding generalized stress, the temperature and entropy were defined and four kinds of thermal energy function: Internal energy, Helmholtz free energy, enthalpy and Gibbs free energy were used to describe the hyperplastic constitutive theory of rock structure. The rock constitutive theory obtained satisfies the laws of thermodynamics. The framework has a strict physical meaning and can reasonably consider the structural characteristics of rock. The links between the different energy functions were established by using the Legendre transformations. Dissipative functions were introduced through the kinematic internal parameters and their conjugate variables (generalized stresses). The plastic dissipation function or yielding function of deep rock was given for the various conditions of pressure and temperature. It can reflect the damage character and structural rearrangement of the volume changes at the same time, which could be related through a degenerate case of Legendre transformation. The incremental stress-strain relation and new application examples were constructed for the deep rock structure. The criterion of application was provided. © 2016, Science Press. All right reserved.


Zhang J.-W.,Beijing University of Technology | Yang X.-M.,China Construction Engineering Design Group Corporation Ltd | Cao W.-L.,Beijing University of Technology | Hu J.-M.,Beijing University of Technology
Gongcheng Lixue/Engineering Mechanics | Year: 2016

To replace the traditional clay-brick structure and adapt to the requirements for the development of energy-saving buildings, the reinforcement concrete (RC) shear wall structure with a single layer of web reinforcement and inclined steel bars was proposed. Compared with conventional RC shear wall structures with double layers of web reinforcement, it has the advantages of smaller wall thickness, simpler construction details and lower cost. The inclined steel bars can prevent base sliding so that the shear wall has higher anti-shearing and energy dissipation capacity. Cyclic loading tests on four low-rise RC shear walls with rectangle cross section were carried out. The inclined steel bars arrangement and axial force ratio were taken as the major test variables. Based on the experimental research, the failure characteristics, hysteresis properties, load-carrying capacity, ductility, stiffness and energy dissipation of each specimen were analyzed. The seismic performance of RC shear walls with inclined steel bars was compared with that of RC shear walls without the inclined steel bars. Calculative formulas for the load-carrying capacity of low-rise RC shear walls with single web reinforcement and inclined steel bars were also established. The research results indicate that the seismic performance of low-rise RC shear walls with inclined steel bars is better than that of shear walls without the inclined steel bars. So it is able to better satisfy the requirements of seismic design for multistory residential buildings. © 2016, Engineering Mechanics Press. All right reserved.


Guo X.,Beijing Jiaotong University | Zhang X.,China Construction Engineering Design Group Corporation Ltd | Wang M.,Beijing Jiaotong University
Mathematical Problems in Engineering | Year: 2016

The thermomechanical transport approach includes the process of diffusing or the condition of being diffused, absorption/desorption, swell/shrink, equilibrium/nonequilibrium, and thermomechanical transport of contaminant in three phases of polluted mining soil which are discussed. The thermomechanical transport model of the contaminants transport in polluted soil is established, and its basic equations are given. Based on that, the distribution regularities of the contaminant seepage in water-soil system are discussed in detail and the sensitivities of parameters are analyzed. The study shows that the parameter has important influence on the contamination distribution and transportation in polluted soil-water system. The influence degree is also related to the action of seepage force directly. © 2016 Xuan Guo et al.


Yang X.,China Construction Engineering Design Group Corporation Ltd | Hu J.,Beijing University of Technology | Zhang J.,Beijing University of Technology | Xing M.,China Construction Engineering Design Group Corporation Ltd | Cao W.,Beijing University of Technology
World Information on Earthquake Engineering | Year: 2016

For investigating the seismic performance of the Z-section shear wall with single row of steel bars and inclined reinforcements along flange direction, the low-cyclic loading tests on two Z-section shear walls were carried out. One wall has general bidirectional single row of steel bars and another wall has bidirectional single row of steel bars and inclined reinforcements. Based on the experimental research, load-carrying capacity, stiffness, ductility, hysteresis characteristic, energy dissipation capacity and failure characteristics were analyzed comparatively and the calculating model of the ultimate load-bearing capacity was established. Results show that the seismic performance of Z-section shear wall with inclined reinforcements along flange direction is better than that of general shear wall without inclined reinforcements. So it is able to meet better the requirements of seismic design of multi-story residential structure. © 2016, Science Press. All right reserved.


Guo X.,Beijing Jiaotong University | Zhang H.,Beijing Jiaotong University | Meng J.,Beijing Jiaotong University | Zhang X.,China Construction Engineering Design Group Corporation Ltd | And 2 more authors.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2016

36 sets of orthogonal model tests on the ultimate bearing capacity of the pre-support system of tunnels with pipe roof in soft surrounding rock were carried out. The pre-supporting system with pipe roof was found to effectively prevent the collapse when cross-cover ratio H/D=1. The 120° arrangement of pipe shed advanced support reduced 59.5% (H/D=2) and 64.8% (H/D=3) of the maximum surface settlement. The 150° arranged pipe roof reduced 63.2% (H/D=2) and 76.8% (H/D=3) surface maximum settlement. The recommended range of width parameter K of Peck formula was given by fitting the experimental data. K increased with the density of pipe roof, and increased about 0.13 in 120° pipe arrangement, about 0.19 in 150° pipe arrangement. The limit bearing capacity of supported surrounding rocks was approximately doubled in the ultimate load tests, and the destruction form was changed from the dome collapse into the sidewall squeezing in the process of the tunneling and loading. © 2016, Science Press. All right reserved.


Guo X.,Beijing Jiaotong University | Liu B.,Beijing Jiaotong University | Zhang X.,China Construction Engineering Design Group Corporation Ltd | Zhang D.,Beijing Jiaotong University | And 2 more authors.
Tiedao Xuebao/Journal of the China Railway Society | Year: 2016

In response to typical engineering characteristics of existing Beijing subway traversing the loose sand and gravel, large particles of coarse sand, silt interbed, and complex uneven hardness sections, an excavation failure model experiment was carried out for shallow buried tunnel lining with tunnel overburden layer of 1-3 times of the tunnel diameter. The mechanical model of the dynamic collapse umbrella arch structure with the interaction of lining-soil structure was established, to observe the dynamic slip zone pressure arch characteristics surrounding the lining, and to analyze the pressure distribution partition of the sand gravel composite formation for metro lining earth. This model can define the local soil arching effect and area reduction characteristics in the vicinity of the sliding area, including the interaction of lining-soil structure formation of quasi arch, progressive collapse sink, failure experiment instant collapse wear failure process. The results of FLAC3D simulation and model failure experiment were coincident. Through the actually monitored results of soil pressure value of the arch crown of the Tiantandongmen subway station, the mechanical model was preliminarily verified, which can provide reference for the load values of process soil pressure of similar projects. © 2016, Science Press. All right reserved.

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