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Changsha, China

Du Y.-L.,Central South University | Du Y.-L.,Survey & Design Institute | Huang M.-H.,Donghua University | Zheng Y.,Donghua University
Journal of Donghua University (English Edition) | Year: 2015

Effect of sludge retention time (SRT) on the removal of potential and polysaccharides in an anaerobic/anoxic/aerobic (AAO) process was investigated. The Lowry method and anthrone method were used to detect proteins and polysaccharides. Total removal efficiency of proteins at SRT of 10 to 25 d in the AAO system was higher than 90%. Polysaccharides removal efficiencies were above 80% when SRT was increased from 15 to 25 d, whereas only 81% of polysaccharides was removed at SRT of 10 d. The biodegradation part of proteins and polysaccharides increased from 87.40% to 93% and from 74.22% to 86.94% with increasing SRTs. The ratios of polysaccharides and proteins in extracellular polymer substances (EPSs) were around 1.5-3 in different SRTs. As SRT increasing, polysaccharides and proteins discharged with residual sludge decreased gradually. The amount of EPSs decreased with increasing SRTs. Copyright © 2015 by Editorial Board of Journal of Donghua University, Shanghai China. Source

He X.,Survey & Design Institute | Zhu Z.,Central South University | Peng L.,Survey & Design Institute | Dai G.,Survey & Design Institute
Acta Seismologica Sinica | Year: 2015

In this paper, the expressions of phase velocities for homogeneous and inhomogeneous P, SV, SH plane waves are derived from Christoffel equation. Phase attenuation coefficient and group attenuation coefficient for inhomogeneous and homogeneous plane wave are derived by the method used for extreme anisotropic medium. The relation between phase attenuation coefficient, group attenuation coefficient and azimuth of cracks is studied through numerical calculation. It is concluded that fracture can be indicative by SH wave phase velocity and attenuation coefficient in a homogeneous medium. SH wave attenuation coefficient increases with the increase of inhomogeneous angle, and the angle between its axis of symmetry and the symmetry axis of media also increases correspondingly in inhomogeneous medium; attenuation of seismic wave amplitude is more sensitive to variation of the rock's physical properties than the variation of wave velocity, and it carries more information about petrophysical properties. Therefore, it can be used to probe the azimuth of cracks, crack density, water content and to forecast and prevent from geological disasters in underground engineering. © 2015, Acta Seismologica Sinica Press. All right reserved. Source

Liu Y.-S.,Beijing Jiaotong University | Liu Y.-S.,Survey & Design Institute | Peng L.,Survey & Design Institute | Wang M.-S.,Beijing Jiaotong University | And 2 more authors.
Zhongguo Gonglu Xuebao/China Journal of Highway and Transport | Year: 2015

With the complexity of forming tunnel loosing rock zone, the fracture mechanism and rupture range of fractured rock-mass tunnel under blasting effect were investigated with fracture mechanics theory and test methods (such as sonic method and multi-point displacement meter method), taking Xiang'an Subsea Tunnel in Xiamen as the research object. Furthermore, the influence of blasting on the forming of tunnel loosing rock zone was quantitatively analyzed. The results show that with the effect of explosive stress wave, fractured rock-mass emerges three failure modes under different azimuth angles, including tensile-shear failure, shear failure and tensile failure. The maximal blast-induced fracture rock-mass zone can be confirmed according to cracks' arrest condition and fracture criterion under the condition of tensile-shear stress. The proportion of blast-induced fractured zone on the total loosing rock zone of grade II rock mass is about 45% to 55%. The theoretical calculation result basically matches the result of field test, which provides a reliable basis for the analysis of forming tunnel loosing rock zone. ©, 2015, Xi'an Highway University. All right reserved. Source

Liu Y.,Beijing Jiaotong University | Liu Y.,Survey & Design Institute | Peng J.,Survey & Design Institute | Wang M.,Beijing Jiaotong University | And 2 more authors.
Tumu Gongcheng Xuebao/China Civil Engineering Journal | Year: 2015

Taking Xiamen Xiangan subsea tunnel as the research object, based on the measured results of blasting vibration and Numerical simulation analysis by ANSYS/LS-DYNA, attenuation law of vibration in the zone of tunnel vault and pre-and-post of tunnel face were researched. In the field test, law of vibration in the radial direction and axial direction of the tunnel were tested system. It is proved that the vibration field formed with drill and blast excavation followed the typical vibration rule of single linear charge that vibration in the radial direction was strongest, which in the back of tunnel face takes second place, and in the front of the tunnel face was at least. And Blasting damage zone was about 0.5-1.5m in the footage of 2~4m in grade II surrounding rock-mass, blasting damage zone was 1~2m in the footage of 1.5~3m in grade V surrounding rock-mass. Each cycle footage was suggested about 3~4m and 1.5~2.0m in grade II and grade V surrounding rock-mass. ©, 2015, Editorial Office of China Civil Engineering Journal. All right reserved. Source

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