Dynamic Response of CFRP Reinforced Steel Beams Subjected to Impact Action Based on FBG Sensing Technology.

The in-situ health condition of carbon fiber reinforced polymer (CFRP) reinforced structures has become an important topic, which can reflect the structural performance of the retrofitted structures and judge the design theory. An optical fiber-based structural health monitoring technique is thus suggested. To check the effectiveness of the proposed method, experimental testing on smart CFRP reinforced steel beams under impact action has been performed, and the dynamic response of the structure has been measured by the packaged FBG sensors attached to the surface of the beam and the FBG sensors inserted in the CFRP plates. Time and frequency domain analysis has been conducted to check the structural feature of the structures and the performance of the installed sensors. Results indicate that the packaged Fiber Bragg Grating (FBG) sensors show better sensing performance than the bare FBG sensors in perceiving the impact response of the beam. The sensors embedded in the CFRP plate show good measurement accuracy in sensing the external excitation and can replace the surface-attached FBG sensors. The dynamic performance of the reinforced structures subjected to the impact action can be straightforwardly read from the signals of FBG sensors. The larger impact energies bring about stronger impact signals.

[Feasibility of sewage sludge used as filling material in permeable reactive barrier].

Permeable reactive barriers (PRB) have been used widely as an alternative technique to treatment of acid mine drainage (AMD). Selection of the appropriate filling materials is the most important procedure to application of this treatment. Batch adsorption tests and bacteria culture batch tests were conducted to assess the possibility of sewage sludge served as filling material for PRB. Results from batch adsorption tests showed that the maximum adsorption capacities of the sewage sludge were 13.62 mg x g(-1) (Zn2+) and 15.60 mg x g(-1) (Cd2+). Bacteria culture batch tests indicated that SO4(2-) concentrations in reactors decreased from initial concentrations of 700 mg x L(-1) to below 300 mg x L(-1). Sulfate removal efficiency ranged from 60% to 70%. Fe and heavy metals, including Zn and Cd, were removed completely in two reactors. This study suggested that sewage sludge is a suitable filling material for PRB.

[Oxidation buffer capacity of sewage sludge barrier for immobilization of heavy metals].

Benefit from the microbial activities especially the anaerobic sulfate reduction processes, sewage sludge could be used as a barrier to immobilize the heavy metals leached from tailings. With respect to the redox reaction between sewage sludge and acid mine drainage (AMD), oxidation titration test was carried out to study the effect of oxidation buffer capacity (OBC) of sewage sludge on the immobilization of heavy metals. Test results showed that OBC of sludge suspensions was decreased slightly with the solid-liquid ratio of the suspensions, but increased with the anaerobic incubation time, and that more than 50% of OBC was contributed by the sludge existed in strongly-reduction conditions (Eh < or = - 150 mV). During oxidation titration test, Zn was released obviously when Eh > or = - 150 mV, while Cu and Pb released obviously when Eh > or = 150 mV. According to the test results, a mathematical model was established to predict the OBC consumption of the sludge barrier under AMD penetrating conditions. The simulation results showed that a sludge barrier with 2m thickness, even undergone 38 787-years oxidation by AMD under 10m water head, keep in a strongly-reduced condition and, therefore, promote an immobilization of heavy metals from AMD in the barrier.

[Acid buffer capacity of sewage sludge barrier for immobilization of heavy metals].

Employing the anaerobic activities of microorganisms, sewage sludge can be used as a barrier to immobilize the heavy metals leached from tailings. Due to the interactions between sewage sludge barrier and acid mine drainage (AMD), it is possible that the heavy metals that have been immobilized previously might be released out. The acid buffering capacity (ABC) of sewage sludge suspensions with various anaerobic incubation time and the effect of ABC on the mobility of heavy metals were investigated by acid titration tests. Test results showed that ABC of sewage sludge suspensions was increased with the solid-liquid ratio of the suspensions and the anaerobic incubation time, and that carbonate and organics play an important role in acid buffer of sewage sludge suspensions. During the acid titration test, Zn, Pb and Cu were released out obviously following the order of Zn > Cu > Pb as pH was decreased less than 6.2. A mathematical model was established to predict the ABC consumption of the sewage sludge barrier under AMD penetration condition. The simulation results showed that a sewage sludge barrier with 2.0 m thickness, even undergoing 666-years acidification by AMD under 10.0 m water head, can maintain a condition of pH > or = 6.2 and, therefore, keep immobilize the heavy metals of AMD in the barrier.