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Temperature monitoring and control is of great significance to ensure concrete quality during the construction of dam concrete. In this study, a 3D thermal field restructuring method is developed for the complex evolution process of thermal field in dam concrete during construction, based on real-time temperature monitoring. The proposed method is related to the ordinary Kriging interpolation and the distributed optical fiber temperature sensing (DTS) technology. Based on the temperature monitoring of the Wudongde (WDD) super-high arch dam, the 3D thermal field can be acquired effectively and fast by the proposed restructuring method. The results indicate the temperature difference between the temperature measured by thermometers and the restructured temperature is within 1 °C. The evolution process of the restructured 3D thermal field for the WDD arch dam is in good agreement with the site situation. In addition, the uncertainty, cons and pros of the proposed method and the optimal layout of temperature sensors are further discussed. Although the proposed thermal field restructuring method has some limitations, it is believed to be a valuable tool for acquiring the 3D thermal field and thermal gradient of dam concrete.

Four CrAlN coatings with various Al content were prepared by arc ion plating technology under different target currents. The effect of the Al content on the microstructure, chemical compositions, element chemical bonding states and mechanical properties of the CrAlN coatings was analyzed. X-ray diffraction results show that the primary phase of the CrAlN coating is fcc-(Al, Cr)N when the Al content is about 44.02 at.%. However, when the Al content increases to about 53.34 at.%, hcp-AlN phase emerges in the coating. And the hcp-AlN phase becomes the main phase in the CrAlN coating with Al content of about 69.55 at.%. Cross-sectional images show that all the four coatings possess dense structures and the deposition rate of Al atom is higher than that of Cr atom. The hardness of the CrAlN coating with Al content about 44.02 at.% is the largest (3149.72 HV) due to the solid solution hardening effect of the Al element. When the hcp-AlN phase is generated in the CrAlN coating, the hardness declines. The tribological experiment shows that the wear resistance of the CrAlN coating decreases gradually with increasing Al content when sliding against 100Cr6 steel ball.

Four CrAlSiN coatings with different Al contents were prepared by varying Al sputtering power using a combined method of high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (DCMS). Microstructure, chemical compositions and mechanical properties of the four coatings were characterized by XRD, XPS, SEM, TEM, nano-indentation etc. Results showed that the four coatings possessed face-centered cubic (fcc) CrN phase with Al and part of Si dissolved in it. Another part of Si existed as amorphous phase in the coatings. All the four coatings had columnar structure and formed in epitaxy growth by template effect. With increasing Al sputtering power, the Al content increased from 11.4 to 17.6 at.% gradually, while the Cr content decreased a little. The hardness of the CrAlSiN coatings increased initially probably due to the refinement of the coating grain size, while it decreased afterwards mainly caused by the aggregation of small particles leading to rougher surface and defects formed in the coatings. The elastic modulus and adhesive strength possessed the same variation tendency as the hardness versus Al sputtering power. The CrAlSiN coating with Al sputtering power of about 0.8 kW had the highest hardness of about 26.7 GPa and adhesive strength of about 27.2 N.

A new type of AlTiN coating containing about 29.13 at.% Al,16.02 at.% Ti and 54.85 at.% N was prepared by arc ion plating technology. The coating is composed of singular fcc-(Al, Ti)N phase and has no hcp-AlN phase to be formed. Due to the high content of beneficial element Al, the hardness and effective elastic modulus of the coating are up to 33.9 and 486.1 GPa, respectively. The adhesion strength between the coating and substrate is about 39.7 N. Electrochemical test shows that the corrosion current density of the AlTiN coating is nearly one-sixth of the substrate, and the charge transfer resistance R ct of the AlTiN coating is much larger than that of the substrate, which means that the coating could act as a protective barrier between the substrate and corrosive electrolyte, enhancing the corrosion resistance.

The high-efficiency transverse joint simulation and analysis technique was developed based on the discontinuous deformation theory. This technique developed was used to realize the simulation of the overall construction and concreting process of the 300m super-high arch dam by the 3D finite element method, simulate the actual dam inside and transverse joint working behaviors throughout the process, analyze the temperature, stress and aperture change process in the inside and transverse joint face of the dam, discuss the opening and closing mechanism and crucial influencing factors of the transverse joint of super-high arch dam. Based on the feedback and analysis of field monitored data, the causes for the relatively small aperture in the foundation restraint zone of the arch dam were further analyzed, and the later aperture was predicted. The measures and proposals for effectively increasing transverse joint aperture and enhancing the groutability were further put forward, to provide important guarantee for ensuring the transverse grouting effect of the arch dam and the overall safety of the dam.

A Si doped Pt modified aluminide coating was prepared by electroplating and the chemical vapour deposition method. The microstructure and oxidation resistance of the coating were studied, with a single Pt modified aluminide coating as a reference. The results showed that the Si doped Pt modified aluminide coating consisted of singular &beta, (Ni, Pt)Al phase, and no PtAl2 phase was detected, which might be due to the fact that the addition of Si retarded the formation of PtAl2 phase in the outer layer. Si was dissolved in the &beta, (Ni, Pt)Al phase in the outer layer and might form silicide with refractory elements in the inter-diffusion zone. The Si doped Pt modified aluminide coating possesses a better oxidation resistance than the Pt modified aluminide coating since Si could promote the formation of &alpha, Al2O3 and inhibit the diffusion of the refractory elements, reducing the formation of detrimental volatile phase.

Two Co modified aluminide coatings with different Co contents were prepared by pack cementation process and above-the-pack process. The hot corrosion tests of the two coatings were performed in mixed salts of 75 wt.% Na2SO4 + 25 wt.% K2SO4 and 75 wt.% Na2SO4 + 25 wt.% NaCl at 700 °C, with a simple aluminide coating as the reference coating. X-Ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM) with energy dispersive X-ray spectrometer (EDS) were used to characterize the coatings and the corrosion scales. Results indicate that the addition of Co improves the hot corrosion resistance of the simple aluminide coating in the mixed sulfate salts, for the sulfide as well as its eutectic of cobalt are more stable, and possess higher melting points than those of nickel. While in the mixed salt containing chloride, the coating with medium Co content possesses the best corrosion resistance, primarily because the nitrides formed in the deposition process deteriorate the corrosion resistance of the coating with highest Co content.

A Cr-modified aluminide coating is prepared on a Ni-based superalloy using arc ion plating and subsequent pack cementation aluminizing. Hot corrosion behavior of the Cr-modified aluminide coating exposed to molten Na2SO4/K2SO4 (3:1) or Na2SO4/NaCl (3:1) salts at 900 °C in static air are evaluated as well as the aluminide coating. The results indicate that compared with the aluminide coating, the anti-corrosion properties of the Cr-modified aluminide coating in the both salts are improved, which should be attributed to the beneficial effect of the Cr in the coating. The corrosion mechanism of the Cr-modified aluminide coating, especially the role of Cr in the mixture salt corrosion, is discussed.

The isothermal and cyclic oxidation behaviour of two Co modified aluminide coatings together with the simple aluminide coating were performed at 1000 °C and 1100 °C. All the three coatings show a much lower oxidation rate compared with the bare alloy. Results also indicate the addition of Co to the aluminide coating decreases the oxidation resistance slightly. It can be ascribed to that Co is easier to be oxidized than Ni at high temperature, and the Cr(W) rich phases which could act as a diffusion barrier are less in the coating with higher Co content.

Two Co modified aluminide coatings with different Co contents were prepared by a combined method of pack cementation and chemical vapour deposition. The type-I hot corrosion tests of the two Co modified coatings together with the simple aluminide coating were carried out at 900 °C. Results indicate that the addition of cobalt could improve the corrosion resistance of the coatings in the sulphate salts, but exacerbate the degradation of the coatings when chloride salt gets involved. The formation mechanism of the Co modified aluminide coatings and the corrosion mechanism during the corrosion test have been discussed as well.

To take advantage of the synergistic effects of Pt and Zr, a kind of Zr-doped, Pt-modified aluminide coating has been prepared by a hybrid process, first electroplating a Pt layer and then co-depositing Zr and Al elements by an above-the-pack process. The microstructure and isothermal oxidation behavior of the coating has been studied, using a Pt-modified aluminide coating as a reference. Results showed that the Zr-doped, Pt-modified aluminide coating was primarily composed of β-(Ni,Pt)Al phase, with small amounts of PtAl2- and Zr-rich phases dispersed in it. The addition of Zr diminished voids on the coating surface since Zr could hinder the growth of β-NiAl grains. It also helped to increase the spalling resistance of the oxide scale and reduce the oxidation rate, which made the Zr-doped, Pt-modified aluminide coating possess better oxidation resistance than the reference Pt-modified aluminide coating at the temperature of 1100 °C.

This paper investigates the feasibility of a real-time tunnel location-based services (LBS) system to provide workers’ safety protection and various services in concrete dam site. In this study, received signal strength- (RSS-) based location using fingerprinting algorithm and artificial neural network (ANN) risk assessment is employed for position analysis. This tunnel LBS system achieves an online, real-time, intelligent tracking identification feature, and the on-site running system has many functions such as worker emergency call, track history, and location query. Based on ANN with a strong nonlinear mapping, and large-scale parallel processing capabilities, proposed LBS system is effective to evaluate the risk management on worker safety. The field implementation shows that the proposed location algorithm is reliable and accurate (3 to 5 meters) enough for providing real-time positioning service. The proposed LBS system is demonstrated and firstly applied to the second largest hydropower project in the world, to track workers on tunnel site and assure their safety. The results show that the system is simple and easily deployed.

This paper studies the feasibility of a real-time monitoring system to provide prompt analysis support of workers' behaviour on dam construction sites. The system makes use of wireless sensor tracking technology and a set of servers for the running of software, handling collected data, real-time site state visualization, and remote interaction communications. The low-level ZigBee-based tracking technology network hardware utilizing fingerprinting software technology was employed. The system was found to be able to cover a large field whilst retaining its simple and easily deployable features. The proposed system was successfully implemented on the Xiluodu arch dam construction site and ultimately helped overcome the original shortcomings in worker safety management and has advanced the means of administration and management's awareness and culture to new levels. The field tests also show that the received signal strength indicator (RSSI)-based localization algorithm implemented on ZigBee devices is reliable and is accurate enough at 3 to 5 meters. In conclusion, the system proved to be very useful for the management of field safety worker behaviour analyses in the case of such a high arch dam and also for similar hydraulic projects.

A preliminary study on removing THMs from chlorinated water by ozonation ( “O3” process) and granular activated carbon bed filtration and adsorption (AC process) was carried out. It was found that the chloroform content in chlorinated water was reduced to some extent by ozonation at low dosages, but then it increased steeply with time, and finally reached much higher than the original values.