Numerical simulation of blasting effect with divided charge structure

This paper numerically simulates the stress development and generates a three-dimensional model of the medium-length hole blasting in infinite rock mass for continuous charge and divided charge in blasting by us- ing the large-scale nonlinear dynamic analysis software LS-DYNA and the elastic-plastic model ＊MAT_PLAS- TIC_KINEMATIC and JWO-EOS. The differences of the decreasing rate in Von Mises effective stress of blas- ting, element effective stress peak of free surface, bore wall stress and acceleration are investigated. It is shown that divided charge could greatly improve the blasting effect by engineering blasting practice.     

Blasting technologies of vibration damping in subway tunnel passing under upper buildings closely

Reducing the blasting vibration is important for blasting excavation in subway tunnel construction. Taking the 3rd bid section of Line 3 of Qingdao subway project as an example, the distance between tunnel vault and ground is 5 - 8 m. In order to insure the safety of the upper buildings, technologies of parallel cut with large diameter empty hole, one-time initiation and delay by parts, and multiple shallow holes were adop- ted in the project. The results showed that the maximum value of vertical vibration was limited in the criterion allowance, and the upper buildings were not damaged. Besides, problems were solved that the number of nonel detonator was difficult to meet the requirements of excavating a large cross-section tunnel by blasting, multiple cross-section could＇ t be initiated simultaneously, and construction efficiency was low, which ensure the con- struction safety and schedule.     

Advances in numerical simulation of demolition blasting

The applications of numerical simulation in demolition blasting were reviewed. Several methods of numerical simulation in demolition blasting were introduced. The strength and weakness of the numerical meth- ods mentioned in this paper were also indicated, respectively. Furthermore, the solid lattice model in the frame of discrete element method （DEM）, which was developed by the author and his team, was detailedly described. The existed problems in the current numerical simulation methods of demolition blasting were presented and the future trend of the numerical simulation is finally prospected.     

Key technologies of precision demolition blasting of ultra-long urban viaduct in complicated surroundings

The key technologies of precision blasting were put forward based on the characteristics of urban via- duct blasting demolition in complicated surroundings. Initial bending instability mechanics model of reinforcing steel bar frame of blasting fragmented pier and sequenced collapsed dynamic model were established for quanti- tative blasting design. Technologies of water pressure blasting were applied in multi-cell box girder fragmenta- tion. The detonating network of non-electric duplication crossover was adopted for the safety and reliability of ultra-long delay. The rationality of blasting scheme and parameters were validated by physical model test. Harm- ful effects were forecasted and controlled by integrated protective technologies. Specialization, cooperation, pre- cision, execution （SCPE） project management method was put forward for precision management. The key tech- nologies of precision demolition blasting can provide reference for similar proiects.     

Precision blasting， current status and its prospective

Precision blasting, which is different from traditional control blasting, is regarded as the sign of new development stage of engineering blasting. The definition, connotation, technology system and current situa- tion of its application and development were described briefly. With regard to the prospect of precision blasting, following aspects for further study are recommended ： a. A multiple disciplinary study should be developed for a more understanding on the explosive energy release and quantitative blasting design; b. according to the require- ments of digital blasting objective, syncretic study of precision blasting and technology should be enhanced; c. numerical simulation was an important tool for optimizing engineering blasting scheme and blasting harmful effects control, a more elaborate precision numerical simulation method should be studied furthermore; d. the modernization and standardization of precision blasting construction should be enhanced.     

A new theory of rock-explosive matching based on the reasonable control of crushed zone

Rational rock-explosive matching is of great importance to enhancing explosive energy effective utili- zation and improving rock fragmentation effect. The traditionally emphasized method of acoustic impedance matching is not rational. Based on blasting breakage mechanism, a new theory of rock-explosive matching in drilling and blasting is proposed. The new approach chooses explosive parameters by reasonable control of the size of crushed zone under the condition of fully fragmentation between adjacent blast holes. This method can directly reflect the blasting fragmentation effect and energy effective utilization, which is easy to implement. Al- so, a modified model is developed, taken adjacent blast hole blasting loading into account. As a result, explo- sive parameters of different grades of rock are given in full coupling on-site mixed explosive charge for different project objectives.     

Sixty years of engineering blasting in China： Review and prospect

Based on representative blasting engineering examples, the development history of engineering blas- ting in China since 1950s was reviewed, three development phases were summarized, and the main achieve- ments of fundamental theory, engineering practice, scientific study and industry organization of engineering blasting in each phase were introduced briefly. Finally, some suggestions about the development direction of en- gineering blasting in China were given.     

Feasibility study of the transient electromagnetic method for chamber blasting misfire detection and recognition

In this paper, transient electromagnetic method was used to carry out the feasibility study on the de- tection and recognition of chamber blasting misfire. Firstly, an electromagnetic background field was estab- lished in the test; secondly, a benign conductor was preset in the chamber, and then the background field was eliminated after the electromagnetic field was measured; thirdly, the transient electromagnetic field was mea- sured again after blasting; at last, the chamber blasting misfire was detected and recognized by comparing the change of eddy current field of the preset benign conductor before and after blasting. The test results showed that： When the buried depth of aluminum box target was no more than 30 m, transient electromagnetic method can clearly identify the position of the aluminum box; when the buried depth of aluminum box was more than 30 m, the buried depth and position of the aluminum box was not sure due to the unknown level of secondary eddy current field generated by aluminum box     

Study on linear shaped charge in penetrating rock

Based on the action mechanism of linear shaped charge（ LSC ）, penetration performance of LSC on rock was studied. The optimal standoff and the vertex angle of LSC were studied and determined by lab experiments. Through cutting sand-cement grout samples, the spacing interval of boreholes can approach 17.5 times of the bore-hole＇ s diameter, and the result of the directional expansion of crack is satisfactory. The result of field experiment indicates cutting effect is very good, the ruggedness in fracture plane is less than 50 mm, the rate of half-hole marks is nearly 100 % , and the crack inspection shows that there is no damage in the internal of the cutting part. All these suggest that the orientation fracture blasting with LSC is a good means in directional fracture controlled blasting and is worth popularizing widely.     

Monitoring and analysis of shock wave in water for underwater drilling blasting

Taking the underwater reef blasting in Gulei sea channel of Xiamen Port as an example, the forming characteristic of shock wave in water for underwater drilling blasting is analyzed. By field monitoring, the pres- sure of shock wave in water for different distances is attained; the major parameters such as pressure amplitude and positive action time, and the propagation attenuation rule of shock wave in water are analyzed in this paper. The results can be helpful for engineering design and construction and environmental safety assessment.     

Measurement and characteristics of ground vibration caused by blasting demolition of urban overpass

To analyze the characteristics of ground vibration caused by blasting demolition of urban overpass, in this paper we introduced the measurement method and then studied the characteristics of recorded ground vi- brations. Through the analysis of peak acceleration, peak frequency and duration, results indicated that the ver- tical component of vibration is the most important in the region close to the collapse point; the collapse of bridge segments will lead to superposition of ground vibration, and isolation measures can reduce the peak ac- celeration but increase the duration of vibration; blasting and collapse vibration cause no damage to the re- served structure which indicates that blastin~ demolition is a safe and effective method.     

Safety analysis and control of blasting mining area adjacent to infrastructure

Systematic analysis of influence of blasting vibration on bridges, tunnels, slopes and the mechanical relationships between each other were drawn based on the example of safety argument between blasting mining area and protected objects. The safety argument methods and technological means of controlling dangerous and harmful factors were proposed by the application of principle of risk analysis. And standard control system was established based on controlling the blasting parameters of division of blasting area.     

Precision blasting excavation of rock face beam in underground hydropower station under complex geological conditions

To deal with the construction difficulties of Xiangjiaba underground hydropower station, such as complex geological conditions, narrow rock bench, high loading, high quality requirements and urgent time limit, the project adopted the concept of precision blasting. The explosive energy and rock mass fragmentation were well controlled by taking reasonable excavation sequence, designing steel pipe drilling frame, the ad- ditional techniques of double layer smooth blasting, evenly micro charge, staggered arrangement of boreholes and pre-stressed anchors. These technologies ensured the excavation quality of the rock face beam, achieving successful blasting results： Semi hole ratio was 100 % in Ⅱ surrounding rock, 99.2 % in Ⅲ surrounding rock and 90 % - 97.3 % in Ⅳ surrounding rock; underbreak was avoided and the average backbreak was only 2.9 cm; the unevenness was 0 - 4 cm; the influence depth of blasting and unloading was 0.2 - 0.7 cm.     

Research and design of the main equipments and structure of Xiangjiaba shiplift

The type of pinion and rack vertical shiplifts has been developed in recent a couple of years in the construction of dams. But the design methods and methodologies have rarely been discussed in literature. The Xiangjiaba shiplift is the second shiplift of this type following the Three Gorges shiplift. Being aimed at the technological rationality of the design in synthetically considering security, economy and applicability, this paper presents the research results of some vital issues relating the design of the Xiangjiaba shiplift, including the determination of design water depth of ship chamber based on fluid numeral computation and physical model test, the optimum design of general layout of main equipments and the civil structure of the Xiangjiaba shiplift, the finite element method （FEM） analysis of stress, vibration modes and the buckling of ship chamber, antiseismic research and the design of structures and mechanisms of the shiplift and the optimum design of driving mechanisms. This research provides the theoretical basis for the design of the Xiangjiaba shiplift. The design principles and research methods are valuable for the design of the same type of shiplifts.     

Observations of thermospheric vector wind over Yellow River Station during auroral substorm events

Strong disturbances associated with auroral substorms originate from the ionosphere-magnetosphere owing to the effects of the solar wind, and the wind field in the ionosphere is related to such substorm activity. Here, we describe the analysis of four auroral substorm events, for which we employed an all-sky Fabry-Perot interferometer to observe the two-dimensional horizontal wind field and combined the results with data from an all-sky charge-coupled device imager, a fluxgate magnetometer installed at Yellow River Station, and the Super Dual Auroral Radar Network. The results demonstrate that, during auroral substorms, the vector wind field is related closely to variations in the ion drift and geomagnetic field. Moreover, we observed a changing wind field of approximately 300 rn/s in response to variations in the electric and magnetic fields （likely caused by ion drag） and a disturbance of about 200 m/s that we attribute to the interaction of Joule heating and ion drag.     

Anomalous top-quark coupling effects in rare B and K decays

The Large Hadron Collider at CERN is performing direct searches for top-quark anomalous flavor-changing neutral current （FCNC） processes. However, these processes may be correlated closely with the low-energy rare B and K meson decays. In this paper, we review the anomalous top-quark coupling effects in these low-energy flavor transitions, summarize the flavor constraints and discuss their implications for direct detection of top-FCNC processes at the Large Hadron Collider.     

4 K high frequency pulse tube cryocooler used for terahertz space application

Terahertz(THz) frequency region, defined from0.1 to 10 THz, is an important frequency band for radio astronomy and atmospheric science. As NbN Superconductor-Insulator-Superconductor(SIS) mixers used for terahertz detection, which are studied by the Purple Mountain Observatory(PMO), Chinese Academy of Sciences(CAS), work at 8–10 K, and require condition of micro vibrations, its astronomical observation in aerospace is limited by suitable refrigeration method. 4 K high frequency pulse tube cryocooler developed by Key Laboratory of Space Energy Conversion Technologies(SECT), Technical Institute of Physics and Chemistry(TIPC), CAS, offers an opportunity for the application of SIS mixers. This article introduces the progress of the two-stage high frequency pulse tube cryocooler researched by TIPC. The cryocooler has reached a no load temperature of 4.5 K which is the lowest temperature for this kind of cryocooler reported so far. The successful coupling between the THz component and the high frequency pulse tube cryocooler lays a solid foundation for space detection in the terahertz band.     

Evaluation on Gambiered Guangdong Silk＇s Ecological Properties

To evaluate gambiered Guangdong silk＇s ecology properties, the raw materials ecology, production ecology and use ecology are analyzed; and the safety to human is tested according to GB/T18885 - 2002. Gambiered Guangdong silk is a kind of natural product. All its raw materials are reproducible and degradable natural resources, and it can decompose completely when being discarded. R is comfortable to wear, and easy to clean and dry. It is mainly manufactured by dip-dyeing in dye yam solution, and insolating under the burning sun. The production energy is solar, a kind of clean and reproducible energy. The production process is clean and environmental friendly. There is neither the utilization of synthetic dyestuff and chemical auxiliary, nor the discharge of environment pollutant, and even the dreg of dye yam is used as fuel. The safety test results show that pH value of water extract, heavy metal content （except for Pb content）, color fastness and odor meet the requirements of GB/T18885 - 2002 and Okeo-tex standard 100.     

Effect of strain rate on the compressive deformation behaviors of lotus-type porous copper

Lotus-type porous copper was fabricated by unidirectional solidification, and compressive experiments were subsequently conducted in the strain rate range of 10-3–2400 s-1 with the compressive direction parallel to the pores. A GLEEBLE-1500 thermal-mechanical simulation system and a split Hopkinson pressure bar (SHPB) were used to investigate the effect of strain rate on the compressive deformation behaviors of lotus-type porous copper. The influence mechanism of strain rate was also analyzed by the strain-controlling method and by high-speed photography. The results indicated that the stress-strain curves of lotus-typed porous copper consist of a linear elastic stage, a plateau stage, and a densification stage at various strain rates. At low strain rate (< 1.0 s-1), the strain rate had little influence on the stress-strain curves; but when the strain rate exceeded 1.0 s-1, it was observed to strongly affect the plateau stage, showing obvious strain-rate-hardening characteristics. Strain rate also influenced the densification initial strain. The densification initial strain at high strain rate was less than that at low strain rate. No visible inhomogeneous deformation caused by shockwaves was observed in lotus-type porous copper during high-strain-rate deformation. However, at high strain rate, the bending deformation characteristics of the pore walls obviously differed from those at low strain rate, which was the main mechanism by which the plateau stress exhibited strain-rate sensitivity when the strain rate exceeded a certain value and exhibited less densification initial strain at high strain rate.     

Thermoelectric properties of Al substituted misfit cobaltite Ca3（Co1-xAlx）4O9 at low temperature

Thermoelectric properties of Al substituted compounds Ca3（Co1-xAlx）4O9 （x=0, 0.03, 0.05）, prepared by a sol-gel process, have been investigated in the temperature range 305-20 K. The results indicate that after Al substitution for Co in Ca3（Co1-xAlx）4O9, the direct current electrical resistivity and thermopower increase due to the reduction of carrier concentration. Experiments show that Al substitution results in decreased lattice thermal conductivity. The figure of merit of temperature behavior suggests that Ca3（Co0.97Al0.03）4O9 would be a promising candidate thermoelectric material for high-temperature thermoelectric application.