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The effect of cut height on collapse area is simulated and analyzed by dynamic finite element software. Meanwhile, the simulated collapse processes of the cooling tower with different cut height were completed in a parallel study, the results of which are briefly introduced in this paper. The results show that: as the cut height increases, ground vibration on surrounding structures and collapse area of cooling tower decreases. At last, numerical simulation results were used in blasting project, which reduced hazard of collapse vibration and verify the scientific of this method.

In order to fully prevent flying rocks casting to surrounding constructions in blasting demolition project, fault tree analysis was used for safety evaluation. The analysis and calculation of minimal cut sets and structure importance indicates that the highest probability of flying rock accidents is caused by large quantity of maximum priming charge. And other events come second but cannot be ignored. Thus, several measures were adopted according to the analysis result and the final blasting result showed that no flying accidents happened in the whole process.

Emulsion explosive is one of common industrial explosives, its performance ability is important for producer. So the experiment and theory analysis were made to improve the performance ability of emulsion explosive in this paper. The results show that: performance ability of explosive becomes bigger when oxygen balance of explosive is zero or slightly negative; Water content also has a significant impact on stability, density and explosive performance of emulsion explosive; performance ability of emulsion explosive is generally rises with density increasing. The key approaches of improving the performance ability are that improving the explosion heat and hematocrit and selecting appropriate moisture content and density, and advanced process technology also should be put to use.

In order to resolve the problems that many units are intersect and mutual restraint in the safety evaluation of emulsion explosive continuous manufacturing, the safety evaluation model based on uncertainty measurement theory was built, then this model was used to evaluate the safety of emulsion explosive continuous manufacturing in one explosive industry. The evaluation results show that: the information entropy and confidence identifying criterion were respectively used to ascertain the evaluation index weight and identifying criterion, by these ways, the evaluation results of this model are more objective; and the evaluation units can be selected flexibly according to actual situation, the calculation of evaluation model is simple, so the evaluation results can offer decision basis for explosive industry to make good management.

In order to resolve the uncertainty problem of influence factors in effect evaluation of bench blasting, the effect evaluation model of bench blasting based on uncertainty measurement theory was built, then this model was used to evaluate the bench blasting effect in Hongshuitai flat engineering. The evaluation results show that: the information entropy and confidence identifying criterion were respectively used to ascertain the evaluation index weight and identifying criterion, by these ways, the evaluation results of this model are more objective; and the evaluation index can be selected flexibly according to actual situation, the calculation of evaluation model is simple, so the evaluation results can offer decision basis for blasting workers to make timely adjustment of the blasting scheme.

Repeated experiments were done to study of influence of sensitization process on quality of mixed loading emulsion explosive, the results show that: The ratio of the sensitizing agent at 1:10 ~1:30 are more appropriate; the density of mixed loading emulsion explosive is gradually decreased while concentration of sensitizing agent increased. Emulsion explosive quality is affected by foaming time under the condition of the certain proportion of sensitizer and constant temperature, when the sensitizer mixing time extended to a certain value, the density tends to be stable. Under the condition of invariable sensitizer concentration, proper temperature not only obtain good blasting effect, but also improve the charging efficiency and shorten the charging time; the temperature between 30~50 °C is more appropriate when the ratio of sensitizer is certain.

Based on the finite element model of slope, the stability of sand slope are studied. The results show that The pore water pressure shows increase trend, while the excess pore water pressure shows decreasing trend with the increase of the water depth. With the increase of the the water depth, safety factor of slope calculated by quasi static reduces to 0.193 from 2.366, which reduces 12.26times. The minimum safety factor calculated by dynamic time history is less than that by quasi static method, which shows that there is some limitations of the quasi static method.Without considering the groundwater, the destruction of slope is mainly the circular shearing damage through the slope toe, while the destruction is not yet through the slope toe, but from a point on the front of slope.

Based on the discrete element numerical simulation, the change of failure modes of slope influenced by parameters of rock mass structural plane is studied. It is shown the failure modes shift gradually from the bedding sliding failure modes to the sliding-bending failure modes with the increase of the strength of the rock mass structural plane; The slope failure modes are mainly sliding failure modes with the increasing of the normal and shear stiffness and spacing of rock structural plane. Failure modes shift from shearing slip failure modes to shearing slip and buckling failure modes and finally to the tilting failure modes with the increase of the rock structural plane dip angle. The impact of the rock structural plane cohesion to the slope stability is the greatest, and the stiffness is the least.

Based on the finite element model of the tunnel, dynamic response of tunnel is studied influenced by different confining pressure and different surrounding rock types under of blasting vibration under blast vibration load. The results show that when the confining pressure increases, the maximum horizontal and vertical vibration velocity, stress and displacement increase, and the horizontal vibration amplitudes are less than the vertical vibration amplitudes. With the decreasing of the rock type, the vertical vibration velocity peak value increases, and vertical direction vibration velocity is more sensitive for the rock stress state. With the increase of depth of surrounding rock, the confining pressure increases, and the vertical velocity response signal of surrounding rock increases, and the response signal is more sensitive to the change of stress of surrounding rock compared with the horizontal vibration velocity peak.

In order to further improve the accuracy of the numerical simulation technology in buildings blasting demolition, numerical simulations on seven-story frame structure blasting demolition process were carried out adopting separate common node reinforced concrete model, and two simulation methods between the concrete elements on cut site directly removed and the concrete elements on cut site reserved with explosive loading applied instead were comparative analyzed. Simulation result indicates that, separate common node model can reflect mechanical properties difference of concrete and reinforcement through analysis on their loading process. There would be an upward impact force on the structure at the moment of detonating when the concrete elements on cut site were reserved with explosive loading applied instead, and it made the whole structure collapsed process extend about 0.5 s and structure touchdown vibration increase about 2.39 times. It had a negative impact on blasting vibration control, so the applied explosive blasting on cut site become a factor to be considered on the numerical simulation of structure blasting demolition. Studies suggest that the applied explosive blasting on the numerical simulation of structure blasting demolition can simulate the collapse process of building blasting demolition more real and will be an better aided design of structure blasting, and it has important engineering practical value.

In blasting excavation of shallow tunnel, the surface vibration of excavated tunnel can be amplified due to effect of hollow. This effect is an important factor for safety of surface buildings. Based on the measured data of one tunnel excavation project, combining wavelet analysis and AOK time-frequency distribution method, the surface vibration signals in front and rear position of working face are processed into different frequency bands. Taking PPV, dominant frequency, d7 (7.8125-15.625 Hz) band energy ratio and d7 (7.8125-15.625 Hz) band energy duration as indexes, the effect of hollow on time-frequency characteristics of surface vibration signal is studied in this article. The results show that, affected by the hollow in excavated region, the PPV and dominant frequency increase, and the d7 (7.8125-15.625 Hz) band energy shows fluctuant ratio of total energy and an increase of band energy duration. The results show that the hollow influence on the frequency characteristics of the surface vibration signals comprehensively, and also provide an analytical basis for anti-vibration and vibration reduction study from the angle of energy.

In order to ensure one through arch rib road bridge blasting demolition will go well, using separate common node reinforced concrete model, numerical simulate the process of bridge collapsed and disintegrate, at the same time, analyze the stress state of steel and concrete unit in detail. The simulation results show that separate common node model could reflect the mechanical properties difference of steel and concrete materials; destruction of the support part of bridge and joint parts reserved , meanwhile, blasting treatment of the joint parts of derrick and arches, also arch center derrick and deck beams, arch springing hinge inside pier reserved on the left, it can ensure the bridge collapsed and broken fully, and can reduce the stack height of bridge collapsed in the river. The research considers that researching on structure collapse process by numerical simulation method not only reappear the process of collapse, but also forecast collapse result in schematic design phase. It will become the important means of study the structure mechanics process of blasting demolition and guide assisted the design of structure blasting demolition, which has important engineering practical value.

Objectives We performed a systematic review and meta-analysis to assess the effects of physical activity in preventing gestational diabetes mellitus (GDM). Search strategy We searched the literature in six electronic databases and bibliographies of relevant articles. Selection criteria We included randomised controlled trials on pregnant women who did not have GDM and other complications previously and had increased physical activity as the only intervention. The risk of developing GDM was documented separately for the intervention and control groups. Data collection and analysis Two reviewers extracted data and assessed quality independently. Data from the included trials were combined using a fixed-effects model. The effect size was expressed as relative risk (RR) and 95% CI. Main results Of the 1110 studies identified, six randomised controlled trials met the inclusion criteria. In three trials, the incidence of GDM was lower in the intervention group than in the control group, whereas two trials showed a higher incidence of GDM in the intervention group and the remaining trial found no GDM in either the intervention or control group. The meta-analysis resulted in a relative risk (RR) of GDM of 0.91 (95% CI 0.57 to 1.44), suggesting no significant difference in the risk of developing GDM between the intervention and the control groups. No indication of publication bias was found. Conclusions Evidence was insufficient to suggest that physical activity during pregnancy might be effective to lower the risk of developing GDM.

In the late part of the 20th century, due to the change of disease spectra, rapid increase of health expenditure and imbalanced distribution of health resources, the health management sectors and doctors increasingly demand the scientific decision-making. With the development of clinical evidences and research, evidence-based medicine (EBM) became emerged in the early 1990's. EBM, the medical science in compliance with the best available clinical evidence, integrates clinical epidemiology (CE), systematic reviews (SRs) and health technology assessment (HTA) as the major technology, to emphasize that the clinical practice should be based on the combination of the best available clinical evidence, medical experiences and patient desire to cope with the demand of medical decision-making. Some governments and international organizations like WHO, and Australia have now adopted the high-quality evidence of EBM for decision-making. As the largest developing country, China is challenged by variety of health problems. The introduction, adaptation and implementation of EBM will improve the decision-making and health care services, which should enhance the competitive capacity of medical and pharmaceutical manufactures, as well as promote the popularization of EBM, and protect the doctors and patients rights.