This paper analyses the fragmenting principle of static blasting agent (SBA) and the action of its cutting fragmentation. Using SBA for sterming material proved very useful and advantageous. Here we analyse in detail ...This paper analyses the fragmenting principle of static blasting agent (SBA) and the action of its cutting fragmentation. Using SBA for sterming material proved very useful and advantageous. Here we analyse in detail the cutting action of pre- stress and stress wave in pre-stressing force blasting.展开更多
Field experiments of mixed- (intercropping) and pure-planting (monoculture) of four rice varieties, representing improved hybrid varieties (Shanyou63 and Shanyou22) and high-quality traditional varieties (Huangkenuo a...Field experiments of mixed- (intercropping) and pure-planting (monoculture) of four rice varieties, representing improved hybrid varieties (Shanyou63 and Shanyou22) and high-quality traditional varieties (Huangkenuo and Zigu) from Yunnan Province, were conducted based on their differences in genetic background and agro-economical characteristics. The results demonstrated that the mixed-planting of the hybrid rice and high-quality traditional rice varieties had a significantly greater effect on controlling rice blast disease than the monoculture of these varieties, particularly the traditional ones. It is evident for the highly susceptible traditional varieties in mixed-planting to achieve disease control, with significant decreases in blast incidences and severity indexes. The blast control efficiency reached up to 83-98% under such planting model. This suggests that an appropriate mixed-planting of rice varieties with diverse genetic background and agro-economical characteristics is an effective approach for rice blast control. In addition, resistance of the traditional rice varieties to lodging was considerably increased in the plots with mixed-planting, compared with the plots with monoculture. The average rate of grain-yield increase ranged from 6. 5 to 9.7% in the plots with mixed-planting.展开更多
Controlled blasting techniques are used to control overbreak and to aid in the stability of the remaining rock formation. Presplitting is one of the most common methods which is used in many open pit mining and surfac...Controlled blasting techniques are used to control overbreak and to aid in the stability of the remaining rock formation. Presplitting is one of the most common methods which is used in many open pit mining and surface blast design. The purpose of presplitting is to form a fracture plane across which the radial cracks from the production blast cannot travel. The purpose of this study is to investigate of effect of presplitting on the generation of a smooth wall in continuum and jointed rock mass. The 2D distinct element code was used to simulate the presplitting in a rock slope. The blast load history as a function of time was applied to the inner wall of each blasthole. Important parameters that were considered in the analysis were stress tensor and fracturing pattern. The blast loading magnitude and blasthole spacing and jointing pattern were found to be very significant in the final results.展开更多
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. Thro...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.展开更多
文摘This paper analyses the fragmenting principle of static blasting agent (SBA) and the action of its cutting fragmentation. Using SBA for sterming material proved very useful and advantageous. Here we analyse in detail the cutting action of pre- stress and stress wave in pre-stressing force blasting.
基金This research was supported by the National Natural Science Foundation of China and Natural Science Foundation of Yunnan(01NG10,01C0007Z,AA211091 and 30160048)the Shanghai Commission of Education(00XD14006).
文摘Field experiments of mixed- (intercropping) and pure-planting (monoculture) of four rice varieties, representing improved hybrid varieties (Shanyou63 and Shanyou22) and high-quality traditional varieties (Huangkenuo and Zigu) from Yunnan Province, were conducted based on their differences in genetic background and agro-economical characteristics. The results demonstrated that the mixed-planting of the hybrid rice and high-quality traditional rice varieties had a significantly greater effect on controlling rice blast disease than the monoculture of these varieties, particularly the traditional ones. It is evident for the highly susceptible traditional varieties in mixed-planting to achieve disease control, with significant decreases in blast incidences and severity indexes. The blast control efficiency reached up to 83-98% under such planting model. This suggests that an appropriate mixed-planting of rice varieties with diverse genetic background and agro-economical characteristics is an effective approach for rice blast control. In addition, resistance of the traditional rice varieties to lodging was considerably increased in the plots with mixed-planting, compared with the plots with monoculture. The average rate of grain-yield increase ranged from 6. 5 to 9.7% in the plots with mixed-planting.
文摘Controlled blasting techniques are used to control overbreak and to aid in the stability of the remaining rock formation. Presplitting is one of the most common methods which is used in many open pit mining and surface blast design. The purpose of presplitting is to form a fracture plane across which the radial cracks from the production blast cannot travel. The purpose of this study is to investigate of effect of presplitting on the generation of a smooth wall in continuum and jointed rock mass. The 2D distinct element code was used to simulate the presplitting in a rock slope. The blast load history as a function of time was applied to the inner wall of each blasthole. Important parameters that were considered in the analysis were stress tensor and fracturing pattern. The blast loading magnitude and blasthole spacing and jointing pattern were found to be very significant in the final results.
文摘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.
