1 Scope This standard specifies the definition, classifica- tion, technical requirements, test methods, quality ap- praisal procedure, packing, marking, transportation, stroage and quality certificate of carbon rammi...1 Scope This standard specifies the definition, classifica- tion, technical requirements, test methods, quality ap- praisal procedure, packing, marking, transportation, stroage and quality certificate of carbon ramming mate- rials for blast furnace construction. This standard is applicable to carbon ramming materials for construction in leveling layer of blast furnace bottom, ramming layer upper or lower the cen- tral line of water cooling pipes, joints between carbon bricks, or joints between carbon bricks and cooling equipment.展开更多
As wavelet basis in wavelet analysis is neither arbitrary nor unique,the same signal dealing with different wavelet bases will generate different results.Therefore,how to construct a wavelet basis suitable for the cha...As wavelet basis in wavelet analysis is neither arbitrary nor unique,the same signal dealing with different wavelet bases will generate different results.Therefore,how to construct a wavelet basis suitable for the characteristics of the analyzed signal and solve its algorithm and realization is a fundamental problem which perplexed many researchers.To solve these problems,in accordance with the basic features of the measured millisecond blast vibration signal,a new wavelet basis construction method based on the separation blast vibration signal is proposed,and the feasibility of this method is verified by comparing the practical effect of the newly constructed wavelet with other known wavelets in signal processing.展开更多
Current studies on blasting construction of small clear-distance tunnels have not considered the impact of existing tunnel lining defects when establishing safety controls.This paper offers a series of study results b...Current studies on blasting construction of small clear-distance tunnels have not considered the impact of existing tunnel lining defects when establishing safety controls.This paper offers a series of study results based on the blasting project of a new tunnel adjacent to the existing defect Xinling tunnel to thoroughly examine the dynamic response,safety control standards,and measures of the existing defect tunnel.First,structural models were developed to investigate the influence of the presence or absence of specific defects(like lining cracks and cavities behind the lining)on the dynamic response of the current tunnel lining to identify the most unfavorable defect distribution.Then,establish safety control standards for intact linings and those with the most unfavorable defects.Eventually,two types of control measures,single safe charge and reasonable delay time,were studied based on the established safety control standards.In particular,the most adverse position of cracks was the wall facing the explosion,the rise in depth was more unfavorable for vibration response,and the impact of the longitudinal crack was restricted to the vicinity of the crack.While the vault was the most adverse cavity position,the rise in cavity area was more damaging,and the influence range varied with longitudinal cavity length.Moreover,the impact of cracks was mainly evident in the amplification effect of stress at the crack region.In contrast,cavities had varied degrees of amplification effects on the vibration velocity and stress response and a relatively extensive influence range.Safety control research was conducted,when the tunnel was intact,with a right wall crack,a vault cavity,and both vault cavity and crack for this project,the peak particle velocity(PPV)of the safety control standard for vibration velocity was 13,10,13,and 8 cm/s,respectively,and the respective single safe charge could be adjusted at 64,53,37,and 25 kg.However,the presence of different defects had a relatively negligible effect on the reasonable delay time;25 ms was recommended for existing tunnel lining with and without the defect.展开更多
A protective layer(PL) is commonly reserved above foundation surface to protect the underlying rock mass during dam foundation excavation. In China, the PL of dam foundation is conventionally subdivided into two or th...A protective layer(PL) is commonly reserved above foundation surface to protect the underlying rock mass during dam foundation excavation. In China, the PL of dam foundation is conventionally subdivided into two or three thin layers and excavated with the shallow-hole blasting method, even by pneumatic pick method in case of soft rock mass. The aforementioned layered excavation of the PL delays the construction of the whole project. After nearly 30-year practices, several safe and effcient methods for the PL excavation of dam foundation are gradually developed. They include shallow-hole bench blasting with cushion material(SBC) at the bottom of the hole, and horizontal smooth blasting(HSB). The PL is even cancelled on the condition that horizontal pre-split technique is employed during dam foundation excavation. This paper introduces the aforementioned two PL excavation methods(shallow-hole blasting and bench blasting) and horizontal pre-split technique of dam foundation without protective layer(HPP). The basic principles of blasting method, blasting geometry, charge structure, drill-and-blast parameters of typical projects are examined. Meanwhile, the merits and limitations of each method are compared. Engineering practices in China show that HSB is basically the optimal method for dam foundation PL excavation in terms of foundation damage control and rapid construction. Some new problems for dam foundation PL excavation arising, such as strong unloading and relaxation phenomenon that encountered in the gorge region of southwest China, are needed to be addressed; and the corresponding countermeasures are discussed as well.展开更多
文摘1 Scope This standard specifies the definition, classifica- tion, technical requirements, test methods, quality ap- praisal procedure, packing, marking, transportation, stroage and quality certificate of carbon ramming mate- rials for blast furnace construction. This standard is applicable to carbon ramming materials for construction in leveling layer of blast furnace bottom, ramming layer upper or lower the cen- tral line of water cooling pipes, joints between carbon bricks, or joints between carbon bricks and cooling equipment.
基金Projects(51078043,51278071,51308072)supported by the National Natural Science Foundation of China
文摘As wavelet basis in wavelet analysis is neither arbitrary nor unique,the same signal dealing with different wavelet bases will generate different results.Therefore,how to construct a wavelet basis suitable for the characteristics of the analyzed signal and solve its algorithm and realization is a fundamental problem which perplexed many researchers.To solve these problems,in accordance with the basic features of the measured millisecond blast vibration signal,a new wavelet basis construction method based on the separation blast vibration signal is proposed,and the feasibility of this method is verified by comparing the practical effect of the newly constructed wavelet with other known wavelets in signal processing.
基金supported by the National Natural Science Foundation of China(Grant Nos.U2034205,and 52178397)。
文摘Current studies on blasting construction of small clear-distance tunnels have not considered the impact of existing tunnel lining defects when establishing safety controls.This paper offers a series of study results based on the blasting project of a new tunnel adjacent to the existing defect Xinling tunnel to thoroughly examine the dynamic response,safety control standards,and measures of the existing defect tunnel.First,structural models were developed to investigate the influence of the presence or absence of specific defects(like lining cracks and cavities behind the lining)on the dynamic response of the current tunnel lining to identify the most unfavorable defect distribution.Then,establish safety control standards for intact linings and those with the most unfavorable defects.Eventually,two types of control measures,single safe charge and reasonable delay time,were studied based on the established safety control standards.In particular,the most adverse position of cracks was the wall facing the explosion,the rise in depth was more unfavorable for vibration response,and the impact of the longitudinal crack was restricted to the vicinity of the crack.While the vault was the most adverse cavity position,the rise in cavity area was more damaging,and the influence range varied with longitudinal cavity length.Moreover,the impact of cracks was mainly evident in the amplification effect of stress at the crack region.In contrast,cavities had varied degrees of amplification effects on the vibration velocity and stress response and a relatively extensive influence range.Safety control research was conducted,when the tunnel was intact,with a right wall crack,a vault cavity,and both vault cavity and crack for this project,the peak particle velocity(PPV)of the safety control standard for vibration velocity was 13,10,13,and 8 cm/s,respectively,and the respective single safe charge could be adjusted at 64,53,37,and 25 kg.However,the presence of different defects had a relatively negligible effect on the reasonable delay time;25 ms was recommended for existing tunnel lining with and without the defect.
基金supported by the National Science Fund for Distinguished Young Scholars of China(51125037)the National Key Basic Research Program(973 Program) of China(2011CB013501)+1 种基金the National Natural Science Foundation of China(51279135 and 51079111)the Doctoral Scientifc Fund Project of the Ministry of Education of China(20110141110026)
文摘A protective layer(PL) is commonly reserved above foundation surface to protect the underlying rock mass during dam foundation excavation. In China, the PL of dam foundation is conventionally subdivided into two or three thin layers and excavated with the shallow-hole blasting method, even by pneumatic pick method in case of soft rock mass. The aforementioned layered excavation of the PL delays the construction of the whole project. After nearly 30-year practices, several safe and effcient methods for the PL excavation of dam foundation are gradually developed. They include shallow-hole bench blasting with cushion material(SBC) at the bottom of the hole, and horizontal smooth blasting(HSB). The PL is even cancelled on the condition that horizontal pre-split technique is employed during dam foundation excavation. This paper introduces the aforementioned two PL excavation methods(shallow-hole blasting and bench blasting) and horizontal pre-split technique of dam foundation without protective layer(HPP). The basic principles of blasting method, blasting geometry, charge structure, drill-and-blast parameters of typical projects are examined. Meanwhile, the merits and limitations of each method are compared. Engineering practices in China show that HSB is basically the optimal method for dam foundation PL excavation in terms of foundation damage control and rapid construction. Some new problems for dam foundation PL excavation arising, such as strong unloading and relaxation phenomenon that encountered in the gorge region of southwest China, are needed to be addressed; and the corresponding countermeasures are discussed as well.
