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Copyright of Journal of Railway Science & Engineering is the property of Journal of Railway Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The classification of surrounding rock is crucial for formulating safe tunnel construction plans and support measures. However, the complex geological environment of tunnels presents a challenge in obtaining accurate drilling parameters for rock mass classification. This paper presents the development of a rock drilling testing system, which includes a propulsion speed acquisition system, oil pressure acquisition system, air pressure acquisition system, and an automatic data acquisition system. This system enables real-time, high-precision automatic collection and storage of parameters such as propulsion speed, with data collected twice per second for each parameter. Leveraging the Qingdao Metro Line 6 as a case study, we conducted rock mass drilling and constructed a rock mass classification database. By employing kernel density estimation and Pearson correlation analysis, we quantified the correlation between rock mass classification and the drilling parameters. The results indicated that relying on a single drilling parameter is insufficient for accurately determining rock mass classification. Both impact pressure and rotational pressure showed the strongest correlation with rock mass classification, each with a correlation coefficient below −0.8 (indicating a strong negative correlation). Outlier values of drilling parameters were excluded using the interval method. Based on the remaining data, we established an intelligent rock mass classification model using the random forest algorithm. This model demonstrated good accuracy and generalization performance, with an average accuracy exceeding 0.9. The proposed rock drilling testing system, combined with the intelligent rock mass classification model, forms an integrated system for the intelligent identification of rock mass grades. This system has significant implications for the intelligent and safe construction of drill-and-blast tunnels. [ABSTRACT FROM AUTHOR]

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract The burgeoning development of railway construction in plateau regions of southwest China necessitates innovative and environmentally sustainable approaches, particularly in the realm of tunnel construction, where the transfer of muck poses significant operational and environmental challenges. This research, pivoting around the application and configuration of electric muck transfer equipment in plateau railway tunnels, seeks to dissect the potentialities and impediments of transitioning from conventional diesel-powered machinery to electric alternatives, with a spotlight on mitigating environmental impacts and enhancing operational efficiency. Through an analytical lens, the study employs a case study methodology, leveraging data and insights from existing electric equipment models and their applications, provided by major manufacturers in China, to weave a comprehensive narrative around the practicalities, specifications, and challenges embedded in the adoption of electric machinery in plateau environments. The findings unveil a nuanced landscape, where the environmental and operational advantages of electric equipment are juxtaposed against a backdrop of technological, financial, and infrastructural hurdles, thereby crafting a complex tapestry of opportunities and challenges. The research further extrapolates policy recommendations and practical guidelines, advocating for a harmonized amalgamation of governmental policies, technological advancements, and strategic planning to navigate through the identified challenges and optimize the integration of electric equipment in tunnel construction practices. Envisaging future research pathways, the study underscores the criticality of perpetuating technological innovations, policy adaptations, and interdisciplinary research to further refine and enhance the application of electric muck transfer equipment in plateau railway tunnel projects, thereby contributing to the broader narrative of sustainable construction practices in challenging terrains.

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study conducts numerical simulations to analyze the influence of the distance between roadway and fault fracture zone on the stability of excavation roadway surrounding rock during parallel roadway excavation with using the drilling and blasting method in the Julong Copper Mine. Numerical simulation models are established for different distances between roadway and fault fracture zone, and the variations in the displacement field, stress field, and plastic zone are analyzed. The numerical simulation results show that when the distance between roadway and fault fracture zone is 1 m and 4 m, the fault fracture zone has a significant impact on the stability of the surrounding rock of the roadway, with the maximum displacement values of the roadway side wall being 6. 19 cm and 1. 13 cm respectively. The maximum principal stress is concentrated in the left side surrounding rock of the roadway, with lesser stress in the right side surrounding rock. Horizontal stress is concentrated at the intersection of the surrounding rock and the fault fracture zone, and plastic deformation occurs within the fault fracture zone. When the distance between the roadway and the fault fracture zone is 7 m and 10 m, the influence of the fault fracture zone on the stability of the surrounding rock of the roadway is minor, with the maximum principal stress and horizontal stress approximately symmetrically distributed along the centerline of the influence, and no plastic deformation occurs within the fault fracture zone. [ABSTRACT FROM AUTHOR]

The burgeoning development of railway construction in plateau regions of southwest China necessitates innovative and environmentally sustainable approaches, particularly in the realm of tunnel construction, where the transfer of muck poses significant operational and environmental challenges. This research, pivoting around the application and configuration of electric muck transfer equipment in plateau railway tunnels, seeks to dissect the potentialities and impediments of transitioning from conventional diesel-powered machinery to electric alternatives, with a spotlight on mitigating environmental impacts and enhancing operational efficiency. Through an analytical lens, the study employs a case study methodology, leveraging data and insights from existing electric equipment models and their applications, provided by major manufacturers in China, to weave a comprehensive narrative around the practicalities, specifications, and challenges embedded in the adoption of electric machinery in plateau environments. The findings unveil a nuanced landscape, where the environmental and operational advantages of electric equipment are juxtaposed against a backdrop of technological, financial, and infrastructural hurdles, thereby crafting a complex tapestry of opportunities and challenges. The research further extrapolates policy recommendations and practical guidelines, advocating for a harmonized amalgamation of governmental policies, technological advancements, and strategic planning to navigate through the identified challenges and optimize the integration of electric equipment in tunnel construction practices. Envisaging future research pathways, the study underscores the criticality of perpetuating technological innovations, policy adaptations, and interdisciplinary research to further refine and enhance the application of electric muck transfer equipment in plateau railway tunnel projects, thereby contributing to the broader narrative of sustainable construction practices in challenging terrains. [ABSTRACT FROM AUTHOR]

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To accurately predict the advance of a tunnel excavated by the drilling and blasting method, various parameters related to the rock and the operational conditions of the project should be taken into account. In this paper, a comprehensive model was developed to investigate the effects of different parameters on the advancement of such a tunnel. To achieve this goal, we conducted a systematic study at the tailrace tunnel of the Azad Dam in Iran. Rock properties, including the rock mass rating (RMR) and tunneling quality index (Q), as well as operational conditions such as blasting specific charge (q) and tunnel face area (A), were measured to establish comprehensive datasets for prediction. A total of 86 tunneling data points were collected and considered in this study. A novel model was developed, combining multiple regression (MR) and rock engineering systems (RES), to estimate tunnel face advance. The RES coding method was improved by incorporating a multiple regression model. The proposed coding method creatively assesses the influencing parameters, providing the advantage of accommodating uncertainties in the RES analysis. It achieves this by modeling the relationship between the explanatory (independent) variables and response (dependent) variables, thereby quantifying the interaction matrix. To evaluate the accuracy of the proposed models for both MR and RES datasets, we used the coefficient of determination (R2), a significant statistical criterion. A comparison of the values predicted by the models demonstrated that RES offers a more suitable performance than MLR for predicting tunnel advance. Sensitivity analysis of the MR-RES models reveals that the effective parameters on tunnel advance, in descending order of influence, are RMR (35.62%), Q (28.6%), q (20.35%), and A (15.42%). This hybrid method can be developed in other fields of engineering without human judgment and considering the statistical background of the data.

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The classification of surrounding rock is crucial for formulating safe tunnel construction plans and support measures. However, the complex geological environment of tunnels presents a challenge in obtaining accurate drilling parameters for rock mass classification. This paper presents the development of a rock drilling testing system, which includes a propulsion speed acquisition system, oil pressure acquisition system, air pressure acquisition system, and an automatic data acquisition system. This system enables real-time, high-precision automatic collection and storage of parameters such as propulsion speed, with data collected twice per second for each parameter. Leveraging the Qingdao Metro Line 6 as a case study, we conducted rock mass drilling and constructed a rock mass classification database. By employing kernel density estimation and Pearson correlation analysis, we quantified the correlation between rock mass classification and the drilling parameters. The results indicated that relying on a single drilling parameter is insufficient for accurately determining rock mass classification. Both impact pressure and rotational pressure showed the strongest correlation with rock mass classification, each with a correlation coefficient below −0.8 (indicating a strong negative correlation). Outlier values of drilling parameters were excluded using the interval method. Based on the remaining data, we established an intelligent rock mass classification model using the random forest algorithm. This model demonstrated good accuracy and generalization performance, with an average accuracy exceeding 0.9. The proposed rock drilling testing system, combined with the intelligent rock mass classification model, forms an integrated system for the intelligent identification of rock mass grades. This system has significant implications for the intelligent and safe construction of drill-and-blast tunnels.

In rocky road drilling and blasting in coal mines, the key to work efficiency is cutting. Although blast hole depth has steadily increased with increasing rocky road excavation activities, the cut hole depth is still ordinarily shallow, which is normally kept at 200 mm or less. Using an intelligent design system, a key technology, and equipment matching research of a drilling and blasting method in the Huainan mining area as the engineering background, this paper conducts research on the overdepth coefficient of cutting holes and the optimization of cutting-blasting parameters, aiming at the excessive number of full section blast holes in the mining area and the randomness and irrationality of blast hole layout. The overdepth coefficient, η, was obtained by theoretical derivation, numerical modeling, field testing, and monitoring. Based on this, the coincidence degree of fracture area, φ, is also introduced. This paper analyzes the rock stress state and stress wave attenuation phenomenon during blasting with different overdepths, establishes the relationship between the overdepth and stress between cut holes, determines the calculation formula and value range of the key parameters of the cut cavity, and investigates whether there is an optimal cut hole overdepth coefficient. The coincidence degree with fracture area increases the explosive blasting energy utilization rate and provides a theoretical basis for decreasing the charge and number of holes while retaining the blasting impact. The propagation law of explosion stress wave and the distribution and evolution law of effective stress in rock mass during overdepth blasting of cutting holes at different depths are explored using LS-DYNA numerical simulation, and the variation characteristics of stress wave intensity at different overdepth stress measuring points are compared, based on the geomechanical parameters of surrounding rock in Gubei Coal Mine. The effect of varying cut hole depths on the free surface after blasting and the blasting effect is revealed; overdepth blasting schemes of 200, 300, 400, and 500 mm are applied to the rocky road excavation site. The blasting effect indicators such as single cycle footage, blast hole utilization rate, explosive unit consumption, block rate of each overdepth blasting scheme, and ordinary blasting scheme are compared, and the effect of different overdepths on the quality and effect of cutting-blasting is compared and analyzed. On this premise, the blast hole layout is refined further, the number of blast holes is reduced, and the optimal blasting scheme is determined. The results show that the coincidence degree of fracture area increases as the overdepth coefficient increases, and the blast hole utilization rate initially increases and then decreases as the overdepth coefficient increases, between 0.17 and 0.22, causing the blast hole utilization rate to the peak. This theory proposes a novel approach to increasing the blast hole utilization rate. When the depth of the overdepth is 400 mm, The blasting energy is primarily used to create a crack area around the cut hole, which provides enough free surface for the subsequent central hole and auxiliary hole blasting, reduces the difficulty of rock breaking, increases the volume of the blasting chamber, and facilitates subsequent rock throwing. Simultaneously, the effective stress of each measuring point decays slowly with time, the average stress is higher, and the tensile fracture effect of the stress wave on the surrounding rocks increases and prolongs, creating a complete and even rock mass fracture. The blast hole utilization rate reaches the maximum of 95.2%, the bulk rate and explosive unit consumption are significantly reduced, the rate of half-hole mark rate is significantly increased, and the road construction quality is good. It demonstrates that ultra-deep blasting can enhance not only the blast hole utilization rate but also the blasting impact and road construction quality, which has some guiding significance for the parameter optimization of rocky road drilling and blasting construction.

In view of the problem that high concentration of dust is easily generated during rock tunnel drilling and blasting construction, explosive water mist to reduce dust is given in this paper. Water bag is set up on tunnel face and explosive water mist is used to reduce blasting dust concentration. With the help of numerical simulation software FLUENT and combined with theoretical analysis, The key parameters of explosion fog and dust reduction technology are obtained: water bag spacing, blasting time difference, water bag layout position, etc., which provides a theoretical basis for practical application of the technology. At the same time, combined with the field test of Huangtai tunnel blasting, the dust concentration with and without water mist was measured, respectively. The results show that the maximum dust removal rate of the tunnel section under the dust removal measures with water mist can reach 80.85%, the average dust removal rate can reach 65.16%. So, the dust removal effect is remarkable. [ABSTRACT FROM AUTHOR]

The demand for tunnel construction continues to grow by leaps and bounds. Therefore, tunnel mechanization construction is receiving more and more attention for improving excavation ergonomics. To enhance the scientific and comprehensive evaluation results of tunnel drilling and blasting method excavation ergonomics, a set of evaluation methods of tunnel drilling and blasting method excavation ergonomics based on the game theory G2-EW-TOPSIS model is proposed. From the three dimensions of drilling efficiency, construction process duration, and synergistic influence factors, a tunnel drilling and blasting construction ergonomics evaluation index system consisting of 11 indicators such as perimeter hole drilling efficiency, drilling duration, construction quality, and comprehensive cost is constructed. The subjective and objective weights of evaluation indicators are calculated by using the improved sequential relationship analysis method (G2 method) and entropy weight method, respectively, and the combination weights are carried out by using game theory method (GTM) with the Nash equilibrium as the goal. The indices are classified into five grades: excellent (I), good (II), average (III), rather poor (IV), and poor (V), according to the daily tunnel construction. The excavation ergonomics index to be evaluated is calculated using the combined weights, and the comprehensive evaluation index of excavation ergonomics to be evaluated is calculated using the technique for order preference by similarity to an ideal solution (TOPSIS). The proposed rating model was used to analyze the excavation ergonomics of the Shangtianling Tunnel in the Chizhou–Huangshan High-Speed Railway using jumbo drills (JD) and drilling machines (DM) in large- and small-mileage construction, respectively, and to obtain the excavation ergonomics rating and comprehensive evaluation rating of each evaluation object. The research results show that the established excavation ergonomics evaluation model can effectively identify the main factors affecting the excavation ergonomics of the drill and blast method, and has a certain reference value. [ABSTRACT FROM AUTHOR]

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Railway Science & Engineering is the property of Journal of Railway Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Engineering Geology / Gongcheng Dizhi Xuebao is the property of Journal of Engineering Geology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The demand for tunnel construction continues to grow by leaps and bounds. Therefore, tunnel mechanization construction is receiving more and more attention for improving excavation ergonomics. To enhance the scientific and comprehensive evaluation results of tunnel drilling and blasting method excavation ergonomics, a set of evaluation methods of tunnel drilling and blasting method excavation ergonomics based on the game theory G2-EW-TOPSIS model is proposed. From the three dimensions of drilling efficiency, construction process duration, and synergistic influence factors, a tunnel drilling and blasting construction ergonomics evaluation index system consisting of 11 indicators such as perimeter hole drilling efficiency, drilling duration, construction quality, and comprehensive cost is constructed. The subjective and objective weights of evaluation indicators are calculated by using the improved sequential relationship analysis method (G2 method) and entropy weight method, respectively, and the combination weights are carried out by using game theory method (GTM) with the Nash equilibrium as the goal. The indices are classified into five grades: excellent (I), good (II), average (III), rather poor (IV), and poor (V), according to the daily tunnel construction. The excavation ergonomics index to be evaluated is calculated using the combined weights, and the comprehensive evaluation index of excavation ergonomics to be evaluated is calculated using the technique for order preference by similarity to an ideal solution (TOPSIS). The proposed rating model was used to analyze the excavation ergonomics of the Shangtianling Tunnel in the Chizhou–Huangshan High-Speed Railway using jumbo drills (JD) and drilling machines (DM) in large- and small-mileage construction, respectively, and to obtain the excavation ergonomics rating and comprehensive evaluation rating of each evaluation object. The research results show that the established excavation ergonomics evaluation model can effectively identify the main factors affecting the excavation ergonomics of the drill and blast method, and has a certain reference value.

The closely spaced tunnels structure has been widely used in traffic tunnels, hydropower stations, collieries and underground metal mines. Blasting has important implications for the construction of these closely spaced tunnels. Due to the effect of multi-free surfaces and the appearance of excavation damaged zones (EDZs), the propagation and attenuation of blast vibration are expected to be more complex than in ordinary separated tunnels. In this study, field tests including ultrasonic tests and vibration tests were conducted during the excavation process of a closely spaced tunnels project, then a series of three-dimensional dynamic calculations considering explosive velocity detonation were conducted to study the propagation and attenuation of blast vibration. The results indicate that in closely spaced tunnels, EDZs have evident amplification effects on the vibration intensity, especially on the Rayleigh waves propagating longitudinally. The small clear distance and larger dimensionless wavenumber lead to the asymmetric distribution of vibration velocity, and the side wall located in the wave incident side is more easily damaged. In tunnel blasting, the maximum Peak Particle Velocity often appears around the heading face, while the maximum value appears at 1.5–3.0 m behind the heading face section for adjacent tunnels. The results of this study can be applied in the design of blasting and monitoring scheme of closely spaced tunnels. [ABSTRACT FROM AUTHOR]

Copyright of Nonferrous Metals (Mining Section) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Overbreak and underbreak predictions can be used to effectively control blasting formation of rock roadways and to maintain roadway stability. In this paper, the profile of the roadway after blasting is simplified using fractal theory and quantitative relationships between the overbreak and underbreak block sizes and fractal dimensions are derived. A model for predicting the fractal dimensions of the roadway profile after blasting is proposed. The model demonstrated good accuracy and applicability in field tests. After blasting, rock roadways of coal mines are generally dominated by overbreak. This phenomenon is particularly prominent in soft rock roadways. Contours of the surrounding rock after blasting can be approximated as two fractal structures. Decreasing quality of formed roadways can lead to a highly complex surrounding rock profile, that is, a larger fractal dimension. In addition, the distribution of the volume of overbreak or underbreak approximately follows the Weibull distribution and the surrounding rock quality greatly influences the fractal dimension distribution. Poor rock quality results in a wider distribution of the volume of overbreak or underbreak. The fractal model for roadways with a typical lithology can be used to predict the distribution of overbreak and underbreak block sizes of roadways varying surrounding rock conditions, which can guide roadway construction in the field and ensure good blasting effects. The model showed that directional control blasting technology can reduce the size and discreteness of the roadway overbreak and underbreak in a test roadway and flatness of the roadway was significantly improved. This prediction model is suitable for establishing an overbreak (underbreak) warning and preventing system and it will be utilized as a foundation reference for a practical drift blasting reconciliation at mines for operation improvements. [ABSTRACT FROM AUTHOR]

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In recent years, experimental and numerical researches on the effect of blasting pressure on the stability of existing tunnels was widely obtained. However, the effect of the blasting pressure during excavation a new tunnel or expansion old tunnels on an existing tunnel has disadvantages and still unclear. Some researches were carried out to study the relationship of the observed Peak Particle Velocity (PPV) on the lining areas along the existing tunnel direction, due to either the lack of in situ test data or the difficulty in conducting field tests, particularly for tunnels that are usually old and vulnerable after several decades of service. This paper introduces using numerical methods with the field data investigations on the effect of the blasting in a new tunnel on the surrounding rock mass and on the existing tunnel. The research results show that not only predicting the tunnel lining damage zone under the impact of blast loads but also determination peak maximum of explosion at the same time at the surface of tunnel working. [ABSTRACT FROM AUTHOR]

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Relevance of the work is caused by necessity of economic and social development, providing operating companies with a source of raw materials. The drilling-and-blasting method is the most productive. This method is the basic and still the most perspective mode of collapse of strong, especially strong rocks, when carrying out mountain and prospecting and operational developments. There are many factors which influence the efficiency of drilling-and-blasting operations, the geological specification is the main one. Annually the rates of prospecting surveys increase. Therefore there is a requirement of increasing penetration speed. At this stage the increase of penetration speed is achieved by introduction of new equipment and technology. Mining exploration production in mining industry is carried out by the traditional cyclical technology using drilling and blasting method for separating rocks from the array. This technology has not undergone significant change over a long period. The total time required for hole drilling is in the range of 30…40 % and 50…60 % at ore deposit exploration within cycle time balance. Thus, for the last 10-20 years, no significant changes occurred in the time distribution. However, the absolute values of drilling duration decreased in 2-3 times because of application of more powerful drilling machines, mounting devices, improving work organization. The important and actual task is searching for new directions in increasing the efficiency, quality and profitability of drilling-and-blasting operations due to optimization of technological and technical indicators. The aim of the work is to develop and to select the technology of drilling-and-blasting operations with direct burn cuts applying geological structural features of the massif.

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The excavation of large-span triple tunnels using drilling and blasting method inevitably causes complicated load transfer effects and induces potentially damaging ground vibrations. In this study, the structural responses (including the surrounding rock pressure, normal-contact pressure between the primary and secondary linings, internal forces in the secondary lining) and the seismic responses (including peak particle velocity and corner frequency), are systematically recorded. It is found that the first-excavated left tunnel is influenced heavily by the excavation of the last-excavated middle tunnel, whereas it is hardly affected by the excavation of the second-excavated right tunnel. The load carried by the primary lining is approximately three times as that carried by the secondary lining. The middle tunnel was in the least desirable state due to the formation of the large Protodyakonov's equilibrium arch (PEA). Based on timely feedback of the comprehensive monitoring system, a series of vibration-reducing techniques were applied and effectively guaranteed safety during blasting construction. By referring to Chinese codes, the minimum safety factor of the secondary lining is 1.3; the maximum PPV (0.15 cm/s) is lower than the allowable value; and the corner frequency (40-140 Hz) will not cause resonant vibration of the Great Wall. [ABSTRACT FROM AUTHOR]

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)