Blast Method Research Articles

Mechanism and Influencing Factor Analysis of Near-Well Stimulation for Hot Dry Rock Reservoirs by Liquid CO2 Phase Transition Blasting: Applied to Matouying Uplift.

To improve the heat transfer efficiency of the hot dry rock (HDR) well group, a near-well stimulation method of liquid CO2 phase transition blasting (LCO2-PB) is put forward, the fracturing characteristics and mechanism of samples induced by impact dynamic load are analyzed, the effects of hydraulic fracturing cracks, buried depth, shock wave amplitude, and blasting frequency on the reservoir stimulation are clarified, and feasible suggestions have been proposed for its on-site application. Results show that the dynamic load applied by LCO2-PB can effectively increase the number and connectivity of cracks and enhance the complexity of damaged cracks. The existence of hydraulic fracturing cracks has a promoting effect on the generation and distribution because blasting stress wave can reflect and refract in the hydraulic fracturing cracks and torn apart the surrounding area. The buried depth has a suppressive effect on the impact range of blasting because its increases the difficulty of reservoir crack initiation. The shock wave amplitude of LCO2-PB is beneficial for the fracturing effect of the reservoir while it also increases the risk of wellbore damage. There is a linear positive correlation between the blasting frequency and the crack zone area, and there is an optimal blasting frequency to form a connected crack network and avoid serious damage to the wellbore. For HDR reservoirs with large buried depth, prefracturing, increasing the shock wave amplitude, and selecting the appropriate blasting frequency can significantly improve the near-well stimulation effect and promote the exploitation of HDR resources.

A Comparative Study of Supervised Machine Learning Techniques for Water Leakage Prediction in Drill and Blast Excavated Water Tunnels in the Himalayan Region

In the Himalayan region, drill and blast (DB) method excavated water tunnels often pass through complex geological rock mass conditions which were formed with frequent tectonic movements. Due to these tectonic movements, the rock mass conditions in the Himalayas are highly faulted, folded, jointed, sheared, and fractured. The geological formations are the pathway for the water ingress and leakage out in the water tunnel. This water leakage in the tunnel causes a complicated geological hazard, which significantly increases tunnel instability and can lead to a delay in completion time and finally increase the cost of the tunnel project. Therefore, an efficient water ingress/leakage prediction model is essential to mitigate these challenges. In this research, various field data such as rock mass properties, topography, and permeability data sets were collected from the Nilgiri-II Hydroelectric project water tunnel. These real-time field datasets have been used for comprehensive assessment and to predict the water ingress/leakage in the water tunnel by using four supervised machine learning (ML) approaches such as Support Vector Regression (SVR), Decision Tree (DT) regression, K-Nearest Neighbors (KNN) and Random Forest (RF) regression models. It was observed that the KNN shows the best regression performance of 93% followed by RF of 92%, DT of 86%, and SVR of 66%. Therefore, all these machine learning approaches show good performance in predicting water ingress/leakage based on real field data except the SVR model.

Определение напряженного состояния массива горных пород взрывным и виброакустическим методом

In order to ensure safety at the level of -250 m in the Gubkin mine of KMAruda, the following activities were performed: assessment of the rock mass susceptibility to rock bumps using the vibroacoustic method, as well as determination of the stress state of the rock mass with the blasting method. As the result of experimental studies using the vibroacoustic method, a decrease of the stress state of the rock mass was found to vary from 17.5–92.5 MPa (at the entry contour) to 10–30 MPa at the distance of 1.8 m from the wall. The blasting method used at the level of –250 m of the Gubkin mine revealed that the stress state of the rock mass at the bottoms of the cutting and auxiliary holes is 21.9–33.5 MPa, while at the bottoms of the outer and trimming holes it varies within 55.7–65.1 MPa. The blasting and vibroacoustic methods for determining the stress state of the rock mass are similar in the physics of the process. When exposed to the detonation products or the drilling tools combined with the static rock pressure, a certain volume of rock mass is destroyed. The greater the static rock pressure, the greater the volume of destruction is under the same dynamic loads. Taking into account an increase of the stress state from the center towards the outline for the rock face plane, a numerical assessment of the stress state at the entry contour after blasting of the cutting, auxiliary and outer holes was carried out based on a theoretical formula. The calculations using the formula and based on the test data coincide, which indicates creation of residual stresses within the rock mass due to the sequential detonation of the explosive sets in the blast holes.

Phylogenetic and phylodynamic analysis of respiratory syncytial virus strains circulating in children less than five years of age in Karachi-Pakistan

BackgroundRespiratory syncytial virus (RSV) is one of the leading causes of infant morbidity and mortality worldwide, especially in Pakistan. To date, few studies have explored RSV epidemiology in different areas of Pakistan. However, none have performed comprehensive phylogenetic and phylodynamic analyses of RSV strains. This study presents a comprehensive genetic and phylodynamic analysis of RSV strains in children under five years in Karachi, Pakistan. MethodsThis study used retrospectively collected nasopharyngeal (swab) samples from 155 children with qPCR-confirmed RSV infection. The samples were used to perform RSV genotyping using PCR employing RSV glycoprotein gene-specific primers. The RSVA and RSVB genotyping was performed using BLAST and Maximum-likelihood (ML) phylogenetic methods. Similarly, the relationship with other RSV strains was analyzed using ML phylogenetic cluster analysis. The RSVA and RSVB mean genetic diversity and coefficient of differentiation were calculated using MEGA7 software. Furthermore, the time to the most common recent ancestor (tMRCA) and effective population size of RSV genotypes A and B were estimated using a Bayesian MCMC analysis. Finally, site selection pressure and glycosylation analyses were performed using FUBAR and NetNGlyc/NetOGlyc tools. ResultsOut of 155, 98 and 57 sequences were RSVA and RSVB, respectively. The tMRCA was estimated to be around 2002 and 2005 for RSVA and RSVB, respectively. RSVA sequences formed two NA1 genotype clusters, comprising 95 and three sequences, respectively. RSVB formed three clusters, where 24 and two sequences clustered with BA9 and BA12 genotypes, respectively, while 31 sequences formed a unique cluster. The RSVA and RSVB glycoprotein gene sequences exhibited N- and O- glycosylation and selection pressure at several sites. RSV B exhibited slightly higher (0.042) nucleotide diversity per site (π) as compared to RSVA (0.019). ConclusionsOur results suggest that RSVA and RSVB strains in Pakistan exhibit distinct genotypic clusters and differ in their estimated tMRCA. Additionally, both genotypes showed glycosylation and selection pressure at specific sites, with RSVB exhibiting higher nucleotide divergence per site (π), indicating its potential to undergo further evolutionary changes and adaptation. Overall, this study provides unique insights into RSV molecular epidemiology. The study may also help improve our understanding of RSV evolutionary changes and the emergence of new genotypes in different regions worldwide and within Pakistan.

Characterize the influences of hydraulic fracturing on preventing rock burst from the stress and vibration fields

The thick and hard roof (THR) is a significant factor that induces rock burst incidents. Traditional deep-hole blasting methods struggle to effectively relieve pressure for the high-level THR on a large scale. Although the horizontal staged hydraulic fracturing technology can crack high-level rock stratas, its impact on roof fracture still needs to be clarified, and there need to be more effective methods to evaluate its pressure relief effect. This paper conducted a comparative engineering test of local hydraulic fracturing pressure relief and load reduction on the working face to address this gap. The key layer theory and mine earthquake distribution were used to identify potential hazards of rock strata and the fracturing strata. Revealed the spatial and temporal evolution rules of microseisms induced by mining work, the failure mechanism of high-energy mine earthquakes, the evolution characteristics of source mechanical parameters, and the evolution characteristics of the stope stress field. The results indicate that after fracturing microseisms during mining presented exhibit a uniform distribution of high frequency and low energy. The fracture fragmentation of the roof rock was reduced, and the range of mining disturbance was minimized. High-energy mine earthquakes induced by mining are transferred to the goaf. Simultaneously, the corner frequency and stress decrease while the rupture radius and the shear component of the failure mechanism increase. The integrity of the THR is compromised, and fracture propagates and slips along the pre-crack. The roof of the working face experiences localized pressure, with decreased periodicity and intensity, reducing the overall static load level of the coal seam under the fracturing area. The research findings serve as a valuable reference for further investigations into the mechanism and risk assessment of hydraulic fracturing in preventing and controlling rock burst.

TBM Advanced Geological Prediction via Ellipsoidal Positioning Velocity Analysis

Traditional seismic wave-based tunnel advanced geological forecasting techniques are primarily designed for drill and blast method construction tunnels. However, given the fast excavation speed and limited prediction space in tunnel boring machine (TBM) construction tunnels, traditional methods have significant technical limitations. This study analyzes the characteristics of different types of TBM construction tunnels and, considering the practical construction conditions, identifies an effective observation system and data acquisition method. To address the challenges in advanced forecasting for TBM construction tunnels, a method of ellipsoid positioning velocity analysis, which takes into account the constraints of three-component data directions, is proposed. Based on the characteristics of the advanced forecasting observation system, this method compares the maximum values on the spatial isochronous ellipsoidal surface to determine the average velocity of the geological layer rays, thereby enabling accurate inversion of the spatial distribution ahead. Utilizing numerical simulation, a model for the advanced detection of typical unfavorable geological formations is established by obtaining the wave field response characteristics of seismic waves in three-dimensional space, and the velocity structure of the model is retrieved through this velocity analysis method. In the engineering example, the fracture property, water content, and weathering degree of the surrounding rock are predicted accurately.

BZIP Transcription Factor PavbZIP6 Regulates Anthocyanin Accumulation by Increasing Abscisic Acid in Sweet Cherry.

Basic leucine zipper (bZIP) transcription factors (TFs) play a crucial role in anthocyanin accumulation in plants. In addition to bZIP TFs, abscisic acid (ABA) increases anthocyanin biosynthesis. Therefore, this study aimed to investigate whether bZIP TFs are involved in ABA-induced anthocyanin accumulation in sweet cherry and elucidate the underlying molecular mechanisms. Specifically, the BLAST method was used to identify bZIP genes in sweet cherry. Additionally, we examined the expression of ABA- and anthocyanin-related genes in sweet cherry following the overexpression or knockdown of a bZIP candidate gene. In total, we identified 54 bZIP-encoding genes in the sweet cherry genome. Basic leucine zipper 6 (bZIP6) showed significantly increased expression, along with increased anthocyanin accumulation in sweet cherry. Additionally, yeast one-hybrid and dual-luciferase assays indicated that PavbZIP6 enhanced the expression of anthocyanin biosynthetic genes (PavDFR, PavANS, and PavUFGT), thereby increasing anthocyanin accumulation. Moreover, PavbZIP6 interacted directly with the PavBBX6 promoter, thereby regulating PavNCED1 to promote abscisic acid (ABA) synthesis and enhance anthocyanin accumulation in sweet cherry fruit. Conclusively, this study reveals a novel mechanism by which PavbZIP6 mediates anthocyanin biosynthesis in response to ABA and contributes to our understanding of the mechanism of bZIP genes in the regulation of anthocyanin biosynthesis in sweet cherry.

Parameter characterization of the PBM-DEM method in numerical simulation of shallow buried mine explosions

Abstract To investigate the impact of various parameters on the numerical simulation of shallow buried mine explosions through the particle explosion method and discrete element method, this paper adopts a coupled method of particle blast method and discrete element method, namely the PBM-DEM method, to simulate the response of AL-6XN stainless steel plate under shallow buried mine explosions. This article first combines the experimental results of Børvik to validate the precision of the PBM-DEM approach. Then, the influence of particle quantity, interaction parameters between sand particles, and interaction parameters between sand particles and plate on the outcomes of the numerical simulations are analyzed. The analysis reveals that as the quantity of explosive particles rises, the central displacement and maximum kinetic energy of the plate escalate. In contrast, these values decrease as the number of sand particles increases. The interaction parameters between sand particles have almost no effect on the numerical simulation results. The damping and stiffness parameters between the sand particles and the plate have a pronounced effect on the numerical simulation results, and the center displacement and peak kinetic energy of the plate rise as the damping and stiffness parameters between the sand particles and the plate increase.

Study on cracking mechanism and key parameters of roof in gob-side entry retaining by pre-split blasting roof in deep mine

Based on 7135 working face of Qidong Coal Mine, the cracking mechanism of pre-splitting of gob-side entry retaining by roof cutting and the key parameters of pre-splitting blasting are studied by means of theoretical analysis, numerical simulation, and on-site measurement. Under the same blasting conditions, the energy of shaped-charge blasting in the direction of shaped charge is much larger than that of non-shaped-charge blasting, and the cracks generated along the direction of shaped charge are longer than that of non-shaped-charge blasting. The key parameters of pre-splitting cracks are the hole spacing and charge length. The crack propagation law of two holes blasting at the same time with different blasting methods, different linear charge density, and different hole spacing is studied. It is obtained that the cracking effect of shaped-charge blasting with the same hole spacing is better than that of non-shaped-charge blasting, showing that it can form part-through cracks; Increasing the linear charge density can increase the crack distance, but also destroy the integrity of the retained rock mass. The key parameters of advanced pre-splitting blasting in engineering practice are put forward. Generally, the maximum hole spacing and the minimum charge length that can produce part-through cracks are selected. When the hole spacing is 600 mm and the charge length is 4 m, the crack propagation of roof and the stress change of anchor cable after blasting are measured, and the crack formation rate reaches 86% to 90% within the blasting depth of blasting hole, and the anchor cable is in a good stress state, which can effectively control the roof. The research results provide a theoretical basis for the parameter design of pre-splitting blasting cracking of gob-side entry retaining by roof cutting.

Study on pyroshock response of micro-satellite pyrotechnic cutter

When the micro-satellite panel is deployed in orbit, it needs to be unlocked by the pyrotechnic device. The high-amplitude pyroshock environment generated in the unlocking process is fatal to the sensitive components on the satellite. Therefore, accurate and quantitative analysis of the structural response caused by the explosion can better understood the transmission characteristics of pyroshock, so that effective isolation methods can be carried out. In this paper, the finite element model of the pyrotechnic cutter is established in LS-Dyna, and the explosive unlocking process of the pyrotechnic cutter is simulated by the Particle Blast Method (PBM). The whole motion process of the cutter from unlocking to cutting off the pretightening rod is obtained, the distribution of stress and the propagation law of pyroshock wave are extracted. The results show that before unlocking, the explosion shock is the main part of the pyroshock, while after unlocking, it is mainly caused by the prestress release of the pretightening rod and the impact of the cutter hitting the cutting board. Explosive shock is the main factor affecting the near-field pyroshock, while the far-field pyroshock is mainly affected by the impact. To verify the accuracy of the simulation, a unlock test of pyrotechnic cutter are performed, the acceleration response values of the main reference points are obtained, and the results show that the two results are in good agreement in time domain and frequency domain. Based on the study of the separation characteristics, some suggestions on the optimization of damping buffer are proposed here.

Phytoplasma Associated with White-backed Planthopper on Rice Plants in Sidrap Regency, South Sulawesi

South Sulawesi is one of the largest rice production centers in Indonesia. Several important diseases of rice plants, such as those caused by viruses and phytoplasmas, can be transmitted by insect vectors, especially leafhoppers and stem plant. Symptoms of diseases caused by viruses and phytoplasmas are quite diverse but visually similar and difficult to distinguish. This study aims to analyze the presence of phytoplasma associated with white-backed planthopper which are commonly found in rice plantations. The research method used is by conducting surveys and explorations of insect samples in six villages in Sidrap District. White-back planthoppers found on rice plantations showing symptoms of yellowing and stunted leaves were sampled for further analysis, including total DNA isolation of insects, standard PCR amplification for insect and Nested-PCR for phytoplasma identification, gene sequencing for both amplicons, and nucleotide analysis using BLAST method and Mega X program. The PCR with CO1 primer successfully amplified a 700 bp amplicon from insects, whereas nested-PCR using fP1/rP7 primers followed by m23SR/R16F2n amplified phytoplasma supposedly around 1800 bp and 1250 bp of 16S RNA gene, respectively. The DNA sequencing analysis results indicate that the insect samples were identified as 83% Sogatella vibix species based on homology percentage analysis using BLAST and Mega X Program. As for the phytoplasma, it leans more towards the 16SrI group or Candidatus phytoplasma asteris (Aster yellows phytoplasma) with a homology percentage of 99%.

Genome-wide screening and bioinformatics analysis of Cannabis sativa LecRLK gene family

Lectin receptor-like kinase(LecRLK) is a class of phytokinase with lectin conserved domain, which plays an important role in plant resistance to biological and abiotic stresses, as well as plant growth and development. Cannabis sativa is an important multi-purpose plant, widely used in food, textile, medicine, and other fields. Genome-wide screening and expression analysis of the LecRLK family of C. sativa were performed in this paper, so as to provide scientific reference for functional analysis of the LecRLK family of C. sativa. Based on BLAST and HMM methods, 93 LecRLKs were identified in the whole genome of C. sativa, including 69 G types, 23 L types, and one C types. Subsequently, a series of bioinformatics analyses were performed on the LecRLK family members, and the physicochemical properties of the protein of the LecRLK family members were initially revealed. The prediction of cis-acting elements of promoters in family members showed that family members were regulated by hormones and stress response. The expression analysis showed that some family members were highly expressed in the roots, which may participate in the process of stress resistance. Several members were highly expressed in female flowers and may be involved in female flower development. This study provides a theoretical basis for further study of LecRLK gene function. Meanwhile, the expression analysis screens candidate LecRLK members who may participate in the resistance of C. sativa, which provides a theoretical basis for the subsequent selection of C. sativa varieties against resistance.

Cryoprotective role of vacuum infused inulin on the quality of artichoke: Interactive effects of freezing, thawing and storage period

Freezing of artichoke is a promising alternative to storing it in brine and canning. The perishable vegetable was vacuum infused with inulin to improve freezing tolerance. Artichokes with and without inulin were frozen by static, air blast and individual quick freezing (IQF) methods and thawed by microwave, 25 °C and 4 °C temperature levels at each month of 6-months storage. Process conditions were evaluated by multivariate analysis of variance (MANOVA) and were found significant on the quality parameters. Inulin infusion better conserved the aw, color, texture, ascorbic acid and overall integrity of artichokes during frozen storage. Inulin incorporation and IQF showed mutual positive effect on drip loss. Polyphenol oxidase (PPO) activity values fitted to 2nd order kinetic and the highest residuals were determined in static freezing. PPO showed alleviating effect on total phenolic content. Vacuum impregnation caused a color difference prior to freezing, but was found effective for maintaining color during storage. As a result, the use of quick freezing techniques together with the addition of cryoprotectant was effective in the preservation of artichoke quality attributes during frozen storage.

A Visual Survey of Tunnel Boring Machine (TBM) Performance in Tunneling Excavation: Mainstream Direction, Brief Review and Future Prospects

This study employs scientometric analysis to investigate the current trajectory of research on tunnel boring machine (TBM) performance and collaborative efforts. Utilizing software tools like Pajek 5.16 and VOSviewer 1.6.18, it scrutinizes literature from 2000 to 2021 sourced from the Web of Science (WOS). The findings illuminate TBM research as an interdisciplinary and intersectoral field attracting increasing national and institutional attention. Notable contributions from China, Iran, the United States, Turkey, and Australia underscore the global significance of TBM research. The recent upsurge in annual publications, primarily driven by Chinese research initiatives, reflects a renewed vigor in TBM exploration. Additionally, the paper presents a succinct evaluation of TBM advantages and drawbacks compared to conventional drill and blast methods, discussing key considerations in excavation methodology selection. Moreover, the study comprehensively reviews TBM performance prediction models, categorizing them into theoretical, empirical, and artificial intelligence-driven approaches. Finally, rooted in metaverse theory, the discourse delves into the immersive learning model and the architecture of a TBM metaverse. In the future, the immersive training and learning model diagram can be employed in scenarios such as employee training and the promotion of safety knowledge. Additionally, the TBM metaverse architecture can simulate, monitor, diagnose, predict, and control the organization, management, and service processes and behaviors of TBMs. This will enhance efficient collaboration across various aspects of the project production cycle. This forward-looking perspective anticipates future trends in TBM technology, emphasizing societal impact and enhancement of economic benefits.

Research on carbon emission quantification and evaluation for prefabricated inverted arch construction in drill and blast tunnels

Drill and blast methods cannot meet the requirements of modern tunnel construction in terms of efficiency and carbon emissions. This study proposes a prefabricated inverted arch construction technology and carbon emission calculation method applicable to drill and blast tunnels. The carbon emissions during prefabricated inverted arch construction were calculated, and the carbon emission model for on-site transportation was optimized. The indirect impact of improved construction efficiency on carbon emissions was discussed, further refining the carbon emission evaluation system for drill and blast tunnels. The results show that (1) The new technology of prefabricated inverted arch significantly improves construction efficiency and has promising application prospects; (2) Carbon emissions during prefabricated inverted arch construction are 9051.67 tCO2eq less than those during cast-in-place construction, with a reduction of over 15%, mainly due to reduced cement and steel usage resulting from optimized arch structure; (3) Considering the limitations of material transportation due to tunnel excavation distance, the carbon emission model for on-site transportation is optimized, resulting in a reduction of 35%–56% in on-site transportation emissions; (4) Incorporating the indirect impact of improved construction efficiency on carbon emissions into the calculation model, this indirect effect accounts for approximately 70% of the total emission reduction achieved by the prefabricated inverted arch technology.

DSNetax: a deep learning species annotation method based on a deep-shallow parallel framework.

Microbial community analysis is an important field to study the composition and function of microbial communities. Microbial species annotation is crucial to revealing microorganisms' complex ecological functions in environmental, ecological and host interactions. Currently, widely used methods can suffer from issues such as inaccurate species-level annotations and time and memory constraints, and as sequencing technology advances and sequencing costs decline, microbial species annotation methods with higher quality classification effectiveness become critical. Therefore, we processed 16S rRNA gene sequences into k-mers sets and then used a trained DNABERT model to generate word vectors. We also design a parallel network structure consisting of deep and shallow modules to extract the semantic and detailed features of 16S rRNA gene sequences. Our method can accurately and rapidly classify bacterial sequences at the SILVA database's genus and species level. The database is characterized by long sequence length (1500 base pairs), multiple sequences (428,748 reads) and high similarity. The results show that our method has better performance. The technique is nearly 20% more accurate at the species level than the currently popular naive Bayes-dominated QIIME 2 annotation method, and the top-5 results at the species level differ from BLAST methods by <2%. In summary, our approach combines a multi-module deep learning approach that overcomes the limitations of existing methods, providing an efficient and accurate solution for microbial species labeling and more reliable data support for microbiology research and application.

Dynamic Expressions of Yellow Stripe-Like (YSL) Genes During Pod Development Shed Light on Associations with Iron Distribution in Phaseolus vulgaris.

The global prevalence of iron deficiency-induced "hidden hunger" highlights a critical health concern, underscoring the pressing need to improve iron nutrition through safe and efficient means, such as increasing iron intake from plant-based foods. Yellow Stripe-Like (YSL) genes play a crucial role in long-distance iron transport between source and sink tissues in plants. Here, we report on the analysis of YSL family genes in the common bean (Phaseolus vulgaris L.), an iron-rich legume crop. We identified 9 YSL genes in the common bean genome using BLAST and HMM methods. Gene duplication analysis revealed that PvYSL7a and PvYSL7b originated through tandem duplication events. Structural analysis noted an absence of conservative motifs in PvYSL3b and PvYSL7a, which led to distinct predicted 3D protein structures. Leveraging publicly available RNA-seq data from developing bean pods, the expression patterns of PvYSL genes alongside pod and seed development were analyzed. Notably, PvYSL7a and PvYSL7b, as well as PvYSL1a and PvYSL1b, exhibited diverged expression patterns in seeds, signifying their functional divergence in this tissue. Moreover, PvYSL3a and PvYSL3b exhibited divergent expression patterns in both pod walls and seeds during pod development, underscoring their distinct roles in facilitating iron transportation between pods and seeds. This study provides valuable insights into the gene regulatory basis of iron accumulation in bean pods and seeds.

Study of BP and RBF Neural Networks Applied to the Prediction of Vibration Characteristics in Static Blasting of Dry Ice Powder

The novel dry ice powder static blasting rock breaking lacked working standards, especially for the vibration safety assessment of the construction site for the protection of the building structure, in comparison with the traditional drill and blast method which had a proven operational process and safety specifications. The Sadovsky vibration velocity prediction formula could only predict the vibration velocity and was project specific. Oscillation parameters that needed to be considered in the vibration safety assessment, such as the dominant frequency of vibration, could not be obtained through empirical formulas. Using the five parameters of hole depth, blast center distance, dry ice powder mass and rock classification as the main influencing factors, BP and RBF neural network models were constructed by Matlab software to predict the peak vibration velocity, main frequency and maximum displacement of dry ice powder blasting. Projection results revealed that it is structurally simpler than the BP neural network and that the RBF was more accurate in predicting the target than the BP network. The results of the study had significant implications for the safe application of the new technology, and more samples of field data need to be obtained in the future, along with the use of more advanced predictive modelling.

Assessing Long-Term Excavation Damage in Switzerland’s Bedretto Adit: A Field Investigation in the Northern Section

The Bedretto adit, in the Alps of Switzerland, was excavated in 1972–1982 as an auxiliary adit for the main Furka Base Tunnel. The adit is 5218 m long, being excavated mostly in the Rotondo Granite with drill and blast methods to create a horseshoe cross-section. Much of the tunnel has remained unlined and such long observation periods are seldom available since tunnels typically are lined shortly after construction and mines are often closed or backfilled. Previous research in 2004 characterized the depth of failure (DoF) around the adit and found on average a depth of 1.1 ± 0.03 m. A site investigation was carried out in 2017, aimed to measure the DoF through 3D light detection and ranging scanned sections again. The new 3D scans covered a longer section of the tunnel with each scan, up to 6 m in length, compared to the previous laser scans with a single circumferential pass. The results were compared with the data from 2004 and with empirical and numerical prediction curves for Excavation Damage Zone depths. The findings indicate that between 2004 and 2017, the measured DoF generally extended, on average, by 0.1 m, implying that failure has progressed with time. Furthermore, the analysis showed that the volume of failure from 2004 extended up to 1.9 m3/m, and this volume increased to 3.2 m3/m in 2017 on average. The VoF was used as a means to overcome the challenge of comparing past to present scan results, since the exact location of the 2004 measurements were not known. Significant variations in the measured DoF at sections of the adit near faults and below a glacier indicate that these external factors can significantly influence the rock mass behaviour. When comparing the DoF to empirical excavation damage zone prediction intervals, the level of damage at the Bedretto adit is comparable with the outer excavation damage zone. This is a region of isolated micro-cracking, and it conceptually suggests that the continued spalling in the Bedretto adit is the results of crack propagation from initial excavation induced damage that leads to interaction even after 41 years since excavation works ceased.

Investigating the Impact of Short Burden and Spacing on Blasting Output in Zeberced Quarry

Blasting has been adjudged as the cheapest method of hard rock fragmentation. The itinerary of rock breakage through blasting in open pit mines is a complex portent which is measured via various variables and parameters. This research investigates the impact of short burden and spacing on blasting output with the aim of establishing a more suitable and economically viable approach. Trials and proposed methods were adopted to investigate blasting geometry results. Results obtained showed that the trials method of 1.2 m by 1.2 m and proposed blasts method of 2.0 m by 2.0 m burden and spacing at 9m depth, covered areas were 80.64 m2 and 99.36 m2 respectively, while at 12 m depth with same blasting geometry covered 224 m2 and 276 m2 respectively. The first trial and proposed blasts methods using burden and spacing of 1.2 m by 1.2 m produced 2,583.71 tons and 2,387.62 tons respectively. Hence, with the use of 2.0 m by 2.0 m burden and spacing, the blasts operations produced 7,176.96 tons and 6,632.28 tons respectively. Meanwhile, the results revealed that, short burden (≤ 1.2 m by 1.2 m) threatens safety in which flyrocks are spawned and it’s dangerous to equipment and personnel, at the same time, the areas covered, quantity produced (i.e. volume) and the tonnage were small compared to the engineering control methods. However, it was found that the trials blast methods were not economically worthwhile in terms of explosive consumption compared to the proposed measure of the geometry.