The aim of this work is to investigate the relationship between the dewatering measures and the condition of the track quality and whether dewatering affect the degradation rate of the track. The goal is to find out if the dewatering of the substructure gives a better track quality condition and a slower track degradation. The literature study performed in this work shows that there is no research done that demonstrates the relationship between dewatering and track quality degradation.

This work comprise a case study of railway lines where dewatering has been performed compared to sections with the same properties were dewatering was not performed. The work is limited to the track section 113 and 124, and to investigation of the height deviation of the track. The Swedish Transport Administration, Trafikverket, has made data available from the database OPTRAM which is used in the analysis. Three different wave length were analysed; short-wave (1-25 m), medium-wave (25-70 m) and long-wave (70-150 m). This is a quantitative study limited to literary studies, data collection, data quality assessment and data analysis. The results have been analysed by means of literature studies including newly published results from this field.

The dewatering measures gives following effects in the studied wavelengths:

• The dewatering impact on the track quality in all wavelengths.
• The dewatering initially impairs track quality in the short-wave which may be caused due to settlements in the substructure.
• The track quality in the medium-wave show an improvement of the track quality, which are statistical confidentially.
• The track quality in the long-wave show a marginal changes after the dewatering.
• The degradation rate of the track quality for the medium-wave will be lower after dewatering, which applies to both the time and tonnage domain.
• To compensate the change in the track quality after dewatering for the short-wave the recommendation is to tamp the track after dewatering.

This study shows that dewatering of the substructure followed by tamping is a good maintenance action to improve the track quality in the long-time run. Today Trafikverket primarily use the short-wave to initiate the maintenance activity tamping, however it is a point to look more even on the medium-wave to get a more holistic view of the track quality and its degradation.

Further work could be to analyse more number of sections that had have problems with track quality and were no tamping is done before dewatering but could have been done in combination with dewatering. Tamping can have been performed after one or a couple of year after dewatering. Moreover, further work could be to develop a cost model for dewatering in a lifecycle perspective.

Design of sub-level blasting rounds and optimisation has become more important now when the sizes of the blasting rings get larger. Sufficient fragmentation is one of the key factors, and in confined blasting as in sub-level caving, this influences the mobilisation of the blasted ring. Model scale tests have been made to understand the mechanisms of rock breakage and therefore fragmentation under relatively confined conditions. By using the acoustic impedance between the blasted material and the confining debris, a relationship for fragmentation has been found depending on material, specific charge (powder factor) and physical properties of the debris. The results can be comparable with confined blasting in large scale.

Sub-level caving (SLC) is classified as a mass mining method and there is increasing interest in its application world wide and under a very wide range of geotechnical environments. In terms of flow, the caved rock or debris at the interface first acts as a wave trap, which may reduce the fragmentation. Model scale tests are being made to understand the mechanisms of rock breakage and therefore fragmentation under relatively confined conditions. To minimize geometrical and geological effects, tests were conducted mainly on cylinders of magnetic mortar of size Ø140×280 mm and PETN cord with different strengths was used as explosive in a center hole, giving a specific charge between 0,2 and 2,6 kg/m3. The size distributions of the blasted material and the aggregate as well as the swelling of the cylinders have been measured. For the latter, a freezing-slicing method was developed. The results show that the confinement results in fragmentation being coarser when compared to that from free cylinders, and that the properties of the debris have a strong influence on the fragmentation and the swelling.

Sub-Level Caving (SLC) is an important mass mining method, involving blasting of ore against granular material in the form of caving debris. The debris compaction due to blasting influences the caving process. Blasting tests were made on cylinders of magnetic mortar placed inside plastic cylinders and confined by packed granular material. By introducing the acoustic impedance between the mortar and the confining granular material, the compaction is found to depend on material, specific charge and physical properties of the debris with statistical analysis. The tests have shown to be a good input for numerical modelling of blast compaction.

Mosul Dam, located on the Tigris River north of Iraq, is experiencing sedimentation problems, especially near the Al-Jazeera pumping station that supplies the irrigation water for the Al-Jazeera project. The sources of the sediment accumulated within the reservoir are from the Tigris River, as well as ten side valleys on both sides of the reservoir. The sediment inflow rate into the reservoir and the released values are considered on the basis of the operation schedule of the dam for the considered period from 1986 to 2011. The sediment loads were estimated on the basis of available measurements and estimated literature values. The HEC-RAS 4.1 model was used for flows and sediments in the main river and  reservoir. The model was calibrated for flow simulations (coefficient of determination r2 = 0.87) and sediment routing based on bed level, (with resultant r2 = 0.98 and Mean Absolute Deviation of 0.95). The Ackers–White equation was used in the HEC-RAS model for sediment routing because of the wide range of sediment sizes in the study case. The resultant total accumulated sediment load volume was 1.13 km3, a value that is very close to the measured values (1.143 km3) obtained from a previous bathymetric survey. Furthermore, the model indicated most of the sediment (80.7%) was deposited during the first five of the dam operation.

I denna artikel redovisas nyare litteratur om sprängningens påverkan nedströms i sönderdelningsprocessen. Först presenteras en internationellt använd sprängningsmodelloch vilka slutsatser man kan dra av hur styckefallet påverkas av förändringar i sprängningen. Därefter presenteras laboratorie- och fältundersökningar av hur sprängningenpåverkar mikrosprickinnehållet i och kross- och malbarheten hos sprängda bergstycken. Sedan refereras allmänna fältstudier på kross- och kvarnsystem och undersökningar därvärdet av ökat utbyte till följd av ändrad sprängteknik beräknas. Systemansatser som Mine-to-mill redovisas.

Artikeln avslutas med några slutsatser om sprängningens inverkan på förhållandena nedströms. Huvudslutsatsen blir att sprängningen sannolikt har stor potential att förbättra utbytet i sönderdelningsprocessen men att förbättringarna kan vara svåra att uppnå på grund av systemens komplexitet. Undersökningar pekar på att de mikrosprickor som sprängningen skapar kan överleva tills flödet når kvarnarna men det finns svaga direkta bevis för det. Sprängningens inverkan på friläggning av malmpartiklar är också oklar.

Fragmentation results for model- and full-scale blasts in three different rock materials are presented. The model-scale blasts were conducted in Ø100-300 mm cylindrical specimens charged with PETN. The full-scale Bårarp and Hengl bench rounds consisted of a single row of 5-10 holes, the Vändle rounds of multiple rows. The Bårarp rock mass consists of massive, damage free granitic gneiss whereas the other rock masses were both jointed and blast damaged. In all cases production explosives were used.There are three major likenesses in the fragmentation. Firstly all the sieving curves can be accurately described by the Swebrec function. Secondly, in the fines range the curves shift upward in parallel in a log-log diagram when the specific charge increases, in accordance with one of the NBC precepts. Thirdly, the sets of sieving curves for one rock all seem to have an inflection point at the same x-value in the log-log diagram. This point varies; from about 0.5 mm for the Hengl amphibolite, to 1.0 mm for the Bårarp gneiss, and 1.5 mm for the Vändle granite. Taken together these likenesses strongly suggest that the breakage mechanisms in model- and full-scale have strong similarities, despite the very different conditions.The model- and full-scale fragmentation also differs in important aspects. Firstly the definition of specific charge q is based on different volumes related to the actual breakage and the presence of free faces, which are shown to influence the fragmentation. Further the exponent for how the average fragment size x50 decays with increasing q is larger in model-scale, about 1.1 (x50∝1/q1.1) as opposed to 0.8 in full-scale. Further, the influence of size, given by the charge size Q1/6 in the Kuz-Ram model doesn't fully explain the observed x50 differences when q is constant. The rock factor A also seems to have a size dependence built in, which leads to different results for the Vändle and Bårarp tests. There is further a difference in the slope values s50 at x50 between model- and full-scale blasting. The values follow a previously established experimental relationship quite well. Thus the undulation exponent in the Swebrec function may be expressed as a function of the other two parameters, x50 and xmax. In order to revise the size dependence expressed by the Kuz-Ram equation, which in the case of x50 apparently involves not only Q, but also A and the exponent of the specific charge, it will probably be necessary to broaden the specific charge concept.

The Boliden Mineral's Aitik mine strives to increase the throughput of the primary mills, which requires a better understanding of the blast fragmentation. This article describes detailed fragmentation monitoring work of round, 4141-2. Structural mapping and core drilling, drilling and charging monitoring, VOD-measurements and blast filming were made. The blast fragmentation on the trucks was monitored automatically with Split Online and manually with Split Desktop. Four barrel samples were sieved to obtain the fines part of the fragment size distribution. The Desktop images had to be edited to avoid fragment splitting and merging errors. The Online images contained errors of many kinds and seem to be sensitive to light conditions; measured fragmentation during night-time was about 50% finer than during daytime. The data appear to be log-normally distributed. The average fragment size x50 became either 171±108 mm (Online) or 458±175 mm (Desktop) and the correlation between the online and desktop data is virtually non-existent. Suggestions are also made how to improve the quality of the data. At the end, a complete fragment size distribution down to 0,2 mm for round 4141-2 is constructed by the use of the x50- and x80-values from Split Online and Desktop and the sieved samples, using the Swebrec function.

The blasting at the Vändle aggregate quarry has been investigated in order to predict the effect of the specific charge on fragmentation and to assess the contribution of blasting and primary crushing to the -32 mm fines. Two 25000 ton blasts divided into halves were monitored. Each half had an expanded or a shrunken pattern in order to lower or raise the specific charge. A normal round uses Ø90 mm drill-holes on a 34 m pattern with a gassed bulk emulsion blend with 20-25 % of AN prills. The test rounds lay directly behind each other, with a shrunken pattern behind an expanded one and vice versa to minimize the influence of geology.From the muck piles, four test piles of about 500 tons were extracted and photographed for image processing. About a quarter of each was sieved in four steps and fines samples taken. The material was replaced and the whole pile fed to the primary crusher while measuring the effect and the fines produced. Crushability and grindability data were measured.All lab samples and crushing test samples follow the new Swebrec distribution extremely well. The fragmentation size distribution of the muck piles is constructed using the sieving data and the lab samples, conforming to the Swebrec function. Image analysis gives a fragmentation curve with a distinctly different character. Of the total of 28 % of -32 mm fines after primary crushing, blasting and crushing contribute about half each. Based on these data a set of design curves are constructed that allow the prediction of how any given fraction changes when the specific charge in the round is changed.

Sprängförsök har utförts vid Swerock AB:s Vändletäkt för att ta fram en beskrivning av hur sprängningsresultatet kan påverkas så att önskat styckefall in i förkrossen erhålls. Resultatet blev bl a designkurvor som beskriver hur styckefallsfördelningen ändras när den specifika laddningen ändras. I två produktionssalvor krymptes hålmönstret i ena halvan och glesades ut i den andra med användning av befintlig borrutrustning. Uppföljningen bestod av profil- och hålinmätning, mätning av laddad mängd och VOD samt styckefallsmätningar mm. Ur salvorna togs fyra provhögar och ca 100 ton ur varje siktades och utvärderades med bildanalys. Materialet lades sedan tillbaka och provhögarna krossades medan krossningsenergin mättes. Ur siktdata kunde styckefalls-fördelningarna konstrueras med hjälp av Swebrecfunktionen. Några slutsatser är att - Styckefallet liknar bergmaterialkurva nr 62 - Sprängningen och förkrossen bidrar med lika mycket var av producerad bärlagerfraktion - Skutandelen kan uppskattas med bildanalysen men styckefallskurvorna från bildanalysen har annan form än siktkurvorna - Siktkurvorna bedöms vara tillförlitligare

Blasting is a cost-effective process for the mining and construction industryfor production and development. However, blast vibration is an undesired side effect of the process. Itmight causesevere damagesto the surrounding buildings and infrastructures. Depending on the type of the blast, location and design of a blast, the magnitude of peak particle velocity (PPV) needs to be lower than threshold as stated by local regulations. This study investigated if there is a difference between confined and free face blasting. The experimental plan was composed of 10 decoupled confined holes and 13 decoupled free face holes. All the blastholes were charged withapproximately0.95kg (2.09 lb/stick) of dynamitestickexplosive (Minex eco Ø32 mm(1.26 in)) and blasted separately. The instrumentation was composedby four triaxial grouted geophones that were used to capture the emanating waves from the detonation of the blastholes. The waveforms were analyzed in a conventional way, i.e. calculation of PPV and frequencies. In addition to the PPV analysis, a continuous wavelet transform (CWT), the analytic Morlet wavelet, was also applied to analyze the waveformsin terms of frequency componentsfrom the detonation of the blastholes. The results of the analysis did not show any significant difference between the free face and confined blastholes. 

The optimization of the explosive performance is of great importance since blasting is extensively usedin civil projects and mining industry. An improved understanding of how the energy from thedetonation of an explosive is transmitted to the surrounding rock mass is critical information for theproper selection of an explosive. Therefore, an extensive study was done on the influence of theblasthole diameter on the Velocity of Detonation (VoD) and the detonation front curvature. In thisstudy, pure emulsion was tested in confined conditions to better simulate the behavior of the detonationof the explosive in rock mass conditions. A methodology is proposed for carrying out the evaluationof the explosive performance. The blasthole diameter of the samples varied from Ø 25 mm (0.98 in)up to Ø 65 mm (2.55 in). The confiner was a magnetic mortar cylindrical sample with mechanicalproperties similar to a rock mass. A streak camera and VoD probes were used to measure detonationfront curvature and VoD. The data was analyzed and correlated with the physical parameters of theexplosive. Additional to this, the data was further used to calibrate numerical models in LS-Dyna.