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[en] Shallow seismic reflection method is used to for research of mine, fault and stratigraphy and these researches have been result successfully. Survey parameters should be determined with detailed pre-research before data collection. In this study, limestone-fly sch discontinuity experienced at surface and its extension was researched with collected reflection data
[en] Multi-model frameworks are widely used to identify the appropriate model structure for the study catchment. However, most frameworks mainly consider the process complexity of the model, and few of them consider the spatial complexity. In this paper, we investigated the appropriate model structure for a karst catchment from the aspect of spatial complexity. The purpose is twofold: (1) to investigate whether the spatial complexity is needed to simulate the spring discharge of this karst catchment and (2) to investigate whether the increase of model’s spatial complexity can make up its deficiency on the process complexity. Three simple lumped models with different process complexities were chosen to gradually increase the spatial heterogeneity of their parameters to investigate the appropriate model structure for simulating the discharge of a karst spring. The results show that the performances of three lumped models highly improve when adding the routing function to them. However, further considering the spatial parameter heterogeneity, only one model shows obvious performance improvement and other two models show limited improvement. Moreover, this model with relatively complex spatial parameter heterogeneity still shows worse performance than another lumped model. This indicates an increase of models’ spatial complexity cannot always make up their process deficiencies. The final comparison results indicated that the lumped model or their semi-lumped version with flexible process complexity is enough to simulate the discharge of this karst spring and no extra spatial complexity is needed. Our studies also indicated that the increase in spatial complexity of the model cannot always fully compensate its deficiency in process complexity.
[en] Although researchers have realized varying degrees of success in small-scale physical in situ testing, most will agree that the greatest uncertainty stems from the uncontrollable field variables. Given the diverse nature of field conditions encountered, there exists no reliable and proven method of predicting fragmentation. Due to the lack of adequate field controls, it is unlikely that a universal physical model will ever be developed for all blasting. This paper presents the results of a test conducted at the Hadjar Essoud quarry to investigate the problems associated with the discontinuities in the rock, which are among the factors causing the reduction of the resistance of the rocks to the explosive. Nevertheless, the distance between the joints, their dip and strike, and the position of the detonator play a significant role in the final fragmentation of the rock. In this work, we studied the role of the abovementioned factors on models of limestone rock of 150 X 375 X 450 mm. Accurate measurement of blast, fragmentation is important in mining and quarrying operations, in monitoring blasts, and optimizing their design. We shall use the Kuznetsov-Rammler method to measure fragmentation. It shows great potential as a practical aid to predict and control the quality of the fragmented material in the Hadjar Essoud quarry. (author)
[en] This paper reports on horizontal drilling in the Giddings field Austin chalk which has significantly improved average well recoveries and more than offset increased drilling costs. Although not the panacea originally promoted, horizontal drilling, in Giddings field, offers economic profits to the average investor. Economic analysis indicates that the typical investor is making money by earning returns in excess of market values. Field-wide development will, therefore, remain active unless oil prices or average well recoveries fall below $12/bbl or 112,000 bbl of oil equivalent (BOE), respectively. The application of technological innovation in the Giddings field may culminate in the drilling of over 2,000 horizontal Austin chalk wells, and has conceivably increased recoverable reserves by 400 million BOE
[en] In this study uniaxial cyclic loading tests were performed on Cheon-Ho Mt. Limestone specimens to investigate the fatigue failure behavior. The loading rate was kept constantly at 760kg/cm2/sec under cyclic loading. In order to reveal the fatigue behavior for each rock type, the test results were mutually compared with previous studies carried out on Indiana Limestone and Seong-Ju Sandstone. Fatigue data is presented in the form of S-N curves, which illustrate the relationship of maximum applied stress(S) to the number of cycles(N) required to produce failure. For the purpose of comparing the S-N curves for each rock type, the test data were formulated up to 104 cycles and the correlation coefficients(R) on Cheon-Ho Mt. Limestone and Seongju Sandstone specimen are 0.886 and 0.983, respectively. All three rock specimens were found to have shorter fatigue life at higher applied stress levels. The fatigue life for each rock type was considered as no less than 81.5, 70 and 74.8%, for Cheon-Ho Mt. Limestone, Indiana Limestone and Seong-Ju Sandstone, respectively. The comparison in static strength for monotonic loaded specimens and specimens which did not fail even after 104 cycles indicated that the increasing rate of strength was about 6.18 and 10.96%, for Cheon-Ho Mt. Limestone and Indiana Limestone, respectively. Poisson's ratio and volumetric strain for Cheon-Ho Mt. Limestone and Seong-Ju Sandstone, tended in all the cases to rapidly increase at higher stress levels and with an increase in number of cycles. This increasing trend becomes rapid and obvious just before failure. Also Poisson's ratio and volumetric strain for each stress level were compared and the first cycle and the cycle prior to failure. (Author)
[en] The lithological features of the ore-bearing siliceous rock and limestone are analysed in detail of the uranium metallogenic belt in the western Qinling. The types of siliceous rock, limestone and their intermediate type and the lithogenesis evolution are discussed. The paper proposes that the intermediate type of siliceous rock and limestone is the most favourable ore-bearing rock in the metallogenic belt
[en] An investigation of the stress-strain behaviour of Cobourg limestone has been conducted through the testing of 54 Uniaxial Compressive Strength (UCS) and 47 Brazilian Tensile Strength (BTS) specimens. The rock for these tests has been collected from St. Mary's Quarry located in Bowmanville, Ontario. At this site the unit is alternatively referred to as Cobourg or the Lindsay Formation. This rock presents core scale heterogeneity in the form of large (50-75 mm) calcite rich nodules surrounded by more clay rich lenses. Specimens have been prepared with a length to diameter (L/D) ratio of 2.5 for UCS testing and a thickness to diameter (t/D) ratio of 0.5 for BTS testing. The influence of specimen water content and scale was studied for both UCS and BTS specimens, to investigate the elastic and strength properties of the rock. In addition, UCS specimens have been tested with varying axial strain rates to examine the effect of loading rate on the Cobourg limestone. Oven drying as well as a number of saturation methods were used and compared in this study to investigate the efficiency of saturation and the impacts on the sample. The samples were saturated with synthetic formation pore water (SPW). Long term saturation by immersion (one to three months) is not efficient in increasing the level of saturation and, due to the unconfined nature of the sample while immersed, imparts non-realistic damage to the sample that is not representative of in situ saturation. Vacuum saturation did not prove markedly more effective than simple immersion over the same time frame (one week). One-week submersion effectively demonstrated the influence of resaturation and represents the most optimal resaturation time period for future investigations. However, due to the challenges of resaturating such low porosity rock, sample encapsulation after extraction is recommended for geomechanical testing. For the purposes of comparison, 0.25% water content is taken as a datum corresponding to 'Room Relative Humidity' (RRH). Average strength thresholds for three 76 mm diameter samples at 0.25% water content and standard loading rates for UCS, CD and CI are 107MPa, 85 MPa and 46 MPa respectively. Based on testing results, maximum achievable saturation was shown to decrease UCS by up to 14% compared to room relative humidity conditions (RRH) and Critical Damage (CD) by up to 15%. CI was reduced by a more modest 8%. Oven drying to 0.065% water content, on the other hand, increased the three thresholds by 24%, 26% and 13% respectively. BTS was reduced by up to 25% by saturation and increased by up to 20% by drying. Scale effect was investigated through the testing of four different core specimen sizes (50, 76,101 and 126 mm diameter). Young's modulus of the rock was seen to increase with increasing specimen diameter within the range of sizes tests. There has been no clear influence of scale on Poisson's ratio, CI, CD, or UCS of the Cobourg limestone. The BTS results have shown a decrease in strength with increasing specimen diameter with most of the decrease occurring between 50 and 76 mm. The results of loading rate testing on Room Relative Humidity (RRH) and one-month saturated specimens have shown no significant effects to changing axial strain rate with respect to Young's modulus, Poisson's ratio, and CI threshold of the rock. The RRH specimen results show a moderate decrease in CD and UCS threshold with increasing axial strain rate, while one-month saturated specimens the opposite trend. (author)
[en] The MTT (Mean Transit Time) of a catchment without significant surface flow is normally taken to be the sum of mean residence time in the unsaturated zone and mean residence time in the saturated zone. However, the Chalk is a multi-porosity limestone aquifer, with a microporous matrix. This means that the movement of water through the Chalk can occur in complex ways, making the prediction of MTT far from straightforward. Although the Chalk is a regionally-important aquifer, no study of catchment MTT has yet been published. The present study is based on the catchment of the River Lambourn in Berkshire, UK, with an area of 235 km2. Interfluve areas rarely rise above 200 m asl (above sea level), whereas river elevation at the foot of the catchment is ∼50 m asl. Mean annual precipitation is 731 mm. The thickness of the Chalk unsaturated zone reaches a maximum of over 100 m at the water divide at the top of the escarpment on the northern flank of the catchment.