Introduction: A ‘soft-rock’ petroleum-type approach to exploration for ‘hard-rock’ minerals in sedimentary basins

2000 ◽  
pp. 1-12
Author(s):  
D. Taylor
Keyword(s):  
Hard Rock ◽  
Soft Rock ◽  
Sedimentary Basins ◽  
Rock Minerals

scholarly journals Calculation Method of Overburden Damage Height Based on Fracture Mechanics Analysis of Soft and Hard Rock Layers

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Liang Chen ◽  
Shaowu Fan ◽  
Can Zhao ◽  
Lang Zhang ◽  
Zhiheng Cheng
Keyword(s):  
Fracture Mechanics ◽  
Coal Seam ◽  
Calculation Method ◽  
Hard Rock ◽  
Soft Rock ◽  
Mining Area ◽  
Overburden Rock ◽  
Rock Interaction ◽  
Mechanics Analysis ◽  
Seam Mining

Under the geological condition of soft and hard rock interaction stratum, the overburden damage height can provide a quantitative support for the design of the locations of gas drainage boreholes in the roof mining fracture zone and the determination of the hydraulic fracture zone in coal seam mining. The interbedded structure of overlying mud rock and sandstone in the Lu’an mining area in Shanxi is a typical soft and hard rock interaction stratum. In view of the lack of soft rock fracture mechanics analysis and the improper calculation of the damage height of overburden rock caused by constant rock residual bulking coefficient to be used regularly in the analysis, in this paper, we constructed a fracture model of soft and hard strata by giving a quantitative classification criterion of soft and hard rocks and introducing a fracture failure criterion of soft rock strata and the space constraint condition of broken-expansion rock formation. Aiming at improving the calculation precision of overburden damage height, we presented a calculation method based on fracture mechanics analysis of soft and hard strata, which could delineate the extent of intact rock in overlying strata from bottom to top to determine the damage height of overburden rock. This research took Yuwu coal mine in Lu’an mining area as an example. Results showed that (1) by the calculation method, the overburden damage height of the N1102 fully mechanized caving face in Yuwu coal mine was 51.44 m, which was less than the value obtained by an actual borehole TV method as well as the numerical simulation result of 53.46 m, with a calculation accuracy about 96.22%, which is quite high for both. The calculation accuracy of the proposed method was higher than that of the three conventional theoretical methods, and it effectively solved the limitation of the fracture analysis method without the inclusion of the soft rock layer in design and the distortion problem due to the residual bulking coefficient to be improperly used in simulation. (2) There was no noticeable fractures in the broken soft rock zone, and the whole fractures were mainly low-angle rupture; the fractures in hard rock layer had obvious ruptures and multiangle cracks, and the average fracture width of soft rock was 2.8 mm smaller than that of hard rock. The fracture modes of soft rock and hard rock were mainly tensile failure and tensile shear failure, which verified the correctness of the fracture mechanics model of soft and hard rock layers constructed in this paper. (3) It is noticed that the tensile strength of rock in this method needs to be obtained through rock mechanics experiment on overlying strata in the study area, and our proposed method was applicable to the mining conditions of near horizontal coal seam. The calculation accuracy of this method meets the engineering error requirements and can be applied to the prediction of overburden damage height in near horizontal coal seam mining.

scholarly journals A New Evaluation Method for the Uniaxial Compressive Strength ahead of the Tunnel Face Based on the Driving Data and Specification Parameters of TBM

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Yuexiu Wu ◽  
Chishuai Ma ◽  
Xianjun Tan ◽  
Dianseng Yang ◽  
Hongming Tian ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Uniaxial Compressive Strength ◽  
Evaluation Method ◽  
Hard Rock ◽  
Rock Type ◽  
Soft Rock ◽  
Tunnel Face ◽  
Diversion Tunnel ◽  
Proposed Model ◽  
High Prediction

Uniaxial compressive strength (UCS) is a very important fundamental mechanical parameter for TBM construction. In this work, a predictive model of UCS was proposed according to the TBM parameters including torque, penetration, cutter number, and cutter diameter. The parameter of the new proposed model was established by fourteen existed TBM tunnels’ construction data. To describe the relationships of UCS with PLSI of the Murree tertiary hard rocks, regression analyses have been conducted and a fitting equation with high-prediction performance was developed. Validation from the data of Neelum–Jhelum (NJ) TBM diversion tunnel were carried out. The absolute errors between predictive UCS and experimental UCS were presented. Through comparison, it can be concluded that the proposed calculation equation of UCS has a high accuracy for a certain rock type with UCS from 50 MPa to 200 MPa. For special hard rock or soft rock, a new calculation equation between UCS and TBM parameters should be studied furthermore.

scholarly journals Analysis of Soil Categories on Seismograf Sensor in Java Island Based on Ground Predominant Period and Vs30

2015 ◽  
Vol 5 (02) ◽  
pp. 34
Author(s):  
Nugroho Budi Wibowo ◽  
Dian Susri Nurhaci
Keyword(s):  
Hard Rock ◽  
Soft Rock ◽  
Processing Method ◽  
Soil Conditions ◽  
Rock Weathering ◽  
European Research ◽  
Predominant Period ◽  
Data Processing Method ◽  
Weathering Process ◽  
Stiff Soil

<p>The aim of this research is to analyze the categorization of soil at sensor site locations based on predominant period of the ground and Vs30. This study was conducted at nine sites seismograph sensors in Java and Madura. Data processing method is using HVSR (Horizontal to Vertical Ratio) based on the SESAME European research project. The Java and Madura Vs30’s data were obtained from the USGS. This study utilizes the criteria of JRA 1990 and BSSC 2000 were used to determine the soil categories. It is found that the criteria of JRA 1900 and BSSC 2000 satisfies some sites namely LEM, KMMI, UGM and WOJI. The site of LEM and UGM have a soil that can be categorized in C type (dense soil / sand to soft rock) with dense soil conditions to the rock weathering process. Site KMMI can be categorized in D type (stiff soil) with dense soil conditions. Whereas the site WOJI can be categorized in A + B type (Hard rock and firm to hard rock) with hard rock conditions.</p>

scholarly journals Classification of Red-Bed Rock Mass Structures and Slope Failure Modes in South China

Geosciences ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 273 ◽  
Author(s):  
Cuiying Zhou ◽  
Xu Yang ◽  
Yanhao Liang ◽  
Zichun Du ◽  
Zhen Liu ◽  
...  
Keyword(s):  
Rock Mass ◽  
South China ◽  
Slope Failure ◽  
Failure Modes ◽  
Hard Rock ◽  
Soft Rock ◽  
Red Beds ◽  
Rock Falls ◽  
Geological Formation ◽  
Red Bed

Red beds are Meso–Cenozoic continental sedimentary strata that are mainly composed of gravel stone, sandstone, siltstone, mudstone, and shale and occasionally have interlayers of limestone, halite, and gypsum. As a typical rock mass, red beds are widely distributed throughout South China. In a typical tropical and subtropical continental environment, red beds are the product of multiple sedimentary cycles, which have resulted in complicated rock mass structures that play an important role in rock mass stability. It is thus of great significance to investigate the influence of different rock mass structures on the stability of red-bed slopes. In this paper, the geological formation history of red beds in South China is described. The main features of red-bed rock mass slopes in South China are discussed. The main combinations of inner geomechanical structures comprise: (1) mega-thick soft rock structures; (2) mega-thick hard rock structures; (3) thick hard rock structures with weak intercalation; and (4) soft–hard interbedded structures. In addition, the features of slope failure are analyzed, and four common failure modes are identified from the statistical data: (a) weathering spalling and scouring; (b) rock falls; (c) landslides; and (d) tensile dumping.

Study on Eccentric Wear Mechanism of Pick-Shaped Cutter in Soft and Hard Interbedded Formation Tunnel

2014 ◽  
Vol 501-504 ◽  
pp. 1668-1671 ◽  
Author(s):  
Dong Peng Wu ◽  
Xin An Yang ◽  
Zhi Si He ◽  
Li Cao
Keyword(s):  
Hard Rock ◽  
Soft Rock ◽  
Tunnel Excavation ◽  
Cutting Resistance ◽  
Cutting Machine ◽  
Resistance Torque ◽  
Rotary Cutting ◽  
Homogeneous Formation ◽  
Rock Strata ◽  
Starting Torque

This paper analyzes the stress of the pick-shaped cutter of rotary cutting machine in process of tunnel excavation in soft and hard interbedded formation, results show that the resistance of pick is obviously jumping fluctuations comparing to that of homogeneous formation. When pick transits from cutting hard rock to soft rock, cutting resistance and driving resistance of pick decrease instantaneously, which leads to momentary decreasing of rotation torque. And mud ball is compacted by high impact force of rotary cutting machine when cutting hard rock strata, as a consequence, resistance torque increases. When the sum of resistance torque and starting torque is greater than rotation torque, pick can`t rotate, leading to eccentric wear of pick. At last, this paper puts forward several improvement suggestions.

Analysing of the Factors Affecting Pre-Stressing Losing in Pre-Stressing Cable Anchor and Recommending Compensative Measures

2011 ◽  
Vol 261-263 ◽  
pp. 1891-1897 ◽  
Author(s):  
Xun Guo Zhu
Keyword(s):  
Creep Deformation ◽  
Hard Rock ◽  
Steel Wire ◽  
Soft Rock ◽  
Soil Mass ◽  
Affecting Factors ◽  
Internal Factors ◽  
Rock Creep ◽  
Cable Bolt ◽  
Rock And Soil

After the rock bolt or cable bolt installed in rock and soil mass, as the time goes on, the pre-stress load in bolt maybe losing. Through studying and analyzing the field test data, the factors leading to pre-stress losing are both external and internal factors. The internal factors are cable steel wire loose and rock and soil mass creep deformation. In which the cable steel wire has been pre-tensioned, its affection for load losing is very little. While the rock and soil mass creep deformations have great affection to pre-stress loss. There, if the cable bolt is installed in hard rock, the rock creep deformation will be very little and the load losing in cable bolt will be very few. But if the cable bolt is installed in soft rock and soil mass, the creep deformation will be very much greater than in hard rock, and the pre-stress losing in cable bolt will be very great. The external factors are shocking load, such as blasting load, storm rainfall, temperature change and stress change of anchored rock mass. Through analyzing these affecting factors, some recommend the compensative measures which include choosing appropriate steel wire, pre-tensioning and over-tensioning cable bolt, controlling the blasting rigorous and monitoring the cable long time enough in work time.

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