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ABSTRACT: Ma'anziliang long highway tunnel is typical separated tunnel of Shiyan-tianshui expressway which is located in complicated geological conditions in Qinba mountain area. Reliability of initial support of grade V surrounding rock section was analyzed by using finite element method. The supporting structure of the highway tunnel is important to traffic safety. Ma'anziliang highway tunnel is a typical long tunnel under complicated geological conditions. According to lithology of grade V surrounding rock and primary support parameters, the structure factor of safety was calculated about bolt resistant tension, bolt length and shotcrete force through finite element method. As a result the reliability is evaluated and the coefficient is 0.588, but integral structure will be steady if taking secondary lining into account. During the process of tunnel construction and using, the safety of primary support need to be analyzed and evaluated. At present, the analysis methods of primary support reliability in highway tunnel were probabilistic methods and finite element method. For example, the finite element simulation method was usually used in calculation of slope safety factor, which could analyze the stability of slope (Chen & Liu 2010, Liu et al. 2009, Zheng et al. 2005). In recent years, the evaluating method using safety factor of surrounding rock stability and support structure was used in underground works (Han & Su 2011, 2012, Han 2012). Depended on Ma'anzi Liang tunnel in QinBa mountain, this paper mainly was acquired the safety factor of primary ·support in surrounding rock V. At the same time, the reliability of support structure was evaluated. PROJECT OVERVIEW OF MA'ANZI LIANG TUNNEL 1.1 Tunnel introduction Ma'anzi Liang tunnel is a typical separate type and longer tunnel in ShiTian xian highway. Right line start at YK34+614~YK39+539 and the total length is 4925 m. The pile number of V-class surrounding rock were (YK34+625~YK34+728 (103 m), YK38+467~YK38+693 (226m) and YK39+372~YK39+533) (161 m). The New Austrian Method was used in this tunnel, and bench method was used in excavating in the area of V-class surrounding rock. Among them, reserved core soil was taken annulary in excavating in upper bench and lower bench partially staggered around the excavation.
ABSTRACT: This article aims at more accurately studying an equivalent applying way of blasting load by numerical simulation method. Based on the theory of strength reduction, slope stability is analyzed. It can produce special blasting load when open-pit is mining, and made more able to simulate the actual blast load equivalent loading. The equivalent applying way of blasting load first analyze the characteristics of open-pit blasting load, it rings to pass from the explosion source to the surrounding, If the blasting load can equivalently load into the crushing outside the district boundary, so that it is more consistent with the actual hole blasting; The way uses FLAC3D to establish the open pit slope numerical model, and then analyzed using finite difference method under blasting dynamic loading the dynamic response characteristics of slope, then calculated using strength reduction pit slope seismic safety factor. And finally with the past will be the equivalent of blasting vibration is applied to the model boundary manner comparative, verification by the equivalent method is applied to blasting in the slope stability analysis under dynamic loading, the feasibility and rationality. 1 INTRODUCTION Since the 20th century, the ore proportion of both domestic and overseas open-pit mining is considerable in ore yield. For our country (Liu 1995), metal mine open-pit mining of iron ore accounts for about 80%-90%, non-ferrous metals accounts for about 40%-50%, and chemical materials accounts for 70%, building materials accounts for 100%, proportion of open-pit coal mining has been about 5%. In recent years, some large open-pit mine areas have set up, which suggests that the development potential of coal mining in future is very huge. Since the 1990s to the beginning of this century, with the development and utilization of resources, deep sunken open pit mine has become the trend of the open-pit mine in the world, and the resulting high steep open pit slope stability problem has been closely watched. With the rapid development of science, technology, economy, the excavation blasting technology is widely applied in open pit mining. But because of its complexity and moments in blasting, it is difficult to study its mechanism and function feature. At present, the problem of slope stability under blasting load research has aroused many scholars attention.
- Materials > Metals & Mining (1.00)
- Energy > Oil & Gas > Upstream (0.95)
Numerical Tests on Failure Process of Rock Slopes With a Weak Stratum
Tang, L. X. (University of Science and Technology Liaoning) | Yang, Y. J. (University of Science and Technology Liaoning) | Wen, Y. L. (University of Science and Technology Liaoning) | Chang, S. (University of Science and Technology Liaoning)
ABSTRACT: Rock structure is very important for the stability of rock slopes. RFPA is a professional finite element software for failure process analysis of material. RFPA-Centrifuge is used to simulate the failure process of rock slopes with a weak stratum which is in different height, the characteristics of the failure processes of the three dimensional-models and the factors of safety are gotten. The results showed that with the same mechanical parameters, the shorter distance between the weak stratum and the crest of slope is, the bigger the factor of the safety is and the smaller of the instability area is. Therefore, using software to simulate the failure process of slopes before the engineering excavation, different measures will be provided reference for supporting on rock slopes with weak strata. 1 INTRODUCTION Mostly rock mass at surface layer of earth had formed many structure planes with regular distribution in lengthy geological history. For rock slopes, stability analysis is difficult because there are so many discontinuity structure planes in rock mass, which has different construction and characteristic. Such as layer plane, joints, fracture, weak interlayer, vein, etc. Engineering rock mass has complex geological occurrence environment, the force conditions and border conditions are kaleidoscope, it's very difficult to express stress state and stability with classic mathematics mechanical method, this is restricted with the development of joint rock mass mechanics in a long time. The rapid development of computer technology changed this status, numerical calculation methods gradually became tools for rock mechanical research and engineering calculation. Weak strata are the weakness places in rock mass under dynamic loading conditions because of the lower modulus and strength, which is usually impact on the engineering projects. In recent years, the dynamical problem of rock slope with weak strata has caused widespread attention in the geotechnical engineering field (Huang 2007). Du Xiao-li (Duet al. 2010) discussed the relationship between the inclination of structures and slope stability by finite element method. Chai Hong-bao (Chai et al. 2011) studied the amplification rule of slope under the action of vertical upward shear wave. Huang run-qiu (Huang & Yu 2003) simulated the impact of magnified effect of earthquake wave with elastic-plastic parameters involving weak interlayer, and obtained the results that magnified effect is mainly related to velocity, not density.
ABSTRACT: The tertiary soft rock (or tertiary hard soil) is half-diagenetic rock (soil) and its properties are different from hard rock and soil. A lot of engineering practices show that the stability of thick tertiary soft rock slopes is affected seriously by underground water and rainfall. A high open-pit slope which is made up of super-thick tertiary soft rock is taken as a case, firstly the variation laws of the physical and mechanical parameters of the tertiary soft rock in this slope with different water content had been analyzed through drill hole sampling and laboratory testing. Then a fluid-solid coupling model had been established based on the limit equilibrium theory, finite element method and saturated-unsaturated seepage theory, to study the effect of seepage field caused by underground water and rainfall on the stability of the slope. The experimental and numerical results show that the cohesion of the tertiary soft rock is rather sensitive to water content but the internal friction angle is insensitive; the slope will be unstable in the present level of underground water, and only the depth of waterline is dropped for 100m can the slope be safe; both transient saturated zone and pore water pressure increase with longer duration of rainfall, but the heaviest rainfall can only lead to the shallow slope sliding within the thickness of 20 m and local rainfall has less impact on the whole slope stability. 1 INTRODUCTION The stability of slopes greatly affects the economic benefits and production safety of open-pit mines in the process of strip mining, so studies on open-pit slopes have always been the hot subjects. There have many research achievements on the issues of hard rock slopes, soft rock slopes and soil slopes in the field of open-pit mines, hydroelectric dams, highway and railway slopes etc (Naghadehi et al. 2013, Dine et al. 2011, Huang 2007). However, the tertiary soft rock (or called the tertiary hard soil) is a kind of half-diagenetic soft rock (soil) which is in the status from soil to rock, and at present there aren't targeted rules and enough research results for determining the bearing capacity of this kind of rock by existing different standards (Zhang & Qu 2000a). A lot of engineering practices show that the tertiary soft rock (soil) is a kind of regional special soil which is highly vulnerable to environmental changes (including the natural environment and engineering environment) and has significant drying shrinkage and water absorption expansion characteristics (Zhang & Qu 2000b, Feda et al. 1995).
- Materials > Metals & Mining (1.00)
- Energy > Oil & Gas > Upstream (1.00)
A Probability Method of Slope Unit Stability Analysis Based on Reliability Index
Dong, B. (State Nuclear Electric Power Planning, Design and Research Institute, Beijing) | Wang, X. B. (State Nuclear Electric Power Planning, Design and Research Institute, Beijing) | Liu, X. Y. (State Nuclear Electric Power Planning, Design and Research Institute, Beijing)
ABSTRACT: The slope unit method provides an effective tool for the analysis of landslide stability in the mountain region. The combination of the classical mechanics theory and probability statistics offers the popularity of the qualitative and quantitative evaluation of slope stability. In this paper, by dividing the slope unit on the target region, the three-dimensional safety factor by limit equilibrium model was obtained by using the non deterministic probability density function of reliability evaluation. According to this method we can determine the risk grading of the slope unit instability probability. 1 INTRODUCTION Landslide disasters usually cause serious casualties and property losses, and they are also social problems received wide concerning. The correct analysis methods of the failure probability of landslide disaster area are significant for the landslide dis· aster prevention. So far the recognition methods for a wide area of geological disasters are divided into two categories: Deterministic and non deterministic evaluation method. The deterministic evaluation methods are based on the landslide area terrain, geology, rock and soil mechanics properties etc. Also, the mechanical evaluation model can be used to analyze the slope stability, especially the limit equilibrium method, numerical simulation and the block theory etc. The non deterministic evaluation methods are the use of mathematical statistical methods (failure probability method, reliability analysis method) and the coupling mechanics models. They are based on the study of mathematical statistical method. Using GIS and the remote sensing, the regional geologies, the tilt angle, the valley density, fault, vegetation, terrain classification and dimensions are collected to generate spatial distribution map. The weight of each factor is given to produce the superposition factor and make the comprehensive evaluation index distribution map, the formation of unstable landslide region as well.
ABSTRACT: By means of introducing strength reduction method and gravity increase method to particle flow code, the stability of the jointed rock slope is analyzed. In the analysis, rock is described by the particles and their contacts, and joints by the smooth joint model. Meanwhile, there is no longer need predefined constitutive relation or presupposing sliding surface. After strength reducing or increasing gravity, the fractures generate, propagate, and coalesce along the contacts with minimum tensile or minimum shear strength, forming the final sliding surface. Comparing with traditional limit equilibrium method, the result of particle flow code is more reliable in obtaining the safety factor and has more advantages in determining the sliding surface. It will provide a new approach for the stability analysis of jointed rock slope. 1 INTRODUCTION After repeated geological action, rock mass in slope primarily composes of rock and structural surface. The structural surface can divide into bedding plane, joint, crack and fault fracture zone, due to its structure, occurrence, and characteristics (Chen 2005). The rock mass is cut into structures with different sizes, shapes for the presence of structural surfaces, as a result, it exhibits discontinuity. What's more, the rock strength is always determined by the structural surfaces because of their extremely low strength properties. Specially, joint is one of the important structural surfaces. The main methods analyzing slope stability are traditional Limit Equilibrium Method (LEM), Finite Element Method (FEM), Discrete Element Method (DEM), etc. LEM is mainly applied to homogeneous slopes (Bishop 1955). This method requires pre-defined sliding surface shape and location with artificially, and it does not consider the relationship of sticks' stress and strain. FEM has considered the stress and strain relationship, and can qualitative evaluate the slope stability according to nodes' displacement and plastic strain zone. In recent years, Zheng & Zhao (2004) incorporated strength reduction method and gravity increase method into FEM, which not only calculated the safety factor, but also showed the sliding surface corresponding to the minimum safety factor.
Evaluation Model for Predicting Affected Area of Debris Flow Induced by Rock Landslide
Liu, X. Y. (State Nuclear Electric Power Planning, Design and Research Institute, Beijing) | Cai, W. (State Nuclear Electric Power Planning, Design and Research Institute, Beijing) | Wang, Y. (Jiangsu Nuclear Power Co. Ltd.)
ABSTRACT: Debris flow caused by the landside is one of complicated geologic hazards in mountain area, which is closely associated with geology, lithology, the mechanical characteristics of the rock and soil, rainfall, groundwater and land usage condition etc. The analysis of immanent relationships between landslide and Debris flow can not only provide some important information about landslide failure mechanism, but also be used as the basis of evaluation of Debris flow triggered by landslides. In this paper, the depth integral was applied in two-dimensional mathematical model of Debris flow which is based on the principle of conservation of mass and viscous Newtonian fluid Navier-Stovkes equation. Then, this equation was numerically computed by using the finite difference method. The relational expression between streams tilt angle and the width of affected range of Debris flow, which is obtained from statistics, was applied to analyse the possibility of Debris flow induced by landslides which once failed under the similar geological conditions. Combining with GIS, the model can also be used to predict impacted range of Debris flow by using risk map to show the zones that may be affected by the Debris flow. 1 INTRODUCTION Majority Debris flows usually happen after the occurrence along stem from the landside by the rainfall. They are results of the area of the landslides advanced to valley. The debris flows have the characteristics of sudden eruption, intermittent and enormous energy. Because of the destructive power, the debris flow may cause heavy casualties and serious economic losses. Therefore, the prediction of disaster area and motion trajectory has already become one of the most important the risk assessment. Geographic information system and digital model has become a practical and effective means in analyzing geologic hazard. These two techniques have strong treatment ability of spatial data and the attribute data, and can also be efficiently solved in data collecting, data processing, and data analysis about landslide and debris flow. By the method of the interaction between sensitivity factor of spatial distribution and digital model to assess to the hazard of the debris flow gully become hot spot.
- Geology > Geological Subdiscipline (0.68)
- Geology > Rock Type (0.67)
- Data Science & Engineering Analytics > Information Management and Systems (1.00)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid selection and formulation (chemistry, properties) (0.49)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (0.34)
ABSTRACT: Based on the theory of the limit equilibrium method of slope stability analysis, this article studied the infinite slicing calculate theory under the circumstance that the loess slope sliding-plane does not cross the slope foot. Through the formula derivation, the analytic formula of the sliding torque Mr, and resisting moment Mf were calculated, and then it was concluded that the safety factor K is function of the smooth arc radius R, the sliding body string angle a and angle of slope plane distance Δl. We simplified the process of searching the most dangerous sliding surface on genetic evolution method reasonably and effectively. On the basis of concept of replication, hybridization, variation, competition and selection in biological genetic evolution steps, in the process of the most dangerous sliding surface search, change the two-way variation for one-way and increase mutant genes of the slope angle of plane distance. While other factors remain unchanged and only one of the factors changes, the minimum safety factor was computed under the restrictive condition and its applicability was determined. After changing another factor and repeating the searching process, the minimum safety factor and the corresponding value of various factors were figured out finally. Realizing search on the most dangerous sliding-plane does not cross slope foot. Also, we used FORTRAN software program to complete the compilation of the search procedures. The engineering examples have confirmed that this method is feasible and safe. This paper has important value of reference to improve the loess slope stability analysis theory. 1 INTRODUCTION At present, the theory of the limit equilibrium method is the main approach to analyse slope stability. However, it simplifies the boundary conditions of the landslide. Different assumptions lead to various theory of limit equilibrium method of slope stability analysis. The common theories are Bishop, Janbu, Spencer, Morgenstern-Prince and so on. For various limit equilibrium methods stand for different hypothesis, they make remarkable effect on results and precision. At the same time, these methods have complete and meticulous theoretical derivation. Because the methods themselves make some simplifying assumptions. Thus some unavoidable limitations and the final results are often different from the engineering practice, which may leads to low precision of results because we can only rely on the experience of slopes. In view of that, particularly on loess areas, it's eager to make an intensive study of each past theory to draw more precise limit equilibrium methods of slope stability analysis to guide the project. Moreover, it could reduce disasters of engineering to secure the safety of people's life and wealth.
ABSTRACT: There is a large burning area in Xinjiang Laojunmiao open pit coal mine. To ensure the slope safety, characteristics of surrounding rock after baked and burnt were understood through the geological investigations and the rock mechanics tests. The typical profiles of burning area were selected according to the engineering geological characteristics. The safety factors of the profiles in the different final slope angles and the different states were computed through the limit equilibrium method, then the stabilities were analyzed to determine the reasonable final slope angle. The results show that strengths of burnt rock decrease compared with original rock. When the final slope angle of Laojunmiao mine is 36°, the slope safety can be ensured. 1 INTRODUCTION Due to the dry climate and shallow coal seam in Xinjiang, coal-field fire are very serious. According to statistics (Cai & Wei 2008), there are currently 50 coal-field fire areas in Xinjiang, and the total area is about 570m, which lead to the loss of more than 15 million t coal. A large burning area is formed after the coal spontaneous combustion, causing a serious impact on safety production of mine. Many scholars have studied the coal spontaneous combustion, burning area and burnt rock and achieved certain results. Ide et al. (2011) delineated the range of coal fires in underground area by magnetic method, and the geomagnetic characteristics were studied and reported. Heffern & Coates (2004) made a detailed study on distribution and cause of the geologic history coal fires in the Powder River Basin of the United States and used a variety of dating methods to date burnt rocks. Hoffman et al. (2004) used differential interferometric synthetic aperture radar to detect the coal fires in northern China. Christian et al. (2009) detected the range of coalfield fires using thermal infrared remote sensing technique. Voigt et al. (2004) conducted a survey to detected and analyzed coal seam fires in north China using integrating satellite remote sensing techniques.
- Asia > China (1.00)
- North America > Canada > Alberta (0.45)
- Geophysics > Magnetic Surveying (0.68)
- Geophysics > Electromagnetic Surveying (0.44)
- North America > United States > Wyoming > Powder River Basin (0.99)
- North America > United States > Montana > Powder River Basin (0.99)
- Asia > China > Xinjiang Uyghur Autonomous Region > Junggar Basin (0.99)
- Europe > United Kingdom > England > London Basin (0.91)
- Well Drilling (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Coal seam gas (0.55)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (0.48)
- Reservoir Description and Dynamics > Reservoir Characterization > Reservoir geomechanics (0.35)
ABSTRACT: The study concentrates on the safety factors involved in rock slope stability of an open-pit porphyry copper mine. The analysis of the safety factors are based on the comparison of different optimized slope angles and the slope stability in different geological zones is also included in the research. By applying the methods of Flac3d and the limit equilibrium analysis, it can determine the possible failure zone and reasonable slope angle for open-pit mining. The conclusion is a great contribution to the following mining design and further production practice for open pit mining. 1 SURVEY OF MINING AREA The mining area is located in the oblique east wing of the back of Xibeikulasi, and is relatively flat, which belongs to the low mountain hilly terrain. The altitude is 770 meters, the relative elevation is generally of 5 to 15 meters, and the scope of mineralization is an oval area with the length and width of about 1.0 km. The exposed stratum is Xibeikulasi Shangya Formation (C1X2) and Baogutu Xiaya Formation (C1B1) of Lower Carboniferous Series. The stratum is in nearly north-south direction, with tendency to the east and the dip angle of 60° to 70°. 2 SLOPE ROCK MASS QUALITY CHARACTERISTICS The partition of the geology of the copper mine project is taken according to the surrounding topography and lithology around the area, combined with field geological survey and additional exploration results. During the partition, the hydrogeological conditions, fault joints and the engineering factors and geological factors of the crushed zone have been overall considered. The strip mine is divided into six.
- Geology > Mineral > Native Element Mineral > Copper (0.82)
- Geology > Rock Type (0.80)
- Geology > Geological Subdiscipline (0.69)
- Geology > Structural Geology > Tectonics > Plate Tectonics > Earthquake (0.30)