bluuebunny/crossref_metadata_2025_split huggingface dataset:
Debris Flow Risk Assessment in Wudongde Reservoir Area Based on Analytic Hierarchy Process and Fuzzy Comprehensive Evaluation
Authors: Tan Chun , Ma Dong-He , Chen Jian-Ping , Zhang Wen , Xu Xin-Chuan 
Published: November 2020

Abstract
The outbreak of debris flow is a threat to human life and property, especially so in reservoir areas. Hence, it is critical to evaluate the risk of debris flow in the reservoir area. In this study, data were obtained through remote-sensing imagery interpretation and field survey. By using analytic hierarchy process, determined the weight of each evaluation factor was determined. Fuzzy comprehensive evaluation was applied for the debris flow risk assessment of Wudongde reservoir in China. The evaluation results show that the reservoir area has 20 mildly dangerous mudslides, 200 moderately dangerous mudslides, and 18 severely dangerous mudslides; only one debris flow ditch is extremely dangerous. Thus, the risk of debris flow in Wudongde reservoir area is relatively small and will not have a great impact on the construction and operation of hydropower stations here.
The hazard assessment of glacial lake debris flow: A case study on Dongcuoqu, Luolong County, Tibet
Authors: Ding Mingtao , Gao Zemin , Huang Tao , Hu Xiewen 
Published: November 2020

Abstract
The development and outbursts of glacial lake debris flow pose threats to downstream infrastructures. Thus, rational assessment of its potential hazards is necessary to mitigate geological hazards along the Sichuan–Tibet railway lines. In this paper, we used logistic regression models and Rapid Mass Movement Simulation methods to assess the multiyear dynamic evolutionary characteristics and outburst risks of the glacial lake and to conduct numerical simulation of the debris flow process. The adopted methodology used remote sensing images from the Landsat 1-Landsat 8 series for the period 1973–2018, combined with the pieces of information of the geological expedition in the glacial lake Dongcuoqu, Luolong County, Tibet, China. The results revealed that the probability of collapse risk of the Dongcuoqu glacial lake dam was 0.39, and its risk extent reached level I, which indicates medium hazardousness and severe loss. The debris flow process simulation comprises of four stages: initiation, acceleration, deceleration, and termination. The outburst floods flow through the proposed location of the Sichuan–Tibet railway. Specifically, the flow velocity in the vicinity of the Luolong station of nearly 5 m/s, which poses a significant threat to the safe construction of the railway. In the flood and non-flood periods, the change in the amount of snow and ice melt was distinctive, and the maximum storage capacities of the glacial lake during these periods were 82 × 106 m3 and 60.1 × 106 m3, respectively. These findings suggest that the assessment results can be used as an excellent reference for the reduction of the construction risk of the proposed Sichuan–Tibet railway under disaster stress in glacial lake outburst hazard areas.
Three-dimensional classification and zoning method of surrounding rock and its application based on big data geomechanical information
Authors: Yu S B , Yang X C , Wang H , Wang Z X 
Published: November 2020

Abstract
The study aims to address some prominent problems of the existing classification methods of roadway surrounding rock, such as poor adaptability and applicability. For this purpose, using geomechanical information coupling with the three-dimensional (3D) geological modeling technology, a 3D classification and zoning method of surrounding rock is proposed on the basis of the big data geomechanical information database. This method can realize advanced prediction and evaluation analysis of rock mass quality in unexposed areas. The method first establishes an acquisition workflow of the big data geomechanical information based on the rock mass rating (RMR) and then forms a statistics technology of the big data geomechanical information and database sample based on borehole core data. Finally, it realizes the assignment of RMR for the unexposed areas by combining the 3D evaluation technology of 3DMine software and the supplemented information obtained from onsite geological survey.
The 3D classification and zoning method is applied to the Jiama mine and compared with quality statistics obtained from an onsite survey. The results from the proposed model based on the borehole core database statistics are consistent with the onsite survey results. This indicates that the proposed method has excellent feasibility and applicability to solve some of the problems with the existing methods. In addition, the 3D classification and zoning method realizes extra mechanical application for borehole cores except for geological exploration and improves the application extent of borehole cores from multiple angles.
Surrounding rock control technology for the fault passing of mining face by removing gangue in advance from excavation roadways
Authors: Zhongcheng Qin , Bin Cao , Tan Li , Yongle Liu , Xin Guo 
Published: November 2020

Abstract
This study presents a new technology for passing through faults quickly by removing gangue in advance from driving roadways of working faces; this technology has the advantages of short moving time and good coal quality during fault passing. However, in practice, driving roadways are affected by mining pressure during the driving and mining period; thus, roadway support is difficult. This study aims to develop appropriate support for driving roadways, not only to ensure the stability of the roadway and satisfy the space requirements for the working face when it passes through the fault but also to reduce the strength of the rock pillars in the roadway. In this manner, the shearer can directly reduce the working strength during the period of fault passing. In this study, UDEC numerical simulation software is used to explore the size of rock pillars and the parameters of bolt support. In addition, the supporting effect of ordinary, high-strength prestressed, and high-strength prestressed yielding bolts is compared. On the basis of the simulation results, a reasonable control scheme of surrounding rock in advanced driving roadways is proposed. Moreover, the successful application of the technology in field practice shows the remarkable effect of this scheme on the surrounding rock control when passing faults. Thus, this study provides some references for surrounding rock control during the fault passing of the mining face.
Roof fracture and front abutment stress evolution of large mining height coal face with weak overburden under goaf
Authors: Liu X S , Li X B , Tan Y L , Ning J G , Fan D Y , Ma Q , Song S L 
Published: November 2020

Abstract
The mining pressure evolution of large mining height coal face with weak overburden under goaf is complicated, significantly influencing mining safety. This study uses the actual geological conditions of the II3 coal seam in Lingdong Coal Mine as research background. First, we combine the key layer theory and roof and floor lithology, the middle sandstone strata are determined as key strata. The fracture thin plate model for weak overburden with large mining height is established, considering elastic-plastic theory. We then obtain the calculation formula of key strata initial fracture span lo, periodic fracture span l0, and front abutment stress. Second, the roof fracture and front abutment stress evolution during lower coal mining are obtained using the FLAC3D numerical simulation method. As the coal face advances, the immediate roof continues to collapse, and periodic fracture subsidence occurs. The coal face periodically appears, causing the phenomenon of roof subsidence acceleration, serious coal wall spalling, increasing pillar stress, and roof-stepped subsidence. The numerical simulation results show that the initial fracture span is approximately 25 m, and the stress of the key strata is approximately 12.5 MPa. The roof weighting span of the first cycle is approximately 2.39 m, the front abutment stress peak is approximately 14.33 MPa, and the influence range of the front abutment stress is approximately 17.50 m. Finally, comparing the numerical simulation results with the theoretical results shows that the evolution is similar, verifying the correctness of the mechanical model. The research results can predict the periodic weighting of overburden and provide a reference for the design of roof mining pressure control for large mining height coal face with weak overburden of lower coal seam.
Dynamic Stability Evaluation of Underground Caverns in Jointed Rock Mass using Friction Energy Generated by Joint Sliding
Authors: Shuai Wang , Meiwan Yu , Shihu Xiong 
Published: November 2020

Abstract
General seismic damage surrounding underground excavations of jointed rock masses is closely associated with the presence and response of discrete fracture networks. As the failure of rock masses is mainly controlled by joints, energy dissipated through slippage along joints is proposed as an evaluation index for dynamic stability analysis of underground caverns. Energy dissipated in slippage is represented as a product of the shear stress and plastic shear displacement. The method was demonstrated through dynamic analysis of an underground cavern containing joints of varying dip friction angle and location. The results show that the proposed index can record the failure history and damage of rock structures surrounding an underground cavern subjected to dynamic loading. The effects of four types of joint sets on the dynamic stability of a cavern in the DaGangshan hydropower project were assessed using the friction energy of the joints. The combination of steep and non-steep joint sets was found to be much more unfavorable to large caverns than joints sets of only steep dip angle or non-steep dip angle.
On the genesis of karst in red beds and underground engineer risks analysis
Authors: Weibin Zhu , Siran Zhu , Hua Zhang , Huanghui and 
Published: November 2020

Abstract
Red beds are a series of red or dark-red clastic rocks that have been deposited in continental basins under dry climate conditions since the Mesozoic. Long-term investigation and research have found that karst caves in red beds mainly develop as formations composed of coarse-grained clastic rocks in the periphery of the basin. When combined with the overlying water-rich loose soil, these formations pose a significant risk to underground projects. The present study systematically analyzes several large-scale engineering implementations in the red bed layer, reveals the development characteristics of karst caves in red beds, and discusses the relevant causes (or mechanisms) of karst formation, which include the long-term effects of abundant soluble debris, tectonic fissures, and paleochannel systems. The characteristics of underground engineering methods, such as pile foundations, foundation pits, and underground tunnels, were evaluated to determine the main risks causing ground collapse and structural damage, such as water inrush, mud bursting, and slurry leakage. Risk models for different construction methods were finally established.
MCMC approach for shield tunnel grouting layer estimation using ground penetrating radar
Authors: Qin Hui , Tang Yu , Wang Zhengzheng , Xie Xiongyao , Zhang Donghao 
Published: November 2020

Abstract
Ground penetrating radar (GPR) has been suggested as an effective tool for evaluating the grouting layer behind shield tunnel linings, yet the estimation of the grouting layer thickness is usually difficult. In this paper, we propose a probabilistic inversion method to evaluate the grouting layer using GPR images. This method uses a sliding window along the GPR scan axis combined with a Markov chain Monte Carlo (MCMC) simulation with Bayesian inversion to infer the grouting layer thickness together with the relative permittivity and electric conductivity. We illustrate this approach using a synthetic GPR experiment that simulates grouting layer detection in a shield tunnel along the longitude direction. A sliding window with a width of 0.2 m is used to estimate the model parameters and is moved along the scan axis with a step size of 0.2 m after each inversion. The results demonstrate successful estimation of the grouting layer thickness and its relative permittivity and electric conductivity by the proposed method. Moreover, this method is capable of quantifying uncertainties in the inversion results.
Study on Thermo-Mechanical Coupling Characteristics of Surrounding Rock of HLW Disposal Repository in Clay Rock
Authors: Hai-an Liang , Long-peng Zhang , Jiong-feng Liang , Xin-jun Chai 
Published: November 2020

Abstract
With the long-term decay, releasing a large amount of heat is one of the main characteristics of high-level radioactive waste. Safe operation of high-level radioactive waste repository must consider the effect of thermo-mechanical coupling on repository stability. In this paper, core drilling samples and in-situ stress tests were performed systematically on clay rock in Tamusu area. Thermal conductivity and triaxial tests were operated on samples near the depth of target layer of repository, to obtain the thermal and mechanical characteristics parameters. According to these parameters, a repository model was established in FLAC 3D to simulate excavation of repository and thermo-mechanical coupling of surrounding rock within 100 years after it closed. Results reveal that thermo-mechanical coupling effect has a significant impact on stability of repository. Thermal field reaches a steady state when high-level radioactive waste releases for 20 years, and the temperature in surrounding rock decrease as negative exponential with the distance from the gallery increases of. Due the temperature of the surrounding rock increases, thermal stress is generated, and the stress level in the near field of repository is growing as a whole, thus, strain increases. After heating without support for 100 years, there is the possibility of shear failure at the top and bottom of the chamber. It is necessary to reinforce the chamber lining to ensure the safe and stable operation of the repository.
Study on influencing factors of cutting efficiency for TBM gage cutters by linear cutting test
Authors: Yin L J , Li M Z , Li X , Gong Q M , Wu F , Xu H Y 
Published: November 2020

Abstract
The gage cutter is the key component in a tunnel boring machine (TBM); this part affects the machine’s cutting efficiency and maintains the tunnel diameter. In this study, a series of rock cutting tests with different parameters (cutting spacing, penetration depth, and installation angle) is conducted using the mechanical rock fragmentation experimental platform of Beijing University of Technology to study the influences of these parameters on the rock-breaking performance of a TBM gage cutter. During the tests, the triaxial cutting forces and rock chips are collected and analyzed. The test results show that the average normal force of the cutter will decrease with the installation angle increasing at the same penetration depth and cutting spacing, but the average rolling force has the opposite change tendency. The side force is influenced by the installation angle significantly. The side force of the gage cutter plays a more important role in the rock fragmentation than does the side force of the normal cutter. Moreover, the cutting efficiency of the normal cutter is higher than that of the gage cutter. An inclined disc cutter is more conducive to producing rock chips under a large cutting spacing than is a vertical disc cutter, and the optimal cutting spacing under different installation angles is different. This study can provide a reference for TBM gage cutter design and TBM operation parameter optimization.
Dynamic Response and Perturbation Design of Surrounding Rock in Blasting Construction of Small Radius Spiral Tunnel
Authors: Fang Z B , Yan Q , Sun X D , Fu D , Zhang X X , Liu X , Qi N 
Published: November 2020

Abstract
To achieve a better blasting effect of ultra-long and deep buried spiral tunnel with a small radius, it is necessary to study the dynamic response and disturbance of blasting construction. As the engineering background with a poor engineering geological condition, this paper uses the Midi spiral-tunnel in Yunnan province that has a small radius of curvature, a large burial depth, and a large excavation distance. The blasting load is determined first by calculation. Under different blasting construction parameters, the deformation and dynamic vibration responses of the surrounding rocks are studied using the finite element numerical method. The damage mechanism of rock under the blasting load is analyzed. The tunnel engineering blasting is designed and calculated, and the small distance disturbance design of spiral tunnel blasting construction with a small radius is performed from the excavation method and blasting parameters. The results serve as a reference to reveal the surrounding rock dynamics in blasting construction of the spiral tunnel with a small radius.
Optimization Analysis of Suki Kinari Underground Powerhouse Caverns Based on an Efficient CATIA-Abaqus Model
Authors: Li Hui , Chen Wei-zhong , Chen En-yu , Tan Xian-jun , Wang Xiao-gang , Hu Yuan-jun , Wang Yu-xuan 
Published: November 2020

Abstract
Underground powerhouse caverns, which are large-scale, complex-type, and intersecting circuits, are considered as a complicated, constrained, and irreversible nonlinear system. They are divided into several layers for excavation. Various stress states occur whenever they are subjected to excavation; therefore, deformation and failure arise because of stress redistribution and concentration. Based on the determinate excavation scheme, the sectional shape of underground powerhouse caverns, especially the aspect ratio of the main powerhouse, is the key factor that affects the stability of the surrounding rock masses. Furthermore, during the excavation process, the integrity and stability of rock pillar, whose thickness is determined by the interval of caverns, are considered as crucial issues, because damage occurs in the thinner rock pillar. Consequently, the interval of caverns is the important parameter that needs to be investigated. In this study, we combine building information modeling with numerical analysis to investigate the effect of the aspect ratio of the main powerhouse and the interval between the main powerhouse and the main transform chamber. For the Suki Kinari (SK) underground powerhouse caverns, the 3D terrain and geological model was created in accordance with the detailed geological information. The parameterized underground powerhouse model and the supporting system were designed by CATIA, and the numerical model that involves the excavation scheme was generated by ABAQUS. The results show the following: (1) As the aspect ratio increases, the deformation of the main powerhouse exhibits various features, indicating that the arch crown settlement reduces while the deformation of the sidewalls increases. (2) As the aspect ratio increases, the overall deformation of the particular parts exhibits the characteristic of rapidly decreasing and then gradually forming a convergent trend. (3) Intense disturbance occurs on the rock pillar because of bidirectional unloading during the excavation process, and the rock pillar weakens rapidly and then gradually stabilizes as the thickness increases, suggesting the property of exponential function of the total deformation. Finally, the conclusions are applied on the SK underground powerhouse caverns to reveal the optimal aspect ratio and interval.
Composite collapse mechanism of an anti-dip rock slope
Authors: Sun Chaoyi , Chen Congxin , Zheng Yun 
Published: November 2020

Abstract
Collapse is a common instability mode of anti-dip rock slopes. This type of failure involves a complex geo-mechanical process. This work investigated the collapse mechanism of an anti-dip rock slope in a granite mine in Shanxi Province, China. A detailed field survey was carried out to analyze the inducing factors and failure process of collapse. Then, discrete element numerical simulations were conducted by the Universal Distinct Element Code (UDEC) to determine the microscopic damage and macroscopic failure of collapse. Through these works, the composite collapse failure mechanism of the anti-dip rock slope was investigated comprehensively. Results show that the structural planes perpendicular to the slope surface and the steep anti-dip structural planes are the prerequisites of collapse. Strength softening of the structural planes caused by rainfall is the triggering factor of collapse. The collapse of such a rock slope can be considered as a composite failure composed of shear sliding, block toppling, and flexural toppling. In addition, the numerical results indicate that the composite failure of shear sliding and block toppling occurs at the toe of and the middle of the slope, followed by flexural toppling failure at the rear edge of the slope. Therefore, the monitoring and treatment of such type of collapses should be concentrated on the composite failure zone where shear sliding and block toppling occur. The high consistency between the numerical results and field observations shows the feasibility and rationality of using UDEC to study such collapse from the microscopic damage to macroscopic failure. The results enrich the type of collapse of anti-dip rock slopes and provide a scientific reference to the design treatment for such slopes.
Analysis of the Finite Element Strength Reduction Method to Slope Stability with a thin weak layer
Authors: Luo Hongming , Zeng Chao , He Xianzhi , Li Weipeng , Li Qun 
Published: November 2020

Abstract
The strength of the weak layer not only controls the instability mechanism of the slope, but also the factor of safety to the slope. Studying the stability of the weak layer slope has important theoretical significance and practical engineering value. The instability mechanism and the factor of safety to slope stability with a thin weak layer were studied by finite element strength reduction method and limit equilibrium method. The results show that factor of safety to slope stability decreases with the strength of the weak layer decreases. When the strength of the weak layer is less than 0.6 times the strength of the soil, the instability mechanism of the slope changes from circular arc sliding to polygonal sliding, and its stability is controlled by the strength of the weak layer. The slope stability analysis by limit equilibrium method must be based on the analysis of the instability mechanism to accurately evaluate the slope stability. However, the finite element strength reduction method can be applied to calculate the factor of safety to slope stability and analyze the instability mechanism, and to previous limit equilibrium method.