bluuebunny/crossref_metadata_2025_split huggingface dataset:
Applied research on slope reinforcement with cement mixing pile in deep soft soil foundation pit
Authors: Zhong yi WEN , Zi cong FAN , Li juan ZHANG , Zhao bin WANG 
Published: November 2020

Abstract
Deep Quaternary soft soil layer with poor mechanical properties are widely distributed in the Pearl River Delta. In this paper, based on engineering examples, a numerical simulation method was used to study the action mechanism of new reinforcing techniques of grading slope combined with cement mixing piles. The effect of construction conditions, the thickness of the cement mixing piles, and reinforcement of the passive zone on the deformation and overall stability of a foundation pit were analyzed. Finally, the simulation results and the actual monitoring data were compared and analyzed to further verify the rationality of the model. The research reveals that the step-slope combined with cement mixing pile reinforcement has significant effects on limiting the deformation of deep foundation pit and ensuring the stability of the pit. The findings of this study can serve as a reference for similar researches[1].
Mechanical properties of organic-rich shales based on nanoindentation: A case study of deep shale gas reservoirs in Zigong area, Sichuan Basin
Authors: Jia Lichun , Deng Hu , Liu Dianchen 
Published: November 2020

Abstract
The deep shale gas in the Zigong area of the Sichuan Basin has a wide distribution and has good prospects for exploration, which has become an important replacement area for shale gas exploration and development. In this area, the burial depth of Longmaxi Formation Shale is generally >3500 m. One of the most challenging tasks in the development of this type of reservoir is the accurate prediction of the mechanical properties of organic-rich shale. The application of the mechanical properties of shale is important to the success in multiple aspects of drilling, hydraulic fracturing, and production. Methods such as unconfined/triaxial compression tests with the use of core plugs and logging data interpretation are commonly used to obtain mechanical properties. However, these methods have their own limitations. Thus, to address the difficulty in the measurement of the mechanical properties of shale, the advanced nanoindentation test is introduced and used. Nanoindentation is a technique based on a hard tip, which is pressed into the surface of a sample. The advantage of this test is the use of a sample with a small volume, such as drill cuttings or fragments, which are easily obtained during drilling. The mechanical properties at the nanoscale level, including the hardness, Young’s modulus, and fracture toughness, are measured in the nanoindentation. Moreover, this technique can be used to evaluate the creep behavior of shale. In this study, grid nanoindentation is used to investigate the mechanical properties of drill cutting samples from the Longmaxi Formation Shale in Zigong area, Sichuan Basin. Subsequently, these mechanical parameters are used to evaluate the heterogeneous properties of shale at the nanoscale level. The results can help in analyzing the correlation between rock mechanical properties and shale constituents. This suggests that the nanoindentation test is a useful approach of estimating the elastic and mechanical properties of shale in situations where conventional rock mechanics test data cannot be measured.
Study on Rock Burst Behavior and Tendency Identification of Surrounding Rocks in Hard and Brittle Formations of Deep and Ultra-deep Wells
Authors: Zeng Yijin , Chen Junhai , Li Dandan , Li Xin 
Published: November 2020

Abstract
The phenomenon of the continuous collapse or the instantaneous block-falling incidents during the drilling of deep wells cannot be sufficiently explained by traditional wellbore instability theory. This phenomenon is similar to rock bursts that often occur during tunnel excavations and other engineering projects. This paper focuses on hard/brittle formations such as limestone, dolomite, and shale, which represent the most frequently collapsed formations while drilling a borehole. Based on rock burst theory and the results of the rock mechanics experiments, combined with rock failure model and other intuitive conditions, rock bursts are divided into three categories: weak, medium, and strong bursts. We establish the calculation models of strength brittleness index R and elastic energy index W based on rock uniaxial compressive strength and determine the interval values of these indexes for rock burst identification. We also propose a set of comprehensive identification methods for rock burst tendency and the classification of surrounding rocks in hard and brittle formations during the drilling of deep wells. The findings of this work provide a solid foundation for the research of wellbore instability prevention and control based on the classification of hard/brittle formations.
Experimental investigation of rock cuttability based on rock indentation tests by a conical pick
Authors: Wang Shaofeng , Tang Yu , Li Xibing , Wang Shanyong 
Published: November 2020

Abstract
Stress conditions and rock properties significantly influence rock breakage. The rock indentation tests by a conical pick were conducted to investigate the rock cuttability corelated to confining stress conditions and rock strengths. Based on the test results, the regression analyses were used to find the relationship among rock cuttability, uniaxial confining stress applied to rock, uniaxial compressive strength (UCS) and tensile strength of rock material. It was found that the regression models can accurately reflect the variation law of rock cuttability, which presents decreases followed by increases with increases in uniaxial confining stress and the negative correlation to UCS and tensile strength of rock material. The established models are suitable for guiding the rock cutting by conical pick and will provide useful information for mechanized mining in deep hard rock.
Evaluation and optimization of existing force prediction models for TBM disc cutters based on full-scale rotary cutting tests
Authors: Tang Miaoyuan , Huang Xin , Zhuang Qianwei , Zhang Chi , Wang Shuaifeng 
Published: November 2020

Abstract
A variety of theoretical or semi-empirical models have been proposed to predict the forces acting on the disc cutter and the wearing degree during TBM tunnelling. These models were developed based on different cutting scenarios with specified assumptions, which unavoidably have limitations. A series of full-scale rotary cutting tests on a circular specimen with an outer diameter of 3.3 m assembled from granite blocks collected from site were conducted in a multi-functional disc cutting platform. Different cutting parameters were considered, including different penetrations, rotatory speeds, and cutting radiuses. Variation of three orthogonal axial forces acting on the disc cutter during the experiments was obtained. The topology of cutting grooves was measured using the laser vision sensors, from which the information of specific energy was derived. The effectiveness of different theoretical models in predicting disc cutting behaviour was assessed by comparing the predicted force values with experimental data.
Construction and application of a PCC energy pile model test system
Authors: Gao Lei , Gong Yunhao , Zhou Hui , Li Ping 
Published: November 2020

Abstract
PCC energy piles represent a new type of energy pile technology. At present, research on the bearing characteristics of PCC energy piles is relatively limited. This study designs and builds a PCC energy pile model test system, including a model pile, optical fiber sensors, and heat transfer, loading, and data acquisition devises. The system is used to study the bearing characteristics of PCC energy piles under different temperatures. Results show that the temperature of the pile is transferred to the soil along the radial direction under the action of a circulating temperature and the moisture in the soil around the pile migrates along the direction of heat transfer. The migration speed increases when the temperature gradient is large. At the end of circulation, the displacement of the pile top increases by 0.6% D, the resistance at the pile end increases by 1.28 times, and the maximum strain point of the pile body is 70%L from the pile top. The PCC energy pile test system proposed in this work is feasible and applicable.
Offshore Cone Penetration Test and Its Application in Full Water-Depth Geological Surveys
Authors: Lu Y , Duan Z , Zheng J , Zhang H , Liu X , Luo S 
Published: November 2020

Abstract
Characterizing seabed sediments is one of the most important processes in marine engineering surveys. Marine sediments, which are characterized by low strength, typically consist of soft fine-grained sediments (either clay, or in some regions, carbonate muds and silts) that have been deposited relatively slowly. Sampling these soft sediments is extremely difficult, and in situ testing is preferable. Cone penetration test (CPT) is widely used due to its prominent advantages in accurately determining the physical-mechanical properties and types of seabed sediments. Due to the world’s escalating demand for energy, combined with the continued depletion of oil and gas reserves in shallow waters, offshore engineering has moved beyond the immediate continental shelf into deeper waters and untested environments, thus posing a challenge to the operating water depth of CPT. The paper presents an overview of recent developments and applications in CPT technology associated with different water depths, including the cone penetration equipment suitable for the beach/shallow sea, the areas with normal water depth, and the extremely deep sea. Furthermore, the nature of CPT design has changed radically partly due to the types of engineering and partly because of the specific nature of the seabed sediments. Thus, the CPTs with multiple functions are also reviewed.
Anelastic strain recovery in situ stress measurement method and its application prospect in underground mines
Authors: Sun Dongsheng , Chen Qunce , Li A-wei , Yang Yuehui 
Published: November 2020

Abstract
Current stress state data are important in underground mine construction, analysis the of tunnel stability, the forecasting of coal and gas rock bursts in underground mines. At present, the hollow inclusion gauge is primarily used for in situ stress measurement in underground mines. However, the sensors of these gauges often fail to fully adhere to the borehole wall, which can reduce the reliability of the measurement results. In this study, the anelastic strain recovery (ASR) in situ stress measurement method based on oriented cores is introduced. The effectiveness of this technique is analyzed by comparing the test results with those obtained by the hydraulic fracturing method. In addition, the reliability of the ASR method is evaluated by repeatability testing. The ASR results indicate a horizontal minimum principal stress error of less than 10% compared with those obtained by the hydraulic fracturing method. The repeatability test results show good consistency in the in situ stress measurement results of two back-to-back test samples. The ASR method is a safe and highly efficient technique that is not limited by the depth and measurement environment. Therefore, it is expected to have broad application for underground mine in situ stress measurement.
Experimental Study on Dynamic Evolution Mechanism during Coal and Gas Outburst
Authors: Geng Jiabo , Nie Wen , Yang Shun , Li Qihang , Xu Jiang 
Published: November 2020

Abstract
Coal and gas outburst is one of the most serious disasters in coal mining. To research the outburst evolution mechanism, we used the multi-field coupled coal mine dynamic disaster large-scale test system for simulating coal and gas outburst. In the present study, the evolution characteristics of gas pressure, temperature, and coal body stress during the outburst process were explored. Experiment results show that (1) the coal seam gas pressure decreased faster where the position is closer to the outburst, and the spherical shell-shaped outburst wave front formed in the coal seam propagated rapidly from the outburst outlet to the inside; (2) during the process of coal and gas outburst, the elastic energy of coal body released instantly, which slightly increased the temperature and then the gas desorption absorbed the heat, thereby slowly dropping the temperature; (3) after the outburst, coal and gas released the pressure, and the stress inside of the coal body decreased. The reduction of stress around the outburst hole was the most obvious.
Characteristic analysis of the Nayong rock avalanche based on the seismic signal
Authors: Luo Hao , Yin Yueping , Xing Aiguo , Jin Kaiping , Xu Shimin , Zhuang Yu 
Published: November 2020

Abstract
A rock avalanche that destroyed 23 houses and killed 35 people occurred on August 28, 2017 in Nayong, southwest China. A discrete element model, MatDEM, was combined with the dynamic parameters of seismic signal inversion to determine the kinematic behavior of rock avalanches. The best fitting parameters were identified by comparing the velocity evolution process of numerical simulation with that of seismic signal inversion. The dynamic process obtained by modeling was compared with the frequency distribution spectrum of the nearest seismometer, with results revealing that the dynamic process agrees with the parameters inverted from the seismic signals. The simulation results further indicate that the movement process lasted for nearly 40 s, with a maximum speed of 40 m/s. The selected models and parameters can help provide a more accurate explanation of the dynamic processes of similar rock avalanches and are significant to hazard prediction in karst areas.
Study on the integrated planning of deep mining considering rock burst prediction
Authors: Chen L , Wu S , Guo L J 
Published: November 2020

Abstract
Deep mining is an inevitable future trend involving resource acquisition. However, as mining depth increases, the high geostress and severe mining disturbance lead to prominent rock burst disasters. At present, the design of deep mines is mainly based on the engineering experiences based on shallow mining. To date, no integrated planning has been implemented for deep mining in domestic mines. Moreover, during the deep mining process, most problems are handled and solved only after the disaster happens due to the lack of understanding of deep disaster problem. In this paper, a large-scale 3D numerical model was established by Map3D software by considering the high geostress environment, the physical and mechanical parameters of rocks, the constitutive model, and preliminary design parameters Based on this model, the disturbance coefficient and energy accumulation state of stopes was predicted, and the rock burst risk was evaluated. According to the analysis results, the medium-deep hole sublevel open stopping method was chosen to reduce the rock burst risk during deep mining. Through the integrated planning of deep mining, the risk of rock burst disasters can be evaluated ahead of time, thus facilitating the use of a more scientific and reasonable mining method in the field of mining engineering. Integrated planning provides a new method for deep mining and can also and can help reduce or even control fundamentally the magnitude and frequency of rock burst disasters. Thus, it has great security and economic significance for mining engineering.
Overall Design and Optimization of Mining Sequence in High-Stress Environment of Thick Orebody
Authors: Shan WU , Xiaocong YANG , Lijie Guo , Lu CHEN 
Published: November 2020

Abstract
After entering deep mining, the stress concentration level because of engineering excavation is considerably greater than the strength of the engineering rock mass. Here, we consider the engineering impact of a high stress environment in the deep mine plan, integrate the high-stress environment and its evolution with the mining process into the mining plan, and realize the balance of improving the stress state and getting the maximum net present value. Using Map3d boundary element simulation software, we planned two vertical and four horizontal mining sequences for deep and thick orebody backfill mining, respectively, and then analyzed the changes in stress and rock mass energy because of mining disturbance. The results show that the surrounding mining sequence can effectively improve the mining stress environment and increase production capacity. Using large-spaced dispersion and mining sequence from the middle to both ends can gradually redistribute the stress to adjacent areas, thus reducing the degree of stress concentration.
Study of the frequency response of the block–rock mass with bimodulus characteristics
Authors: Jiang Kuan , Qi Cheng-zhi , Zhu Shou-dong , Jin Tian-wei 
Published: November 2020

Abstract
The pendulum-type wave phenomenon is a unique mechanical phenomenon in deep rock mass. It propagates at low frequencies and low speeds in the rock mass, and can cause deep rock engineering disasters such as rockbursts. For determining the low-frequency characteristics of a pendulum-type wave, the frequency response of the pendulum-type wave in block-rock mass with bimodulus characteristics is studied under a half-sine impact load. The dynamic pendulum-type wave model in a block–rock mass is used to determine the low frequency characteristics of the wave. The improved central difference method is applied, and the influence of the modulus ratio on frequency response is analyzed. Furthermore, the natural frequency of the system is inverted, through the frequency response of the block, and its correctness is verified. The results show that a decrease in the modulus ratio causes an obvious increase in the number of frequency response peaks of the block. The amplitude of the frequency response peaks decreases and the position of peaks moves to a low frequency range. The low-frequency characteristics of the pendulum-type wave in the block–rock mass with bimodulus characteristics are more obvious. The natural frequency of the system can be inverted by the fact that it corresponds to the peak frequencies of the frequency response. This approach provides a new method for the determination and measurement of the natural frequency of nonlinear systems.
Characteristics of Roof Movement and Ground Pressure Behavior of Gob-side Entry Retaining by Roof Cutting in Continuous Mining
Authors: Li Minzu , Ma Zimin , Wang Haohao , Zhang Yong , Jia Fayuan 
Published: November 2020

Abstract
Gob-side entry retaining by roof cutting (GERRC) technology has been widely used in China, but application research of the entry-retaining technology in continuous mining is relatively scarce. Based on the analysis of the technology of continuous mining and GERRC, this study adopted the methods of theoretical analysis and in-field monitoring of ground pressure and behavior to obtain the roof movement characteristics and ground pressure distribution law during the entire process of roof directional pre-splitting, entry retaining, and entry reusing. Using the engineering geological conditions and analysis of field data of Dianping coal mine in Shanxi Province, the principal design parameters and technological process of GERRC in continuous mining were obtained. The structure model of the retained roadway roof in continuous mining was constructed to study roof movement patterns and the mechanism of stability control of the retained roadway. The movement regularity of the overlying strata in the mining and entry-retaining stage was obtained, enriching the theory of roof structure evolution and stress transfer under the condition of continuous mining with GERRC. The research results provide significant support for further popularization and application of the technology of GERRC.
Stress characteristics and control of coal and rock in steeply dipping coal seam mining under the goaf of a close coal seam group: a case study
Authors: Fu Qiang , Yang Ke , Liu Qinjie , Chi Xiaolou 
Published: November 2020

Abstract
Steeply dipping coal seams, which are widespread in western China, are considered to have complex mining conditions. The development of such a seam plays an important role in regional economic development. Some steeply dipping coal seams are distributed at close distances. For closely located coal seam groups, China generally adopts the downward mining method for mining. Aiming at the problems of the appearance of ground pressure such as coal wall spalling and roadway squeezing deformation of a fully inclined working face under a goaf in a close coal seam group, the mining of the 5th and 4th coal at the steeply dipping coal seam in Panbei Mine was established as the engineering background. The mechanical model of the coal zone plastic area in front of the 12124 working face under the goaf and the distribution characteristics of abutment pressure in front of the coal wall were obtained. The working surface layout and coal rock physical and mechanical parameters were derived based on field observation records and indoor rock mechanics experiments. A numerical analysis model based on the fast Lagrangian analysis of Continua 3D software was constructed, and the surrounding rock mechanics during the 12124 working face mining process was simulated. The stress distribution characteristics of the front and back of the 12124 working face under the goaf were obtained, magnitude and location of the stress peak were determined, and superposition mechanism of the support pressure evolution of the fully mechanized thick seam under the goaf was revealed. Through field measurement of the distribution of the working resistance of the supports, the maximum working resistance, position of the supports, and accuracy of the theoretical calculation and numerical simulation were verified within the error range. Furthermore, stability control technology of the surrounding rock of the stope, roof falling, and roadway under this condition was proposed and implemented. Good economic and technical effects were obtained, which ensured safe mining at these working faces.