bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of granule size distribution on the compaction property of GMZ bentonite
Authors: Xie J L , Liu Y M , Cao S F 
Published: November 2020

Abstract
In the current concept for disposal of high-level radioactive waste (HLW) in China, a barrier composed of blocks of highly compacted bentonite is constructed around the waste canisters. To develop this technique, uniaxial compaction of full-sized bentonite blocks has been initiated. Many factors affect the quality of bentonite blocks, including water ratio and granule size distribution of the bentonite, compaction pressure and rate, and form geometry. In the present study, compaction tests were conducted using powdered, pelleted, and mixed GMZ bentonite to evaluate the effects of granule size distribution on the integrity and uniformity of the block samples. Results show that high-quality blocks can be manufactured by adjusting the water content of the bentonite to 17%, in spite of different granule size distributions. The compaction in the mixed bentonite was better than that in the powdered and pelleted samples. However, the difference in final density was negligible when compacting at the same pressure. The block uniformity was not improved by adopting different granule size distributions when the height:diameter ratio of the bentonite samples reached 2. Blocks produced by powdered and mixed bentonite were prone to radial cracks when subjected to moisture loss; however, the cracks were healed after moisture redistribution.
Energy storage and dissipation characteristics of red sandstone in triaxial compression tests under constant confining pressure
Authors: Li Liuliu , Gong Fengqiang 
Published: November 2020

Abstract
To investigate the energy storage and dissipation characteristics of rock material in triaxial compression tests under constant confining pressure, a series of triaxial single-cyclic loading–unloading compression tests were conducted on red sandstone specimens under eight confining pressures. Using the method of graphic area integration, the input energy density, elastic energy density, and dissipative energy density of the specimen in axial, circumferential, and total directions were obtained. The results indicate that the input energy density in the axial direction accounts for the largest logarithmic proportion of the total input energy density and that the relationship between all the parameters of the energy density and the unloading level can be described by the quadratic function. In the axial direction, a linear function relationship exists among elastic, dissipative, and input energy densities. In the circumferential direction, a quadratic function relationship exists among elastic, dissipative, and input energy densities. For the total energy parameters of the sample, the relationship of elastic, dissipative, and input energy densities conforms to the quadratic function, providing a new method for the accurate estimation of the energy parameters in the rock under high stress.
Evaluation methods and standards for rock drillability in oil and gas drilling engineering in China: A review
Authors: Shi Xiangchao , Wu Jie , Gao Leiyu , Chen Shuai , Li Gao 
Published: November 2020

Abstract
In western China, 70% of the oil, gas, and geothermal resources are buried in deep formations (more than 3000 m), but the low rate of penetration has become a key factor restricting the development of these resources. Rock drillability evaluation is a basic task for oil, gas, and geothermal drilling engineering design that includes bit design, bit selection, and drilling parameter optimization. Different tests and standards to evaluate rock drillability have been developed worldwide. Against this backdrop, the evaluation methods and standards for rock drillability are reviewed. Various rock drillability tests and classification standards are compared and analyzed. Results show that these methods and standards are inaccurate and fail to meet the design requirements of drilling technology and bit selection in deep and ultradeep drilling wells. In China, micro-drilling test is commonly used to evaluate rock drillability in oil and gas drilling engineering. This method was developed as an oil and gas industry standard and has been used for more than 40 years. However, its results do not reflect the significant effects of high temperature and pressure at the bottom hole on rock drillability and breaking; thus, the results cannot be used in drilling designs. Testing methods and classification standards for rock drillability require innovative developments. This review highlights the following: (1) the classification standards for rock drillability must be refined in the future to meet the requirements of drilling designs in deep and ultradeep wells; (2) efficient and fast rock drillability tests are required to deal with complex and difficult formations; (3) the influence of the real physical environment of the borehole bottom on rock drillability must be further clarified.
Slurry Infiltration Column Tests on Saturated Sand
Authors: Zhuang X Y , Zhang Z X , Huang X , Yin T 
Published: November 2020

Abstract
Slurry infiltration process contributes to the stability of tunnel face significantly during slurry shield tunneling construction. The support pressure cannot be transmitted efficiently to the face unless a compact filter cake forms. This paper aims at investigating the formation of filter cake in saturated sand by slurry infiltration column tests. A series of tests were performed under different filtration pressures using three concentrations of slurry in four types of saturated sand stratums. In order to obtain the characters of the infiltration process and filter cake, pore pressure evolution was measured. Three types of filter cakes were observed in the tests, including external filter cake, external filter cake plus internal filter cake and deep infiltration. External filter cake transmits support pressure efficiently, while the other two types of filter cakes cannot provide sufficiently support pressure for the tunnel face. Especially, deep infiltration behaves no capacity of retaining pressure and should be avoided in engineering practice.
Experimental study on the prediction model of the cumulative strain of the soil–rock mixture backfill under metro train load
Authors: Zhong Z L , Xu Y W , Hu X X , Liu X R , Du L B 
Published: November 2020

Abstract
An indoor dynamic triaxial test was performed on the soil–rock mixture (SRM) backfill in Chongqing to study the cumulative strain characteristics of the SRM under the cyclic dynamic loading of the metro train. The effects of different consolidation degrees U, rock block contents P, and effective consolidation confining pressures

σ
3
′

were then analyzed. Results showed that when

σ
3
′

and P are the same, the lower the U, the faster will be the increase in cumulative strain. When U and P were the same, the lower the

σ
3
′

, the greater will be the increase in cumulative strain and the higher will be the cumulative strain stable value of the stability curve. When U and

σ
3
′

were the same, the lower the P, the faster will be the increase in cumulative strain. An empirical model of the cumulative strain of the SRM considering the influence of U, P, and

σ
3
′

was established on the basis of the results of the dynamic triaxial tests. The accuracy of the prediction model was verified against the actual test results. This study provides a theoretical basis for the settlement and deformation evaluation of SRM backfill subgrades under metro train cyclic loading.
Large physical simulation and optimum parameter determination of stimulated reservoir volume (SRV) of a tight reservoir in E’nan
Authors: Xiao Yang , Zhang Liying , Li Zhigang , He Wen , Liu Zilong , Liu Shouyu 
Published: November 2020

Abstract
Studies have demonstrated that the real hydrofracturing in fractured reservoirs will not all form symmetrical fracturing in classical theory; however, they will rather form a complex fracture network. The changes in geostress because of the existence of natural fractures are an important reason for this phenomenon. At present, there are systematic theories and methods for examining the extension of hydraulic fractures after intersecting with natural fractures. Moreover, there is little or no quantitative research on specific parameters reported in the literature. However, the results are not applicable to actual field exploitation. Based on previous studies, this study proposes an improved model for hydraulic fractures after intersecting with natural fractures. Using the Honghe 92 well area in E’nan reservoir as the test case, the intersection chart of the block was drawn to analyze the extended model of hydraulic fracture. In this study, the true triaxial physical simulation experiment is reported and a comparison was made to demonstrate the correctness of the intersection chart. The fracturing simulation of Honghe 92 well area in E’nan reservoir was conducted to optimize the construction parameters and construction suggestions were put forward for the well area. The research results provide a theoretical basis and parameter guidance for the actual exploitation design of the oilfield. Furthermore, the results obtained will be helpful in improving the effect of SRV and increase oilfield productivity.
In situ Stress Measurement in Kilometer-Deep Mine and Its Relationship with Minefield Fault Structure
Authors: Zhongcheng QIN , Wang NIE , Litian SUN , Bin CAO , Lining LIU , Dengyue LI 
Published: November 2020

Abstract
In view of the complicated geological stress structure and fuzzy distribution characteristics of a kilometer-deep mine, the KX-81 hollow inclusion stress relief method was used to test in situ stress in Shuanghe Coal Mine at the level of –1100. On the basis of the field test data, the 3D grid diagram of the principal stress distribution in the deep mining area of Shuanghe Coal Mine was drawn, and the relationship between the in situ stress distribution characteristics and the fault structure in wellfield was studied. Results showed that 1) the directions of σ1 and σ3 at each measurement point were horizontal, and the other principal stress σ2 was vertical. 2) The maximum principal stress value was 1.26–1.48 times of the self-weight stress value, indicating that the horizontal tectonic stress plays a leading role in the in situ stress of the mine. 3) The horizontal and vertical stresses at a depth of about 1090 m were estimated according to the theory. A comparison revealed that the theoretical values were lower than the field measured values. The area was found to be dominated by horizontal tectonic forces belonging to the dynamic stress field. 4) The direction of σ1 at each measurement point was 114.70°–124.72°, with an average of 120°. The direction was NWW-SEE. In accordance with the distribution law of the fault structure in the wellfield, the consistency between the wellfield geological structure and the measured direction of the maximum principal stress was analyzed and verified. The research results provide technical basis for deep well roadway layout and stability control and improve the scientific nature and reliability of surrounding rock control of high stress roadway in deep wells under complex geological structures.
Hydraulic characterization of fault F31 at the Xinchang underground research laboratory site for geological disposal of high-level radioactive waste
Authors: Ji Ruili , Su Rui , Zhang Ming , Zhao Jingbo , Zhou Zhichao , Li Jiebiao 
Published: November 2020

Abstract
As part of the suitability evaluation of the underground research laboratory (URL) candidate sites, the hydrogeological investigation activity was conducted at the Xinchang site in Beishan area from 2016 to 2019. A previous study discovered that the rock masses at the Xinchang URL site, which is surrounded by north–east trend and east–west faults, have low permeability and shortage of water-bearing structures. This article aimed to describe the hydraulic properties of fault F31, which is located on the west boundary of the Xinchang URL site, and evaluate the fault hydraulic characterization methodology for site characterization of the URL and repository sites.
The surface hydrology monitoring activity at the Xinchang site showed that the water flow occurring through the gully where fault F31 is located after precipitation is the main recharge resource of groundwater. Accompanied with hydraulic monitoring during the drilling period of inclined boreholes (BSQ04–BSQ06, BS35, and BS36) crossing fault F31, the survey revealed that groundwater was stored in the weathered zones of the middle and north parts along fault 31. Single-hole and interference tests were performed later with the Heavy-Duty Double Packer system. The hydraulic conductivity (K) and storativity (S) were interpreted from the test data using analytical solutions. Diagnostic plots were also used in determining the reliability of results and identifying the flow regime. By considering the interpretation of borehole acoustic television logging as reference, the spatial morphological statistics of the structures are mainly parallel with the fault plane, wherein K is lower than 1 × 10−9 m/s depth to −250 m below the surface. Thus, the strike-dip parameter of the water resistance structures can be roughly confirmed. Six sections were selected for the evaluation of the water-conductive structures; these sections exhibited depths of more than −250 m below the surface and K values of equal to or more than 1 × 10−9 m/s. After the structures with a strike-dip similar to that in the water-resistant sections were removed, the remaining structural planes were used to build a flow model path during the hydraulic test. Compared with flow regime derived from the diagnostic plots, the structural planes fitting the real flow regime were identified as water-conductive structures.
The results showed the following: (1) K and S increased from the south to the north in the shallow zone along fault F31, where water-conductive structures were surrounded by water-resistant structures; (2) the section located −250 m below the surface of F31 was water resistant, and no-flow channel existed in the deformation zone along fault F31; and (3) the fault hydraulic characterization methodology combining hydraulic test, hydrological survey, and geophysical logging is suitable for the site characterization of URL and repository.
Deep borehole in situ stress measurements by hydraulic fracturing method in Xuefengshan area
Authors: Yang Yuehui , Sun Dongsheng , Meng Wen , Li A-wei , Wang Bin , Chen Qunce 
Published: November 2020

Abstract
The in situ stress state is a key parameter for shale gas exploration and geodynamics. To obtain the ultra-depth stress state of the Xuefengshan area, the hydraulic fracturing in situ stress method was employed in this study to determine the stress state at a depth range of 170–2021 m. The test results, which are the first reported for borehole depth greater than 2000 m in China, show that the magnitude of the in situ stress increases with the depth of the borehole. At a depth of 2021 m, the measured maximum and minimum horizontal principal stresses were 66.31 MPa and 43.33 MPa, respectively. The linear fitting relationships between the maximum and minimum horizontal principal stresses with the depth of the test borehole were SH = 0.033999D + 5.9996 and Sh = 0.020729D + 4.8058, respectively. In the borehole depth range of 170–800 m, the relationships of the three principal stresses were SH > Sh > SV, which is favorable for reverse faulting. At borehole depths of 1000–2021 m, the relationships changed to SH > SV > Sh, which implies that the deep stress regime of this area is strike-slip faulting.
Liquid-filling auxiliary device for liquid-filled rock joints and its application
Authors: Huang J , Song D Q , Liu X L , Zhao J , Wang E Z , Wang S J 
Published: November 2020

Abstract
Filling joints are relatively common in rock mass-based geotechnical engineering. Presently, many researchers have concentrated on the analysis of filling joints with a solid or solid–liquid mixture as filling materials, while only few scholars have been investigating the filling conditions of liquid. In this study, a liquid-filling auxiliary device was developed. The primary test flow on a typical sample and its application in dynamic response to filling liquid were introduced. Granite and plexiglass were selected as test samples to emulate the structure of liquid-filled jointed rock mass, and a split Hopkinson pressure bar was employed for dynamic testing of the structure. The test results reveal that during data collection, pressure response of the filling liquid suddenly rises, experiences multiple fluctuations, and then gradually stabilizes. With an increase in the initial thickness of the filling liquid, peak value of the liquid pressure change exhibited an increasing trend. Further, dynamic response characteristics of filling liquid in liquid-filled jointed rock mass were analyzed. The outcomes provide a reference for the experimental study on the interaction mechanism between the stress wave and jointed rock mass and liquid.
SPH-FEM coupling simulation of rock blast damage based on the determination and optimization of the RHT model parameters
Authors: Wang Z L , Huang Y P , Li S Y , Xiong F 
Published: November 2020

Abstract
To improve the accuracy of the results of rock blast damage simulation, a numerical scheme of ascertaining and optimizing the Riedel–Hiermaier–Thoma (RHT) model parameters was developed. First, the RHT model was adopted to simulate limestone penetration experiments, and the 31 RHT model parameters were initially determined based on the published data and theoretical derivation. Subsequently, sensitivity analyses were conducted using the “controlled variable method” to optimally determine the parameters. Finally, the RHT model parameters and coupled smoothed-particle hydrodynamics (SPH)-finite element method (FEM) were employed to simulate the limestone blast damage. The results demonstrate that the relative sensitive parameters obtained by taking the penetration depth of the projectile as the investigation index are ρ
0, ρ
s, p
e, G, f
ϕ, B, M, and F
G. The proposed “constant-amplitude adjustment method” can guarantee the integrity of the parameter ascertainment to a certain extent. The blast simulations indicate that the RHT model parameters determined based on the penetration experiment have certain applicability for the blast simulation and that the coupled SPH-FEM algorithm has a great advantage over FEM or SPH and can realistically show the whole process of rock blasting.
Karst development characteristics and collapse risk assessment along Shaoxing metro line 1
Authors: Huang Jiandong , Xue Fei , Wang Tianzuo , Zhao Tongyang , Wang Xiaoyu 
Published: November 2020

Abstract
Urban subway construction in karst areas can be seriously threatened by geological disasters, which impact the safety of subway construction and operation. Given the effects of geological conditions and human engineering activities, it is necessary to comprehensively analyze the influence of various factors and then evaluate the risk of karst collapse. With the section between Yanghe road station and Jianhu town station of Shaoxing metro line 1 as an example, crosshole seismic wave computed tomography (CT) was employed to prospect the geometric characteristics and spatial distribution of karst caves. Based on the survey results, ten influencing factors were selected as evaluation indexes for karst collapse susceptibility. Then, an assessment system was established, and each index was quantitatively rated through three grades. The analytical hierarchy process was used to determine the weight of these indexes, and the fuzzy transform principle and maximum membership degree principle were applied to quantitatively and comprehensively evaluate the collapse risk level in the study area. Results showed that karst cave development mainly occurred in the bedrock surface under 11 m. The caves were mostly 2–5 m high, and most of them were filled. Approximately 70% of the studied section had a moderate or high risk of karst collapse. As the subway passes through the karst area, appropriate measures should be implemented for the different risk sections to ensure the safety of construction and operation.
Risk assessment of Sichuan–Tibet Highway susceptible to debris flows at Suotong Basin, southeastern Tibet
Authors: Hu Kaiheng , Wang Xiaodong , Liu Jinfeng , Wang Zhang , Tang Jinbo , Zhong Wei 
Published: November 2020

Abstract
The planned Sichuan–Tibet Highway will pass through many debris flow-prone areas. Suotong catchment with a drainage area of 38.03 km2, a tributary of Parlung Zangbo River in the Bomi County of Tibet, has not experienced large-scale debris flows since 1991. Field survey and image interpretation show that glacial till in the catchment has volume of approximately 160 mm3 and is the primary source of loose materials for debris-flow reoccurrence. Once large glacial debris flows occur, they will cause harm to the highway. A comprehensive method including engineering geology, hydraulics, and computational mathematics is developed to quantitatively assess the debris-flow risk to the highway. The magnitude and peak discharge of glacial debris flows of a 100 year return period are calculated using empirical relationships in this region. The peak velocity at the outlet can reach 6.75 m/s, and the peak discharge is 6238 m3/s for such a return period. The Saint–Venant equations governing debris-flow movements are numerically solved by finite difference method. The simulated results are close to those by empirical methods. The hazard value at the alluvial fan is as high as 24.7 according to the numerical simulation. Two routing schemes (one goes through the tunnel and other pass the bridge) are compared with each other. Although the bridge scheme is cheaper than the tunnel scheme, the bridge’s section cannot fully discharge debris flows within the 100-year return period. Therefore, the tunnel scheme is safer and more strongly recommended than the bridge scheme.
The development of China national geohazard information system
Authors: Tong Bin , Li Yuan , Yang Xudong , Yin Chunrong , Qu Xueyan , Fang Hao , Han Bing , Zhang Yanling 
Published: November 2020

Abstract
Geohazards caused significant damages to people and economical properties. The prevention and mitigation of geohazards in China is facing great challenges. To solve the problem, establishing a national geohazard information system is important in accessing the distribution of geohazards, optimizing the efforts of prevention and mitigation, and improving the public awareness and risk reduction capabilities. After two decades’ of development, China national geohazard information system have upgraded from client-server (C/S) to browser-server (BS) architecture, and now to the micro-service based architecture, more than 320 thousands of geohazards which were mainly collected through field surveys and the routine field inspections have been saved in the database; through the information system, data acquisition and integration, classified storage, efficient data processing, real-time statistics and data services have been achieved and standardized by numerous technical specifications. In this paper, the current status of China national geohazard information system, including the development progress, database architecture, system functionality and data applications are introduced, and expected to provide references of establishing an efficient and comprehensive geohazard information system to improve the geohazard risk reduction capabilities for the countries or regions suffering from geohazards.