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Study on influence of key blasthole parameters on tunnel overbreak

Underground Space 2023年第2期9卷 76-90页

作者： Zi-qiang Li Zheng Li Wei-wei Huang xuan-ming ding Hang Zhang School of Civil Engineering and Architecture Chongqing University of Science&TechnologyChongqing 401331China Key Laboratory of New Technology for Construction of Cities in Mountain Area Ministry of EducationChongqing UniversityChongqing 400045China Chongqing City Construction Investment(Group)Co. Ltd.Chongqing 400023China School of Civil Engineering Chongqing University400045China

To determine the influence of key blasthole parameters on tunnel overbreak during blasting construction,an intelligent detection sys-tem for tunnel blasting construction is independently *** the key blasthole parameters and overbreak of a typical section of a single line tunnel under the condition of Class V surrounding rock are analyzed and *** actual data obtained is compared with the results of numerical simulations and theoretical *** results are as follows:(1)Quantitative analysis is performed based on the blasthole angle,opening position,and charge mass by the self-developed intelligent detection equipment for blasthole parameters,which can be used to guide the drilling *** scanning equipment for outline excavation can be used to image the actual excavation section in real-time and has the advantages of high precision and fast speed;(2)Tunnel overbreak can be regarded as consisting of two parts:the surrounding rock damage caused by the blasting load,and the collapse of the surrounding rock caused by the blasthole opening *** parameter of the peripheral hole will affect the tunnel overbreak;however,the key parameter is the blasthole opening position;(3)The distributions of the tunnel overbreak volume obtained with the theoretical analysis,finite element simulation,and measurements are basically *** the condition of Class V surrounding rock,the overbreak of this single line tunnel can reach 14.1–78.2 *** meet the specification requirements,the opening position and construction accuracy of the peripheral hole should be strictly controlled.

关键词： Tunnel blasting Blasthole parameters Tunnel overbreak Surrounding rock damage Smooth surface blasting

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Interface characteristic and mechanical performance of TiAl/Ti_(2)AlNb diffusion bonding joint with pure Ti interlayer

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Rare Metals 2020年第12期39卷 1402-1412页

作者： Lei Zhu Bin Tang ming-xuan ding Yan Liu Xiao-Fei Chen Shao-Peng Yan Jin-Shan Li State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi'an 710072China Shaanxi Key Laboratory of High-Performance Precision Forming Technology and Equipment Northwestern Polytechnical UniversityXi'an 710072China

Solid-state diffusion bonding(DB)of TiAl alloy and Ti2 AlNb alloy was carried out using pure Ti as an interlayer at 1000℃under 20 MPa for 60-120 *** effects of bonding times on the interfacial microstructure and mechanical performance of the TiAl/Ti/Ti_(2)AlNb bonded joints at room temperature(RT)were investigated *** results demonstrated that the diffusion layers(DLs)mainly consisted of four characteristic layers,(Ⅰ)single coarseα_(2)phase adjacent TiAl alloy,(Ⅱ)single refinedα_(2)phase at the bonding interface,(Ⅲ)equiaxed/acicularα_(2)phase embedded inβphase adjacent Ti_(2)AtNb alloy and(IV)both equiaxedα_(2)phase and acicular O phase embedded inβphase adj acent Ti_(2)AlNb alloy,*** thickness of the four layers increased with the increasing of the bonding *** growth of DLs is controlled by diffusion and the reaction rate constant k for regionⅠ,Ⅱ,ⅢandⅣare 1.22×10^(-6),1.27×10^(-6),2.6×10^(-7)and 7.7×10^(-7)m·s^(-1/2),***,the interfaceα_(2)grain grows up without *** maximum tensile strength of 281 MPa was maintained at1000℃for 90 min under the pressure of 20 ***,the phase transformation and dynamic recrystallization behavior of the DLs were discussed.

关键词： Sputtering Bonding interface Microstructure Growth kinetics Mechanical performance

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Application of transparent soil model tests to study the soil-rock interfacial sliding mechanism

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Journal of Mountain Science 2019年第4期16卷 935-943页

作者： WANG Zhuang LI Chi ding xuan-ming Department of Civil Engineering Inner Mongolia University of Technology Key Laboratory of New Technology for Construction of Cities in Mountain Area Ministry of Education Chongqing University

When transparent soil technology is used to study the displacement of a slope, the internal deformation of the slope can be visualized. We studied the sliding mechanism of the soil-rock slope by using transparent soil technology and considering the influence of the rock mass Barton joint roughness coefficient, angle of the soil mass, angle of the rock mass and soil thickness factors on slope stability. We obtained the deformation characteristics of the soil and rock slope with particle image velocimetry and the laser speckle technique. The test analysis shows that the slope sliding can be divided into three parts: displacements at the top, the middle, and the bottom of the slope; the decrease in the rock mass Barton joint roughness coefficient, and the increase in soil thickness, angles of the rock mass and soil mass lead to larger sliding displacements. Furthermore, we analyzed the different angles between the rock mass and soil thickness. The test result shows that the displacement of slope increases with larger angle of the rock mass. Conclusively, all these results can help to explain the soil-rock interfacial sliding mechanism.

关键词： Slope engineering Transparent soil Model test Interfacial sliding mechanism

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Dynamic Behavior of Gravity Retaining Walls with Coral Sand Backfill Under Earthquakes:Shaking Table Tests

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China Ocean Engineering 2022年第6期36卷 839-848页

作者： ZHANG Yan-ling WANG Cheng-long ding xuan-ming WU Qi College of Civil Engineering Taiyuan University of TechnologyTaiyuan 030024China Key Laboratory of New Technology for Construction of Cities in Mountain Area School of Civil EngineeringChongqing UniversityChongqing 400045China

The retaining walls in coral sand sites are inevitably threatened by earthquakes. A series of shaking table tests were carried out to study the seismic stability of gravity retaining walls with coral sand backfill. Parallel tests with quartz sand were performed to compare and discuss the special dynamic properties of coral sand sites. The results show that the acceleration difference between the retaining wall and the coral sand backfill is 76%-92% that of the quartz sand,which corresponds to the larger liquefaction resistance of coral sand compared with the quartz sand. However, the horizontal displacement of the retaining walls with coral sand backfill reaches 79% of its own width under 0.4g vibration intensity. The risk of instability and damage of the retaining walls with coral sand backfill under strong earthquakes needs attention.

关键词： coral sand seismic response liquefaction shaking table test gravity retaining walls

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Chondroitinase ABC combined with Schwann cell transplantation enhances restoration of neural connection and functional recovery following acute and chronic spinal cord injury

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Neural Regeneration Research 2025年第5期20卷 1467-1482页

作者： Wenrui Qu Xiangbing Wu Wei Wu Ying Wang Yan Sun Lingxiao Deng Melissa Walker Chen Chen Heqiao Dai Qi Han Ying ding Yongzhi Xia George Smith Rui Li Nai-Kui Liu Xiao-ming Xu Spinal Cord and Brain Injury Research Group Stark Neurosciences Research InstituteDepartment of Neurological SurgeryIndiana University School of MedicineIndianapolisINUSA Department of Hand Surgery the Second Hospital of Jilin UniversityChangchunJilin ProvinceChina Shriners Hospitals Pediatric Research Center Temple University School of MedicinePhiladelphiaPAUSA Department of Anatomy&Cell Biology Indiana University School of MedicineIndianapolisINUSA

Schwann cell transplantation is considered one of the most promising cell-based therapy to repair injured spinal cord due to its unique growth-promoting and myelin-forming properties.A the Food and Drug Administration-approved Phase I clinical trial has been conducted to evaluate the safety of transplanted human autologous Schwann cells to treat patients with spinal cord injury.A major challenge for Schwann cell transplantation is that grafted Schwann cells are confined within the lesion cavity,and they do not migrate into the host environment due to the inhibitory barrier formed by injury-induced glial scar,thus limiting axonal reentry into the host spinal *** we introduce a combinatorial strategy by suppressing the inhibitory extracellular environment with injection of lentivirus-mediated transfection of chondroitinase ABC gene at the rostral and caudal borders of the lesion site and simultaneously leveraging the repair capacity of transplanted Schwann cells in adult rats following a mid-thoracic contusive spinal cord *** report that when the glial scar was degraded by chondroitinase ABC at the rostral and caudal lesion borders,Schwann cells migrated for considerable distances in both rostral and caudal *** Schwann cell migration led to enhanced axonal regrowth,including the serotonergic and dopaminergic axons originating from supraspinal regions,and promoted recovery of locomotor and urinary bladder ***,the Schwann cell survival and axonal regrowth persisted up to 6 months after the injury,even when treatment was delayed for 3 months to mimic chronic spinal cord *** findings collectively show promising evidence for a combinatorial strategy with chondroitinase ABC and Schwann cells in promoting remodeling and recovery of function following spinal cord injury.

关键词： axonal regrowth bladder function chondroitinase ABC functional recovery glial scar lentivirus migration Schwann cell spinal cord injury transplantation

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Large scale synthesis of full-color emissive carbon dots from a single carbon source by a solvent-free method

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Nano Research 2022年第4期15卷 3548-3555页

作者： Hui ding xuan-xuan Zhou Zi-Hui Zhang Yun-Peng Zhao Ji-Shi Wei Huan-ming Xiong Key Laboratory of Coal Processing and Efficient Utilization of Ministry of Education and College of Chemical Engineering China University of Mining and TechnologyXuzhou 221116China Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Fudan UniversityShanghai 200433China

Full-color emissive carbon dots(CDs)hold a great promise for various applications,especially in light emitting diodes(LEDs).However,the existing synthetic routes for CDs are carried out in solutions,which suffer from low yields,high pressures,various byproducts,large amounts of waste solvents,and complicated photoluminescence(PL)***,it is necessary to explore large scale synthesis of CDs with high quantum yield(QY)across the entire visible range from a single carbon source by a solvent-free *** this work,a series of CDs with tunable PL emission from 442 to 621 nm,QY of 23%-56%,and production yield within 34%-72%,are obtained by heating o-phenylenediamine with the catalysis of *** characterizations identify that,the differences between these CDs with respect to the graphitization degree,graphitic nitrogen content,and oxygen-containing functional groups,are responsible for their distinct optical properties,which can be modulated by controlling the deamination and dehydrogenation processes during ***,green,yellow,red emissive films,and LEDs are prepared by dispersing the corresponding CDs into polyvinyl alcohol(PVA).All types of white LEDs(WLEDs)with high colorrendering-index(CRI),including warm WLEDs,standard WLEDs,and cool WLEDs,are also fabricated by mixing the red,green,and blue emissive CDs into PVA matrix by the appropriate ratios.

关键词： carbon dots solvent-free synthesis full-color luminescence surface state white light emitting diodes

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Bearing Behavior of Cast-in-Place Expansive Concrete Pile in Coral Sand Under Vertical Loading

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China Ocean Engineering 2021年第3期35卷 352-360页

作者： ding xuan-ming DENG Wei-ting PENG Yu ZHOU Hang WANG Chun-yan Key Laboratory of New Technology for Construction of Cities in Mountain Area Chongqing UniversityChongqing 400045China National Joint Engineering Research Center of Geohazards Prevention in the Reservoir Areas Department Chongqing UniversityChongqing 400045China College of Civil Engineering Chongqing UniversityChongqing 400045China

The low side friction of piles in coral sand results in the low bearing capacity of *** this paper,expansive concrete pile is utilized to improve the bearing capacity of pile foundations in coral *** model tests and numerical simulation are performed to reveal the bearing mechanism of expansive concrete pile in coral *** showed that the lateral earth pressure near pile increases obviously and the side friction of piles is improved,after adding expansion agent to the *** horizontal linear expansion is 1.11%and the bearing capacity increased 41%for the pile,when 25%expansion agent is *** in finite element numerical simulation also show that ultimate bearing capacity increases with the increase of the linear expansion ***,the area for obvious increase in side friction is below the surface of soil about three times the pile diameter,and the expansion leads to a high side friction sharing of the ***,the cast-in-place expansive concrete pile is effective in improving the bearing capacity of piles in coral sand.

关键词： bearing behavior expansive concrete pile coral sand side friction numerical simulation

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Effects of topography on dynamic responses of single piles under vertical cyclic loading

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Journal of Mountain Science 2020年第1期17卷 230-243页

作者： QU Li-ming ding xuan-ming WU Chong-rong LONG Yong-hong YANG Jin-chuan College of Civil Engineering Chongqing UniversityChongqing 400045China Key Laboratory of New Technology for Construction of Cities in Mountain Area Chongqing UniversityChongqing 400045China Citation:Qu LMDing

This paper describes model tests of single piles subjected to vertical cyclic compressive loading for three kinds of topography: sloping ground, level ground, and inclined bedrock. Comprehensive dynamic responses involving cyclic effects and vibration behaviours are studied under various load combinations of dynamic amplitude, mean load,frequency and number of cycles. Test results show that permanent settlement can generally be predicted with a quadratic function or power function of *** ground topography produces more pronounced settlement than level ground under the same load condition. For vibration behaviour,displacement amplitude is weakly affected by the number of cycles, while load amplitude significantly influences dynamic responses. Test results also reveal that increasing load amplitude intensifies nonlinearity and topography effects. The strain distribution in a pile and soil stress at the pile tip are displayed to investigate the vibration mechanism accounting for sloping ground effects. Furthermore, the dynamic characteristics among three kinds of topography in the elastic stage are studied using a three-dimensional finite method. Numerical results are validated by comparing with experimental results for base inclination topography. An inclined soil profile boundary causes non-axisymmetric resultant deformation, though a small difference in vertical displacement is observed.

关键词： Pile Model test Dynamic response Permanent settlement Vibration displacement Topography effects

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Construction of atomic-level charge transfer channel in Bi_(12)O_(17)C_(l2)/MXene heterojunctions for improved visible-light photocatalytic performance

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Rare Metals 2022年第7期41卷 2405-2416页

作者： Song-Song Cui xuan Liu Yin-Biao Shi ming-Ye ding Xiao-Fei Yang College of Science Nanjing Forestry UniversityNanjing 210037China

Exploring efficient co-catalysts to accurately steer the charge separation of semiconductor photocatalysts is highly desired yet remains ***,we tackle the significant challenge by in situ growing the Bi_(12)O_(17)C_(l2)photocatalyst onto two-dimensional(2D)Cl-terminated Ti_(3)C_(2)MXene to construct 2D/2D heterojunction of Bi_(12)O_(17)C_(l2)and Ti_(3)C_(2).Firstly,2D few-layered Ti_(3)C_(2)MXene with chlorine groups has been successfully syn-thesized by Lewis acidic etching strategy with subsequent ultrasonic *** grafting of chlorine terminations on the surface of MXene serves as nucleating centers and growth platform,resulting in the formation of strong interfacial bonds(Bi-Cl-Ti)between Bi_(12)O_(17)C_(l2)and Ti_(3)C_(2).These strong bonds can facilitate the separation and transfer of photo-generated charge carriers between Bi_(12)O_(17)C_(l2)photocatalyst and Ti_(3)C_(2)*** expec-ted,the photocatalytic degradation rate of Bi_(12)O_(17)C_(l2)/Ti_(3)C_(2)hybrids is 9.7 times higher than that of bare Bi_(12)O_(17)C_(l2)*** work not only exhibits a new design concept to effectively steer the charge separation for photocatalysis,but also gives a reference for constructing efficient MXene-based photocatalytic systems.

关键词： Photocatalysis Ti3C2 MXenes Cocatalyst Schottky junction Heterojunction Charge transfer channels

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Performance of X-Section Concrete Pile Group in Coral Sand Under Vertical Loading

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China Ocean Engineering 2020年第5期34卷 621-630页

作者： PENG Yu LIU Jia-yi ding xuan-ming FANG Hua-qiang JIANG Chun-yong College of Civil Engineering Chongqing UniversityChongqing 400045China Key Laboratory of New Technology for Construction of Cities in Mountain Area Chongqing UniversityChongqing 400045China CCTEG Chongqing Engineering Co. LtdGeotechnical Engineering InstituteChongqing 400042China

To reveal the bearing capacity of the X-section pile group in coral sand, a series of model load tests are *** testing results are presented as load-settlement curves, pile-soil stress ratios, distributions of side friction and axial force, and load-sharing ratio between side and tip resistances. The reliability and accuracy of the numerical simulation model are verified by comparing the results of the model test. Comparative analysis between X-section and circular section piles with the same cross-sectional area indicates that the bearing capacity of the X-section pile group is much larger than that of the circular pile group. The axial force of X-section piles is smaller while the peak skin friction is larger than that of circular piles at the same depth. The skin friction of the core pile is the largest,followed by the side pile and the corner pile is the smallest when the load is relatively small;however, it is converse when the load is larger than 10 k N. Compared with piles in silica sand, the pile in coral sand has a lower bearing capacity, and the sand breakage leads to the steep drop failure of pile foundation. Moreover, pile positions under the raft have less effect on the load-share differences among corner, side and core piles in coral sand. This study provides a reference for the construction of pile foundations in coral sand.

关键词： X-section pile group coral sand model test numerical analysis pile-soil stress ratio

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