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Experimental investigation of face instability for tunnels in sandy cobble strata

Underground Space 2023年第3期10卷 199-216页

作者： Qiguang Di Pengfei Li Mingju Zhang xiaopu cui Key Laboratory of Urban Security and Disaster Engineering Ministry of EducationBeijing University of TechnologyBeijing 100124China

In order to investigate the influence of face instability for tunnels with different burial depths in sandy cobble strata on earth pressure and the instability region,geomechanical model tests and numerical simulations were *** continuous excavation method was adopted to reduce the pressure of the soil bin and restore the real engineering *** pressure in three directions of the obser-vation section in front of the tunnel face was monitored during the tunneling of the *** of the lateral stress ratios at dif-ferent stages were also *** instability area of the shield tunnel face in sandy cobble strata with different burial depth ratios during the instability stage was obtained based on the change ratio of earth pressure and compared with existing *** earth pressure began to change when the excavation was one shield diameter away from the observation section,and when the excavation reached the observation section,the earth pressure decreased *** burial depth of shield tunnel in the sandy cobble strata has a significant impact on the evolution of soil arch and the size of the failure *** numerical simulation of the continuum medium cannot reflect the stress redistribution characteristics of the granular body like sandy cobble strata,and the failure area or stress distur-bance area obtained by the model test is larger than the numerical simulation *** methods have deviations in analyzing the failure area of shield tunnel face in sandy cobble *** provides not only guidance for shield tunnel excavation engineering in sandy cobble strata,but also a reference for the theoretical research on failure areas.

关键词： Geomechanical model test Sandy cobble strata Face stability Arching effect Shield tunnel

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Analytical solutions of limit support pressure and vertical earth pressure on cutting face for tunnels

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Underground Space 2023年第5期12卷 65-78页

作者： Pengfei Li xiaopu cui Junwei Xia Xinyu Wang Key Laboratory of Urban Security and Disaster Engineering Ministry of EducationBeijing University of TechnologyBeijing 100124China China Railway 19 Bureau Group Rail Traffic Engineering Co.LTD Beijing 101399China School of Civil Engineering Henan Polytechnic UniversityJiaozuo 454000China

This paper focuses on theoretical analytical models to calculate the limit support pressure and vertical earth pressure on the cutting face for *** failure zone is divided into two parts:a sliding failure zone and an upper loosen zone,and the limit support pressure calculation equation is *** verify the rationality of the theoretical model,it was compared with the existing theory,numerical simulation,and centrifugal test,and then the parameter analysis was carried *** results show that the results of this paper agree well with the existing theory,numerical simulation,and centrifugal *** inclination angle of the proposed mechanism is determined based on the results of the existing centrifuge test,and the recommended inclination angle is between 52°+φ/2 and 54°+φ/*** method is proven to be safe and *** can provide a theoretical basis for similar projects.

关键词： Instability and failure Excavation face stability Global method Soil arch effect Limit support pressure

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Calibration method of mesoscopic parameter in sandy cobble soil triaxial test based on PFC3D

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Frontiers of Structural and Civil Engineering 2023年第12期17卷 1924-1933页

作者： Pengfei LI xiaopu cui Yingjie WEI Junwei XIA Xinyu WANG Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education Beijing University of TechnologyBeijing 100124China China Railway 14th Bureau Group Co. Ltd.Jinan 250014China China Railway 19 Bureau Group Rail Traffic Engineering Co. Ltd.Beijing 101399China School of Civil Engineering Henan Polytechnic UniversityJiaozuo 454000China

This paper presents a rapid and effective calibration method of mesoscopic parameters of a threedimensional particle flow code(PFC3D)model for sandy cobble *** method is based on a series of numerical tests and takes into account the significant influence of mesoscopic parameters on macroscopic ***,numerical simulations are conducted,with five implementation ***,the multi-factor analysis of variance method is used to analyze the experimental results,the mesoscopic parameters with significant influence on the macroscopic response are singled out,and their linear relations to macroscopic responses are estimated by multiple linear ***,the parameter calibration problem is transformed into a multi-objective function optimization *** simulation results are in good agreement with laboratory results both qualitatively and *** results of this study can provide a basis for the calibration of microscopic parameters for the investigation of sandy cobble soil mechanical behavior.

关键词： sandy cobble soil particle flow code orthogonal experiment regression analysis multi-objective optimization calibration

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基于对数曲线和塌落拱组合的砂卵石隧道开挖面稳定分析

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铁道标准设计 2024年第10期68卷 169-175,183页

作者：王海峰崔小普李鹏飞魏英杰吕治鹏南通铁建建设构件有限公司江苏南通226000 北京工业大学城市与工程安全减灾教育部重点实验室北京100124 中铁十四局集团有限公司济南250014

合理的支护力对于砂卵石土隧道开挖面的稳定性至关重要。借助已有对数螺旋曲线破坏模式,将塌落拱模型与极限分析法结合,建立砂卵石隧道开挖面破坏模型,并提出适用于砂卵石隧道的开挖面极限支护力计算方法。然后,将本文理论解析与数值模... 详细信息

合理的支护力对于砂卵石土隧道开挖面的稳定性至关重要。借助已有对数螺旋曲线破坏模式,将塌落拱模型与极限分析法结合,建立砂卵石隧道开挖面破坏模型,并提出适用于砂卵石隧道的开挖面极限支护力计算方法。然后,将本文理论解析与数值模拟、已有理论进行对比,获得不同内摩擦角和黏聚力下的破坏区域。最后,利用理论解析与数值模拟方法对北京某盾构隧道进行开挖面稳定性分析。结果显示,本文解析解与已有研究获得的极限支护力吻合较好,计算便捷,精度较高。极限支护力随着内摩擦角的增大呈非线性减小,且在摩擦角较小时,极限支护力对内摩擦角变化更为敏感。极限支护力随着黏聚力的增大呈近似线性减小。当埋深比较小时,其对极限支护力有着较为明显的影响。当C/D>1.0时,隧道埋深的增加对极限支护力的大小没有明显影响,摩擦角对破坏区域有非常明显的影响。随着内摩擦角的增大,破坏区域显著减小。黏聚力对破坏区域的影响非常小,即不同黏聚力下耗能面的大小几乎不变。针对北京某盾构隧道计算可以发现,基于极限分析法提出的破坏模式优化塌陷范围及形状后,使得破坏模式更加合理,同时破坏范围更大,取得了很好的工程应用效果。

关键词：支护力砂卵石隧道开挖面稳定性对数螺旋线塌落拱极限分析

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A review on numerical studies of airflow dynamics and particle deposition in human respiratory system Author links open overlay panel

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Particuology 2024年第8期91卷 351-377页

作者： Hao Jing Xinguang cui School of Aerospace Engineering Huazhong University of Science and TechnologyWuhan430074China

Accurate assessment and prediction of airflow dynamics and particle deposition in the human respiratory tract are essential for human health,involving inhaled drugs for treating various diseases and toxic particles that can cause *** intricate process involves complex multiphase flow with distinct respiratory *** fluid dynamics(CFD)acts as a bridge,overcoming the limitations of in vivo and in vitro experiments and providing a means to fully comprehend and reveal the fundamental mechanisms of respiratory flow and particle behavior on a microscopic *** paper provides a comprehensive overview and concise summary of recent advancements in the numerical simulation of airflow and particle deposition in the human respiratory ***,it summarizes the transition of respiratory tract models from segmented models to emerging physiological characteristic models and whole-lung airway models,and the latest developments on the effects of key factors such as geometric variations,respiratory patterns,and particle physical/chemical properties on respiratory flow and particle deposition.A notable focus of this review is on emerging physiological characteristics models and their associated complex airflow and particle dynamics inside *** paper concludes with recommendations for future research to further advance the development of this field.

关键词： Airflow dynamics Particle deposition Human respiratory system Numerical modeling

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Multi-Sensor Fusion Adaptive Estimation for Nonlinear Under-observed System with Multiplicative Noise

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Chinese Journal of Electronics 2024年第1期33卷 282-292页

作者： Yongpeng cui Xiaojun SUN School of Electronic Engineering Heilongjiang University Key Laboratory of Information Fusion Estimation and Detection

The adaptive fusion estimation problem was studied for the multi-sensor nonlinear under-observed systems with multiplicative noise. A one-step predictor with state update equations was designed for the virtual state with virtual noise first of all. An extended incremental Kalman filter(EIKF) was then proposed for the nonlinear under-observed systems. Furthermore, an adaptive filtering method was given for optimization. The fusion adaptive incremental Kalman filter weighted by scalar was finally proposed. The comparison analysis was made to verify the optimization of the state estimation using adaptive filtering method in the filtering process.

关键词： Adaptive systems Information filters Matrices Adaptive estimation Kalman filters State estimation Nonlinear systems

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Number of Solitons Emerged in the Initial Profile of Shallow Water Using Convolutional Neural Networks

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Journal of Systems Science & Complexity 2024年第2期37卷 463-479页

作者： WANG Zhen cui Shikun School of Mathematical Sciences Dalian University of TechnologyDalian 116024China School of Mathematical Sciences Beihang UniversityBeijing 100191China

The soliton resolution conjecture proposes that the initial value problem can evolve into a dispersion part and a soliton ***,the problem of determining the number of solitons that form in a given initial profile remains unsolved,except for a few specific *** this paper,the authors use the deep learning method to predict the number of solitons in a given initial value of the Korteweg-de Vries(KdV)*** leveraging the analytical relationship between Asech^(2)(x)initial values and the number of solitons,the authors train a Convolutional Neural Network(CNN)that can accurately identify the soliton count from spatio-temporal *** trained neural network is capable of predicting the number of solitons with other given initial values without any additional *** extensive calculations,the authors demonstrate the effectiveness and high performance of the proposed method.

关键词： Convolutional neural network deep learning method KdV equation soliton

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“Buckets effect”in the kinetics of electrocatalytic reactions

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Journal of Energy Chemistry 2024年第2期89卷 388-396,I0010页

作者： Haowen cui Yan-Xia Chen Hefei National Laboratory for Physical Sciences at Microscale Department of Chemical PhysicsUniversity of Science and Technology of ChinaHefei 230026AnhuiChina

In this study,we systematically investigated the effect of proton concentration on the kinetics of the oxygen reduction reaction(ORR)on Pt(111)in acidic *** results demonstrate a rectangular hyperbolic relationship,i.e.,the ORR current excluding the effect of other variables increases with proton concentration and then tends to a constant *** consider that this is caused by the limitation of ORR kinetics by the trace oxygen concentration in the solution,which determines the upper limit of ORR kinetics.A model of effective concentration is further proposed for rectangular hyperbolic relationships:when the reactant concentration is high enough to reach a critical saturation concentration,the effective reactant concentration will become a constant *** could be due to the limited concentration of a certain reactant for reactions involving more than one reactant or the limited number of active sites available on the *** study provides new insights into the kinetics of electrocatalytic reactions,and it is important for the proper evaluation of catalyst activity and the study of structureperformance relationships.

关键词： Oxygen reduction reaction Kinetics Zero order Rectangular hyperbolic relationship pH effect

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Nano-effect enhanced cooperative luminescence of Yb^(3+) clusters in bulk materials

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Journal of Rare Earths 2024年第3期42卷 473-478,I0002页

作者： Daguang Li Jiahao cui Yanhui Dong Hao cui Dan Zhao Weiping Qin State Key Laboratory on Integrated Optoelectronics College of Electronic Science and EngineeringJilin UniversityChangchun130012China

In order to improve the multi-ion cooperative transition, we proposed and exploited a novel nanoscale effect, namely the nanoshell effect in bulk materials. Based on the effect, an optimal material structure was designed by coating the surfaces of Ca F_(2):Yb^(3+)micron size particles with ZrO_(2). An about 2 times higher intensity of cooperative luminescence is observed upon laser excitation at 980 nm. Dynamical analysis exhibits that the novel effect plays a key role in improving the performance of cooperative transitions. Our results also suggest that the nanoshell effect in bulk materials is likely to be significant in some special cases, which have not been reported yet in the literature.

关键词： Yb^(3+)cluster ZrO_(2) Nanoshell Enhancement Cooperative luminescence Rare earths

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Influence of ammonium sulfate on the corrosion behavior of AZ31 magnesium alloy in chloride environment

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Journal of Magnesium and Alloys 2024年第3期12卷 1082-1101页

作者： Feng Ge Zhongyu cui Yue Liu Li Lei Xin Wang Hongzhi cui School of Materials Science and Engineering Ocean University of ChinaQingdao 266100China Beijing National Innovation Institute of Lightweight Ltd.Beijing 101499China

Electrochemical corrosion of AZ31 magnesium alloy in the NH_(4)^(+)-SO_(4)2−-Cl−environment is *** of NH_(4)^(+)overshadows that of Cl−as the(NH_(4))_(2)SO_(4) concentration is 0.005 M or higher,yielding an evolution from localized corrosion to uniform *** effect of NH_(4)^(+)can be attributed to that(i)NH_(4)^(+)dissolves the inner MgO and hinders the precipitation of Mg(OH)_(2) and(ii)the buffering ability of NH_(4)^(+)provides H+,enhances the hydrogen evolution,and expedites the corrosion *** latter is demonstrated as the dominant factor with the results in unbuffered and buffered *** severe corrosion and hydrogen process in NH_(4)^(+)-containing solution results in a high Hads coverage and yields an inductive loop within the low ***,SO_(4)^(2−)is helpful in generating cracked but partially protective corrosion products,while Cl−could broaden the corrosion area beneath the corrosion product.

关键词： Magnesium alloy Ammonium corrosion Electrochemical kinetic parameter Anodic dissolution.

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