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Seismic and vibration control of segmented isolation layer in underground structure-diaphragm wall system

Underground Space 2024年第6期19卷 72-86页

作者： Zhidong Gao Mingbo Li Mi Zhao Xiuli Du Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education Beijing University of TechnologyBeijing 100124China Department of Hydraulic Engineering Tsinghua UniversityBeijing 100084China

In this paper,a seismic and vibration reduction measure of subway station is developed by setting a segmented isolation layer between the sidewall of structure and the diaphragm *** segmented isolation layer consists of a rigid layer and a flexible *** rigid layer is installed at the joint section between the structural sidewall and slab,and the flexible layer is installed at the remaining sections.A diaphragm wall-segmented isolation layer-subway station structure system is *** and vibration control performance of the diaphragm wall-segmented isolation layer-subway station structure system is evaluated by the detailed numerical ***,a three-dimensional nonlinear time-history analysis is carried out to study the seismic response of the station structure by considering the effect of different earthquake motions and stiffness of segmented isolation ***,the vibration response of site under training loading is also studied by considering the influence of different train velocities and stiffness of the segmented isolation *** results demonstrate that the diaphragm wall-segmented isolation layer-subway station structure system can not only effectively reduce the lateral deformation of station structure,but also reduce the tensile damage of the roof *** the other hand,the developed reduction measure can also significantly reduce the vertical peak displacements of site under training loading.

关键词： Subway station Diaphragm wall Segmented isolation layer Seismic response Train vibration

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Experimental study on cyclic deformation properties of saturated Fujian sand at different loading frequencies

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Underground Space 2023年第6期13卷 150-165页

作者： Chong Yue Ke Liang Chengshun Xu Xiuli Du Key Laboratory of Urban Security and Disaster Engineering of the Ministry of Education Beijing University of TechnologyBeijing 100124China

In this study,a series of undrained cyclic torsional shear tests were conducted to investigate the effect of cyclic loading frequency f on the pre-liquefaction(shearing contractive(SC)period and initial shearing dilative(ISD)period)and post-liquefaction(late shearing dilative(LSD)period)deformation properties of saturated Fujian *** secant shear modulus G and damping ratioλin the entire cyclic loading process,and the unloading tangent shear modulus G_(L1)and flow deformation tangent shear modulus GL2 in the ISD and LSD periods were adopted to quantitatively characterize the evolution of hysteresis loop with an increase in shear strain amplitude *** test results show that the effect of f on G of saturated Fujian sand in the SC period is not ***,all the G-γ_(a),G_(L1)-γ_(a),and GL2-ca curves in the ISD and LSD periods showed a downward trend with an increase in *** study also proposes a modified method for calculatingλto compensate for the analytical error caused by the non-closure of hysteresis *** with the classical curves that mainly applied in geotechnical engineering,theλfirst increases and then decreases with the increase ofγ***,theλevaluated by the modified method is approximately 10%–15%more than theλevaluated by the traditional method when theλreaches its peak value.

关键词： Sand liquefaction Cyclic loading frequency Hysteresis loop shape Shear modulus Damping ratio

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Influence of permeability anisotropy of seepage flow on the tunnel face stability

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Underground Space 2023年第1期8卷 1-14页

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

This paper focuses on the influence of permeability anisotropy of seepage flow on the face stability for a shied *** analytical model has been proposed to present the hydraulic head distribution around the tunnel face in the anisotropic ground,considering the difference of permeability coefficient in the horizontal direction and the vertical *** rationality of the proposed model is ver-ified by a series of numerical ***,an analytical model of face stability for a tunnel under the anisotropic seepage has been established based on the limit analysis upper bound *** of the analytical solutions and the numerical simulations are conducted,and the limit support pressure of the two methods is *** effect of permeability anisotropy and water pressure on the stability of the tunnel face is analyzed through the three-dimensional analytical *** of permeability has a significant impact on the stability of the tunnel face,and its impact gradually *** can also be found that the water pressure coefficient of the tunnel face has a significant effect on the limit support pressure and the failure area when the ratio of the horizontal permeability to the vertical permeability is large.

关键词： Seepage flow Hydraulic head distribution Permeability anisotropy Shield tunnel Water pressure

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Predictions of ground surface settlement for shield tunnels in sandy cobble stratum based on stochastic medium theory and empirical formulas

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Underground Space 2023年第4期11卷 189-203页

作者： Fan Wang Xiuli Du Pengfei Li Key Laboratory of Urban Security and Disaster Engineering Ministry of EducationBeijing University of TechnologyBeijing 100124China

This paper focuses on the prediction of ground surface settlement induced by shield tunnelling in sandy cobble *** on the stochastic medium theory,an analytical solution to predict the surface settlement is developed considering the difference between soil and tunnel volume ***,the effects of tunnel geometries,influence angle and volume loss on the characteristics of surface settlement are *** back analysis,a total of 103 groups of field monitoring data of surface settlement induced by shield tunnelling in sandy cobble stratum are examined to investigate the statistical characteristics of the maximum settlement,settlement trough width and volume *** empirical prediction is presented based on the results of back ***,the analytical solution and empirical expression are validated by the comparisons with the results of model tests and field *** show that the soil at ground surface has an overall dilative response for most of the shield tunnelling in sandy cobble *** addition,the developed analytical solution is applicable and reasonable for surface settlement ***,the proposed empirical formula also shows good per-formance in some cases,providing an approach or a reference for engineering designers to preliminarily evaluate the surface settlement.

关键词： Shield tunnelling Sandy cobble stratum Ground surface settlement Stochastic medium theory Empirical formulas

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Critical state uniqueness of dense granular materials using discrete element method in conjunction with flexible membrane boundary

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Particuology 2024年第12期95卷 124-144页

作者： Chenglong Jiang Yajing Liu Lingling Zeng Chengshun Xu Peng Cao College of Civil Engineering Zhejiang University of TechnologyZhejiang310023China The Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education Beijing University of TechnologyBeijing100124China

An explanation of the meso-mechanism of sand granular materials for the uniqueness of critical state is presented by means of the discrete element method(DEM)under flexible boundary loading conditions.A series triaxial drainage shear test(DEM simulations),in conjunction with the flexible boundary technique,of were performed for sand samples subjected to various physical states and with different particle size *** carefully investigating the critical status of the results of the numerical calculation,the macroscopic failure modes and shear band evolution of sand,as well as the velocity vector field due to different initial states,were explored and ***,the evaluation rules and discrepancies between overall void ratios of the specimen and local void ratios within the shear band under the critical state were recorded and *** results proved that a sample with a small void tends to form a shear band,and the rotation of the particles in the non-shear zone is ***,sandy soil with large initial void ratios exhibited limited development of significant shear bands,and the change in void ratios within the shear region and the non-shear area are not ***,the particle-size distribution exerts minimal influence on the evolution rule which the void ratio converges within the shear band and diverges outside the shear region for both multi-stage and single-stage *** void ratio within the shear band and deviator stress ratio tend to exhibit consistently for the same specimen with different initial physical states,thereby distinguishing the critical *** is a significantly higher change in void ratio within the shear band compared to outside of it,yet it remains stable within a relatively similar ***,the invariant of the fabric tensor used to describe the critical state characteristics also demonstrates a high degree of consistency within the shear *** findings stron

关键词： Critical state Flexible membrane boundary Evolution of the void ratio Shear band Fabric tensor

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An Enhanced Clustering-Based (k, t)-Anonymity Algorithm for Graphs

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Chinese Journal of Electronics 2025年第1期34卷 365-372页

作者： Yuanyuan Wang Xing Zhang Zhiguang Chu Wei Shi Xiang Li School of Electronics and Information Engineering Liaoning University of Technology Key Laboratory of Security for Network and Data in Industrial Internet of Liaoning Province Faculty of Information Technology Beijing University of Technology

As people become increasingly reliant on the Internet, securely storing and publishing private data has become an important issue. In real life, the release of graph data can lead to privacy breaches, which is a highly challenging problem. Although current research has addressed the issue of identity disclosure, there are still two challenges: First, the privacy protection for large-scale datasets is not yet comprehensive; Second, it is difficult to simultaneously protect the privacy of nodes, edges, and attributes in social networks. To address these issues, this paper proposes a(k,t)-graph anonymity algorithm based on enhanced clustering. The algorithm uses k-means++ clustering for k-anonymity and t-closeness to improve k-anonymity. We evaluate the privacy and efficiency of this method on two datasets and achieved good results. This research is of great significance for addressing the problem of privacy breaches that may arise from the publication of graph data.

关键词： Data privacy Uncertainty Social networking (online) Publishing Heuristic algorithms Scalability Clustering algorithms Privacy breach Internet Protection

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Effect of burial depth of a new tunnel on the seismic response of an existing tunnel

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Earthquake engineering and engineering Vibration 2024年第4期23卷 863-882页

作者： Ma Runbo Cao Qikun Lu Shasha Zhao Dongxu Zhang Yanan Xu Hong College of Civil Engineering Liaoning Technical UniversityFuxin 123000China Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education Beijing University of TechnologyBeijing 100124China

Burial depth is a crucial factor affecting the forces and deformation of tunnels during *** key issue is a lack of understanding of the effect of a change in the buried depth of a single-side tunnel on the seismic response of a double-tunnel *** this study,shaking table tests were designed and performed based on a tunnel under construction in Dalian,*** models were established using the equivalent linear method combined with ABAQUS finite element software to analyze the seismic response of the interacting *** results showed that the amplification coefficient of the soil acceleration did not change evidently with the burial depth of the new tunnel but decreased as the seismic amplitude *** addition,the existing tunnel acceleration,earth pressure,and internal force were hardly affected by the change in the burial depth;for the new tunnel,the acceleration and internal force decreased as the burial depth increased,while the earth pressure *** shows that the earth pressure distribution in a double-tunnel system is relatively complex and mainly concentrated on the arch spandrel and arch springing of the relative ***,when the horizontal clearance between the center of the two tunnels was more than twice the sum of the radius of the outer edges of the two tunnels,the change in the burial depth of the new tunnel had little effect on the existing one,and the tunnel structure was deemed *** results provide a preliminary understanding and reference for the seismic performance of a double-tunnel system.

关键词： burial depth new tunnel existing tunnel seismic response shaking table tests numerical simulations

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SMP-NoC: A Flexible and Efficient Shared Memory Protection Unit on Network-on-Chip 24th

SMP-NoC: A Flexible and Efficient Shared Memory Protection ...

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24th International Conference on Algorithms and Architectures for Parallel Processing, ICA3PP 2024

作者： Wu, Teng He, Ying Wei, Shengjun Hu, Changzhen School of Cyberspace Science and Technology Beijing Institute of Technology Beijing China Beijing Key Laboratory of Software Security Engineering Technology Beijing Institute of Technology Beijing China

ISBN: (纸本)9789819615445

Network-on-Chip (NoC) is crucial for modern multicore systems, offering high throughput and low latency. However, its shared memory faces threats like illegal access and DDoS attacks. To enhance security, Memory Protection Units (MPUs) with permission tables are used to control access. NoC-MPU architecture uses TLBs and permission tables for request checks and domain isolation via CIDs, but this can cause high latency. To address this, DPU and NSM are combined for dynamic permission updates, though the tables remain static. Our paper introduces a novel Flexible and Efficient Real-Time Memory Protection Unit for NoC, featuring a hardware sandbox and taint-track monitor for pre-testing access requests. It supports dynamic memory region adjustments based on four permissions (RX, RWX, RW, R) and includes an access controller to counter DoS and side channel attacks. The design significantly boosts NoC security with minimal overheads: just 6.2% in throughput, 7.8% in area, and 4.8% in power, outperforming current solutions. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2025.

关键词： hardware-level sandbox Network-on-Chip(NoC) shared Memory taint-track monitor

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Numerical manifold method for steady-state nonlinear heat conduction using Kirchhoff transformation

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Science China(Technological Sciences) 2024年第4期67卷 992-1006页

作者： ZHANG LiMei KONG Heng ZHENG Hong Key Laboratory of Urban Security and Disaster Engineering Ministry of EducationBeijing University of TechnologyBeijing 100124China Beijing Municipal Construction Co. Ltd.Beijing 100048China

The numerical manifold method(NMM)introduces the mathematical and physical cover to solve both continuum and discontinuum problems in a unified *** this study,the NMM for solving steady-state nonlinear heat conduction problems is presented,and heat conduction problems consider both convection and radiation boundary ***,the nonlinear governing equation of thermal conductivity,which is dependent on temperature,is transformed into the Laplace equation by introducing the Kirchhoff *** transformation reserves linearity of both the Dirichlet and the Neumann boundary conditions,but the Robin and radiation boundary conditions remain ***,the NMM is employed to solve the Laplace equation using a simple iteration procedure because the nonlinearity focuses on parts of the problem domain ***,the temperature field is retrieved through the inverse Kirchhoff *** examples are analyzed,demonstrating the advantages of the Kirchhoff transformation over the direct solution of nonlinear equations using the NewtonRaphson *** study provides a new method for calculating nonlinear heat conduction.

关键词： numerical manifold method nonlinear heat conduction temperature-dependent thermal conductivity Kirchhoff transformation convection and radiation boundary conditions

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ICCG:low-cost and efficient consistency with adaptive synchronization for metadata replication

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Frontiers of Computer Science 2025年第1期19卷 53-70页

作者： Chenhao ZHANG Liang WANG Jing SHANG Zhiwen XIAO Limin XIAO Meng HAN Bing WEI Runnan SHEN Jinquan WANG State Key Laboratory of Software Development Environment Beihang UniversityBeijing 100191China School of Computer Science and Engineering Beihang UniversityBeijing 100191China School of Cyberspace Security Hainan UniversityHaikou 570228China China Mobile Information Technology Center Beijing 100033China

The rapid growth in the storage scale of wide-area distributed file systems (DFS) calls for fast and scalable metadata management. Metadata replication is the widely used technique for improving the performance and scalability of metadata management. Because of the POSIX requirement of file systems, many existing metadata management techniques utilize a costly design for the sake of metadata consistency, leading to unacceptable performance overhead. We propose a new metadata consistency maintenance method (ICCG), which includes an incremental consistency guaranteed directory tree synchronization (ICGDT) and a causal consistency guaranteed replica index synchronization (CCGRI), to ensure system performance without sacrificing metadata consistency. ICGDT uses a flexible consistency scheme based on the state of files and directories maintained through the conflict state tree to provide an incremental consistency for metadata, which satisfies both metadata consistency and performance requirements. CCGRI ensures low latency and consistent access to data by establishing a causal consistency for replica indexes through multi-version extent trees and logical time. Experimental results demonstrate the effectiveness of our methods. Compared with the strong consistency policies widely used in modern DFSes, our methods significantly improve the system performance. For example, in file creation, ICCG can improve the performance of directory tree operations by at least 36.4 times.

关键词： metadata management metadata replication consistency directory tree replica index

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