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Development and application of novel high‐efficiency composite ultrafine cement grouts for roadway in fractured surrounding rocks

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Deep Underground Science and engineering 2024年第1期3卷 53-69页

作者： Maolin Tian Shaojie Chen Lijun Han Hongtian Xiao shandong key laboratory of civil engineering disaster prevention and mitigation Shandong University of Science and TechnologyQingdaoChina College of civil engineering and Architecture Shandong University of Science and TechnologyQingdaoChina College of Energy and Mining engineering Shandong University of Science and TechnologyQingdaoChina State key laboratory for Geomechanics and Deep Underground engineering China University of Mining and TechnologyXuzhouChina

The fractured surrounding rocks of roadways pose major challenges to safe mining.Grouting has often been used to reinforce the surrounding rocks to mitigate the safety risks associated with fractured rocks.The aim of this study is to develop highly efficient composite ultrafine cement(CUC)grouts to reinforce the roadway in fractured surrounding rocks.The materials used are ultrafine cement(UC),ultrafine fly ash(UF),ultrafine slag(US),and additives(superplasticizer[SUP],aluminate ultrafine expansion agent[AUA],gypsum,and retarder).The fluidity,bleeding,shrinkage,setting time,chemical composition,microstructure,degree of hydration,and mechanical property of grouting materials were evaluated in this study.Also,a suitable and effective CUC grout mixture was used to reinforce the roadway in the fractured surrounding rock.The results have shown that the addition of UF and US reduces the plastic viscosity of CUC,and the best fluidity can be obtained by adding 40%UF and 10%US.Since UC and UF particles are small,the pozzolanic effect of UF promotes the hydration reaction,which is conductive to the stability of CUC grouts.In addition,fine particles of UC,UF,and US can effectively fill the pores,while the volumetric expansion of AUA and gypsum decreases the pores and thus affects the microstructure of the solidified grout.The compressive test results have shown that the addition of specific amounts of UF and US can ameliorate the mechanical properties of CUC grouts.Finally,the CUC22‐8 grout was used to reinforce the No.20322 belt roadway.The results of numerical simulation and field monitoring have indicated that grouting can efficaciously reinforce the surrounding rock of the roadway.In this research,high‐performance CUC grouts were developed for surrounding rock reinforcement of underground engineering by utilizing UC and some additives.

关键词： broken surrounding rock composite ultrafine cement(CUC)grouts grouting material grouting performance grouting reinforcement

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Layered metastructure containing freely-designed local resonators for wave attenuation

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Defence Technology（防务技术） 2024年第2期32卷 23-31页

作者： Yu Li Huguang He Jiang Feng Hailong Chen Fengnian Jin Hualin Fan State key laboratory for disaster prevention&mitigation of Explosion&Impact Army Engineering University of PLANanjing 210007China Rocket Force University of engineering Xi'an 710025China Henan International Joint laboratory of Dynamics of Impact and disaster of engineering Structures Department of Civil EngineeringNanyang Institute of TechnologyNanyang 473004China Guangxi key laboratory of disaster prevention and engineering Safety and Key Laboratory of Disaster Prevention and Structural Safety of Ministry of EducationCollege of Civil Engineering and ArchitectureGuangxi UniversityNanning 530004China Research Center of Lightweight Structures and Intelligent Manufacturing State Key Laboratory of Mechanics and Control of Mechanical StructuresNanjing University of Aeronautics and AstronauticsNanjing 210016China

Combining periodic layered structure with three-dimensional cylindrical local resonators,a hybrid metastructure with improved wave isolation ability was designed and investigated through theoretical and numerical approaches.The metastructure is composed of periodic rubber layers and concrete layers embedded with three-dimensional resonators,which can be freely designed with multi local resonant frequencies to attenuate vibrations at required frequencies and widen the attenuation bandgap.The metastructure can also effectively attenuate seismic responses.Compared with layered rubber-based structures,the metastructure has more excellent wave attenuation effects with greater attenuation and wider bandgap.

关键词： Layered metastructure Local resonator Wave attenuation

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FRAGILITY ANALYSIS OF STRUCTURES WITH TUNED VISCOUS MASS DAMPERS UNDER NEAR-FAULT PULSE-TYPE GROUND MOTIONS

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Gongcheng Lixue/engineering Mechanics 2024年第6期41卷 212-223页

作者： Zhang, Li-Li Han, Jian-Ping Li, Da-Wei Ma, Lian-Sheng key laboratory of disaster prevention and mitigation in civil engineering of Gansu Province Lanzhou University of Technology Lanzhou 730050 China Western engineering Research Center of disaster mitigation in civil engineering of Ministry of Education Lanzhou University of Technology Lanzhou 730050 China School of Science Lanzhou University of Technology Lanzhou 730050 China

A series of incremental dynamic analysis (IDA) were conducted on 6-storey 3-bay steel frames subjected to selected near-fault pulse-type ground motions. The frames are installed with tuned viscous mass dampers (TVMDs), viscous dampers (VDs) or no dampers, respectively. The seismic fragility curves corresponding to different damage states were obtained based on IDA results. The comparison of the seismic fragility of structures between TVMDs and VDs shows that the reliabilities of the main structure against different damage states are improved significantly with the addition of inerter element. Given the same damping ratio, the structure with TVMDs exhibits excellent improvement in seismic resistant capacity and low damage failure probability of the main structure against different damage states. With the increase of mass ratio, the improvement in structural performance due to TVMD does not decrease with the increase of nonlinearity. And the seismic mitigation effect of the structure is stable during the whole process including elasticity, elastic-plasticity and collapse. Furthermore, three sets of near-fault ground motion records with different pulse periods were selected for time history analysis, and the seismic mitigation effect of TVMD under near-fault pulse-type ground motions was discussed. The results show that under the near-fault pulse-type ground motions, TVMD does not always achieve the damping enhancement of the damping element, and the performance of the damper is related to the characteristics of ground motions. Compared with the enhanced structure with VDs and the original benchmark model, TVMD system reduces the input energy of the main structure when T1/Tp≥2. However, it has lower capacity of energy dissipation and the effect of damping enhancement could not be realized. When T1/Tp © 2024 Tsinghua University. All rights reserved.

关键词： Energy dissipation

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PARAMETER OPTIMIZATION AND VIBRATION REDUCTION ANALYSIS OF DOUBLE ELECTROMAGNETIC SHUNT TUNED MASS DAMPER

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Gongcheng Lixue/engineering Mechanics 2024年第5期41卷 155-166页

作者： Sun, Hong-Xin Huang, Chao-Yang Luo, Yi-Fan Wang, Xiu-Yong Wen, Qing School of civil engineering Hu’nan University of Science and Technology Hu’nan Provincial Key Laboratory of Intelligent Disaster Prevention-Mitigation and Ecological Restoration in Civil Engineering Hu’nan Xiangtan 411201 China

A novel electromagnetic shunt tuned mass damper (EMS-TMD) is proposed for structural vibration control. A new feature of the damper is the electromagnetic damping element that replaces the viscous damping of the traditional double tuned mass dampers. To further improve the damping performance and robustness of the damper, a double electromagnetic shunt tuned mass damper (DEMS-TMD) is designed. According to the Alembert’s theorem, the dynamic model of the coupled system DEMS-TMD and a single degree of freedom structure under seismic excitation is established. Based on the Monte Carlo pattern search method with the target of minimizing the value of the maximum dynamic amplification coefficient of the main structure displacement, the optimal parameters of DEMS-TMD, the structure frequency ratio, the electrical frequency ratio, the electromagnetic damping ratio and the electromechanical coupling coefficient are obtained, which provides the theoretical guidance for damping parameter design. The frequency and time domain simulations of the DEMS-TMD are conducted to analyze the performance of the vibration suppression of the DEMS-TMD. The results show that the reduction of the peak and RMS values of main structure displacement of the DEMS-TMD is superior to traditional parallel double tuned mass dampers (DTMD) in the frequency domain simulations. The reduction of the peak and RMS values of displacement and acceleration of the DEMS-TMD is superior to traditional DTMD in the time domain simulations, which shows the better damping effect of the DEMS-TMD on structures. © 2024 Tsinghua University. All rights reserved.

关键词： Acceleration

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Three-dimensional limit variation analysis on the ultimate pullout capacity of the anchor cables based on the Hoek-Brown failure criterion

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Journal of Mountain Science 2024年第3期21卷 1036-1047页

作者： ZUO Shi ZHAO Lianheng HU Shihong College of civil engineering Changsha UniversityChangsha 410022China Hunan Provincial key laboratory for disaster prevention and mitigation of Rail Transit engineering Structure Key Laboratory of Heavy-Haul Railway Engineering StructureMinistry of EducationCentral South UniversityChangsha 410075China College of civil engineering Central South UniversityChangsha 410075China

Only simplified two-dimensional model and a single failure mode are adopted to calculate the ultimate pullout capacity(UPC)of anchor cables in most previous research.This study focuses on a more comprehensive combination failure mode that consists of bond failure of an anchorage body and failure of an anchored rock mass.The three-dimensional ultimate pullout capacity of the anchor cables is calculated based on the Hoek-Brown failure criterion and variation analysis method.The numerical solution for the curvilinear function in fracture plane is obtained based on the finite difference theory,which more accurately reflects the failure state of the anchor cable,as opposed to that being assumed in advance.The results reveal that relying solely on a single failure mode for UPC calculations has limitations,as changes in parameter values not only directly impact the UPC value but also can alter the failure model and thus the calculation method.

关键词： Anchor cable Ultimate pullout capacity(UPC) Failure model Variation analysis Hoek-Brown failure criterion

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Stability analysis of intermittently jointed rock slopes based on the stepped failure mode

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Journal of Mountain Science 2024年第3期21卷 1019-1035页

作者： LI Dejian FU Junwen LI Hekai CHENG Xiao ZHAO Lianheng ZHANG Yingbin PENG Xinyan School of civil engineering Southwest Jiaotong UniversityChengdu 610031China Institute for disaster Management and Reconstruction College of Architecture&EnvironmentSichuan UniversityChengdu 610065China School of civil engineering Key Laboratory of Heavy-Haul Railway Engineering StructureMinistry of EducationHunan Provincial Key Laboratory for Disaster Prevention and Mitigation of Rail Transit Engineering StructureCentral South UniversityChangsha 410075China

In practical engineering,due to the noncontinuity characteristics of joints in rock slopes,in addition to plane failure,stepped sliding failure may occur for intermittently jointed rock slopes.Especially for intermittently bedding jointed rock slopes,the correlation and difference in strength parameters between joints and rock bridges,along with the various failure modes and intermittency of rock bridges,contribute to the complexity of stepped failure modes and the unpredictability of failure regions.Based on the upper-bound limit analysis method and multi-sliders step-path failure mode,considering the shear and tensile failure of rock bridges and the weakened relationship between the strength parameters of rock bridges and jointed surfaces,by introducing the modified M-C failure criterion and the formula for calculating the energy consumption of tensile failure of rock bridges,two failure mechanisms are constructed to obtain the safety factor(F_(s))of intermittently jointed rock slopes.The sequential quadratic programming method is used to obtain the optimal upper-bound solution for F_(s).The influence of multiple key parameters(slope height H,horizontal distance L,Slope angleβ,shear strength parameters of the rock bridgeφr and cr,Dimensionless parameter u,weakening coefficients of the internal friction angle and cohesion between the rock bridges and joint surfaces Kφand Kc)on the stability analysis of intermittently jointed rock slopes under the shear failure mode of rock bridges as well as under the tensile failure mode is also explored.The reliability of the failure mechanisms is verified by comparative analysis with theoretical results,numerical results,and landslide cases,and the variation rules of F_(s)with each key parameter are obtained.The results show that F_(s) varies linearly withφr and cr of the rock bridge and with K_(φ)and K_(c),whereas F_(s)changes nonlinearly with H and L.In particular,with the increase in Kφand Kc,Fs increases by approximately 52.78%and 171.02%on average,respectively.For rock b

关键词： Jointed rock slopes Stepped sliding failure Weakening characteristics Modified M‒C failure criterion

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Study on a conical bearing for acceleration-sensitive equipment

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Earthquake engineering and engineering Vibration 2024年第1期23卷 103-128页

作者： Pang Hui Xu Wen Dai Junwu Jiang Tao key laboratory of Earthquake engineering and engineering Vibration Institute of Engineering MechanicsChina Earthquake AdministrationHarbin 150080China key laboratory of Earthquake disaster mitigation Ministry of Emergency ManagementHarbin 150080China School of civil engineering and Transportation Beihua UniversityJilin 132013China

Seismic isolation effectively reduces seismic demands on building structures by isolating the superstructure from ground vibrations during earthquakes.However,isolation strategies give less attention to acceleration-sensitive systems or equipment.Meanwhile,as the isolation layer’s displacement grows,the stiffness and frequency of traditional rolling and sliding isolation bearings increases,potentially causing self-centering and resonance concerns.As a result,a new conical pendulum bearing has been selected for acceleration-sensitive equipment to increase self-centering capacity,and additional viscous dampers are incorporated to enhance system damping.Moreover,the theoretical formula for conical pendulum bearings is supplied to analyze the device’s dynamic parameters,and shake table experiments are used to determine the proposed device’s isolation efficiency under various conditions.According to the test results,the newly proposed devices have remarkable isolation performance in terms of minimizing both acceleration and displacement responses.Finally,a numerical model of the isolation system is provided for further research,and the accuracy is demonstrated by the aforementioned experiments.

关键词： seismic isolation acceleration-sensitive equipment the conical pendulum bearing shake table tests isolation performance,numerical model

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A unified stochastic damage model for concrete based on multi-scale energy dissipation analysis

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Science China(Technological Sciences) 2024年第3期67卷 863-877页

作者： GUO ChengGong LI Jie College of civil engineering Tongji UniversityShanghai 200092China State key laboratory of disaster Reduction in civil engineering Shanghai 200092China

This work proposes a unified damage model for concrete within the framework of stochastic damage mechanics. Based on the micro-meso stochastic fracture model(MMSF), the nonlinear energy dissipation process of the microspring from nanoscale to microscale is investigated. In nanoscale, the rate process theory is adopted to describe the crack growth rate;therefore, the corresponding energy dissipation caused by a representative crack propagation can be obtained. The scale gap from nanoscale to microscale is bridged by a crack hierarchy model. Thus, the total energy dissipated by all cracks from the nanoscale to the microscale is gained. It is found that the fracture strain of the microspring can be derived from the above multi-scale energy dissipation analysis. When energy dissipation is regarded as some microdamage to the microspring, the constitutive law of the microspring is no longer linearly elastic, as previously assumed. By changing the expression of the damage evolution law from fracture strain to energy dissipation threshold, the new damage evolution model is derived. The proposed model can not only replicate the original static model but also extend to cases of rate dependence. By deriving the fracture strain under different strain rates, the rate sensitivity of concrete materials can be reflected. The model parameters can be conveniently obtained by identifying them with experimental data. Finally, several numerical examples are presented to verify the proposed model.

关键词： concrete damage model stochastic damage rate dependent energy dissipation

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Accurate Analysis of Multi-Mode Interferometric Optical Fiber Sensor

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Photonic Sensors 2024年第1期14卷 48-58页

作者： Lijun LI Congying JIA Qian MA Tianzong XU College of Electronic and Information engineering Shandong University of Science and TechnologyQingdao 266590.China State key laboratory of Mining disaster prevention and Control Co-Founded by shandong Province and the Ministry of Science and Technology Qingdao 266590China

In view of the problem that the sensing characteristics of the multi-mode interferometric fiber sensors cannot be accurately analyzed,an analysis method based on the fast Fourier transform(FFT)and inverse fast Fourier transform(IFFT)is proposed and demonstrated theoretically and experimentally.The suitabilities of the rectangular window function with the narrow main lobe(high spectrum resolution)and low side lobe(high main mode energy leakage)and the Hanning window function with the wide main lobe(low spectrum resolution)and high side lobe(high energy concentration)in this kind of sensor analysis are discussed,respectively.This method can not only realize the sensing performance analysis of the various modes,but also overcome the inconsistency of the different interference wavelength(dip)sensing characteristics in the conventional analysis methods.At the same time,this method is also beneficial to solve the repetitive problem of such sensors.

关键词： Window function FFT optical fiber interferometric sensor analysis method

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Effect of Wave Nonlinearity on the Instantaneous Seabed Liquefaction

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China Ocean engineering 2024年第1期38卷 93-103页

作者： WANG Zhao-jun SUI Ti-ti ZHANG Chi PAN Jun-ning key laboratory of Port Waterway and Sedimentation Engineering of the Ministry of TransportNanjing Hydraulic Research InstituteNanjing 210024China key laboratory of Coastal disaster and Protection(Hohai University) Ministry of EducationNanjing 210098China The National key laboratory of Water disaster prevention Nanjing 210098China

The nonlinear variation of wave is commonly seen in nearshore area,and the resulting seabed response and liquefaction are of high concern to coastal engineers.In this study,an analytical formula considering the nonlinear wave skewness and asymmetry is adopted to provide wave pressure on the seabed surface.The liquefaction depth attenuation coefficient and width growth coefficient are defined to quantitatively characterize the nonlinear effect of wave on seabed liquefaction.Based on the 2D full dynamic model of wave-induced seabed response,a detailed parametric study is carried out in order to evaluate the influence of the nonlinear variation of wave loadings on seabed liquefaction.Further,new empirical prediction formulas are proposed to fast predict the maximum liquefaction under nonlinear wave.Results indicate that(1)Due to the influence of wave nonlinearity,the vertical transmission of negative pore water pressure in the seabed is hindered,and therefore,the amplitude decreases significantly.(2)In general,with the increase of wave nonlinearity,the liquefaction depth of seabed decreases gradually.Especially under asymmetric and skewed wave loading,the attenuation of maximum seabed liquefaction depth is the most significant among all the nonlinear wave conditions.However,highly skewed wave can cause the liquefaction depth of seabed greater than that under linear wave.(3)The asymmetry of wave pressure leads to the increase of liquefaction width,whereas the influence of skewedness is not significant.(4)Compared with the nonlinear waveform,seabed liquefaction is more sensitive to the variation of nonlinear degree of wave loading.

关键词： nonlinear wave seabed response seabed liquefaction numerical simulation liquefaction prediction

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