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Creep damage co.stitutive model of rock based on the mechanisms of crack-initiated damage and extended damage

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Underground Space 2024年第5期18卷 295-313页

作者： Tianbin Li Chao Chen Feng Peng Chunchi Ma Mou Li Yixiang Wang State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu 610059China co.lege of Environment and Civil Engineering Chengdu University of TechnologyChengdu 610059China School of Urban co.struction Chengdu PolytechnicChengdu 610218China Shudao Investment group co. LtdChengdu 610094China

Since the classical element model cannot describe the nonlinear characteristics of rock during the entire co.pressive creep process,nonlinear elements and creep damage are generally introduced in the model to resolve this ***,several previous studies have reckoned that creep damage in rock only occurs in the accelerated creep stage and is only described by the Weibull ***,the creep damage mechanism of rocks is still not clearly *** this study,a reasonable representation of the damage variables of solid materials is ***,based on the Gurson damage model,the damage state functions reflecting the co.stant creep stage and accelerated creep stage of rock are ***,the one-dimensional and three-dimensional creep damage co.stitutive equations of rock are derived by modifying the Nishihara ***,the creep-aco.stic emission tests of phyllite under different co.fining pressures are co.ducted to examine the creep damage characteristics of *** the proposed co.stitutive model is verified by analyzing the results of creep tests performed on saturated ***,this study reveals the relationship between the creep characteristics of rocks and the co.responding damage evolution pattern,which bridges the gap between the traditional theory and the quantitative analysis of rock creep and its damage pattern.

关键词： Rock Creep damage co.stitutive model Damage state function Indoor tests

Hydration Behavior and Cementitious Properties of Calcium Carbonate-aluminate Minerals co.posite

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Journal of Wuhan University of Technology(Materials Science) 2024年第1期39卷 126-133页

作者：王冲周帅 ZOU Luyao LIU Jiawen ZHENG Yalin co.lege of Materials Science and Engineering Chongqing UniversityChongqing 400045China China West co.struction group co. Ltd.Chengdu 610015China

The purpose of this research is to investigate the hydration behavior and cementitious properties of the mixture of calcium carbonate and aluminate, and to explore whether it can be adopted as a new low-carbon cementitious material. The co.posite system of calcium carbonate and aluminate minerals is studied by measuring the co.ponent of hydration products, the hydration heat, setting time and co.pressive *** results prove that the co.posite system has certain cementitious properties and is feasible to prepare new low-carbon cement.

关键词： limestone hydrated calcium carboaluminate cementitious properties mechanical properties

Deformation-based longitudinal equivalent stiffness beam model for shield tunnel and its application in seismic deformation method

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Underground Space 2024年第4期17卷 280-299页

作者： Pingliang Chen Ping Geng Junbo Chen Qi Yang Key Laboratory of Transportation Tunnel Engineering Ministry of EducationSouthwest Jiaotong UniversityChengdu 610031China State Key Laboratory of Intelligent Geotechnics and Tunnelling Chengdu 610031China Technology Center of Sichuan Road&Bridge group co. LtdChengdu 610041China

In the longitudinal seismic deformation method for shield tunnels,one of the most co.monly used is the longitudinal equivalent stiffness beam model(LES)for simulating the mechanical behavior of the *** this model,axial deformation and bending deformation are independent,so the equivalent stiffness is a co.stant ***,the actual situation is that axial deformation and bending deformation occur simultaneously,which is not co.sidered in *** present,we are not clear about the effect on the calculation results when axial deformation and bending deformation occur ***,in this paper,we improve the traditional LES by taking the relative deformation as a load and co.sidering the co.rdinated deformation of axial and bending degrees of *** improved model is called DNLES,and its neutral axis equations are an explicit ***,we propose an iterative algorithm to solve the calculation model of the DNLES-based longitudinal seismic deformation *** a calculation example,we find that the internal forces based on LES are notably underestimated than those of DNLES in the co.pression bending zone,while are overestimated in the tension bending *** co.sidering the co.bined effect,the maximum bending moment reached 13.7 times that of the LES model,and the axial pressure and tension were about 1.14 and 0.96 times,*** analysis reveals the co.rdinated deformation process in the axial and bending directions of the shield tunnel,which leads to a co.sequent change in equivalent *** explains why,in the longitudinal seismic deformation method,the traditional LES may result in unreasonable calculation results.

关键词： Shield tunnel Longitudinal seismic deformation method Longitudinal equivalent stiffness beam co.bined axial and bending deformation

Vibration response and safety co.trol for blasting vibration of the existing tunnel with defects

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Underground Space 2024年第2期15卷 76-89页

作者： Junying Xia Bo Wang Xinxin Guo Zhuoxiong Xie Key Laboratory of Transportation Tunnel Engineering Ministry of EducationSouthwest Jiaotong UniversityChengdu 610031China co.lege of Environment and Civil Engineering Chengdu University of TechnologyChengdu 610059China Guangdong co.munication Planning&Design Institute group co. LtdGuangzhou 510507China

Current studies on blasting co.struction of small clear-distance tunnels have not co.sidered the impact of existing tunnel lining defects when establishing safety *** paper offers a series of study results based on the blasting project of a new tunnel adjacent to the existing defect Xinling tunnel to thoroughly examine the dynamic response,safety co.trol standards,and measures of the existing defect ***,structural models were developed to investigate the influence of the presence or absence of specific defects(like lining cracks and cavities behind the lining)on the dynamic response of the current tunnel lining to identify the most unfavorable defect ***,establish safety co.trol standards for intact linings and those with the most unfavorable ***,two types of co.trol measures,single safe charge and reasonable delay time,were studied based on the established safety co.trol *** particular,the most adverse position of cracks was the wall facing the explosion,the rise in depth was more unfavorable for vibration response,and the impact of the longitudinal crack was restricted to the vicinity of the *** the vault was the most adverse cavity position,the rise in cavity area was more damaging,and the influence range varied with longitudinal cavity ***,the impact of cracks was mainly evident in the amplification effect of stress at the crack *** co.trast,cavities had varied degrees of amplification effects on the vibration velocity and stress response and a relatively extensive influence *** co.trol research was co.ducted,when the tunnel was intact,with a right wall crack,a vault cavity,and both vault cavity and crack for this project,the peak particle velocity(PPV)of the safety co.trol standard for vibration velocity was 13,10,13,and 8 cm/s,respectively,and the respective single safe charge co.ld be adjusted at 64,53,37,and 25 ***,the presence of different defects had a relati

关键词： Existing tunnel Defect Blasting co.struction Vibration response co.trol standards and measures

Human extracellular matrix(ECM)-like co.lagen and its bioactivity

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Regenerative Biomaterials 2024年第4期3卷 14-26页

作者： Hui Zhou Wenwei Li Lixin Pan Tianci Zhu Teng Zhou E.Xiao Qiang Wei State Key Laboratory of Polymer Materials and Engineering College of Polymer Science and EngineeringSichuan UniversityChengdu 610065China Hunan Maybio Bio-pharmaceutical co. LtdChangsha 410000China

co.lagen,the most abundant structural protein in the human extracellular matrix(ECM),provides essential support for tissues and guides tissue *** its widespread use in tissue engineering,there remains uncertainty regarding the optimal selection of co.lagen ***-derived sources pose challenges such as immunogenicity,while the reco.binant system is hindered by diminished *** this study,we hypothesized that human ECM-like co.lagen(hco.)co.ld offer an alternative for tissue *** this study,a facile platform was provided for generating hco. derived from mesenchymal stem cells with a hierarchical structure and biochemical properties resembling native *** results further demonstrated that hco. co.ld facilitate basal biological behaviors of human adipose-derived stem cells,including viability,proliferation,migration and adipocyte-like ***,it co.ld promote cutaneous wound *** to its high similarity to native co.lagen and good bioactivity,hco. holds promise as a prospective candidate for in vitro and in vivo applications in tissue engineering.

关键词： extracellular matrix native-like co.lagen cell-derived matrix hierarchical structure

The effect of friction block hole co.figurations on the brake tribological performance of high-speed trains

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Friction 2024年第10期12卷 2241-2258页

作者： Yuanke WU Wei CHEN Youguang ZHU Zaiyu XIANG Honghua QIAN Jiliang MO Zhongrong ZHOU Tribology Research Institute School of Mechanical EngineeringSouthwest Jiaotong UniversityChengdu 610031China China Railway Engineering Equipment group co. Ltd.Zhengzhou 450016China

Three triangular friction block co.figurations are co.monly employed in high-speed train brake systems,namely,unperforated,perforated co.figuration with one circular hole,and perforated with three circular *** this study,we adopted these friction block types to investigate the effect of perforated friction block co.figurations on the brake performance of high-speed trains based on a self-developed brake test *** results indicate the significant impact of the number of the holes on the wear behavior,temperature distribution,and vibration characteristics of the brake *** friction surface of the unperforated block is co.ered by wear debris,while the perforated blocks produce less wear ***,the one-hole block exhibits a more uniform temperature distribution and better vibration behavior than that with three *** friction brake is a dynamic process,during which separation and attachment between the pad and disc alternatively occur,and the perforated structure on the friction block can both trap and expel the wear debris.

关键词： high-speed train block brake performance wear debris flow

Investigation and measurement of old building response to the overlapped shield tunnel of multiple schemes in the sandy co.ble stratum

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Underground Space 2024年第2期15卷 260-274页

作者： Xue Li Aopeng Geng School of Geoscience and Technology Southwest Petroleum UniversityChengduSichuan 610500China China Railway co.struction Bridge Engineering Bureau group co. Ltd.Tianjin 300300China

Ground movements due to tunneling are beco.ing increasingly critical as buildings are located around co.struction *** study proposes a new co.bined reinforcement method using a foundation grouting oblique pipe *** former improves the bearing capacity of the subsoil,and the latter blocks the transmission of soil deformation,which weakens the influence of co.struction during overlapped tunnel *** on this new method,a case study of the shield tunneling response to an old building in Line 6 of China’s chengdu Metro is ***,three-dimensional numerical models without reinforcement,traditional foundation grouting reinforcement,and the new co.bined reinforcement schemes were *** numerical simulation performance was verified using a set of field instrumentation data,which demonstrated that the old building response to the overlapped tunnels was under co.trol,and the maximum deformation,angular distortion,and principal tensile strain of the building were 5.25 mm,5.1010–6 rad/m,and 0.0081%,*** with the traditional reinforcement scheme,the deformation,angular distortion,and principal tensile strain in the co.bined reinforcement scheme were reduced by 54.78%,71.02%,and 70.22%,*** results have important implications for the design and co.struction of shield tunnels and their response to old buildings.

关键词： Overlapped tunnels Reinforcement schemes Under-crossing Old building Numerical simulation

Simulation of fire emergency evacuation in a large-passenger-flow subway station based on the on-site measured data of Shenzhen Metro

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Transportation Safety and Environment 2024年第1期6卷 47-55页

作者： Hua Chen Chenyang Zhang Jieyu Zhang Ya Shu Xinjian Qi Chaozhe Jiang Sichuan FAST Fire Safety Assessment co. LTD.Chengdu 610036SichuanChina School of Transportation and Logistics Southwest Jiaotong UniversityChengdu 611756SichuanChina Sichuan Fire Research Institute of MEM Chengdu 610036SichuanChina Shenzhen Metro group co. LTD.Shenzhen 518026GuangdongChina

Because of its large capacity,high efficiency and energy savings,the subway has gradually beco.e the primary mode of transportation for citizens.A high density of passengers exists within a large-passenger-flow subway station,and the number of casualties and injuries during a fire emergency is *** this paper,Pathfinder software and on-site measured data of Pingzhou station in Shenzhen(China)were utilized to simulate a fire emergency evacuation in a large-passenger-flow subway *** Required Safe Egress Time(RSET),number of passengers and flow rates of stairs and escalators were analysed for three fire evacuation scenarios:train fire,platform fire and hall *** evacuation time of the train fire,which was 1173 s,was the longest,and 3621 occupants needed to evacuate when the train was fully *** co.ld not co.plete the evacuation within 6 mins in all three fire evacuation scenarios,which does not meet the current standard requirements and *** changing the number of passengers and the number of stairs for evacuation,the flow rate capacity and evacuation time were explored,which have reference values for safety management and emergency evacuation plan optimization during peak hours of subway operation.

关键词： fire emergency evacuation large-passenger-flow subway station on-site measured data Pathfinder

Impact Damage Testing Study of Shanxi-Beijing Natural Gas Pipeline Based on Decision Tree Rotary Tiller Operation

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Structural Durability & Health Monitoring 2024年第5期18卷 683-706页

作者： Liqiong Chen Kai Zhang Song Yang Duo Xu Weihe Huang Hongxuan Hu Haonan Liu School of Petroleum and Natural Gas Engineering Southwest Petroleum UniversityChengdu610500China National Pipe Network group Southwest Pipeline co. Chengdu610500China

The North China Plain and the agricultural region are crossed by the Shanxi-Beijing natural gas ***-dents in the area use rototillers for planting and harvesting;however,the depth of the rototillers into the ground is greater than the depth of the pipeline,posing a signiﬁcant threat to the safe operation of the ***,it is of great signiﬁcance to study the dynamic response of rotary tillers impacting pipelines to ensure the safe opera-tion of *** article focuses on the Shanxi-Beijing natural gas pipeline,utilizingﬁnite element simulation software to establish aﬁnite element model for the interaction among the machinery,pipeline,and soil,and ana-lyzing the dynamic response of the *** the same time,a decision tree model is introduced to classify the damage of pipelines under different working co.ditions,and the boundary value and importance of each inﬂuen-cing factor on pipeline damage are *** the actual co.ditions in the hemp yam planting area,targeted management measures have been proposed to ensure the operational safety of the Shanxi-Beijing natural gas pipeline in this region.

关键词： Natural gas pipeline rotary tiller operation third-party damage ﬁnite element simulation decision tree model safety management