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Dynamic prediction of over-excavation gap due to posture adjustment of shield machine in soft soil

Underground Space 2024年第3期16卷 44-58页

作者： Wenyu Yang Junjie Zheng Rongjun Zhang Sijie Liu Wengang Zhang school of {1. and Hydraulic engineering Huazhong University of Science and TechnologyWuhan 430074China school of {1. engineering Wuhan UniversityWuhan 430072China school of {1. engineering Chongqing UniversityChongqing 400045China

The probability analysis of ground deformation is becoming a trend to estimate and control the risk brought by shield *** gap parameter is regarded as an effective tool to estimate the ground loss of tunnelling in soft *** specifically,x,which is a gap parameter component defined as the over(or insufficient)excavation due to the change in the posture of the shield machine,may contribute more to the uncertainty of the ground ***,the existing uncertainty characterization methods for x have several limitations and cannot explain the uncertain correlations between the relevant *** these lines,to better characterize the uncertainty of x,the multivariate probability distribution was developed in this work and a dynamic prediction was proposed for *** attain this goal,1.23 rings of the field data coming from the shield tunnel between Longqing Road and Baiyun Road in Kunming Metro Line 5 were utilized and 44 parameters including the construction,stratigraphic,and posture parameters were collected to form the *** to the variance filter method,the mutual information method,and the value of the correlation coefficients,the original 44 parameters were reduced to 1. main parameters,which were unit weight,the stoke of the jacks(A,B,C,and D groups),the pressure of the pushing jacks(A,C groups),the chamber pressure,the rotation speed,and the total *** multivariate probability distribution was constructed based on the Johnson system of ***,the distribution was satisfactorily verified in explaining the pairwise correlation between x and other parameters through 2 million simulation *** last,the distribution was used as a prior distribution to update the marginal distribution of x with any group of the relevant parameters *** performance of the dynamic prediction was further validated by the field data of 3 shield tunnel cases.

关键词： Shield tunnel Ground loss Gap parameter Multivariate probability distribution Bayesian updating Dynamic prediction

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2.5-dimension soil seismic response to oblique incident waves based on exact free-field solution

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Frontiers of Structural and civil {1. 2024年第2期18卷 216-235页

作者： Yeongbin Yang Zeyang Zhou Xiaoli Wang Xiongfei Zhang Zhilu Wang school of {1. engineering Chongqing UniversityChongqing 400045China school of {1. engineering and Architecture Chongqing University of Science and TechnologyChongqing 401331China

With the three dimensional(3D)oblique incident waves exactly determined for the free field,the soil seismic responses in both frequency and time domains are studied by the 2.5 dimension(2.5D)finite/infinite element ***,the free-field responses in frequency domain are solved exactly for 3D arbitrary incident P and SV waves,which requires no coordinate conversion or extra effort for SV waves with super-critical incident ***,the earthquake spectra are incorporated by the concept of equivalent seismic forces on the near-field boundary,based only on the displacements input derived for unit ground accelerations of each frequency using the 2.5D *** the asymmetric 2.5D finite/infinite element model adopted,the procedure for soil seismic analysis is *** solutions computed by the proposed method are verified against those of Wolf’s and de Barros and Luco’s and for inversely calculated ground *** interest is that abrupt variation in soil response occurs around the critical angle on the wave propagation plane for SV *** addition,the horizontal displacements attenuate with increasing horizontal incident angle,while the longitudinal ones increase inversely for 3D incident P and SV waves.

关键词： 3D oblique incident wave seismic response analysis 2.5D approach infinite element half-space

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Effect of pipe installation and external load on buried steel pipe responses:Experimental and numerical investigations

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Underground Space 2024年第2期15卷 44-58页

作者： Yadong Zhang Ron Chik-Kwong Wong Jianfeng Chen Wei Su Department of civil {1. Schulich School of EngineeringUniversity of CalgaryCalgaryAB T2N 1N4Canada Department of Geotechnical engineering College of Civil EngineeringTongji UniversityShanghai 200092China

During pipe installation,compacting soil at pipe sides causes an initial pipe deformation which is known as the"peaking"***,in conventional pipe design codes,only pipe deformation caused by vertical overburden is considered while the"peaking"effect is *** this study,a full-scale test was conducted on a Grade X52 steel pipe with a diameter of 600 mm to investigate the impacts of both soil compaction and vertical overburden on pipe *** compaction and external load were found to elongate and shorten the vertical pipe diameter,***"peaking"effect was observed during the installation procedure accompanied by the highest pipe stress measured at the pipe ***,a two-dimensional finite element model was created and validated based on the calculated pipe stresses from the experimental study.A parametric study was performed thereafter to numerically study the impacts of soil water content,pipe wall thickness,compaction pressure,and lift thickness on pipe responses due to soil compaction and external *** increase in the"peaking"effect is observed with increasing soil water content and compaction pressure,while an increase in pipe wall thickness or lift thickness would cause a decrease in the"peaking"effect.

关键词： X52 steel Soil compaction External load Peaking effect Pipe deflection Soil arching

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A novel cylindrical sandwich plate inspired by beetle elytra and its compressive properties

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Science China Technological Sciences 2024年第11期67卷 3465-3476页

作者： SONG YiHeng RUAN SiHan HAO Ning OKABE YoJi school of {1. The University of Tokyo school of {1. engineering Southeast University school of {1. RMIT University Institute of Industrial Science The University of Tokyo

The design and experimental analysis of a semi-cylindrical structure known as the cylindrical beetle elytron plate(CBEP) were presented. Radial compression tests and finite element simulation were performed on CBEPs under 30° and 45° inclined sliding support constraints, with a comparison made to cylindrical honeycomb plate(CHP). The study aims to investigate the superior compression performance and enhancement mechanisms of CBEPs. The results demonstrate that CBEPs exhibit a 1.%–26% increase in specific load-bearing capacity and a 20% increase in specific energy absorption compared with CHPs with equal core wall thickness. Distinct “Z-shaped” tearing failures were observed, with honeycomb plates showing tearing at the center of the honeycomb walls, while beetle elytron plates exhibited tearing along the midline of the trabeculae. Three different stress patterns,including elastic-plastic development stage of arch, plastic hinge node stage, and rigid node stage, were identified and analyzed to explain the mechanical performance improvements and failure characteristics. Considering that structural damage to trabeculae mostly occurs at its junction with the skin, it is recommended to add chamfers to the junctions of CBEP. Therefore, this paper lays the groundwork for the engineering application of CBEP.

关键词： beetle elytron cylindrical beetle elytron plate compression performance failure characteristics enhancement mechanism

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Bending strength degradation of a cantilever plate with surface energy due to partial debonding at the clamped boundary

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Applied Mathematics and Mechanics(English Edition) 2024年第9期45卷 1573-1594页

作者： Zhenliang HU Xueyang ZHANG Xianfang LI school of {1. engineering University of South ChinaHengyang 421001Hunan ProvinceChina school of {1. engineering Central South UniversityChangsha 410075China

This paper investigates the bending fracture problem of a micro/nanoscale cantilever thin plate with surface energy,where the clamped boundary is partially debonded along the thickness *** fundamental mechanical equations for the bending problem of micro/nanoscale plates are given by the Kirchhoff theory of thin plates,incorporating the Gurtin-Murdoch surface elasticity *** two typical cases of constant bending moment and uniform shear force in the debonded segment,the associated problems are reduced to two mixed boundary value *** solving the resulting mixed boundary value problems using the Fourier integral transform,a new type of singular integral equation with two Cauchy kernels is obtained for each case,and the exact solutions in terms of the fundamental functions are determined using the PoincareBertrand *** elastic fields near the debonded tips including the bending moment,effective shear force,and bulk stress components exhibit the oscillatory *** dependence relations among the singular fields,the material constants,and the plate's thickness are analyzed for partially debonded cantilever *** surface energy is neglected,these results reduce the bending fracture of a macroscale partially debonded cantilever plate,which has not been previously reported.

关键词： micro/nanoscale cantilever plate partially debonded bending fracture singular integral equation oscillatory singularity

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Evolution mechanism and quantitative characterization of initial micro-cracks in marble under triaxial compression

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Journal of Zhejiang University-Science A(Applied Physics & engineering) 2024年第7期25卷 586-595页

作者： Zhiliang WANG Songyu LI Jianguo WANG Ao LI Weixiang WANG Chenchen FENG Jingjing FU school of {1. engineering Hefei University of TechnologyHefei230009China school of Mechanics and {1. engineering China University of Mining and TechnologyXuzhou221116China

The initial micro-cracks affect the evolution characteristics of macroscopic deformation and failure of rock but are often ignored in theoretical calculation,numerical simulation,and mechanical *** this study,we propose a quantitative analysis model to investigate the effects of initial micro-cracks on the evolution of marble deformation and *** relationship between the micro-crack propagation and the marble failure characteristics was comprehensively studied by combining theoretical analysis with a micro-computed tomography(micro-CT)scanning *** found that with the increase of confining pressure,the matrix elastic modulus of the marble first increased and then tended to be stable,while the micro-cracks increased *** sensitivity ranges of the marble sample matrix elastic modulus and micro-cracks to confining pressure were 0–30 MPa and 30–50 MPa,*** porosity and Poisson’s ratio decreased *** increasing proportion of internal micro-cracks led to an increase in the sample *** samples presented mainly shear failure under triaxial compression,and the failure angle decreased linearly with the increase of confining *** convergence direction of cracks decreased *** quantitative analysis model could accurately portray the relationship between the overall macroscopic deformation and the deviatoric stress of the samples at the compaction and the linear elastic stages,thus deepening the understanding of the stress–strain behavior of rocks.

关键词： Marble Initial micro-cracks Triaxial compression Constitutive relationship Crack evolution

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Particle aggregation and breakage kinetics in cemented paste backfill

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International Journal of Minerals,Metallurgy and Materials 2024年第9期31卷 1965-1974页

作者： Liuhua Yang Hengwei Jia Aixiang Wu Huazhe Jiao Xinming Chen Yunpeng Kou Mengmeng Dong school of {1. and engineering Henan Polytechnic UniversityJiaozuo 454000China school of {1. and Environmental engineering University of Science and Technology BeijingBeijing 100083China

The macroscopic flow behavior and rheological properties of cemented paste backfill(CPB)are highly impacted by the inherent structure of the paste *** this study,the effects of shear-induced forces and proportioning parameters on the microstructure of fresh CPB were *** size evolution and distribution of floc/agglomerate/particles of paste were monitored by focused beam reflection measuring(FBRM)technique,and the influencing factors of aggregation and breakage kinetics of CPB were *** results indicate that influenced by both internal and external factors,the paste kinetics evolution covers the dynamic phase and the stable *** the mass content or the cement-tailings ratio can accelerate aggregation kinetics,which is advantageous for the rise of average floc ***,the admixture and high shear can improve breaking kinetics,which is beneficial to reduce the average floc *** chord length resembles a normal distribution somewhat,with a peak value of approximate 20μ*** particle disaggregation con-stant(k_(2))is positively correlated with the agitation rate,and k_(2) is five orders of magnitude greater than the particle aggregation constant(k1..The kinetics model depicts the evolution law of particles over time quantitatively and provides a theoretical foundation for the micromechanics of complicated rheological behavior of paste.

关键词： cemented paste backfill particle kinetics admixture rheology

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Prediction model for corrosion rate of low-alloy steels under atmospheric conditions using machine learning algorithms

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International Journal of Minerals,Metallurgy and Materials 2024年第2期31卷 337-350页

作者： Jingou Kuang Zhilin Long school of {1. engineering Xiangtan UniversityXiangtan 411105China

This work constructed a machine learning(ML)model to predict the atmospheric corrosion rate of low-alloy steels(LAS).The material properties of LAS,environmental factors,and exposure time were used as the input,while the corrosion rate as the output.6 dif-ferent ML algorithms were used to construct the proposed *** optimization and filtering,the eXtreme gradient boosting(XG-Boost)model exhibited good corrosion rate prediction *** features of material properties were then transformed into atomic and physical features using the proposed property transformation approach,and the dominant descriptors that affected the corrosion rate were filtered using the recursive feature elimination(RFE)as well as XGBoost *** established ML models exhibited better predic-tion performance and generalization ability via property transformation *** addition,the SHapley additive exPlanations(SHAP)method was applied to analyze the relationship between the descriptors and corrosion *** results showed that the property transformation model could effectively help with analyzing the corrosion behavior,thereby significantly improving the generalization ability of corrosion rate prediction models.

关键词： machine learning low-alloy steel atmospheric corrosion prediction corrosion rate feature fusion

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Migration mechanism of atrazine in the simulated lake icing process at different freezing temperatures based on density function theory

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Journal of Environmental Sciences 2024年第10期144卷 45-54页

作者： Yan Zhang Hao Lin Aixin Yu Xiaozhuang Wang Yucan Liu Tongshuai Liu Chen Zhao Rui Mei school of {1. engineering Yantai UniversityYantai 264005China

Atrazine causes concern due to its resistant to biodegradation and could be accumulated in aquatic organisms,causing pollution in *** study measured the concentration of atrazine in ice and the water under ice through a simulated icing experiment and calculated the distribution coefficient K to characterize its migration ability in the freezing ***,density functional theory(DFT)calculations were employed to expatiate the migration law of atrazine during icing *** to the results,it could release more energy into the environment when atrazine staying in water phase(-1..077 kcal/mol)than staying in ice phase(-1..388 kcal/mol),therefore it was beneficial for the migration of atrazine from ice to *** explains that during the freezing process,the concentration of atrazine in the ice was lower than that in the *** calculations indicated thatwhen the temperature decreases from268 to 248 K,the internal energy contribution of the compound of atrazine and ice molecule(water cluster)decreases at the same vibrational frequency,resulting in an increase in the free energy difference of the compound from-1.7.946 to-1.5.390 kcal/*** demonstrated the diminished migratory capacity of *** study revealed the environmental behavior of atrazine during lake freezing,which was beneficial for the management of atrazine and other pollutants during freezing and environmental protection.

关键词： Density functional theory(DFT) Icing process Atrazine Migration behavior Free energy

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Experimental and numerical study on dynamic mechanical behaviors of shale under true triaxial compression at high strain rate

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International Journal of Mining Science and Technology 2024年第2期34卷 149-165页

作者： Xiaoping Zhou Linyuan Han Jing Bi Yundong Shou school of {1. engineering Wuhan UniversityWuhan 430072China College of civil {1. Guizhou UniversityGuiyang 550025China

High-energy gas fracturing of shale is a novel,high efficacy and eco-friendly mining technique,which is a typical dynamic perturbing *** effectively extract shale gas,it is important to understand the dynamic mechanical properties of *** experiments on shale subjected to true triaxial compression at different strain rates are first conducted in this *** dynamic stress-strain curves,peak strain,peak stress and failure modes of shale are *** results of the study indicate that the intermediate principal stress and the minor principal stress have the significant influence on the dynamic mechanical behaviors,although this effect decreases as the strain rate *** characteristics of compression-shear failure primarily occur in shale subjected to triaxial compression at high strain rates,which distinguishes it from the fragmentation characteristics observed in shale under dynamic uniaxial ***,a numerical three-dimensional Split Hopkinson Pressure Bar(3D-SHPB),which is established by coupling PFC3D and FLAC3D methods,is validated to replicate the laboratory characteristics of *** dynamic mechanical characteristics of shale subjected to different confining stresses are systematically investigated by the coupling PFC3D and FLAC3D *** numerical results are in good agreement with the experimental data.

关键词： Dynamic behaviors True triaxial compression High strain rates Dynamic failure mechanism PFC3D-FLAC3D coupled method

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