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Stress tensor determination by modified hydraulic tests on pre-existing fractures:Method and stress constraints
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作者 Guiyun Gao Chenghu Wang Ke Gao 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第5期1637-1648,共12页
The hydraulic testing of pre-existing fractures(HTPF)is one of the most promising in situ stress measurement methods,particularly for three-dimensional stress tensor determination.However,the stress tensor determinati... The hydraulic testing of pre-existing fractures(HTPF)is one of the most promising in situ stress measurement methods,particularly for three-dimensional stress tensor determination.However,the stress tensor determination based on the HTPF method requires at least six tests or a minimum of 14-15 tests(under different conditions)for reliable results.In this study,we modified the HTPF method by considering the shear stress on each pre-existing fracture,which increased the number of equations for the stress tensor determination and decreased the number of tests required.Different shear stresses were attributed to different fractures by random sampling;therefore,the stress tensors were obtained by searching for the optimal solution using the least squares criterion based on the Monte Carlo method.Thereafter,we constrained the stress tensor based on the tensile strength criterion,compressive strength criterion,and vertical stress constraints.The inverted stress tensors were presented and analyzed based on the tensorial nature of the stress using the Euclidean mean stress tensor.Two stress-measurement campaigns in Weifang(Shandong Province,China)and Mercantour road tunnel(France)were implemented to highlight the validity and efficiency of the modified HTPF(M-HTPF)method.The results showed that the M-HTPF method can be applied for stress tensor inversion using only three to four tests on pre-existing fractures,neglecting the stress gradient.The inversion results were confined to relatively small distribution dispersions and were significantly reliable and stable due to the shear stresses on the fractures and the stress constraints employed.The M-HTPF method is highly feasible and efficient for complete stress tensor determination in a single borehole. 展开更多
关键词 stress tensor Hydraulic tests on pre-existing fractures Mean stress stress constraint Hydraulic fracturing
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Tensor decomposition reveals trans-regulated gene modules in maize drought response
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作者 Jiawen Lu Yuxin Xie +2 位作者 Chunhui Li Jinliang Yang Junjie Fu 《Journal of Genetics and Genomics》 2025年第6期786-798,共13页
When plants respond to drought stress,dynamic cellular changes occur,accompanied by alterations in gene expression,which often act through trans-regulation.However,the detection of trans-acting genetic variants and ne... When plants respond to drought stress,dynamic cellular changes occur,accompanied by alterations in gene expression,which often act through trans-regulation.However,the detection of trans-acting genetic variants and networks of genes is challenged by the large number of genes and markers.Using a tensor decomposition method,we identify trans-acting expression quantitative trait loci(trans-eQTLs)linked to gene modules,rather than individual genes,which were associated with maize drought response.Module-to-trait association analysis demonstrates that half of the modules are relevant to drought-related traits.Genome-wide association studies of the expression patterns of each module identify 286 trans-eQTLs linked to drought-responsive modules,the majority of which cannot be detected based on individual gene expression.Notably,the trans-eQTLs located in the regions selected during maize improvement tend towards relatively strong selection.We further prioritize the genes that affect the transcriptional regulation of multiple genes in trans,as exemplified by two transcription factor genes.Our analyses highlight that multidimensional reduction could facilitate the identification of trans-acting variations in gene expression in response to dynamic environments and serve as a promising technique for high-order data processing in future crop breeding. 展开更多
关键词 MAIZE Drought stress tensor decomposition Gene expression trans-eQTL
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The Grid Search Algorithm of Tectonic Stress Tensor Based on Focal Mechanism Data and Its Application in the Boundary Zone of China, Vietnam and Laos 被引量:66
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作者 Yongge Wan Shuzhong Sheng +2 位作者 Jichao Huang Xiang Li Xin Chen 《Journal of Earth Science》 SCIE CAS CSCD 2016年第5期777-785,共9页
Stress field plays a key role in geodynamics. In this study, an algorithm to determine the stress tensor and its confidence range from focal mechanism data by using grid search method was proposed. The experiment uses... Stress field plays a key role in geodynamics. In this study, an algorithm to determine the stress tensor and its confidence range from focal mechanism data by using grid search method was proposed. The experiment uses artificial focal mechanism data which were generated by extensional, compression and strike-slip stress regime and different level of noise, shows that the precision of the estimated stress tensor based on this algorithm is greatly improved compared with traditional algorithms. This algorithm has three advantages:(1) The global optimal solution of the stress tensor is determined by fine grid search of 1o×1o×1o×0.01 and local minimum value is avoided; (2) precision of focal mechanism data can be considered, i.e., different weight of the focal mechanism data contributes differently to the process of determining stress tensor; (3) the confidence range of the determined stress tensor can be obtained by using F-test. We apply this algorithm in the boundary zone of China, Vietnam and Laos, and obtain the stress field with SSE-NNW compressive stress direction and NEE-SWW extensional stress direction. The stress ratio is 0.6, which shows that the eigen values of the stress tensor are nearly in arithmetic sequence. The stress field in this region is consistent with the left-lateral strike slip of the Dienbien-Lauangphrabang arc fault. The result will be helpful in studying the geological dynamic process in this region. 展开更多
关键词 stress tensor grid search focal mechanism uncertainty.
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Vertical variations of wave-induced radiation stress tensor 被引量:3
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作者 郑金海 阎以新 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2001年第4期597-605,共9页
The distributions of the wave-induced radiation stress tensor over depth are studied by us- ing the linear wave theory, which are divided into three regions, i. e., above the mean water level, be- low the wave trough ... The distributions of the wave-induced radiation stress tensor over depth are studied by us- ing the linear wave theory, which are divided into three regions, i. e., above the mean water level, be- low the wave trough level, and between these two levels. The computational expressions of the wave-in- duced radiation stress tensor at the arbitrary wave angle are established by means of the Eulerian coordi- nate transformation, and the asymptotic forms for deep and shallow water are also presented. The verti- cal variations of a 30°incident wave-induced radiation stress tensor in deep water, intermediate water and shallow water are calculated respectively. The following conclusions are obtained from computations. The wave-induced radiation stress tensor below the wave trough level is induced by the water wave parti- cle velocities only, whereas both the water wave particle velocities and the wave pressure contribute to the tensor above the wave trough level. The vertical variations of the wave-induced radiation stress ten- sor are influenced substantially by the velocity component in the direction of wave propagation. The dis- tributions of the wave-induced radiation stress tensor over depth are nonuiniform and the proportion of the tensor below the wave trough level becomes considerable in the shallow water. From the water surface to the seabed, the reversed variations occur for the predominant tensor components. 展开更多
关键词 Linear wave theory wave-induced radiation stress tensor vertical variation
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Relations between cubic equation, stress tensor decomposition, and von Mises yield criterion
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作者 Haoyuan GUO Liyuan ZHANG +1 位作者 Yajun YIN Yongxin GAO 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2015年第10期1359-1370,共12页
Inspired by Cardano's method for solving cubic scalar equations, the addi- tive decomposition of spherical/deviatoric tensor (DSDT) is revisited from a new view- point. This decomposition simplifies the cubic tenso... Inspired by Cardano's method for solving cubic scalar equations, the addi- tive decomposition of spherical/deviatoric tensor (DSDT) is revisited from a new view- point. This decomposition simplifies the cubic tensor equation, decouples the spher- ical/deviatoric strain energy density, and lays the foundation for the von Mises yield criterion. Besides, it is verified that under the precondition of energy decoupling and the simplest form, the DSDT is the only possible form of the additive decomposition with physical meanings. 展开更多
关键词 Cardano's method Caylay-Hamilton theorem cubic tensor equation decomposition of spherical/deviatoric tensor (DSDT) von Mises yield criterion
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Gedanken Experiment for Fluctuation of Mass of a Graviton, Based on the Trace of GR Stress Energy Tensor-Pre Planckian Conditions that Lead to Gaining of Graviton Mass, and Planckian Conditions That Lead to Graviton Mass Shrinking to 10-62 Grams 被引量:1
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作者 Andrew Walcott Beckwith 《Journal of High Energy Physics, Gravitation and Cosmology》 2016年第1期19-24,共6页
We will be looking at the energy of a graviton, based upon the Stress energy tensor, and from there ascertaining how fluctuations in early universe conditions impact the mass of a graviton. Physically the mass of the ... We will be looking at the energy of a graviton, based upon the Stress energy tensor, and from there ascertaining how fluctuations in early universe conditions impact the mass of a graviton. Physically the mass of the graviton would be shrinking right after Planck time and presumably it would be going to its equilibrium value of about 10<sup>-62</sup> grams, for its present day value. It, graviton mass, would increase up to the Plank time of about 10<sup>-44</sup> seconds. Note that the result that graviton mass shrinks to 10<sup>-62</sup> grams for its present day value works only for relic gravitons. 展开更多
关键词 Heavy Gravity Plank Time stress Energy tensor
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Three-dimensional stress variation characteristics in deep hard rock of CJPL-Ⅱ project based on in-situ monitoring 被引量:1
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作者 Minzong Zheng Shaojun Li +2 位作者 Zejie Feng Huaisheng Xu Yaxun Xiao 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2024年第2期179-195,共17页
In deep hard rock excavation, stress plays a pivotal role in inducing stress-controlled failure. While the impact of excavation-induced stress disturbance on rock failure and tunnel stability has undergone comprehensi... In deep hard rock excavation, stress plays a pivotal role in inducing stress-controlled failure. While the impact of excavation-induced stress disturbance on rock failure and tunnel stability has undergone comprehensive examination through laboratory tests and numerical simulations, its validation through insitu stress tests remains unexplored. This study analyzes the three-dimensional stress changes in the surrounding rock at various depths, monitored during the excavation of B2 Lab in China Jinping Underground Laboratory Phase Ⅱ(CJPL-Ⅱ). The investigation delves into the three-dimensional stress variation characteristics in deep hard rock, encompassing stress components and principal stress. The results indicate changes in both the magnitude and direction of the principal stress during tunnel excavation. To quantitatively describe the degree of stress disturbance, a series of stress evaluation indexes are established based on the distances between stress tensors, including the stress disturbance index(SDI), the principal stress magnitude disturbance index(SDIm), and the principal stress direction disturbance index(SDId). The SDI indicates the greatest stress disturbance in the surrounding rock is 4.5 m from the tunnel wall in B2 Lab. SDIm shows that the principal stress magnitude disturbance peaks at2.5 m from the tunnel wall. SDId reveals that the largest change in principal stress direction does not necessarily occur near the tunnel wall but at a specific depth from it. The established relationship between SDI and the depth of the excavation damaged zone(EDZ) can serve as a criterion for determining the depth of the EDZ in deep hard rock engineering. Additionally, it provides a reference for future construction and support considerations. 展开更多
关键词 Disturbance stress tensor distance stress disturbance index Principal stress direction Underground research laboratory
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STUDY ON THE GENERALIZED PRANDTL-REUSS CONSTITUTIVEEQUATION AND THE COROTATIONALRATES OF STRESS TENSOR
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作者 沈利君 潘立宙 何福保 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1998年第8期735-743,共9页
In this paper, the generalized Prandtl-Reuss (P-R) constitutive equations of elastic-plastic material in the presence of finite deformations through a new approach are studied. It analyzes the generalized P-R equation... In this paper, the generalized Prandtl-Reuss (P-R) constitutive equations of elastic-plastic material in the presence of finite deformations through a new approach are studied. It analyzes the generalized P-R equation based on the material corotational rate and clarifies the puzzling problem of the simple shear stress oscillation mentioned in some literature. The paper proposes a modified relative rotational rate with which to constitute the objective rates of stress in the generalized P-R equation and concludes that the decomposition of total deformation rate into elastic and plastic parts is not necessary in developing the generalized P-R equations. Finally, the stresses of simple shear deformation are worked out. 展开更多
关键词 finite elastic-plastic deformations generalized Prandtl-Reuss constitutive equations the corotational rates of stress tensor simple shear stress oscillation
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Moment tensor and stress inversion solutions of acoustic emissions during compression and tensile fracturing in crystalline rocks
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作者 Zihua Niu Bing Qiuyi Li Omid Moradian 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第10期2778-2786,共9页
We investigate the accuracy and robustness of moment tensor(MT)and stress inversion solutions derived from acoustic emissions(AEs)during the laboratory fracturing of prismatic Barre granite specimens.Pre-cut flaws in ... We investigate the accuracy and robustness of moment tensor(MT)and stress inversion solutions derived from acoustic emissions(AEs)during the laboratory fracturing of prismatic Barre granite specimens.Pre-cut flaws in the specimens introduce a complex stress field,resulting in a spatial and temporal variation of focal mechanisms.Specifically,we consider two experimental setups:(1)where the rock is loaded in compression to generate primarily shear-type fractures and(2)where the material is loaded in indirect tension to generate predominantly tensile-type fractures.In each test,we first decompose AE moment tensors into double-couple(DC)and non-DC terms and then derive unambiguous normal and slip vectors using k-means clustering and an unstructured damped stress inversion algorithm.We explore temporal and spatial distributions of DC and non-DC events at different loading levels.The majority of the DC and the tensile non-DC events cluster around the pre-cut flaws,where macro-cracks later develop.Results of stress inversion are verified against the stress field from finite element(FE)modeling.A good agreement is found between the experimentally derived and numerically simulated stress orientations.To the best of the authors’knowledge,this work presents the first case where stress inversion methodologies are validated by numerical simulations at laboratory scale and under highly heterogeneous stress distributions. 展开更多
关键词 Induced seismicity Acoustic emission(AE) Moment tensor(MT)inversion stress inversion Finite element(FE)modeling
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Explicit Algebraic Stress Model for Three-Dimensional Turbulent Buoyant Flows Derived Using Tensor Representation
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作者 Ronald M. C. So 《Journal of Applied Mathematics and Physics》 2022年第4期1167-1181,共15页
An explicit algebraic stress model (EASM) has been formulated for two-dimensional turbulent buoyant flows using a five-term tensor representation in a prior study. The derivation was based on partitioning the buoyant ... An explicit algebraic stress model (EASM) has been formulated for two-dimensional turbulent buoyant flows using a five-term tensor representation in a prior study. The derivation was based on partitioning the buoyant flux tensor into a two-dimensional and a three-dimensional component. The five-term basis was formed with the two-dimensional component of the buoyant flux tensor. As such, the derived EASM is limited to two-dimensional flows only. In this paper, a more general approach using a seven-term representation without partitioning the buoyant flux tensor is used to derive an EASM valid for two- and three-dimensional turbulent buoyant flows. Consequently, the basis tensors are formed with the fully three-dimensional buoyant flux tensor. The derived EASM has the two-dimensional flow as a special case. The matrices and the representation coefficients are further simplified using a four-term representation. When this four-term representation model is applied to calculate two-dimensional homogeneous buoyant flows, the results are essentially identical with those obtained previously using the two-dimensional component of the buoyant flux tensor. Therefore, the present approach leads to a more general EASM formulation that is equally valid for two- and three-dimensional turbulent buoyant flows. 展开更多
关键词 Explicit Algebraic stress Model Buoyant Flows tensor Representation
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THE STRESS-ENERGY TENSOR AND POHOZAEV'S IDENTITY FOR SYSTEMS
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作者 N.D.Alikakos A.C.Faliagas 《Acta Mathematica Scientia》 SCIE CSCD 2012年第1期433-439,共7页
Utilizing stress-energy tensors which allow for a divergence-free formulation, we establish Pohozaev's identity for certain classes of quasilinear systems with variational structure.
关键词 calculus of variations stress-energy tensor p-Lapacian minimal surface
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Modeling Reynolds stress anisotropy invariants via machine learning
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作者 Xianglin Shan Xuxiang Sun +2 位作者 Wenbo Cao Weiwei Zhang Zhenhua Xia 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2024年第6期50-63,共14页
The presentation and modeling of turbulence anisotropy are crucial for studying large-scale turbulence structures and constructing turbulence models.However,accurately capturing anisotropic Reynolds stresses often rel... The presentation and modeling of turbulence anisotropy are crucial for studying large-scale turbulence structures and constructing turbulence models.However,accurately capturing anisotropic Reynolds stresses often relies on expensive direct numerical simulations(DNS).Recently,a hot topic in data-driven turbulence modeling is how to acquire accurate Reynolds stresses by the Reynolds-averaged Navier-Stokes(RANS)simulation and a limited amount of data from DNS.Many existing studies use mean flow characteristics as the input features of machine learning models to predict high-fidelity Reynolds stresses,but these approaches still lack robust generalization capabilities.In this paper,a deep neural network(DNN)is employed to build a model,mapping from tensor invariants of RANS mean flow features to the anisotropy invariants of high-fidelity Reynolds stresses.From the aspects of tensor analysis and input-output feature design,we try to enhance the generalization of the model while preserving invariance.A functional framework of Reynolds stress anisotropy invariants is derived theoretically.Complete irreducible invariants are then constructed from a tensor group,serving as alternative input features for DNN.Additionally,we propose a feature selection method based on the Fourier transform of periodic flows.The results demonstrate that the data-driven model achieves a high level of accuracy in predicting turbulence anisotropy of flows over periodic hills and converging-diverging channels.Moreover,the well-trained model exhibits strong generalization capabilities concerning various shapes and higher Reynolds numbers.This approach can also provide valuable insights for feature selection and data generation for data-driven turbulence models. 展开更多
关键词 Reynolds stress Anisotropy invariant tensor analysis Machine learning
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粗粒土力学特性大型平面应变试验研究 被引量:2
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作者 姜景山 左永振 +3 位作者 程展林 黄鑫 张超 王志华 《长江科学院院报》 北大核心 2025年第1期129-135,143,共8页
土石坝填料一般处于平面应变状态,目前填料力学特性研究基本采用大型三轴试验。由于三轴应力状态下中主应力等于小主应力,平面应变状态下大坝填料的力学性能会被低估。为充分认识填料潜能,科学设计和合理评估土石坝,有必要对填料开展平... 土石坝填料一般处于平面应变状态,目前填料力学特性研究基本采用大型三轴试验。由于三轴应力状态下中主应力等于小主应力,平面应变状态下大坝填料的力学性能会被低估。为充分认识填料潜能,科学设计和合理评估土石坝,有必要对填料开展平面应变试验研究。应用大型真三轴仪对填料进行了大型平面应变试验,共开展了4种不同初始干密度的粗粒土平面应变各向等压固结排水剪切试验。结果表明:应力-应变关系主要为应变硬化型,应力曲线呈爬升型,体变表现为剪缩。某一小主应力下,大小主应力之差的最大值随初始干密度的增大呈线性增大;初始干密度一定时,大小主应力之差的最大值与小主应力呈线性关系增大。初始剪切阶段,小主应力一定时,偏应力与球应力之比曲线斜率随初始干密度的增大而增大,随剪切变形的发展,不同初始干密度的应力比曲线逐渐趋于接近。偏应力随球应力的增大单调增加则对应应变硬化型,若偏应力随球应力的增大先增加后减小则对应应变软化型。相同小主应力时,初始弹性模量随初始干密度的增大而增大,近似呈线性关系;某一初始干密度下,初始弹性模量随小主应力的增大基本呈线性关系增大。中主应力系数随大主应力方向应变的增大而增大,曲线形态呈三折线形,初始剪切阶段增长较为缓慢,随剪切变形的增大增长相对加快并呈线性关系增大,如曲线末端下弯为应变硬化型,曲线末端上翘为应变软化型。 展开更多
关键词 粗粒土 大型平面应变试验 力学特性 主应力 偏应力 球应力 大型真三轴仪
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剥蚀区影响下大巷布置优化及煤柱稳定性研究 被引量:1
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作者 解盘石 张波 +5 位作者 黄宝发 张浩 路贝 雷二辉 王茜 刘鑫 《采矿与岩层控制工程学报》 北大核心 2025年第3期166-182,共17页
为研究浅埋煤层在剥蚀区影响下大巷布置优化及煤柱稳定性,以瑶渠煤矿西采区回风大巷为研究对象,采用理论分析、数值模拟和现场工程验证等方法,研究了剥蚀区影响下巷道变形破坏特征与能量演化规律,分析了在偏应力屈服准则和能量判据下不... 为研究浅埋煤层在剥蚀区影响下大巷布置优化及煤柱稳定性,以瑶渠煤矿西采区回风大巷为研究对象,采用理论分析、数值模拟和现场工程验证等方法,研究了剥蚀区影响下巷道变形破坏特征与能量演化规律,分析了在偏应力屈服准则和能量判据下不同尺寸煤柱的破坏情况,确定了巷道布置优化后合理的煤柱尺寸。结果表明:剥蚀区会使围岩应力增加、应变能积聚,致使巷道围岩变形破坏加剧,坚硬岩层受扰动时应变能变化较小,但不会隔断能量的传递,而较软煤岩体中会产生较大的应变能改变。巷道布置优化后,掘进过程中煤柱内偏应力与应变能呈先递增再稳定最后递减趋势,巷间煤柱小于9 m时,煤柱内偏应力与能量曲线均呈“钟形”分布,且均大于屈服破坏的极限值;煤柱宽度为10~13 m时,偏应力与能量曲线转变为“马鞍形”,煤柱内部小于屈服极限区域逐渐增加,承载能力逐步提高;煤柱宽度大于13 m时,回风大巷与剥蚀区距离过近,其间煤体在剥蚀区和回风大巷双重应力和能量叠加下产生失稳破坏。最后,综合确定煤柱合理尺寸范围为10~12 m,考虑保持煤柱稳定性同时减小剥蚀区的影响,采用10 m煤柱进行工程实践,监测结果表明巷道整体变形量较小,围岩稳定性控制较好。 展开更多
关键词 剥蚀区 巷道布置优化 煤柱宽度 偏应力 应变能演化
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考虑轴向应力作用的巷道偏应力分布与破坏特征关系 被引量:2
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作者 刘洪涛 韩子俊 +5 位作者 陈子晗 郭林峰 梁嘉璐 韩洲 刘勤裕 姬越 《煤炭学报》 北大核心 2025年第2期824-844,共21页
通过理论分析建立了考虑巷道轴向应力影响的全平面应变问题三维模型,推导了三维应力场下巷道围岩第二不变偏应力J_(2)隐式解析解,分析了巷道围岩在弹性状态和塑性状态时不同水平侧压和轴向侧压应力环境下的J_(2)分布大小及形态演化规律... 通过理论分析建立了考虑巷道轴向应力影响的全平面应变问题三维模型,推导了三维应力场下巷道围岩第二不变偏应力J_(2)隐式解析解,分析了巷道围岩在弹性状态和塑性状态时不同水平侧压和轴向侧压应力环境下的J_(2)分布大小及形态演化规律。基于Kastner求解法得出了三维应力场下的巷道围岩塑性区边界隐式解,并运用数学与数值分析方法研究了不同应力条件下巷道围岩塑性区分布特征。建立了第二不变偏应力J_(2)与围岩塑性区形态的相互对应关系,揭示了巷道围岩的变形破坏机制。以寸草塔二矿31205工作面回风巷为工程背景,对叠加采动作用下的巷道围岩J_(2)及塑性区分布特征展开研究,量化了非对称变形破坏特征,寻求了支护阻力与J_(2)的相互作用关系,提出了叠加采动巷道的稳定性控制技术。研究结果表明:固定轴向侧压值变化水平侧压值的情况下,J_(2)和塑性区形态分布特征呈现“圆形−类椭圆形−类蝶形”的演化过程。固定水平侧压值变化轴向侧压值的情况下,J_(2)和塑性区形态保持不变。轴向应力的改变对塑性区形态的影响较小,但会对塑性区尺寸产生较大影响。巷道围岩J_(2)的集中程度越大,围岩的变形破坏程度越大,J_(2)的分布形态一定程度上决定了塑性区的破坏形态。31205回风巷在叠加采动影响下处于高偏应力J_(2)环境,且形成了向采空区一侧旋转的应力分布特征,致使巷道形成非对称大变形破坏。支护阻力的提高对巷道围岩的偏应力J_(2)的降低作用有限,仅依靠锚杆(索)无法完全对巷道围岩进行稳定控制。基于上述研究,提出了超前强力支架+锚杆(索)支护系统的组合控制技术,现场应用效果良好。 展开更多
关键词 巷道围岩控制 偏应力第二不变量J_(2) 塑性区形态 围岩破坏机制 重复采动
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弹性阶段钢筋的应力⁃磁导率本构模型研究
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作者 江胜华 何峻峰 +1 位作者 孙伟贺 侯建国 《武汉大学学报(工学版)》 北大核心 2025年第10期1588-1595,共8页
针对钢筋应力与磁导率的理论模型仍不完善、钢筋应力的磁场测试试验中存在难以分离的环境干扰磁场、钢筋磁信号随应力的变化规律中反转现象仍不明确的现状,推导了弹性阶段钢筋应力与磁导率的本构模型,采用有限元计算了弹性阶段钢筋的磁... 针对钢筋应力与磁导率的理论模型仍不完善、钢筋应力的磁场测试试验中存在难以分离的环境干扰磁场、钢筋磁信号随应力的变化规律中反转现象仍不明确的现状,推导了弹性阶段钢筋应力与磁导率的本构模型,采用有限元计算了弹性阶段钢筋的磁场梯度与应力的变化规律,并研制了无磁试验系统,通过试验对推导的应力与磁导率的本构模型及有限元计算进行了比较验证。结果表明:当0≤σ≤175.9 MPa(应力反转点)时,钢筋的相对磁导率及磁场梯度随着应力的增加而增加;当175.9 MPa≤σ≤584.3 MPa(屈服强度)时,钢筋的相对磁导率及磁场梯度随着应力的增加而减小;当σ=175.9 MPa时,钢筋的相对磁导率及磁场梯度均达到最大值。由钢筋磁场梯度绝对值的平均值随应力的变化曲线可知,试验实测值与有限元计算值的误差的平均值、标准差分别为7.08%、6.21%。试验值与有限元计算值基本一致,可为钢筋应力的磁场监测提供参考。 展开更多
关键词 钢筋 弹性阶段 力-磁效应 磁场梯度张量 磁导率
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2023年平原M_(S)5.5地震矩张量反演及发震构造
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作者 许英才 郭祥云 《地震地质》 北大核心 2025年第1期284-305,共22页
2023年8月6日山东省德州市平原县发生M_(S)5.5地震,震中周边河北、河南、天津及北京等多地震感明显,该地震打破了震中50km范围内无M≥5.0地震的历史记录,并引起了社会和地震工作者的广泛关注。基于震中周边的区域地震台网地震资料,文中... 2023年8月6日山东省德州市平原县发生M_(S)5.5地震,震中周边河北、河南、天津及北京等多地震感明显,该地震打破了震中50km范围内无M≥5.0地震的历史记录,并引起了社会和地震工作者的广泛关注。基于震中周边的区域地震台网地震资料,文中采用gCAP方法反演了平原M_(S)5.5地震的矩张量解,利用双差定位方法对平原M_(S)5.5地震序列中M_(L)≥1.0的地震进行了重定位,基于震源机制与区域应力场的数值关系模拟方法计算了平原M_(S)5.5地震震源机制节面的相对剪应力和正应力,根据重定位结果拟合了断层面,并分析了该平原地震序列的发震构造。结果显示:1)平原M_(S)5.5地震的地震矩(M_(0))为1.97×10^(17)N·m、矩震级为M_(W)5.5,矩心深度16km,矩张量解M_(rr)、M_(tt)、M_(pp)、M_(rt)、M_(rp)、M_(tp)分别为-0.129、1.194、-0.459、0.009、0.336、0.245,其最佳双力偶(DC)、各向同性(ISO)、补偿线性向量偶极(CLVD)成分占全矩张量解的92.40%、6.25%、1.35%,最佳双力偶解的节面Ⅰ的走向、倾角、滑动角分别为222°、71°、-156°,节面Ⅱ的走向、倾角、滑动角为124°、67°、-21°,P轴方位84°、倾伏角为30°,显示该地震为走滑型天然地震事件且略带少量的正断分量,震源区主压应力呈现近NEE-SWW向的推挤特征,这与华北平原的区域应力场主压应力方向基本一致。2)重定位后的平原M_(S)5.5地震序列震中主要呈NE-SW向优势展布,长约15km、宽约5km,M_(L)≥1.0地震的震源深度主要集中在8~22km之间,平均深度为15.4km,震源深度剖面显示可能的发震构造倾向NW。3)现今应力场与震源机制数值关系模拟显示,平原地区的应力体系在平原M_(S)5.5地震震源机制节面Ⅰ和节面Ⅱ产生的相对剪应力分别为0.860和0.689。断层面拟合揭示平原地震发震断层具有右旋走滑的运动性质。4)结合已有研究分析认为,平原M_(S)5.5地震的震源机制节面Ⅰ为其可能的发震破裂面,主震发震断层倾角为71°,地震序列主要发震构造为走向SW、倾向NW的高倾角隐伏断层,平原M_(S)5.5地震是由于华北平原NEE-SWW向区域应力场主压应力的作用下,应力得到了充分积累,在剪应力的最优释放节面破裂引起的一次略具正断分量的右旋走滑型地震事件。 展开更多
关键词 平原M_(S)5.5地震 矩张量反演 重定位 相对剪应力 发震构造
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基于有效应力正负分解的木材三维弹塑性损伤模型
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作者 王明谦 《土木工程学报》 北大核心 2025年第2期25-32,共8页
准确描述木材的损伤演化过程对于木结构的制造、施工和后期维护具有重要意义。为合理反映木材不同方向损伤的相互影响,根据热力学第二定律建立了的双标量弹塑性损伤模型。采用Hill屈服准则和Voce模型更新木材的有效应力和塑性应变。根... 准确描述木材的损伤演化过程对于木结构的制造、施工和后期维护具有重要意义。为合理反映木材不同方向损伤的相互影响,根据热力学第二定律建立了的双标量弹塑性损伤模型。采用Hill屈服准则和Voce模型更新木材的有效应力和塑性应变。根据有效应力正负分解和损伤能释放率识别受拉和受压不同的损伤起始点。通过2种标量形式的损伤变量分别追踪木材受拉和受压损伤演化过程。通过编写用户自定义子程序UMAT将本构模型嵌入商业有限元软件ABAQUS。根据已有木材单轴和双轴受力试验结果对本构模型进行验证。计算结果表明,弹塑性损伤本构模型能够准确表征木材的非线性受力行为。基于有效应力正负分解和能量释放率的损伤识别方法能够合理表征木材在双轴受拉和双轴受压状态下的强度包络线。 展开更多
关键词 木材 弹塑性损伤模型 有效应力正负分解 热力学
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侏罗系陆相页岩各向异性动静态弹性参数建模 被引量:1
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作者 刘卫华 王洋 +4 位作者 陈祖庆 陈超 沈珲 张方南 仉涛 《地球物理学报》 北大核心 2025年第1期213-228,共16页
动、静态弹性参数转换关系对陆相页岩储层压裂改造、钻井方案设计、地应力预测等地质工程问题有重要意义.但页岩的本征各向异性及动、静态弹性参数的强压力依赖性对建立各向异性背景下的动、静弹性参数转换模型提出了新的挑战.本次实验... 动、静态弹性参数转换关系对陆相页岩储层压裂改造、钻井方案设计、地应力预测等地质工程问题有重要意义.但页岩的本征各向异性及动、静态弹性参数的强压力依赖性对建立各向异性背景下的动、静弹性参数转换模型提出了新的挑战.本次实验研究基于10组四川盆地侏罗系陆相页岩样品的各向异性动、静态弹性参数联合测试,建立了模拟原位有效应力条件下各向异性动、静态弹性参数建模工作流程.多级偏应力循环实验结果表明:无论是在垂直还是平行层理方向,动态杨氏模量和泊松比均系统性地大于对应的静态杨氏模量和泊松比,并且动、静态弹性参数都表现出明显的压力依赖性.根据围压为20 MPa时的实测数据,直接建立了垂直层理方向模拟原位应力的动、静杨氏模量和泊松比转换关系.在此基础上,假定动态、静态杨氏模量各向异性的关系不依赖于所施加应力大小,建立了动、静态杨氏模量各向异性强度之间的线性关系,进而间接获得了模拟原位应力条件下的平行层理方向静态杨氏模量.各向异性背景下的动、静态弹性参数转换模型可将测井或地震数据转换为原位有效应力条件下的静态弹性参数,并可为各向异性背景下页岩储层地应力预测提供指导. 展开更多
关键词 各向异性 杨氏模量 泊松比 动静态转换 多级偏应力循环
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张家口-渤海地震带震源机制一致性时空特征
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作者 马旭东 王想 +1 位作者 周依 马栋 《大地测量与地球动力学》 北大核心 2025年第7期676-680,711,共6页
利用张家口-渤海地震带2009-01—2023-02的708个M_(L)≥2.0地震震源机制解资料进行反演,得到该区域震源机制一致性时空分布特征和主应力轴方位角;结合唐山马家沟矿井水位资料,分析该区域应力状态。结果表明,张家口-渤海地震带西段与中... 利用张家口-渤海地震带2009-01—2023-02的708个M_(L)≥2.0地震震源机制解资料进行反演,得到该区域震源机制一致性时空分布特征和主应力轴方位角;结合唐山马家沟矿井水位资料,分析该区域应力状态。结果表明,张家口-渤海地震带西段与中段主应力轴方位角自1978年以来一直呈现相反变化趋势,东段主应力轴方位角在1966—2009年一直呈现增大的变化趋势,2009年之后略有减小;张家口-渤海地震带M_(L)≥4.0地震大多位于应力张量方差低值区;张家口-渤海地震带东段约70%的M_(L)≥3.0地震的震前misfit值下降,马家沟矿井周边几次M_(L)≥4.0地震前都发生应力增强现象。 展开更多
关键词 张家口-渤海地震带 震源机制 应力场 应力张量方差 垂向应力
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