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Semi-analytical solution for mechanical analysis of tunnels crossing strike-slip fault zone considering nonuniform fault displacement and uncertain fault plane position
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作者 YANG Heng-hong WANG Ming-nian +1 位作者 YU Li ZHANG Xiao 《Journal of Central South University》 SCIE EI CAS CSCD 2024年第6期2116-2136,共21页
The tunnel subjected to strike-slip fault dislocation exhibits severe and catastrophic damage.The existing analysis models frequently assume uniform fault displacement and fixed fault plane position.In contrast,post-e... The tunnel subjected to strike-slip fault dislocation exhibits severe and catastrophic damage.The existing analysis models frequently assume uniform fault displacement and fixed fault plane position.In contrast,post-earthquake observations indicate that the displacement near the fault zone is typically nonuniform,and the fault plane position is uncertain.In this study,we first established a series of improved governing equations to analyze the mechanical response of tunnels under strike-slip fault dislocation.The proposed methodology incorporated key factors such as nonuniform fault displacement and uncertain fault plane position into the governing equations,thereby significantly enhancing the applicability range and accuracy of the model.In contrast to previous analytical models,the maximum computational error has decreased from 57.1%to 1.1%.Subsequently,we conducted a rigorous validation of the proposed methodology by undertaking a comparative analysis with a 3D finite element numerical model,and the results from both approaches exhibited a high degree of qualitative and quantitative agreement with a maximum error of 9.9%.Finally,the proposed methodology was utilized to perform a parametric analysis to explore the effects of various parameters,such as fault displacement,fault zone width,fault zone strength,the ratio of maximum fault displacement of the hanging wall to the footwall,and fault plane position,on the response of tunnels subjected to strike-slip fault dislocation.The findings indicate a progressive increase in the peak internal forces of the tunnel with the rise in fault displacement and fault zone strength.Conversely,an augmentation in fault zone width is found to contribute to a decrease in the peak internal forces.For example,for a fault zone width of 10 m,the peak values of bending moment,shear force,and axial force are approximately 46.9%,102.4%,and 28.7% higher,respectively,compared to those observed for a fault zone width of 50 m.Furthermore,the position of the peak internal forces is influenced by variations in the ratio of maximum fault displacement of the hanging wall to footwall and the fault plane location,while the peak values of shear force and axial force always align with the fault plane.The maximum peak internal forces are observed when the footwall exclusively bears the entirety of the fault displacement,corresponding to a ratio of 0:1.The peak values of bending moment,shear force,and axial force for the ratio of 0:1 amount to approximately 123.8%,148.6%,and 111.1% of those for the ratio of 0.5:0.5,respectively. 展开更多
关键词 strike-slip fault tunnel engineering semi-analytical solution fault zone width nonuniform fault displacement uncertain fault plane position
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Analytical solution for the effective elastic properties of rocks with the tilted penny-shaped cracks in the transversely isotropic background
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作者 Zheng-Qian Ma Xing-Yao Yin +2 位作者 Zhao-Yun Zong Yuan-Yuan Tan Ya-Ming Yang 《Petroleum Science》 SCIE EI CAS CSCD 2024年第1期221-243,共23页
Seismic prediction of cracks is of great significance in many disciplines,for which the rock physics model is indispensable.However,up to now,multitudinous analytical models focus primarily on the cracked rock with th... Seismic prediction of cracks is of great significance in many disciplines,for which the rock physics model is indispensable.However,up to now,multitudinous analytical models focus primarily on the cracked rock with the isotropic background,while the explicit model for the cracked rock with the anisotropic background is rarely investigated in spite of such case being often encountered in the earth.Hence,we first studied dependences of the crack opening displacement tensors on the crack dip angle in the coordinate systems formed by symmetry planes of the crack and the background anisotropy,respectively,by forty groups of numerical experiments.Based on the conclusion from the experiments,the analytical solution was derived for the effective elastic properties of the rock with the inclined penny-shaped cracks in the transversely isotropic background.Further,we comprehensively analyzed,according to the developed model,effects of the crack dip angle,background anisotropy,filling fluid and crack density on the effective elastic properties of the cracked rock.The analysis results indicate that the dip angle and background anisotropy can significantly either enhance or weaken the anisotropy degrees of the P-and SH-wave velocities,whereas they have relatively small effects on the SV-wave velocity anisotropy.Moreover,the filling fluid can increase the stiffness coefficients related to the compressional modulus by reducing crack compliance parameters,while its effects on shear coefficients depend on the crack dip angle.The increasing crack density reduces velocities of the dry rock,and decreasing rates of the velocities are affected by the crack dip angle.By comparing with exact numerical results and experimental data,it was demonstrated that the proposed model can achieve high-precision estimations of stiffness coefficients.Moreover,the assumption of the weakly anisotropic background results in the consistency between the proposed model and Hudson's published theory for the orthorhombic rock. 展开更多
关键词 Effective elastic property Tilted crack Transverse isotropy Analytical solution Crack opening displacement
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Effect of polymer solution structure on displacement efficiency 被引量:9
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作者 Shi Leiting Chen Lei +4 位作者 Ye Zhongbin Zhou Wei Zhang Jian Yang Jie Jin Jianbo 《Petroleum Science》 SCIE CAS CSCD 2012年第2期230-235,共6页
In this paper, a series of experiments, including atomic force microscope (AFM), environmental scanning electron microscope (ESEM), and core displacement tests were conducted to investigate the effect of polymer s... In this paper, a series of experiments, including atomic force microscope (AFM), environmental scanning electron microscope (ESEM), and core displacement tests were conducted to investigate the effect of polymer solution structure on solution properties and oil displacement efficiency. The results show that in the HPAM solution polymer coils were formed and then aggregated into a loose structure, while the HAP2010 solution formed a strong network structure, which would significantly improve the solution viscosity and flow resistance so as to upgrade the capacity of piston-like oil displacement in highly permeable porous media. Meanwhile, the retention of the HAP2010 solution at pore throats were also enhanced, which could reduce water production during subsequent water flooding and enlarge the swept volume during polymer flooding. Therefore, enhancing the interaction among polymer molecules is an effective way to improve the displacement efficiency of polymer solutions in heavy oil reservoirs with high permeability. 展开更多
关键词 POLYMER solution structure loosely-aggregated structure network structure displacement efficiency
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APPLICATION OF THE METHOD OF THE RECIPROCAL THEOREM TO FINDING DISPLACEMENT SOLUTIONS OF CUBES
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作者 付宝连 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1989年第4期309-320,共12页
In this paper the method of reciprocal theorem is extended to find solutions of three-D problems of elasticity.First we give the basic solution of the cube with six surfaces fixed as the basic system and then using th... In this paper the method of reciprocal theorem is extended to find solutions of three-D problems of elasticity.First we give the basic solution of the cube with six surfaces fixed as the basic system and then using the reciprocal theorem between the basic system acted on by unit concentrated loads and the actual system with prescribed surface displacements, we find displacement solution of the actual system. 展开更多
关键词 CUBE OO CO APPLICATION of THE METHOD of THE RECIPROCAL THEOREM TO FINDING displacement solutionS of CUBES
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Molecular Dynamics Simulations of Displacement Cascade in Ni-Based Concentrated Solid Solution Alloys
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作者 Chaoquan Zhao Rongxuan Xie +4 位作者 Chuanlong Xu Xiaobao Tian Qingyuan Wang Wentao Jiang Haidong Fan 《Acta Mechanica Solida Sinica》 SCIE EI CSCD 2024年第1期82-89,共8页
Single-phase concentrated solid solution alloys(SP-CSAs),including high-entropy alloys,have received extensive attention due to their excellent irradiation resistance.In this work,displacement cascade simulations are ... Single-phase concentrated solid solution alloys(SP-CSAs),including high-entropy alloys,have received extensive attention due to their excellent irradiation resistance.In this work,displacement cascade simulations are conducted using the molecular dynamics method to study the evolution of defects in Ni-based SP-CSAs.Compared with pure Ni,the NiCr,NiCo,and NiCu alloys exhibit a larger number of Frankel pairs(FPs)in the thermal peak stage,but a smaller number of surviving FPs.However,the NiFe alloy displays the opposite phenomenon.To explain these different observations for NiFe and other alloys,the formation energy and migration energy of interstitials/vacancies are calculated.In the NiFe alloy,both the formation energy and migration energy barrier are higher.On the other hand,in NiCr and other alloys,the formation energy of interstitials/vacancies is lower,as is the migration energy barrier of interstitials.The energy analysis agrees well with previous observations.The present work provides new insights into the mechanism behind the irradiation resistance of binary Ni-based SP-CSAs. 展开更多
关键词 Molecular dynamics simulation displacement cascade Point defect Ni-based concentrated solid solution alloys
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Modified (2+1)-dimensional displacement shallow water wave system and its approximate similarity solutions 被引量:4
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作者 刘萍 付培凯 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第9期30-36,共7页
Recently, a new (2+1)-dimensional shallow water wave system, the (2+1)-dlmenslonal displacement shallow water wave system (2DDSWWS), was constructed by applying the variational principle of the analytic mechan... Recently, a new (2+1)-dimensional shallow water wave system, the (2+1)-dlmenslonal displacement shallow water wave system (2DDSWWS), was constructed by applying the variational principle of the analytic mechanics in the Lagrange coordinates. The disadvantage is that fluid viscidity is not considered in the 2DDSWWS, which is the same as the famous Kadomtsev-Petviashvili equation and Korteweg-de Vries equation. Applying dimensional analysis, we modify the 2DDSWWS and add the term related to the fluid viscidity to the 2DDSWWS. The approximate similarity solutions of the modified 2DDSWWS (M2DDSWWS) is studied and four similarity solutions are obtained. For the perfect fluids, the coefficient of kinematic viscosity is zero, then the M2DDSWWS will degenerate to the 2DDSWWS. 展开更多
关键词 modified (2+1)-dimensional displacement shallow water wave system viscidity approx-imate similarity solutions Kadomtsev-Petviashvili equation
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A priliminary study on the sequence characteristics and focal mechanism solution of the Jiashi strong earthquake swarm 被引量:2
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作者 XIN YANG GUO YING GAO Seismological Bureau of Xinjiang Uygur Autonomous Region, rümqi 830011, China 《Acta Seismologica Sinica(English Edition)》 CSCD 1998年第6期16-23,共8页
The sequence characteristics and focal mechanism solution of the Jiashi, Xinjiang strong earthquake swarm are analyzed and studied in this paper. The result shows that before the M S=6.6 earthquake, value h o... The sequence characteristics and focal mechanism solution of the Jiashi, Xinjiang strong earthquake swarm are analyzed and studied in this paper. The result shows that before the M S=6.6 earthquake, value h of sequence frequency attenuation coefficient was less than 1, then value h was more than 1. Before occurrence of M S6.0 earthquakes the energy is released either in a continuously strengthened way or a sharply strengthened way, and before M S5.0 earthquakes the sequence frequency shows calm. The study on the focal mechanism solution of the strong earthquake swarm shows that the source faults are mainly in a right lateral, strike slip way and the faults have characteristics of tensor shear. 展开更多
关键词 earthquake swarm sequence characteristics focal mechanism solution focal displacement feature JIASHI
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Displacement of surrounding rock in a deep circular hole considering double moduli and strength-stiffness degradation 被引量:2
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作者 Zenghui ZHAO WeiSUN +2 位作者 Shaojie CHEN Yuanhui FENG Weiming WANG 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2020年第12期1847-1860,共14页
The problem of cavity stability widely exists in deep underground engineering and energy exploitation.First,the stress field of the surrounding rock under the uniform stress field is deduced based on a post-peak stren... The problem of cavity stability widely exists in deep underground engineering and energy exploitation.First,the stress field of the surrounding rock under the uniform stress field is deduced based on a post-peak strength drop model considering the rock’s characteristics of constant modulus and double moduli.Then,the orthogonal non-associative flow rule is used to establish the displacement of the surrounding rock under constant modulus and double moduli,respectively,considering the stiffness degradation and dilatancy effects in the plastic region and assuming that the elastic strain in the plastic region satisfies the elastic constitutive relationship.Finally,the evolution of the displacement in the surrounding rock is analyzed under the effects of the double modulus characteristics,the strength drop,the stiffness degradation,and the dilatancy.The results show that the displacement solutions of the surrounding rock under constant modulus and double moduli have a unified expression.The coefficients of the expression are related to the stress field of the original rock,the elastic constant of the surrounding rock,the strength parameters,and the dilatancy angle.The strength drop,the stiffness degradation,and the dilatancy effects all have effects on the displacement.The effects can be characterized by quantitative relationships. 展开更多
关键词 deep rock double moduli strength-stiffness degradation circular hole displacement solution
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THE MORE GENERAL DISPLACEMENT SOLUTIONS FOR THE PLANE ELASTICITY PROBLEMS
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作者 袁镒吾 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1993年第3期247-252,共6页
In this paper, the author obtains the more general displacement solutions for the isotropic plane elasticity problems. The general solution obtained in ref. [ 1 ] is merely the particular case of this paper, In compar... In this paper, the author obtains the more general displacement solutions for the isotropic plane elasticity problems. The general solution obtained in ref. [ 1 ] is merely the particular case of this paper, In comparison with ref. [1], the general solutions of this paper contain more arbitrary constants. Thus they may satisfy more boundary conditions. 展开更多
关键词 plane elasticity problem displacement solutions biharmonic equation
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Governing equations and numerical solutions of tension leg platform with finite amplitude motion
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作者 曾晓辉 沈晓鹏 吴应湘 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2007年第1期37-49,共13页
It is demonstrated that when tension leg platform (TLP) moves with finite amplitude in waves, the inertia force, the drag force and the buoyancy acting on the platform are nonlinear functions of the response of TLP,... It is demonstrated that when tension leg platform (TLP) moves with finite amplitude in waves, the inertia force, the drag force and the buoyancy acting on the platform are nonlinear functions of the response of TLP, The tensions of the tethers are also nonlinear functions of the displacement of TLP. Then the displacement, the velocity and the acceleration of TLP should be taken into account when loads are calculated. In addition, equations of motions should be set up on the instantaneous position. A theo- retical model for analyzing the nonlinear behavior of a TLP with finite displacement is developed, in which multifold nonlinearities are taken into account, i.e., finite displace- ment, coupling of the six degrees of freedom, instantaneous position, instantaneous wet surface, free surface effects and viscous drag force, Based on the theoretical model, the comprehensive nonlinear differential equations are deduced. Then the nonlinear dynamic analysis of ISSC TLP in regular waves is performed in the time domain. The degenerative linear solution of the proposed nonlinear model is verified with existing published one. Furthermore, numerical results are presented, which illustrate that nonlinearities exert a significant influence on the dynamic responses of the TLP. 展开更多
关键词 tension leg platform (TLP) finite displacement nonlinear dynamic response numerical solution wave loads
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Feasibility Study on Determining Focal Mechanism Solutions of Small Earthquakes Using the Velocity Amplitude Ratio of -and -Waves
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作者 Zhang Yongjiu Cheng Wanzheng 《Earthquake Research in China》 2008年第3期276-285,共10页
The focal mechanism parameters of small earthquakes are determined by the maximum velocity and displacement amplitude ratio of the direct -and -waves recorded by digital stations. The displacement is obtained from... The focal mechanism parameters of small earthquakes are determined by the maximum velocity and displacement amplitude ratio of the direct -and -waves recorded by digital stations. The displacement is obtained from the velocity by emulation, and the two results are compared and analyzed. Results of theoretical analysis and practical measurement indicate that the two results of velocity and displacement are consistent, and it is feasible that the maximum displacement amplitude ratio be replaced by the maximum velocity amplitude ratio of the direct -and -waves recorded by regional seismic networks when determining focal mechanism solutions of small earthquakes. 展开更多
关键词 地震 参量 周转率 研究
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基于非极限土压力的基坑开挖引起隧道变形的计算方法
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作者 许四法 于均辉 +1 位作者 王哲 郭丙来 《浙江工业大学学报》 CAS 北大核心 2024年第3期312-318,共7页
由于基坑开挖引起邻近隧道变形,继而影响地铁在隧道中的安全运行,因此如何准确预测邻近隧道变形是个值得研究的问题。根据非极限土压力计算方法,计算基坑开挖卸荷坑壁上的土压力,利用Mindlin求解公式,获得基坑开挖阶段旁侧隧道上的附加... 由于基坑开挖引起邻近隧道变形,继而影响地铁在隧道中的安全运行,因此如何准确预测邻近隧道变形是个值得研究的问题。根据非极限土压力计算方法,计算基坑开挖卸荷坑壁上的土压力,利用Mindlin求解公式,获得基坑开挖阶段旁侧隧道上的附加荷载,将隧道结构看作Winkler地基梁上的Euler梁,建立弹性地基梁微分方程,给出隧道水平位移变形的解析方法。基于该方法分析了基坑开挖引起邻近隧道的水平位移。研究结果表明:随着基坑开挖深度的增加,隧道水平位移相应增加;考虑非极限土压力计算得到的隧道水平位移结果与实测值较为接近,误差总体保持在20%以内;相较于传统隧道水平位移求解方法,笔者方法更加符合实际。 展开更多
关键词 基坑开挖 隧道水平位移 非极限土压力 MINDLIN解 弹性地基梁
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串联式锚定板抗拔承载特性及影响因素分析
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作者 刘杰 邹希全 《中南大学学报(自然科学版)》 EI CAS CSCD 北大核心 2024年第4期1537-1550,共14页
为提高锚定板抗拔承载能力,设计串联式锚定板锚固系统。借鉴侧向受荷桩的“M”法,通过锚固系统受力平衡条件及位移连续性条件,提出串联式矩形锚定板锚固系统抗拔力-位移关系的理论分析方法。基于FLAC3D有限差分软件,建立锚定板锚固系统... 为提高锚定板抗拔承载能力,设计串联式锚定板锚固系统。借鉴侧向受荷桩的“M”法,通过锚固系统受力平衡条件及位移连续性条件,提出串联式矩形锚定板锚固系统抗拔力-位移关系的理论分析方法。基于FLAC3D有限差分软件,建立锚定板锚固系统与土相互作用的数值模拟模型,进行埋设于黏性土中不同尺寸的方形锚定板抗拔承载力室内模型试验。结合室内模型试验及数值模拟结果,通过拟合分析,获得串联式矩形锚定板锚固系统抗拔力-位移关系的近似解析解,将3个工程案例中不同尺寸及埋深的锚定板抗拔力-位移的现场试验结果与理论分析及数值模拟结果对比,验证理论分析方法及数值模拟结果的正确性。探讨串联式方形锚定板锚固系统埋深及相邻锚定板间距对锚固系统抗拔承载力的影响。研究结果表明:当锚定板锚固系统埋深H<5b(b为锚定板边长)时,其破坏模式呈现浅埋锚定板的破坏特征;当埋设深度H≥5b时,其破坏模式呈现深埋锚定板破坏特征。对于串联式锚定板锚固系统,为避免相邻锚定板相互影响而降低锚固系统的抗拔承载能力,相邻锚定板间距应满足L≥3b。 展开更多
关键词 串联式锚定板锚固系统 抗拔承载力 抗拔力-位移关系 解析解 数值模拟
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非饱和半空间受埋置集中力作用初值解
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作者 赵云 王超伟 +3 位作者 陈樟龙 张卫民 凌道盛 肖昭然 《土木工程学报》 EI CSCD 北大核心 2024年第5期76-85,共10页
基坑开挖和盾构掘进引起的环境效应是城市岩土工程中的重点,现有研究较少考虑土体的非饱和性。基于连续介质力学建立三维非饱和固结方程,假定初始时段体变为0,孔压和气压不随时间变化,引入McNamee和Schiffman位移函数,将固结方程的初解... 基坑开挖和盾构掘进引起的环境效应是城市岩土工程中的重点,现有研究较少考虑土体的非饱和性。基于连续介质力学建立三维非饱和固结方程,假定初始时段体变为0,孔压和气压不随时间变化,引入McNamee和Schiffman位移函数,将固结方程的初解问题解耦为一组调和方程,通过Hankel变换将偏微分方程组转换为常微分方程组,利用边界条件和连续条件给出变换域内的位移和应力初值解答,最后通过Hankel逆变换给出原非饱和半空间域的解析解答,通过退化算例验证文中方法的正确性。算例分析表明,埋置集中力作用下,随着饱和度减小,位移逐渐减小,超静孔压则呈现先增加后减小的趋势。文中解答可以作为基本解,用于基坑开挖和盾构掘进等工程施工引起的非饱和地层位移场和应力场分析以及对邻近构筑物影响研究。 展开更多
关键词 位移函数法 非饱和半空间 埋置荷载 初值解答
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类矩形盾构隧道开挖引发土体沉降解析解研究
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作者 肖方奇 朱春柏 +3 位作者 甘晓露 俞建霖 龚晓南 刘念武 《铁道标准设计》 北大核心 2024年第3期172-176,191,共6页
类矩形盾构隧道施工可能会导致明显的土体沉降,并进一步影响周围既有建筑物的安全。基于Verruijt解和积分法推导得到类矩形盾构隧道开挖作用下的土体响应解析解,并充分考虑土体等量径向收缩、类矩形隧道竖向、水平向以及旋转位移4个变... 类矩形盾构隧道施工可能会导致明显的土体沉降,并进一步影响周围既有建筑物的安全。基于Verruijt解和积分法推导得到类矩形盾构隧道开挖作用下的土体响应解析解,并充分考虑土体等量径向收缩、类矩形隧道竖向、水平向以及旋转位移4个变形分量的影响,以全面描述复杂施工或地层情况下类矩形盾构开挖引发的土体位移模式。利用实际工程实测数据验证解析解的有效性,并通过参数分析研究各个变形参数对地表土体沉降的影响。研究结果表明,解析理论计算结果与实测数据较为吻合,可较好地评估类矩形盾构引发的土体沉降,类矩形隧道的水平位移和旋转位移会使地表沉降呈现非对称形态,并会使最大地表沉降增大。 展开更多
关键词 类矩形盾构 土体沉降 解析解 体积损失 位移模式
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2023年12月18日甘肃积石山6.2级地震震源机制及其对周围区域的应力影响
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作者 王润妍 万永革 +1 位作者 宋泽尧 关兆萱 《地震》 CSCD 北大核心 2024年第1期175-184,共10页
为研究2023年甘肃积石山6.2级地震对周围地区的应力影响,本文首先根据各个机构和学者提供的震源机制数据确定了本次地震的震源机制中心解。节面Ⅰ:走向159.08°,倾角40.57°,滑动角112.46°;节面Ⅱ:走向310.52°,倾角53... 为研究2023年甘肃积石山6.2级地震对周围地区的应力影响,本文首先根据各个机构和学者提供的震源机制数据确定了本次地震的震源机制中心解。节面Ⅰ:走向159.08°,倾角40.57°,滑动角112.46°;节面Ⅱ:走向310.52°,倾角53.05°,滑动角71.88°。此次地震为逆冲型地震。将当地的应力体系投影到震源机制中心解的两个节面上,得到相对剪应力分别为0.797和0.951,可以看出该地震是区域构造应力场作用下的一次正常能量释放。拉脊山北缘断裂呈NNW走向,SWW倾向,倾角为45°~55°,与震源机制中心解的节面Ⅰ较为一致,判断拉脊山北缘断裂为此次地震发震断裂。基于该地震破裂模型及均匀弹性半空间模型,计算此次地震对周边地区产生的同震位移场及应变场。体应变在震中呈现拉张,距离震中较远的东北和西南两侧呈现轻微拉张,震中周边呈现压缩,东侧压缩表现更为突出。水平位移场表现为在震中西北侧和小部分东南侧的物质向外涌出,而东北侧和西南侧的物质涌入震中;与水平位移场相对应,垂直位移场在震中表现为隆升,而四周表现为略微沉降。 展开更多
关键词 2023年积石山6.2级地震 震源机制中心解 位移场 应变场
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bcc结构下二元合金Fe-X(X=Cr,Co,Mo,W)低温低浓度下固溶软化行为的机制
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作者 王娜 李翔飞 《高等学校化学学报》 SCIE EI CAS CSCD 北大核心 2024年第6期15-21,共7页
采用第一性原理计算研究了体心立方(bcc)Fe的4种二元合金Fe-X(X=Cr,Co,Mo,W)低温低浓度下固溶软化行为的机制,发现低温低浓度下的固溶软化行为由双扭结形核控制,由溶质原子直接引起双扭结形核势垒降低为固溶软化的本征机制,而由溶质原... 采用第一性原理计算研究了体心立方(bcc)Fe的4种二元合金Fe-X(X=Cr,Co,Mo,W)低温低浓度下固溶软化行为的机制,发现低温低浓度下的固溶软化行为由双扭结形核控制,由溶质原子直接引起双扭结形核势垒降低为固溶软化的本征机制,而由溶质原子对间隙原子清除减少双扭结形核为固溶软化的外部机制.分别计算了bcc Fe的4种二元合金Fe-X(X=Cr,Co,Mo,W)中反映双扭结形核势垒的原子行位移(ARD)能和堆垛层错(GSF)能.计算结果表明,仅Cr可微弱降低ARD和GSF能,而Co,Mo,W均引起ARD和GSF能升高,因此,依据固溶软化的本征机制,仅Cr引起固溶软化,而Co,Mo,W均引起固溶强化.Cr,Mo,W与周围Fe原子均为反铁磁相互作用,Co与Fe为铁磁相互作用.尽管铁磁/反铁磁相互作用与价电子数(电子构型)具有一定相关性,双扭结形核势垒并不与价电子数(电子构型)明显相关.进一步的计算表明,双扭结形核势垒与其结合能呈现正相关关系,Cr与Fe结合能减弱,因此双扭结形核势垒降低,而Co,Mo,W与Fe结合能增强,因此双扭结形核势垒升高.而结合能并未表现出与原子半径、电子数(电子构型)的明显相关性,因此,双扭结形核势垒并不与原子半径、电子数(电子构型)明显相关.依据本征机制,Co,Mo,W与Fe的结合能增强引起双扭结形核势垒升高,因此为固溶强化,其二元合金低温低浓度下的固溶软化行为无法用本征机制解释,需要考虑外部机制(如间隙C原子的作用),而Cr二元合金的固溶软化行为可能为本征机制. 展开更多
关键词 体心立方铁 二元合金 原子行位移能 堆垛层错能 固溶软化
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Fractional viscoelastic solution of stratum displacement of a shallow tunnel under the surface slope condition
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作者 Fanchao Kong Dechun Lu +3 位作者 Chao Ma Chenpeng Shen Xiaodong Yang Xiuli Du 《Underground Space》 SCIE EI CSCD 2023年第3期233-247,共15页
The unified displacement function(UDF)is presented to describe the deformation behaviours of the tunnel profile along with time under the surface slope condition.Based on the discrete Fourier method,the third-order UD... The unified displacement function(UDF)is presented to describe the deformation behaviours of the tunnel profile along with time under the surface slope condition.Based on the discrete Fourier method,the third-order UDF in the physical plane is expanded to the Laurent series in the complex variable plane.The complex variable method is employed to derive the elastic analytical solution of stra-tum displacement,when the third-order UDF is taken as the displacement boundary condition of tunnel cross-section(DBCTC).The proposed elastic solution agrees well with the results of the finite element method for the consistent model,which verifies the correctness of the proposed analytical solution.Combining the corresponding principle and fractional Generalized Kelvin viscoelastic constitutive model,the fractional viscoelastic solution under the surface slope condition is determined.The time effect of stratum displacement is presented in two aspects:time-dependent DBCTC and time-dependent material parameters.The parameter analysis is performed to investigate influences of deformation modes of the third-order UDF,slope angle,tunnel radius and fractional order on the time effect of stratum vertical and horizontal displacement. 展开更多
关键词 Third-order unified displacement function Surface slope condition Fractional viscoelastic solution Complex variable method Discrete Fourier method
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丁苯橡胶装置溶剂泵叶轮腐蚀原因分析与对策
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作者 傅蔷 王宇鹏 陈彦军 《全面腐蚀控制》 2024年第6期1-5,82,共6页
本文针对丁苯橡胶装置溶剂泵叶轮的腐蚀,从工艺流程、机泵情况、分析检测数据、理化检验等方面进行分析,并提出解决对策。
关键词 丁苯橡胶 溶剂泵 腐蚀 原因分析 解决措施
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层状异性流变地层桩基长时位移的理论预测
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作者 陈勇 《城市道桥与防洪》 2024年第6期249-253,共5页
针对层状异性流变地层中桩基长时沉降位移预测计算难题,基于荷载传递模式、Poyting-Thomson模型和土体一维虚拟结构等效模型,建立了该类地层中桩基承载模式判别以及桩基服役全过程长时沉降位移的理论预测方法。研究了稳定蠕变地层桩基... 针对层状异性流变地层中桩基长时沉降位移预测计算难题,基于荷载传递模式、Poyting-Thomson模型和土体一维虚拟结构等效模型,建立了该类地层中桩基承载模式判别以及桩基服役全过程长时沉降位移的理论预测方法。研究了稳定蠕变地层桩基承载模式演变及其沉降位移时效特性。结果表明:摩擦承载状态下桩基沉降呈现瞬态弹性;土体的层状异性特型导致桩体压缩变形具有明显的台阶突变;摩擦+桩端共同承载时,桩基总体位移等于桩体形变位移和桩端沉降位移的叠加,具有显著时效特性并随时间逐步趋于稳定。 展开更多
关键词 层状异性地层 稳定蠕变 虚拟柱状结构 桩基位移叠加模型 黏弹性理论解
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