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Reliability analysis of excavated slopes in undrained clay

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Frontiers of Structural and Civil Engineering 2023年第11期17卷 1760-1775页

作者： Shuang SHU Bin GE yongxin wu Fei ZHANG Key Laboratory of the Ministry of Education for Geomechanics and Embankment Engineering College of Civil and Transportation EngineeringHohai UniversityNanjing 210098China

A novel approach based on the upper bound theory is proposed to assess the stability of excavated slopes with spatially variable clay in undrained *** proposed random limit analysis is a combination of the deterministic slope stability limit analysis together with random field theory and Monte Carlo simulation.A series of analyses is conducted to verify the potential application of the proposed method and to investigate the effects of the soil undrained shear strength gradient and the spatial correlation length on slope *** groups of potential sliding surfaces are identified and the occurrence probability of each sort of failure mechanism is quantified for various slope *** proposed method is found to be feasible for evaluating slope *** obtained results are helpful in understanding the slope failure mechanism from a quantitative point of *** paper could provide guidance for slope targeted local reinforcement.

关键词： slope stability spatial variability limit analysis random field clay

A note on near-field site amplification effects of ground motion from a radially inhomogeneous valley

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Earthquake Engineering and Engineering Vibration 2018年第4期17卷 707-718页

作者： Zhang Ning Gao Yufeng wu yongxin Zhang Fei Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering Hohai University College of Civil and Transportation Engineering Hohai University

To improve the understanding of the near-field soil and topographic amplification effects, an analytical solution by the authors for the scattering of plane SH waves by a radially inhomogeneous semi-cylindrical valley is extended to the case of a line source of cylindrical SH waves. Upon confirmation of its accuracy with past exact solutions for a homogeneous and an inhomogeneous semi-cylindrical valley under far-field plane SH waves, the extended solution is used to calculate the ground motion amplification factors for both the homogeneous and inhomogeneous valleys subjected to near-field waves. A comprehensive parametric study is conducted with respect to the location of the wave source, the dimensionless frequency of the incident waves, and the inhomogeneity degree of the covering soil layer. It is found that more amplifications and reductions of ground motions will occur within a certain range in and around the valley as the sources are located further. Consistent with the far-field case, it is confirmed that an increase of the degree of inhomogeneity of the covering soil layer generally amplifies the ground motions significantly.

关键词： elastic SH-waves wave scattering and diffraction ground motion amplification valley canyon

Effects of vertical seismic acceleration on 3D slope stability

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Earthquake Engineering and Engineering Vibration 2016年第3期15卷 487-494页

作者： Zhang Fei Gao Yufeng wu yongxin Zhang Ning Qiu Yue Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering Hohai University

The conventional pseudo-static approach often neglects the effect of the vertical＇ seismic acceleration on the stability of a slope, but some analyses under plane-strain （2D） conditions show a significant effect on the slope stability. The purpose of this study is to investigate the effect of the vertical acceleration on the safety of three-dimensional （3D） slopes. In the strict framework of limit analysis, a 3D kinematically admissible rotational failure mechanism is adopted here for 3D homogeneous slopes in frictional/cohesive soils. A set of stability charts is presented in a wide range of parameters for 3D slopes under combined horizontal and vertical seismic loading conditions. Accounting for the effects of the vertical seismic acceleration, the difference in safety factors for 3D slopes can exceed 10%, which will significantly overestimate the safety of the 3D slopes.

关键词： slope stability seismic effects limit states three-dimensional analysis vertical acceleration

Approximation approach to the SRM based on root decomposition in the simulation of spatially varying ground motions

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Earthquake Engineering and Engineering Vibration 2013年第3期12卷 363-372页

作者： wu yongxin Gao Yufeng Li Dayong Xu Changjie Ali H Mahfouz Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering Hohai University Institute of Engineering Safety and Disaster Prevention Hohai University Geotechnical Research Institute Hohai University Department of Civil Engineering Shandong University of Science and Technology Research Center of Coastal and Urban Geotechnical Engineering Zhejiang University College of Engineering Jazan University

The spectral representation method （SRM） is widely used to simulate spatially varying ground motions. This study focuses on the approximation approach to the SRM based on root decomposition, which can improve the efficiency of the simulation. The accuracy of the approximation approach may be affected by three factors： matrix for decomposition, distribution of frequency interpolation nodes and elements for interpolation. The influence of these factors on the accuracy of this approach is examined and the following conclusions are drawn. The SRM based on the root decomposition of the lagged coherency matrix exhibits greater accuracy than the SRM based on the root decomposition of the cross spectral matrix. The equal energy distribution of frequency interpolation nodes proposed in this study is more effective than the counter pith with an equal spacing. Elements for interpolation do not have much of an effect on the accuracy, so interpolation of the elements of the decomposed matrix is recommended because it is less complicated from a computational efficiency perspective.

关键词： ground motions simulation spectral representation method spatially varying approximation root decomposition

An efficient probabilistic design approach for tunnel face stability by inverse reliability analysis

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Geoscience Frontiers 2021年第5期12卷 374-383页

作者： Jian Ji Zheming Zhang Zhijun wu Jiacheng Xia yongxin wu Qing Lüc Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering Hohai UniversityNanjingChina School of Civil Engineering Wuhan UniversityWuhanChina c College of Civil EngineeringZhejiang UniversityHangzhouChina

In order to maintain the safety of underground constructions that significantly involve geo-material uncertainties,this paper delivers a new computation framework for conducting reliability-based design(RBD)of shallow tunnel face stability,utilizing a simplified inverse first-order reliability method(FORM).The limit state functions defining tunnel face stability are established for both collapse and blow-out modes of the tunnel face failure,respectively,and the deterministic results of the tunnel face support pressure are obtained through three-dimensional finite element limit analysis(FELA).Because the inverse reliability method can directly capture the design support pressure according to prescribed target reliability index,the computational cost for probabilistic design of tunnel face stability is greatly *** comparison with Monte Carlo simulation results,the accuracy and feasibility of the proposed method are ***,this study presents a series of reliability-based design charts for vividly understanding the limit support pressure on tunnel face in both cohesionless(sandy)soil and cohesive soil stratums,and their optimal support pressure ranges are *** results show that in the case of sandy soil stratum,the blowout failure of tunnel face is extremely unlikely,whereas the collapse is the only possible failure *** parametric study of various geotechnical uncertainties also reveals that ignoring the potential correlation between soil shear strength parameters will lead to over-designed support pressure,and the coefficient of variation of internal friction angle has a greater influence on the tunnel face failure probability than that of the cohesion.

关键词： Tunnel face stability Support pressure Finite element limit analysis Inverse reliability analysis Probabilistic design

Study of the approximate approaches to the POD based spectral representation method

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Science China(Technological Sciences) 2013年第4期56卷 970-979页

作者： wu yongxin GAO YuFeng LI DaYong XU ChangJie MAHFOUZ Ali Hasson Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering Hohai University Institute of Engineering Safety and Disaster Prevention Hohai University Geotechnical Research Institute Hohai University Department of Civil Engineering Shandong University of Science and Technology Research Center of Coastal and Urban Geotechnical Engineering Zhejiang University College of Engineering Jazan UniversityJazanSaudi Arabia

The spectral representation method (SRM) is most widely used in simulating the stochastic *** proper orthogonal decomposition (POD) based SRM is an important *** paper investigates the approximate approaches to the POD-based SRM in simulating two typical problems,i.e.,the seismic ground motion and wind velocity fields ***,the accuracy resulting from the power spectral density matrix-based POD method (PSRM) is compared to that of the coherency matrix-based POD method (CPSRM).It is concluded that the CPSRM maintains a much higher accuracy than the *** the CPSRM,the linear interpolation of eigenvectors and third-order polynomial interpolation of eigenvalues can be accepted to attain high accuracy;the linearly distributed interpolation nodes are effective in the ground motions simulation;however,the exponentially distributed interpolation nodes are effective in the wind velocity simulation.

关键词： stochastic field simulation coherency matrix based spectral representation method proper orthogonal decomposition approximation

A hybrid artificial bee colony algorithm and support vector machine for predicting blast-induced ground vibration

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Earthquake Engineering and Engineering Vibration 2022年第4期21卷 861-876页

作者： Zhu Chun Xu Yingze wu yongxin He Manchao Zhu Chuanqi Meng Qingxiang Lin Yun School of Earth Sciences and Engineering Hohai UniversityNanjing 210098China State Key Laboratory for Geomechanics&Deep Underground Engineering China University of Mining andTechnology(Beijing)Beijing 100083China State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines AnhuiUniversity of Science and TechnologyHuainan 232001China College of Petroleum Engineering Xi’an Shiyou UniversityXi’an 710065China School of Resources and Safety Engineering Central South UniversityChangsha 410083China

Because nearby construction has harmful effects,precisely predicting blast-induced ground vibration is *** this paper,a hybrid artificial bee colony(ABC)and support vector machine(SVM)model was proposed for predicting the value of peak particle velocity(PPV),which is used to describe blast-induced ground *** construct the model,5 potentially relevant factors,including controllable and uncontrollable parameters,were considered as input parameters,and PPV was set as the output ***-five samples were recorded from the Hongling lead-zinc *** ABC-SVM model was developed and trained on 35 samples via 5-fold cross-validation(CV).A testing set(10 samples)was used to evaluate the prediction performance of the ABC-SVM *** and four empirical models(United States Bureau of Mines(USBM),Amraseys-Hendron(A-H),Langefors-Kihstrom(L-K),and Central Mining Research Institute(CMRI))also were introduced for ***,the performances of the models were analyzed by using 3 statistical parameters:the correlation coefficient(R2),root-mean-square error(RMSE),and variance accounted for(VAF).ABC-SVM had the highest R2 and VAF values followed by the SVM,A-H,USBM,CMRI,and L-K *** results demonstrated that ABC-SVM outperformed SVM and the empirical predictors for predicting ***,the best results from the R2,RMSE,and VAF indices were 0.9628,0.2737,and 96.05%for the ABC-SVM *** sensitivities of the parameters also were investigated,and the height difference between the blast point and the monitoring station was found to be the parameter that had the most influence on PPV.

关键词： recycled concrete frame-shear wall concealed bracings shaking table test nonlinear time-history response analysis

Scattering of SH waves induced by a symmetrical V-shaped canyon: a unified analytical solution

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Earthquake Engineering and Engineering Vibration 2012年第4期11卷 445-460页

作者： Zhang Ning Gao Yufeng Li Dayong wu yongxin Zhang Fei Geotechnical Research Institute Hohai University Key Laboratory of Geomechanics and Embankment Engineering(Hohai University) Ministry of Education College of Civil Engineering&Architecture Shandong University of Science and Technology

This paper reports a series solution of wave functions for two-dimensional scattering and diffraction of plane SH waves induced by a symmetrical V-shaped canyon with different shape ratios. A half-space with a symmetrical V-shaped canyon is divided into two sub-regions by using a circular-arc auxiliary boundary. The two sub-regions are represented by global and local cylindrical coordinate systems, respectively. In each coordinate system, the wave field satisfying the Helmholtz equation is represented by the separation of variables method, in terms of the series of both Bessel functions and Hankel functions with unknown complex coefficients. Then, the two wave fields are described in the local coordinate system using the Graf addition theorem. Finally, the unknown coefficients are sought by satisfying the continuity conditions of the auxiliary boundary. To consider the phase characteristics of the wave scattering, a parametric analysis is carried out in the time domain by assuming an incident signal of the Ricker type. Surface and subsurface transient responses demonstrate the characteristics and mechanisms of wave propagating and scattering.

关键词： SH-wave scattering V-shaped canyon topographic effect wave propagation earthquake ground motion wave function expansion method

NiSiO2太阳光谱选择吸收涂层的设计制备及热稳定性研究

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功能材料 2018年第9期49卷 9101-9106页

作者：武永鑫王聪中国大唐集团科学技术研究院有限公司北京100040 北京航空航天大学物理学院凝聚态物理与材料物理研究中心北京100191

采用软件模拟辅助实验的方式制备了新型Al/NiSiO_2(M)/NiSiO_2(D)/SiO_2太阳光谱选择吸收涂层,并对其热稳定性进行了研究。使用磁控溅射技术,通过改变氧气(O_2)流量制备了一系列NiSiO_2膜层,研究了O_2流量对膜层光学性能的影响,并使用... 详细信息

采用软件模拟辅助实验的方式制备了新型Al/NiSiO_2(M)/NiSiO_2(D)/SiO_2太阳光谱选择吸收涂层,并对其热稳定性进行了研究。使用磁控溅射技术,通过改变氧气(O_2)流量制备了一系列NiSiO_2膜层,研究了O_2流量对膜层光学性能的影响,并使用光学模拟软件对涂层进行设计和优化。根据模拟优化结果在不锈钢基底上成功制备了Al/NiSiO_2(M)/NiSiO_2(D)/SiO_2光谱选择吸收涂层,其吸收率(α)为0.933,400℃下的发射率(ε)为0.14。涂层在空气中450℃高温下热处理100h后,其吸收率与发射率之比(α/ε)由6.66上升至7.62,依然保持着较高的光谱选择性,表明涂层具有较好的热稳定性。

关键词：光谱选择吸收涂层介电函数模型磁控溅射光学模拟