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ground state solutions for a class of fractional Kirchhoff equations with critical growth

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Science China Mathematics 2019年第5期62卷 853-890页

作者： Xiaoming He Wenming Zou College of Science Minzu University of China Department of Mathematical Sciences Tsinghua University

In this paper, we study the effect of lower order perturbations in the existence of positive solutions to the fractional Kirchhoff equation with critical growth■ where a, b > 0 are constants, μ > 0 is a parameter,■ , and V : R^3→ R is a continuous potential function. For suitable assumptions on V, we show the existence of a positive ground state solution, by using the methods of the Pohozaev-Nehari manifold, Jeanjean's monotonicity trick and the concentration-compactness principle due to Lions(1984).

关键词： fractional Kirchhoff equations ground state solutions Pohozaev-Nehari manifold critical Sobolev exponent

ground support design for dynamic loading conditions:A quantitative data-driven approach based on rockburst case studies

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Journal of Rock Mechanics and Geotechnical Engineering 2019年第5期11卷 909-919页

作者： Philippe Morissette John Hadjigeorgiou Agnico Eagle Mines Limited 10 200route de PreissacRouyn-NorandaJ0Y 1C0Canada University of Toronto TorontoM5S 3E3Canada

There are considerable challenges associated with the design of ground support for seismically-active underground *** is extremely difficult to establish the demand on ground support as well as the capacity of a ground support *** resulting dynamic or impact loads caused by mining-induced seismicity are difficult to anticipate and *** performance of a ground support system is defined by the load distribution and interaction between several reinforcement and surface support ***,the design of ground support in seismically-active mines tends to evolve,or be modified based on qualitative assessments of perceived performance or response to significant seismic events or *** research is motivated by a need to provide quantitative and data-driven design guidelines for ground support systems subjected to dynamic-loading *** data were collected from three deep and seismically-active underground mines in the Sudbury basin in *** constructed database comprises 209 seismic events that resulted in damage to mine excavations and ground *** events were associated with damage at 324 locations within the three *** developed ground support design strategy,based on these documented case studies,identifies areas where the use of dynamic or enhanced support should be *** developed design methodology provides guidelines for the zoning of mine locations in which installation of enhanced support is recommended,the specifications for an optimal ground support system,and the timing or sequence of installation.

关键词： ground support design Mining-induced seismicity Rockburst

ground behaviour analysis,support system design and construction strategies in deep hard rock mining-Justified in Western Australian’s mines

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第1期12卷 1-20页

作者： Behrooz Rahimi Mostafa Sharifzadeh Xia-Ting Feng Department of Mining and Metallurgical Engineering Western Australian School of Mines:MineralsEnergy and Chemical Engineering(WASM-MECE)Curtin UniversityKalgoorlieWM6430Australia Key Laboratory of Ministry of Education for Safe Mining of Deep Metal Mines Northeastern UniversityShenyang110819China

Development of deep underground mining projects is crucial for optimum extraction of mineral *** main challenges at great depth are high rock stress levels,seismic events,large-scale deformation,sudden failures and high temperatures that may cause abrupt and unpredictable instability and collapse over a large *** this paper,a ground control and management strategy was presented corresponding to the three stages of projects:strategic design,tactical design and operational *** design is results in preparing a broad plan and primary design for mining *** tactical design is to provide detail design such as stabilisation *** design stage is related to monitoring and updating design *** most effective ground control strategies in this stage are maintenance,rehabilitation,monitoring and contingency ***,a new procedure for design of ground support systems for deep and hard rock was *** main principles are:static and/or dynamic loading types,determination of loading sources,characterisation of geological conditions and the effects of orientation of major structures with openings,estimation of ground loading factor,identification of potential primary and secondary failures,utilisation of appropriate design analysis methods,estimation of depth failure,calculation of the static and/or dynamic demand ground support capacity,and selection of surface and reinforcement *** force is the dominant loading force in low-level *** high stress level failure mechanism becomes more complex in rock mass *** this condition,a variety of factors such as release of stored energy due to seismic events,stress concentration,and major structures influence on ground behaviour and judgement are very *** key rock engineering schemes to minimise the risk of failures in high-stress levels at great depth involve depressurisation and quality control of ***

关键词： ground management Support system design Sequential excavation Stress management Geotechnical monitoring Deep underground mines

Rotational motions of the Ms7.0 Jiuzhaigou earthquake with ground tilt data

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Science China Earth Sciences 2019年第5期62卷 832-842页

作者： Cong ZHOU Xiangzhi ZENG Qingliang WANG Wenyi LIU Cuizhi WANG The Second Monitoring and Application Center China Earthquake Administration Institute of Geology China Earthquake Administration Institute of Geology Chinese Academy of Geological Sciences

Observation and research of rotational motions induced by earthquake has been ignored in the past decades due to the lack of understanding of important ground rotational motions and practical difficulty involved in directly measuring the rotational components. Currently, there is a paucity of methods to directly measure rotational motions in China. The present study attempts to discuss the possibility of obtaining seismic rotation from ground tilt data. The rotational motions generated by shear dislocation source are derived based on the displacement formula of elastic wavefields in the homogenous space. The characteristics of the three components of translational and rotational motions in near, intermediate, and far fields are compared and analyzed. Based on the corresponding relationship between the rotation and ground tilt on free surface boundary, a method to indirectly construct the rotational motions in the layered half space is obtained. Finally, the theoretical rotational motions generated by the Ms7.0 earthquake in Jiuzhaigou, Sichuan Province, on August 8, 2017 are calculated. The results indicate that the rotational motions generated by the Jiuzhaigou earthquake are concentrated in the vicinity of the epicenter(approximately150 km) and mainly distributed in the area perpendicular to the fault strike. The existence of free surface boundary attenuates the total energy of the rotational field and especially in the direction of the dominant energy. The ground tilt data is compared with rotational motions in the layered half space, and the results indicate that theoretical rotations and actual ground tilt data are essentially consistent, especially in the far field region. Thus, it is possible to obtain horizontal components of rotation from ground tilt data, and this provides more information for a complete description of the motion characteristics of an underground medium.

关键词： Rotational motions Layered half space Jiuzhaigou earthquake ground tilt Strike slip fault

Intensity measures for the seismic response evaluation of buried steel pipelines under near-field pulse-like ground motions

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Earthquake Engineering and Engineering Vibration 2019年第4期18卷 917-931页

作者： Alireza Kiani Mehdi Torabi S.Mohammad Mirhosseini Department of Civil Engineering Islamic Azad University Arak Branch Arak 12346 Iran Department of Civil Engineering Islamic Azad University Kangan Branch Kangan 12345 Iran Department of Civil Engineering Islamic Azad University Arak Branch Arak 34125 Iran

ground-motion Intensity Measures (IMs) are used to quantify the strength of ground motions and evaluate the response of structures. IMs act as a link between seismic demand and seismic hazard analysis and therefore, have a key role in performance-based earthquake engineering. Many studies have been carried out on the determination of suitable IMs in terms of effi ciency, suffi ciency and scaling robustness. The majority of these investigations focused on ordinary structures such as buildings and bridges, and only a few were about buried pipelines. In the current study, the optimal IMs for predicting the seismic demand of continuous buried steel pipelines under near-fi eld pulse-like ground motion records is investigated. Incremental dynamic analysis is performed using twenty ground motion records. Using the results of the regression analysis, the optimality of 23 potential IMs are studied. It is concluded that specifi c energy density (SED) followed by VSI[ω1(PGD+RMSd )] are the optimal IMs based on effi ciency, suffi ciency and scaling robustness for seismic response evaluation of buried pipelines under near-fi eld ground motions.

关键词： continuous buried steel pipeline intensity measure scaling robustness pulse-like ground motion records performance-based earthquake engineering

Stochastic earthquake source model for ground motion simulation

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Earthquake Engineering and Engineering Vibration 2019年第1期18卷 1-34页

作者： P.R.Lekshmy S.T.G.Raghukanth Department of Civil Engineering

In the analysis and design of important structures with relatively long life spans, there is a need to generate strong motion data for possible large events. The source of an earthquake is characterized by the spatial distribution of slip on the fault plane. For future events, this is unknown. In this paper, a stochastic earthquake source model is developed to address this issue. Here, 1D and 2D stochastic models for slip distribution developed by Lavallée et al.(2006) are used. The random field associated with the slip distribution is heavy-tailed stable distribution which can be used for large events. Using 236 past rupture models, the spectral scaling parameter and the four stable or Levy's parameters against empirical relationship for known quantities like magnitude or fault length are developed. The model is validated with data from 411 stations of 1999 Chi-Chi earthquake. The simulated response spectrum showed good agreement to actual data. Further the proposed model is used to generate ground motion for the 1993 Killari Earthquake where strong motion data is not available. The simulated mean peak ground velocity was in turn related to the intensity(MSK) and compared against values in the literature.

关键词： stochastic slip distribution ground motion Levy’s parameters Killari earthquake

Experimental investigation of railway train-induced vibrations of surrounding ground and a nearby multi-story building

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Earthquake Engineering and Engineering Vibration 2009年第1期8卷 137-148页

作者： Xia He Chen Jianguo Wei Pengbo Xia Chaoyi G. De Roeck G. Degrande School of Civil Engineering Beijing Jiaotong University Beijing 100044 China Department of Civil Engineering Catholic University of Leuven B-3001 Heverlee Belgium

In this paper, a field experiment was carried out to study train-induced environmental vibrations. During the field experiment, velocity responses were measured at different locations of a six-story masonry structure near the Beijing- Guangzhou Railway and along a small road adjacent to the building. The results show that the velocity response levels of the environmental ground and the building floors increase with train speed, and attenuate with the distance to the railway track. Heavier freight trains induce greater vibrations than lighter passenger trains. In the multi-story building, the lateral velocity levels increase monotonically with floor elevation, while the vertical ones increase with floor elevation in a fluctuating manner. The indoor floor vibrations are much lower than the outdoor ground vibrations. The lateral vibration of the building along the direction of weak structural stiffness is greater than along the direction with stronger stiffness. A larger room produces greater floor vibrations than the staircase at the same elevation, and the vibration at the center of a room is greater than at its corner. The vibrations of the building were compared with the Federal Transportation Railroad Administration （FTA） criteria for acceptable ground-borne vibrations expressed in terms ofrms velocity levels in decibels. The results show that the train-induced building vibrations are serious, and some exceed the allowance given in relevant criterion.

关键词： train building ground environmental vibration field experiment

Rating damage potential of ground motion records

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Earthquake Engineering and Engineering Vibration 2019年第2期18卷 233-254页

作者： Bhargavi Podili Raghukanth S.T.G Department of Civil Engineering Indian Institute of Technology Madras

In this study, a total of 115,246 ground motions recorded during earthquakes of Moment magnitudes ranging from M_w 5.0 to M_w 9.0 are analyzed statistically. A total of 21 ground motion parameters characterising the recorded acceleration time histories are used in the analysis. Classification of these parameters through statistical correlation is reported and a parameter called "distance from zero-amplitude axis," or d_(Z-A), is formulated in the principal component space. The ability for d_(Z-A) to rate the damage potentials of strong motion records is evaluated through correlation of d_(Z-A) with Japan Meteorological Agency(JMA) instrumental seismic intensities. This parameter can be used to rate damage potential of any strong motion record irrespective of the magnitude and location of the earthquake. It can also be used in selecting ground motion records of appropriate damage potential in seismic design and probabilistic analysis.

关键词： damage potential principal component analysis ground motion parameters zero-amplitude axis

Considerations for effective ground support in evaporites

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International Journal of Mining Science and Technology 2019年第1期29卷 113-118页

作者： J.R.Nopola C.A.Vining RESPEC

Evaporites, such as salt and potash, pose unique problems to ground-support designs that are not encountered in other rock types. Evaporites are subject to continual creep and no amount of ground support can successfully arrest this process. Common ground-support techniques that are useful for most rock types may reduce the effective life of bolts in evaporite mines and create unseen hazards. A different approach to ground support must be applied to provide long-term support in areas where high creep rates are present. The goal of effective ground-support designs in these situations is not to contain and prevent the rock from moving; rather, the ground-support design must be able to move along with the rock and contain any fully detached slabs until additional remediation measures can be *** most appropriate ground-support designs will consider the expected movement of the rock and the duration that the area needs to remain accessible.

关键词： ground support ground control Rock mechanics And salt mechanics