排序方式： 共有11条查询结果，搜索用时 93 毫秒
1.
Nazli Yonca Aydin H. Sebnem Duzgun Friedemann Wenzel Hans Rudolf Heinimann 《Natural Hazards》2018,91(1):37-68
Transportation networks daily provide accessibility and crucial services to societies. However, they must also maintain an acceptable level of service to critical infrastructures in the case of disruptions, especially during natural disasters. We have developed a method for assessing the resilience of transportation network topology when exposed to environmental hazards. This approach integrates graph theory with stress testing methodology and involves five basic steps: (1) establishment of a scenario set that covers a range of seismic damage potential in the network, (2) assessment of resilience using various graph-based metrics, (3) topology-based simulations, (4) evaluation of changes in graph-based metrics, and (5) examination of resilience in terms of spatial distribution of critical nodes and the entire network topology. Our case study was from the city of Kathmandu in Nepal, where the earthquake on April 25, 2015, followed by a major aftershock on May 12, 2015, led to numerous casualties and caused significant damage. Therefore, it is a good example for demonstrating and validating the developed methodology. The results presented here indicate that the proposed approach is quite efficient and accurate in assisting stakeholders when evaluating the resilience of transportation networks based on their topology. 相似文献
2.
Kazan Trona ore field, the second discovered deposit in Central Turkey, is planned to be extracted by solution mining technology. Understanding the hydrogeology of the springs in such an area is vital since they can be affected during mining operations. The aim of this study is to provide an isotopic approach by utilizing environmental isotope techniques to the springs in the study area, thereby, to enhance the understanding of their occurrence by complementing the previous geochemical studies. Here, the isotopic signatures and the recharge elevations of the springs are demonstrated together with their field parameters. The relationship between ??D and ??18O suggest strong evaporation in some of the samples after recharge. For those springs, the unmodified signatures were determined and the recharge elevations were calculated to be between 1100 and 1248 m. These elevations correspond to Incirlik and Asmalidere Members and upper Neogene units. The relationship between Tritium and Electrical Conductivity suggested that SP-6, SP-3 and SP-4 have shallow circulation when compared to SP-7 having both the lowest tritium and highest EC value. This finding is in accordance with the geochemical data, which suggests SP-7 emerges from the deeper, older groundwater present above the trona deposit. 相似文献
3.
A Methodology for Reliability-Based Design of Rock Slopes 总被引：10，自引：0，他引：10
Summary A reliability-based methodology for the design of rock slopes, that can easily be implemented by the practicing engineers
is proposed. The advanced first-order second-moment (AFOSM) method is adopted as the reliability assessment model and its
application is illustrated for the case of plane failure. A model is developed within the framework of first-order second-moment
approach to analyze the uncertainties underlying the in situ shear strength properties of rock discontinuities. Here, particular
emphasis is given on the assessment of uncertainties related to the shear characteristics of clean, unfilled rock discontinuities
under low normal stress levels. An extensive literature survey on the shear characteristics of discontinuities is carried
out in order to collect data for the quantification of uncertainties. The data extracted from this literature survey are classified
and reprocessed so that they can be utilized in the uncertainty analysis model. A user friendly software called ROCKREL is
developed to carry out the numerical computations and to make the proposed design format more practical.
Received April 16, 2001; accepted June 10, 2002; Published online November 19, 2002
Authors' address: Prof. Celal Karpuz, Middle East Technical University, Faculty of Engineering, Department of Mining Engineering, 06531 Ankara,
Turkey; e-mail: karpuz @metu.edu.tr 相似文献
4.
5.
H. S. B. Duzgun M. S. Yucemen H. S. Kalaycioglu K. Celik S. Kemec K. Ertugay A. Deniz 《Natural Hazards》2011,59(2):917-947
In this paper, an integrated urban earthquake vulnerability assessment framework, which considers vulnerability of urban environment
in a holistic manner and performs the vulnerability assessment for the neighborhood scale, is proposed. The main motivation
behind this approach is the inability to implement existing vulnerability assessment methodologies for countries like Turkey,
where the required data are usually missing or inadequate for the decision-makers in prioritization their limited resources
for risk reduction in the administrative units from which they are responsible for. The methodology integrates socio-economical,
structural, coastal, ground condition, vulnerabilities (fragilities), as well as accessibility to critical services. The proposed
methodology is implemented for Eskisehir, which is one of the metropolitans of Turkey. In the implementation of the proposed
framework, geographic information system (GIS) is used. While the overall vulnerabilities obtained for neighborhoods are mapped
in GIS, the overall vulnerabilities obtained for buildings are visualized in 3D city model. The main reason behind using different
mapping and visualization tools for vulnerabilities is to provide better ways for communicating with decision-makers. The
implementation of the proposed vulnerability assessment methodology indicates that an urban area may have different vulnerability
patterns in terms of structural, socio-economical, and accessibility to critical services. When such patterns are investigated,
effective vulnerability reduction policies can be designed by the decision-makers. The proposed methodology well serves for
this purpose. 相似文献
6.
Probabilistic analyses provide rational means to treat the uncertainties associated with underlying parameters in a systematic
manner. The stability of a 734-m-high jointed rock slope in the west of Norway, the Oppstadhornet rock slope, is investigated
by using a probabilistic method. The first-order reliability method (FORM) is used for probabilistic modeling of the plane
failure problem in the rock slope. The Barton–Bandis (BB) shear strength criterion is used for the limit state equation. The
statistical distributions of the BB criterion parameters, for which comprehensive data were collected and statistically analyzed,
are determined by using distribution fitting algorithms. The sensitivity of the FORM model for the BB criterion is also investigated.
It is found that the model is most sensitive to the mean value of the residual friction angle (ϕ
r) and least sensitive to the mean value of the slope angle (β
f). It is also found that the standard deviation of joint compressive strength (JCS) causes the greatest difference in the
reliability index, which has the least sensitivity to the change in the mean and standard deviation of joint roughness coefficient
(JRC). 相似文献
7.
8.
Kivanc Ertugay Sebnem Duzgun 《International journal of geographical information science》2013,27(9):1491-1506
The term physical accessibility has long been used by geographers, economists, and urban planners and reflects the relative ease of access to/from several urban/rural services by considering the traveling costs. Numerous accessibility measures, ranging from simple to sophisticated, can be observed in the geographical information systems (GIS)-based accessibility modeling literature. However, these measures are generally calculated from a constant catchment boundary (a most likely or average catchment boundary) based on constant deterministic transportation costs. This is one of the fundamental shortcomings of the current GIS-based accessibility modeling and creates uncertainty about the accuracy and reliability of the accessibility measures, especially when highly variable speeds in road segments are considered. The development of a new stochastic approach by using global positioning system (GPS)-based floating car data and Monte Carlo simulation (MCS) technique could enable handling the variations in transportation costs in a probabilistic manner and help to consider all possible catchment boundaries, instead of one average catchment boundary, in accessibility modeling process. Therefore, this article proposes a stochastic methodology for GIS-based accessibility modeling by using GPS-based floating car data and MCS technique. The proposed methodology is illustrated with a case study on medical emergency service accessibility in Eskisehir, Turkey. Moreover, deterministic and stochastic accessibility models are compared to demonstrate the differences between the models. The proposed model could provide better decision support for the decision-makers who are supposed to deal with accessibility, location/allocation, and service/catchment area related issues. 相似文献
9.
10.