Supervisor(s): China Earthquake Asministration Sponsor(s): China Association for Disaster Prevention; Institute of Engineering Mechanics, CEA CN：23-1324/X
Journal of Natural Disasters, started in 1992, publishes papers on disaster prediction and prevention, disaster risk assessment, disaster mitigation for agriculture, meteorology and city, disaster mitigation policy and management system. It also focuses on social factors of natural disasters, loss prediction of earthquake all over the world, awareness improvement on disaster prevention, the system engineering on disaster prevention and mitigation, and so on.
Director XIE Lili
Assistant Director Ou Jinping, Li Youshan, Shi Peijun, Han Linhai, Xiao Yan, Zhou Xianyan, Cui Jie
Editorial Board Ma Zongjin, Ma Zhiliang, Wang Lanmin, Wang Zifa, Wang Chunyi, Wang Zhenqing, Shan Chunchang, Shi Peijun, Fu Qiang, Lv D
The snow disaster has an enormous effect on the safety of people’s life and property. The study of the trend and spatial distribution of the snow disaster in Inner Mongolia can provide a scientific basis for the prevention measures of snow disaster in Inner Mongolia. Using the meteorological data such as the daily temperature and precipitation from 47 meteorological stations in Inner Mongolia from October of every year to March of the next year from 1961 to 2016. In this paper, the changing trend of temperature and the characteristics of spatial and temporal distribution were studied by statistical method, screening method, and ordinary Kriging interpolation method and analyzed the causes of the spatial and temporal distribution of snow disaster. The results show that (1) the number of snow disasters in Inner Mongolia increased from 1961 to 2016, and they were mostly concentrated in October, November, and March. (2) The spatial distribution of snow disasters in Inner Mongolia showed a trend of increasing from west to east. Moderate snow disasters and severe snow disasters were very likely occurred in the eastern part of Inner Mongolia. Snow disasters were concentrated in the low and middle mountain areas in the central and northeastern parts of Inner Mongolia. (3) Inner Mongolia has a vast territory and the east-west span. The spatial and temporal distribution of snow disaster was affected by many factors such as temperature, elevation, latitude, and precipitation.
The natural soft clay generally has a certain structure, which is one of the important internal factors affecting the long-term strength of soft clay. Moreover, the structural properties of soil can reflect its internal pore links and space combination and determine the physical and mechanical effects of soil. For the study on the effect of structural strength on the long-term deformation property of soft clay, creep tests under unconsolidated-undrained conditions were conducted on the artificial soil with the same moisture content but different structural strengths. The results show that the long-term deformation property difference is obvious due to different structural strengths of soft clay. The hydrogeology of soil samples was analyzed and studied, and the empirical formula of long-term strength of soft clay with the effect of structural strength was obtained. Based on the empirical formula proposed in this paper, the structural yield stress (1.9%) was used as the failure criterion of creep deformation in the artificial structural soft clay. The results show that the predicted value is coincident with the test results, and the rationality of the long-term strength prediction formula is verified, which considers the effect of structural strength.
Based on the Doppler radar volume data, meteorological scanning and wind data, the characteristic quantities of downbursts from 2009–2013 in Hubei Province are statistically analyzed, and the nine main radar prewarning indices of downbursts are given by the cloud-model and support vector machine (SVM), which includes the characteristics of environment, radar reflectivity, and radar velocity. On the basis, the downburst prediction models are established by the method of Bayes and BP neural network. The identification results show that the methods can distinguish the downburst and non-downburst, and the probability of detection (POD) of Bayes is 81.8%; the forecast accuracy of downburst and non-downburst is 86.7%; the false alarm rate (FAR) and failure rate (FOM) are 5.2% and 18.1%, respectively. The True skill (TS) score of model is 0.77; the forecast accuracy of downburst based on the nonlinear prediction of BP neural network is 84%, which further proves the predictability and practicability of the downburst prewarning indices.
Combining with the related theory of natural disaster, we established the risk assessment model of drought in Chongqing with the four subsystems of assessment indexes, including the disaster risk, the vulnerability of environment, the exposure of bearing bodies, and the disaster prevention and reduction. Based on the meteorological, ecological, and social economic data of Chongqing, the assessment and regionalization of drought risks in Chongqing were carried out by the GIS spatial data analysis. The results show that (1) the higher-risk regions with various drought-causing factors are located in northwest and northeast of Chongqing which centered on Wuxi, and the lower-risk regions in southeast and northern central parts. (2) The highly-vulnerable areas of drought and disaster-prone environment are mainly located in the northeast of Chengkou, Wuxi, Wushan, and Fengjie as well as the southwest of Qijiang, Nanchuan, Wulong, Fengdu, and Shizhu. Most areas in the west and southeast of Chongqing, including Pengshui, Qianjiang, and Xiushan, are less vulnerable. (3) The exposure of drought-bearing body is lower in most areas of southeasten part, such as Pengshui, Qianjiang, and Xiushan, while higher in northeast, central, and most of southwest parts. (4) Wanzhou and its surrounding are the areas with the highest capacity of disaster prevention and mitigation for drought, and the main urban area and the area around Fuling are the second. The areas with low capacity of disaster prevention and mitigation lie in northeastern and southeastern Chongqing. (5) The risk of different droughts is higher in the northeast, where Wuxi is a high-risk area, and lower in the southeast and the north of Chongqing.
In order to study the cold-wave resistance reliability of municipal buried water supply pipes during cold wave, a structural function of pipes under the influence of temperature change was established. With a water supply pipe in Changzhou as an example, the value of reliability with the temperature change was calculated based on the advanced first order second moment. In addition, the sensitivity analysis of parameters affecting pipe reliability was carried out. Finally, the Monte Carlo method was used to verify the result of this study. The research shows that with the change of temperature during the cold wave, the reliability of the water supply pipeline is also different. We should consider the influence of the cold wave when designing the municipal buried water supply pipes. When the temperature reaches zero during the cold wave, the analysis of cold-wave resistance reliability should consider the frozen stress of the pipe. Under normal operating pressure, the order of parameters affecting pipe reliability is the yield strength of materials, pipe diameter, operating pressure, and wall thickness of pipes, respectively.
At present, the definition of near-fault pulse-type ground motion and far-field harmonic-like ground motion mainly depends on the eye view method, which is defined according to the time-course characteristics. It is subjective and not universal in definition. The standard of reasonable quantification is of great significance for the definition of two types of long-period ground motions. In order to solve this problem, this paper takes the Chi-Chi earthquake long-period ground motion as a sample and proposes a combination of epicenter distance, site category and 90% energy holding-time normalization coefficient
T0.9 of the long-period component energy accumulation spectrum for classification. The method first uses the Hilbert Huang transform to obtain the parameter
T0.9 and then uses this parameter to determine whether the long-period ground motion has a pulse characteristic. According to the analysis of Chi-Chi long-period ground motion, the far and near-field long-period ground motions are distinguished by the difference between the two types of long-period ground motions under different field categories. With the long-period ground motion collected in the Weihe Basin of Wenchuan Earthquake as an example, the proposed classification method is verified.
