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
This study collected data of the natural disasters which happened during 1900–2015 along the Belt and Road (B & R). Firstly, the main types of disasters were obtained by collation and statistical analysis. Then the development trends of different disasters were analyzed from the time dimension. Finally the spatial distribution patterns of the disaster were analyzed from the spatial dimension. (1) Floods, storms and earthquakes were the most devastating natural disasters in countries along the B & R, among which flood was the most important hazard factor. (2) The year of 1970 is a clear demarcation point. Since 1970, the occurrence of natural disasters gradually increased, and its economic losses soared, but the number of deaths decreased significantly. (3) Southeast Asia and South Asia area were of the highest frequency of disasters. Countries with the largest number of deaths were mainly concentrated in the coastal areas or along the seismic zones. (4) The impacts of disasters were closely related to the economic development of each country. Mongolia’s economy was the most easily affected by disasters. The results of this study can provide references for ascertaining the actual natural disaster situations along the B & R and establishing a comprehensive prevention and mitigation system for disasters.
In order to further study the seismic performance of existing rural buildings in Jiangxi, based on the existing seismic investigation data and preliminary analysis results, taking three typical buildings for example, the elastic-plastic finite element analysis was carried out. For a typical masonry structure damaged in the Jiujiang-Ruichang earthquake in 2005, its seismic damage characteristics were analyzed and its elastic-plastic finite element analysis was carried out, by comparing with actual seismic damage, the validity of the finite element model was verified. Then the seismic performance of rural buildings in early Jiangxi was discussed. On the basis of these, its impacts on the seismic performance of masonry structures were analyzed after adding structural columns and ring beams and increasing the strength of mortar. One typical rural masonry structure and frame structure in Jiangxi were selected respectively to carry out the finite element analysis. Based on the survey data and the prediction results of earthquake damage, the present situation of seismic performance of rural buildings in Jiangxi was reviewed. The results showed that the seismic performance of rural buildings in Jiangxi has improved after the Jiujiang-Ruichang earthquake in 2005, the existing rural buildings investigated in Jiangxi basically met the local seismic fortification requirements. The seismic performance of masonry structure can be improved effectively by adding structural columns and ring beams and increasing the strength of mortar.
In this study, damage ratios of six kinds of high-voltage electrical equipment such as transformers, potential transformers, current transformers, circuit breakers, disconnecting switches and lightning arresters, of 121 substations with 110 kv and above under different seismic intensities in the Wenchuan earthquake were counted. All kinds of high-voltage electrical equipment were assigned damage probability density function curves and damage probability curves in regard to earthquake intensities fitted by normal distribution function and its accumulation function. Based on the curves, their vulnerability curves were then obtained. The statistical results showed that, for all equipment, transformers were the most vulnerable. Followed in order were circuit breaker, lightning arresters, potential transformers, current transformers, and disconnecting switches. Transformers showed some minor damages even in districts of low intensities of 6 and 7, and for higher intensity of 8, their damage probability density reached the peak; while other electrical equipment reached their peak damage probability density for intensities 9 or 9 plus. The damage probability curves of potential transformers, current transformers and disconnecting switches were very close.
The influence of diaphragm wall construction in deep soft soil on adjacent shallow foundation building was studied, and the numerical simulation was used to calculate the long-term settlement of buildings and compared with the measured value. Through the change of the structure internal force caused by uneven settlement of the building, the security of the building was judged. The results showed four points. (1) The settlement of the building was long-term, which is caused by the loss of the soil under the diaphragm wall, the excess pore pressure dissipation, the consolidation of soil and the creep of the soil skeleton. (2) The settlement of the building was mainly the post construction settlement, and the settlement of the building in the construction stage was smaller, which is only 15% of the 455D settlement. The deformation of the soft soil had a great hysteresis. (3) For the settlement of building caused by diaphragm wall in soft soil layer, the HS hardening soil model was adopted in the construction stage, and the SSC creep model was adopted after the work. The simulation result was close to the measured value. (4) The maximum shear stress was mainly concentrated near the larger part of the settlement, and the shear stress of some transverse walls exceeded the shear strength of mortar, so it is necessary to reinforce the corresponding wall.
The infrastructure input-output model was constructed for the first-order and the higher-order to quantitative analyze the effect of interdependence from a macroscopic view. Triangular fuzzy number was introduced to correct the estimated value of experts which would reduce subjective factors. Improved DEMATEL was used to determine the incidence matrix. The combination of each other quantified the association more accurate and effective. The model was applied to the actual case of disaster and make the comparative analysis of interdependence on five critical infrastructures based on the incidence matrix interaction. The model illustrated that the higher-order cyclic interdependence had deeper effects, especially to the system of initial disturbance. So it is useful for protection and effective emergency preparedness of critical infrastructures.
Large horizontal deformation is expected in the base-isolated layer of a base-isolated building when being caught by a rarely-occurred earthquake, which necessitates a flexible connection of pipelines from the foundation to the superstructure to accommodate such large deformation. Although related design codes stipulate the configuration of flexible pipeline connections, the real deformability and seismic performance are lacking in experimental investigation. Three types of seals, namely rubber-based seal, metal-based seal and asbestine-based seal, and two types of connections, i.e., the grab-type joint and ferrule fitting joint, were tested in this study. All specimens were cyclically tested with the pipes filled with pressurized water, either at 1.0 MPa or 2.5 MPa. The water leakage and the mechanical degradation were taken as the failure of specimens. It was observed that the asbestine-based seal leaked at smaller deformations than the other two types of seals. And it was not easy for the ferrule fitting joint to realize the complete boundary of in-filled liquids. Damage states and damage indices of the flexible pipeline were defined based on the test results, together with their seismic fragility curves. Finally, the mechanical model for the flexible pipeline was proposed and the associated parameters were identified from the experimental data. Judged by the forces at specific performance points, the model is able to reproduce the seismic behavior of flexible pipelines accurately, which provides basis of mega model of hospital buildings for seismic performance evaluation.
In order to clarify strength relationship of undisturbed and remolded Bermuda grass roots soil (UBGRS and RBGRS), the root length density, root density and root volume are analyzed to study Bermuda grass roots morphology with laser scanner and root morphology image analysis software, and the strength characteristics of UBGRS and RBGRS are analyzed with laboratory tri-axial tests. Results show that the distribution of Bermuda root most appears on interlaced shape and that a part of root puts on vertical or inclined distribution. Above three root morphology indexes account for the proportion of total root by 93.6%, 85.2%, 93.8%, respectively, in the section of soil mass 0.0–30.0 cm. The cohesion is improved mainly by Bermuda grass roots. The inclined root distribution cannot stably reflect the improvement of soil strength by root. The soil strength increases with confining pressure in every root system distribution, namely, interlaced > vertical > inclined. The incline angle of the roots and per volume of root morphological indexes are the main reasons for the difference of the increase in soil-root complex strength. The ratio of failure strength between RBGRS and UBGRS in interlaced, vertical and inclined distributions is 0.68–1.11, 0.56–0.95, 0.38–0.74 times of that of the undisturbed soil samples, respectively.
In order to investigate the emergency management capability of government and ensure the effective execution of disaster prevention and mitigation, this paper presents a model to evaluate the governmental emergency management capability of meteorological disaster.Through fifteen impact factors of emergency management capability employed and related influences analyzed, the weight factor model is proposed. As the link of the conception of seismic damage index, the classification standard of emergency management capability of meteorological disaster is established. Referring to the average seismic damage index, a conception of average degree of quality is developed. Finally, considering the opinions of experts, a “good” evaluation is given to emergency management capability of meteorological disaster of Shang-cheng district and priority concerned impact factors of promoting evaluation capacity are also suggested.
Urban regional seismic damage prediction provides decision-makers with important information to mitigate and prevent seismic disaster. In order to achieve more reasonable, detailed and intuitive seismic damage prediction of urban buildings, the nonlinear time-history analysis of urban buildings was adopted to perform seismic damage simulation for 230 683 buildings in central Tangshan City. Multi-degree of freedom (MDOF) shear model was used to establish analysis models of low- and mid-rise buildings, and MODF flexural-shear model was adopted for the high-rise buildings. Different stories seismic damage of each building and 3D visualization of buildings’ seismic responses were obtained. The prediction results of three different ground motion attenuation relationships were compared. Then the seismic damage simulation results with the most reasonable ellipsoid attenuation relationship were discussed in detail. The following conclusions can be drawn: (1) The building seismic resistance of Tangshan City has been remarkably improved over the past 40 years; (2) Old un-fortified buildings had very low seismic resistance and should be enhanced by retrofitting as soon as possible. (3) The percentage of buildings in extensive damage or collapsed were very high, resulting in extremely high economy, environment, and resource costs, and hence it is of great importance to improve the seismic “resilience” of cities. The outcomes of this work could provide a useful method and application case for future works on urban seismic damage prediction of buildings.
There are a lot of faults in oil and gas reservoirs in China. The faults can be activated by hydraulic fractures and then lead to earthquakes. In order to study the fault activation mechanism induced by hydraulic fracture, we obtain the tensile and shear activation conditions of fault on the basis of the study of stress state at fracture tip and around the fracture, combining with the pore variation law caused by leak-off. It draws some conclusions by analytical research on the fault activation conditions. The interference of the fracture tip makes fault tension activation when the fracture tip just touches fault and it is divided into two stages. The stress concentration induced fracture tip may lead to the fault failure within a small range in the first stage. The fracturing fluid flows into the small range of fault generated in the first stage, which makes the tension failure of the fault in the second stage. The fracture turns toward fault when both the first stage and the second stage are satisfied. After the fault is crossed by hydraulic fracture, the leak-off of fracturing fluid can make the reservoir pore pressure increase and effective stress decrease with the hydraulic fracturing time accumulation which can make the fault shear slip. The minimum pore pressure makes fault shearing slip go down with the in-situ stress difference increased and the fault dip angle, cohesion, and internal friction angle decreased.
