Study on near-ground wind characteristics of a strong typhoon-wind speed, turbulence intensities, gust factors and peak factors

Huang Peng, Wang Xu and Gu Ming *

In this paper, the wind data are measured from eight anemometers, which were mounted on a 40m tower at the height of 10, 20, 30 and 40 m respectively during typhoon Muifa on the east coast of Shanghai. Mean wind speed and direction, wind speed profiles, turbulence intensities, gust factors and peak factors are analyzed in detail. It is shown that the measured mean wind speed profile agrees well with power law and log law models under 40m height. Turbulence intensities and gust factors calculated from various observation heights first increase with mean wind speed and then almost keep invariant when the wind speed exceeds 10m/s and 12m/s respectively. The longitudinal and lateral gust factors increase with turbulence intensity and the empirical formulas, which can best express their relationship, are also obtained using least-square fitting technique. The profiles of turbulence intensity and gust factors and the variations of gust factors with gust averaging time are presented and related empirical fitting formulas are also obtained. In addition, peak factors for t = 3s are almost constant with the increase of mean wind speed and the averaged values for all 10 min data are 2.21, 2.12 and 2.00 respectively. The relationship between peak factor and gust averaging time on the basis of measured data was consistent with the research result of Durst.

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A fire evacuation model for indoor buildings based on the improved Cellular Automaton

Yang Rui *, Jiang Qinghui and Fang Zheng

Simulation of indoor fire personnel evacuation is of great significance for building design and human security. Based on the theory of Cellular Automata (CA), a new fire evacuation model for indoor buildings is proposed and the corresponding numerical program is developed. Through simulation with a three-room house with a corridor, it is found that the proposed model can effectively simulate personnel evacuation during a fire, demonstrating that it is potentially a powerful tool to find the "bottleneck" in fire evacuation.

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Creation of CO2 Geological Storage Suitability Model in Coal-accumulating Basin based on AHP and Fuzzy Comprehensive Evaluation

Hujun He1,2*, Xingke Yang1, Huixia Chao1 and Wengao Zhang1

Analyzing of effect on greenhouse gas such as CO2 emission to global climate and the significance carrying out research on CO2 underground storage technology system, this study used earth system science theory as a guide, studied index condition of CO2 geological storage suitability in Chinese coal-accumulating basin, fully considered the element of each respect, used analytic hierarchy process and fuzzy comprehensive evaluation, built comprehensive evaluation model of CO2 geological storage suitability in coal-accumulating basin. With Qinshui Basin as an example, the weight of each index was determined using AHP, the result was calculated using the fuzzy comprehensive evaluation, the calculation result coincided with the actual geological survey evaluation. Construction of CO2 geological storage comprehensive evaluation model provides certain reference significance for CO2 geological storage on coal-accumulating basin.

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Revelation from disastrous 6 July 2011 flood and debris flow on a gas well site, Tongjiang County, Southwestern China

Feng Wen-Kai*1, Huang Run-Qiu1 and Lin Ze-Jun2

On 6 July 2011, a disastrous flood and debris flow was triggered by a heavy rainfall in Yanfang gully, Qingyu Town, Tongjiang County, Southwestern China. The debris flow burst following three-hour rainstorm with a maximum intensity of 62.6 mm per hour and an average intensity of 41.73 mm per hour. The gully has two branches divided in the place with elevation of 640m. The upper branch is in V-shape on the whole, with large gully gradient and steep slope. The branch, as the main source zone and catchment zone, has good hydrodynamic condition and large catchment area. The lower branch, gentle and broad, takes on a U-shape on the whole. The branch is the main zone of debris transport and deposit. The source material is mainly derived from transportable gully floor alluvial-pluvial deposits, colluvium and landslide deposits. The volume of the source material is 16.77×104m3 and that of the dynamic volume is 5.17×104m3. The gas well site is just situated in the gully-branch-division area, in the mouth of debris initiation area in the upper gully reach. In the gas well site construction, channel deflection in the gully lowered flood-discharge capacity. That, together with improperly designed overflow bridge, unreasonable site selection and well site lower elevation, resulted in serious gas well site destruction on 6 July disaster. Incision and lateral erosion of the disastrous flood and debris flow produced intense bottom tearing scouring in the gully which caused the slope deposits on the two sides of gully bed to undergo obvious disturbance deformation. That greatly increased debris flow risk happening again in rainy seasons. Thereafter, it can be concluded that debris flow will burst frequently in Yanfang gully in the future.

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Sea Fog by Southerly Warm Air over Cool Sea Waters of the Southward North Korea Cold Current along the Korean East Coast under Cyclogenesis in the Yellow Sea

Choi Hyo

Sea fog in the southeastern coastal sea of Korea was investigated on February 21 ~ 23, 2005 by WRF 3.3 meteorological model, GOES-9 and NOAA-MCSST satellite images. On February 21, as a high pressure covers whole Korean peninsula, northwesterly in the Korean eastern coast caused moderate southwestward wind driven currents, resulting in southward littoral currents due to its coastal configuration. These currents caused further the intrusion of the North Korea Cold Current (NKCC) toward the south. Although air of 3 ~ 70C by cold northwesterly wind from the northern China moved over a cool pool area off the Pohang coast and it was in the easy condition of evaporation of water droplets from the sea and condensation of water vapour to form fogs under the air and sea surface temperature differences of - 3 ~ - 80C, strong marine surface dissipated fog droplet, resulting in 65% relative humidity (RH) with no formation of fog. However, as low pressure showing an anti-clockwise wind pattern on February 22 became more intensified in the Korean northwestern coast (cyclogenesis), southwesterly wind in the Korea northern coastal sea could cause southeastward wind driven currents, which induce upwelling of deep cold waters toward the sea surface and simultaneously these currents caused further the intrusion of the NKCC toward the southea¬stern open sea in about 100km away from Pohang city (a cool pool of 70C cold waters). As much warmer air of 7 ~ 90C by strong southwesterly wind of 6 ~ 11m/s moved over the cool pool in the open sea away from Pohang city, air and sea surface temperature difference was about 20C. So, the air over the cold sea must cool down to be saturated and water vapor in air to be condensed by salty condensation nuclei, resulting in the formation of sea fog or stratus cloud with 80% RH near the sea surface and vertically extended toward 1 km height

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Inclusion of Q-value in parameters used for Earthquake Early Warning Systems

Bhardwaj R*., Sharma M.L. and Kumar A.

A common way to evaluate earthquake parameters for Earthquake Early Warning (EEW) system is to make use of initial portion of the seismic wave ground motion period τc depicting the magnitude (M) of the strong ground motion. τc is in general expressed as the average of initial portion of primary wave (P wave) and approximately represents the width of P wave within the selected window size (generally taking 3 sec after primary wave onset)and is linearly related with magnitude of the earthquake. Since the seismic waves encompass different regions with different properties, these empirical relationships vary region to region. One of the most conspicuous property namely attenuation characteristics is being explored to be included in the regression to look into its effect on the parameters being used for EEW. This study derives regression relation in three parameters τc, M and Qo (quality factor at 1 Hz) considering five different regions of India namely, Garhwal Himalaya, Kumaun Himalaya, Northeast Himalaya, Northwest Himalaya and National capital region. The Indian dataset covering magnitude ranges between 3.3 to 6.8 and an epicentral distance up to 60 km consisting of 66 strong motion records of 33 earthquakes recorded at 49 seismic stations have been considered in the analysis. The regression of τc is found to be logarithmically distributed with a strong variation for different magnitude and Qo values.

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Analytical method for estimating reservoir pressure distribution and fault stability in porous rock during fluid injection

Zhou Junping 1,2, Jiang Yongdong 1,2 and Xian Xuefu 1,2*

It is a well-known fact that an injection of the borehole fluids into surrounding porous rocks often results in fault reactivation (microseismic activity), such as during hydrocarbon production from a reservoir, fluid injection for enhanced oil recovery, hot dry rock geothermal energy extraction and waste disposal or carbon dioxide sequestration. However, no rigorously derived method for the description of spatial and temporal distribution of seismic events and for the estimation of the critical value of pore pressure of a porous rock sufficient for the generation of an microseismic has ever been developed. Model developed within the context of Biot’s theory of poroelasticity is used to obtain the distribution of pore pressure, then the pore pressure is substituted into a Mohr–Coulomb failure criterion to predict the fault stability and the spatio-temporal cluster of microseismic events in a reservoir. In this model, the Biot system of equations is formulated for the radial symmetry case and is supplemented by the relevant boundary conditions, then the solution is constructed analytically.

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An economic loss assessment framework of a region after Wenchuan earthquake

Liu Zhujun and Xu Jiuping

Post-quake economic loss assessment is the foundation of earthquake risk precaution and management measures. It is necessary to propose an effective and efficient assessment framework to assess the economic loss of affected regions. This paper provides an effective and rapid assessment method for regional economic losses after the Wenchuan earthquake which includes both direct and indirect economic loss assessment. The assessment of direct economic loss after Wenchuan earthquake includes building damage loss, property damage and other engineering structure destruction. The indirect economic loss includes loss of enterprise production cessation, industrial related loss and cost of investment premium. The major finding of the paper is that the direct economic loss was the main loss in the Wenchuan earthquake and the industries suffered the most serious damage.

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A new fuzzy risk assessment model of natural disaster based on fuzzy information granulation -exemplified by earthquake disasters

Xue Ye1,2

In this paper, based on fuzzy information granulation approach, a soft hierarchical risk assessment model of natural disasters is developed. The case study is carried out by taking earthquake disasters of Lijiang in Yunnan as an example. The result is compared respectively with the fourth generation of the seismic risk zoning map of China and the soft risk zoning map. The advantages and features of our model are: (1) The data needed in our model are relatively simple or easily available ones which are neither over-complex as in the fourth generation of seismic risk zoning map nor over-simple as the soft risk zoning map; (2) Our model includes both natural and social attributes of the risk assessment of a natural disaster while the merely natural attributes are considered in the fourth generation of seismic risk zoning map and the soft risk zoning map; (3) Our model takes the imprecision of data into account in addition to fuzzy randomness in the involved parameters while the randomness is reflected by means of exceeding probability in the fourth generation of seismic risk zoning map and information diffusion technology is employed to represent fuzzy randomness in the soft risk zoning map. (4) The proposed model presents results in the form of fuzzy information granulation while both the fourth generation of seismic risk zoning map and the soft risk zoning map present an actual value to assess the earthquake risk.

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