城市化过程中房屋地震灾害脆弱性和损失风险变化研究——以唐山市区及城乡过渡乡镇为例

STUDY ON THE CHANGES OF VULNERABILITY AND LOSS RISK OF BUILDINGS FROM SEISMIC DISASTER IN THE PROCESS OF URBANIZATION —A CASE STUDY OF TANGSHAN AREA

以1976年、1995年、2002年和2009年为代表时期,利用前期研究给出的基于高分辨率遥感的群体房屋地震灾害脆弱性和震灾损失风险分析方法,分析了唐山市区及城乡过渡乡镇群体房屋地震灾害脆弱性和震灾损失风险近30多年来的整体变化。结果表明:1976—2009年,研究区房屋暴露量显著增加、结构脆弱性逐渐降低;在设定遭受Ⅵ～Ⅺ度地震烈度条件下,房屋破坏面积和直接经济损失虽均显著增加,且随烈度增大两者增加量越来越大,但房屋破坏比例显著降低;遭受低、高不同地震烈度条件下,研究区震灾损失风险差异显著:遭受低地震烈度时,砖混和钢混房屋的增加有效降低了房屋的破坏率、破坏面积和破坏等级,利于降低震灾损失风险;但遭受高地震烈度时,这类房屋也出现了大面积和高等级的破坏,因此在某种程度上增加了震灾损失风险;若1976年唐山大地震在不同代表时期重现,房屋震灾损失风险显著增加。2009年房屋破坏面积是1976年的6倍,直接经济损失是1976年的28倍。

Based on our previous researches and taking the year 1976,1995,2002 and 2009 as the repre- sentative reference time periods, the temporal and spatial changes of vulnerabilities and loss risks of building groups from seismic disaster of the Tangshan area in the last more than thirty years have been analyzed mainly through high-resolution remote sensing-based method and scenario earthquake analyti- cal method. The main achievements are concluded as follows： 1 ） The total construction area of all buildings increased four times over the period from 1976 to 2009; the increased area is distributed mainly in the western part of the study area; and the structure vulnerability of buildings reduced grad- ually. 2） Under the earthquake scenarios of intensity VI - XI ,both damaged building areas and direct economic losses increased significantly, and with the increase of intensity, the increments of both were more remarkable, but the area ratios of buildings were gradually reduced. 3 ） Under the earthquake sce- narios of low intensity and high intensity, the loss risks differed greatly. Under the low intensity, be- cause of the increased number of brick-concrete and reinforced concrete buildings which have better anti-seismic performance, the damage ratio, damage area growth and damage degree all reduced signif- icantly. So, buildings with good anti-seismic performance can reduce effectively the loss risk from earthquake of low intensity. Under the high intensity, however, more such buildings were damaged. In a sense,the loss risks increased. 4）If the 1976 Tangshan earthquake had occurred in 2009 ,the dam- age areas and economic losses of buildings would be six times and twenty-eight times more than that of 1976, respectively.