唐山市基岩破裂对地震动的影响分析
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摘要
我国是世界上大陆地震发生最多的国家之一,20世纪全球2次死亡人数大于20万的地震都发生在中国。震害的发生受到场地条件和基岩条件的共同影响,而迄今为此,对场地影响的考虑相对比较成熟,对基岩的影响则相对考虑较少。大陆地震的发生是由活断层的活动而致,而地下岩体快速破裂错动传播是导致地震的直接原因,通过地下基岩能量、位移和破裂概率等指标的数值计算,可以进一步分析其对地震动的影响。基于基岩破裂指标的分布,应用人工神经网络方法,确定了基岩破裂指标与地震影响系数之间的关系,得到了地震影响系数计算模型,进而计算得到唐山市地震影响系数分布。根据计算结果,对城市规划和工程建设提出了几点建议。
China is the country with land earthquake taking place frequently. All the two big earthquakes during 20 century in the world,which caused more than 200 000 lives lost,took place in China. Land earthquake is mainly caused by fault activity and quick transmission of earthquake waves in land. Earthquake disaster is controlled by two main factors,site condition and base rock condition. The consideration of site condition is usually made in earthquake disaster prediction,but less attention is paid to base rock condition. As densely populated area with highly developed civilization,city shows obvious fragility to natural disasters. Tangshan,as a heavy industry city with six million populations,is located in the north east of Heibei province,China,and has been frequently suffered from natural disasters such as earthquake,karst collapse and ground collapse. The Big Earthquake in 1976 of Tangshan still remained freshly in peoples memory,which caused 240 000 lives lost,and especial attention has been paid to disaster resistance. Earthquake affecting coefficient is one of the most important factors for earthquake security evaluation,but it is very difficult to determine earthquake affecting coefficient accurately because of the influence of underground rock conditions. Traditional methods couldn抰 analyse well earthquake resistance in city and engineering construction. Based on numerical calculating results of energy,and cracking probality in undeground base rock,the influences of these factors on earthquake affecting conefficient are analyzed. According to the base rock condition parameters,neural network method is applied,and the relation among earthquake affecting coefficient,energy,displacement and cracking probablity of undergroud rock is determined. The calculating model of earthquake affecting coefficient is constructed and the distribution of earthquake affecting coefficient in Tangshan city is calculated. From the calculating results,it is found that the earthquake affecting conefficient in southeast of Tangshan city is bigger than 0.48,even more than 0.64 somewhere,which means that the intensity of earthquake disaster is 10 degree. At last,some suggestions for city planning and engineering construction are given.
China is the country with land earthquake taking place frequently. All the two big earthquakes during 20 century in the world,which caused more than 200 000 lives lost,took place in China. Land earthquake is mainly caused by fault activity and quick transmission of earthquake waves in land. Earthquake disaster is controlled by two main factors,site condition and base rock condition. The consideration of site condition is usually made in earthquake disaster prediction,but less attention is paid to base rock condition. As densely populated area with highly developed civilization,city shows obvious fragility to natural disasters. Tangshan,as a heavy industry city with six million populations,is located in the north east of Heibei province,China,and has been frequently suffered from natural disasters such as earthquake,karst collapse and ground collapse. The Big Earthquake in 1976 of Tangshan still remained freshly in peoples memory,which caused 240 000 lives lost,and especial attention has been paid to disaster resistance. Earthquake affecting coefficient is one of the most important factors for earthquake security evaluation,but it is very difficult to determine earthquake affecting coefficient accurately because of the influence of underground rock conditions. Traditional methods couldn抰 analyse well earthquake resistance in city and engineering construction. Based on numerical calculating results of energy,and cracking probality in undeground base rock,the influences of these factors on earthquake affecting conefficient are analyzed. According to the base rock condition parameters,neural network method is applied,and the relation among earthquake affecting coefficient,energy,displacement and cracking probablity of undergroud rock is determined. The calculating model of earthquake affecting coefficient is constructed and the distribution of earthquake affecting coefficient in Tangshan city is calculated. From the calculating results,it is found that the earthquake affecting conefficient in southeast of Tangshan city is bigger than 0.48,even more than 0.64 somewhere,which means that the intensity of earthquake disaster is 10 degree. At last,some suggestions for city planning and engineering construction are given.
引文
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2崔江余,杜修力.重大工程设定地震动确定[J].世界地震工程,2000,16(4):25～28
3温瑞智,周正华,孙平善等.断层场地地震动分析[J].地震工程与工程振动,2002,22(1):21～27
4陈艳华,朱庆杰,苏幼坡.基于格里菲斯准则的地下岩体天然裂缝分布的有限元模拟研究[J].岩石力学与工程学报,2003,22(3):364～369
5朱庆杰,姜耀俭,陈艳华等.轮南地区奥陶系天然裂缝的发育机理及其对流体活动的控制[J].中国安全科学学报,2003,13(1):53～58
6张振江,翟振生,蔡华昌.河北北部场地特征及震害预测[J].华北地震科学,1998,16(4):58～65
7肖和平.地震成灾机制分析[J].中国地质灾害与防治学报,2000,11(4):101～102
8冯夏庭,王川庭,陈四利.受环境侵蚀的岩石细观破裂过程试验与实时观测[J].岩石力学与工程学报,2002,21(7):935～939
9朱庆杰,苏幼坡,刘廷权.灾害危险性评价的神经网络预测模型[J].电子与信息学报,2003,22(增):17～22
10朱庆杰,苏幼坡,陈静.基于神经网络模型的地下岩溶分布预测[J].岩石力学与工程学报,2003,22(增):2378～2381
11李建华,郝书俭,胡玉台等.1976年唐山地震发震断裂的活动性研究[J].地震地质,1998,10(1):27～33
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