不同设防水准下场地液化震害风险差异性研究  

Study on difference of risk of earthquake liquefaction damages at different fortification levels

作　　者：袁近远 王兰民[1,3] 汪云龙[1] 袁晓铭[1] YUAN Jinyuan;WANG Lanmin;WANG Yunlong;YUAN Xiaoming(Institute of Engineering Mechanics,Key Laboratory of Earthquake Engineering and Engineering Vibration of China Earthquake Administration,Harbin,Heilongjiang 150080,China;Heilongjiang University of Science and Technology,Harbin,Heilongjiang 150027,China;Lanzhou Institute of Seismology,China Earthquake Administration,Lanzhou,Gansu 730000,China)

机构地区：[1]中国地震局工程力学研究所、中国地震局地震工程与工程振动重点实验室,黑龙江哈尔滨150080 [2]黑龙江科技大学,黑龙江哈尔滨150027 [3]中国地震局兰州地震研究所,甘肃兰州730000

出　　处：《岩石力学与工程学报》2023年第1期246-260,共15页Chinese Journal of Rock Mechanics and Engineering

基　　金：中国地震局公益性研究所基本科研业务费专项(2019C07);国家自然科学基金重点项目(U1939209);黑龙江省自然科学基金重点项目(ZD2019E009)。

摘　　要：设防水准是决定液化灾害防御效果的重要因素,但目前不同设防水准下场地液化震害风险差异性认识尚少,以至于我国建(构)筑、公路、铁路、水运、电力等工程领域的抗震规范迄今仍采用基本(中震)地震动作为场地液化震害的设防指标。建立简化模型,以较为成熟和工程上能够接受的场地液化分析方法为基础,推导出基本(中震)地震动、罕遇(大震)地震动和极罕遇(巨震)地震动下场地液化震害风险计算公式,讨论3种设防水准下场地液化震害风险的差异性,并通过2021年我国青海玛多7.4级地震中液化震害现象的对比分析,论证了对场地液化进行大震设防的必要性。研究表明:3种不同设防水准下场地液化震害风险变化显著,随地震动作用水平增大,震害风险明显增强;就我国分布广泛的七度区和八度区内的工程场地来说,以最不利为原则,对于中震作用下接近液化、轻微液化和中等液化的场地,当考虑大震和巨震地震动作用时,场地的液化指数及其概率水平都有大幅提升,液化等级至少提高一级,大部分会提升两级,部分提高三级,发生概率则提高20%~30%,且达到高和极高风险水平;2021年玛多7.4级地震中,液化设防的地震动水平、实际遭受的地震动强度、场地液化部位和程度以及桥梁破坏部位和程度这四者之间存在良好对应关系,表明了该理论推导的正确性和液化大震设防的必要性。从“大震不倒”和抗震韧性设防目标的一致性出发,我国相关工程抗震设计规范中场地液化设防地震动不仅要采用基本峰值加速度,而且应将大震峰值加速度作为场地液化变形控制的设防值。The fortification level is an important factor to determine the effect of liquefaction disaster prevention.However,there is still less knowledge on the difference of risk of earthquake liquefaction damages under different fortification levels,and as a result,the seismic codes of building and structure engineering,highway engineering,railway engineering,water transportation engineering in China still adopt basic seismic ground motion as the fortification index to deal with site liquefaction hazards.A simplified model is set up,and based on mature and engineering acceptable site liquefaction analysis methods,the formulas for calculating the liquefaction-induced damage risk under basic seismic ground motion(moderate earthquake),rare seismic ground motion(rare earthquake)and extremely rare seismic ground motion(huge earthquake)are derived.The difference of liquefaction-induced damage under three fortification levels is discussed,and based on the comparative analysis of liquefaction damages caused by the 2021 Maduo M7.4 earthquake,the necessity of fortification against site liquefaction under rare earthquake is demonstrated.The results show that the liquefaction-induced damage risk varies significantly under the three different fortification levels and the liquefaction-induced damage risk increases obviously when the level of seismic ground motion increases.In terms of the engineering sites in seventh and eighth grade regions widely distributed in China,for the near liquefaction site and slight,medium liquefaction sties,under the rare and extremely rare seismic ground motions,site liquefaction index and its possibility both have a sharp rise.On the principle of the most disadvantageous,liquefaction index at least will be increased by at least one grade,most by two grades,partly by three grades,and the occurrence probability is increased by 20%–30%,reaching high and very high levels.There is a good correspondence between the seismic ground motion level of liquefaction fortification,actual seismic ground motion intens

关 键 词：土力学 地震动水平 液化震害风险 玛多7.4级地震 基本地震动设防 液化大震设防 

分 类 号：TU43[建筑科学—岩土工程]