IMHE OpenIR  > 山地灾害与地表过程重点实验室
泥石流作用下建筑物易损性评价方法
Alternative TitleVulnerability assessment of building to debris flow hazard
Language中文
曾超
Thesis Advisor崔鹏
2014
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Name博士
Degree Discipline自然地理学
Keyword泥石流 建筑物 易损性 冲击力 结构动力响应
Abstract泥石流作用下建筑物易损性研究作为灾害风险分析的必要环节,既可直接指导城镇建筑物规划和结构抗灾设计,也能为城镇泥石流风险的定量预测及减灾措施的实施提供依据。论文以调查获取的建筑物破坏样本为基础,采用量纲分析和回归统计的手段建立了单沟和单体尺度建筑物易损性评价经验模型,实现了泥石流扇形地易损性区划。为深入研究建筑物受泥石流作用的动态响应,阐释易损性力学机理。采用结构有限元方法分析了建筑物受冲后连续倒塌过程,实现了损失的定量化;并通过水槽实验,揭示了泥石流浆体和大颗粒冲击力随时间变化和垂向分布规律,为动力学计算提供参数;最后结合冲击力与建筑物结构强度参数,采用塑性力学理论计算了砖混和框架结构建筑物承重构件受泥石流冲击破坏的临界条件,为形成建筑物易损性力学模型提供基础。主要研究结果如下: (1)通过灾史记录、实地调查、遥感调查和文献查阅收集了典型泥石流灾害事件中建筑物破坏样本270余份。依据野外调查经验和样本数据,提出了较为实用和科学的泥石流灾害建筑物调查流程,归纳了泥石流对建筑物破坏方式与模式。 (2)以建筑物破坏样本数据为基础,选取近似冲击能量的泥石流强度指标IDF(v2h),统计了5种强度条件下建筑物产生完全破坏到淤埋损坏的可能性,形成了单沟泥石流易损性评价方法。结果表明:当IDF大于1000 m3·s-2,建筑物必完全破坏;其值为100-1000 m3·s-2时,完全破坏可能性为70%,29%可能为结构破坏;为10-100 m3·s-2时,结构破坏的可能性达67%,完全破坏仍占24%;为1-10 m3·s-2,以淤埋和部分结构破坏为主,占78%;小于1 m3·s-2后,水淹的可能性达86%。单沟泥石流扇形地内:r/R为0-0.65且η/θ为0-0.43范围内为建筑物重度易损区;r/R为0.65-0.8且η/θ为0.43-0.78范围为中度易损区;r/R为0.8-0.92且η/θ为0.78-1范围为轻度易损区;r/R为0.92-1.1且η/θ为1-1.2范围为微小易损区。 (3)针对前人易损性曲线指标选取单一、适用性差且无物理意义的问题。通过分析泥石流动力学指标与单个建筑物抵抗力因子的关系,建立了具有物理意义的砖混和框架结构建筑物易损性定量评价模型。对于砖混结构:当泥石流动压力超过25Kpa或流速超过4m/s,建筑物完全破坏,小于上述值时,以流深和开口(门窗)比组合的强度指标与易损度呈二次函数关系;对框架结构建筑,采用泥石流冲击力(F)、柱体极限抗剪力(Tu)及建筑长短轴比值(L/W)作为强度指标,统计结果显示各指标与易损度间满足Weibull和Exponential分布函数。 (4)泥石流浆体和大颗粒冲击频率的临界值为2Hz,浆体连续冲击过程可采用3个阶段的线性函数描述,大颗粒冲击因其具有随机性而采用频率表达。浆体垂向分布可分为两层,底层为泥石流直接冲击,可采用指数分布函数拟合,上层压力为雍高导致的压力,可采用线性函数拟合。水动力学公式中待定系数α与流体Fr数关系呈幂函数关系,得到弱化尺寸效应的浆体动压力计算式。 (5)建筑物支撑构件的破坏数量可表征其损坏程度,当其失去1根构件时,其损失比例为0.17;丧失2-3根时,损失比为0.42-0.81;破坏构件超过4根,建筑物将失去支撑而倒塌。其主要支撑构件(梁柱)的破坏可采用塑性铰描述,计算得到构件破坏临界泥石流流速为4.2 -10.4 m/s(固端2点塑性铰)、8.3-24.9 m/s(固端-跨中3点塑性铰)及7.3-15.7 m/s(剪切破坏)。 (6)将建筑物易损性经验模型与破坏临界条件应用于七盘沟“7.10”特大泥石流灾害事件的计算。据单体和单沟泥石流建筑物易损性模型计算的经济损失较为接近,且通过建筑物破坏样本对比,显示出易损度经验模型、力学计算与野外调查得出的结果具有较高的一致性,这也佐证了本文易损性评价模型和力学计算结果的精度与适用性。
Other AbstractStudy the vulnerability of buildings under debris flow impact is essential to the hazard risk analysis. It not only provide guidance to the urban planning and building design at hazards prone area, but also support the quantification of debris flow risk and the associated mitigation measures. Based on the damaged buildings inventories, A building vulnerability assessment method and empirical model with physical significance is established based on the statistic relationship between debris flow dynamic factors (velocity, depth and impaction) and structure resistance factor. In order to study the building’s dynamic response to debris flow impaction, structure analysis using FEM is carried out. The progressive collapse of building due to structure member failure under debris flow impact is simulated and the structure damage and lost on internal fitting is quantified. Impact force is one of the most important parameter to calculate the dynamic response. In view of this, flume experiment is conducted to investigate the vertical distribution of impact force of debris flow slurry and large particle and the time-history variation. The slurry impact calculation formula is modified base on the experiment results. The critical conditions for masonry and frame structure member failure under debris flow impact are calculated using plastic analysis of structure mechanics. This provides the foundation to build a dynamic model for single building vulnerability assessment. Main results has been achieved as follow: (1)By going through historical hazards records, field investigation, remote sensing interpretation and literature review, author have collected over 270 records which delineate the buildings damage during debris flow events. The damage pattern and failure mode of buildings under debris flow action is summarized based on these records. (2)Debris flow impact index IDF(v2h)determines the damage degree to buildings distribute in debris flow fan and gully. The buildings are certain to be damaged completely when the IDF is more than 1000 m3s-2. And there will be 70% possibility for buildings damage completely, 29% possibility appears to structure damage, when IDF is between 100 m3s-2 and 1000 m3s-2. The IDF decrease to 10-100 m3s-2, buildings would subject to structure damage with 67% possibility, and with 24% possibility completely damage. If IDF is 1-10 m3s-2, the debris flow would causes buried and partially structure damage for the buildings. Once IDF less than 1 m3?s-2,there will be 78% possibility for buildings subject to flooding damaged. The most vulnerable area for buildings in the debris flow fans is r/R(The r is the distance between buildings and outlet, The R is the maximum run out distance of debris flow)less than 0.65 and η/θ (The η is the deviated angle between buildings and main stream line, the θ is the maximum angle of debris flow fan) less than 0.43. And the buildings are medium vulnerable within area that r/R is 0.65-0.8 and η/θ is 0.43-0.78. The mild vulnerable area within r/R between 0.8 and 0.92 , and η/θ is between 0.78 and 1. The slight vulnerable area with r/R 0.92-1.1 and η/θ 1-1.2. (3)The masonry structure would be damaged completely, when debris flow dynamic pressure is more than 25kPa or its velocity is more than 4m/s. If the pressure and velocity are less than those values, the vulnerability can be calculated with debris flow depth by considering the effect of the building openings which let debris flow intrude. The vulnerability of Reinforced Concrete building has high correlation with the impact force of debris flow, the ultimate shear resistance of columns, and the impact direction between debris flow and building face. Therefore, Empirical models with Weibull and Exponential functional forms are established to quantify the relations. (4)The FFT method is used to analyses the frequency distribution of impact signals of debris flow. The critical frequency is 2Hz for separating the impact signals of slurry a
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/7869
Collection山地灾害与地表过程重点实验室
Recommended Citation
GB/T 7714
曾超. 泥石流作用下建筑物易损性评价方法[D]. 北京. 中国科学院研究生院,2014.
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