基于修正岩土体强度参数的简化纽马克位移法地震滑坡危险性快速评估技术

A method for seismic landslide hazard assessment using simplified Newmark displacement model based on modified strength parameters of rock mass

  • 摘要: 地震滑坡危险性评估可为震后应急响应等提供科学的决策依据。纽马克位移法可不依赖同震滑坡编目快速评估同震滑坡危险性。工程岩体物理力学参数是该方法的核心参数之一,但其赋值过于单一,难以反映复杂地质背景下岩体强度的空间差异性。针对上述问题,本文在分析地震滑坡影响因子的基础上,选择距断层距离、高程和距水系距离作为影响岩体强度的评价指标并建立岩体强度评价模型,获得区域岩体强度修正系数,进而修正传统方法的临界加速度。结合震后的即时地震动峰值加速度,采用简化纽马克位移法计算边坡累积位移,开展地震滑坡危险性快速评估,并以汶川MW7.9地震的地震滑坡危险性评估为例验证本文方法。结果表明,相对于传统方法,本文方法划分的地震滑坡危险区与同震滑坡分布更加一致。

     

    Abstract: Rapid assessment of seismic landslide hazard can provide a scientific basis fordecision-making aimed at post-earthquake emergency response. The Newmark displacement model can quickly assess the seismic landslide hazard after an earthquake without co-seismic landslide inventory. However, as one of the main parameters of the Newmark displacement model, physical and mechanical parameters of the rock mass assigned by traditional methods are too single to reflect the spatial differences of real rock mass strength under complex geological background. To tackle this issue, the distance to the fault, the elevation, and the distance to the river were selected as the evaluation indexes affecting the strength of rock mass, and the evaluation model of rock mass strength was established to obtain the regional rock mass strength modified coefficient, and then the critical acceleration obtained by the traditional method was modified. Combined with the instantaneous peak ground acceleration after an earthquake, the simplified Newmark empirical displacement model was used to calculate the slope cumulative displacement, and the rapid assessment of seismic landslide hazard was conducted. The Wenchuan MW7.9 earthquake was selected as the studied area to validate the performance of the presented method. Results show that the seismic landslide hazard area divided by the presented method is more consistent with the actual co-seismic landslide distribution compared to traditional method. The presented method in this paper can be used for rapid assessment of seismic landslide hazard, which has important reference value for guiding post-earthquake emergency rescue and land planning and also provides a new idea for the subsequent establishment of a basic geological spatial database.

     

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