东江口崩塌灾害特征及稳定性评价

Disaster Characteristic and Stability Evaluation of Collapse in Dongjiangkou

东江口崩塌危岩带位于北京市房山区北部,地貌类型为中低山区,主要组成物质为强风化玄武岩,平面呈不规则带状,总体积约6300m^3。危岩带变形主要受裂隙及优势结构面发育的控制,为小型-滑移式崩塌。危岩带东侧受裂缝L1-L3切割制,形成体积为300m^3的危岩单体,失稳方向为60°;西侧主要受裂缝L4-L5以及优势结构面控制,失稳方向为307°。采用赤平投影与定量计算的方法评价危岩带稳定性,评价结果:在天然工况下,危岩体东侧及中、西侧均处于基本稳定状态;在降水等不利工况条件下,危岩带东侧处于不稳定状态,中、西侧处于欠稳定状态。影响东江口危岩带稳定性的主要因素为人类工程活动与降水。

Collapse in Dongjiangkou is located in the north of Fangshan District.Its landform type is medium and low mountainous area,which is composed of strong weathered basalt with irregular strips,the total volume of about 6300 m^3.Dangerous rock deformation is mainly controlled by the development of fissures and dominant structural planes,belonging to small-slip collapse.The eastern side of the dangerous rock belt is cut by the cracks LI to L3,to form a dangerous rock monomer with a volume of 300 m^3,the instability direction at 60°;the middle and western sides of the dangerous rock belt are controlled by the cracks L4 to L5,the instability direction at 307°.The paper studies the mechanism of collapse and deformation,and the stability of the dangerous rock belt,by the method of red plane projection and quantitative calculation.After evaluating the stability,it concludes that,in natural conditions,the dangerous rock mass are basically in a stable state;under adverse operating conditions such as precipitation,the eastern side of the dangerous rock belt is unstable;the middle and western sides of the dangerous rock belt are in an unstable state.The main factors affecting the stability of dangerous rock belts in Dongjiangkou are human engineering activities and precipitation.