广东沿海陆地地质灾害孕育环境探讨

A STUDY ON THE GEOLOGICAL HAZARD ENVIRONMENT ALONG THE COASTAL AREA OF GUANGDONG

通过广东沿海陆地典型地质灾害事件的统计、调查与研究表明 ,南澳、汕头、揭阳、阳江等地区是潜在地震多发区和强震活跃区 ,地震多出现在NEE、NNW和NW向活动断裂交汇的海湾附近。河流两岸、海岸、交通沿线和城镇区等人类活动区是潜在水土流失、崩塌和滑坡等坡面灾害发育区。降雨强度和持续时间影响不稳定斜坡出现的机率。雷州半岛的地裂缝与地下水活动密切相关 ,雨、旱季节性变化特别是持久的干旱多出现地裂缝现象。隐伏岩溶区过渡抽、排岩溶区地下水是岩溶塌陷形成的直接原因。地面沉降是长期超采地下水 ,特别是深层承压水的结果。软土因其天然含水量大、孔隙比大、压缩性高、强度低和承载力低 ,构成了沿海三角洲与滨海平原区工程建筑的非稳定地基。

The coastal area of Guangdong is characterized by widespread distribution and frequent occurrence of the geo-disasters which have caused considerable property damage and casualties in the past decades.From the investigations and statistic work on representative disasters in detail in the land along the Guangdong coast in recent years it has been confirmed that historically intense earthquakes that occurred in Nan′ao, Shantou, Jieyang, Yangjiang, etc. are highly related to NEE-trending active faults, especially to intersections between the NEE-trending active faults and NE-trending active faults or NW trending active faults. The occurrence of soil erosion, landslips and landslides are the result of a complex interaction among the slope height, slope gradient and rock soil as wall as heavy rainfall and artificial activities. Topographically, natural slopes at riverbanks and along coast, artificial slopes along traffic lines and those in cities and towns are easily occurring zones for soil erosion, landslips and landslides. The temporal and spatial distribution of rainfall will decide the occurrence probability of unstable slope in the area. The ground fissures occurring in Leizhou Peninsula are much related to groundwater activities, dry and rainy season alternations. Particularly, a long dry period will promote ground fissure development. The earth subsidence in karst areas is usually a result of over exploitation for underground water resources, and the soft soil in the delta and coastal plain usually causes the ground to be unstable.