广东沿海陆地主要地质灾害及其控制因素分析

STUDY ON GEOLOGICAL DISASTERS AND THEIR CONTROL FACTORS IN THE COAST LAND OF GUANGDONG

广东沿海不仅是我国经济较为发达的地区 ,同时也是我国地质环境较为脆弱及各类地质灾害较为发育的一个地带。通过地质灾害案例的调查、地质灾害孕育环境、诱发因素等的研究与分析看出 ,南奥、汕头、揭阳、阳江等是历史强震和潜在地震活跃区 ,地震多发生在 NEE、NNW和 NW向活动断裂交汇部位附近。丘陵、台地及其边缘区的河流两岸、海岸、交通沿线、城镇人工切坡等构成了是水土流失、崩塌和滑坡等的多发区。降雨的时空分布直接控制着丘陵和台地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、旱季节性变化利于地裂缝的发育。岩溶塌陷是过度抽、排岩溶区地下水的结果。而地面沉降是长期超采深层承压水的反映。软土构成了沿海三角洲与滨海平原区工程建筑的非稳定地基。地质灾害的防治应采取防为主。

The coast land of Guangdong is not only a relatively developed region in economy,but also is a friable zone in geoenvironment.Based on the investigations and statistic work in detail for representative disasters in the land along the Guangdong coast in recent years it has been confimed that devastating earthquake occurred historically in Nanao,Shantou,Jieyang,Yangjiang etc.are highly related to NEE-trending active faults,especially to intersections of the NEE-trending active faults and NE-trending or NW-trending active faults. The occurrence of soil erosion,rockfalls and landslides is the result of a complex interaction of slope height,slope gradient and rock and soil as wall as heavy rainfall and artifical activities. Topographically, natural slopes in riverbanks and along coast, artifical slopes along traffic lines and in town in the coast land are subject to soil erosion,rockfalls and landslides.The spatio-temporal distribution of rainfall decides the probability of unstable slope occurrence.The ground fissures in the Leizhou Peninsula are highly related to groundwater activities, the alternations from arid to rainy season promote the occurrence of ground fissure.The occurrence of Karst washin and ground sink is triggered by over exploitation underground water,and the soft soil developed in the delta and coast plain commonly cause in stable foundation.