桂林市岩溶塌陷成因类型与时空分布特征

Genetic types and distributive characters of karst collapses in Guilin urban and suburban area, Guangxi Province

应用对比分析的方法，研究了近４０年来发生在桂林市区及近郊３００ｋｍ２范围内的６５４个岩溶塌陷的成 因类型与时空分布特征。结果显示，桂林市岩溶塌陷以人为塌陷为主，其中７７．６％的人为塌陷由抽水引起。时间上，岩溶塌陷多发生在冬、春两季，且总体上有逐年增加的趋势；空间上，岩溶塌陷多发生在市区土层厚度小于１０ｍ，且下伏基岩为东村组的峰林（或孤峰）平原和一级阶地内，多发生在张扭性特征明显的ＮＥ向和ＮＷ向断裂带及其交汇部位，并具成群性和成带性的分布特征。上述岩溶塌陷时空分布的不均匀性主要受桂林市的气候、地质条件及人类活动的影响和控制。揭示和掌握岩溶塌陷时空分布的这种不均匀性，对城市的防灾减灾具有重要的现实意义。

By of contrast and analysis, the authors studied the genetic types and distributive characters of 654 karst collapses around Guilin urban and suburan area of 300km2 in last 40 years. This study has shown that these collapses were mostly caused by human activities, and 77.6% of them by municipal groundwater pumping. Temporally, most of karst collapses took place in drought winter and spring seasons, and the collapses show increasing tendency with every year. Spatially, the collapses are distributed in the zones where the thickness of soil layer is less than 10 meters, and the bedrock underneath the soil layer belongs to upper Devonian Dongcun formation(D3d), and the topography is characterized by development of peakforest-plain(or isolated peak-plain) and first-order drainage terraces. Structurally, the collapses are dominantly controlled by northeast and northwest-trending fault zones and their conjunctions, and their distributions are obviously characterized by clusterization and zonation. These irregular distributive characters of karst collapses are mainly affected and controlled by climate, geologic conditions and mankind activity. To reveal and master the irregular distrbutive character will be useful for Guilin to prevent hazard and reduce hazard.