摘要
大部分情况下,天坑都是现代暗河通道洞顶塌陷而成。塌陷的扩大造成暗河通道的阻塞和改道,使得水力梯度变陡,溶蚀和侵蚀增强。可以说,天坑大部分空间体积的形成都是地下河大规模搬运崩塌堆积物的结果。强烈变化的大流量是搬运崩塌堆积的最佳条件,而暗河通道的改道和扩大又进一步加强了塌陷作用。与区域裂隙模式不同,新的裂隙随着崩塌周围应力释放而扩张。与原始洞穴通道形成相比,大规模天坑的形成都是源于这些作用。
Tiankengs are formed most commonly by the collapse of bedrock into underlying caves that contain active rivers. The collapse propagates itself by blocking and diverting the underground streams, so that hydraulic gradients become steeper and the solutional and erosional capacities are enhanced. Most of the volume of a tiankeng is produced by removal of mass by the cave streams. A large and fluctuating discharge is most favorable. As diversion passages form and enlarge, they foster further collapse and diversion. Stress release around the collapse encourages the opening of new fractures with trends that differ from regional fracture patterns. These processes account for the large scale of tiankengs in comparison to the original cave passages.
出处
《中国岩溶》
CAS
CSCD
北大核心
2006年第B08期71-78,共8页
Carsologica Sinica
关键词
天坑
水力机制
水力梯度
洞穴
塌陷
Tiankeng
Tydraulic process
Hydraulic gradient
Cave
Collapse
