红层溶蚀对岩溶塌陷的作用机制研究

In South China, the karst collapses in the red beds area, mainly the red clastic rocks cemented with soluble substances or containing carbonates gravels, often occur in recent years, even accompany with emergence of giant collapse hole (tiankeng). Compared with the pure carbonate strata characterized by hard rock and strong karst development, the red beds strata widely distributed in China have own specificity, such as large lithofacies variability, weak diagenesis and complex corrosion mechanism of the soluble substances. Low strength and soluble red beds not only provide room for hollowing out and loss of the overlying loose strata, but also cause collapses, which may be the roof collapse of the red beds karst cave, even the entire red beds roof collapse. Therefore, this project aims at the relation between red beds corrosion and karst collapse formation and development, choose Datansha Island in the middle of Guanghua basin as work place to launch investigation. Based on the work foundation of the geological survey project “Investigation of karst collapse in the Pearl River Delta region”, through supplementary investigation and detection in the field and test analysis and simulation in the lab, the types and distribution of the red beds soluble rocks are found out，the mechanism features of the red beds corrosion are researched. Further, the control action of the red beds corrosion on the karst collapse formation and distribution, the impact of the soluble red beds on the karst collapse development and evolution is investigated, which will supply scientific basis and technical support for risk assessment and prevention treatment of karst collapse geological hazard in red beds area.

在我国南方，以可溶物质胶结的或含碳酸盐岩砾石的红色碎屑岩为主的红层地区，近年来岩溶塌陷多有发生，且出现巨型塌陷坑（天坑）的情况。与岩溶发育强烈且坚硬的纯碳酸盐地层相比，红层具有岩相变化大，成岩作用差，所含易溶盐类溶蚀机理复杂等特殊性。低强度的可溶红层，不但能为上覆松散层掏空流失提供空间，而且有产生红层溶洞顶板垮塌，甚至是整个红层作为顶板垮塌的可能。因此本项目拟以研究红层溶蚀与岩溶塌陷的关系为目标，选择广花盆地中部大坦沙岛为典型研究区。在地调项目“珠三角地区岩溶塌陷调查”的工作基础上，通过实地补充勘察探测和室内试验分析模拟，查明红层可溶岩类型和分布，探讨红层溶蚀机理特征。进而研究红层溶蚀对岩溶塌陷形成分布的控制作用和可溶红层对岩溶塌陷发育演化的影响作用，为红层地区岩溶塌陷地质灾害的风险评估和防治处理提供科学依据。

在我国南方，以可溶物质胶结的或含碳酸盐岩砾石的红色碎屑岩为主的红层地区，近年来岩溶塌陷多有发生，且出现巨型塌陷坑（天坑）的情况。与岩溶发育强烈且坚硬的纯碳酸盐地层相比，红层具有岩相变化大，成岩作用差，所含易溶盐类溶蚀机理复杂等特殊性。低强度的可溶红层，不但能为上覆松散层掏空流失提供空间，而且有产生红层溶洞顶板垮塌，甚至是整个红层作为顶板垮塌的可能。因此本项目拟以研究红层溶蚀与岩溶塌陷的关系为目标，选择广花盆地中部大坦沙岛为典型研究区。在地调项目“珠三角地区岩溶塌陷调查”的工作基础上，通过实地补充勘察探测和室内试验分析模拟，查明红层可溶岩类型和分布，探讨红层溶蚀机理特征。.中国岩溶地区面积广阔，岩溶发育类型多样。其中我国南方地区红层中出现的岩溶现象较为特殊：可溶岩类型复杂，成岩作用差，溶蚀机理多样，还易风化崩解。红层岩溶主要存在于以可溶物质胶结的或含碳酸盐岩砾石的红色沉积岩为主的地区。红层岩溶的特点可以概括为：①可溶岩类型复杂，其溶蚀机理多样。②成岩作用差，力学强度低，易风化崩解。③与地质构造密切相关。红层岩溶地区不但会出现覆盖型岩溶区的土层塌陷，而且由于其特殊的岩溶作用还可能出现了基岩塌陷。根据红层岩溶地区地质结构，其塌陷模式可概化为红层上覆松散层塌陷，红层溶洞顶板垮塌以及红层整体垮塌三类。.进而研究红层溶蚀对岩溶塌陷形成分布的控制作用和可溶红层对岩溶塌陷发育演化的影响作用，为红层地区岩溶塌陷地质灾害的风险评估和防治处理提供科学依据。