| 三峡地区泥灰质岩石斜坡带岩溶作用及其对工程稳定性的影响 |
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| 关键词:water karst process construction stability muddy limestone Three Gorges region |
| 基金项目:三峡移民开发局基金（编号：9707,9904） |
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| Karst Process and Its Impact on Construction Stability of the Slope Terrain within Muddy Limestone in the Three Gorges Region |
| The study of karst in mud limestone is a weak link in karst geology. The connection of construction stability with karstification is a new project for the evaluation and control of geohazards in the karst region. The karst in mud limestone of Triassic Badong Formation (T_2b) is an important geological problem newly discovered in the Three Gorges Region. Due to the unloading and loose- ning brought about by tectonic shattering and river cutting, the mud limestone becomes favorable for water infiltration and karstification. Water is the fluxing agent of karstification. The rainwater is the main resource of surface water and groundwater in the slope terrain of the gorges, and there is plentiful rainwater in the semitropical Three Gorges. Based on the analysis of chemical contents of 15 water samples of different types and related calculations, it is found that the rainwater is acid and has low saturation index (SI) of calcite, and therefore it bears strong dissolution capability and strongly dissolves the mud limestone in the process of its migration at or beneath the surface. There exist different conditions of surface water and groundwater in different landform parts and tectonic locations where there are different karstification intensities and types at surface and in the depth. Generally speaking, there exists strong karstification where the discharge is large, and at places of temporary flow there exists high karstification where the water flow is slow. Karstification has led to a series of variations in the composition and structure of rocks, which degraded the mechanical intensity, and brought about uneven subsidence, fissuring, landslide, collapse, mud flow and cave-in of rockmass in geological history. It is also shown by the test and calculation that all the rainwater, surface water, groundwater, river water and tap water have dissolution capacity and, in future, the karstification and hydro-induction may result in uneven subsidence, fissuring, landslide, collapse, mud flow and cave-in of the construction foundation. These factors, in turn, can destroy the construction stability. To control the geo-ha- zards in the region, it is of key importance to prevent water from infiltration into the foundation within mud limestone. It is suggested that the karst in slope terrain within mud limestone in Three Gorges region should be investigated in detail. |
| ZHANG Jia-gui.2005.Karst Process and Its Impact on Construction Stability of the Slope Terrain within Muddy Limestone in the Three Gorges Region[J].Acta Geoscientica Sinica,26(6):565-569. |
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