重力侵蚀作用下昔格达地层滑坡特征分析

ANALYSIS OF LANDSLIDE CHARACTERISTICS IN XIGEDA STRATA DUE TO GRAVITATIONAL EROSION

昔格达地层性质特殊,强度低,遇水极易崩解,在地质构造与水力作用下,极易发生滑塌。在调查研究的基础上,介绍了文武坡喇嘛溪沟重力侵蚀作用下昔格达地层滑坡的地层岩性、地质构造等工程地质条件及地表水、地下水等水文地质条件,重点分析了滑坡形成原因及影响因素,认为滑坡发生的易发斜坡坡度、坡角与高度,并按坡度对斜坡按危险性分成了3级,得出了滑坡易发坡度,为滑坡稳定性评价提供了依据,最后提出了适合于地质条件的填方反压结合排水沟的整治措施。

Ya＇an to Lugu expressway is a part of the Beijing to Kunming expressway. The Lama stream is spanned by the Lama Stream Bridge along the Ya＇an to Lugu expressway. To investigate engineering geological conditions at the bridge, a geological survey and field reconnaissance were conducted prior to the bridge construction. It was found that the geoenvironmental conditions near and around the planned bridge site were very complicated. The so -called Xigeda strata have low strength and collapsing characteristics, which can be strongly affected by water. Under the action of water and geological structure, landslide can easily occur in slopes comprising the Xigeda strata. Base on the ground investigations at the Wenwu slope on the Lama stream along the Ya＇an to Lugu expressway, this paper presents the engineering geologic and hydrogeological conditions of the landslides comprising the Xigeda strata. The paper gives results on the properties of Xigeda strata, the geological structure and groundwater. It analyzes the causes and contributing factors, finds the optimal slope gradients, the optimal slope shapes, the angle and height of slopes sensitive to landslide. It grades the dangerous degrees according to angle of slope. It provides a basis for further evaluation of slope stability. Finally, it presents some reasonable reinforcements, fill and compression and drainage measures adaptable to the geological conditions.