深切河谷初始地应力特点及其对地下工程的影响

Characteristics of initial ground stress field of deep valley and its influence on underground projects

在深切河谷地区修建地下工程,山体不同坡度时会对初始地应力有十分重要的影响。通过数值分析研究了当山坡坡角分别为30°、45°和60°时,在重力场和构造应力条件下山体中在垂直向和水平向典型剖面中初始地应力分布的特点。得出以下结论:1山体同一高程处,地应力的分布特点是先增大后减小的驼峰式。2地下洞室开挖距离坡脚越近,修建后洞室周边的塑性区越大,对于洞室围岩的稳定性越不利。3在研究河谷地区的地应力分布规律和状态时,仅考虑自重作用是不全面的,应该结合区域特性,考虑构造应力的影响。4由于河谷形成过程中的卸荷作用及风化作用,河谷底部构造强烈,产生了大量的应力集中。

The initial ground stress would be impacted by mountain slope in the construction of underground project in alpine and gorge area.The initial ground stress distribution in typical vertical and horizontal profiles of mountain with slope of 30°,45°and 60° were studied under the gravity field and tectonic stress field by numerical analysis.The conclusions are as follows： at the same elevation,the ground stress increases at first and decreases then,and the distribution conforms to a Hump shape distribution; the plastic zone enlarges as the distance of the cavern to the slope toe decreases,which is adverse to stability of round rock mass; For ground stress study in gorge area,the tectonic stress should be taken into account as well as the gravity stress; Due to unloading and weathering effect in the formation process of gorges,the tectonic action is strong at valley bottom and stress concentration occurs.