Abstract
The stability of the surrounding rock masses of underground powerhouses is always emphasized during the construction period. With the general trends toward large-scale, complex geological conditions and the rapid construction progress of underground powerhouses, deformation and failure issues of the surrounding rock mass can emerge, putting the safety of construction and operation in jeopardy and causing enormous economic loss. To solve these problems, an understanding of the origins and key affecting factors is required. Based on domestic large-scale underground powerhouse cases in the past two decades, key factors affecting the deformation and failure of the surrounding rock mass are summarized in this paper. Among these factors, the two most fundamental factors are the rock mass properties and in situ stress, which impart tremendous impacts on surrounding rock mass stability in a number of cases. Excavation is a prerequisite of surrounding rock mass failure and support that is classified as part of the construction process and plays a pivotal role in preventing and arresting deformation and failure. Additionally, the layout and structure of the powerhouse are consequential. The interrelation and interaction of these factors are discussed at the end of this paper. The results can hopefully advance the understanding of the deformation and failure of surrounding rock masses and provide a reference for design and construction with respect to hydroelectric underground powerhouses.
Highlights
With the economic boom came the vigorous development of hydropower resources in China
Due to abundant hydropower resources, a number of hydropower stations have been constructed in southwest China, which has complex geological conditions and topography characterized by high mountains and deep valleys
Recent development of underground powerhouses in hydropower stations has witnessed a new trend of large-scale, complex geological conditions and fast construction progress
Summary
With the economic boom came the vigorous development of hydropower resources in China. The spacing between caverns should be determined via overall analysis on factors such as layout requirements, geological conditions, stress and deformation of the surrounding rock mass, section geometry, construction method, and operation conditions. Erefore, because of more intense unloading triggered by excavation disturbance, the surrounding rock mass at the intersection of caverns has a higher deformation rate and greater risk of large deformation, spoiling the stability of the underground powerhouse. Ough sharing different sizes or numbers of intersecting caverns, these intersections may experience varying degrees of instability problems from the surrounding rock mass, for example, large deformation, circumferential cracks, or local collapse, posing a threat to the safety of construction and operation. In regard to the surrounding rock mass stability, the intersection of caverns is a factor of nonnegligible importance as well
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