中国西部岩石高边坡应力场特征及其卸荷破裂机理
GEO-STRESS DISTRIBUTION AND UNLOADING FRACTURING MECHANISM OF HIGH ROCK SLOPES IN WESTERN PART OF CHINA
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摘要: 大量的工程实践表明,中国西部地区,尤其是西南地区,由于所处青藏高原东侧的特殊地域地质环境条件,这一地区的岩石工程普遍受到地应力,尤其是高地应力及伴随的卸荷效应的影响;卸荷及卸荷带的问题构成了这一地区地表岩石工程的根本性问题之一。卸荷带的形成通过对岩体结构的表生改造,不仅影响和改变了作为建(构)筑物地基和环境的工程岩体的结构基础,弱化了其承载能力,而且,也构成了其他工程地质作用和诸如地下水活动等物质与能量交换的边界,影响了工程岩体的稳定性。本文分析了中国西南地区区域高地应力环境的形成和集中模式,讨论了岩石高边坡应力场的基本特征,提出了"驼峰应力分布"的基本模式。在此基础上,重点讨论了河谷高边坡应力释放及其伴随的浅表生破裂体系的形成机理与基本规律,阐述了这套破裂体系的工程地质意义。Abstract: High geo-stress and its reduced epigenetic fracturing during unloading process has great significance to the rock engineering in southwestern China because of the exists of local high geo-stress in this area. The basic laws summarized as 3 basic models about regional geo-stress distribution and so called "camel type distribution" of a typical rock slope are revealed in this paper. Based on a lot of field evidences related to geo-stress release in rock slope, the author concludes the near surface fracturing accompanying with a river's cutting down or surface excavation as 4 epigenetic recreation conceptual models. The formation mechanism and engineering geological significance of these models are also discussed in this paper.
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