国道320线雪峰山高速公路隧道地应力场研究

Study on the geostress field in the Xuefeng Mountain expressway tunnel

雪峰山高速公路隧道为上海至瑞丽国道G320主干线湖南省邵阳至怀化高速公路上最大的控制工程,全长约7km,最大埋深约850m。目前已开始施工。地应力是围岩变形特性的重要控制因素,也是隧道设计的重要依据。结合雪峰山隧道工程实际,运用现场钻孔水压致裂法测试及有限元数值模拟方法,研究了雪峰山隧道地应力分布规律。研究表明:本区最大主应力的方向为N50°～86°W;应力值随埋深的加大而逐渐增大;岩体最大应力分布具有明显的分带性。通过该项研究,初步查明了雪峰山隧道地应力场的基本分布规律,为隧道的设计提供了依据。

The Xuefeng mountain expressway tunnel, the largest controlling project of Shaohuai （Shaoyang-Huaihua） highway, is under construction now. The length of the tunnel is about 7km and the largest thickness to ground is about 850m. The geostress is the dominative factor for distortion characteristic of the wall rock and is important for the tunnel design. In the paper, according to the state of the tunnel, making use of in-situ testing in hydrofracturing, indoor testing of Kaiser effect of rock and finite element numeric simulation, the geostress status of of the Xuefeng Mountain expressway tunnel is studied, and its spread law was presented. The outcome of this study indicates that the direction of the maximum principal geostress is N50°-86°W,and that the quantity of the principal geosress increases gradually with the thickness of the overlay, and that the spread of the principal geostress is obvious division. The study provides the basis for the tunnel design.