秦岭越岭长隧道地区构造应力场特征分析

Analysis of Features of Regional Tectonic Stress Field in the Area of the Long-tunnel Through Qinling Mountain

利用微断层研究方法,由定性到半定量,由点到面地分析了西安—南京线越岭长隧道地区的区域构造应力场演化、性质、方向和构造应力作用方式,为越岭长隧道方案比选提供了应力场依据。根据微构造法计算结果,本区新构造及现代构造应力场经历了:松弛期应力场、NW向挤压NE向拉伸的构造应力期、NE向挤压NW向拉伸的构造应力期。自第三纪以来,区域应力状态从总体上讲,是以垂直方向抬升、水平方向拉伸为主,现代构造应力场的性质是NE—SW或NEE—SWW向的挤压。从晚近地质时期到现代主压应力方向为NE向,σ1优势方位为NNE—NE向。自第二期应力场以来,主应力作用方式都是水平挤压或水平拉伸。

With the micro-fault research methodology, the paper studies the characteristics, evolution and direction of the regional tectonic stress field, and acting method of the tectonic stress from a point to an area and from qualitative to semi-quantitative of the long tunnel on the Xi'an-Nanjing railway line, and provides the stress field basis for selecting railway lines. Through the micro-fault calculation, the new tectonic and modern tectonic stress field have experienced a period of relaxation stress field, the tectonic stress period of extrusion in the direction of NW, the extension in the direction of NE, the tectonic stress period of extrusion in the direction of NE and extension in the direction of NW. Since the Tertiary, the regional stress status showed a rise in the vertical and extension in the horizontal. The feature of the modern tectonic stress field shows the extrusion in the direction of NE-SW or NEE-SWW. From the later and near geological period to the modern geological period, the direction of modern main press stress was in the direction of NE, the ruling direction is NNE-NE. Since the second period stress field, the main stress action methodology was all horizontal extrusion or extension.