Using intelligent inclined borehole optical imager to interpret geometrical characteristics of fractures in crystalline rock mass
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摘要: 钻孔电视成像技术由于其高精度数字记录成像的特点，克服了工程钻探过程中岩芯不连续、裂隙几何要素信息丢失等问题，在国内外工程勘察中得到了广泛的应用。但目前钻孔成像解译大都以竖直孔为主，倾斜孔成像解译应用较少。结合某地区地下水封洞库项目中的斜孔电视成像工作，介绍了斜孔成像裂隙的解译方法，通过空间坐标转换将结构面的视产状转换成真产状，并在此基础上针对该地区地下水幕系统和洞室所在位置深度范围内的裂隙发育情况分三部分对深部花岗岩结晶岩体裂隙几何要素进行了统计分析，揭示了相应的裂隙发育产状变化特征和垂向变化特征，结果表明该地区主要发育NE 20°~40°和NW 20°~40°优势构造成因裂隙，裂隙发育数量呈现先减小后逐渐增大并维持较稳定数量的变化趋势。以此可为评价洞库围岩稳定性、水幕系统水封效果等提供了可靠的数据支持。Abstract: With the characteristic of high digital record and by overcoming a series of problems in the process of engineering drilling, such as discontinuity in drilled cores, missing information of fracture geometric elements and so on, the technology of intelligent borehole optical imager is widely used in engineering investigations all over the world. However, at present the technology is mostly used for vertical boreholes, less for inclined ones. Combined with the results of the inclined boreholes applied with the technology of intelligent borehole optical imager, which come from the project on gas storage in underground caverns with groundwater in a certain region, this paper introduces the interpretation approach of the fractures derived from the results of inclined boreholes recorded by means of intelligent borehole optical imager. The approach can convert the apparent occurrence of discontinuities to the real occurrence with the method of spatial coordinate transformation. A statistical analysis on the geometric elements of the fractures in deep crystalline rock mass under the condition of the development of fractures in the vicinity of the storage caverns and water curtain system is made. The characteristics in the occurrence and in the vertical direction of the development in fractures are examined. The results indicate that fractures originated from the tectonic movement develop in a superior position with a strike of NE20°~40° and NW20°~40°, the trend in the quantity of the fractures is that decreases at first, then increases gradually and at last stays at a stable state. The resluts can provide reliable data for evaluating the stability of the surrounding rock of caverns and the effect of the water curtain system that prevents gas leakage.
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