基于钻孔成像技术的隧道围岩裂隙分析

Analysis of Fissures in Tunnel Surrounding Rock Based on Borehole Imaging Technology

文章利用钻孔成像技术,研究公路隧道围岩裂隙发育规律和钻孔成像技术的优劣。以廷心隧道原位改扩建为工程背景,通过钻孔成像技术与其他方法的对比分析,发现隧道洞身区段的围岩主要发育两组主控节理,岩层主要为第四系坡积层(Q_(dl) )、三叠系百逢组(T_(2)b)砂岩,属较软岩,裂隙较发育、裂隙面多起伏,岩体完整性较差,节理裂隙以共轭的中倾角发育为主;相较于钻孔取芯技术,钻孔成像技术成功率高,且具有获取信息丰富、精确度高、简单易操作等优点,但当遇到钻孔中泥质或岩粉污染孔壁时,钻孔成像技术的效果也将削弱。

In this paper,the borehole imaging technology wa.s adopted to study fissure development law in surrounding rock of highway tunnel and the advantages and disadvantages of the borehole imaging technology.Based on the engineering background of the in-situ reconstruction and expansion of Tingxin Tunnel,the comparative analysis was carried out for borehole imaging technology and other methods to find out that two groups of main control joints are mainly developed in the surrounding rock of the tunnel body and the rock stratum is mainly composed of Quaternary deluvium(Q_(dl))and Triassic Baifeng formation(T_(2)b)sandstone,which are relatively soft and propitious to development of fissures with undulating planes and poor rock integrity.The joint fissures were mainly developed in conjugate medium dip angle.It was also found that the borehole imaging technology has a higher success rate than core drilling technology and has such advantages as rich information,high accuracy,simple and easy operation,etc.However,the effect of borehole imaging technology might also be weakened when borehole walls are contaminated by mud or rock powder.