基于视电阻率法测试技术的隧道围岩松动圈测定

Measurement of Loose Zone of Tunnel Surrounding Rock Based on Apparent Resistivity Method

隧道围岩松动圈厚度大小是评价围岩稳定性和设计合理支护方案的重要参数和依据,如何快速且无损地探测出围岩松动圈范围至关重要.通过采用瞬变电磁仪视电阻率测试方法,对试验隧道围岩松动圈进行了探测,结果表明:松动圈厚度在1.68~2.25 m,属于大松动圈.同时,结合现场地质状况,以松动圈厚度大小为依据,判定围岩类别为Ⅳ~Ⅴ类.最后,以松动圈厚度大小和围岩类别为依据,设计支护方案,经后期监测,隧道变形小,验证了该方案合理可靠.

The thickness of surrounding rock loose zone of tunnel is an important parameter and basis to evaluate the stability of surrounding rock and make a reasonable support scheme.How to detect the range of surrounding rock loose zone quickly and nondestructively is very important.By using the test method of apparent resistivity of transient electromagnetic instrument,the loose zone of surrounding rock of the test tunnel is detected.Results show that the thickness of the loose zone is between 1.68~2.25 m,which belongs to large loose zone.At the same time,combined with the site geological conditions and based on the thickness of the loose zone,the surrounding rock is determined as classⅣ~Ⅴ.Finally,based on the thickness of loose zone and the category of surrounding rock,the support scheme is designed.After later monitoring,the tunnel deformation is small,and the scheme is reasonable and reliable.