Key work and methods for investigation of karst along pipeline route

The karst survey along pipeline route is different from that of normal pipeline route, its key jobs are mainly in the phase of detailed reconnaissance, and follows the working principles of "from surface to point, surface before underground, qualitative before quantitative, limited before normal and loose before intensive". Survey methods such as engineering geological surveying, drilling, geophysical prospecting, hydrogeology experiments and laboratory experiments are adopted to analyze and evaluate the distribution of the karst along the pipeline and engineering geological conditions, the position, scale, morphology, buried depth and stability of karst caves and characters of karst accumulations (red clay, soft soil) which have effect on the safety of pipeline route, and characteristics of ground water, the distribution of karst collapse areas along the pipeline route and engineering hazards are pointed out, which can be taken as a foundation in the design and construction in order to prevent and reduce the damage of karst collapse to pipeline.