Abstract: Transmission line in Sichuan mountainous area always layout in steep slope, where Gravel soil and bedrock dual structure formation are common in the region. As such, proportional coefficient m of ground horizontal resistance coefficient is the problems to be settled urgently in the design of transmission line tower pile foundation in the steep slope. m value is obtained by the static horizontal loading test of single pile. Three methods including field experiment, indoor model test, and numerical simulation are used to investigate the changing rules, influence factors and accessor methods of the m value. The results indicate m value of slope site decreases linearly with the increase of slope, and the decrease of m in gravel soil is greater than in the gravel soil-bedrock foundation. The most influencing factors on m value are ground slope, soil compactness, pile length and pile diameter. The proposed prediction formula considers impact factors of m value of the gravel soil, gravel soil and bedrock in slope site, and provides the correction coefficient.

Key words: slope site, gravelly soil, proportional coefficient of ground horizontal resistance coefficient m value, horizontal load tests of single pile