Sichuan power transmission lines pass through the mountain area with a wide distribution of gravel soil.The gravel soil is a special rock and soil between the rock body and the soil body. There are different types of the gravel soil classification. For the gravel soil foundation pile under horizontal with different stone content, the horizontal bearing characteristics have a big difference. The current standards give a quite wide range of theproportional coefficient m of ground horizontal resistance coefficient. In practical application, we evaluate the m value too random. At present, there are some researches on the soil properties of gravel soil with different stone content, however, there are few researches on the characteristics of pile-soil horizontal interaction for gravelly soils with different stone content. Therefore, evaluating the characteristics of pile-soil horizontal interaction and m value on the gravel soil foundation under different stone content is a task to be resolved for the design of transmission tower pile foundation. In this paper, single pile static lateral loading tests are conducted in State Key Laboratory of Geohazard Prevention and Geoenvironment Protection of Chengdu University of Technology. We obtained three gravel soil with different stone content by conducting sizing test. We carried out three sets of physical simulation tests with different stone contents respectively, and obtained the mechanical parameters of gravelly soil with different stone contents. Then we got the effects of the displacement of pile top, the internal force of the pile, the proportional coefficient m of ground horizontal resistance coefficient with different stone content. We got the variation tendency of the m value with different stone contents. According to comparative analysis, we got the experiment characteristics and laws, and studied the bending moment value of pile curve, shear force curve, soil pressure curve on the pile side, and the variation tendency of the m value with different stone contents. The results indicate that pile bending moment first increases and then decreases from pile top to pile bottom. As the stone content of the gravel soil foundation grows, the maximum bending moment value of pile grows nonlinearity. The maximum bending moment value is buried approximately at 0.3 meter depth location of the section. At the condition of high stone content, bending stiffness can be properly increased at the position of the section at design time. As horizontal force increases, soil pressure on the pile is nonlinearly increase, too. As the stone content of the gravel soil foundation grows, the ground horizontal resistance increases, the position of zero of soil pressure on the pile side can also improve. This is due to the improvement of the horizontal resistance of the gravel soil and the simultaneous increase of the earth pressure before and after the pile. The stone content increase every 10％, the m value would also increase about 1.15 ～ 1.40 times. This research fill the application blank which does not address the different stone contents of the gravel soil affecting m value. It can also be used as a reference of the proportional coefficient m of ground horizontal resistance coefficient.%四川输电线路经过的山区场地中,碎石土地基分布普遍,而碎石土是一种介于岩石和土体之间特殊的岩土体,水平受荷碎石土桩基础在不同含石量下水平承载特性具有较大的差异,现行规范给出的地基水平抗力系数的比例系数m值取值范围较为宽泛.研究碎石土地基在不同含石量下桩-土水平作用特性与m值取值是输电线路塔桩基设计中有待解决的问题.通过室内单桩水平静载试验,得到了不同含石量的碎石土地基对桩顶位移、桩身内力、地基水平抗力系数的比例系数m值的影响,以及不同含石量下m值的变化趋势.对比分析得到试验特征规律,研究桩身弯矩、剪力曲线与桩侧土压力曲线,不同含石量条件的m值变化趋势.结果表明:随着碎石土地基含石量提高,桩身最大弯矩值呈非线性增大,且最大弯矩值约在埋深0.3 m截面位置处;碎石土含石量的提高,地基土水平抗力会有所增大,桩侧土压力零点位置也会有所提高;m值随着含石量的提高而增大.含石量每提高10％,m值约增大1.15～1.40倍,该项研究可作为地基水平抗力系数的比例系数m值取值的一个参考.
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