PROBLEM TO BE SOLVED: To provide means for preventing liquefaction of a ground or a cushioning material around an underground pipe at a time of earthquake, and effectively preventing damage to the underground pipe.SOLUTION: A cushioning material 4 for an underground pipe is disposed around an underground pipe 3 when the underground pipe 3 is buried, and includes sand and fine-grained soil of a particle diameter smaller than the sand for filling a gap between the sand particles. With the cushioning material 4 for an underground pipe, a mass ratio of the sand to a total mass of the sand and the fine-grained soil is between 70 and 80%. A sand particle diameter is between 0.075 and 2 mm, while a grain diameter of the fine-grained soil is 0.075 mm or less. The sand used is that with a density between 1.72 and 2.00 g/cmand a coefficient of subgrade reaction (K value) between 2,000 and 10,000 MN/m, when the water content ratio of the sand is in a range between 7.5 and 12.5%.SELECTED DRAWING: Figure 1
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机译：要解决的问题：提供一种在地震时防止地下管道周围的地面或缓冲材料液化并有效防止对地下管道的损坏的方法。解决方案：在地下管道周围放置一个缓冲材料4当地下管道3被埋入地下管道3时，地下管道3包括沙子和粒径小于沙子的细粒土壤以填充沙子颗粒之间的间隙。利用用于地下管道的缓冲材料4，沙子与沙子和细粒土壤的总质量的质量比在70％至80％之间。砂的粒径在0.075mm至2mm之间，而细粒土壤的粒径在0.075mm以下。当沙子的含水率在7.5到12.5％的范围内时，所使用的沙子是密度在1.72至2.00 g / cm之间并且路基反应系数（K值）在2,000至10,000 MN / m之间的沙子。选定的图纸：图1
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