在日本未采用“新奥法”施工前,用的是美国式的施工方法,它是用支撑的强度来作为围岩分类的基础。分类的出发点是围岩的松弛状态,围岩的重量就靠支撑,所以支撑的尺寸非常大,间距非常小,所以在日本未引进“新奥法”以前,都是由支撑来决定围岩的强度,这种构思是基于变形越大,支撑的尺寸和密度也越大,因而空 Before Japan adopted the “New Austrian law” construction method, it used an American-style construction method that used the strength of the support as a basis for classification of the surrounding rock. The starting point of the classification is the relaxed state of the surrounding rock. The weight of the surrounding rock depends on the support. Therefore, the support is very large in size and the spacing is very small. Therefore, until Japan introduced the “New Austrian law,” it was determined by the support The strength of the rock, which is based on the idea that the larger the deformation, the larger the size and density of the support,