发布时间:2025-01-24 05:39:08
泥浆比重任何情况下不得低于1.06 最佳保持在1.1左右,含砂率不得高于7%,粘度不得高于30s,最佳25左右,这是砂性土,粘性土有点不一样,规范的话去看地下铁道施工规范
pcb四层板可不可以把元器件的电源和地 通过过孔直接连到电源层和底层而不在顶层和底层画电源线
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