求翻译：钢管使用条件分为架空敷设及埋地敷设等几种方式。架空及地沟敷设在管道安装到位后现场保温，埋地敷设采用直埋式预制保温管埋地，周围回填细砂。是什么意思？

Steel pipe using conditions are divided into overhead such as laying and burying ground in several ways. Overhead and trench laying in conduit in place on-site after insulation, precast buried laying directly buried insulating pipe buried, surrounded by sand backfill.