Как обещал...
Единственное вся инфа на "буржуйском"...
тема называется FTB (Fluidized Thermal Backfill)...
если не сильно вдаваться в подробности - подготавливается постель для кабеля, 1 часть цемента м250 на 14 частей песка...
Данная смесь после "спекания":
1) Обеспечивает какую-никакую механическую защиту КЛ (в дополнение к жб плитам или лотка)
2) Обеспечивает хорошие и постоянные характеристики по тепловому сопротивлению
3) В случае необходимости (ремонт КЛ) - легко удаляется подручными средствами
«Underground Cables Need a Proper Burial
Unless you lay your cables to rest properly, they may come back to haunt you. Here's a brief example. A wind-generating farm was installed with underground cables tied directly to a main feeder cable. Unfortunately, the cables were simply placed in a trench using native soil backfill with minimal soil compaction. Ampacity calculations were performed using typical soil values, but thermal properties were not measured. Since wind turbines operate almost continuously, the feeder cable often ran at maximum capacity. The heat generated from the feeder cable dried out the surrounding soil completely. Because the native soil was poorly compacted fine silt, it acted like an insulating blanket and the cable failed prematurely.
»
«Fluidized Thermal Backfills
Over the past 10 to 15 years, we've seen great acceptance of fluidized thermal backfills (FTB™), which are formulated to meet thermal resistivity, thermal stability, strength and flow criteria. This free-flowing, controlled-density fill is ideal for hard-to-access areas, such as narrow trenches, small diameter tunnels or areas congested with many underground services — basically where mechanical compaction is not feasible or practical. While the material cost of FTB may be higher, it should be considered for general usage because of its assured quality and quick installation, thus speeding up construction and decreasing overall costs, which are important factors when working in busy city streets.»
«FTB is a slurry backfill consisting of medium aggregate, sand, a small amount of cement, water and a fluidizing agent. FTBs can be formulated using locally available aggregates. The component proportions are chosen by laboratory testing of trial mixes to minimize thermal resistivity and maximize flow without segregating the components.
»
«By using a sufficiently large thermal backfill envelope, the heat flux through the native soil will be quite low; therefore, the native soil will not dry out, and the stability of the native soil is not a concern.»
Есть буржуйское ТЭО по применению таких смесей...но все в клятых долярах...
и файл весит 13 метров...
