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The use of electric heating when not freezing a ditch at the entrance to the tunnel of an expressway

Preventing freezing of tunnel inlet drainage in cold regions is an important issue to be paid attention to when building tunnels in cold regions. The installation of a self-regulating electric heating system at the bottom of the mouth on both sides is an important measure to prevent the mouth from freezing at the entrance to the cave.

Mar 18,2023

For the Fushui Tunnel project located in the Alpine region, usually due to the low daytime temperature in the geographic location of the tunnel and the high wind speed at the tunnel entrance, subject to extreme winter weather conditions, drainage ditches on both sides of the tunnel entrance can freeze. As a result, seeping water in the tunnel cannot be released unhindered and eventually overflows through the ditch, enters the ballast layer and forms ice, affecting traffic safety and creating huge safety threats. Therefore, the prevention of drainage and freezing of ditches at the entrance to tunnels in the highlands is an important issue that requires attention in the construction of tunnels in the highlands.

In our country, the following types of drainage ditches are mainly used at the entrance section of the tunnel in the highland region: deep buried in the center, thermal insulation, warming, as well as a combination of thermal insulation and warming ditches. As a rule, after the completion of the tunnel, there are two remedial measures. The details are as follows:

After the ice in the cuvette is cleaned, the concrete at the bottom of the ditch will be removed with a pickaxe within 50 m of the mouth of the ditch on both sides, the slope at the bottom of the ditch will be heated, and will be connected to the inspection well on the hole through the thermal insulation pipe at the hole; The construction team installed a self-regulating non-freezing electric heating system at the bottom of the ditch on both sides and laid a heating cable on each side of the ditch, and the installation range was within 1 km from the entrance to the tunnel.

The key to non-freezing tunnels in alpine regions is good drainage work The isolation part of the ditch, especially the part of the tunnel entrance, should be well insulated to avoid freezing and expansion of the layout causing serious illness. When installing a thermal insulation ditch, you should pay attention to the moisture-proof treatment of the cold insulation material, t. The ditch should be weakened as much as possible in terms of design to reduce convection caused by convection heat losses.

Reliable measures should be put in place in tunnel ditches in the highlands to prevent flowing water from freezing. Taking into account comprehensively, a single insulation of the gutters on both sides cannot guarantee the occurrence of ice in the winter. To prevent cold and keep warm, a combination of passive protection from cold and active insulation in thermal insulation ditches is used. Method, Which consists in installing an electric heating system in trenches in which insulation measures are taken, can effectively solve the problem of freezing dains at the entrance to the cave.

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