Digging up the ground is activity that is a must for new constructions, whether it be a garden shed or an industrial building. Most of this work is for foundations, but you may even need to dig trenches for installing or uncovering utilities. During summer or warmer days this is not a problem if you have the right equipment and operators, but in severe winters, the ground can get frozen, making it very difficult to dig, even with hydraulic equipment, and almost impossible to do it manually. The sane thing would be to do it wait till the weather is kinder, and the warmth in the air leads to the ground thawing naturally and returning to its old state. But this may at times not be possible because of tight schedules, emergencies like breakdowns in utilities, and other reasons like digging graves. How do you go about thawing the ground to allow you to continue with your construction or other activity?
The ground always has more heat at the bottom, and it is only when it is continuously cold that the frost line goes lower and leads to frozen ground that becomes difficult to dig. There are many technological innovations used for the thawing of ground, and as you would surmise all of them require heat. Even with the heat coming up from inside ground, the real thawing is quicker if its from top.
Equipment used for ground thawing can be sturdy blankets that are heated by the electrical elements embedded in them. Temperatures that will be generated in these blankets will be 60°F more than the outside ambient temperature. You can always add extra insulation over the blankets to get an increase of temperature by another 10°or 15°. Some blankets have a capability to increase the temperature above ambient by 150, and are used by landscapers and in cemeteries.
Another form of thawing ground is by using hydronic heating, a technology that uses heated liquids, or water to produce the heat needed for thawing. The equipment used to defrost ground consists of a boiler that heats the fluid, pumps to circulate the heated liquids and send them through flexible hoses laid out over the area that needs to be thawed. The pipes have a spacing of 20-30 centimetres between them. The circuit of pipes is a closed one, with the fluids going back to the boiler to get additional heat. To preserve the heat, these pipes are covered with insulation mats, so that the heat is transferred to the ground and is not lost in the surrounding environment. The heat is transferred to the moisture in the soil, whose freezing had led to the situation originally. This thawing works to a depth of 40- 80 centimetres every 24 hours, depending on the weather and severity of the ground freeze.
The equipment can be started and left unmanned till the thawing, which will take at least twenty four hours. Areas that can be thawed can be as big as 200 to 400 m2, depending on the capacity of the equipment. If you need to go deeper, the equipment will require to be reused, after the thawed ground has been excavated and removed. This equipment is in use by contractors who have tight schedules that do not permit any delays in the sequence of operations. It can be hired from plant suppliers at reasonable costs, as it is not the sort of equipment that is in the permanent armory of most contractors.
There is no need to clear the snow from the thawed ground prior to using this equipment, as snow will actually increase the thawing rate, as the snow will melt and get absorbed by the ground.