Improvement of Shallow Soil Using Electric Heating Equipment

Abstract

This paper is to develop the method of surface soil improvement by electric heating equipment. For this purpose, the electric heating systems were invented to apply to the in-situ soil. Iaboratory tests were done to study the behaviors of sea clays by eletric heating. In lab tests, two different heating temperatures, 70℃ and 110℃, were applied to the saturated clays to examine the relationship between evaporation and compaction. In addition, trafficability was analyzed to the heated by applying cone penetrometer to the heated clays Furthermore, in-situ tests were conducted to analyze the range of soil improvement and strength variations. The temperature changes in field were measured and they were compared with those of the commercial program (Temp/W). Also, the bearing capacities of electrically heated field were tested by PBT (plate bearing test). Several conclusions were derived from the results of the numerical analysis and tests (lab and field). The improvement ranges and strength variations of electrically heated soil depended on the heating temperature and time. If the heating temperature is more than 100℃ evaporating the ground water, the bearing capacity and settlement increased rapidly. The bearing capacities of in-situ soil increased more than 3 times, and heated soil emitted a lot of vapors. The soil around electric heater was sintered completely, and its range was almost 20 cm.

A Study on Heat-Transfer Characteristics by a Ground-Heating Method

“…In both methods, marine clays such as tidal flats have a very small permeability, so that excess pore water pressure is generated by the preloading of embankment, and it is drained by the vertical drainage of sand. However, because this method requires a large amount of sand, deforestation and land degradation are serious [1]. Furthermore, because the permeability of the clay is very small, the consolidation of clay takes about five to 10 years to complete [2].…”

“…In recent years, Park, Im, Shin and Han [1] proposed a ground-heating method in which fossil fuel use was improved with the electric heating pipe. The electric heating pipe converts the electric energy into thermal energy by the electric-resistance method, and is applied to the improvement of the strength of the soft ground.…”

“…Furthermore, the operation of this system requires highly skilled engineers. Finally, the cost of fossil fuels is high, and the economy is low [1].…”

A Study on the Improvement Effect and Field Applicability of the Deep Soft Ground by Ground Heating Method

“…Excess pore water pressure is generated by the preloading of the embankment in cases of low permeability soils. The pore water excess is drained by vertical prefabricated drains [2,[15][16][17]. However, permeability soils.…”

“…However, permeability soils. The pore water excess is drained by vertical prefabricated drains [2,[15][16][17]. However, due to large settlements and/or filter clogging, the vertical prefabricated drain is blocked and excess pore water is not drained [18,19].…”