Soil ionisation has an important influence on impulse characteristics of grounding conductor. This paper introduced improvements to an existing soil ionisation model considering the influence of electric field on the change of soil resistivity, while soil resistivity is not directly dependent on soil electric field. The validity of improved soil ionisation model was verified by surge response of vertical conductor in uniform soil and horizontally stratified soil. Furthermore, the impulse experiment was carried out on horizontal conductor in soil with finite volumes. Based on experimental configuration, the corresponding calculation model was built, and calculated results were in good agreement with experimental results.

Deep well grounding electrodes (DWGE) have small occupied areas. The number of sub-ground electrodes is less than that of traditional vertical grounding electrodes. Thus, the former has a favorable development prospect. However, given that the active part of a DWGE is buried in the deep earth, DWGE faces more complex gas exhaust problem than shallow-buried grounding electrodes. To research the gas evolution characteristics of DWGE, a U-shaped gas evolution experimental platform that can collect anode and cathode gases separately is designed. Carbon steel material is used as the electrode, and experiments have been conducted on water and saturated coke on the basis of the designed platform and a 30-m DWGE test. The results show that the operating environment and mode (anodic/cathodic) affect gas evolution. When inside water, only the reaction of Fe dissolution occurs at the anode, and Fe is transformed into Fe2+ while hydrogen evolution and oxygen consumption reactions occur simultaneously at the cathode. When in saturated coke, the gas production at the cathode increases with ampere-hours, thereby changing the contact resistance between the electrode and the coke and forming a "bubble resistance", then leading to a gas block. The test result of a 30 m well at 100 A further verifies the experimental results of the designed platform and confirms that a vent pipe plays a role in practical use.