Geotechnical monitoring on the stability of a pilot underground crude-oil storage facility during the construction phase in China

• A monitoring scheme for stability of underground oil storage caverns in the construction phase.
• The results of geotechnical monitoring on a pilot storage caverns in China were presented.
• The spatial and time dependent effects of the excavation face were analyzed.
• The effect of the geological conditions on rock mass deformation and rockbolt stress was analyzed.
• This study compared the data from the pilot caverns with those from underground powerhouse caverns of hydropower stations.

Geotechnical monitoring is one of the important means for the control of safety of underground structure in both construction and operation phase. In this study, geotechnical monitoring on the stability was performed on a pilot underground crude-oil storage facility during the construction phase in China. Considering the engineering characteristics and geological conditions of the caverns, this study proposed a monitoring scheme for the stability of the underground oil storage caverns during the construction phase. This study systematically summarizes the results of geotechnical monitoring on a pilot underground water-sealed crude-oil storage caverns during construction phase in China. The monitoring results of the deformation of the surrounding rock showed that the convergence of the surrounding rocks, the crown settlement and the internal displacement of the caverns were within the ranges of 4–8 mm, 3–6 mm and 4–8 mm, respectively. The monitoring results of the stress on rockbolts show that the stresses were mostly less than 50 MPa. The spatial and time dependent effects of the excavation face and the effect of the geological conditions on the rock mass deformation and on the rockbolt stress were analyzed using the geotechnical monitoring data. This study compared the data from the pilot underground crude-oil storage caverns with those from underground powerhouse caverns of hydropower stations. The comparison showed that the stability of the underground pilot crude-oil storage caverns during the construction phase was relatively superior to that of the underground powerhouse caverns of the hydropower stations due to the relatively good quality of the rock masses.