Research On Rock Loosen Zone Self-Bearing System In Large Underground Water-sealed Storage Caverns

Long-term stability of surrounding rock problem and water-sealed safety problem in large underground water-sealed storage caverns were the main point in constructing.The problems of surrounding rock stability in large underground water-sealed storage cavern were as follows: large cross section,long span tunnels crossover densely,tunnel unlined,no structural backfill,oil-gas-water existing at same time and no repair condition.The problem of water-sealed safety problems were as follows: water protect constructing,chemical grouting avoid,blasting wave destroy the grouting material,rock bolt penetrated the integral rock could lead to new leakage,caverns in seabed could rust the bars.This paper proposed a whole rock loosen zone self-bearing system based on the features of large underground water-sealed storage caverns which aims at enhancing the safety of the caverns.By calculating the stress concentration in the rock mass after excavation and the damage zone after multi-excavation,it was shown that the current support pattern was hard to establish enough strength in the damage zone and it had risk to break the integral rock.If the rock mass was worse than IV1,it's necessary to optimize the tunnel section.And if the rock mass was better than III2 but had fault in it,it's better to enhance the broken zone.Therefore,a method by grouting to enhance the loosen zone was invented and its possibility was proved.A digital module was developed under the platform of lifecycle integration system which was used for forecasting the fault in the front of the excavating face.By optimizing the system database,mass data was able to transfer fastly and the forecasting result was become precisely.A new grouting material was invented by plenty of experiments which was able to establish strength in a short time.The laws were detected that material accelerated hydrating and descended compressive strength under pressure circulation.Therefore,the traditional circulating grouting method was abandoned and a new grouting method was improved.Dynamic drilling method and derive grouting method were invented which aimed at injecting the material into the rock microfissure.At the same time,enhance grouting machine was invented which improved the grouting efficiency.The paper's concept and results were all derived from the contribution period of the fist large underground water-sealed cavern in China and the largest one in the world.Some of the technologies were already applied in the following construction.