Research On Construction Scheme And Support Optimization Of Karuma Underground Cavern

With the rapid development of China's infrastructure construction,the increasingly domestic background of the construction of large and super large hydropower stations in China and the rapid development of the Belt and Road,China's large-scale hydropower stations are being built abroad.This paper is based on the Karuma hydropower station in Uganda.Based on the this hygropower station and the programme of electrical transmission lines,the damage characteristics of the underground powerhouse caverns of the Karuma hydropower station is an in-depth study during the excavation process.And optimization studies of construction plans and support plans are concluded from the analysis precedent.Through the numerical analysis and simulation of the construction plan and supporting scheme of the Karuma Hydropower Station in Uganda,the optimal construction excavation sequence and support scheme are obtained,which makes the Karuma Hydropower Station in Uganda can be reduced in the optimal excavation scheme.The stress and displacement during the excavation process reduce the engineering cost and improve the engineering economy under the premise of ensuring the safety and stability of the project on the optimal support scheme.In this paper,by studying three different excavation schemes,the maximum stress and displacement in each excavation step during the three excavation schemes are compared and compared with the original excavation scheme.The research shows that the dome is in the process of excavation.The stress is the smallest and the displacement is the largest,and the arch bottom has a bulging reaction.Since the excavation of the busbar hole connects the main transformer hole and the main and auxiliary powerhouses,the ex'cavation step will greatly change the stress distribution of the underground powerhouse.After the complete excavation is finished,the clamp is completed.The maximum displacement of rock mass in the middle of the main transformer and the main and auxiliary powerhouse is the smallest,and the maximum stress of the surrounding rock is reduced by 14%compared with the original excavation scheme,and the maximum displacement of the surrounding rock is reduced from 2mm to 0.8.Mm.The maximum stress of the lining is reduced by 10 MPa,and the maximum displacement of the lining is reduced from 2.1 mm to 0.8 mm.The excavation scheme 1 first performs the first step of the main transformer opening with relatively high altitude,and then starts the excavation from the second part.The auxiliary plant,after the same excavation height,simultaneously excavated the main transformer hole and the main and auxiliary powerhouses.By studying four support schemes under the optimal excavation scheme,the diameter of the bolt on the enlarged support scheme can effectively suppress the maximum stress and maximum displacement of the surrounding rock,and agree to compare the support scheme 3 and the support scheme 4,It can be known that under the same diameter of the bolt support,the appropriate length of the lengthened anchor will also increase the safety reserve to a certain extent and reduce the stress and displacement of the surrounding rock.The maximum stress of the dome of the support scheme 1 is 13 MPa,the maximum displacement is 10 mm,the maximum stress of the surrounding rock is 25 MPa,and the maximum displacement is 1.3 mm.The support scheme 1 can ensure the safety and stability of the underground cavern.Maximize the economics of the proj ect and significantly reduce engineering costs.