Mechanism Of Grouting Reinforcing For Shield Tunneling Of Kunming Metro Line 3 In Cumolosol Layer

Kunming Rail Transit Line 3 is the primary line of east-west direction that cross through the Kunming city proper.The rail line starts at the West Mountain Park,along Chunyu Road,West Renmin Road,West Dongfeng Road,East Dongfeng Road to Taiping Road and ends at Eastern Passenger Terminal in the east of the main urban area.The total length of Line 3is 22.95 km.Shield construction is used in the main range.The total investment is about 9.8billion.The continuous improvement of shield tunneling method on subway construction technology result in a stronger degree of mechanization and a better adaptability to the strata,leading to a wide adoption of it.The high-density of public facilities,heavy-traffic,and surface tunneling construction in urban areas has seriously interference with city lives.Especially in city center,it is difficult to achieve tunneling by open cut method if there is a deep-buried tunnel with complexion geological conditions.However,the shield tunneling method has obvious advantages in the construction of various types of tunnels such as underground railways,sewers and drainage,power communication,and municipal facilities,etc.But,shield technology and parameter control in cumulosol layer are not mature.The cumulosol in Kunming area has a wild distribution with extremely poor physical properties in low volumetric weight,high water content,large porosity ratio,strong compressibility,low strength,and slow consolidation.Kunming locates in the Dian Lake drainage area,south to the Dian Lake and surrounded by mountains on three sides.With the accelerating development of urban construction and economy,it is inevitable that the subway construction project in cumulosol area has been the process of urbanization of Kunming.During the construction process of urban shield tunneling,one of an important engineering problems is grounds settlement which not only affects the safety of tunnels but also the operation of buildings surrounding directly.Generation zone compression modulus is the vital parameter for controlling grounds settlement,particularly the shield tunneling in soft soil layers.The mixing ratio between grouting materials and soil in generation zone,and the curing time after grouting is significant factors that immediate impact the compression modulus.This paper bases on the shield tunneling project on cumulosol layer in the Shiju section of Kunming metro Line 3,and the comprssive modulus experiments under different mixing ratios and curing conditions between grouting material and cumulosol.To explore of the reasonable proportion between the grouting materials and soil in cumulosol layer,and to propose when the expected compression modulus in generation zone can be reached after grouting,and to simulate the test results by using numerical simulation software Flac 3D for observing changes that different compression modulus in generation zone affect on ground settlement,providing reference for metro shield tunneling construction in cumulosol areas.