Identification Method of Soft Soil Disaster Due to Ground Improvement Construction

The Yangtze River floodplain sedimentary soft soil is the fluvial facies sediment since the quaternary period, and it is mainly composed of silty clay, silty fine sand and fine sand, which is characterized by high compressibility, low strength and easy liquefaction. Thixotropic phenomenon is caused by the improvement construction of soft soil foundation in the Yangtze River floodplain, and leads to the disaster of the soft soil foundation. The disaster phenomenon of the Yangtze River floodplain soft soil foundation is summarized as caused by the ground improvement construction. In-site monitoring of earth pressure, pore water pressure and horizontal soil displacement of soft soil are monitored in the construction of ground improvement in Yangtze River floodplain soft soil foundation. The disturbance of Yangtze River floodplain soft soil is evaluated and the disaster criterion of Yangtze River floodplain soft soil foundation is put forward during the construction of ground improvement. The soft soil disaster caused by the construction disturbance of cement deep mixing column is characterized by the sinking of the column top. The maximum sinking amount of the column top reaches 70cm, accompanied by a large amount of fine sand pouring out. In the process of drilling core sampling of cement deep mixing column, water spray and slurry appear in the position of adjacent cement deep mixing column, the core extraction rate of cement mixing column is less than 60%, and the quality of deep mixing column is poor. The excess pore water pressure measured at the disaster position of soft soil is greater than the soil pressure.