| Pile foundation engineering is a permanent project,which involves many subject projects,the factors are complex and the construction technology is difficult.A little carelessness in the construction project will endanger the safety of the building itself,causing major personnel and economic losses.Therefore,it is an important subject of practical significance and scientific research value to select the type of pile foundation to ensure the safety of the construction of the project,to detect the pile in the construction process and to maximize the comprehensive benefits.Based on the project of Lijing Bay,selecting the pile foundation of 10# and 11# building on the basis of the common pile foundation type,determines the design scheme,then tests the pile foundation in the construction process,and finally analyzes the cause of the accident according to the result of the test,and deals with the accident.The main work done and the results obtained are as follows:(1)The common type of pile foundation is analyzed and studied.According to the geological conditions of the project,the advantages and disadvantages of the pile type and the actual situation of the project,the punching(drilling)hole filling pile is selected and the bearing layer is a strong weathered granite.(2)Based on the Lijing Bay project,the single pile vertical compression static load test and acoustic transmission method are used to test the pile foundation of the 10# and 11# building of the project through a variety of testing methods.The test results all meet the design requirements;the pile foundation of the 10# and 11# buildings is tested by the low strain method according to 100%.The test results show that the 10# building appears.III and IV 55 of the unqualified piles accounted for 67.9%,and the third floor of 11# building and 55 of the unqualified piles accounted for 88.7%.(3)Test the core of 24 and 11# buildings in 10# building;the test results show that the defects of the low strain method are accurately determined and the position of the defect is broken in varying degrees.The main reason for the fracture of the pile is that the pile circumference caused by the displacement of the pile increases the lateral force of the pile,and the shear failure of the pile body is carried out.(4)To explore the classification of pile quality accidents and treatment methods of common accidents on common soft soil foundation.(5)The accident analysis of unqualified piles in the pile foundation of 10# and 11# buildings,the cause of the broken pile: the external cause of the 11# building is due to the use of large equipment for the rapid excavation of the foundation pit,the large height difference surface in the excavation site,and the heavy rain caused the excavation of the foundation pit to soak in the water for a long time;the external cause of the 10# building is due to Due to the increasing load of the reinforcing bar in the east side of the foundation pit,the inner excavation speed of the excavation is too fast;the internal cause is the thick silt thickness in the soil of the 10# building and the 11# building,the change of the mechanical properties of the silt soil,the creep or displacement of the unstable silt soil soil,and the shear fracture of the pile.(6)There are III and IV unqualified piles on the pile foundation of 10# and 11# buildings.The construction party organizations and experts and various construction units have dealt with the accident analysis and treatment of the 10# and 11# buildings,and put forward the treatment scheme: the high pressure grouting treatment of the 24 and 11# buildings of the 10# building is carried out by high pressure grouting,and the vertical compression bearing capacity of the pile single pile after treatment is used at 50% and the pile top level.The pile and pile IV above 300 mm are not used as engineering piles. |
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