In-situ Experimental Study Of Soil Disturbance And Horizontal Displacement Characteristics Caused By Shield Tunnelling

With the development of the city,the land resource is becoming increasingly scarce,the development and utilization of underground space has become a common practice.Large diameter shield tunnel has been widely used for its advantages of large space and small occupied land.The greater the diameter of the shield,the more complex the soil of the excavation face,the greater the difficulty of construction and the greater disturbance to the surrounding soil.Therefore,it is necessary to study the disturbance of the surrounding soil in the large diameter shield tunnel.Based on the large diameter slurry shield tunnel of the south extension section of Guangzhou metro line 4,the disturbance around the shield tunnel construction is studied with the field measurement.The specific work and main achievements are as follows:(1)Focusing on the in-situ tests,we design a field test scheme including the horizontal displacement of deep soil closely and densely,which obtain the characteristics of horizontal and vertical displacement of the surrounding soil.(2)By introducing the incremental analysis method and combining with the field measured data,we found the law of the lateral and axial disturbance of the soil around the tunnel.On this basis,we put forward the method for analysis of the maximum increment,which obtains the distribution of lateral disturbance of the surrounding soil is a V shape along longitudinal axis.And with comparison of other in-situ test data,we further validate the law.(3)Integrated all test data,four different deformation modes of surrounding soil caused by shield tunneling are summarized and the transformation between them is discussed.And further analysis is carried out on the mode of “lateral-heave”,one of the four patterns.It is found that the grouting parameters which include grouting pressure and volume are the key.Suggestions about the surface settlement monitoring and optimizing the shield tail grouting control are put forward in order to prevent the “lateral-heave”.