Effect Of Tail Void Grouting On Ground Settlements In A Interval Period Of Subway

With the unprecedented development of the underground space, shield method iswidely used in the city subway construction. The tail void grouting is a significant step ofshield tunnel, which obviously affects the security of shield construction. In order to studythe effect of grouting pressure and grouting volume on the group settlements, numericalmodels are established based on the software of Flac3D.The advantages and disadvantages of different tail void grouting were compared andthe calculation theory and method of grouting parameters were generalized includingquantity and pressure of pour slurry. Bases on Jiang-Ji tunneling of the first project ofWuhan Metro Line No.2, grouting pressure is classified into stress little release, stressrelief50%,75%of stress relief and stress release completely in four states. And then fournumerical models were established. Thickness of quantified layer was defined from10cmto40cm and numerical models were established. At last the result compares to the actualdata.The conclusion shows:(1) With the value of the stress release increasing, the surfacesubsidence increases. Grouting volume increases with increasing thickness of quantifiedlayer. And growth rate of four cases is liner;(2) Both grouting pressure and groutingvolume relatively effect on ground settlement. But the influence of the tunnel surfacesettlement on the edge is very small. The effect of grouting volume on ground settlementsis more obvious than grouting pressure;(3) Comparing to the actual monitoring data andnumerical simulation data, it is the suggestion that stress release can be keep nearly50%to control grouting pressures. And the suitable grouting thickness is35m; In order todecrease ground settlements, it is more obvious to control grouting volume than groutingpressure. The conclusion has reference meaning for similar conditions.