After the shield tail is separated from the segment, an annular columnar gap is formed between the soil and the segment of the shield tunnel. Grouting behind the shield tail gap is an important means to control the stress release and formation deformation. The slurry injected into the soil will cause certain pressure on the segment, easily leading to dislocation and cracking of the segment. Based on the principle of hemispherical diffusion, considering the inhomogeneity of slurry in spatial distribution, the temporal and spatial distribution of consistency of power-law slurry is studied, and the calculation formula of slurry pressure distribution and slurry pressure on the segment are obtained. Through case analysis, the calculation results of whether the spatial distribution of slurry consistency is considered are compared. At the same diffusion radius, when the spatial distribution of slurry consistency is considered, the slurry pressure is large. When the spatial distribution of slurry consistency is considered, the force calculation result of slurry acting on the segment is twice that without consideration. The calculation result considering the spatial distribution of slurry consistency is safe for engineering. It is suggested that the calculation formula considering the spatial distribution of slurry consistency proposed in this paper should be used to calculate the pressure of power law flow slurry acting on the tube sheet.

There are shallow buried bias and broken surrounding rock in the tunnel portal section. In order to explore the dynamic response law of the tunnel portal section under the action of earthquake and give the quantitative evaluation index of safety, a numerical model is established based on the No.6 tunnel of Yawan high-speed railway. Four seismic waves of artificial synthetic wave, EI wave, KB wave and WL wave are input respectively. Based on the extension theory, an extension matter-element model is established. The results of four safety evaluation indexes of bending moment, axial force, relative displacement and acceleration of the tunnel portal section under the most unfavorable seismic wave are obtained by numerical simulation method, and the safety evaluation of the No.6 tunnel portal section of Yawan high-speed railway is carried out with quantitative indexes. The seismic fortification length is proposed. At the same time, the dynamic response law of No.6 tunnel portal section of Yawan high-speed railway under different seismic waves is also analyzed. The results show that; (1) Under the action of Yawan artificial wave, the dynamic response degree of each evaluation point of the tunnel is about 1.2 times that of the other three natural waves; (2) The four evaluation indexes calculated by each seismic wave have basically the same variation law along the longitudinal direction. The peak values of axial force and bending moment appear at the arch foot of the spandrel arch, and the peak values of relative displacement occur from the inverted arch to the vault line at the entrance of the cave. The peak time of the evaluation index is slightly lagging behind the corresponding time of the peak acceleration of the seismic wave. (3) Under the action of YW wave, the seismic fortification length of No.6 tunnel portal section of Yawan high-speed railway is 45~55 m, which is 3.5~4 times of the tunnel diameter. The research results can provide reference for determining the seismic fortification length of tunnel portal section by quantitative index.

Precast concrete segment is the most commonly used lining structure form of subway shield tunnel. In order to give full play to the advantages of reinforced steel fiber concrete shield segments and obtain an accurate calculation method of crack width, four groups of 18 steel fiber reinforced concrete beam test schemes were designed. Based on the experimental data and the finite element analysis of ABAQUS, the research results show that: (1) Based on the data obtained from the test of bending beam and pure bending beam, the calculation method of crack width of reinforced steel fiber reinforced concrete pure bending and large eccentric compression members is proposed. (2) The influence of steel fiber content and reinforcement ratio on crack width is analyzed by finite element analysis. When the steel fiber content increases, the tensile strength of steel fiber reinforced concrete increases gradually, and the crack width of the component decreases gradually. When the reinforcement ratio increases, the corresponding load when the steel bar reaches the yield strength increases gradually, and the crack width decreases gradually. (3) Through the measured test of shield segment crack width, the crack width calculated by the formula and the Model Code is relatively close to the segment test results, and the average difference is 56% and 50% respectively. (4) The proposed crack width calculation method effectively considers the influence of steel fiber content and reinforcement ratio on crack width. The calculation results are more accurate and can effectively evaluate the crack width calculation of C50 steel fiber reinforced concrete shield segment.