Theoretische Untersuchung zur Ortsbruststabilität

Abstract

Eine wichtige Aufgabe beim Tunnelbau in Lockergestein ist die Bestimmung des erforderlichen Stützdrucks der Ortsbrust. Dazu wurden diverse Berechnungsmodelle entwickelt, einige davon erst im Laufe der letzten Jahre. In diesem Beitrag wird zunächst ein mechanischer Ansatz analytisch hergeleitet und dann auf Unterschiede zu bestehenden Modellen untersucht. Anhand eines Rechenbeispiels wird aufgezeigt, wie sich diese Unterschiede auf die Berechnungsergebnisse einer fiktiven Problemstellung auswirken. Die große Schwankungsbreite der Resultate verdeutlicht, daß auf diesem Gebiet immer noch ein Forschungsbedarf besteht.

Face Stability Analysis of Shield Tunnel Using Slip Line Method

“…Figure 5, F is a point on the upper edge OB of the tunnel and q is uniform load applied to the ground. e effect of the cover layer can be considered as a distribution force [39][40][41].…”

Face Stability Analysis of Shield Tunnels in Homogeneous Soil Overlaid by Multilayered Cohesive-Frictional Soils

“…The new failure mechanism considers the effect of the cover layers as a distributed force according to the Terzaghi earth theory. The same treatments were adopted in the works of Broere [18]; Kirsch and Kolymbas [19]; Anagnostou [20]; and Anagnostou and Perazzelli [21], which are based on the limit equilibrium method.…”

“…For cohesive-frictional soils, the results obtained from experimental tests and numerical simulations show that the failure of soil in front of tunnel face demonstrates two main features, that is, shear failure band in the lower part and pressure arch effect in the upper part. The existing researches [18][19][20][21] considered the effect of the cover layers as a distributed force and achieved satisfactory results, which is calculated using the Terzaghi earth pressure theory. In this paper, the distributed force acting on the two truncated cones is also calculated by Terzaghi earth pressure theory as shown in Figure 2.…”

“…The stability of tunnel face in cohesive-frictional soils has been analyzed by using experimental tests (laboratory centrifuge tests [1][2][3] or 1 g model tests [4][5][6]) and the numerical simulations (the Finite Element Method [7][8][9], the Finite Difference Method [6,10,11], and the Discrete Element Method [12][13][14]). Both the limit equilibrium methods [15][16][17][18][19][20][21][22][23] and the limit analysis methods [9][10][11][24][25][26][27][28][29][30][31] were used by other researchers to investigate the stability of tunnel face in cohesive-frictional soils. Actually, from the analytical approaches mentioned above, it can be concluded that either limit equilibrium methods or limit analysis methods have advantages and disadvantages.…”

Numerical investigation of the tunnel face stability

“…is compared with real ratio (u/umax) from the numerical analysis in two characteristics positions along the tunnel axis: in the tunnel face (x = 0m) and five meters (x = +5m) in front of tunnel face in the soil mass. The previous comparison is presented in Figures 5 51. and 5.52.…”