REVERSE ANALYSIS OF SOIL PROPERTIES BASED ON IN-SITU DATA
OBTAINED BY ARTICURETED SHIELD
Yukihiro NAKAGAWA
Closed shield tunneling method has emerged as popular tunneling method during the past decade. Furthermore, some automatic shield control systems are based on empirical relationships and they do no have precise theoretical background. Therefore, it is difficult to control the shield in complicated geological structure and the required capacity of shield can not be predicted. A theoretical approach is necessary to solve the above mentioned problems.
In this study, the kinematic shield model, which can represent the acting load on shield with crease mechanism, was used to estimate the ground properties, such as coefficient of earth pressure at rest KH0, coefficient of subgrade reaction kH, kV, by using reverse analysis method, the ground properties were obtained by applying the direct search method to the equilibrium conditions of horizontal moment. The data used in the reverse analysis was obtained from the test site using an slurry shield with crease mechanism at very soft clay layer.
As a result, the coefficient of earth pressure at rest KH0 of this very soft clay layer is obtained about 1.2. But the coefficient of subgrade reaction kH, kV are not obtained.
It is considered that the horizontal moment increases as KH0 increase, but the horizontal moment does not increases as kH, kV increase. It is considered that this comes from the pushing distance to the ground is very small.
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