The Optimization Of Measurement Points Layout Of Displacement Back Analysis In Underground Cavern

In order to determine rock mechanical parameters, a new way was provided by displacement back analysis based on field measurement information. However, accurate site monitoring information is the premise and basis for displacement back analysis. Theoretically, the more the displacement measurement points are, the better the back analysis results are. But the cost will be greater. If the most reasonable layout of the measuring position can be chosen, and a reasonable layout program can be developed, not only be able to obtain higher accuracy requirements parameters, but also can reduce the economic cost of the project. Therefore, based on minimum variance criteria and maximum sensitivity criteria, several theory and application researches on the optimization of measurement points layout of displacement back analysis in transversely isotropic rock mass have been accomplished in this paper to determine the most appropriate position to lay measurement points.The optimization of measurement points layout of displacement back analysis in transversely isotropic rock mass is preliminary studied according to the maximum sensitivity criteria. Sensitivity criteria was derived. The results indicate that the region angle bisector of two principal stress is optimum for measurement points layout. And arrangement on the tunnel wall or at the extremes needs further determination according to derivate relationship.By numerical analysis software FLAC3 D, the optimization of measurement points layout in transversely isotropic rock mass is preliminary studied according to the maximum sensitivity criteria. For a circular roadway, the region angle bisector of two principal stress is optimum for measurement points layout. For the straight wall arched roadway, the optimum for measurement points layout on the middle of the side wall, followed on the spandrel area.The optimization of measurement points layout of displacement back analysis in transversely isotropic rock mass is preliminary studied according to the minimum variance criteria. Criterion function contained three variables parameters was derived, and the three parameter estimates were got. The higher the accuracy of the estimate is, the better the parameters are inversed. The results indicate that the range close to the tunnel wall in the direction of major principal stress is optimum for measurement points layout.