Calculation of angle parameters of non-principle section observation station under thick loose bed

In this paper, with the low precision of angle parameters of non-principle section observation station which was calculated under thick loose bed, from the perspective of amending stochastic model, the conception of fitting weight was concluded based on analyzing the residual sequence of subsidence. The sequence of subsidence was used to construct fitting weight model of probability integral method based on least squares estimation. The author designs 3 computing solutions, and analyses various solution´s fitting result from the perspective of residual sequence of subsidence, critical deformation value, mean square error of residual and so on. At last, The main conclusions is that, in the condition of thick loose bed,the whole fitting result of equal weighted estimate is better than unequal weighted estimate,and the fitting weight 1/|W_i| could effectively improve the calculation precision of boundary angle and movement angle.