The vertical structural stability of floating drilled shaft during sinking is an important practical issue on the safety of boring technique in the deep and thick alluvium. In fact, the vertical structural stability of shaft lining is a matter of overturn buckling. Theoretical analysis shows that the height of balance water (HBW) is the most important factor for the vertical structural stability of shaft lining. If the HBW is controlled in a reasonable range, the shaft lining will not buckle during construction. The shaft lining is regarded as a slender bar with closed bottom and floating in the mud while sinking. According to the mechanical analysis on the shaft lining from floating and sinking to the process of contacting the well bottom, a reasonable range of the HBW is deduced. Finally, with practical instances, the author in this article introduces the calculation principle in vertical structural stability of shaft lining while sinking and floating using finite element method (FEM). The simulation results show that in the reasonable range of HBW, the stability of shaft lining increases as the height of balance water goes up.

Based on deep in-situ stresses measurement data in new and old mines of Huainan mining area, in-situ stresses characteristic is researched by statistical analysis with multiple methods. Research results indicate that in-situ stresses of deep rock mass in Huainan mining area are located at high level. Scatter plots of vertical stresses, horizontal principal stresses and lateral pressure ratios variation with depth are presented, then, respective regression equation is obtained. The statistical results are helpful to finding out macroscopical characteristic of deep in-situ stresses field in Huainan mining area. The research results can also provide important reference frame for design and computation of underground caverns in Huainan mining area.

In order to achieve three-dimensional automatic splicing from the multi-angle, the paper presents a new splicing method. The method utilizes the invariance of the spatial characteristics of the characteristic landmarks and then marks the characteristic landmarks by introducing the angle collection between the characteristic landmarks, and match in space for the characteristic landmarks within two perspective regional based on this characteristic collection. This method eliminates the tedious encoding process of the landmarks, so improves the spatial matching rate and ensures the matching accuracy. In addition, in the process of striking the three-dimensional coordinates of the landmarks, this paper strikes image coordinate of the characteristic signs circle center by introducing the regional connectivity feature flag. This method eliminates interference from unwanted areas, and distinguish between the various signs round independence and improves the strike rate of the circle center. At the end rotation matrix R and translation vector T of the coordinate system normalization are solved by the quadruple method. Examples show that the algorithm has strong robustness, can realize quickly, automatic stitching for the visual data, and has the very good practical value.

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