多触点预压式元件的钻孔变形法地应力测量

采用多触点预压式元件的钻孔变形法地应力测量,能够测得孔壁上较多点的折算位移值,因而能够用平差术减少偶然误差,得出地应力大小和方向的最佳值。本文讨论了这种元件在绝对应力测量和相对应力测量过程中的力学作用,导出了孔壁接触点折算位移向量与元件输出向量之间的基本关系式,以及它们增量之间的关系式。本文是文献2]工作的推广。当接触点相互之间的距离变大、接触压力的相互影响减弱时,从本文基本关系式得出的极限情形与文献2]的一致。本文比文献2]进一步明确了目前实际工作中所用公式的简化前提。文末指出了用多触点元件精确测定地应力尚待解决的一些问题。

ON GROUND STRESS MEASUREMENT BY BOREHOLE DEFORMATION METHOD USING A PRE-PRESSED MULTIPROBE UNIT OF CONTACT TYPE

The use of a pre-pressed multiprobe unit of contact type in measuring ground stress can record at a time many reduced displacements of points on the wall of a borehole. After processing these recorded data with the help of the theory of errors, we can obtain the best estimates of magnitudes and directions of the ground stress. In this paper, the mechanics of a multiprobe unit when used in ground stress measurements is analysed in detail, and there are obtained two fundamental formulae, one for absolute stress measurements and the other for relative stress measurements, which indicate the relationship between the reduced displacements of points on the wall of a borehole and the outputs of the probes of the measuring unit set in the borehole. This paper is a generalization of the work published previously paper by the same author （cf. Ref. 2]）. When the distances between the points were the probes are in contact with the wall of the borehole increase indefinitely, the limiting case'in this paper gives the same results as obtained in the previous paper. The assumptions which are the basis of the simplified formulae so far used in practical work by engineers in ground stress measurement are explained more satisfactorily in this paper. At the end of the paper, a few problems together with suggestions are mentioned, which have to be resolved for the correct application of a multiprobe unit to ground stress measurements.