当代钻孔地应力测量的主要问题

PRINCIPAL QUESTIONS OF GEOSTRESS MEASUREMENT IN BOREHOLE AT THE PRESENT TIME

近半个世纪以来,钻孔法地应力测量中尚未解决的主要问题是:假定岩石在力学性质上各向同性;没有考虑钻孔效应;忽视了测量的时间效应;简化了岩石力学性质的多变性。由于这些问题的存在,使得主应力测值的误差可达100%,主应力方向的测量误差可达90°,还可以引起主应力性质的正负变换。要进行高水平的地应力测量,必须把测量建立在岩石方学性质各向异性的基础上,减少或避开钻孔效应的影响,考虑或避开测量的时间效应,避开岩石力学性质多变性的影响,分别测量各种地应力成份,进行定点长期连续观测。

Since half century, the unsolved principal questions in geostress measurement using borehole method are hypothesizing that the mechanical property of rocks is isotropic, unthinking the borehole effect, unconsidering the measuring time effect and simplifying the changeful mechanical property of rocks. The maximum synthetic error caused by them can be up to 100% of principal stress value and 90° in principal stress orientation and the error can result in that the principal stress property may change from positive to negative. For purpose of high level geostress measurement, the measurement must be based on anisotropy of mechanical property of rocks; the borehole effect must be subtracted or avoided; the time effect in measurement be avoided or considered; the effect of changeability of mechanical property of rocks be avoided in the geostress measurement. The each component of geostress must be measured respectively and the fixed longterm continuous observation be made.