应变仪埋入式应力解除法的测量值与初期应力场的关系

RELATIONSHIP OF MEASURED VALUES OF STRESS RELIEF METHOD OF EMBEDDED STRAIN GAUGE AND INITIAL STRESS FIELD

应变仪埋入式应力解除法在测定岩体应力时,其套取岩芯孔径的大小、弹性砂浆充填的厚度都对其测定精度产生影响。为探讨该问题,在二维应力场下,就埋入式应力解除法的3种模型:一套取岩芯时的模型、围压率定试验时的模型以及理论上的围压率定试验模型进行解析分析。通过对3种模型精确解的比较,并对2种实用系统的计算,指出在套取的岩芯直径较小时,所测定岩体地应力的值远小于实际的应力场。

In the rock stress measurement with stress relief method of embedded strain gauge, both the size of core diameter and the packed thickness of elastic mortar affect the accuracy of measuring precision. In order to discuss the issue, the authors analyzed three cases of stress relief method of embedded strain gauge in secondary stress field, which are over-coring model, practical sensitivity test model and theoretical sensitivity test model. By the comparison of the exact solutions of three cases and calculation of two measurement systems, it could be found that the packing core diameter is not large enough, then measured values of ground stress of rock mass will be significantly underestimated compared with the actual stress field.