Method for calibrating rock creep damage and fracture surface by using high-density resistivity

Abstract

The invention provides a method for calibrating rock creep damage and fracture surface by using high-density resistivity. The method comprises the following steps: S1, drilling; S2, mounting an electrode wire; S3, performing vacuum water saturation treatment; S4, performing surface water sealing treatment; S5, mounting a strain gauge; S6, connecting the electrode wire with a high-density resistivity instrument; S7, placing on a press machine; S8, measuring initial resistivity data when the instrument is not loaded; S9, starting the press machine; S10, storing the data in real time until a rocktest piece is crushed; S11, processing the data; and S12, comprehensively calibrating the development conditions of the rock creep damage and potential fracture surface according to an obtained resistivity-time curve, a resistivity-strain curve, a stress-strain curve, a time-strain curve and a rock apparent resistivity profile map. According to the method provided by the invention, the rock testpiece is measured by adopting the high-density resistivity instrument, and the defects of relatively large errors, few measuring points, poor intuition and the like of experimental data of a dipolar method and a quadrupole method are overcome.

Description

technical field [0001] The invention belongs to the field of rock mechanics engineering, and relates to a method for real-time measurement of creep rock high-density resistivity, in particular to a method for calibrating rock creep damage and fracture surface by using high-density resistivity. Background technique [0002] Water inrush is a common geological disaster in tunnel engineering construction. Generally, tunnel water inrush can be divided into "instantaneous water inrush" and "lag type water inrush". Water inrush occurs immediately after excavation. Delayed water inrush refers to water inrush that occurs after a period of creep after rock mass excavation. The time span can range from hours to months. There is a delay effect in time for the occurrence of damage. [0003] Resistivity is a basic physical quantity of rock, which is closely related to the porosity, density, water content and fracture development of rock. When the rock is loaded, the evolution of the in...

AI Technical Summary

Problems solved by technology

[0006] The existing resistivity measurement methods mainly include the two-pole method and the four-pole method, but there are almost no studies on the use of high-density resistivity meters to measure rock resistivity.

The two-pole method is to arrange the electrodes symmetrically on both ends of the rock specimen to directly measure the resistivity, but due to the existence of contact resistance, there is a large error in the test data

The four-pole method contains four electrodes, A, B, M, and N, among which A, B are power supply electrodes, M, and N are measurement electrodes. There are few points, and it cannot truly reflect the resistivity changes at different positions inside the rock when creep failure occurs

[0007] At present, most of the research on rock resistivity is still in the study of resistivity change in one side and one direction. Because rock is an anisotropic body, it is difficult to determine the direction of internal crack expansion during the loading process. Therefore, the rock apparent resistivity profile measured only on one side and one direction cannot accurately calibrate the position of rock creep damage and potential fracture surface

[0008] In the research on the characteristics of rock apparent resistivity anisotropy, most of each survey line only arranged 4 or 8 electrodes, and only studied the resistivity anisotropy of one or two depth layers, lacking the research on the anisotropy of deeper depth. The research on resistivity anisotropy makes it difficult to obtain information on potential fracture surfaces during rock creep

[0009] The layout of the counter electrode is mostly directly pasted on the surface of the rock sample with conductive glue. The disadvantage of this method is that it is greatly affected by human operation, it is easy to fall off, and the wire and the rock cannot be fully contacted.

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