A single hole resistivity detection method for caves

Abstract

The invention discloses a single-hole resistivity detection method for karst caves. The method includes the following steps: 1. Installing a detection device: each electrode is embedded and fixed on a PVC threading pipe, and a copper core cable connected with the electrodes is threaded through the middle of the PVC threading pipe. Afterwards, connect the resistivity tester and electrodes on the surface; 2. Place the detection device: put the assembled PVC threading pipe into the advanced drill hole; The area where the cave is located can be obtained. The invention adopts boreholes for deep underground detection, has the characteristics of large detection plane range, large detection depth, and more effective data obtained, and can eliminate part of the interference in the stratum. At the same time, the basic resistivity calculation theory is used to calculate the apparent resistivity, the calculation process is simple, and it is beneficial to improve the detection efficiency.

Description

technical field [0001] The invention relates to a single-hole resistivity detection method for karst caves, belonging to the technical field of underground karst cave detection. Background technique [0002] Karst caves are underground cavities formed by the long-term dissolution of limestone by groundwater. They are divided into soil caves, unfilled caves, semi-filled caves, fully filled caves and beaded caves. The soil condition of the building foundation is closely related to the safety of the building. The existence of karst caves in the lower part of the foundation foundation may leave a serious safety hazard to the building. Therefore, it is necessary to take some measures to explore the possible existence of karst caves, to find out its type, size and location, so as to deal with the karst caves in advance. However, the traditional borehole detection range is very limited, and the ordinary resistivity law is prone to the fact that the karst cave is deep or small in v...

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Problems solved by technology

[0004] 1. The measuring points of ordinary resistivity method are arranged on the surface, and the distribution of current density in the ground decreases rapidly with the increase of depth, which limits the survey depth of electrical prospecting

[0005] 2. When the current density passing through a cave with a large buried depth is very small, even if there is a significant difference in resistivity between it and the overlying rock layer, it is difficult to affect the current density close to the ground, so it is measured on the ground The potential difference will not be affected too much, so that it cannot be accurately judged

[0006] 3. When there is an insulating layer with a very large resistivity or a good conductor with a low resistivity underground, it will hinder the distribution of current to the deep underground, resulting in a so-called shielding effect. In this case, it will lead to an effective exploration depth greatly reduced

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