Underground abnormal body detection method

Abstract

The invention discloses an underground anomalous body detection method. The method comprises the following steps of setting an excitation point and a receiving point in a determined work area range, correspondingly arranging an excitation device and a detector, carrying out excitation at the excitation point, receiving an anomalous body reflection signal by the detector, converting the reflection signal, extracting a resonant frequency and analyzing the size of an underground anomalous body structure. and the stratum position where the underground abnormal body structure is located being further determined by combining with frequency forward modeling so that residual waste structures can be cleared away before construction. The method is advantaged in that the detection process is cost-saving, simple and convenient, single-point observation is achieved, earth surface adaptability is high, the low-frequency exploration penetrability is high, the number of shielding layers is small, detection precision is high, the result is visual, defects of an existing underground anomalous body structure detection method are overcome, and the method has higher actual popularization and application value.

Description

technical field [0001] The invention belongs to the field of underground abnormal body detection, and in particular relates to a detection method for the position and size of abandoned anchor rods, broken piles, structural supports and the like remaining in the foundation before building construction. Background technique [0002] With the development of my country's economy and the continuous advancement of urbanization, the scale of demolition of old buildings and the construction of new buildings has continued to expand, and the volume of foundations has increased accordingly. Nowadays, there are many old buildings in almost every city without pile foundation data such as pile foundation embedment depth and pile foundation type. Old buildings may adopt expanded foundation (strip, box foundation) or pile foundation ( prefabricated piles). Old buildings, especially those with a long history, are prone to breakage of the pile foundation due to foundation settlement, groundw...

AI Technical Summary

Problems solved by technology

Old buildings, especially those with a long history, are prone to breakage of the pile foundation due to foundation settlement, groundwater corrosion, and construction disturbance in adjacent areas. After demolition, there are still undiscovered deep-buried residual broken piles in the foundation soil and old piles, which have a serious impact on subsequent construction

[0003] At present, the geophysical prospecting methods for the detection of the above-mentioned underground anomalies are seldom used. It is difficult to ensure the accuracy of the detection of deep-buried fractures in old buildings, abandoned pile foundations or residual anchor rods and structural supports in foundation pit engineering by using conventional ground geophysical prospecting techniques.

Conventional geophysical prospecting technologies on the ground mainly include noble high-density electrical method, geological radar, resistivity method, and frequency conversion method. Anomalies in the Foundation

The conventional high-density resistivity method only measures one device, and its acquisition method is backward, the amount of data collected is small, and the work efficiency is low; the detection depth of ground radar is limited, and it is strongly disturbed by the urban environment. It is difficult to meet the requirements of actual exploration when dealing with complex geological problems. Requirements: Resistivity method is not sensitive enough to small anomalies, data analysis is relatively complicated, there are large errors, and it cannot accurately reflect the resistivity of geological bodies, and the measurement results are greatly affected by surface conditions and climate factors , causing great interference in the measurement results; the frequency conversion method is one frequency, one frequency measurement, not only the work efficiency is low, but also due to the uncertainty of external interference, it is difficult to improve the measurement accuracy, especially in the measurement frequency When similar, the error is larger

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