A Semi-Automatic Coupling Geophone for Tunnel Seismic Detection

Abstract

The tunnel seismic method allows for the detection of the geology in front of a tunnel face for the safety of tunnel construction. Conventional geophones have problems such as a narrow spectral width, low sensitivity, and poor coupling with the tunnel wall. To tackle issues above, we propose a semi-automatic coupling geophone equipped with a piezoelectric sensor with a spectral range of 10–5000 Hz and a sensitivity of 2.8 V/g. After the geophone was manually pushed into the borehole, it automatically coupled with the tunnel wall under the pressure of the springs within the device. A comparative experiment showed that the data spectrum acquired by the semi-automatic coupling geophone was much higher than that of the conventional geophone equipped with the same piezoelectric sensor. The seismic data were processed in combination with forward modeling. The imaging results also show that the data acquired by the semi-automatic coupling geophone were more in line with the actual geological conditions. In addition, the semi-automatic coupling geophone’s installation requires a lower amount of time and cost. In summary, the semi-automatic coupling geophone is able to efficiently acquire seismic data with high fidelity, which can provide a reference for tunnel construction safety.

The Electrodegradation Process in PZT Ceramics under Exposure to Cosmic Environmental Conditions

“…In the Raman spectrum of the yellow part of the ceramics, these peaks can be identified (red curve in Figure 4e). Close to the electroreduced blackened parts, these peaks vanish, but no new ones can be detected, indicating that the transformation of the crystal changes mainly changes the electronic structure by inducing d 1 states, but no evidence for a significant change in the crystallographic structure can be detected. In order to obtain a more detailed insight into the properties of the electro-reduced region, the same piece, which was investigated by optical microscopy, was analysed by Raman spectra-microscopy.…”

“…Extreme environmental operating conditions for piezoelectric sensors or actuators for geological [1], industrial, medical [2], military [3], and other applications have been achieved, for example, under high temperatures, with high mechanical-electrical loads and/or humidity conditions [4,5]. However, the design of piezoelectric sensors for space technology must consider electrodegradation under vacuum conditions [6][7][8][9].…”

“…The evidence of oxygen effusion allows the electroreduction to be classified as a typical reduction reaction (deoxidation) consistent with point defect chemistry (see Equation (1) for the removal of oxygen in Kroeger-Vink notation [46]):…”

A Seismic Data Acquisition System Based on Wireless Network Transmission

“…Traditional wired seismic exploration equipment has bulky cables making it very difficult to artificially deploy geophones in complex environments, thus making it impossible to meet the requirements of seismic exploration [ 2 , 3 ]. The rapid development of exploration equipment has mainly manifested in the following two aspects: the demand for mineral resources, which is continuously increasing, and seismic exploration areas, which have gradually developed into complex environments such as hills and rainforests [ 4 , 5 ]. The demand for “high-efficiency, wideband and high sensitivity“ equipment has prompted the development of seismic exploration instruments towards flexible and portable large-scale wireless ad hoc networks [ 6 ].…”

Rigidity effect of the mine geophone mounting on its frequency response

“…New designs of seismic receivers are proposed noting the experimentally discerned dependence on the installation con ditions of sensors in [5,6]. Producers offer a more rigid ground coupling in these designs in [7]. However, this problem is clearly not paid enough attention in mine seismic acoustics.…”