The traditional active source surface wave instrument, employing tapered velocity geophones, suffers from narrow frequency band and low longitudinal resolution. Manual movement of geophones one by one in traditional devices for measuring points results in inefficiency and inability to rapidly acquire high-density surface wave data at low cost, leading to low lateral resolution. This paper proposes a towed seismic surface wave data acquisition method suitable for hardened roads. Linear string and array towed gravity-coupled accelerometer geophones are designed to achieve high-density data acquisition with small geophone spacing, high sampling rate, and broad bandwidth. Traditionally, the influence of sampling rate on the detection accuracy of surface waves has been neglected. This paper suggests that high sampling rates can improve the accuracy of surface wave detection. Analysis of different sampling rates between model data and measured data shows that high sampling rates can suppress noise interference, amplify low-frequency energy, and ensure sufficient investigation depth. The surface wave data collected by the geophones in this study enables detailed description of velocity layer variations and identification of potential collapse locations. The application of towed seismic geophone for urban road collapse detection showcases efficient acquisition and precise detection capabilities.

In this paper, a handheld intelligent susceptibility meter was designed based on the resonance principle. A calculation formula for the resonance principle method was derived to measure the magnetic susceptibility of rock. Simulation of the influencing factors of the resonance method was conducted to explore the magnetic susceptibility of rock. The overall design of the instrument was informed by the simulation results and actual detection needs. The peripheral circuit was constructed based on LDC1614, and the inductance sensor, signal extraction program, and operation interface for the upper computer were designed. The prototype of the magnetic susceptibility instrument was completed. The instrument is portable (weighing only 0.2 kg) and is easy to operate. The measurement error is less than 5% compared with similar foreign instruments, and the accuracy of the instrument can reach 10-7. It is suitable for both field and laboratory measurements and holds practical engineering value.