Beijing Water Resources and Environmental Protection New Technology Development Co., Ltd.
LDS land sonar instrument has won 3 first-class provincial and ministerial awards and 1 second-class national award. It is a company with many It has utility model and invention patents, multiple data collection and data processing special software copyrights, and is a method and instrument with completely independent intellectual property rights. It has developed the fourth generation of instruments and has successfully registered multiple special trademarks. Its first-generation instrument, FY-20, was successfully developed in 1991 and put into production after passing ministerial appraisal. It was the first batch of virtual geophysical instruments produced in my country, and all data collection was controlled by a portable microcomputer. In 1993, it was upgraded to the second generation product. In 1997, Professor Zhong Shihang and Professor Sun Hongzhi began to conceive the third generation land sonar. The prototype was completed from June to August 2000. It was finalized in 2004 and named LDS-1. In 2005, the LDS-1 land sonar was produced. In order to adapt to the use of a 3-component geophone and increase the number of channels according to the user's requirements, the access channel of the LDS-1A land sonar instrument was changed to 6 channels.
In order to make the instrument have better dustproof and waterproof performance, and consider the appearance of the instrument. In 2001, we began to search for a more suitable portable industrial computer. In 2006, we selected an A770 military ruggedized notebook computer as the main industrial computer, which was connected to a famous brand data acquisition card (industrial grade) and a signal conditioning front board, and was named LDS-(3 Figure 1).
Figure 1 LDS-3 land sonar instrument
The host computer adopts the most well-known ultra-rugged product in the fully rugged notebook computer series. This industrial control model has a notebook computer that can be plugged into the capture card docking station. It not only passes the US military standard MIL-STD810G certification and meets the requirements of the IP65 standard for the harshest environments, it can also meet extremely stringent electromagnetic interference (EMI) requirements, exceeding Strong waterproof and dustproof sealed port, using full magnesium aluminum alloy casing, lightweight body and beautiful appearance. This product is equipped with a high-performance sunlight-readable LCD screen, a shock-proof hard drive, and numerous environmental temperature adaptation functions, so it operates extremely reliably and efficiently; it has stronger portability and a stronger ability to adapt to harsh working environments. Built-in DC 12V, 7800mAh high energy storage smart lithium battery, external AC-DC conversion power supply, rated power consumption is less than 25W; in order to adapt to field work, the battery can be easily replaced during work, ensuring a pure working time of more than 8 hours.
LDS-4 has a dynamic range of 108dB, a sampling rate of up to 500,000 points/second (the minimum sampling interval is 2μs), and a sampling point count of 200k sample points, ensuring that waves with frequencies from 5 to 4000Hz can be collected.
The detector adopts the company's patented ultra-wideband detector, which can collect vibration signals in any frequency band without suppression or amplification to collect waveform signals in the frequency band of 5Hz to 4000Hz (Figure 2).
Figure 2 Geophone characteristic curve and basic parameters
Figure 3 Typical amplitude spectrum of land sonar records
According to incomplete statistics, land sonar instruments have It has been successfully used in 104 projects from 1991 to 2010. Due to the characteristics of the instrument and the characteristics of the land sonar method, it has outstanding advantages in geological prediction of tunnel construction and shallow ground exploration (especially in the investigation of small and medium-sized caves):
(1) In the geological prediction of tunnel construction, the hammering source is used, the geophone is not fixed (only Vaseline is used for coupling, and the hand is pressed on the rock surface), no holes are drilled, and no explosion source is used. Mainly in Measuring lines are arranged on the tunnel face, which is convenient and fast. It can detect fault fracture zones, rock veins, caves, and underground rivers 150m away, and predict their spatial locations. In particular, it can distinguish 2 to 3 cross faults and give their direction, tendency and mileage in the tunnel. It can explore caves larger than 1m from 100m away. After hundreds of exploration forecasts and excavation inspections, the compliance rate reached over 90%, which was welcomed by the construction party, owners and supervisors.
(2) In terms of shallow ground exploration: in busy areas such as downtown Jinan, Guangzhou Huadu Expressway and its vicinity, Guangzhou New Baiyun International Airport, Hubei Shilipai Section of Hurong West Expressway, etc. Work without fear of interference from cars or pedestrians. Hammering the seismic source can explore up to 200m deep, especially single caves larger than 1m up to 100m deep. It has become a powerful tool for urban exploration and karst exploration. There are successful examples in detecting sliding surfaces on landslides caused by the Qingchuan earthquake, conducting quality inspections on thick-layer reinforced concrete structures, and exploring surrounding rock relaxation zones in underground projects. At the appraisal meeting organized by the Chinese Society of Rock Mechanics and Engineering in September 2010, the appraisal opinion was that “the technology is the first of its kind at home and abroad. It has achieved unprecedented results in the exploration of fault fracture zones and caves during tunnel construction, as well as in the shallow exploration of urban ground. Internationally leading level, with good promotion value and broad application prospects.” The main appraisal committee members are: Academician Chen Yuntai, Academician Teng Jiwen, Academician Zhou Fengjun, and Professor Cai Meifeng.