煤矿井下随钻测量数据声波传输系统

Acoustic transmission system of measurement data while drilling in underground coal mine

煤矿井下坑道钻探是防治瓦斯和水突出最直接、最有效的技术手段,常规回转钻进工艺因为工艺简单、成孔速度快和设备要求低等优点成为煤矿坑道钻探的主流施工方式,但其钻进过程中不能进行钻孔轨迹随钻测量,给煤矿安全开采留下了安全隐患。针对常规回转钻进过程中无法随钻测量钻孔轨迹的关键问题,进行随钻测量数据声波传输的研究,弥补现有随钻测量数据传输方式应用于常规回转钻进的不适应性。首先,通过建立钻杆柱中声波传输数学模型、借助仿真分析软件和搭建声波传输特性试验平台,得到声波在不同钻杆柱结构中传播时幅值衰减和波形变化规律,为数据传输速率的确定提供理论依据;其次,通过建立稀土超磁致伸缩换能器输出特性数学模型和优化激励线圈和预压力系统参数,研制钻孔内声波信号发送装置,为声波传输系统提供大功率高精度信号源;然后,针对接收信号的波形识别问题,通过对识别的信号提取多维特征向量,构建支持向量机分类器,提出SVM多维特征向量提取的波形识别方法,解决煤矿复杂工况条件下声波信号的智能识别问题;最后,通过搭建的随钻测量数据传输平台验证系统在传输距离289.5 m和传输速率10 bit/s条件下的运行效果,证明各模块理论模型、设计方法和整体系统的科学性和有效性。

The underground roadway drilling is the most direct and effective technical means to prevent gas and water outburst.The conventional rotary drilling technology has become the mainstream method of the roadway drilling because of its advantages of simple technology,fast hole forming speed and low equipment requirements.However,the drilling trajectory measurement while drilling cannot be carried out in the process of drilling,which leaves a hidden risk to the safety of coal mining.In view of the key problem that conventional rotary drilling is unable to measure the drilling trajectory while drilling,the research on the acoustic transmission of measurement data while drilling is carried out to overcome the inadaptability of the existing measurement data transmission mode while drilling applied to conventional rotary drilling.First of all,by establishing the mathematical model of acoustic wave transmission in the drill string,using the simulation analysis software and setting up the acoustic wave transmission characteristics test platform,the amplitude attenuation and wave shape change rules of acoustic wave propagation in different drill string structures are obtained,which provides the theoretical basis for the determination of data transmission rate.Secondly,through the establishment of the mathematical model of the output characteristics of the rare-earth giant magnetostrictive transducer and the optimization of the parameters of the excitation coil and the pre pressure system,the acoustic signal transmitting device in the borehole is developed to provide a high-power and high-precision signal source for the acoustic transmission system.Then,aiming at the problem of waveform recognition of the received signal,by extracting multi-dimensional feature vector from the identified signal,a SVM classifier is constructed,and a waveform recognition method of multi-dimensional feature vector extraction is proposed to solve the problem of intelligent recognition of acoustic signal under the complex working conditions of coal mine.Finally,the operation effect of the system under the condition of 289.5 m transmission distance and 10 bit/s transmission rate is verified by the MWD data transmission platform built,which proves the scientificity and effectiveness of the theoretical model,design method and overall system of each module.