基于定向钻孔的地质保障技术可实现矿井致灾隐患的超前探查与治理，但受现有有线随钻测量定向钻进装备制约，存在信号传输干扰因素多、对定向钻具要求高、地层适应性差等不足，亟待开发矿用泥浆脉冲无线随钻测量系统。结合煤矿井下近水平定向钻孔施工特点，小泵量、低泵压和小直径条件下工作需要，建立了泥浆脉冲信号发生机构和水力通道模型，分析了泥浆脉冲信号传输速度、传输强度、衰减规律和传输影响因素等特性，给出了信号反射与透射、泥浆泵噪声干扰、孔内钻头旋转干扰和冲洗液流道阻塞等影响因素的针对性处理方法。分析结果表明，煤矿井下近水平定向钻进宜采用正脉冲方式进行信号传输;以清水作为冲洗液时信号传输速度为1366.20~1445.11m/s;信号脉冲幅值可通过改变流道控制阀与孔板之间的间隙进行调整;信号传输衰减系数随冲洗液流量增大而线性增大，随钻杆柱内径增大而逐渐减小，当信号发射频率f＞0.2 Hz后，衰减系数维持在0.126×10^-3 m^-1左右;采用煤矿井下常用钻杆，孔深1 500 m时孔口接收信号强度为孔内信号发射强度的73.74%~90.71%。现场试验表明，开发的矿用泥浆脉冲随钻测量系统信号传输误码率为3.2%，脉冲信号实际幅值一般小于理论计算幅值，但误差小于10%，最大实钻传输距离达到1 566 m，且具有更深的信号传输能力。

Geological guarantee technology based on directional borehole can realize the advanced detection and treat- ment of hidden hazards in underground coal mines. However,it is restricted by the existing wired MWD directional drilling equipment,because of many interference factors of signal transmission,high requirement for directional drilling tools,poor adaptability of stratum and other shortcomings,so it is necessary to develop the wireless mud plus MWD system. Combining with the construction characteristic of the near-horizontal directional borehole in underground coal mine and the working requirement under the conditions of small pump volume,low pressure and small diameter,the generation mechanism of mud pulse signal and the model of hydraulic channel are established. The characteristic of mud pulse signal about transmission speed,transmission intensity,attenuation law and transmission factors are ana- lyzed,and the pertinent treatment methods including the signal reflection and transmission,the interference from mud pump noise and bit rotation,and the blockage of fluid channel are given. The analytical results show that the mode of positive pulse is suitable for signal transmission in near-horizontal directional borehole in underground coal mine. The signal transmission speed is 1 366. 20-1 445. 11 m / s when water is used as flushing fluid. The signal pulse amplitude can be adjusted by changing the gap between the control valve of flow channel and the orifice. The attenuation coeffi- cient of signal transmission increases linearly with the increases of fluid flow rate,and decreases gradually with the in- creases of inner diameter of drill string,additionally,the attenuation coefficient is maintained at about 0. 126×10-3 m-1 when the signal transmission frequency is greater than 0. 2 Hz. The received signal intensity at orifice is 73． 74% -90． 71% of the transmission signal intensity when the depth of borehole is 1 500 m by common drill pipe in under- ground coal mine. The field test shows that the error rate of signal transmission in the mud pulse MWD system is 3． 2% ,the amplitude of actual pulse signal is less than theoretical calculation pulse signal,but the error is less than 10% ,the maximum transmission distance is 1 566 m with a deeper signal transmission capability.