真三维应力下煤岩水力润湿范围动态监测试验系统研制

Development of dynamic monitoring test system for coal and rock hydraulic wetting range under true three-dimensional stresses

为了研究深部煤层复杂应力环境下煤岩的力学特性与渗流润湿规律,自主研制真三维应力下煤岩水力润湿范围动态监测试验系统,其主要由应力加载系统、液压伺服系统、数据采集与控制系统、声发射监测系统等组成。该系统的创新性及先进性如下:(1)开展煤岩不同地应力、不同流体压力、不同采动应力、不同温度等多场耦合条件下的试验研究;(2)进行不同地应力、不同流体压力、不同温度条件下煤岩的水力压裂试验,研究煤岩裂纹起裂位置及裂隙扩展等的变化情况;(3)开展不同地应力及采动应力下多孔介质水、气等多相流体各向异性渗流试验,深入研究试样的各向异性对渗流效果产生的影响;(4)进行不同地应力及采动应力条件下多孔介质液相流体的润湿试验研究,并结合声波测试分析液相流体在不同流体压力下的动态润湿范围及润湿过程;(5)全密封设计,在注水管前端安装球形声发射探头,压头上安装声波传感器接收球形声发射探头发射的激励信号,试样用可拆卸压头单独固定并密封,保证声发射系统正常工作下试样的整体密封。通过一系列试验对该系统的准确性和可靠性进行验证,结果表明试验系统准确可靠。该系统为多场多相耦合条件下煤岩水力压裂、渗流、润湿全过程的规律研究及变化机制提供新手段。

In order to study the mechanical properties and seepage wetting law of coal and rock under the complex stress environment of deep coal seams,a dynamic monitoring test system for the hydraulic wetting range of coal and rock under true three-dimensional stresses is independently developed. The system is mainly composed of a stress loading system,a hydraulic servo system,a data acquisition and control system and an acoustic emission monitoring system. The system has the capabilities of carrying out experimental research on coal and rock under different ground stresses,different fluid pressures,different mining stresses,different temperatures and other multi-field coupling conditions,conducting the hydraulic fracturing test of coal and rock under different ground stresses,different fluid pressures and different temperature conditions in order to study crack initiation position and crack propagation of coal and rock,performing the anisotropic seepage test of multi-phase fluid including water and gas under different geostresses and different mining stress to study the influence of the anisotropy of samples on the seepage effect in-depth,and carrying out wetting test research of liquid phase fluid in porous media under different ground stress and mining stress conditions for analyzing the dynamic wetting range and wetting process of the liquid phase fluid under different fluid pressures combined with acoustic wave test. The innovation and advancement of the system include fully sealed design. Specifically,a spherical acoustic emission probe is installed at the front end of the water injection pipe,an acoustic wave sensor is installed on the pressure head to receive excitation signal from the spherical acoustic emission probe,and the sample is individually fixed and sealed with a detachable indenter,ensuring the overall sealing of the sample under the normal operation of the acoustic emission system. The accuracy and reliability of the system are verified through a series of tests. This system provides a new method for studying the law and change mechanism of the whole process of coal and rock hydraulic fracturing,seepage and wetting under the condition of multi-field and multi-phase coupling.