高压氮气致裂增透实验系统的研发及应用

Development and Application of Testing System of High Pressure Nitrogen Blasting Experiment for Increasing Permeability

以气体射流冲击和高压氮气的准静态膨胀作用理论为基础,自主研制了高压氮气爆破致裂煤岩体实验系统,开展了不同氮气压力(5、7.5、10 MPa)和不同高压容器体积(1、2、3 L)条件下的高压氮气爆破致裂实验,以获得煤岩体在高压氮气爆破致裂过程中的动态变化规律。结果表明:随着氮气压力的提高,试块从最初的纵向主裂纹扩展为纵横2条主裂纹,次生裂纹更加发育,试块的裂纹增多、破碎度和裂纹扩展断裂区增大;同等压力下,随着高压容器体积的增大,试块主裂纹长度明显增加,次生裂纹扩展受到抑制。由高压氮气爆破致裂的p-t曲线分析,可将高压氮气爆破致裂过程根据其特点的不同分为3个阶段:气体射流冲击阶段、起裂阶段和断裂阶段。

The theories of air jet and quasi-static expansion of high pressure nitrogen have been laid as foundation in this paper.The testing system of high pressure nitrogen blasting experiment is independently developed to get the dynamic variation laws of high pressure nitrogen blasting in coal and rock mass. The experiments in different pressure（5 MPa, 7.5 MPa, 10 MPa）and different volumes（1 L, 2 L, 3 L） have been developed. The results showed that： with the increasing of pressure, it extends from initial longitudinal main crack to longitudinal and transverse two main cracks and the secondary cracks develop more obviously. Besides more cracks, degree of crushing is deeper and the crack propagation regions become bigger. With the expanding of device volume,the main crack becomes longer, while the secondary crack has been inhibited. According to the p-t curve analysis of the high pressure nitrogen blasting experiment, based on different characteristics in each stage, the blasting process can be divided into 3periods, air jet impingement stage, initiation stage and fracture stage.