The hydromechanical coupling behavior of rocks is widely present in the fields of rock mechanics and engineering studies. Analyzing and summarizing the relevant literature, the current status of experimental and coupling theory research on hydromechanical coupling is systematically described, the commonly used numerical simulation methods and their applications are briefly introduced, and the hydromechanical coupling problems in mining engineering, water conservancy, and hydropower engineering, slope engineering, tunneling engineering, and other fields are analyzed. Regarding the current status of studies on the hydromechanical coupling behavior of rocks, the test research aspect needs to further enhance the test studies on the triaxial shear permeability of rock material, and adopt a combination of macroscopic, fine, and microscopic methods to study the hydraulic coupling problems of rock materials from different scales. To couple theory, the traditional concepts are broken through, and new coupling theories and mathematical models are used to explain and solve the relevant practical problems. Meanwhile, the application of interdisciplinary approaches to solving coupling problems in the future is emphasized. In terms of numerical simulation and engineering applications, new large data algorithms are developed to improve the efficiency of simulation calculations. In addition, consideration should be given to the numerical simulation of coupling effects, the coupled rheological effects, and the coupled dynamic properties of rock masses under high-ground stress and high water pressure.

Rock quality designation (RQD) and permeability coefficient are important reference indexes for grouting application. Based on the readily available RQD, RQD is found to have no relationship with the depth of rock stratum, and a method for calculating the mean RQD (RQD_m) of long stratum is proposed, which is applied to the calculation of RQD of grouting sections. Through Lugeon and grouting tests on the grouting sections, RQD_m of the grouting sections is found to be directly related to the average permeability coefficient, permeability, and units of grouting per amount of rock mass. It is found that RQD_m has a symmetrical relationship with permeability and grouting volume as well as a negative exponential correlation with unit grouting volume and average permeability coefficient. According to the curve of RQD varying with depth, the grouting amount at different depths can be obtained by using the fitting formula of unit grouting amount and RQD_m.

The seepage characteristics of rocks under conditions of multi-field activity have always been important in the field of rock mechanics. This study used the MTS815 multi-functional electro-hydraulic servo rock testing machine to conduct seepage tests on long-flame coal specimens under different confining pressures, water pressures, and temperatures. This paper presents and discusses the seepage characteristics of coal specimens under the action of thermal hydraulic mechanical multi-field combinations. Considering parameters such as volumetric strain, temperature, thermal expansion coefficient, and initial porosity, the relationships of each parameter with porosity were obtained. The test results revealed that the volumetric strain of coal specimens increased gradually with the increase of temperature. The dynamic viscosity of water decreased with the increase of temperature, which accelerated the movement and circulation of water molecules. The increase in temperature caused the volume of the coal specimen to expand, the pores in the coal specimen squeezed against each other, the pore volume decreased, and the size of the seepage channel slowly decreased, which inhibited the seepage process. Furthermore, permeability gradually decreased with the increase of temperature. This inhibited the occurrence of seepage, and the higher the confining pressure, the lower was the permeability. The porosity of coal specimens decreased with the increase in temperature, which had an inhibitory effect on the seepage behavior. The results of this study provide experimental and theoretical support for the safe mining of coal and rock in underground mines.

In order to investigate the impact of moisture content on energy evolution, three types of rock samples with varying moisture contents were subjected to uniaxial compression tests. The study aimed to analyze the reasons behind the differences in energy during the deformation process of rocks with different moisture contents. The findings indicate that with increasing moisture content, the peak strength and elastic modulus of the samples decrease. However, the ratio of crack initiation strength σ_ci to peak strength σ_f shows little effect, primarily because the characteristic strength ratio σ_ci/σ_f is determined by external loads. The growth rate of elastic energy reaches its maximum value in the early stage of yield, while the proportion of elastic energy reaches its peak value in the later stage of yield. In the deformation and failure process of rocks with varying moisture contents, the increment in elastic performance is smallest in the initial compaction stage for saturated rocks, whereas it is the largest in the yield stage for dry rocks. Additionally, a damage evolution equation based on energy dissipation was established and validated.