## 1 Introduction  
The technology of gob-side entry retaining enables mining without the coal pillar by eliminating the section coal pillar. Traditional gob-side entry retaining technology is primarily in the form of roadside filling support, which requires the support body to have 'high strength, compressibility and tightness' to control roof subsidence and gob sealing. However, the process of constructing the roadside filling support body is complex, costly and time-consuming [1, 2]. Roof cutting and pressure relief gob-side entry retaining is based on the theory of roof cutting by'short-arm beam' [3], which eliminates the roadside filling support body and forms the roadway side with the help of the broken and expansive filling gob of rock. Compared with traditional roadside filling support gob-side entry retaining technology, this process is simple, the speed of roadway formation is fast, the cost performance is high, and the adaptability to different geological conditions is strong. It has been widely used in China [4, 5, 6]. Current roof cutting technology is primarily based on directional cumulative blasting and hydraulic fracturing. The directional cumulative blasting is simple to operate and has a large controllable range, but it has a certain impact on the safety of the stope space and is difficult to apply in high gas mines [7; 8]. Hydraulic fracturing softens the rock mass through a large number of high-pressure hydraulic fractures, which offers higher safety than shaped blasting but has higher requirements for the water stability of the roadway's surrounding rock [9; 10; 11]. In recent years, some mines have adopted an advanced arrangement of roof dense drilling and roof cutting to relieve pressure. This method has the advantages of low cost, easy operation, strong applicability and small disturbance to the surrounding rock of the roadway [12; 13; 14]  
Dense drilling technology is often used to relieve the pressure of surrounding rock in high ground-stress roadways. Many scholars have extensively studied this approach. Findings reveal that the essence of the pressure relief technology of borehole surrounding rock is to artificially weaken the local structural integrity of the roadway and transfer the stress concentration of its surrounding rock [15; 16]. The stress release caused by crack propagation and penetration between boreholes is the fundamental reason for the pressure relief effect of boreholes [17]. Increasing the aperture or reducing the spacing between boreholes will increase the degree of crack propagation and thus increase the effects of pressure relief [18]. After the excavation of dense drilling, the width ratio of the pressure relief zone can be increased by using a larger aperture and smaller spacing, and the weakening effects of dense drilling on the rock mass can be improved. Field tests prove that the discontinuous, weak surface induced by dense drilling can effectively improve the stress environment of roadways [19]. According to the deformation control effect of different pressure relief drilling parameters on high-stress roadways, the degree of pressure relief is divided into insufficient pressure relief, sufficient pressure relief and excessive pressure relief. A range of drilling parameters under sufficient pressure relief can be obtained [20]. In recent years, dense drilling technology has also been used in the process of roof cutting and pressure relief gob-side entry retaining. The use of dense drilling to weaken the roof will be subject to tensile stress concentration when the roof is bent and deformed, so that the borehole weakening zone is vulnerable to tensile failure. Dense drilling can absorb the expansion deformation of the immediate roof, reduce the deformation of some roadways and achieve the effect of roof cutting and pressure relief [21; 22].