## 1 Introduction  
A dual-roadway layout is adopted in most of the shaft-accessed coalfaces in China, and coal pillars ranging in width from 15 to 40 m are used between adjacent coalfaces in order to partition adjacent gobs and support the roof load [1]. After mining, coal pillar resources between coalfaces cannot be recovered. According to statistics, China loses about 300 million tons of coal each year due to coal pillars between coalfaces, representing a serious waste of resources. The gob-side entry retaining method [2]; the 110 method [3],which cuts the roof, relieves pressure and forms the roadway automatically; and the N00 method [4], which forms the roadway automatically with no coal pillars retained, are three commonly seen methods used to reduce the waste of coal pillar resources between coalfaces. These three methods require no coal pillar between coalfaces and thus can achieve coal-pillar-free mining. However, they fail to address the great quantity of coal-based solid waste, such as coal gangue, and are poorly applicable to complex engineering and geological conditions. Given these shortcomings, [PERSON] [5; 6] proposes a scientific mining concept of \"short filling and long mining\", in which a solid waste filling belt is formed based on the nearby gangue sorting in the underground mining area of the coal mine so as to replace the coal pillar in the same section. Although solid gangue filling can deal with coal gangue and act as a substitute for coal resources simultaneously, there is only a mediocre effect on reducing both ground subsidence and damage [7]. Paste cement filling can deal with coal-based solid waste and provide a substitute for over-ridding and marginal coal resources simultaneously, and it has a good effect on protecting aquifers and ground buildings and structures. In order to realize the coordination between coal-based solid waste disposal on a large scale and coal pillar resource recovery and to achieve the sustainable and green development of coal mines, [PERSON] [8] puts forward an integrated coal pillar excavation, filling and retention process between coalfaces. First of all, a comprehensive mechanized excavation coalface with super-large sections is arranged on the coal pillar boundary in the main roadway, and a new set of integrated excavation equipment is employed to excavate forward with super-large sections; continuous and efficient filling takes place at the rear of the excavation coalface, and coal pillars between the coalfaces are substituted with a coal gangue-cemented paste filling body. In the meantime, two parallel gate roads are automatically formed along the filling belt so as to realize coordination between the roadway excavation, solid waste disposal and coal pillar resource recovery. Finally, loss-reducing coal mining is fulfilled. This integrated coal pillar excavation, filling and retention process between coalfaces still involves several difficulties, such as the excavation and support mechanisms for roadways with super-large sections for coal pillars between coalfaces, the excavation and filling processes of the coal pillars between coalfaces, the synergistic relationship between the inter-coalface filling body and surrounding rock of roadways, etc. Among them, the realization of the one-time full-section excavation of roadways with super-large sections is premised on the integration of the \"excavation-filling-retention\" process of the coal pillars between faces, and clarifying the stress distribution characteristics and change rules of super-large sections of roadway is the key to solving the problem of this one-time full-section excavation. In the present paper, the stress distribution law and deformation and failure characteristics of the surrounding rock of super-large-section roadways are explored by combining mathematical means with numerical simulation. There have long been methods that mathematically clarify the stress distribution laws concerning surrounding rock of roadways.