受重力倾角效应和多次采动影响，急倾斜煤层走向长壁工作面顶板垮落及矸石充填沿倾向具有非线性特征，导致工作面下端头回采巷道围岩应力环境复杂，易出现应力型变形破坏，沿空巷道留设与支护难度大，严重制约了沿空留巷无煤柱开采在急倾斜煤层的应用与推广。

以铁山南煤矿-1211（21）工作面沿空留巷为工程背景，采用物理相似材料模拟、数值计算、理论分析和工业性试验等研究方法，分析了急倾斜煤层无煤柱开采顶板垮落运移充填特征、沿空留巷围岩应力分布与变形特征以及围岩承载结构稳定性，并提出了沿空留巷围岩控制原则及支护技术。主要研究结论如下：

（1）一次采动阶段工作面倾向下部区域直接顶形成悬臂梁结构，其上方基本顶呈现倾向梯阶铰接结构，对采场覆岩起主要控制承载作用，覆岩承载拱呈倾斜非对称状，沿空巷道处于覆岩承载拱下受承载拱内岩体自重；二次采动阶段下工作面承载拱与上工作面承载拱关联，形成一大一小“双拱”结构，上工作面承载拱拱高大于下工作面。上工作面开采后倾向下部顶板位移量小于倾向中上部，下工作面采动会引发上工作面采空区矸石二次运移。

（2）掘巷期沿空巷道围岩应力和变形呈非对称分布特征，顶底板移近量大于两帮移近量。随着与工作面煤壁距离增加，一次采动阶段工作面前方巷道两帮侧向支承压力峰值逐渐减小，工作面后方巷道煤帮支承压力和采空区压实应力至工作面后方50 m后趋于稳定；根据巷道变形收敛速度可将其划分为原岩应力区、超前影响区、留巷变形区和留巷稳定区，分别表现为基本不变、缓慢变形、快速变形及趋于稳定的特征。二次采动阶段围岩变形明显加剧，矮帮水平位移大于高帮水平位移。针对沿空巷道顶底板和高帮产生明显变形破坏的关键部位，需实施差异化的支护策略。

（3）沿空留巷围岩承载结构由煤帮、“巷旁支护体+矸石充填体”及顶板组成，构建了一次采动留巷变形阶段和二次采动超前影响阶段倾向下部区域第1梯阶关键岩块力学模型，计算了不同阶段关键岩块维持稳定所需的巷旁支护体支护阻力。计算了巷旁支护体抗冲击力，建立了垮落充填矸石对巷旁支护体侧向压力分析模型，给出了巷旁支护体侧向压力解析表达式，得到了巷旁支护体回转失稳和滑移失稳判据，回转失稳易发生在一次采动留巷变形阶段，滑移失稳易发生在二次采动超前影响阶段。

（4）提出了高强度非对称支护、刚柔结合支护及局部加强支护三位一体的急倾斜煤层沿空巷道围岩控制原则和非对称联合支护技术；在该支护条件下，一次采动阶段留巷段顶底板移近量减少了67.24%、两帮移近量减少了66.43%，二次采动阶段超前段顶底板移近量减少了55.31%、两帮移近量减少了46.61%，两帮垂直应力集中峰值和范围均明显减小。现场工业性试验证明，非对称支护有效控制了顶板破碎和两帮变形，整体支护效果良好。

Under the influence of gravity dip angle effect and multiple mining, the roof caving and gangue filling of longwall working face along the strike of steep coal seam have nonlinear characteristics along the dip direction, which leads to the complex stress environment of surrounding rock of mining roadway at the lower end of working face, and is prone to stress-type deformation and failure. It is difficult to retain and support gob-side entry, which seriously restricts the application and promotion of gob-side entry retaining without coal pillar mining in steep coal seam.

Taking the gob-side entry retaining of-1211(21) working face in Tieshannan Coal Mine as the engineering background, the physical similar material simulation, numerical calculation, theoretical analysis and industrial test were used to analyze the characteristics of roof caving, migration and filling, the stress distribution and deformation characteristics of surrounding rock and the stability of bearing structure of surrounding rock in steeply inclined coal seam without coal pillar mining. The control principle and support technology of surrounding rock in gob-side entry retaining are put forward. The main results are as follows:

(1) In the first mining stage, the working face inclines to the direct roof of the lower area to form a cantilever beam structure, and the basic roof above it presents a inclined step hinge structure, which plays a major role in controlling the bearing capacity of the overlying strata of the stope. The bearing arch of the overlying strata is inclined and asymmetric, and the roadway along the goaf is under the bearing arch of the overlying strata. The weight of the rock mass in the bearing arch; in the secondary mining stage, the bearing arch of the lower working face is associated with the bearing arch of the upper working face, forming a large and small 'double arch' structure, and the bearing arch of the upper working face is higher than that of the lower working face. After the mining of the upper working face, the displacement of the inclined lower roof is less than that of the middle and upper parts of the tendency, and the mining of the lower working face will cause the secondary migration of the gangue in the goaf of the upper working face.

(2) The stress and deformation of the surrounding rock of the gob-side entry during the roadway excavation period are asymmetrically distributed, and the convergence of the roof and floor is greater than that of the two sides. With the increase of the distance from the coal wall of the working face, the peak value of the lateral abutment pressure of the two sides of the roadway in front of the working face gradually decreases in the first mining stage, and the abutment pressure of the coal side of the roadway behind the working face and the compaction stress of the goaf tend to be stable after 50 m behind the working face. According to the convergence rate of roadway deformation, it can be divided into original rock stress zone, advanced influence zone, roadway deformation zone and roadway stability zone, which are basically unchanged, slow deformation, rapid deformation and stable. The deformation of surrounding rock in the secondary mining stage is obviously intensified, and the horizontal displacement of the low side is greater than that of the high side. In view of the key parts of the roof, floor and high side of the gob-side entry that have obvious deformation and failure, a differentiated support strategy needs to be implemented.

(3) The surrounding rock bearing structure of gob-side entry retaining is composed of coal side, 'roadside support body + gangue filling body' and roof. The mechanical model of the first-stage key rock block in the lower part of the first-stage mining deformation stage and the second-stage mining advance influence stage is constructed, and the support resistance of the roadside support body required to maintain the stability of the key rock block in different stages is calculated. The anti-impact force of the roadside support body was calculated, and the lateral pressure analysis model of the roadside support body caused by the caving filling gangue was established. The analytical expression of the lateral pressure of the roadside support body was given, and the rotary instability and slip instability criteria of the roadside support body were obtained. The rotary instability is easy to occur in the deformation stage of the primary mining roadway, and the slip instability is easy to occur in the advanced influence stage of the secondary mining.

(4) The surrounding rock control principle and asymmetric combined support technology of gob-side entry in steeply inclined coal seam are put forward, which is composed of high strength asymmetric support, rigid-flexible combined support and local strengthening support. Under this support condition, the roof and floor convergence of the retaining section in the first mining stage is reduced by 67.24%, and the convergence of the two sides is reduced by 66.43%. In the second mining stage, the roof and floor convergence of the advanced section is reduced by 55.31%, and the convergence of the two sides is reduced by 46.61%. The peak and range of vertical stress concentration in the two sides are significantly reduced. The field industrial test proves that the asymmetric support effectively controls the roof breakage and the deformation of the two sides, and the overall support effect is good.