我国大倾角煤层赋存范围广且多为稀缺煤种，开采此类煤层对于我国区域经济社会发展具有重要的支撑作用。伪俯斜长壁综采方法是常用的大倾角煤层开采方法，其异形采场空间下，顶板变形破坏运移和垮落充填特征较一般大倾角煤层开采时更加复杂，因此，深入研究大倾角中厚煤层伪俯斜工作面顶板破断机理，对现场安全生产具有重要的理论意义。
以四川绿水洞煤矿3222工作面为研究对象，采用数值模拟实验、三维物理相似模拟实验、理论分析及现场实测的研究方法，对大倾角中厚煤层伪俯斜工作面空间形态演化规律、顶板破断机理进行了分析研究，结果表明：
（1）3222伪俯斜工作面开采时，围岩应力轮廓沿倾斜方向呈非对称拱壳状，工作面顶板应力分布形态沿倾斜方向呈上大下小的特点。工作面前方煤壁及边界煤柱区域均产生应力集中，且在同一垂直应力下工作面顶板应力轮廓形态会随着顶板层位的升高而减小。在工作面推进度一定时，随着伪斜角的增加，基本顶变形区域由近似矩形变为近似平行四边形，工作面前方基本顶在倾向上形成上小下大的非对称塑性破坏区；在伪斜角一定时，随着工作面推进度的增加，基本顶应力影响区域及变形破坏范围均随之增加。
（2）低位直接顶随采随冒，较高层位直接顶滞后工作面约6 m发生破断垮落。基本顶初次破断顺序为“倾斜中部→倾斜上部→倾斜下部”，初次来压步距约为30 m，基本顶周期破断顺序为“倾斜上部→倾斜中部→倾斜下部”，周期来压步距在9~15 m。基本顶整体破断轮廓呈倾斜“O”形，破断区域局部裂隙沿伪斜方向呈斜“X”形分布。周期破断时基本顶悬露长度呈倾斜下部>倾斜上部>倾斜中部的特点，垮落顶板在倾斜中部堆积充填且沿走向延伸，呈倾斜中上部大于下部的非均匀充填特征。
（3）建立了平行四边形板和走向岩梁的力学模型，分别推导出基本顶初次破断和周期破断的挠度、弯矩及内力公式，并给出基本顶破断判据。基本顶在初次破断时平行四边形板两长边会最先发生拉伸断裂，中部下表面和两长边上表面均呈拉伸破坏，其次在板的中部产生沿伪斜方向的“O”型圈，局部形成非对称的“X”状裂缝，顶板主应力和破断形态均呈非对称倾斜“O-X”状；初次破断时平行四边形板最大挠度值与伪斜角呈反比，周期破断时基本顶岩梁沿走向的破断位置位于工作面煤壁前方约3m处。
（4）现场实测表明，绿水洞3222工作面倾斜上部和下部采空区空间均呈“拱壳状”，但上部有三角状临空界面形成，倾斜中部有大量破断垮落顶板堆积充填，与实验研究结论一致。现场实测验证了存在倾斜中部采空区大尺寸矸石堆积，中上部垮落顶板堆积程度大于倾斜下部区域的非对称充填现象。大倾角中厚煤层伪俯斜工作面倾斜中部堆积充填影响因素有采高、顶板岩性及伪斜布置方式。本研究为该类矿井顶板稳定性控制及来压预测提供了重要的理论支撑。

The occurrence range of steeply dipping coal seam in China is wide and most of them are scarce coal. The mining of this kind of coal seam plays an important supporting role in China's regional economic and social development. The pitching oblique longwall fully mechanized mining method is a commonly used mining method for steeply dipping coal seam. In the special-shaped stope space, the characteristics of roof deformation, failure, migration and caving filling are more complicated than those of general steeply dipping coal seam. It is of great theoretical significance to study the roof fracture mechanism of pitching oblique working face in steeply dipping coal seam with medium thick.
Taking the 3222-working face of Lvshuidong coal mine in Sichuan Province as the research object, using the comprehensive research means of numerical simulation experiment, theoretical analysis, three-dimensional physical similarity simulation experiment and field measurement, the spatial shape evolution law of pitching oblique stope and roof spatial fracture mechanism in steeply dipping medium thick coal seam were analyzed and studied. The main conclusions are as follows:
(1) When the pseudo-inclined working face is mined, the stress profile of surrounding rock shows an asymmetric arch shell along the inclined direction. The stress distribution pattern of roof is large small in the lower direction. Stress concentration occurs in the coal wall and boundary coal pillar area in front of working face, and the stress profile of working face roof decreases with the increase of roof layer under the same vertical stress. When the working face advance degree is constant, the deformation area of the main roof changes from approximate rectangle to approximate parallelogram with the increase of pseudo bevel angle. The main roof in front of the work tends to form an asymmetrical plastic destruction zone with a small large size. When the pseudo slope angle is constant, with the mining of coal seam, the influence area of the main roof stress and the deformation failure range increase.
(2) In the mining of long-wall pitching oblique stope in steeply dipping coal seam, the low-level immediate roof falls with mining, and the relatively high-level immediate roof generally breaks and collapses about 6m behind the working face. The first fracture sequence of the main roof is "inclined middle → inclined upper → inclined lower", and the first weighting distance is about 30 meters. The periodic fracture sequence of the main roof is "inclined upper part → inclined middle part → inclined lower part", and the periodic weighting distance is about 9~15 meters. The overall fracture profile of the main roof is in the shape of an oblique "O", and fractures in the fracture area are in the shape of an oblique "X" along the pseudo-oblique direction. During periodic fracture, the overhang length of main roof is inclined lower part> inclined upper part> inclined middle part.
(3) By establishing the mechanical models of the parallelogram plate and the strike beam, the deflection, bending moment and internal force formulas of the initial and periodic fracture of the main roof are deduced respectively, and the criterion of the main roof fracture is given. When the roof first breaks, the two long sides of the plate break first, followed by the middle area of the roof, the lower surface of the middle part and the upper surface of the two long sides are tensile damaged. In the middle of the roof plate, an "O" ring along the pseudo-oblique direction is generated, and an asymmetric "X" crack is formed locally. The principal stress and fracture morphology of the top plate are asymmetrically inclined "O-X" shape. When the parallelogram plate first break, the maximum deflection is inversely proportional to the pseudo bevel angle. During periodic fracture, the fracture position of the main roof rock beam is about 3 meters in front of the coal wall of the working face.
(4) The field measurement shows that the space of the inclined upper and lower goaf of Lvshuidong 3222 working face is in the shape of arch shell, but a triangular free interface is formed in the upper goaf. There are a large number of broken and collapsed roof accumulated and filled in the middle of the slope. which is consistent with the experimental research conclusion. The field measurement verified the existence of large-scale gangue accumulation in the inclined central goaf, resulting in the asymmetric filling phenomenon that the accumulation degree of the collapse roof in the middle and upper part is greater than that in the inclined lower part. The influencing factors of the filling in the inclined middle of the pitching oblique stope are coal thickness of working face, roof lithology and pseudo inclined arrangement of working face. It has important theoretical significance for the roof stability control and prediction of incoming pressure for this kind of mine.