The stress concentration and failure at chamber intersections in coal mine are intense, especially in deep-buried, super-large section conditions. In this paper, the plastic radius of super-large section chamber under unequal pressure was corrected on the basis of the size effect. Then, stress and failure evolution of intersections under different crossing angles and equivalent angular bisectors were revealed. Furthermore, 2 trajectory curves of failure and stress were analytically expressed, which divided the intersection into 5 influencing zones in the light of stress superposition degree. After determining instability trigger point and instability path, instability energy criterion of intersection can be obtained as K > 1, which means that the external energy is greater than the sum of energy consumed by surrounding rock instability and supporting structure failure. Taking coal-gangue separation system of Longgu Coal Mine as example, it was found that there was instability risk under original parameters. For long-term stability, an optimization design method was proposed by considering safety factor, and optimal support scheme was obtained. Field monitoring showed intersections deformations were relatively small with the maximum of 125 mm, which verified the rationality of theoretical analysis. This study provides guidance for the stability control of the intersections under the same or similar conditions.

煤矿井筒交叉口处应力集中和破坏强烈，特别是在深埋、超大断面条件下。本文基于尺寸效应对不等压超大截面室的塑性半径进行修正。然后，揭示了不同交叉角和等效角平分线下交叉口的应力和失效演变。进一步分析表达了2条失效和应力轨迹曲线，根据应力叠加程度将交叉点划分为5个影响区。确定失稳触发点和失稳路径后，可得到交点失稳能量判据为K > 1，表示外来能量大于围岩失稳与支护结构破坏所消耗能量之和。以龙固煤矿煤矸石分离系统为例，发现在原有参数下存在失稳风险。针对长期稳定性，提出了一种考虑安全系数的优化设计方法，得到了最优的支护方案。现场监测显示交叉口变形较小，最大为125 mm，验证了理论分析的合理性。本研究为相同或相似条件下交叉口的稳定性控制提供指导。