基于构建的隧道掌子面二维多块体滑移破坏模式，将非线性Hoek−Brown准则与软岩强度随饱和度变化关系相结合，借助极限分析原理和数值优化手段，提出一种在不同饱和度下估算隧道掌子面破坏范围的计算方法。以广西瑶寨隧道突水突泥事故作为算例，计算得到不同饱和度下隧道掌子面的破坏范围。研究结果表明：岩体的抗压强度随饱和度的提高逐渐减小，且通过参数转换得到的黏聚力与内摩擦角也随之减小；隧道掌子面破坏范围和支护力随饱和度的增大而增大；当饱和度为0.8时，破坏面已延伸至地表，此时维持掌子面稳定的最小支护压力为651.541 kPa；在破坏面扩大延伸的过程中，若不采取相应的处理措施，则隧道掌子面将产生突水突泥、塌方等地质灾害。该方法最大的优点是凭借少量的试验参数就能确定隧道掌子面的破坏范围，可作为隧道设计施工中的一种估算方法。%Based on the multi-blocks failure mechanism, a computing method for estimating the scale of the collapsing area of the tunnel face under different degrees of saturation was proposed by non-linear Hoek−Brown failure criterion and the relationship between the strength of soft rocks and saturation. Taking the accident of water gushing and mud outburst in Yaozhai Tunnel as an example, the scope of the collapsing area in the front of the tunnel face was computed under different degrees of saturation. The results show that the compressive strength of rock decreases gradually with the increase of the degree of saturation, so does the cohesion and internal friction angle which is obtained by the parameter transformation. However, both the scale of collapsing area of the tunnel face and the supporting forces tend to increase with the increase of the saturation. When the saturation is 0.8, the failure surface extends to the earth’s surface and the supporting force approaches 651.541 kPa. Moreover, some geological disasters such as water gushing, mud gushing and the landslides will occur if the failure surface extends without any protective measurement. The greatest advantage of this proposed method is that the range of the collapsing area of the tunnel face can be determined even based on a few experimental parameters, which can be regarded as a kind of estimating approach for tunnel design and construction.
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