大松动圈围岩锚网索联合支护参数确定方法探讨

对大松动圈围岩巷道，单一锚杆支护难以实现对整个破裂区围岩的锚固控制，采用锚网索联合支护时，应考虑锚杆支护对联合支护设计的作用。通过分析大松动圈围岩锚杆锚固支护机制，提出量化锚杆支护作用的锚固承载系数，形成锚网索联合支护参数量化计算方法。研究结果表明：锚杆锚固支护后将大松动圈围岩分为浅层锚固区和深层破裂区，浅层锚固区具有一定承载能力，可视作锚索的等效托盘；在锚网索联合支护中，浅层锚固区承载结构稳定的条件是锚固结构承载力大于环向轴力且能够有效控制破裂区围岩；锚固承载系数大小主要取决于浅层锚固区与破裂区和锚杆预紧力与设计锚固力的关系，对于大松动圈围岩其取值范围为0.45～0.75。经现场试验可知，巷道顶底板移近量为273 mm，两帮移近量为393 mm，表面位移曲线趋于平稳，采用该方法得到的锚网索支护参数有效保证了巷道的正常使用。

Discussion on determination method of anchor-net-cable coupling support parameters of surrounding rock in a large broken zone

Anchor-net-cable coupling support is widely used in roadways and particularly in large broken zones. Since the anchor is not long enough to support the whole range of surrounding rock in a large broken zone, it should consider the influence of anchor support on the design of a combined supporting when using the anchor-net-cable coupling support. Through systematically analyzing the support mechanism of surrounding rock bolt anchorage in large broken zones, the bolt supporting of anchorage bearing coefficient is proposed. Then, a calculation method to quantitatively determine parameters for anchor-net-cable coupling support is derived. The results show that the strong fractured surrounding rocks are divided into a shallow anchored zone and a deep fracture zone. The former can bear part of the surrounding rock as the cable-pallet, and its stability condition when the bearing capacity is greater than the axial force and the fracture zone is effectively controlled. The bearing coefficient of an anchor is in the range of 0.45-0.75 for the large broken zone, which is depending on the anchorage zone, fracture zone, anchor pre-tightening force and anchoring force. In the field test, the convergences of roof-to-floor and two walls are 273 mm and 393 mm, respectively, and the surface displacement tends to be stable. The proposed method for determination of parameters of anchor-net-cable coupling support effectively ensures its regular applications to the roadways.