巷道浅层破碎围岩锚注加固承载特性试验研究

为明确巷道浅层破碎围岩锚注加固承载特性，开展了不同岩体粒径、岩性、锚杆数量等因素影响下对比试验。研究结果表明：（1）试件承载能力随粒径增大呈现先增大后减小的趋势，与相同条件下无锚试件相比，含锚试件峰值应力平均提高了53.38%，峰值应变平均减小了46.43%。（2）含锚条件下，与支护面相对的自由面及附近为宏观破裂优先发展区域，支护面破坏一般均滞后于自由面，试件由拉伸破坏为主，逐渐过渡到拉剪混合式破坏；无锚条件下，试件以拉伸破坏为主。（3）锚杆数量增加，试件承载能力逐渐增大，但是增长速率逐渐变缓，峰值应变减缓与峰值应力增长拐点一致。（4）试件具有渐进再破坏的3个特征：一是应力峰值前产生的裂纹在峰后阶段继续扩展；二是支护面表面材料随着裂纹拉伸产生剥落；三是裂纹由表面逐渐向试件内部发展，先是岩块脱落，随后宏观破坏发展到锚杆区域，造成试件整体承载能力丧失。

Experimental study on bearing characteristics of bolt-grouting support in shallow fractured surrounding rock of roadway

To clarify the bearing characteristics of bolt-grouting support in shallow fractured surrounding rock of roadway, comparative bolt-grouting bearing capacity test was carried out with different rock particle sizes, lithologies, and number of bolts. The results show that: 1) the bearing capacity of the bolt-grouting increases first and then decreases with increasing the particle size. Compared with the non-anchored specimens under the same conditions, the peak stress of the anchored specimens increases by 53.38% on average, and the peak strain decreases by 46.43% on average. 2) Under anchored condition, the free surface opposite to the supporting surface and its vicinity are the preferred area for macro-fracture development. The failure of supporting surface generally lags behind the free surface, and the specimens gradually transit from mainly tensile failure to tensile-shear mixed failure; tensile failure is the main failure mode of specimens under the condition of no anchor. 3) With the increase of bolt number, the bearing capacity of bolt-grouting increases gradually, but the growth rate slows down gradually. The peak strain slows down, which is consistent with the inflection point of peak stress growth. 4) The specimens have three characteristics of progressive destruction: firstly, the cracks generated before peak stress continue to propagate after peak stress; secondly, the surface material of support surface spalls with the crack stretching; thirdly, the cracks gradually develop from surface to inside of the specimens, the rock fragments fall off first, and then the macro-damage develops to the anchor area, resulting in the loss of overall specimen bearing capacity.