公路隧道差异化爆破施工与损伤控制研究

Study on Differential Blasting Excavation and Damage Control of Highway Tunnel

莆炎高速公路隧道YA18标段钻爆法施工时,针对该区域地质条件复杂、岩性变化大的特点,提出差异化爆破设计与施工方案。对于Ⅲ级围岩采用二级楔形掏槽、周边光面爆破的形式,分台阶开挖;Ⅳ级围岩采用楔形掏槽、周边预裂爆破的形式,环形开挖预留核心土;Ⅴ级围岩采用楔形掏槽、周边预裂爆破的形式,中隔壁法开挖。通过采用差异化爆破施工方法,有效控制围岩爆破损伤并减小超欠挖现象,开挖轮廓平整,Ⅲ级围岩半眼痕保留率在90%以上,从而降低隧道支护及相关成本。隧道爆破振动强度位于合理区间范围内,保证周围建(构)筑物的安全。实践证明差异化爆破施工方法对地质条件的适应性强,具有显著的经济效益和社会价值,值得在类似工程中推广应用。

Aiming at the characteristics of complex geological conditions and large lithological changes in the drilling and blas-ting method of the YA18 section of the Puyan Expressway Tunnel,a differential blasting scheme was proposed.For GradeⅢsurrounding rocks,wedge-level trenching is used,and the surrounding surface is smooth blasting,and the steps are excavated in steps.GradeⅣsurrounding rock is using wedge-shaped trenching,and the surrounding pre-splitting blasting form is used to excavate the core soil in a circular shape.The rock adopts wedge-shaped notch,peripheral pre-splitting blasting,and exca-vation by the middle wall method.By adopting the differential blasting construction method,the surrounding rock damage in-duced by blasting is effectively controlled,and the phenomenon of over-excavation is reduced.The excavation contour is flat,and the half-eye mark retention rate of the GradeⅢsurrounding rock is more than 90%,which reduces the tunnel support and related cost.The blasting vibration intensity of the tunnel is located in a reasonable range,ensuring the safety of surrounding buildings(structures).Practice has proved that differential blasting has strong adaptability to geological conditions,has sig-nificant economic benefits and social value,and is worthy of application and popularization in similar projects.