隧道掌子面前后方围岩爆破振动及精准控制研究
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U455.6

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国家自然科学基金资助项目(51978356,52108371);山东省自然科学基金资助项目(ZR2022ME043)


Study on Blasting Vibration and Precise Control of Surrounding Rock in Front and Rear of Long-Span Railway Tunnel Face
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    摘要:

    依托某大跨高速公路隧道工程,通过监测隧道下台阶爆破过程中围岩振动响应,对比分析了掌子面前后方围岩的振速和频谱特征;采用数值模拟方法,研究了不同围岩级别的掌子面前后方围岩爆破振速衰减规律。结果表明:掌子面前方围岩振速VZ>VX>VY,掌子面后方围岩振速VX>VY>VZ;掌子面前方Z向振速显著大于后方,而后方X、Y向振速显著大于前方,前后方振动特征差异的主要原因是爆源与测点的空间距离、传播介质及边界条件的不同所引起。由于掌子面后方已开挖隧洞空气层的减振效应,导致爆破地震波在后方传播过程中发生绕射和折射,使得后方围岩的合成振速要显著小于前方且衰减更加迅速,后方围岩的振动主频要显著低于掌子面前方,且后方频谱带宽窄于前方。拟合得到不同围岩级别的掌子面前后方围岩振速预测公式,并提出考虑空气减振系数的围岩爆破振速预测公式。根据隧道掌子面与下穿的既有管线的前后位置关系,分别运用前后方围岩爆破振速预测公式计算出前后方安全药量,实现了隧道穿越管线前后全过程的精准爆破振动控制,同时又极大提高施工效率。

    Abstract:

    Based on a long-span highway tunnel project, the velocity and spectral characteristics of the surrounding rock in the front and rear of the tunnel face were compared and analyzed by monitoring the response during the lower step of the tunnel blasting. The numerical simulation method was used to study the attenuation law of blasting vibration velocity in the front and rear of the surrounding rocks with different surrounding rock levels. The results showed that the velocity of surrounding rock ahead of the tunnel face was VZ>VX>VY, while the velocity of surrounding rock behind the palm face was VX>VY>VZ. The difference of the front and rear vibration characteristics of the tunnel face was due to the spacing distance between the explosion source and the measuring points, the difference of the propagation medium and the boundary conditions. Owing to the vibration reduction effect of the air isolation layer in the excavated tunnel behind the tunnel face, the diffraction and refraction of the blasting seismic wave occurred in the rear propagation process, and thus the resultant vibration velocity of the surrounding rock in the rear was significantly smaller than that in the front and decayed more rapidly. The vibration dominant frequency of the rear surrounding rock was significantly lower than that of the front of the tunnel face, and the rear spectrum bandwidth was narrower than that of the front. The prediction formula of vibration velocity of surrounding rock in the front and rear of the tunnel face with different surrounding rock levels was obtained by curve-fitting. The prediction formula of blasting vibration velocity of the surrounding rock was proposed by considering reduction coefficient of the air isolation layer. According to the relationship between the front and rear positions of the tunnel face and the existing pipelines, the safety charges of the front and rear were calculated by using the prediction formula of the blasting velocity of the front and the rear surrounding rock, respectively. The precise blasting vibration control of the whole process before and after the tunnel crossing the pipeline was realized and the construction efficiency was greatly improved.

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管晓明,宫哲,程飞,辛鲁超,吴庆东,范学臣.隧道掌子面前后方围岩爆破振动及精准控制研究[J].河北工程大学自然版,2023,(1):49-54,74

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  • 收稿日期:2022-12-11
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  • 在线发布日期: 2023-03-31
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