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首页> 外文期刊>Tunnelling and underground space technology >Prediction of blast-induced overbreak from uncontrolled burn-cut blasting in tunnels driven through medium rock class
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Prediction of blast-induced overbreak from uncontrolled burn-cut blasting in tunnels driven through medium rock class

机译：通过中等岩石等级驱动的隧道中不受控制的燃烧切割爆破引起的爆炸诱发的超前预报

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Drilling and blasting is the predominant rock excavation technique in driving horizontal tunnels. This often results in large overbreak. One of the prime reasons for overbreak is the unacceptable levels of ground vibration generated in blasting. From the literature survey and practical experience, it was found that threshold levels of PPV for overbreak depends on rock properties, namely, rock strengths, P-wave velocity, specific gravity, Poisson's ratio and rockmass parameters. Determination of threshold level of peak particle velocity (PPV) is crucial for controlling blast-induced overbreak and can be approximated by extrapolating the vibration predictor established from near-field vibration monitoring. This paper reports the experiments carried out in five horizontal tunnels for monitoring near-field ground vibration using accelerometer-based-seismograph planted in roof/sidewalls to establish ground vibration predic tors. Blast-induced overbreak for each blast has been measured using a telescopic profiler. The threshold levels of PPV for overbreak have been estimated from the extrapolated vibration predictors to the over-break zone and also using near field approximation technique. The estimated threshold levels of PPV for overbreak ranged between 590 and 1050 mm/s in extrapolation model and 410-890 mm/s in near-field HP model. Apart from these, a relationship between the percentage overbreak and rock/rockmass, charge and blast design parameters has been established through multivariate regression analysis of the data pertaining to five investigating sites. The result has been validated for four blasts within reasonable accuracy.
机译：钻探和爆破是驱动水平隧道的主要岩石开挖技术。这通常会导致大量爆发。爆炸的主要原因之一是爆破过程中产生的地面振动不可接受。从文献调查和实践经验中发现，PPV的爆发阈值水平取决于岩石特性，即岩石强度，P波速度，比重，泊松比和岩石质量参数。确定峰值粒子速度（PPV）的阈值水平对于控制爆炸引起的爆发至关重要，可以通过外推从近场振动监测中建立的振动预测器来估算。本文报告了在五个水平隧道中进行的实验，这些地震使用安装在屋顶/侧壁中的基于加速度计的地震仪监测近场地面振动，以建立地面振动预测因子。使用伸缩式轮廓仪测量了每次爆炸的爆炸诱发爆发。从外推的振动预测器到突围区域，并使用近场近似技术，估计了突围的PPV阈值水平。在外推模型中，估计的PPV爆发阈值水平介于590和1050 mm / s之间，在近场HP模型中，估计为410-890 mm / s之间。除此之外，通过对涉及五个调查地点的数据进行多元回归分析，建立了突围百分比与岩石/岩体，装药和爆炸设计参数之间的关系。该结果已在合理的精度范围内验证了四次爆炸。

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