Evaluating rock mass disturbance within open-pit excavations using seismic methods: A case study from the Hinkley Point C nuclear power station
Evaluating rock mass disturbance within open-pit excavations using seismic methods: A case study from the Hinkley Point C nuclear power station
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DOI：
10.1016/j.jrmge.2020.12.001
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发表时间：
2021-06-01
影响因子：
7.3
通讯作者：
Koe, Adrian
中科院分区：
文献类型：
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作者：
Butcher, Antony;Stork, Anna L.;Koe, Adrian
在进行大型挖掘项目时，了解岩石强度至关重要，因为准确的评估可确保安全且具有成本效益的工程边坡。在核电站等关键基础设施的建设过程中，平衡成本与安全的权衡变得更加必要，因为关键部件都建在相对较深的挖掘中。设计这些工程边坡依赖于岩石强度模型，这些模型通常使用在工程开始前测量的岩石特性（例如无侧限抗压强度、岩石扰动）的估计值进行参数化。然而，开挖的物理过程削弱了剩余的岩体。因此，该模型还需要对预期的岩石扰动进行调整。在实践中，这个参数很难量化，因此它往往受到很差的约束。这可能会对最终设计和挖掘成本产生重大影响。我们目前的被动和主动地震调查的结果，图像的范围和程度的干扰最近开挖的斜坡在欣克利角C核电站的施工现场。主动地震勘测的结果表明，扰动主要局限于距开挖面0.5 m的范围内。同时，被动监测被用来检测地震事件对应于断裂的厘米级和事件的位置是一致的0.5米的干扰到岩石面。这表明该地点的岩石扰动相对较低，并且发生在挖掘期间和之后。开挖前后记录的地震速度的比率被用来确定所需的Hoek-Brown岩石破坏准则的干扰参数，我们评估岩石干扰是低的干扰的幅度比预期更快地减少到开挖的斜坡。地震方法提供了一种低成本和快速的方法来评估与开挖相关的岩体扰动，这可以导致大型开挖项目的成本降低。(C)2021中国科学院岩土力学研究所。由爱思唯尔公司制作和主持
Understanding rock strength is essential when undertaking major excavation projects, as accurate assessments ensure both safe and cost-effective engineered slopes. Balancing the cost-safety trade-off becomes more imperative during the construction of critical infrastructure such as nuclear power stations, where key components are built within relatively deep excavations. Designing these engineered slopes is reliant on rock strength models, which are generally parameterised using estimates of rock properties (e.g. unconfined compressive strength, rock disturbance) measured prior to the commencement of works. However, the physical process of excavation weakens the remaining rock mass. Therefore, the model also requires an adjustment for the anticipated rock disturbance. In practice, this parameter is difficult to quantify and as a result it is often poorly constrained. This can have a significant impact on the final design and cost of excavation. We present results from passive and active seismic surveys, which image the extent and degree of disturbance within recently excavated slopes at the construction site of Hinkley Point C nuclear power station. Results from active seismic surveys indicate that the disturbance is primarily confined to 0.5 m from the excavated face. In conjunction, passive monitoring is used to detected seismic events corresponding to fracturing on the cm-scale and event locations are in agreement with 0.5 m of disturbance into the rock face. This suggests rock disturbance at this site is relatively low and occurred during and immediately after the excavation. A ratio of seismic velocities recorded before and after excavations are used to determine the disturbance parameter required for the Hoek-Brown rock failure criterion, and we assess that rock disturbance is low with the magnitude of the disturbance diminishing more quickly than expected into the excavated slope. Seismic methods provide a low-cost and quick method to assess excavation related rock mass disturbance, which can lead to cost reductions in large excavation projects. (C) 2021 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting by Elsevier B.V.