Extraction of image fractal characteristics of rock chips based on the Sandbox method and analysis of shield tunneling performance

IF 6.7 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Tunnelling and Underground Space Technology Pub Date : 2025-05-27 DOI:10.1016/j.tust.2025.106751

Changbin Yan , Yuxuan Shi , Zihe Gao , Weiwei Zhan

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引用次数: 0

Abstract

The size distribution of rock chips can fully reflect the performance of shield machine, and existing size distribution indicators suffer from low efficiency and poor accuracy. Therefore, the aim is to find an accurate and rapid quantitative indicator to characterize the rock chips size distribution and address the engineering issues of shield machine rock-breaking efficiency analysis and tunneling parameter optimization. In this study, five groups of rock chips with different quality components and eight shooting heights were designed to explore the performance and applicability of the image fractal dimension (D), a quantitative indicator of rock chip size distribution based on the Sandbox fractal method, and also to compare it with the traditional Box-counting method. Additionally, an analysis of 136 groups of rock chips data from different surrounding rock grades was conducted to investigate the correlation between image fractal dimension and common shield performance indexes, such as the average single cutter thrust force (F_n), and penetration depth (P_rev). The results indicate that the experimental platform constructed in this study, with image data acquired at a shooting height of 120 cm, is well-suited for calculating image fractal dimension. Compared to the traditional Box-counting method, the Sandbox method demonstrates higher sensitivity to changes in the particle size distribution of rock chips and does not impose restrictions on input image size, making it more appropriate for quantitative analysis. The image fractal dimension decreases as the proportion of large-sized rock chips increases. Under the same surrounding rock conditions, the image fractal dimension of rock chips is positively correlated with the logarithm of specific energy (SE) and negatively correlated with the logarithm of coarseness index (CI), effectively reflecting shield rock-breaking efficiency. Based on the correlation between image fractal dimension and SE, the optimal ranges of F_n and S/P_rev under grade II, III, IV, and V surrounding rock conditions can be determined, thereby enabling the optimization of tunneling performance.

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基于沙盒法的岩屑图像分形特征提取及盾构性能分析

岩屑粒度分布能充分反映盾构机的性能，现有粒度分布指标存在效率低、精度差的问题。因此，寻求一种准确、快速的定量指标来表征岩屑粒径分布，解决盾构机破岩效率分析和掘进参数优化的工程问题。本研究设计了5组不同质量成分、8个拍摄高度的岩屑，探讨了基于沙盒分形方法的岩屑尺寸分布定量指标图像分形维数(D)的性能和适用性，并与传统的Box-counting方法进行了比较。此外，通过对136组不同围岩等级的岩屑数据进行分析，探讨了图像分形维数与盾构常用性能指标（如平均单刀推力（Fn）、穿透深度（Prev））的相关性。结果表明，本研究所搭建的实验平台，拍摄高度为120 cm的图像数据，可以很好地用于图像分形维数的计算。与传统的Box-counting方法相比，Sandbox方法对岩屑粒度分布的变化具有更高的灵敏度，并且不受输入图像大小的限制，更适合于定量分析。图像分形维数随着大尺寸岩屑比例的增加而减小。在相同围岩条件下，岩屑图像分形维数与比能（SE）对数正相关，与粗度指数（CI）对数负相关，有效反映盾构破岩效率。根据图像分形维数与SE的相关性，可以确定II、III、IV、V级围岩条件下Fn和S/Prev的最优范围，从而实现掘进性能的优化。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Tunnelling and Underground Space Technology 工程技术-工程：土木

CiteScore

11.90

自引率

18.80%

发文量

454

审稿时长

10.8 months

期刊介绍： Tunnelling and Underground Space Technology is an international journal which publishes authoritative articles encompassing the development of innovative uses of underground space and the results of high quality research into improved, more cost-effective techniques for the planning, geo-investigation, design, construction, operation and maintenance of underground and earth-sheltered structures. The journal provides an effective vehicle for the improved worldwide exchange of information on developments in underground technology - and the experience gained from its use - and is strongly committed to publishing papers on the interdisciplinary aspects of creating, planning, and regulating underground space.