Engineering Geology最新文献_第6页

Numerical investigation of the fast shear behaviour of granular materials and its significance for rapid landslides 颗粒材料快速剪切行为的数值研究及其对快速滑坡的意义

IF 6.9 1区工程技术 Q1 ENGINEERING, GEOLOGICAL

Engineering Geology

Pub Date : 2024-09-26 DOI: 10.1016/j.enggeo.2024.107733

Chenhui Du , Jianqi Zhuang , Jianbing Peng , Jiaxu Kong , Wei Hu

The shear behaviour of granular materials at high velocities is crucial for understanding the high mobility of rapid landslides and the low-friction mechanisms behind them. Here, a numerical ring shear model driven by granular shear platens was developed, and this model was validated in terms of the kinematics and mechanics of the granular material. The granular material was then accelerated at different accelerations to high shear velocities (ranging from 0.001 m/s to a maximum of 5.0 m/s). The results indicate that with increasing shear velocity, the shear behaviour of granular materials transitions from a single behaviour to a composite behaviour. The composite shear behaviour is important for both the shear flow state and the frictional characteristics. The velocity profile reveals the transition of granular materials from uniform shear flow to composite shear flow consisting of locally high-shear-rate layers and slow creep layers; the volume of granular materials transitions from global expansion at the onset of shearing to local expansion; and particle velocity fluctuations and contact force fluctuations change from being uniformly distributed and relatively small at the beginning of shearing to rapid growth in local areas. Furthermore, with increasing shear velocity, the frictional characteristics become nonuniform. Local areas exhibit positive velocity-related friction effects, whereas the friction of the particles in other regions slightly decreases. Particle fluctuations represent an important factor that leads to the composite shear behaviour of granular materials. This study provides valuable insights into the shear behaviour of particles in rapid landslides.

颗粒材料在高速下的剪切行为对于理解快速滑坡的高流动性及其背后的低摩擦机制至关重要。在此，我们建立了一个由颗粒剪切压板驱动的环形剪切数值模型，并从颗粒材料的运动学和力学角度对该模型进行了验证。然后以不同的加速度将颗粒材料加速到高剪切速度（从 0.001 m/s 到最高 5.0 m/s）。结果表明，随着剪切速度的增加，颗粒材料的剪切行为会从单一行为过渡到复合行为。复合剪切行为对剪切流动状态和摩擦特性都很重要。速度剖面显示了颗粒材料从均匀剪切流过渡到由局部高剪切速率层和慢蠕变层组成的复合剪切流；颗粒材料的体积从剪切开始时的整体膨胀过渡到局部膨胀；颗粒速度波动和接触力波动从剪切开始时的均匀分布和相对较小转变为局部区域的快速增长。此外，随着剪切速度的增加，摩擦特性也变得不均匀。局部区域表现出与速度相关的正摩擦效应，而其他区域的颗粒摩擦力则略有下降。颗粒波动是导致颗粒材料复合剪切行为的一个重要因素。这项研究为快速滑坡中颗粒的剪切行为提供了宝贵的见解。

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引用次数: 0

Assessment of seabed trench formation based on marine sediment properties and chain-bar penetration tests 根据海洋沉积物特性和链条穿透测试评估海底海沟的形成

IF 6.9 1区工程技术 Q1 ENGINEERING, GEOLOGICAL

Engineering Geology

Pub Date : 2024-09-26 DOI: 10.1016/j.enggeo.2024.107746

Shengjie Rui , Hans Petter Jostad , Zefeng Zhou , Lizhong Wang , Svein Sævik , Yufei Wang , Zhen Guo

Seabed trenches, as a geological hazard, adversely influence the safety of adjacent anchors. Seabed trenches predominantly appear in the Gulf of Guinea, where the seabed soils exhibit some features, e.g., high plasticity, high water content and low shear strength. However, the marine engineering geology where seabed trenches appear is not well understood, as well as the trenching process related to soil erosion. In this paper, the information about seabed trenches was summarized, and marine engineering geology where seabed trenches appear was analyzed in detail. It was found that the marine clay with high plasticity index, high organic content, higher sensitivity, low effective unit weight and shear strength is easier to form seabed trenches. Then, penetration tests of a chain-bar penetrometer were conducted to investigate the soil deformation and erosion near the surface. Experimental observations reveal that the normalized soil resistances from both penetrometers exhibited similar trends, despite different soil deformation mechanisms. In the cyclic tests, the soil resistance was degraded significantly in the first 20 cycles, and water flow induced by chain motion eroded the soil particles near the chain links. This study provides insights into the marine engineering geology and development process of seabed trenches.

海底壕沟作为一种地质灾害，对邻近锚地的安全产生不利影响。海底壕沟主要出现在几内亚湾，那里的海底土壤呈现出一些特征，例如高塑性、高含水量和低剪切强度。然而，人们对出现海底海沟的海洋工程地质以及与土壤侵蚀有关的海沟形成过程了解不多。本文总结了有关海底海沟的信息，并对出现海底海沟的海洋工程地质进行了详细分析。研究发现，塑性指数高、有机质含量高、灵敏度高、有效单位重和剪切强度低的海洋粘土更容易形成海底沟槽。然后，用链条式贯入仪进行了贯入试验，以研究近地表的土壤变形和侵蚀情况。实验结果表明，尽管土壤变形机制不同，但两种贯入仪的归一化土壤阻力表现出相似的趋势。在循环测试中，土壤电阻在前 20 个循环中显著下降，链条运动引起的水流侵蚀了链节附近的土壤颗粒。这项研究为海洋工程地质学和海底沟槽的开发过程提供了启示。

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引用次数: 0

Coupling stress and transmissivity to define equivalent directional hydraulic conductivity of fractured rocks 耦合应力和透射率，确定裂隙岩的等效定向导水性

IF 6.9 1区工程技术 Q1 ENGINEERING, GEOLOGICAL

Engineering Geology

Pub Date : 2024-09-26 DOI: 10.1016/j.enggeo.2024.107739

C. Darcel , R. Le Goc , E. Lavoine , P. Davy , D. Mas Ivars , E. Sykes , H.A. Kasani

A DFN (Discrete Fracture Network) modelling approach is developed to couple stresses with fracture transmissivities and to evaluate large scale rock mass hydraulic conductivity. The transmissivity-stress coupling relies on a negative exponential correlation between normal stress acting on a fracture and fracture transmissivity, bounded by residual and maximal apertures. The remote stresses and the local stress fluctuations induced by the fractures themselves are combined in a semi-analytical approach to compute the normal stress acting on each fracture of a DFN. Directional equivalent hydraulic conductivities are numerically computed in all directions from a spherical permeameter setup. The resulting properties are first a cloud of points, where each point defines a direction and an equivalent hydraulic conductivity. The distribution of equivalent hydraulic conductivities is analyzed to define mean values, preferential directions and anisotropy ratio. The entire workflow is developed in the numerical platform DFN.lab. The capacity of the method to investigate the impact of the in-situ stresses on the rock mass hydraulic conductivity is illustrated for fracturing and in-situ stress conditions similar to the conditions at the Forsmark site in Sweden. We find that the stress fluctuations induced by the fractures have a significant impact on the resulting hydraulic conductivity field. They limit the anisotropy ratio to values close to a factor of 3 while the transmissivity distribution is correlated to orientations and spans several orders of magnitude. Sensitivity analyses, performed by changing the parameters of the transmissivity-stress law, show quantitatively how the directional hydraulic conductivities are rather controlled by the orientations of the in-situ stresses or by the underlying connectivity structure of the DFN.

我们开发了一种 DFN（离散断裂网络）建模方法，用于将应力与断裂透射率耦合，并评估大尺度岩体的导水性。透射率-应力耦合依赖于作用在断裂上的法向应力与断裂透射率之间的负指数相关性，以残余孔隙和最大孔隙为界。通过半分析方法，将远距离应力和断裂本身引起的局部应力波动结合起来，计算出作用在 DFN 每条断裂上的法向应力。根据球形渗透仪的设置，对所有方向的等效导流系数进行数值计算。计算结果首先是一个点云，其中每个点定义了一个方向和一个等效水力传导率。通过分析等效水力传导率的分布，确定平均值、优先方向和各向异性比。整个工作流程是在数值平台 DFN.lab 中开发的。针对与瑞典 Forsmark 现场条件类似的压裂和原位应力条件，说明了该方法研究原位应力对岩体导水性影响的能力。我们发现，裂缝引起的应力波动对所产生的导水性场有重大影响。它们将各向异性比限制在接近 3 倍的数值，而渗透率分布则与方向相关，并跨越几个数量级。通过改变透射率-应力定律的参数进行的敏感性分析，定量地显示了定向导水性是如何受到原位应力方向或 DFN 潜在连通结构的控制的。

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引用次数: 0

Characterization of the active fault deformation zone of the Chegualin Fault in the alluvial plain of southwestern Taiwan 台湾西南部冲积平原车瓜林断层活动断层变形带的特征分析

IF 6.9 1区工程技术 Q1 ENGINEERING, GEOLOGICAL

Engineering Geology

Pub Date : 2024-09-25 DOI: 10.1016/j.enggeo.2024.107740

Chuan Ding , Jia-Jyun Dong , Maryline Le Béon , Cheng-Chao Lee , Shu-Ken Ho , Sheng-Tsung Wang

The activity of a creeping active fault poses significant challenges to engineering structures due to surface deformation. Therefore, quantifying the strain concentration caused by an active fault, delineating the extent and location of the Active Fault Deformation Zone (AFDZ), estimating long-term deformation trends, and predicting future deformations are crucial in the field of engineering geology.

This study comprehensively integrates multi-timescale analytical methods by incorporating detailed geodetic data, rupture surveys, morphotectonic analysis, geological borehole data, biochronological data, radiocarbon dating, and Holocene uplift rate analysis to identify or confirm the locations of active faults and the long-term evolution trends of active deformation zones. Based on our findings, three active fault planes are identified, with one possibly being the main fault with the highest activity. Furthermore, by comparing long-term deformation rates derived from isochrone lines with short-term deformation rates obtained from leveling, we observe a risk of slip rate deficit. These findings have significant implications for engineering geology. As a general contribution, our study can serve as a site screening strategy for similar locations. Regarding the infrastructure we targeted, we provide critical input parameters for further numerical models (such as the trishear model) to simulate surface deformation, and offer essential design parameters for structures. Considering potential coseismic deformation on the investigated fault, these results are fundamental for future investigations or mitigation plans.

由于地表变形，蠕动活动断层的活动给工程结构带来了巨大挑战。因此，量化活动断层引起的应变集中、划定活动断层变形区（AFDZ）的范围和位置、估计长期变形趋势以及预测未来变形是工程地质领域的关键。本研究综合运用详细的大地测量数据、断裂调查、形态构造分析、地质钻孔数据、生物年代学数据、放射性碳年代测定和全新世隆起率分析等多尺度分析方法，确定或确认了活动断层的位置和活动变形带的长期演化趋势。根据我们的研究结果，确定了三个活动断层面，其中一个可能是活动最频繁的主断层。此外，通过比较等时线得出的长期变形率和水准测量得出的短期变形率，我们发现存在滑移率不足的风险。这些发现对工程地质具有重要意义。作为一般贡献，我们的研究可作为类似地点的选址策略。关于我们所针对的基础设施，我们为进一步的数值模型（如三剪切模型）模拟地表变形提供了关键的输入参数，并为结构提供了重要的设计参数。考虑到所调查断层的潜在共震变形，这些结果对于未来的调查或缓解计划至关重要。

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引用次数: 0

Sediment stacking pattern effect on sand liquefaction inferred from full-scale experiments in the Emilia alluvial plain (Italy) 从意大利艾米利亚冲积平原的全面试验中推断沉积物堆积模式对砂土液化的影响

IF 6.9 1区工程技术 Q1 ENGINEERING, GEOLOGICAL

Engineering Geology

Pub Date : 2024-09-23 DOI: 10.1016/j.enggeo.2024.107735

Luca Minarelli , Daniela Fontana , Stefano Lugli , Kyle M. Rollins , Marco Stefani , Laura Tonni , Sara Amoroso

The geometry and the depositional configuration of sand bodies affected by the 2012 Emilia earthquakes (Bondeno site, northern Italy) were reconstructed and the role of the sediment stacking pattern was tested using data from full-scale blast experiments. The research integrates remote sensing and surface geological mapping, subsurface investigations including stratigraphic coring and cone penetration tests, grain-size and petrography of sands, geotechnical and geophysical monitoring. Data are compared with the Mirabello blast test site, also in the epicentral area. The results highlight the preeminent role of sediment heterogeneity and their mechanical and compositional properties in modulating liquefaction in alluvial settings. The lateral confinement of the buried sandy bodies, their thickness, and the occurrence of a thick non-liquefiable crust influence the dissipation of the excess pore water pressure, as indicated by the blast monitoring, and therefore the duration of liquefaction phenomena, according to the local stratigraphic architecture.

该研究重建了受 2012 年艾米利亚地震（意大利北部邦德诺遗址）影响的沙体的几何形状和沉积构造，并利用全尺寸爆破实验数据检验了沉积物堆积模式的作用。研究综合了遥感和地表地质绘图、地层取芯和锥入试验等地下调查、砂的粒度和岩相学、岩土工程和地球物理监测。数据与同样位于震中地区的米拉贝罗爆炸试验场进行了比较。结果凸显了沉积物的异质性及其机械和成分特性在调节冲积环境液化中的重要作用。正如爆破监测所显示的那样，埋藏的砂质体的横向限制、其厚度以及是否存在厚的不液化地壳会影响过大的孔隙水压力的消散，从而根据当地的地层结构影响液化现象的持续时间。

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引用次数: 0

Experimental study on the influence of rock pore structure on pressure stimulated voltage variations based on nuclear magnetic resonance 基于核磁共振的岩石孔隙结构对压力刺激电压变化影响的实验研究

IF 6.9 1区工程技术 Q1 ENGINEERING, GEOLOGICAL

Engineering Geology

Pub Date : 2024-09-23 DOI: 10.1016/j.enggeo.2024.107736

Shan He , Min Li , Shiliang Shi , Yi Lu , Deming Wang

Since rocks will generate voltage under load, studying their voltage characteristics is of prime importance for the prevention and control of mine dynamic disasters and the corresponding secondary disasters. In this study, a pressure stimulated voltage (PSV) test system for rock materials under uniaxial compression was constructed to explore the law of PSV variations of rocks. Meanwhile, a nuclear magnetic resonance test system was employed for investigating the influence mechanism of pore structure changes on PSV variations. The following beneficial results were obtained. A “double-peak” phenomenon is observed on the PSV curves of granite and sandstone, whereas, for marble, the phenomenon only appears under high loading rates. The T₂ spectra of different types of rock differ greatly. After granite fractures under load, some primary micro-pores are converted into meso-pores and macro-pores, accompanied by the generation of substantial new micro-pores. These micro-pores activate more rock defects (dislocation and grain boundary), resulting in a higher average PSV and peak PSV. After marble fractures, numerous primary micro-pores are transformed into meso-pores and macro-pores, and the proportion of new micro-pores falls. Consequently, its electricity generation capacity weakens. In contrast, sandstone contains a higher proportion of micro-pores. After it fractures, despite the conversion of some micro-pores into meso-pores and macro-pores, abundant micro-pores are generated again, bringing about a relatively high voltage. In short, the changes in overall porosity cannot represent the electricity generation capacity of rock, and the changes in bound cracks exert a profoundly influence on it. The key to the electricity generation capacity of rock lies in the increase and connection of micro-cracks.

岩石在载荷作用下会产生电压，因此研究岩石的电压特性对防治矿山动力灾害及相应的次生灾害具有重要意义。本研究构建了岩石材料在单轴压缩条件下的压力激励电压（PSV）测试系统，以探索岩石 PSV 的变化规律。同时，采用核磁共振测试系统研究孔隙结构变化对 PSV 变化的影响机理。取得了以下有益成果。花岗岩和砂岩的 PSV 曲线上出现了 "双峰 "现象，而大理石只有在高加载速率下才出现这种现象。不同类型岩石的 T2 光谱差异很大。花岗岩在荷载作用下断裂后，一些原生微孔转化为中孔和大孔，同时产生大量新的微孔。这些微孔激活了更多的岩石缺陷（位错和晶界），导致更高的平均 PSV 和峰值 PSV。大理石断裂后，大量原生微孔转变为中孔和大孔，新微孔的比例下降。因此，其发电能力减弱。相比之下，砂岩的微孔比例较高。断裂后，尽管部分微孔转化为中孔和大孔，但仍会重新产生丰富的微孔，从而带来相对较高的电压。总之，整体孔隙率的变化并不能代表岩石的发电能力，而束缚裂隙的变化对其影响深远。岩石发电能力的关键在于微裂隙的增加和连接。

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引用次数: 0

Insights from tensile fracture properties and full-field strain evolution of deep coral reef limestone under dynamic loads 从动态载荷下深层珊瑚礁石灰岩的拉伸断裂特性和全场应变演变中窥见一斑

IF 6.9 1区工程技术 Q1 ENGINEERING, GEOLOGICAL

Engineering Geology

Pub Date : 2024-09-23 DOI: 10.1016/j.enggeo.2024.107738

Kai Wu , Qingshan Meng , Hongya Li , Jiajun Deng , Haifeng Liu , Chi Wang , Le Luo , Tianli Shen

Coral reef limestone (CRL) commonly undergoes dynamic tension when underground structures of island reefs encounter impacts, explosions, or seismic activities. Given the complexity of biological pores, the dynamic tensile fracture characteristics of CRL are poorly understood. Therefore, the dynamic tensile fracture behaviors of deep CRL were systematically observed by Split Hopkinson Pressure Bar tests and digital image techniques. Comparing to traditional rocks, the macro-pores near failure band would significantly change cracking path. The failure patterns are dominated by loading rate. The strongly dependence of dynamic tensile strength and dynamic crack initiation toughness on loading rate suggests the two indices overcome the effect of CRL macro-pores under dynamic impacts. At low loading rates, tensile fractures predominantly follow intergranular cracks, whereas transgranular cracks dominate at higher rates. The fractal dimension of fracture surface decreases with increasing crack propagation velocity, loading rate, and dynamic crack initiation toughness. Due to the unique marine sedimentary environment, the mechanical heterogeneity in multiple scales distinguishes CRL from terrestrial rock materials. The insights into underlying mechanisms of dynamic tension provide support to optimization of blasting scheme and stability assessments for island underground engineering.

当岛礁的地下结构遭遇撞击、爆炸或地震活动时，珊瑚礁石灰岩（CRL）通常会发生动态拉伸。由于生物孔隙的复杂性，人们对珊瑚礁石灰岩的动态拉伸断裂特征知之甚少。因此，通过分体式霍普金森压杆试验和数字图像技术，对深层 CRL 的动态拉伸断裂行为进行了系统观测。与传统岩石相比，破坏带附近的大孔隙会显著改变开裂路径。破坏模式受加载速率的影响。动态抗拉强度和动态裂纹起始韧度与加载速率密切相关，这表明这两个指标克服了 CRL 大孔隙在动态冲击下的影响。在低加载速率下，拉伸断裂主要是晶间裂纹，而在较高加载速率下则主要是跨晶裂纹。断裂面的分形维度随着裂纹扩展速度、加载速率和动态裂纹起始韧性的增加而减小。由于独特的海洋沉积环境，多种尺度的力学异质性使 CRL 有别于陆地岩石材料。对动态张力基本机制的深入研究为优化爆破方案和海岛地下工程的稳定性评估提供了支持。

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引用次数: 0

Predicting cyclic liquefaction behavior of saturated granular materials using an updated state evolution model 利用最新状态演变模型预测饱和颗粒材料的循环液化行为

IF 6.9 1区工程技术 Q1 ENGINEERING, GEOLOGICAL

Engineering Geology

Pub Date : 2024-09-21 DOI: 10.1016/j.enggeo.2024.107731

Lihong Tong , Li Fu , Haibin Ding , Changjie Xu , C.W. Lim

Liquefaction and dynamic response of granular materials under dynamic loading has been studied intensively in field and laboratory tests. However, theoretical modeling and analytical solutions on liquefaction are still lagging and investigations are mostly restricted to laboratory observations. To investigate undrained liquefaction shear deformation and fluidity of granular material, the updated state evolution model is proposed by introducing an excess pore water pressure ratio parameter. A series of undrained cyclic triaxial tests and DEM simulations are conducted to verify the proposed model. The result indicates that the liquefaction behavior of granular materials can be captured by the updated state evolution model both at constant and varying loading frequency. Furthermore, the state parameter based on the deviatoric strain and excess pore water pressure ratio is determined to quantify assess the fluidity of granular materials. It facilitates the refinement of the discriminative criteria for cyclic liquefaction of granular materials. This parameter increases slowly at the beginning of loading, followed by a rapid and fluctuating rise, and reaches the peak before the initial liquefaction. Another significant finding is that the turning point of the state parameter range from 0.89 to 0.95 in the

θ - t / t_{0}

plane and between 0.84 and 0.94 in the

θ - r_{u}

plane, as affected by the cyclic loading conditions.

在现场和实验室试验中，对颗粒材料在动态荷载作用下的液化和动态响应进行了深入研究。然而，有关液化的理论建模和分析解决方案仍然滞后，研究大多局限于实验室观测。为了研究颗粒材料的排水液化剪切变形和流动性，通过引入过剩孔隙水压力比参数，提出了更新的状态演化模型。为了验证所提出的模型，进行了一系列不排水循环三轴试验和 DEM 模拟。结果表明，更新后的状态演化模型可以捕捉到恒定加载频率和变化加载频率下颗粒材料的液化行为。此外，还确定了基于偏离应变和过剩孔隙水压力比的状态参数，以量化评估颗粒材料的流动性。这有助于完善颗粒材料循环液化的判别标准。该参数在加载开始时缓慢上升，随后快速波动上升，并在初始液化前达到峰值。另一个重要发现是，受循环加载条件的影响，状态参数的转折点在 θ-t/t0 平面上介于 0.89 至 0.95 之间，在 θ-ru 平面上介于 0.84 至 0.94 之间。

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引用次数: 0

Fatigue mechanical properties and Kaiser effect characteristics of the saturated weakly cemented sandstone under different loading rate conditions 不同加载速率条件下饱和弱胶结砂岩的疲劳力学性能和凯撒效应特征

IF 6.9 1区工程技术 Q1 ENGINEERING, GEOLOGICAL

Engineering Geology

Pub Date : 2024-09-21 DOI: 10.1016/j.enggeo.2024.107732

Kui Zhao , Youbing Liu , Daoxue Yang , Bo Li , Zhen Huang , Chongjie Huang , Botan Shen , Xiongdong Lan

Weakly cemented sandstone (WCS) is a unique rock type widely distributed on the surface. Environmental factors such as groundwater and stress variations easily influence its fatigue mechanical properties and fracture characteristics. To design and evaluate the long-term stability of surrounding rock support in tunnel excavation and underground resource mining projects, investigating the fatigue mechanical properties and acoustic emission (AE) response characteristics of saturated WCS under different loading rates is of great practical and theoretical significance. This study employed experimental techniques such as X-ray diffraction (XRD), nuclear magnetic resonance (NMR), and natural water absorption tests to investigate the mineral composition, pore size, and connectivity characteristics of WCS. The multi-level cyclic loading-unloading tests (MCLU) combined with the AE system were conducted on dry and saturated WCS specimens at different loading rates. The results reveal that the deformation modulus of these specimens initially increases and then decreases under cyclic loading conditions. Water significantly influences the fatigue strength and deformation resistance of sandstone. As the loading rate increases, the range of RA values broadens, accompanied by a marked increase in the number of AE signals with high RA values. Saturated sandstone specimens are more prone to developing macroscopic shear fracture surfaces. Water has a more substantial effect on the stress distribution ranges corresponding to the response of the Kaiser effect in WCS than loading rates. The capacity of the Kaiser effect to indicate the extent of rock damage is intricately linked to the progression of internal micro-cracks. When internal damage surpasses the critical value of the Kaiser effect memory damage, the accelerated propagation of shear cracks becomes pivotal in the internal damage of the sandstone. It seems that the presence of water within the interior of the rock may facilitate the dissolution of K-feldspar in WCS, which could result in the formation of kaolinite, which will be further transformed into illite. The hydration expansion of illite may further exacerbate the deterioration effect of the mechanical properties of WCS.

弱胶结砂岩（WCS）是一种广泛分布于地表的独特岩石类型。地下水和应力变化等环境因素容易影响其疲劳力学性能和断裂特征。为设计和评价隧道开挖和地下资源开采工程中围岩支护的长期稳定性，研究饱和弱胶结砂岩在不同加载速率下的疲劳力学性能和声发射（AE）响应特性具有重要的现实意义和理论意义。本研究采用 X 射线衍射 (XRD)、核磁共振 (NMR) 和天然吸水试验等实验技术，研究了 WCS 的矿物成分、孔隙大小和连通性特征。在不同加载速率下，对干燥和饱和的 WCS 试样进行了多级循环加载-卸载试验（MCLU），并结合 AE 系统进行了试验。结果表明，在循环加载条件下，这些试样的变形模量先增大后减小。水对砂岩的疲劳强度和抗变形能力有很大影响。随着加载速率的增加，RA 值的范围也随之扩大，同时具有高 RA 值的 AE 信号数量也明显增加。饱和砂岩试样更容易出现宏观剪切断裂面。与加载速率相比，水对 WCS 中凯撒效应响应所对应的应力分布范围的影响更大。凯撒效应显示岩石破坏程度的能力与内部微裂缝的发展密切相关。当内部破坏超过凯撒效应记忆破坏的临界值时，剪切裂缝的加速扩展就成为砂岩内部破坏的关键。看来，岩石内部水的存在可能会促进 K 长石在 WCS 中的溶解，从而形成高岭石，并进一步转化为伊利石。伊利石的水化膨胀可能会进一步加剧岩体力学性能的恶化。

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引用次数: 0

Swelling creep diagenesis damage model for the Callovo-Oxfordian claystone Callovo-Oxfordian粘土岩的膨胀蠕变成岩损伤模型

IF 6.9 1区工程技术 Q1 ENGINEERING, GEOLOGICAL

Engineering Geology

Pub Date : 2024-09-20 DOI: 10.1016/j.enggeo.2024.107729

Jean-Claude Robinet , Asterios Valogiannis , Irini Djeran-Maigre

The French National Agency for Radioactive Waste Management (ANDRA) has been constructing an Underground Research Laboratory (URL) in Meuse/Haute-Marne since 2000 to determine the viability and protection of deep geological formation for hosting industrial nuclear waste repositories. The purpose of this URL is to describe the in situ properties and behavior of the Callovo-Oxfordian (COx) claystone. At the same time, various types of computational models have been developed to reproduce the in situ phenomena.

This paper presents an elastoviscoplastic model called SC2D: Swelling, Creep, Diagenesis, with anisotropic Damage, taking into account in situ measurements. This phenomenological model was developed to contribute to the understanding of the short- and long-term behavior of the COx claystone around the excavated drift. The model parameters are calibrated using in situ measurements and observations.

The model assumes that intact COx claystone (around from the excavated drift) exhibits elastic behavior with anisotropic damage in extension as macropores are occupied by calcite fibers. The short-term behavior of damaged COx claystone (near the excavated drift) is also characterized by an elastic mechanism with anisotropic damage. Sampling causes hydromechanical unloading that breaks the calcite fibers. Upon reloading the sample to site mean pressure, the damaged COx claystone first presents elastic behavior and then elastoplastic behavior depending on the load surface. Triaxial tests in axial compression and axial extension are conducted to validate this model with satisfactory results. Its long-term behavior follows an elastoviscoplastic mechanism.

法国国家放射性废物管理局（ANDRA）自 2000 年以来一直在默兹/上马恩省（Meuse/Haute-Marne）建造一个地下研究实验室（URL），以确定作为工业核废料储存库的深层地质构造的可行性和保护情况。该 URL 的目的是描述 Callovo-Oxfordian (COx) 粘土岩的原位特性和行为。与此同时，人们还开发了各种类型的计算模型来再现原位现象。本文结合原位测量结果，介绍了一种名为 SC2D：膨胀、蠕变、成因与各向异性损伤的弹塑性模型。这一现象学模型的开发有助于了解挖掘漂流物周围 COx 粘土岩的短期和长期行为。该模型假定完整的 COx 粘土岩（来自挖掘出的漂流物周围）表现出弹性行为，随着大孔隙被方解石纤维占据，在延伸过程中会出现各向异性损伤。受损的 COx 粘土岩（靠近挖掘出的漂流物）的短期行为也以各向异性损伤的弹性机制为特征。取样会导致水力机械卸载，使方解石纤维断裂。将样本重新加载到现场平均压力后，受损的 COx 粘土岩首先表现出弹性行为，然后根据加载面的不同表现出弹塑性行为。为验证这一模型，进行了轴向压缩和轴向延伸的三轴试验，结果令人满意。其长期行为遵循弹塑性机制。

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