A meso-damage-based constitutive model for yellow sandstone under dry–wet cycles
Zhe Qin, Runchang Zhang, Weizheng Mao, Jihuan Han, Zhiwen Li, Sunhao Zhang
发布时间：2024-02-26
关键词：constitutive model, damage coupling, dry–wet cycles, particleflow code, rock mechanics
摘要：in this study, meso-damage of a yellow sandstone is investigated and a meso-damage-based constitutive model for dry–wet cycles is proposed. First, computed tomography scanning and uniaxial compression tests were conducted on yellow sandstones under different dry–wet cycles. Second, the evolution of rock mesostructures and the damage mechanism subjected to dry–wet cycles were simulated using the discrete element method with Particle Flow Code in 2 Dimensions (PFC2D) software. Third, a constitutive model was proposed based on the meso-statistical theory and damage mechanics. Finally, this constitutive model was verified with the experimental results to check its prediction capability. It is found that the radius and number of pore throats in the sandstone increase gradually with the number of dry–wet cycles, and the pore structure connectivity is also improved.
阅读全文 PDF 引用Numerical study on local scour characteristics around submarine pipelines in the Yellow River Delta silty sandy soil under waves and currents
Peng Yu, Ruigeng Hu, Jike Zhang, Qi Yang, Jieru Zhao, Lei Cao, Chenghao Zhu
发布时间：2024-02-20
关键词：local scour, numerical simulation, submarine pipelines, Yellow River Delta
摘要： The results indicate that (1) local scour around submarine pipelines can be divided into three stages: rapid scour, slow scour, and stable scour. The maximum scour depth occurs directly below the pipeline, and the shape of the scour pits is asymmetric. (2) As the water depth decreases and the pipeline suspension height increases, the scour becomes more intense. (3) When currents go through a pipeline, a clear stagnation point is formed in front of the pipeline, and the flow velocity is positively correlated with the depth of scour. This study can provide a valuable reference for the protection of submarine pipelines in this area.
阅读全文 PDF 引用Effects of elevated ground temperatures on properties of cement grouts for deep rock grouting
Zhipeng Xu, Jianping Sun, Runguo Li, Lei He, Changwu Liu
发布时间：2024-02-05
关键词：Effects of elevated ground temperatures on properties cement grouts for deep rock grouting
摘要： This paper aims to experimentally gain insights into the effects of elevated ground temperatures on the properties of cement grout in fresh and hardened states in deep rock grouting. The results revealed that a temperature of 35°C is crucial for changes in the properties of thick cement grout with a water–cement ratio of less than 0.8. When the temperature is up to 35°C, there can be significant improvements in rheological parameters, acceleration of grout setting, and increase in the rheological time dependence of thick cement grout; however, there may also be a slight impact on the initial grout flowability and the nature of shear thinning.
阅读全文 PDF 引用Offshore high-grade limemud resources of west coast of India: Economic potential and industrial applications
Anil Kumar Adukadukkam, Rachna Pillai, Mamatha Puthiyathara Kanakamma
发布时间：2024-01-10
关键词：beneficiation, industrial grade, offshore limemud, west coast of India
摘要： Chemical, physical, mineralogical, beneficiation, and agglomeration studies found the offshore limemud as a potential replacement for limestone in the cement, filler, blast furnace, steel melting shop, lime production, paint, and Grade-I steel industries. An assessment of mining and transportation costs indicates that the offshore limemud (USD 5–6/ton) is more cost-effective than that imported from other countries (USD16-18/ton). With several advantageous factors like low impurity, mode of occurrence in overburden-free stratified form, fine-grained slurry nature, and shallow water depth, sustainable mining of offshore limemud could be a future reality with controllable technological, economic, and environmental challenges.
阅读全文 PDF 引用Impact of well placement and flow rate on production efficiency and stress field in the fractured geothermal reservoirs
Xinghui Wu, Meifeng Cai, Xu Wu, Ketong Zhang, Ziqing Yin, Yu Zhu
发布时间：2023-12-28
关键词：geothermal exploitation performance, geothermal reservoir, massflow rate, stressfield, well placement
摘要： The results indicate that the longer distance between wells can increase the outlet temperature of production wells and improve extraction efficiency in the short term. In contrast, the shorter distance between wells can reduce the heat exchange area and thus mitigate the impact on the reservoir stress. A larger mass flow rate is conducive to the production capacity enhancement of the geothermal system and, in turn causes a wider range of stress disturbance. These findings provide valuable insights into the optimization of geothermal energy extraction while considering reservoir safety and long-term sustainability. This study deepens the understanding of the THM coupling effects in geothermal systems and provides an efficient and environmentally friendly strategy for a geothermal energy system.
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