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Unsaturated shear strength of coal mine spoil
Published in N. Khalili, A.R. Russell, A. Khoshghalb, Unsaturated Soils: Research & Applications, 2020
S. Fityus, H. Robertson, L. Bradfield, J. Simmons
Overall, the results imply a strong non-linearity in the unsaturated shear strength envelope, for both φ and φb. In evaluating the reasonableness of this, two aspects of this work must be borne in mind. First, the minespoil is a complex soil material, comprising soil particles and mixed rock fragments. It has a strongly bimodal pore size distribution (mudrock fragment pores are much smaller than pores in the spoil) and the rock fragments are relatively strongly cemented, but with a significant wet-dry strength variation. Hence, changes in the bulk degree of saturation have many complicated consequences for the saturation and suction of both populations of pores, as well as for the integrity of coarser particles.
Sediments and Sedimentary Rocks
Published in Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough, Earth Materials, 2019
Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough
Geologists name siliciclastic sedimentary rocks based primarily on grain size (Table 8.3). Confusion can arise, though, because some names used for siliciclastic rocks are the same words used in the Udden-Wentworth scale (Table 8.1) to classify sediments by mean grain diameters. But rocks, in contrast with well-sorted sediments, may contain grains that include a range of sizes. Additionally, the term clay refers to clasts of the finest grain sizes and also to a specific kind of mineral. Yet, clay-sized clasts are not always composed of clay minerals. And finally, the names mudrock and mudstone sound similar but do not mean the same things. Mudrock is a general term for very fine-grained rocks that may be either mudstone or shale.
Phytoplankton as main organism in the Eocene organic-rich turbidites of Jiyang Depression, China: Implication for organic matter accumulation mechanism
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Jianguo Zhang, Zaixing Jiang, Siqi Wang, Xiangxin Kong
The organic matter in turbiditic mudrock is dominated by Dinoflagellates, indicating Dinoflagellates blossom. The single type of algae blossom should be the results of algae blooms because only algae blooms can result in high and dominant content of algae in the water column. It is hard to directly seek the trace of algae blooms from turbiditic mudrock because those traces were destroyed by turbidity current. On the other hand, the interbedded laminated shale of turbiditic mudrock provides the clues (Figure 7a). The interbeded laminated shale is characterized by “three-tiered rhythm”, which is composed of horizontally calcite lamina, organic matter lamina, and clay lamina in ascending order (Figure 7b). The depositional process of the three-tiered rhythm is explained as follows. Firstly, the algae blooms change the water geochemistry and promote the deposition of micrite lamina in late Spring to Summer. Secondly, these algae die and rapidly deposit to lake bottom soon afterward, forming as organic matter lamina. Finally, only some clays are able to deposit when the water column is not suitable for algae survival in late autumn to winter. Therefore, “three-tiered rhythm” indicates Dinoflagellates blooms. Warm-humid climate condition is suitable for Dinoflagellates blooms in the Jiyang Depression, explained as follows. The heavy rainfall and large river run-off in warm-humid condition transport abundant nutrient (e.g., N, P, K) to lake, providing the material source for algae blooms.
A comprehensive stability evaluation method of multiple salt caverns underground gas storage with interlayers
Published in Petroleum Science and Technology, 2022
Jinghong Peng, Jun Zhou, Guangchuan Liang, Cao Peng, Shijie Fang
The initial geostress field of the model needs to be solved before numerical simulation. The salt cavern UGS studied in this paper is a deeply buried project, and the initial geostress field is the superposition of the tectonic stress field and the self-weight stress field. The lateral pressure coefficient of salt rock is set as 1, and that of mudrock is set as 0.85. Combined with the established boundary conditions, the fast stress boundary method (S-B method) is used to solve the initial geostress field. Figure 5 shows the maximum unbalance force and displacement of a node in the numerical model in the process of solving static equilibrium. As can be seen from Figure 5, with the increase of calculation time, the maximum unbalance force of the node gradually decreases and approaches zero, and the change of node displacement gradually slows down and finally approaches a constant value. This shows that the model has reached static equilibrium and can be used in the next numerical simulation.