Microstructures of different soil layers caused by the high-rise building group in Shanghai

Cui, Zhen-Dong; Tang, Yiqun

doi:10.1007/s12665-010-0673-5

Cited by 29 publications

(6 citation statements)

References 27 publications

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“…where, P was the applied pressure; d was the pore diameter of the sample, σ was the surface tension (N/m) and θ was the contact angle between the pore wall and the mercury. The contact angle was assumed 140 • in this study [37,38].…”

Section: The Mip Experimentsmentioning

confidence: 99%

Study on the Preparation and Hydration Properties of a New Cementitious Material for Tailings Discharge

et al. 2019

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Blast furnace slag (BFS) is often used as a cement-based raw material for underground filling and surface cemented paste discharge of tailings during mining processes. This paper studied a new cement-based material (NCM) with BFS to replace ordinary Portland cement (OPC). A uniaxial compressive strength (UCS) experiment was used to test the mechanical strength of samples; X-ray diffraction and thermal gravity experiments were used to test the crystalline phases and amount of hydration products by samples; a scanning electron microscope experiment was used to observe the influence of the hydration products morphology by samples; mercury intrusion porosimetry experiment was used to analyze the pore size distribution of samples. The samples with NCM had an optimum UCS; the crystalline phases of the hydration products were similar in OPC and NCM. However, the amount of product formed in OPC was less than that in NCM at the same curing time; more ettringite and calcium silicate hydrate were produced in samples with NCM, which filled the pores and enhanced the UCS of the samples. The final mercury intrusion volume of the samples with NCM were lower than the samples with OPC at the same curing time, which showed that samples with NCM had lower porosities. For the samples with NCM and OPC cured from 7 days to 28 days, the mercury intrusion volume was reduced by 18% and 13%, and the most common pore size of the samples reduced by 53% and 29%, respectively. This showed after 21 days curing time, the pores of all the samples getting smaller; however, the samples with NCM were more compact. The main ingredients of the NCM were clinker, lime, gypsum and BFS, and its ratio was 14:6:10:70. The content of additives to NCM was 0.4%, and the ratio of sodium sulfate: alum: sodium fluorosilicate was 2:1:1.Processes 2019, 7, 47 2 of 17 combined both methods and proposed the technology of cemented paste discharge of tailings (CPDT) [10,11]. The method involved adding some cement to the tailings and discharging them to valleys or subsidence areas; the tailings need to be transported by pipes or belts. This method guarantees the stability of the tailings for the cemented piles. In addition, mines no longer need to build tailings pond and can also achieve safe pile-up. Because the cemented tailings pile can be built up to a high height, the limited footprint can pile up more tailings than tailings ponds. Presently, this technology has been applied and developed in some metal mines [11].During the cemented paste backfill, the amount of cement was 2% to 7% of the total weight of the tailing slurry, and it may be up to 10% to remain independent across pillar extraction process [12]. Cement costs account for more than 60-80% of the filling costs, as discussed by Li et al. [13]. The idea of CPDT was derived from cemented paste backfill, thus, the process of CPDT was similar to this, and the cost of cement also occupied a large proportion of CPDT costs. Therefore, the search for cheap, cementitious industrial by-products to replace cement and ...

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Section: The Mip Experimentsmentioning

confidence: 99%

Study on the Preparation and Hydration Properties of a New Cementitious Material for Tailings Discharge

et al. 2019

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“…Among them, MIP has been widely used due to its large measurement range and good repeatability of measurement results (Romero and Simms, 2009;Lubelli et al, 2013;Lopes, 2016;Wang et al, 2016). Cui and Tang (2011) used MIP to study the evolution of the pore size distribution of natural structures in soft soil during compression, and proposed the concept of the pore structure damage potential, which is used to characterize the variation in the pore distribution with load. Tang and Yan (2015) revealed the micromechanism of the effect of freeze-thaw cycles on soil strength through mercury intrusion tests and scanning electron microscopy.…”

Section: Introductionmentioning

confidence: 99%

Micropore Structure and Fractal Characteristics of Clays Due to Freeze-Thaw and Compression Based on Mercury Intrusion Porosimetry

et al. 2022

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The artificial ground freezing method has been widely used in shield end reinforcement and connecting channel reinforcement of urban subway tunnel in water-rich soft soil. Accurate quantification of micropore change and redistribution due to freeze-thaw is important to understand frost heave and thaw settlement of soft soils including mucky clay and silty clay. This paper presents Mercury Intrusion Porosimetry (MIP) data for mucky clay and silty clay specimens before and after freeze-thaw and compression. MIP tests were conducted on the soil samples of undisturbed soil, frozen-thawed soil, compressed soil and compressed frozen-thawed soil. The pores of clays were divided into five groups according to the diameter, including 1) macro pore, 2) medium pore, 3) small pore, 4) micro pore, 5) ultramicro pore. Micro pores and ultramicro pores account for more than 80% of clays’ total pore volume and pore surface area. The pore distribution characteristics of mucky clay and silty clay were studied, and the pore volume and pore surface area distributions’ capacity dimension was estimated. The particle contact, pore changes of clays due to freeze-thaw and compression were analyzed quantitatively. Total pore volume and pore surface area of clays increased due to freeze-thaw, and decreased due to compression correspondingly. The distribution of clays’ pore volume and pore surface area have statistical self similarity, and it is effective to quantify the microstructure changes of clays due to freeze-thaw and compression by estimating capacity dimension, which can provide a new way to reveal the internal micro-pore change of clays due to freeze-thaw and compression quantitatively.

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“…The interaction of the structural characteristics of the soil constituents is the main object of the study. The complexity of soil properties stems from the differences, changes, and interactions of the physical structure of the various components within the soil [4,5]. Analyzing the basic nature of soil from its structural characteristics is a reliable way of knowing the mechanical performance of the material.…”

Section: Introductionmentioning

confidence: 99%

Quantitative Analysis of 3D Reconstruction Parameters of Multi-Materialsin Soft Clay

Liu

Song

Yang

et al. 2018

JMSE

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The results of the three-dimensional reconstruction of soil were derived from the X-ray absorption coefficient of the material itself. However, the absorption coefficient is not a fixed value, and is related to densities, chemical molecular weight, and the weight percentages of chemical components. How to accurately obtain the density of one component is a vital issue in multi-materials. In this study, the influence of the physical parameters of each component in the data-constrained modeling (DCM) of the microstructure of soft clay was investigated. The results showed that density changes were more prominent. A reasonable multi-component density was calculated, and the density of organic matter had a significant effect on the volume percentage of three-dimensional soft clay. In the clay mineral montmorillonite, the density significantly affected the volume percentage data, which directly limited the accuracy of the material distribution analysis. Based on this, other physical parameters of each component in the data constraint model could be further explored. Based on the density value of the simple material, a reasonable multi-materials density was calculated, which provides a quantitative method for the evolution analysis of soil structure.

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Microstructures of different soil layers caused by the high-rise building group in Shanghai

Cited by 29 publications

References 27 publications

Study on the Preparation and Hydration Properties of a New Cementitious Material for Tailings Discharge

Study on the Preparation and Hydration Properties of a New Cementitious Material for Tailings Discharge

Micropore Structure and Fractal Characteristics of Clays Due to Freeze-Thaw and Compression Based on Mercury Intrusion Porosimetry

Quantitative Analysis of 3D Reconstruction Parameters of Multi-Materialsin Soft Clay

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