Study of a strength prediction model of unsaturated compacted expansive soil under freeze–thaw cycles

2022 ◽  
Vol 15 (2) ◽  
Author(s):  
Zhongnian Yang ◽  
Qi Zhang ◽  
Wei Shi ◽  
Zhaochi Lu ◽  
Zhibin Tu ◽  
...  
2021 ◽  
Vol 687 (1) ◽  
pp. 012007
Author(s):  
Li Tingke ◽  
Peng Yuanchun ◽  
Li Jiadi ◽  
Dulin ◽  
Lian Xingqin

2003 ◽  
Vol 15 (1) ◽  
pp. 87-94
Author(s):  
Moo-Han Kim ◽  
Jong-Ho Jang ◽  
Jae-Hyun Nam ◽  
Bae-Su Khil ◽  
Suk-Pyo Kang

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Haiyong Cheng ◽  
Shunchuan Wu ◽  
Xiaoqiang Zhang ◽  
Junhong Li

Paste backfilling is an important support for the development of green mines and deep mining. It can effectively reduce a series of risks of underground goaf and surface tailings ponds. Reasonable strength of backfill is an effective guarantee for controlling ground stress and realizing safe mining function. Under the combination of complex materials and local conditions, ensuring the optimal design and effective proportion for paste backfill strength is the bottleneck problem that restricts the safety, economy, and efficiency of filling mining. The strength developing trend of paste backfilling prepared from waste rock and unclassified tailings has been studied. Different levels of cement contents, tailings-waste ratios, and slurry concentrations were investigated through orthogonal design to obtain the relationship between the UCS and the multi-influential factors. Combined with the experimental results and the previous strength prediction models, the waste rock-unclassified tailings paste strength prediction model was proposed. Introducing the water-cement ratio, the cement-tailings ratio, the amount of cement, and the packing density that characterizing the overall gradation of unclassified tailings and waste rock, as well as the curing time, a strength prediction model of multifactors was developed. Moreover, the microscopic structure of the paste prepared from waste-unclassified tailings was analyzed with an Environment Scanning Electron Microscope (ESEM), and the influence mechanism was ascertained. The weight coefficient of strength development is carded in this paper, and the strength model of unclassified tailings-waste paste considering five factors is obtained, which is of great significance to guide the mining engineering.


1977 ◽  
Vol 21 (2) ◽  
pp. 132-136
Author(s):  
Robert S. Lower ◽  
Rodney K. Schutz ◽  
Thomas L. Sadosky

A study was conducted to determine if a mathematically compact model could be derived to predict arm strength for seated subjects. The purpose of the study was to determine the appropriate algebraic form of the model, and the precise numerical value of the parameters in the model was of secondary interest. An extensive data base of arm strength measurements was compiled for one subject. A detailed analysis of push strength at 65 positions in the shoulder height, transverse plane was performed and a strength prediction model was derived. The forearm was always rotated to the mid-position in this first set of data. A second, more general, set of data was collected at 972 test positions by evaluating 54 (x, y, z) hand locations, three forearm rotations (promotion, mid-position and supination) and six directions of force (left, right, up, down, push and pull). This second set of data was continually referred to in deriving the push strength model. Based on this comparative analysis, it is hypothesized that the algebraic form of the push strength model is appropriate in evaluating more general types of test conditions.


2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Yanlong Li ◽  
Zili Wang ◽  
Yang Luo

Shear strength of shallow expansive soil varies along with the depth under the freeze-thaw effect. This work investigates shear strength characteristics of shallow expansive soil by simulating the actual freeze boundary conditions of seasonal frozen areas with water supplement. An integrated approach incorporating the freeze-thaw test and direct shear test was adopted. Firstly, unidirectional freezing tests for expansive soil columns under three different freezing temperature gradients were carried out. Secondly, direct shear tests under low vertical stress were performed on the standard samples, which were prepared by using cutting rings cut the thawed expansive soil columns into nine segments along with the depth. Temperature, water content, and dry density at different depths were also investigated after the freeze-thaw process. The test results showed that, after the freeze-thaw process, the shear strength of expansive soil columns showed significant differences along with the depth and highly correlated with water content, specifically the higher water content and the lower shear strength. The minimum shear strength in the expansive soil columns occurred at the soil layer below the frozen and unfrozen zones interface. The expansive soil column’s shear strength changed most under the moderate freezing temperature gradient corresponding to the most considerable shear strength reduction. Moreover, the significant decrease in cohesion was the main reason for the shear strength reduction of expansive soil after the freeze-thaw process. These results indicate significant depth variability in shear strength of expansive soil under the freeze-thaw effect.


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