scholarly journals Crack Evolution Characteristics and Cracking Mechanism of Red Beds in Central Sichuan during Seepage and Swelling

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Zhe Zhou ◽  
Shanxiong Chen ◽  
Yinhui Wang ◽  
Zhangjun Dai
Keyword(s):  
Water Absorption ◽  
Water Content ◽  
Rapid Development ◽  
Development Stage ◽  
Initial Water Content ◽  
Absorption Method ◽  
Initial Water ◽  
Evolution Characteristics ◽  
Cracking Mechanism ◽  
Final Crack

Crack is one of the important factors affecting the engineering characteristics of expansive rock and soil. In order to study the evolution characteristics and cracking mechanism of red beds in Central Sichuan during seepage and swelling, multiple groups of cracking tests are conducted under different initial states with a self-made device. In addition, combining swelling-softening mechanism of expansive rock and numerical analysis, the swelling-cracking mechanism is studied. The following research results are obtained. (1) The evolution process of swelling cracks is divided into three stages: the generation stage, the rapid development stage, and the stabilization stage. In the rapid development stage, the increase in the crack degree accounts for 90% of the whole process. (2) The final crack degree of the sample is related to the initial water content, water absorption method, and clay mineral content. The lower the initial water content, the greater the final crack degree of the sample. The final crack degree under the soaking water absorption method is greater than that under the capillary water absorption method, and the final crack degree of mudstone is greater than that of argillaceous sandstone and sandstone. (3) The development of swelling cracks is controlled by three significant values of water absorption, which are w 1 , w 2 , and w 3 , respectively, representing the beginning of cracking, the starting of the rapid development stage, and the starting of the stabilization stage. Among them, w 2 is of great significance in engineering practice. It shows that the development of cracks has entered a stage of rapid development, and the crack degree in this stage will increase exponentially with water absorption. (4) Uneven water absorption and uneven distribution of clay minerals lead to uneven swelling of expansive rock, which in turn generates swelling stress. Under the combined action of swelling stress and water swelling-softening, the internal structure of the rock is destroyed, leading to the generation and development of the cracks. Due to the different causes of uneven expansion, the mechanical mechanism of cracking and the shape of the resulting cracks will be different.

Analysis of the Damage Evolution Characteristics of Liaoxi Frost Sandy Soil on Dynamic Load

2013 ◽  
Vol 838-841 ◽  
pp. 805-810 ◽  
Author(s):  
Shu Guang Zhang ◽  
Pei Pei Chen ◽  
Jun Tong Sun
Keyword(s):  
Water Content ◽  
Sandy Soil ◽  
Dynamic Load ◽  
Dynamic Modulus ◽  
Damage Evolution ◽  
Confining Pressure ◽  
Initial Water Content ◽  
Sand Soil ◽  
Initial Water ◽  
Evolution Characteristics

To analyze the damage evolution characteristics of Liaoxi frost sand soil on dynamic load , firstly in the foundation of frozen soil damage theory,micro-strength and dynamic modulus are introduced to analyze the damage evolution characteristics of Liaoxi frost sandy soil .Then ,based on the dynamic triaxial test ,respectively analyze the influences made to dynamic modulus by confining pressure and initial water content . Some regular patterns are summarized .The greater the confining pressure, the greater the dynamic modulus of frost sand soil is ,and with the increase of dynamic strain the dynamic modulus under different confining pressure trend to be same .The bigger quantity of initial water content ,the greater the dynamic modulus is and the change rate of frost sand soil`s dynamic modulus with different initial water content are approximately equal .That initial water content has more significant effects on the dynamic modulus is found by the comparison of the effects caused by confining pressure and initial water content .

Influence of initial water content and strain rate on remolded yield stress in marine clay

2021 ◽  
pp. 1-8
Author(s):  
Xiaobing Li ◽  
Jianpeng Chen ◽  
Xiuqing Hu ◽  
Hongtao Fu ◽  
Jun Wang ◽  
...  
Keyword(s):  
Strain Rate ◽  
Water Content ◽  
Yield Stress ◽  
Initial Water Content ◽  
Marine Clay ◽  
Initial Water

scholarly journals Application of the Calorimetric Methods to the Characteristics of Seeds from Olives

Proceedings ◽  
2020 ◽  
Vol 70 (1) ◽  
pp. 90
Author(s):  
Andrzej Bryś ◽  
Joanna Bryś ◽  
Marko Obranović ◽  
Dubravka Škevin ◽  
Szymon Głowacki ◽  
...  
Keyword(s):  
Olive Oil ◽  
Water Content ◽  
Cooling System ◽  
Waste Product ◽  
Normal Pressure ◽  
Ash Content ◽  
Initial Water Content ◽  
Scanning Calorimetry ◽  
Initial Water

The olive oil industry represents an important productive sector in the Mediterranean basin countries. Olive stone is an essential by-product generated in the olive oil extraction industries and it represents roughly 10% by weight of the olive fruit. The seeds of pickled olives are also a significant waste product. In the present study, we have investigated the possibility of the use of differential scanning calorimetry for the thermal characterization of seeds from green and black pickled olives from Croatia. The differential scanning calorimeter (DSC) with a normal pressure cell equipped with a cooling system was used to determine the thermal properties of seeds from olives. The following analyses were also performed: the determination of calorific values in a pressure bomb calorimeter, the determination of initial water content, the determination of changes of water content during drying at the temperatures of 30 °C, 50 °C and 80 °C, the determination of a percentage content of seeds mass to the mass of the whole olives, and the determination of ash content. Seeds from olives are characterized by very good parameters as a biomass. The analyzed olive seeds were characterized by low water content, low ash content, and a relatively high caloric value.

scholarly journals Effects of Initial Water Content on Microstructure and Mechanical Properties of Lean Clay Soil Stabilized by Compound Calcium-Based Stabilizer

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1933 ◽  
Author(s):  
Chenglong Yin ◽  
Wei Zhang ◽  
Xunli Jiang ◽  
Zhiyi Huang
Keyword(s):  
Water Content ◽  
Soil Stabilization ◽  
Clay Soil ◽  
Soil Aggregates ◽  
Optical Microscope ◽  
Initial Water Content ◽  
Reaction Products ◽  
Unconfined Compression Test ◽  
Initial Water ◽  
X Ray

Initial water content significantly affects the efficiency of soil stabilization. In this study, the effects of initial water content on the compressibility, strength, microstructure, and composition of a lean clay soil stabilized by compound calcium-based stabilizer were investigated by static compaction test, unconfined compression test, optical microscope observations, environment scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. The results indicate that as the initial water content increases in the range studied, both the compaction energy and the maximum compaction force decrease linearly and there are less soil aggregates or agglomerations, and a smaller proportion of large pores in the compacted mixture structure. In addition, for specimens cured with or without external water supply and under different compaction degrees, the variation law of the unconfined compressive strength with initial water content is different and the highest strength value is obtained at various initial water contents. With the increase of initial water content, the percentage of the oxygen element tends to increase in the reaction products of the calcium-based stabilizer, whereas the primary mineral composition of the soil-stabilizer mixture did not change notably.

scholarly journals Solidification of High Organic Matter Content Sludge by Cement, Lime and Metakaolin

2018 ◽  
Author(s):  
Ke Rui ◽  
Wang Hongxing ◽  
Tan Yunzhi ◽  
Wang Lehua
Keyword(s):  
Organic Matter ◽  
Water Content ◽  
Organic Matter Content ◽  
Microscopic Analysis ◽  
Chemical Components ◽  
Orthogonal Experimental Design ◽  
Initial Water Content ◽  
Initial Water ◽  
Lime Content ◽  
Sheet Structure

Based on orthogonal experimental design, the key solidification controlling technology of Solidified/Stabilized (S/S) sludge with high total organic content (TOC) by cement, lime and metakaolin was explored by macroscopic tests, chemical components measurements and microscopic analysis. The macroscopic tests show that, the permeability coefficient is mainly affected by initial water content and lime content, and the unconfined compression strength is mainly affected by cement content and lime content. The chemical components measurements show that, the solidification effect of S/S sludge with high TOC is controlled by organic matter consumption, and organic matter consumption is determined by the alkaline environment from the cement and lime hydration reactions, which is mainly affect by the initial water content and lime-metakaolin content ratio. The microscopic analysis results show that, lime consumes parts of organic matter while excess lime produces weak Ca(OH)2 crystal fluffy sheet structure, matakaolin produces pozzolanic reactions with cement and lime instead of soil particles, and consumes the weak Ca(OH)2 crystal fluffy sheet structure produced by superfluous lime. The research has confirmed key controlling points of S/S sludge in case of high TOC, which will provide theoretical guidance and technical support for S/S sludge promotion with high TOC.

Determination of the tensile strength of unsaturated tailings using bending tests

2015 ◽  
Vol 52 (11) ◽  
pp. 1874-1885 ◽  
Author(s):  
Bibiana Narvaez ◽  
Michel Aubertin ◽  
Faustin Saleh-Mbemba
Keyword(s):  
Tensile Strength ◽  
Water Content ◽  
Water Retention ◽  
Water Retention Curve ◽  
Initial Water Content ◽  
Ambient Conditions ◽  
Initial Water ◽  
Bending Tests ◽  
Retention Curve ◽  
Apparent Cohesion

Bending tests were conducted on specimens of unsaturated tailings from three hard rock mines to evaluate their tensile strength. Saturated samples were prepared at an initial water content, w0, of 40% and then naturally dried under ambient conditions to pre-selected degrees of saturation, Sr, which can be related to the corresponding suction using the water retention curve. The basic interpretation of the bending tests results is based on an elastic–brittle behavior. The results show how the tensile strength, σt, of unsaturated tailings varies with water content, w (and Sr). The experimental data are also used to evaluate Young’s modulus in tension, Et, and to estimate the apparent cohesion, capp, as a function of Sr. Predictive equations are also applied to estimate the values of σt of unsaturated tailings using the water retention curve.

scholarly journals Temperature and seed moisture content affect electrical conductivity test in pea seeds

2017 ◽  
Vol 39 (4) ◽  
pp. 410-416 ◽  
Author(s):  
Lara Bernardes da Silva Ferreira ◽  
Nayara Alves Fernandes ◽  
Luan Costa de Aquino ◽  
Anderson Rodrigo da Silva ◽  
Warley Marcos Nascimento ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Moisture Content ◽  
Water Content ◽  
Initial Water Content ◽  
Seed Moisture Content ◽  
Initial Water ◽  
Test Efficiency ◽  
Seed Moisture ◽  
Pea Seeds ◽  
Initial Seed

Abstract: Several factors affect the electrical conductivity test efficiency, with emphasis given to the initial water content and the temperature during imbibition. This study aimed to evaluate the effect of the initial water content of pea seeds and the temperature on the electrical conductivity test efficiency. Six lots of ‘Mikado’ pea were used, which were previously tested for initial characterization. In the first trial, based on the initial value of the samples, the seed moisture content was adjusted to 9, 11, 13 and 15% and then the seeds were submitted to the electrical conductivity test. In the second trial, the water for seed imbibition was kept for 24 hours at 10, 15, 20, 25 and 30 ºC, and after that time the seeds were added and soaked for other 24 hours at the temperatures already mentioned. It was observed that initial seed moisture content and water temperature during imbibition influenced the results of the electrical conductivity test. This test should be carried out with distilled water, previously maintained for 24 hours at 25 °C for temperature stabilization. Then, the seeds with seed moisture content between 11 and 15% should be put to soak at 25 °C, and maintained at this temperature for 24 hours.

scholarly journals Study on the Mechanical Criterion of Ice Lens Formation Based on Pore Size Distribution

2020 ◽  
Vol 10 (24) ◽  
pp. 8981
Author(s):  
Yuhang Liu ◽  
Dongqing Li ◽  
Lei Chen ◽  
Feng Ming
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Water Content ◽  
Size Distribution ◽  
Initial Water Content ◽  
Mean Stress ◽  
Initial Water ◽  
Unfrozen Water Content ◽  
The Mean ◽  
Lens Formation

Ice lens is the key factor which determines the frost heave in engineering construction in cold regions. At present, several theories have been proposed to describe the formation of ice lens. However, most of these theories analyzed the ice lens formation from a macroscopic view and ignored the influence of microscopic pore sizes and structures. Meanwhile, these theories lacked the support of measured data. To solve this problem, the microscopic crystallization stress was converted into the macro mean stress through the principle of statistics with the consideration of pore size distribution. The mean stress was treated as the driving force of the formation of ice lens and induced into the criterion of ice lens formation. The influence of pore structure and unfrozen water content on the mean stress was analyzed. The results indicate that the microcosmic crystallization pressure can be converted into the macro mean stress through the principle of statistics. Larger mean stress means the ice lens will be formed easier in the soil. The mean stress is positively correlated with initial water content. At the same temperature, an increase to both the initial water content and the number of pores can result in a larger mean stress. Under the same initial water content, mean stress increases with decreasing temperature. The result provides a theoretical basis for studying ice lens formation from the crystallization theory.

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