Digital Evaluation of Micro-Pore Water Effects on Mechanical and Damage Characteristics of Sandstone Subjected to Uniaxial, Cyclic Loading–Unloading Compression by 3D Reconstruction Technique

2021 ◽  
Author(s):  
Xiao-Ping Zhou ◽  
Da-Chao Jiang ◽  
Zhi Zhao
Keyword(s):  
Cyclic Loading ◽  
3D Reconstruction ◽  
Pore Water ◽  
Reconstruction Technique ◽  
Damage Characteristics ◽  
Digital Evaluation ◽  
Water Effects

TIME TO THE END OF PRIMARY CONSOLIDATION (EOP) OF SOFT CLAYEY SOILS: CONCERNING THE EFFECT OF ATTERBERG’S LIMIT AND CYCLIC LOADING HISTORY

2019 ◽  
Vol 128 (2B) ◽  
pp. 29-41
Author(s):  
Trần Thanh Nhàn
Keyword(s):  
Cyclic Loading ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Clayey Soils ◽  
Loading History ◽  
Cyclic Shear ◽  
Wide Range ◽  
Primary Consolidation ◽  
Time Required

In order to observe the end of primary consolidation (EOP) of cohesive soils with and without subjecting to cyclic loading, reconstituted specimens of clayey soils at various Atterberg’s limits were used for oedometer test at different loading increments and undrained cyclic shear test followed by drainage with various cyclic shear directions and a wide range of shear strain amplitudes. The pore water pressure and settlement of the soils were measured with time and the time to EOP was then determined by different methods. It is shown from observed results that the time to EOP determined by 3-t method agrees well with the time required for full dissipation of the pore water pressure and being considerably larger than those determined by Log Time method. These observations were then further evaluated in connection with effects of the Atterberg’s limit and the cyclic loading history.

scholarly journals 3D Reconstruction with Single-Shot Structured Light RGB Line Pattern

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4819
Author(s):  
Yikang Li ◽  
Zhenzhou Wang
Keyword(s):  
3D Reconstruction ◽  
Moving Objects ◽  
Structured Light ◽  
Color Space ◽  
Reconstruction Technique ◽  
Single Shot ◽  
Line Pattern ◽  
Hsv Color Space ◽  
Phase Map ◽  
Line Segmentation

Single-shot 3D reconstruction technique is very important for measuring moving and deforming objects. After many decades of study, a great number of interesting single-shot techniques have been proposed, yet the problem remains open. In this paper, a new approach is proposed to reconstruct deforming and moving objects with the structured light RGB line pattern. The structured light RGB line pattern is coded using parallel red, green, and blue lines with equal intervals to facilitate line segmentation and line indexing. A slope difference distribution (SDD)-based image segmentation method is proposed to segment the lines robustly in the HSV color space. A method of exclusion is proposed to index the red lines, the green lines, and the blue lines respectively and robustly. The indexed lines in different colors are fused to obtain a phase map for 3D depth calculation. The quantitative accuracies of measuring a calibration grid and a ball achieved by the proposed approach are 0.46 and 0.24 mm, respectively, which are significantly lower than those achieved by the compared state-of-the-art single-shot techniques.

scholarly journals Mechanical response and pore pressure generation in granular filters subjected to uniaxial cyclic loading

2018 ◽  
Vol 55 (12) ◽  
pp. 1756-1768
Author(s):  
Jahanzaib Israr ◽  
Buddhima Indraratna
Keyword(s):  
Cyclic Loading ◽  
Pore Pressure ◽  
Pore Water ◽  
Mechanical Response ◽  
Pore Water Pressure ◽  
Axial Strain ◽  
Water Pressure ◽  
Internal Erosion ◽  
Excess Pore Water Pressure ◽  
Excess Pore

This paper presents results from a series of piping tests carried out on a selected range of granular filters under static and cyclic loading conditions. The mechanical response of filters subjected to cyclic loading could be characterized in three distinct phases; namely, (I) pre-shakedown, (II) post-shakedown, and (III) post-critical (i.e., the occurrence of internal erosion). All the permanent geomechanical changes such, as erosion, permeability variations, and axial strain developments, took place during phases I and III, while the specimen response remained purely elastic during phase II. The post-critical occurrence of erosion incurred significant settlement that may not be tolerable for high-speed railway substructures. The analysis revealed that a cyclic load would induce excess pore-water pressure, which, in corroboration with steady seepage forces and agitation due to dynamic loading, could then cause internal erosion of fines from the specimens. The resulting excess pore pressure is a direct function of the axial strain due to cyclic densification, as well as the loading frequency and reduction in permeability. A model based on strain energy is proposed to quantify the excess pore-water pressure, and subsequently validated using current and existing test results from published studies.

scholarly journals Linear Correction and Matching Method for 3D Line Structure Reconstruction

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Di Jia ◽  
Yuxiu Li ◽  
Si Wu ◽  
Ying Liu
Keyword(s):  
3D Reconstruction ◽  
Large Scale ◽  
Computational Cost ◽  
Small Neighborhood ◽  
Line Detection ◽  
Reconstruction Technique ◽  
Matching Method ◽  
Line Structure ◽  
Straight Line ◽  
Linear Correction

The 3D reconstruction technique using the straight-line segments as features has high precision and low computational cost. The method is especially suitable for large-scale urban datasets. However, the line matching step in the existing method has a mismatching problem. The two main reasons for this problem are the line detection result is not located at the true edge of the image and there is no consistency check of the matching pair. In order to solve this problem, a linear correction and matching method for 3D reconstruction of target line structure is proposed in this paper. Firstly, the edge features of the image are extracted to obtain a binarized edge map. Then, the extended gradient map is calculated using the edge map and the gradient to establish the gradient gravitational map. Secondly, the straight-line detection method is used to extract all the linear features used for the 3D reconstruction image, and the linear position is corrected by the gradient gravitational map. Finally, the point feature matching result is used to calculate the polar line, and the line matching results of the adjacent three images are used to determine the final partial check feature area. Then, random sampling is used to obtain the feature similarity check line matching result in the small neighborhood. The aforementioned steps can eliminate the mismatched lines. The experimental results demonstrate that the 3D model obtained using the proposed method has higher integrity and accuracy than the existing methods.

The role of pore water plays in coal under uniaxial cyclic loading

2019 ◽  
Vol 257 ◽  
pp. 105125 ◽  
Author(s):  
Chunlin Zhong ◽  
Zhenyu Zhang ◽  
Pathegama Gamage Ranjith ◽  
Yiyu Lu ◽  
Xavier Choi
Keyword(s):  
Cyclic Loading ◽  
Pore Water

scholarly journals Minimally invasive reconstruction technique for chronic Achilles tendon tears allows rapid return to walking and leads to good functional recovery

2019 ◽  
Vol 28 (1) ◽  
pp. 305-311 ◽  
Author(s):  
Paweł Bąkowski ◽  
Kinga Ciemniewska-Gorzela ◽  
Krzysztof Talaśka ◽  
Jan Górecki ◽  
Dominik Wojtkowiak ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Minimally Invasive ◽  
Achilles Tendon ◽  
Invasive Technique ◽  
Reconstruction Technique ◽  
Injured Limb ◽  
Tendon Reconstruction ◽  
Isokinetic Test ◽  
Tendon Tears ◽  
Achilles Tendon Reconstruction

Abstract Purpose Chronic Achilles tendon tears, including chronic ruptures with end gap over 6 cm making end-to-end suturing impossible, can be treated with autologous hamstring graft reconstruction. The primary goal of this study was to present the biomechanical and long-term clinical results of recently developed minimally invasive Achilles tendon reconstruction technique. Methods Minimally invasive Achilles tendon reconstruction was applied to 8 foot and ankle cadaveric specimens as well as 18 patients with chronic Achilles tendon tears. Repaired cadavers were subjected to the biomechanical testing using a cyclic loading protocol. Patients with reconstructed Achilles tendon were subjected to the clinical, functional and isokinetic tests at 12 months after the treatment. Results All of tested Achilles cadaveric specimens survived 2 loading blocks (250 cycles of 10–100 N load followed by additional 250 cycles of 10–200 N load). With three specimens, it was possible to perform the third cyclic loading block with 20-300 N load and two specimens survived the fourth block with 20–400 N load. Therefore, a mean number of 838 cycles (±178) within the range of 509–1000 was recorded. Two specimens which survived all 1000 cycles were pulled to failure at 25 mm/s rate. The results obtained in the load to failure testing were as follows: 398 N and 608 N of maximum load. The results of functional heel rise endurance test and single leg hop for distance test indicated a decrease in the endurance and strength of the injured limb. However, the results of the weight-bearing lunge tests indicated no tendency for elongation of the Achilles tendon. A comparative analysis of the isokinetic test results for the non-injured and injured limb was revealed no statistically significant differences for every isokinetic test (n. s.), with significant difference for isometric strength parameters (p = 0.0006). Conclusions The results of the biomechanical tests as well as 1-year extensive functional, clinical and isokinetic results of the minimally invasive technique for chronic Achilles tendon tears are encouraging. Patients returned to their normal physical activity, including sport pre-injury level in most cases. Level of evidence III

Influence of cycling pore-water pressures and principal stress ratios on drained deformations in clay

1992 ◽  
Vol 29 (2) ◽  
pp. 326-333 ◽  
Author(s):  
K. D. Eigenbrod ◽  
J. Graham ◽  
J.-P. Burak
Keyword(s):  
Cyclic Loading ◽  
Pore Water ◽  
Seasonal Changes ◽  
Triaxial Tests ◽  
Strain Rates ◽  
Natural Clay ◽  
Groundwater Levels ◽  
Deviator Stress ◽  
Pore Water Pressures ◽  
Stress Ratios

Seasonal changes in groundwater levels affect the rate of downhill creep movements in slopes. This process has been studied in triaxial tests on undisturbed specimens of a natural clay from Bluefish Lake, 50 km north of Yellowknife, N.W.T. Specimens were first anisotropically consolidated to low stresses that correspond to conditions at shallow depths in creeping slopes. Pore-water pressures (back pressures) in the specimens were then cycled systematically (over periods lasting 4–48 h) with the drainage leads open. Resulting axial and volumetric strains were measured, and shear and lateral strains deduced from them. Strain rates decreased with increasing total times of testing. They increased with increasing values of the ratio Δu/Δuf, with increasing values of deviator stress q, and with decreasing values of [Formula: see text]. Systematically increasing the pore-water pressures in the specimens produced clear estimates of failure at low stresses. Key words : slope, clay, creep, cyclic loading, ground water, triaxial.

Triangulation Based on 3D Reconstruction Technique

2011 ◽  
Vol 121-126 ◽  
pp. 4249-4253 ◽  
Author(s):  
Zhen Jie Hou ◽  
Li Guo Gu
Keyword(s):  
3D Reconstruction ◽  
Surface Area ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Reconstruction Technique ◽  
Object Model ◽  
Incremental Method ◽  
Mesh Model ◽  
Triangular Mesh Model ◽  
Three Dimensional Space

For decades of research on triangulation, Scattered surface area triangulation has achieved some results, but a lot of algorithms extended to three-dimensional space still have some problems.In this paper I analyzes the existing algorithms and propose a idea based on the Combination of the incremental method and divide algorithm ,which directly realize the triangulation of scattered points in space. Through the triangulation of space scattered point ,it's result eventually meet the triangular mesh model of the reconstruction and the mesh is very uniform. The model reproduce the object model intuitively and clearly. This study provide meaning of the reference and guide in such a work

Sign in / Sign up

Export Citation Format

Share Document