Reinforced Soft Soil by CSV with/without Polypropylene fibres: Experimental and Numerical analysis.

Columns of mixed soil-sand-cement (CSV), is one of the most unknown used methods for soft soil stabilization that has not been studied before. To this end, in this paper, consolidated drained (CD) triaxial compression tests after have been cured for 28 days, were carried out to investigate the effectiveness of CSV, which is mainly used to reinforce soft soil. Then, the influence of soft soil content (25%, 50%, 75%) on materials of CSV with/without polypropylene (PP) fibers is established. The percentages of soft soils (50%, 75%) are experimentally doable and the remaining percentage (25%) was not successfully experimented; for this exact reason, an empirical formula is established based on the design of experiments (DOE) for calculating the soft soil’s characteristics. Then a numerical study using PLAXIS 3D is developed for studying the embankment building on soil which is reinforced by CSV. It is found that the efficacy of the reinforcement of the soft soil by CSV with/without PP fibers provides with satisfying results. Moreover, the less amount of soft soil on CSV materials the better for deviatoric stress, axial strain, the effective cohesion, the effective friction angle and modulus of elasticity E50. Additionally, when PP fibers is added to CSV material, experimental results were strongly affected. As far as the numerical study, the embankment building on the soil that is reinforced by the CSV shows an improvement in the level of displacement in the three directions, the total displacement and security factor. The variation of materials of CSV content with/without PP fibers, a diverse combination with a relatively lower effect can be easily remarked on the achieved results.

On Reflexivity in Ethnographic Practice and Knowledge Production

Deployed as much during fieldwork as in writing, reflexivity is itself positioned, its saliency as an epistemological device having transformed over time and space. Re-tracing its initial absence, subsequent rise in popularity and eventual routinization in academia, we position ourselves against reflexivity’s near-total displacement today by a narrow and increasingly prevalent understanding of positionality. We argue for a return to a broader and more relational understanding of reflexivity, proposing a methodological program to achieve and maintain its critical, ethical and political edge. Our aim is to engage in conversation about the value of reflexivity as an iterative and collaborative ethnographic endeavour with potential to produce more relational and engaged knowledge about increasingly overbearing field-sites in the Arab region and beyond.

Stabilization of Deep Roadways in Weak Rocks Using the System of Two-level Rock Bolts

Large rock mass deformation around deep roadways in the weak rocks was a significantproblem in mining activities in Vietnam and other countries. The excavation of roadways leads to highreleasing stress, which exceeds the peak strength of spalling surrounding rock and causes it to enter thepost-failure stage. Tensile failures then initiate and develop around the roadways, which causes thefragmentation, dilation, and separation of surrounding rock. The capacity of the primary support systemis low, which results in a severe contraction in the whole section of roadways, which requires findingsolutions to prevent the deformation of rock mass around roadways and technical solutions fromstabilizing for deep roadways. To stability analysis of roadways can be applied analytical, experimental,semi-experimental, and numerical methods. This paper introduces the prevention mechanism of largedeformation of rock mass around roadways using 2-level rock bolts. The research results show that usingthe system of two-level rock bolts can reduce the values of tensile stress on the boundary of roadwaysrange from 10 to 15% compared with only one. The importance of the total displacement of rock mass onthe boundary of roadways will be reduced from 3.47 to 13.85% using six long cable bolts.

Trueness of full-arch IO scans estimated based on 3D translational and rotational deviations of single teeth—an in vitro study

Objectives To three-dimensionally evaluate deviations of full-arch intraoral (IO) scans from reference desktop scans in terms of translations and rotations of individual teeth and different types of (mal)occlusion. Materials and methods Three resin model pairs reflecting different tooth (mal)positions were mounted in the phantom head of a dental simulation unit and scanned by three dentists and three non-graduate investigators using a confocal laser IO scanner (Trios 3®). The tooth-crown surfaces of the IO scans and reference scans were superimposed by means of best-fit alignment. A novel method comprising the measurement of individual tooth positions was used to determine the deviations of each tooth in the six degrees of freedom, i.e., in terms of 3D translation and rotation. Deviations between IO and reference scans, among tooth-(mal)position models, and between dentists and non-graduate investigators were analyzed using linear mixed-effects models. Results The overall translational deviations of individual teeth on the IO scans were 76, 32, and 58 µm in the lingual, mesial, and intrusive directions, respectively, resulting in a total displacement of 114 µm. Corresponding rotational deviations were 0.58° buccal tipping, 0.04° mesial tipping, and 0.14° distorotation leading to a combined rotation of 0.78°. These deviations were the smallest for the dental arches with anterior crowding, followed by those with spacing and those with good alignment (p < 0.05). Results were independent of the operator’s level of education. Conclusions Compared to reference desktop scans, individual teeth on full-arch IO scans showed high trueness with total translational and rotational deviations < 115 µm and < 0.80°, respectively. Clinical relevance Available confocal laser IO scanners appear sufficiently accurate for diagnostic and therapeutic orthodontic applications. Results indicate that full-arch IO scanning can be delegated to non-graduate dental staff members.

Higher-order Lamb waves with quasi-zero surface displacement components on a GaAs piezoelectric plate

Higher-order Lamb waves with quasi-zero surface displacement components are reported on (100)-cut GaAs propagating along the <110> direction where the total displacement at the surface of the plate is less than 10% of the maximum total displacement. The dispersion curves and the displacement component profiles show the reduction of total displacement at the surface of the plate starting when the phase velocities of the higher-order modes are crossing the shear bulk acoustic wave velocity to the value as low as 5%. Due to the concentration of acoustic energy inside the plate, the reported quasi-zero plate acoustic waves (QZ-PAW) further reduce the radiation of acoustic when the plate surface is in contact with liquid. The experimental results validate the occurrence of QZ-PAW with a reduction of viscous damping insertion loss compared to previously reported quasi-longitudinal Lamb waves (QL-LW). The results demonstrate the potential QZ-PAW mode for emerging applications such as dual-mode PAW sensors, PAW devices with integrated sensor and actuator, thin-film and ultra-high frequency (UHF) PAW sensors in highly viscous liquid media.

Anti-pulling Force and Displacement Deformation Analysis of the Anchor Pulling System of the New Debris Flow Grille Dam

To avoid waste from a large section space structure layout and deep burial to improve the structural strength and stability, anchor technology is introduced, and combined with the advantages of the supporting wall, a new debris flow grille dam is proposed. Starting from the force process and damage mechanism of the new debris flow grille dam, the computation formula for the anti-pulling force and the total displacement is given. The anti-pulling force includes the sidewall frictional resistance of the anchor pier and the positive pressure of the front end face of the anchor pier. The total displacement includes three parts: the elastic deformation of the cable, the relative shear displacement between the anchor pier and the surrounding soil, and the compression deformation of the soil at the front of the anchor pier. Finally, the influence of soil parameters and anchor pier size on the anti-pulling force and displacement deformation of the anchor-pulling system is analyzed by examples, and the results are compared with the numerical results. The results show that the displacement deformation decreases gradually with increasing elastic modulus of the soil around the anchor pier and increases with increasing Poisson's ratio. The change in elastic modulus mainly affects the relative shear displacement of the anchor pier and soil and the compressive deformation of the soil at the front end of the anchor pier. Poisson's ratio has the greatest influence on the relative shear displacement of the anchor pier and soil. A larger anchor pier is not better; thus, it is wise to choose the economic design dimension. Theoretical and numerical simulation results are consistent, showing a linear growth trend. The results of this paper can further improve the theoretical calculation method of the new debris flow grille dam, thus making it widely used in more debris flow control projects.

Biomechanical Comparison of a Prepared Thick Fresh Frozen Irradiated Fascia Lata Allograft to the Native Superior Capsule (212)

Objectives: Superior Capsule Reconstruction (SCR) has been described as treatment option for irreparable tears of the superior rotator cuff. Reported outcomes on the success of the surgery have been variable, with graft choice seeming to be one of the most important factors. Fascia Lata (FL) allograft has been proposed as a potential option as it provides adequate graft thickness while avoiding the morbidity of an autograft harvest. The purpose of this study was to compare the biomechanical characteristics of an SCR with FL allograft (FL-SCR) to a native superior capsule in a cadaveric specimen. Methods: Eight cadaver shoulder specimens were used. Each specimen was tested with a custom shoulder system twice. Initial testing was performed after the specimen was dissected of all soft tissue except for the native superior capsule. Subsequent testing was performed after FL-SCR was done. All allografts were fresh frozen and irradiated. Capsule and graft dimensions were recorded before testing. Biomechanical values recorded were cyclic and load to failure for both the native capsule and FL-SCR, and fixation displacement for the SCR-FL construct. A Paired T-test was performed to compare the biomechanical values of the native superior capsule to the FL-SCR. Results: The mean thickness of the NSC was 2.4 ± 0.6 mm and 7.4 ± 1.2mm for the FL graft. The native superior capsule had an average linear stiffness of 94.5 ± 20.4 N/mm, yield load of 386.9 ± 63.6 N, ultimate load of 444.9 ± 67.7 N and energy absorbed of 1418.4 ± 248.8 N-mm. The FL-SCR construct had an average linear stiffness of 28.0 ± 1.6 N/mm, yield load of 123.8 ± 54.3 N, ultimate load of 369.0 ± 43.4 N and energy absorbed of 5021.2 ± 755.1 N-mm. Comparing the two groups there was a statistically significant difference for stiffness (P = 0.013), yield load (P = 0.03) and energy absorbed (P = 0.003). There was no statistically significant difference between ultimate load. The total displacement of the FL-SCR fixation was 5.8 ± 0.6 mm after 1 cycle, 8.5 ± 0.7 mm after 30 cycles, 11.4 ± 1.8 mm at the yield load and 29.5 ± 1.8 mm at the ultimate load. For the failure mode, 8/8 NSC specimens failed at the mid-substance. The FL-SCR, 3/8 specimens failed at the suture tendon interface and 4/8 had medial anchor pull out. Conclusions: Performing SCR with FL allograft in a cadaver model creates a construct that is sufficiently strong enough to withstand normal physiologic loading of the shoulder, although it does not fully re-create the biomechanical characteristics of a native shoulder superior capsule.

Assessing the Vertical Displacement of the Grand Ethiopian Renaissance Dam during its Filling using DInSAR technology and its Potential Acute Consequences on the Downstream Countries

The Grand Ethiopian Renaissance Dam (GERD), formerly known as the Millennium Dam, is currently under construction and has been filling at a fast rate without sufficient known analysis on possible impacts on the body of the structure. The filling of GERD not only has an impact on the Blue Nile Basin hydrology, water storages and flow but also pose massive risks in case of collapse. Rosaries Dam located in Sudan at only 116 km downstream of GERD, along with the 20 million Sudanese benefiting from that dam, would be seriously threatened in case of the collapse of GERD. In this study, through the analysis of Sentinal-1 satellite imagery we show concerning deformation patterns associated with different sections of the GERD&rsquo;s Main Dam (structure RCC Dam type) and the Saddle Dam (Embankment Dam type). We processed 109 descending mode scenes from Sentinel-1 SAR imagery, from December 2016 to July 2021, using the Differential Synthetic Aperture Radar Interferometry technique to demonstrate the deformation trends of both - the GERD&rsquo;s Main and Saddle Dams. The time-series generated from the analysis clearly indicates different displacement trends at various sections of the GERD as well as the Saddle Dam. Results of the multi temporal data analysis on and around the project area show inconsistent subsidence at the extremities of the GERD Main Dam, especially the west side of the dam where we recorded varying displacements in the range of 10 mm to 90 mm at the crest of the dam. We conducted the current analysis after masking the images with a coherence value of 0.9 and hence, the subsequent results are extremely reliable and accurate. Further decomposition of the subsiding rate has revealed higher vertical displacement over the west side of the GERD&rsquo;s Main Dam as compared to the east side. The local geological structures consisting of weak zones under the GERD&rsquo;s accompanying Saddle Dam adds further instability to its structure. We identified seven critical nodes on the Saddle Dam that match the tectonic faults lying underneath it, and which display a varying degree of vertical displacements. In fact, the nodes located next to each other displayed varying displacement trends: one or more nodes displayed subsidence since 2017 while the other node in the same section displayed uplift. The geological weak zones underneath and the weight of the Saddle Dam itself may somewhat explain this inconsistency and the non-uniform vertical displacements. For the most affected cells, we observed a total displacement value of ~90 mm during the whole study period (~20 mm/year) for the Main Dam while the value of the total displacement for the Saddle dam is ~380 mm during the same period (~85 mm/year). Analysis through CoastSat tool also suggested a non-uniformity in trends of surface water-edge at the two extremities of the Main Dam.

Study and evaluation of the stability of underground mining method used in shallow-dip vein deposits hosted in poor quality rock

Purpose.This article proposes to analyze and determine the mining design for shallow-dip deposits hosted in poor quality rock. Methods. We used the UBC tool to find the optimal exploitation method, the Rock mass rating (RMR) and Q-system (Q) to determine the optimal mining stope and the recommended rock support, the numerical modeling by RS2 software with a variety of geotechnical, geometrical, and technical conditions to analyze the evolution of the unstable zone width and the maximum total displacement around the stope after excavation. Findings. The optimum mining method designated by the UBC tool for this type of deposit is the cut and fill. By projecting the obtained RMR and Q-system values on the design graph, it is concluded that the operating stope is located in the stable zone with a height of 3 m, and bolting support is recommended. The simulation by RS2 software reveals that the optimal mining design that can be used to mine shallow-dip vein deposits hosted in poor quality rocks consists of a 3 m high stope and a 75° dip with cemented backfill. Originality.This work presents a study to choose the most suitable underground mining method and mine design for shallow-dip deposits hosted in poor quality rock. Practical implications.In the mining industry, the success of operating an underground mine is conditioned by the selection of the appropriate method, of the mining design and dimensioning of a rock support adapted to the nature of the rock, and excavation geometry according to the type and nature of the deposit.

Surrounding Rock Stability Control Technology of Roadway in Large Inclination Seam with Weak Structural Plane in Roof

The surrounding rock control technology of mining roadways in large inclination seams with a weak structural plane in the roof is one of the most challenging fields in underground roadway support. In view of the serious deformation of the surrounding rock of the transportation roadway in the 1201 working face of a mine, the deformation and failure characteristics and instability mechanism of the surrounding rock of the roadway are analysed. The self-stability mechanical model of the roof block structure of the roadway with a large inclination under the support effect is established, and the support concept of “high pre-stressed asymmetric” and the combined support method of bolts, wire mesh, and cables are proposed. The rationality of the supporting scheme is verified by numerical simulation. The results show that: compared with bolt and wire mesh support, the maximum shear displacement of the roof’s weak layer under the combined support of bolt, wire meshes, and cable before and after mining is reduced by 86.78% and 83%, respectively, and the maximum total displacement of surrounding rock surface is reduced by 49.22% and 37.1%, respectively. The field monitoring results show that the combined support scheme can effectively control the deformation of the surrounding rock.