Side Slope Research Articles

Study on Model and Experimental of Laser Scribing Parameter of Maskant in Chemical Milling for Aerospace Applications

In order to solve the problems of multiple process parameters, difficult control and high process requirements in laser first/second scribing of aerospace chemical milling thin-wall parts, a laser scribing depth model based on thermal energy balance was established, and the relationship between laser power and speed was established with scribing depth as a target. Using AC850 laser scribing maskant as coating material, the effects of laser power, scribing speed, laser frequency, forward angle and side slope angle on the scribing depth were studied by single factor experiment. Experimental results show that the theoretical model is in good agreement with experimental data. The laser scribing depth is positively proportional to the laser power and inversely proportional to the laser speed and has little relationship with the laser frequency. The predicted accuracy of the mathematical equations regarding the laser power density and scribing depth, calculated by the laser power, speed and scribing depths experimental data, are 88.53% and 90.79%. The laser scribing depth at a forward angle of 6° and a side slope angle of 7° is deeper compared with the vertical incident scribing depth, and the angle is also the recommended angle of laser scribing. Based on the simplified regression model, the laser scribing depth model can be directly used in the laser NC system to realize the adaptive adjustment and accurate control of laser energy according to the actual laser speed.

Processes and Features of Subsidence Dolines (Sinkholes)

This study deals with the processes of subsidence dolines. These processes contribute to the understanding of the characteristics of karst areas and the relation between dolines and their environment. For this, several hundred dolines of various karst areas were studied. Investigations included measurements of doline size and processes (for example mass movements), the mapping of their morphology and processes, observation and tracking of some processes (for instance water inflow). Laboratory experiments were carried out, and we had VES measurements performed to obtain data on their sediments. The processes of dolines with various development phase were distinguished. The processes of developed dolines were classified according the site of their effect which may be present in the environment, on the side slope, on the floor, on the cover below the floor and in the bedrock. The processes were also put into groups based on their direction. It was established that the degree of supplier and transporting away processes and their value compared to each other controls doline size, while the denudation of the doline slope and the accumulation on its floor influences doline shape.

Force and deformation response analysis of dual structure slope excavation and support

Aiming at the problem of fuzzy selection basis of dual-structure slope simulation calculation parameters and the complicated force and deformation of the slope body in the supporting process. The study relies on the treatment project of the right side slope of the K5 + 220-K5 + 770 section of the TJ1A section of the Jiangwen Expressway. The slope is a gravel soil-weathered bedrock dual structure slope, which is referred to as Hetangba slope in the study. Use Midas/GTS NX to build a trial calculation model. A new method for checking simulation parameters of deep displacement monitoring data is proposed. The superposition calculation method of pore water pressure is proposed to realize the slope stress-seepage coupling. The analysis method of slope excavation and support process is put forward. The analysis shows that the most dangerous working condition in the slope excavation and support process is the second-level excavation. When there is a local displacement and plastic strain concentration area on the slope, the reference significance of the extreme value and the safety factor is reduced. Compared with the application of pore water pressure and no pore water pressure, there is no obvious change in the position of the extreme value of horizontal displacement and plastic strain in working conditions 2–8, but the extreme value changes are different. The slope safety factor of working conditions 2–8 is reduced. The continuous distribution zone of plastic strain inside the slope disappeared in condition 7. There is a very small unstable area on the top of the third-level slope of working conditions 9–11. The research results have great theoretical guiding significance for the measurement and control simulation and early warning analysis of the dual structure slope construction process.

Understanding the Seepage Behavior of Nai Gaj Dam through Numerical Analysis

This study presents the seepage patterns of earth-fill dams, using critical situations by employing the finite element approach. The Nai Gaj dam is 65km northwest of Dadu city in Sindh Province, Pakistan. In this study, the seepage through the main dam body and foundation is computed and simulated for different scenarios, i.e. maximum, normal, and minimum reservoir level. Seepage analysis was conducted by using the SEEP/W sub-program of GEO-SLOPE software. Dam design parameters and dam geometry data were used as input data to compute the unknown seepage. The seepage behavior of the Nai Gaj dam is shown in terms of net flow which consists of equipotential lines, streamlines, velocity vectors, and phreatic lines. The results show the seepage flux, maximum seepage, and exit gradient at different reservoir levels. The results show that the average flow rate at normal, maximum, and minimum reservoir levels are 1.49×10-7cumec/m, 3.38×10-7cumec/m, and 2.108×10-8cumec/m respectively. In addition, the overall stability of the side slope of the dam is discussed.

Decomposition of water vapor flux divergence and its application to a blizzard event over Ili Valley in Central Asia during 30 Nov to 1 Dec 2018

Central Asia is experiencing an increase in the occurrence of extreme flood events while still featuring in scarce precipitation. These extreme events are governed by weather systems of various scales as well as complex terrain effects. It is therefore difficult to analyze and forecast precipitation with traditional methods. In this study, an approach is designed by decomposing water vapor flux divergence (Qvall) under model's terrain following coordinates following the Helmholtz theorem. The traditionally used but important variable for depicting anomalous precipitation, Qvall, is partitioned into three components, i.e., flow divergence (Qvdiv), moisture advections by large-scale motion (QvL) and by sub-synoptic motion (QvS). Applications to a blizzard event occurred over Ili Valley during 30 Nov to 1 Dec 2018 is performed as an example. The eastward water vapor flux brings moisture from Balkhash Lake to Ili Valley during the entire precipitation event, while Qvall fails to indicate the initiation and weakening of precipitation. Temporal and spatial evolutions of the three decomposed components are analyzed with comparison to precipitation on both windward slope and lee side. Qvdiv with dominant magnitude always converges no matter precipitation intensifies or weakens, and therefore leads to false moisture aggregation signals in Qvall. The other two components, QvL and QvS, converge prior to precipitation and diverge or weaken before the event ends. Besides, QvL performs better than QvS on windward slope and shows moisture transport from upper levels while QvS achieves better on lee side. Future applications of this flow decomposition approach may thus extend to improving precipitation predictions with negligible computational costs over complex topography in other places around the world.

A GA-BP Neural Network Regression Model for Predicting Soil Moisture in Slope Ecological Protection

In this study, based on a highway project in Zhejiang, China, the meteorological factors and soil moisture of high side slopes were monitored in real time by a meteorological data monitoring system, and the correlation between soil moisture and meteorological factors was investigated using the obtained data of soil moisture and total solar radiation, atmospheric temperature, soil temperature, relative humidity, and wind speed. Based on the correlation and the influence of meteorological factors on soil moisture lag, a back propagation (BP) neural network regression model optimized with genetic algorithm (GA) was proposed for the first time and applied to soil moisture prediction of high side slopes. The results showed that the BP neural network regression model and the GA-BP neural network regression model were used for soil moisture prediction in two cases without and with lags, respectively, and both prediction methods showed a more significant improvement in prediction accuracy considering their lags compared with those without lags; the GA-BP neural network regression model outperformed the BP neural network regression model in terms of accuracy. V-fold cross-validation eliminated the effect of random errors, indicating that the model can be applied to soil moisture prediction for ecological conservation. Using the soil moisture prediction results as the basis for screening ecological slope protection vegetation is of great significance to the safety and reliability of road construction.

Chaotic mixing in a free‐helix extruder using a new solution to the biharmonic equation

AbstractA recently published approach for modeling the cross flow in an extruder channel using a new solution to the biharmonic equation is utilized in a study of chaotic mixing in a free‐helix single‐screw extruder. This novel extruder was designed and constructed with the screw flight, also referred to as the helix, detached from the screw core. The flight‐helix had straight sides that more closely emulated rectangular channel theory than the nominal sloped sides of a conventional single screw channel. Each of the screw elements could be rotated independently to obtain chaotic motion in the screw channel. Using the new extruder, experimental evidence for the increased mixing of a dye, for both a Dirac and droplet input, with a chaotic flow field relative to the traditional residence time distribution is presented. These experimental results are compared using the new biharmonic equation‐based model. Comparing the experimental chaotic mixing with theoretical calculations was facilitated by a recently published technique for accurately placing the dye in the extruder channel. Because of the ability to periodically rotate only the flight/helix, the chaotic mixing results are minimally confounded by the existence of Moffatt eddies.

CASE STUDY ON PERFORMANCE MONITORING AND STABILITY ANALYSIS OF BAISHIHU SUSPENSION BRIDGE AND SIDE SLOPE

The main structure of the Baishihu suspension bridge was connected to the anchor foundations by three main steel cables. The wooden pedestrian deck was fixed to the main steel cables using steel beams and was stabilized by two stabilizing cables. The stabilizing cables and bridge body were joined by 44 steel connecting rods. Therefore, the slope stability at the anchorage foundations of the main steel cables, as well as the performance monitoring and analysis of the main steel cables and stabilizing cables, are critical to the overall performance of the suspension bridge. This paper discusses the performance monitoring and analysis of the steel cable deflection and cable strength for this bridge, as well as the main considerations and results of the stability analysis of the bridge abutments and side slopes of the two banks. Water-level observation wells, inclinometers, and tiltmeters monitoring were used to record reference data for the analysis of the slope stability performance. Additionally, the three-dimensional dynamic analysis program VFIFE was used to analyze the deformation and motion of the bridge. The final steady-state results were used to compare the static design value and monitoring data. The dynamic response before the final steady state was also observed.

Stabilitas Tanah Timbunan Sisi BH-1 Proyek Jalan Akses Pembangunan Jembatan Pulau Balang II

Problem on the road access landfill at Balang Island II Bridge is the landslide at STA 23+025 on left side slope (BH-1) caused by a swamp pond on the roadside. The landfill that cutted into the swampy area made the water get stuck on one side (water could not flow to the original condition). The research method is the form of direct observation in the field which focuses on the results of information and laboratory testing which is then processed and analyzed. The analysis obtained that the soil type on the spot is clay with N-SPT 6 – 29. There are 2 alternatives solutions for the problem. First, if there is a ROW problem, the treatments are watercourse, adding counterweight, wooden pile under the landfill and one layer Geotextile PP 50 (initial ground water level on exsisting condition with 90,4 kPa loads). Second, if there is no ROW problem, the treatments are watercourse, adding counterweight, wooden pile under the landfill and one layer Geotextile PET 100 (initial ground water level on top of landfill with 90,4 kPa loads). Based on technical analysis, the second solution was chosen because it has bigger safety factor, smallest settlement value, and shorter time implementation. However it is still need more detail technical justification to strengthen the desicion.

Enriching Roadside Safety Assessments Using LiDAR Technology: Disaggregate Collision-Level Data Fusion and Analysis

Fatalities and serious injuries still represent a significant portion of run-off-the-road (ROR) collisions on highways in North America. In order to address this issue and design safer and more forgiving roadside areas, more empirical evidence is required to understand the association between roadside elements and safety. The inability to gather that evidence has been attributed in many cases to limitations in data collection and data fusion capabilities. To help overcome such issues, this paper proposes using LiDAR datasets to extract the information required to analyze factors contributing to the severity of ROR collisions on a localized collision level. Specifically, the paper proposes a new method for extracting pole-like objects and tree canopies. Information about other roadside assets, including signposts, alignment attributes, and side slopes is also extracted from the LiDAR scans in a fully automated manner. The extracted information is then attached to individual collisions to perform a localized assessment. Logistic regression is then used to explore links between the extracted features and the severity of fixed-object collisions. The analysis is conducted on 80 km of roads from 10 different highways in Alberta, Canada. The results show that roadside attributes vary significantly for the different collisions along the 80 km analyzed, indicating the importance of utilizing LiDAR to extract such features on a disaggregate collision level. The regression results show that the steepness of side slopes and the offset of roadside objects had the most significant impacts on the severity of fixed-object collisions.

Analysis of the Stability of Reinforced Plastic Waste Treated Clay as Embankment Fill on Soft Soils

The purpose of this study is to analyze the suitability and stability of clay soil treated with plastic waste as an embankment fill. Plastic wastes are used to stabilize the locally found weak clay. The locally found weak clay soil is stabilized with plastic waste. The stability analyses of the proposed slope have been done by finite element method using geotechnical software PLAXIS 2D. The stability analyses were performed for different conditions considering the geometry of the embankment, characterization of fill material, and the strength of reinforcement. Different models were analyzed to determine the safe height, side slope, and tensile strength of geogrid required to stabilize the embankment in addition to that of unreinforced embankments. The factor of safety of each trial is taken to check the stability of the modeled embankments. Accordingly, the factor of safety increases as geogrid axial stiffness increases greater than 500 kN/m. The analysis results revealed that with increasing slope height and slope angle the factor of safety decreases. This study found that plastic waste treated clay could be used as embankment fill when reinforced with geogrid.

Design, Fabrication, and Experimental Investigation of Screw Auger Type Feed Mechanism for a Robotic Wheat Drill

Highlights An auger-type feed mechanism was designed for a robotic wheat drill, and a laboratory investigation was carried out. To avoid seed blockage, the recommended screw auger pitch must be at least 150% of the maximum seed dimension. The performance of the feed mechanism was influenced by auger speed, vibration, and slope. This study delivered a bulk feed mechanism for wheat drilling, which can be easily scaled and adopted by small autonomous vehicles or mobile robots. Abstract. Cultivating the arable, highly sloped hills and uneven terrain is challenging and unsafe with large agricultural machines. Therefore, a fleet of small autonomous ground vehicles (AGVs) was proposed to farm sloped or uneven terrain. The fleets need a robotic grain drill to operate on varying slopes, and the success of the fleet depends on the performance of the robotic seeder or grain drill. The feed mechanism is the heart of the seeder, and its design and performance influence the plant population and crop yield. In this study, we designed and fabricated an auger-type feed mechanism for robotic wheat drilling. Feed mechanisms with augers having three different pitches were developed as per the ASABE standards. The developed feed mechanism was investigated in a laboratory setup for flow rate and flow uniformity in accordance with ISO standards. The predictor variables were auger type (pitch), auger rotational speed, vibration, and slope. The auger flow rate for flat slopes was a linear function of auger speed and varied from 30 g/min to 170 g/min. The coefficient of variation (CV) for the flow rate ranged from 2% to 10%. The CV was within acceptable limits, which was an excellent indicator of the bulk feed mechanism's flow uniformity. The performance of the feed mechanism was influenced by vibration and slope. However, the auger flow rate remained constant for vibration frequencies of 0, 6, and 14 Hz, suggesting that the feed mechanism was vibration-proof and could tolerate the vibration frequency up to 14 Hz. The flat, downhill (descending), and uphill (ascending) slope levels did not affect the feed mechanism performance. However, the side slopes (right and left slope) significantly affected the feed mechanism flow rate but did not affect the flow uniformity. The study also developed a feed mechanism for a sloped-ground prototype seeder, which can be easily scaled and adopted by small autonomous vehicles or mobile robots. Keywords: Flow rate, Flow uniformity, Multi-robot, Robotic seed drill, Screw auger, Seed rate.

Numerical Simulation of the Stability of a Cutting Slope and Study on Its Reinforcement Scheme

Analyzing the stability of the slope and studying the reinforcement scheme can reduce ecological disasters, improve the ecological environment, and protect people’s lives and property. In this paper, taking the left side slope of ZK100 + 860∼+975 cutting of the Huizhou‐Qingyuan section of the Shantou‐Zhanjiang Expressway as an example, based on the strength reduction method (SRM), the stability of the slope under different conditions (natural conditions, unsupported excavation conditions, rainstorm conditions, and reinforcement conditions) is analyzed by using finite element software. The results show that the slope was almost stable before excavation, and the safety factor of slope stability decreases due to excavation, so it is in an unstable state. Rainwater has a great influence on the stability of the slope. The damage to the slope is deepened, and the stability safety factor is decreased under the rainstorm condition. The stability safety factor of the slope has increased by 24.3% after the reinforcement of the anchor rod and anchor cable, and the slope is in a stable state. It can be seen that the anchor rod and anchor cable can effectively control the deformation of the slope and have a good reinforcement effect.

Strategies of GIS‐Based Urban Country Park Planning and Ecological Restoration

Purpose. This study centers around the Wangzhanghe Country Park located in Jiaozuo City as the research object. Through analysis of the site’s evolution by GPS and its status‐quo by GIS, the map of spatial distribution suitability has been illustrated. Design. Based on the major principle of achieving sustainable development of the ecosystem and the derived concept of building a diversified landscape, we have developed the overall scheme of planning and landscape layout of the country park. Specifically, the area of ecological restoration is further divided into the areas of quarry restoration, bare land restoration, slope protection, vegetation, and dam maintenance, and restorative measures are put forward accordingly. Findings. Our research findings indicate that thanks to the vegetation restoration of the side slope, the area of bare land in mountain farmland has been evidently reduced, whereas the severely damaged ash pits and green spots have also been restored. Originality: in the meantime, we have leveraged the flat space at the foot of the mountain to foster a viewing experience and provide recreational activities for citizens, so that they are able to effectively increase their access to outdoor events and improve their sense of engagement and experience in the events, thereby providing a reference for building a green, diverse, and sustainable system of ecological services for the urban country park.

Evaluation and Analysis of the Effect of Lignin Amelioration on Loess Collapsibility

The road subgrade and road surface in collapsible loess area are prone to many engineering diseases such as uneven subgrade settlement, insufficient bearing capacity of soaked foundation, collapse and instability of subgrade side slope due to the special properties of loess. As an environment-friendly, low-cost soil modifier with good adhesion and chelation properties, lignin has been considered to be used in highway subgrade construction. In order to explore the effect of lignin on loess, the compressive and collapsible properties of modified loess with different lignin contents were analyzed based on consolidation compression test. The improvement mechanism of lignin on loess collapsibility was studied by means of infiltration test and SEM test. The results show that lignin fibers can promote the agglomeration of loose particles and form a network structure in the soil particle pores, enhance the cementation strength between particles and soil skeleton, and reduce the permeability of loess. With the increase of lignin fiber content, the improvement degree of loess collapsibility shows a trend of first increasing and then decreasing. When the lignin fiber content is 2%, the effect is the best, and the improved loess collapsibility is eliminated.

Quantitative Analysis of Concrete Lining Damage in Field Canals by Frost Heave Using a Water–Heat–Mechanical Coupling Model

Concrete linings of field canals are seriously damaged by frost heave in the north of China. However, the mechanism causing lining damage is too complex to be described quantitatively, and present models are insufficient in considering soil–lining interaction. Based on mechanical analysis and the direct shear test, the restrictive relationship between the freezing soil and lining is introduced as a key point to quantitatively simulate the process of lining damage. Heat convection, solar radiation, and a moving water table boundary are also incorporated in the present model to simulate boundary conditions with daily climate data. Finally, two cases in the Hetao irrigation district are simulated. The developed model agrees with experiment data and can reflect the failure characteristics of lining. The results show: (1) the contact interface between lining and freezing soil will slide early in the freezing season, (2) reducing the freezing strength or weakening the restrictive relationship between the lining and freezing soil can reduce the maximum stress of the lining, (3) new lining structures with shapes like parabola and catenary perform better than a round-bottom-triangular (RT) shape because of a gentler side slope, and (4) large amounts of migration water accumulate and freeze beneath north (shady) slopes and cause a high damage risk for the lining. This paper can provide a reference for the further study of efficient and economical engineering methods for solving the lining damage problem.

Study on the Influence of the Slope Composition of the V-shaped Tunnel on the Smoke Exhaust Efficiency of the Point Exhaust System

The influences of the slope composition on both sides of the variable slope point and the opening numbers of the exhaust vent on the smoke diffusion and the smoke and heat exhaust efficiency in V-shaped tunnel were investigated by the numerical method. The results showed that for the asymmetric V-shaped tunnel, increasing the number of exhaust vents on the large slope side can improve the smoke and heat exhaust efficiency, but control the smoke in a smaller rang is relatively difficult. The corresponding smoke exhaust vent opening strategy should be drawn up in accordance with the composition of the slope of the V-shaped tunnel and the goal of the smoke control system in practice.

Experiments on Stability of Tetrapods on Rear Slope of Rubble Mound Structures under Wave Overtopping Condition

In this study, hydraulic model tests were performed to investigate the stability of armor units at harbor side slope for rubble mound structures. The Korean design standard for harbor and fishery port suggested the design figures that showed the ratio of the armor weight for each location of rubble mound structures and it could be known that the same weight ratio was needed to the sea side and harbor side (within 0.5H from the minimum design water level) slope of rubble mound structures. The super structures were commonly applied to the design process of rubble mound structures in Korea and the investigation of the effects of super structures would be needed. The stability number (Nod = 0.5) was applied (van der Meer, 1999) and it showed that the armor (tetrapod) weight ratio for harbor side slope of rubble mound structures needed 0.8 times of that for sea side slope.

The Influence of Shell Permeability on Stability of Upstream Slope during Rapid Drawdown – Khassa Chai Earth Dam as a Case Study

Several factors affect the stability of earth dam during sudden drawdowns such as permeability and mechanical properties of soil, upstream side slope, drawdown ratio, and drawdown rate. This paper investigates the influence of shell permeability on earth dam upstream slope stability and its role in the change of pore water pressure at different locations of the embankment during the sudden drawdown, using different limit equilibrium methods. To accomplish the objective of this study, (Geo Studio 2012 Software) as one of the powerful geotechnical programs was used for the modeling and numerical analysis. The study shows that decreasing in the shell permeability resulted in the reduction of pore water pressure dissipation and variation of shell hydraulic conductivity plays a vital role in the overall stability of the upstream slope under rapid drawdown conditions.

Seasonal variability of stratified flow properties in a Non-tidal Strait-A field study

The Bosporus Strait, connecting the Black Sea and the Marmara Sea in Turkey, is an example of a hydrodynamically complex strait. The Strait features a multi-layered (typically two-layer) flow system and is an example of (nearly) non-tidal exchange flow. A comprehensive measurement program including long- and short-term flow velocity, water level (near both entrances of the waterway), salinity, temperature, meteorological parameters (wind speed, wind direction, and atmospheric pressures at both entrances), and discharges of the Danube River were analyzed for the period between October 2004 and October 2005. The results show high variability in the layer velocities and salinities both temporally and spatially, and the typical two-layered current structure could be sustained for water level differences (the Black Sea minus the Marmara Sea) between zero and +45 cm. However, unidirectional flow, either northward or southward, is found at times, mostly in the fall and winter due to the severe meteorological (especially wind) conditions. The river inflow to the Black Sea is a strong control on the water level in the Bosphorus Strait—and, therefore, on the current structure—during the springtime and there is around a one-month phase lag between the peak river discharges and the peak water level increase in the strait. The relationship between the water level difference of the strait and the flow properties (thicknesses and flow rates) of both layers was also quantified from the cross-sectional current measurements. The velocity structures show both high qualitative and quantitative variability between the main channel and the side slopes of the cross-sections, and taking profile measurements on the slope without cross-sectional data may give a misleading assessment of the flow structure at the point of interest. There is strong mixing between the two layers throughout the strait causing a variation of 4–5 in the salinity of both layers between the two entrances. The non-dimensional flow rate calculation showed that the maximum exchange through the strait occurred for Composite Froude numbers (G2) of around unity.