A study on settlements of road embankments on soft ground using vertical drains
Trang: 1477-1488 Trinh Dinh ToanTóm tắtIn civil engineering, the study of embankment settlement on soft ground is a vital geotechnical task in order to maintain serviceability of the road embankment, pavement, and facilities. This paper presents a study on settlements of road embankment on soft ground using vertical drains, including prefabricated-vertical drain (PVD), sand drain (SD), and sand compaction pile (SCP) on a number of packages of Hanoi – Haiphong Expressway Construction Project. The effectiveness of settlement prediction of vertical drain solutions is evaluated considering the ratios between the observed consolidation settlements and settlements predicted in the Detailed Design, in relation to the thickness of soft soil and the depth of treatment. Regression analysis is used to establish the correlation between the observed settlement and the height of embankment. The results show that (i) the design generally overestimated settlements; (ii) the ratios between observed and predicted settlements tend to positively correlate with the thickness of soft soil and the depth of treatment, and (iii) there are positive correlations between the height of embankment and the observed settlement. These correlations can be a valuable source of reference for anticipating settlements in basic design of highway projects with soft ground treated by vertical drains, in the regions that have geological stratum similar to Thabinh and Haihung formations of Bacbo Plain
Seismic analysis of a soil-liquid tank system using the two-step method
Trang: 1489-1501 Huynh Van QuanTóm tắtSeismic analysis of soil-structure interaction (SSI) is a challenge due to the non-linearities of soil-foundation interaction (SFI). The reliability of the design and the analysis results will suffer if SSI is ignored. In this paper, a two-step method based on the superposition theorem is used to perform a seismic analysis of a soil-foundation-tank-liquid system (soil-liquid tank system). The SFI analysis was conducted in the first step using the CyclicTP program's finite-element method. Meanwhile, the liquid tank system was analyzed in the second step using the lumped-parameter method. Numerical simulations conducted in homogeneous strata of sand soil demonstrated that the responses of the liquid tank were 24–70% higher than the results of the fixed-base model. Compared to the sway-rocking model, these responses did not differ by 20%. This study also investigated cohesive soils of homogeneous clays and multiple strata. The paper recommends that future research investigate the experimentation, the geometric nonlinearity of the soil-foundation system, and the stress-strain analysis of the tank wall
Trang: 1502-1517 Huynh Phuong Nam, Tran Le Anh Duc, Phan Hoang Nam, Nguyen Minh Hai, Phan Da ThaoTóm tắtFiber-reinforced polymer (FRP) bars have garnered increasing attention in recent years due to their superior corrosion resistance, offering a potential solution to the significant drawback of steel corrosion in concrete. For the widespread utilization of FRP bars in concrete structures, determining the bond strength between FRP bars and concrete is a crucial topic. This study seeks to develop a prediction model to estimate the bond strength of FRP bars in concrete, utilizing an extended dataset from 1010 pull-out tests. Initially, the study evaluates the applicability of several bond strength formulas from existing codes. Subsequently, two prediction models, namely a multivariate linear regression model and an artificial neural network (ANN) model, are introduced for estimating the bond strength of FRP bars in concrete. The results indicate that the correlation between the evaluation values of existing formulas and the experimental value is very low. This is because these formulas have not yet been updated to encompass the expanded usage scopes of FRP bars with various surface processing methods and types of concrete. While the multivariate linear regression model outperforms these formulas, its accuracy is still relatively low; in contrast, the ANN demonstrates superior performance, achieving an R^2 value for both the validation and test set of more than 0.92. The findings highlight that, when considering a broader range of applications, the ANN serves as a robust tool for accurately predicting the bond strength of FRP bars in concrete, in comparison to traditional formulas and linear regression models. This assessment approach provides engineers with a convenient, high-precision tool for designs utilizing various forms of FRP bars and diverse types of concrete in practical design scenarios
Trang: 1518-1528 Hoang Viet Hai, Nguyen Hoang QuanTóm tắtRehabilitation the flexural capacity of reinforced concrete structures has been the subject of many studies. However, there is currently limited research on repairing such structures using Ultra-High-Performance Concrete (UHPC) and the combination of UHPC with Fiber-Reinforced Polymer (FRP) materials. This article presents the results of an experimental study on the flexural behavior of 4 specimens: 1 specimen of reinforced concrete (RC), 1 specimen strengthened with FRP sheets, and 02 specimens with the same height as the RC specimen but with a replacement of 3 cm of the protective concrete layer with a UHPC layer, either bonded or not bonded to the existing concrete, with or without the reinforcement of FRP sheets. The experimental results of the 4-point bending tests indicate that, while maintaining the height of the RC specimen constant, replacing the protective concrete layer with a UHPC layer and incorporating FRP in the tension zone led to an increase of approximately 83.35% in flexural capacity, with the deflection at the failure stage rising by only 12.8%. This research opens up a new and promising direction for improving and extending the service life of RC bridges using UHPC and FRP
Nonlinear interfacial contact laws in multi-layer elastic-viscoelastic structural systems
Trang: 1529-1543 Tran Nam Hung, Nguyen Thi Thu NgaTóm tắtLayered structures are widely used in construction, such as pavement structures consisting of multiple layers of different materials or interfaces between bricks and mortar in masonry structures, etc. In analyzing such structures, understanding the properties of the interface between two layers of materials is essential. If one layer of material contains cracks and layers exhibit viscoelastic behavior, determining the properties of the interface becomes challenging. This study proposes a constitutive mechanical law to model the behavior of the interface between a microcracked viscoelastic medium and an undamaged elastic body based on the homogenization method. The interface is modeled by a layer of zero thickness. The coupling between the homogenization technique and the Griffith’s theory is used to provide the effective behavior of the micro-cracked medium. The interface is modelled as an effective medium (EF) characterized by normal and tangential stiffnesses (CN, CT ). In this work, two viscoelastic models are considered, i.e., Burger and Modified Maxwell. The formulas of CN and CT for two cases of crack distributions (isotropic and transversely isotropic) are obtained by asymptotic techniques where the thickness of the joint tends to zero
A study on the capacity assessment of turbo roundabouts and the applicability in Vietnam
Trang: 1544-1554 Nguyen Van Hung, Dang Minh TanTóm tắtA turbo roundabout (or Turbine) is an improvement from conventional roundabouts with lanes running in a spiral shape, helping vehicles to enter the intersection smoothly and eliminate conflicts, reducing traffic congestion as well as the risk of traffic accidents. The turbo roundabout is a modern intersection, newly developed around 1996, initially in the Netherlands, then expanded to many European countries, Russia, and North America. In Vietnam, this type of intersection is still a novelty and requires more scientific exploration. Based on research from developed countries and through the use of Vissim traffic simulation software, the paper presents an analysis and evaluation of the effectiveness of Turbo roundabouts compared to conventional roundabouts. The study also proposed and developed shifted exponential models, capable of well describing the nonlinear relationship between capacity of entry roadway with circular flow. Results show that the turbo roundabout is a potential solution for Vietnamese traffic. The study's evaluation using a basic layout of a two-lane turbo roundabout with only automobile traffic composition limits its applicability to mixed traffic environments. Initially, the study proposes the installation of turbo roundabouts on access roads of freeways, or motor highways with low-to-medium traffic volume
Trang: 1555-1566 Le Xuan Quy, Chu Tien Dung, Vu Tuan AnhTóm tắtThe unique traffic patterns in Vietnam, characterized by a mix of vehicle types, axle configurations, and overloading, pose challenges to current flexible pavement design methods. This study investigates how selecting different vehicle axle load survey data scenarios impacts the accuracy of pavement design and rehabilitation for roads in Vietnam. Evaluation of various data selection methods and their influence on pavement response using the current flexible pavement calculation procedure in Vietnam. By comparing the pavement design criteria calculated under each scenario, this research aims to provide clear guidelines for engineers choosing appropriate axle load data for pavement design. This, in turn, will lead to the design and maintenance of more durable and sustainable pavements, ultimately promoting a more efficient and resilient transportation infrastructure in Vietnam. The research approach involves analyzing various axle load survey data scenarios, including those representing typical traffic conditions, overloaded vehicles, and specific vehicle types. The calculated pavement responses under each scenario are then compared to assess the impact of data selection on design outcomes. This study's findings are expected to provide valuable insights for pavement engineers in Vietnam, enabling them to select appropriate axle load data for accurate pavement design and rehabilitation. This will contribute to building more durable and sustainable road infrastructure, resulting in a more efficient and resilient transportation network
Validation of stamper device to measure international roughness index IRI
Trang: 1567-1580 Phan Thi Thu Hien, Nguyen Thi Hong Hanh, Pham Hoang KienTóm tắtMeasuring International Roughness Index (IRI) is one of the tasks in the process of checking, monitoring and evaluating road surface quality. In Vietnam, the types of IRI measuring devices are still limited. There are specialized devices with high accuracy and speed, but the cost is high. Therefore, they are not commonly used for regular monitoring. To measure IRI regularly and conveniently, it is necessary to use device that is easy to use, convenient, with high speed, high accuracy, but at a reasonable cost. The STAMPER (System with Two Accelerometers for Measuring Profile, Enabling Real-time data collection) from Taisei Rotec company (Japan) has been used to measure on different types of roads in Hanoi: city road, expressway and national highway. Data will be collected many times, with speed ranges and by many types of vehicles. The results show that STAMPER can measure IRI quickly and stably. It is easy to install on many type of vehicles and gives accurate, reliable measurement results
Performance evaluation of bus stops on arterial roads in Hanoi city
Trang: 1581-1592 Tran Khac DuongTóm tắtThe operations of critical bus stops on arterial roads substantially influence the facility bus capacity and the bus quality of service in terms of schedule reliability. The aim of this article is to employ the methodology in the Transit Capacity Quality of Service Manual (TCQSM) to better understand the performance of key bus stops on arterial roads in Hanoi city. The obtained results shown that the capacities of most examined bus stops (Bus Stops 02, 03, and 04) are considerably lower than the actual demands of buses on the considered roads, and increasing the number of loading areas at bus stops is one of the feasible solutions to effectively improve the capacity of bus stops in Hanoi city. The results achieved provide urban transport management agencies and public transport practitioners in Vietnam with a valuable tool for bus stop capacity measurement and additional information for bus quality of service improvement
Real-time estimation of vehicle inertia parameters based on Kalman-bucy filter
Trang: 1593-1603 Nguyen Tuan AnhTóm tắtVehicle inertial parameters such as mass and moments of inertia are required for most vehicle dynamic control systems. Due to the wide range variation of these parameters during vehicle operation, accurate estimation of their values in real-time plays an important role in improving the efficiency of vehicle control systems. In this article, the vehicle sprung mass and moments of inertia are estimated in real-time based on a Kalman-Bucy filter algorithm designed for a spatial vibration model of a two-axle truck. This proposed method requires measuring only the vertical, roll, and pitch velocity of the sprung mass and, therefore can reduce the sensor cost significantly. The simulation results for a random roughness road profile according to ISO 8608 class C with step variations in sprung mass and moments of inertia showed that the designed estimator rejected the process and measurement noises and tracked the real vehicle parameters effectively with acceptable errors
Enhanced-GA supports traffic signal optimizations and protects the urban environment
Trang: 1604-1616 Do Van Manh, Tran Quang Hoc, Le Khanh Giang, Tran Duc Cong, Vu Ngoc PhuongTóm tắtMuch current research on traffic signal optimization often neglects the impact of environmental factors in urban areas. This can result in suboptimal solutions that do not consider the effects of traffic on air pollution and the overall urban environment. To address this issue, this article proposes a solution that combines Enhanced GA with a comprehensive framework for considering environmental factors in traffic signal optimization. By optimizing traffic signal timings and minimizing emissions, the proposed solution aims to reduce congestion and improve urban transportation networks' efficiency while protecting the environment. The proposed approach uses a set of optimization algorithms and assumptions to generate a comprehensive framework for traffic signal optimization. These algorithms and assumptions consider environmental factors such as air quality and the impact of traffic on the local ecosystem. Moreover, this article provided the enhanced genetic algorithm operators and suggested model formulation that could be applied in other research on traffic signal optimization directly to reduce calculation times and increase the efficiency of the novel suggested models
Trang: 1617-1630 Van Tao Le, Tien Long Banh, Thi Hong Minh Nguyen, Tien Dung Hoang, Van Thuc Dang, Hoang Cuong PhanTóm tắtIn electro-discharge machining (EDM) with mixing powder, it is called powder mixed electro-discharge machining (PMEDM), then machining performances- i.e. material removal rate(MRR) and tool wear rate (TWR) has great significance in evaluating the effectiveness and machining accuracy of the machining method. Therefore, in this study, response surface methodology (RSM) was utilized for estimating functions of process variables {comprising peak current (Ip), pulse on time (Ton), and powder concentration (Cp)} for the machining performances for processing SKD61 steel during EDM process with tungsten compound powder. Box-Behnken matrix was utilized for designing and conducting a series of empirical trials. Analysis of variance (ANOVA) was applied to evaluate the adequate of predictive models. The outcomes reveal that the predicted models of MRR and TWR have a high precision with R2 values of MRR and TWR being 99.2% and 99.11%, respectively. The error comparison of the predictive and empirical values for the confirmed experiments is less than 5%, this once again consolidates that the developed models' accuracy. These development models can efficiently prognosticate the desired machining performances of the PMEDM method for processing SKD61 steel
What push students to use motorcycles? A study based on some universities in Hanoi, Vietnam
Trang: 1631-1643 Thuy Linh Le, Thanh Chuong NguyenTóm tắtSo far, little is known about the determinants of the intention to use motorcycles among the young generations in developing countries. This study has proposed an extension of the Theory of Planned Behaviours (TPB) to investigate various factors associated with the motorcycle use intention of students in Hanoi, Vietnam. The data from 399 students from three universities were collected and utilized. The methods used included exploratory factors analysis (EFA) and binary logit regression. Among six latent constructs found in EFA, independence & enjoy, norms & modernity, and convenience & parsimony fuel the intention while others were insignificant predictors. Students who are migrant and come from richer households had higher intention to use motorcycles whereas other demographics such as gender and vehicle ownership were irrelevant. A concerning result found was the positive association of the intention to use motorcycles and cars. Based on the found effects of influential factors, an array of policy implications were suggested
Implement quantum random number generation on the IBM quantum computer platform
Trang: 1644-1658 Nhu Quynh Luc, Van Anh LeTóm tắtRandom numbers are a crucial component of any encryption activity in modern cryptography. Quantum Random Number Generators (QRNGs) produce truly random output strings to replace pseudo-random ones. The principle of QRNG relies on measuring qubit states, which excel in quantum computing applications, particularly on IBM's quantum computing platform. To construct a random number generator, the authors utilized IBM Q Experience's Qiskit quantum development toolkit. We developed QRNG applications on IBM quantum computers (7-qubit, 16-qubit, and 127-qubit) and tested the program's functionality on these quantum computing platforms. The quality assessment of the random strings was conducted according to NIST and AIS-31 standards. For NIST standards, to achieve good quality, the output string must reach a minimum of 1,593,088 bits to pass 16 tests per SP800-22 standard. According to AIS-31 standards, to achieve good quality, the output string must reach a minimum of 8,000,000 bits to pass 8 tests of the standard
Lane detection using hough transformation and Yolov8
Trang: 1659-1672 Nguyen Viet Bach, Pham Xuan TungTóm tắtAutonomous vehicles necessitate the integration of advanced technologies such as computer vision and deep learning to comprehend and navigate their surroundings. A crucial yet challenging component of this integration is the accurate detection of lanes, which can be influenced by a multitude of varying lane characteristics and conditions. This research undertakes a comparative analysis of lane detection methodologies, explicitly focusing on traditional image processing techniques and Convolutional Neural Networks (CNNs). The evaluation utilized a sample of 500 images from the CULane dataset, which encompasses a diverse range of traffic scenarios. Initially, a method incorporating Gaussian blurring, Canny edge detection, and Hough line transformation was examined. Despite its efficiency, operating at 30 frames per second, this approach exhibited a high error rate (average Mean Squared Error (MSE) of 0.537), which is attributable to the loss of critical image details during the preprocessing stage. Subsequently, the performance of a fine-tuned YOLOv8 model, trained on a reformatted version of the CULane dataset was assessed. The combination of object detection and subsequent Hough transformation yielded high accuracy, demonstrating the model’s ability to learn and identify relevant lane features. The deep CNNs demonstrated superior performance over classical image processing techniques in terms of lane detection accuracy, thereby underscoring their potential applicability within the realm of autonomous vehicle technology
Applying a two-step cluster algorithm in traffic accident data analysis
Trang: 1673-1687 Khanh Giang Le, Ho Thi Lan Huong, Van Manh Do, Quang Hoc TranTóm tắtCluster analysis is often employed as the initial stage in organizing heterogeneous data into homogeneous groups. Choosing an effective clustering approach and an ideal number of clusters in a traffic accident dataset might be complex and challenging. This study aims to evaluate the effectiveness of k-means and two-step cluster methods. Subsequently, the two-step cluster method and GIS are applied to analyze the traffic accident datasets from 2015 to 2017 in Hanoi, Vietnam. First, according to the Silhouette score, the two-step cluster method achieved a higher score of 0.563, while the k-means method scored 0.341. A higher Silhouette score indicates more well-defined clusters. Second, the research suggests combining the two-step cluster method with GIS for analyzing traffic accident datasets. The outcome identifies five typical types of accidents in Hanoi. In addition, the locations of various accident types were visually illustrated on a map, enabling traffic officials to recommend precise and urgent countermeasures. Importantly, the clustering results reveal that the two-step cluster method exhibits a significantly higher rate of homogeneous data in the clusters compared to the k-means method. This study demonstrates that the two-step cluster method is not only more effective than the k-means method in terms of clustering ability but also in data pre-processing. The study's results enable authorities to gain a more detailed understanding of typical traffic accident patterns in Hanoi. Besides, the employed methods could potentially be applied to other regions, providing an additional avenue for analysis
Trang: 1688-1696 Vu Kim Hanh, Vu Phuong ThaoTóm tắtThe Free Water Surface wetland (FWS) has emerged as a promising technological solution for wastewater treatment in natural environments. The study aimed at investigating the performance of a laboratory-scale Free Water Surface wetland (FWS) unit designed to treat domestic wastewater with a daily capacity of 20 liters. This model can be applied at some rest stops towards creating "Green Rest Stops" on highways. The laboratory experiments on bronze banana plants have shown that the model operates effectively under specific settings and with the characteristics of residential wastewater from public toilets, which has undergone pretreatment through septic tanks. These conditions are conducive to promoting healthy growth in the plants. The FWS model for cultivating canna hybrid plants (Canna generalis) has a total surface area of 0.26 square meters and operates based on the principles of free wastewater flow. The model has a water retention duration of 70 hours, approximately three days. The treatment efficiency for TSS, BOD5, NH4+ - N, and Coliform is 37-53%, 73-77%, 41-46%, and 37-54%, respectively. The treated wastewater complies with the National technical regulations on water quality, QCVN 14:2008/BTNMT (B) standards
Trang: 1697-1706 Hoang Nam Binh, Le Van Nghi, Hoang Vu HuyTóm tắtFloods are one of the most significant devastating natural hazards around the globe. Recent development in remote sensing technology supports faster and low-cost analysis of flood hazards. This study used the Sentinel-1 SAR data for flood mapping and damage assessment. We selected the October 2022 flood event in Thua Thien Hue province, Vietnam. The Change Detection and Thresholding (CDAT) method was adopted to detect the inundation areas. The results showed that The flood event affected to several districts with Quang Dien being the worst hit, followed by Phu Loc and Huong Tra. Phu Vang had the smallest flooded area. The total inundated area was up to 33,384.08ha. The derived flood map was overlaid onto the current land cover map to conduct an initial evaluation of the potential flood damage corresponding to each land use category. The damage to the land cover was estimated that most of the affected areas were in the cropland and accounted for 77.07% of the total inundated area. The results can assist decision-makers in monitoring and assessing flood damage in Central Vietnam
