Construction Site Conditions Research Articles

Investigation of Unsafe Construction Site Conditions Using Deep Learning Algorithms Using Unmanned Aerial Vehicles.

The rapid adoption of Unmanned Aerial Vehicles (UAVs) in the construction industry has revolutionized safety, surveying, quality monitoring, and maintenance assessment. UAVs are increasingly used to prevent accidents caused by falls from heights or being struck by falling objects by ensuring workers comply with safety protocols. This study focuses on leveraging UAV technology to enhance labor safety by monitoring the use of personal protective equipment, particularly helmets, among construction workers. The developed UAV system utilizes the tensorflow technique and an alert system to detect and identify workers not wearing helmets. Employing the high-precision, high-speed, and widely applicable Faster R-CNN method, the UAV can accurately detect construction workers with and without helmets in real-time across various site conditions. This proactive approach ensures immediate feedback and intervention, significantly reducing the risk of injuries and fatalities. Additionally, the implementation of UAVs minimizes the workload of site supervisors by automating safety inspections and monitoring, allowing for more efficient and continuous oversight. The experimental results indicate that the UAV system's high precision, recall, and processing capabilities make it a reliable and cost-effective solution for improving construction site safety. The precision, mAP, and FPS of the developed system with the R-CNN are 93.1%, 58.45%, and 27 FPS. This study demonstrates the potential of UAV technology to enhance safety compliance, protect workers, and improve the overall quality of safety management in the construction industry.

Effects of Light Conditions on Tunnel Construction Workers’ Quality of Life and Work Productivity

Higher lighting intensity promotes workers’ productivity but few studies focus on the problems caused by lower lighting intensities at tunnel construction sites without natural light. The purpose of this study is to explore the relationship between light intensity and workers’ sleep quality, alertness, vitality, and work productivity through a theoretical structural equation model based on the literature review. Data were collected through a questionnaire survey, and 5792 valid responses were adopted for the analysis. First, the results showed that greater lighting intensity promoted workers’ productivity directly and indirectly through three mediators: sleep quality, alertness, and vitality. Then, the whole sample was classified into four groups: high intensity/high comfort, moderate intensity/moderate comfort, moderate intensity/low comfort, and low intensity/low comfort. The clustered results showed that the lighting conditions of tunnel construction sites were generally poor and that lighting comfort promoted workers’ productivity to some extent. Besides, the influence of lighting intensity on productivity declined with improved lighting conditions while the impact of lighting intensity on workers’ physiological and psychological status showed differing trends as lighting conditions varied. However, the relationships between workers’ physiological and psychological status and productivity remained stable regardless of the lighting conditions. The findings could provide a reference for developing corresponding measures to promote workers’ productivity.

Key factors affecting project delivery system selection in the Chinese construction industry

This study aims to investigate the key factors owners consider when selecting a PDS, the importance degree of these factors, and the perception differences among owners, consultants, and contractors regarding these factors. Interviews and questionnaire surveys were used to determine the importance degree of each influencing factor. And perception differences of the influencing factors on PDS among the three subjects were calculated through SPSS 15.0. The findings show that the three subjects' perceptions of the importance degree of the economic attributes of the engineering project, engineering project complexity, sub-project construction interference degree, and delivery system preference were significantly different, while the perceptions of engineering project scale, investment control requirements, schedule requirements, quality requirements, risk preference, construction management capability, land acquisition, demolition and migration, construction site conditions, local policies and regulations, and construction market development level were insignificantly different. This research can help owners understand influencing factors on PDS selection from different dimensions. Valuable information was provided for owners to select an accurate and reasonable PDS, ultimately reducing project costs and facilitating project management. Additionally, this research complements previous research on PDS selection and proposes a new influencing factors framework by exploring the key factors affecting PDS selection and the perception differences between the three subjects.

Physics-Informed Neural Network (PINN) model for predicting subgrade settlement induced by shield tunnelling beneath an existing railway subgrade

For the shield tunnelling beneath an existing railway subgrade, factors such as disturbance during shield tunnel excavation can cause settlements of the existing subgrade above. Traditional prediction methods for subgrade settlement may not fully reflect the construction site conditions. Recently, machine learning has been widely applied due to its fast computation speed and accurate results. However, data-driven machine learning is considered a “black-box” algorithm, lacking a mechanical theory framework and having weak generalization capabilities. To address the limitations of machine learning and enhance the efficiency and accuracy of subgrade settlement prediction during shield tunnel construction, this paper proposes a prediction model based on a physics-informed neural network (PINN). Firstly, by integrating the non-uniform displacement mode function of the tunnel, the physical equations are constructed for the shield tunnel excavation process. Subsequently, the physical equations are coupled with the machine learning framework to develop a predictive model for shield tunnelling beneath an existing railway subgrade based on the PINN model. The performance of the proposed PINN model is evaluated through the application of two engineering cases and compared with traditional numerical simulations and data-driven machine learning. The results indicate that the proposed model can not only predict the settlement of the existing railway subgrade under scant and noisy monitoring data but also have accuracy in the inversion of tunnel displacement mode parameters. Finally, parametric analyses are conducted to reveal the influence of critical variables on the prediction performance of the PINN model.

Synthesis and quantitative structure–activity relationship of unsaturated fatty acid amide propyl dimethyl tertiary amines and their application in clean fracturing fluid thickener in low temperature environment

Solve the problem of freezing and blocking of clean fracturing fluid thickener during winter fracturing operations in the north, which is conducive to improving the efficiency of fracturing operations and oil and gas production rate. In this paper, four kinds of fatty acid amidopropyl dimethyl tertiary amine were successfully prepared and characterized with FT-IR and 1H NMR. Their acid values and Krafft temperature are discussed. The molecular structures of the four kinds of fatty acid amidopropyl dimethyl tertiary amine salts were optimized using Gaussian09 software, then their single point energies were calculated. A quantitative structure–property relationship (QSPR) model was established to predict Krafft temperature of the four kinds of fatty acid amidopropyl dimethyl tertiary amine salts. N-(3-(Dimethylamino)propyl)oleamide (PKO-O), (9Z,12Z)-N-(3-(dimethylamino)propyl)octadeca-9,12-dienamide (PKO-LO) were selected as the main agent. The optimal thickener formulation O1-8 and O2-1 were optimized by single factor experiment and orthogonal test respectively. O2-1 thickener has high low-temperature stability at −5 °C. The viscosity increase property, gel breaking property, rheological property, and viscoelasticity of the clean fracturing fluid obtained by cross-linking O1-8 with O2-1 thickener were evaluated and the properties of O1-8 thickener are better. The result shows that the O1-8 thickener basically meets the conditions of the winter fracturing construction site, and has more practical application significance.

On the Possibility of Controlling the Strength of Soil Cement Elements by the Strength of Soil Cement Pulp

The issue of the possibility of monitoring the results of work on jet cementation by testing the pouring pulp is being considered. A comparison of the results of the strength of the hardened ground cement pulp and the strength of cores from the corresponding ground cement elements made using various technologies with different cement consumption is presented.The results obtained in the conditions of a single construction site composed of soft-plastic loams make it possible to recommend the proposed assessment methodology of the strength of the soil cement to the physician without expensive work on drilling control wells. It is possible to conduct similar studies in different geological conditions.

Possibilities of retarding the setting of PROMPT natural cement by dosing lignosulfonates

Abstract Roman cement (also Natural cement) is a highly hydraulic binder produced by firing limestone rich in clay minerals. A low firing temperature ranging from 800 °C to 1200 °C is typical for Roman cements. This binder has beneficial functional properties: lower CO2 emissions during production, relatively high strength at a lower bulk density compared to Portland cement, resistance against degradation due to salinity, and better durability. A typical property for this binder is fast setting. This is a problem with the application of natural cement in mortars and concretes, as it significantly shortens their workability time in construction site conditions. The beginning of the setting time of mortars based on PROMPT natural cement can be influenced by retarding additives. Citric acid is currently the most used. Citric acid can negatively affect the properties of hardened mortar and its retarding effect may not be satisfactory. The results of the experimental study are presented in this article, where lignosulfonate-based substances were used as setting retarders. It was investigated that selected types of lignosulfonates are effective as a setting retarder. They have, compared to citric acid, a more pronounced effect of delaying the setting. They also have a significant effect on the strength of the hardened mortar after 28, 56 and 90 days.

Analysis of the influence of anchor piles on test results

The paper considers the main problems of design and calculation of deep foundations of high-rise buildings in the form of piles-barrettes. The results and methodology of field tests of barrette piles for the foundation of a 56-storey residential building in Moscow are presented. The characteristics of engineering-geological conditions of the future construction site and design solutions for pilot tests are presented. Given a large cross-section of the barrette, which involves a significant amount of pile-type soil mass with the formation of a complex stress-strain state, to obtain reliable results and verification of the calculated model is recommended to perform numerical tests in full compliance with the field experiment, taking into account the anchored piles. The paper describes the method and the results of the numerical calculation of the load-carrying capacity of a barrette taking into consideration the modeling of an anchoring system in the Midas GTS NX program complex by the finite-element method and shows the basic possibility of using the program complex and the described method for practical purposes with an admissible accuracy. The paper contains diagrams of vertical displacements of a barrette head as a function of the applied load in full-scale tests and a general evaluation of the carrying capacity of a barrette pile obtained by numerical solutions. It is found that by taking into account the anchoring system (beams and piles) in the numerical simulation, the calculation results obtained are the most accurate to the field tests in describing the behavior of the pile under load in comparison with the calculation of a single barrette pile. In spite of the fact that the barrette bottom is embedded into the rocky soils, the barrette piles are referred to the hanging piles according to the interaction conditions with the soil due to the significant load transfer along the lateral surface.

Innovative solution: soil cement column walls as a temporary retaining structure for excavation in soft Bangkok clay

The installation of temporary retaining walls for excavation activities is considered a crucial and costly aspect in the realm of geotechnical engineering construction. Several past studies have been undertaken on the stability aspects of the deep mixing method for soil–cement column walls in soft Bangkok clay are available. However, there has been a lack of research focusing specifically on the relationship between execution time, cost, and stability of these walls, a topic on which this study is focused. The principal aim of this research was to investigate and make a comparative analysis of the stability, construction cost, and construction duration of retaining walls under varying construction site conditions. This study placed particular emphasis on shallow excavation conducted in the context of soft Bangkok clay, and its focus was to determine the most effective construction management strategies within the given contextual parameters. The investigated wall systems comprised of soil–cement columns (SC), stiffened soil–cement columns (SSC), and sheet pile walls. The SC had a diameter of a diameter of 0.6 m, while the SSC was composed of an embedded steel pipe with a diameter of 0.2 m (SSC-IRow Wall). The stability of the walls under investigation was assessed through the utilization of finite element (FE) simulation. The finite element model was initially calibrated through a comparison between the simulation results and the data obtained from field measurements. For a 4.5 m deep excavation with a required factor of safety > 1.3, the SCC and SSCC Walls were found to have an advantage over the conventional sheet pile wall. The SC Wall, consisting of two rows and measuring 7 m in length, demonstrated superior efficiency in terms of both time and cost, regardless of whether it was implemented in unconfined or confined construction sites. The utilization of the SSC-IRow Wall was suggested as an alternative in cases where the use of a thick SC Wall was prohibited. A systematic approach for the selection and design of the SC and SSC Wall systems was proposed, drawing upon a thorough examination and evaluation of the study findings. The results of this study possess the capacity to be utilized in excavation endeavors encompassing diverse depths in the context of soft Bangkok clay and comparable soil conditions.

Deep learning-based object detection for visible dust and prevention measures on construction sites

Activities on construction sites inevitably generate large amounts of dust, which can pose a significant threat to air quality and public health. Detection of construction dust has received increasing attention. In this study, we proposed an object detection method for visible dust and relevant prevention measures on construction sites based on YOLOv7 detector. Deformable Convolutional Networks and Wise-IoU were introduced to improve the precision of the detector in detecting non-rigid objects, such as visible dust. We constructed a publicly available dataset containing 7,500 realistic images covering various construction site conditions. The results indicate that the improved detector achieved high precision with mean average precision of 68.1% and detection speed of 80.6 frames per second. The proposed method enables real-time and effective detection of visible dust and relevant prevention measures on construction sites, which will help advance the research of dust detection and prevention in open space environments.

ANALYSIS OF DOMESTIC AND WORLD STANDARDS REGARDING THE CRITERIA OF THE BOUNDARY STATES FOR THE STEEL SILOS FOUNDATIONS

In the process of operation the structures of steel silos undergo various failures associated with natural and climatic loads and influences, the insufficient study of engineering and geological conditions, as well as some errors during operation. Damage to the above-ground structures of steel silos is mainly caused by roof structures and silo shells failures. Whilst operating silos, various types of raw material flow are distinguished during unloading. Possible scenarios of the operating technology violations can lead to deviations from the approved flow regime during unloading and they quite often become factors of an emergency situation. The conditions of loading and operation of silos have been compared pursuant to their presentation in the domestic and the foreign regulatory documents. A significant number of industrial accidents are associated with operation failures of reinforced concrete foundations, their insufficient load-bearing capacity and their deformability. It should be noted that the construction of the foundation affects its "flexibility", which may cause uneven settlement of the foundations and their base. Sometimes this leads to extra-design loads on the upper structure of the silo. In the domestic practice of increased diameters silos construction, the foundations with an underground gallery are the most common. For the construction areas having a high level of groundwater, the foundations with an above-ground under-silo storey are used. For the silos with an above-ground discharge funnel, the type of outflow influences the load pattern of the foundation. Whilst operating normally, the loads are uniform, and when the storage material hangs on the walls, the loads are uneven, which can lead to the destruction of the above-ground structure or a foundation tilting. The type of funnel significantly determines the shape of the outflow, which affects the distribution of internal forces in the silo and the load on the foundation. In this work, a brief analysis of the failure factors of steel silos has been carried out, and a comparative analysis of modern domestic and international design standards has been suggested concerning the criteria for the occurrence of boundary states of steel silos foundations during designing. There has also been analyzed the special operational features taking into account specific technological loads on silo shells and foundations, the certain features of engineering and geological conditions of construction sites. Conclusions have been made that the main criteria for foundations designing and calculating are the deformation criteria for limiting settlement and tilting. It should be noted that the foreign regulations place the issue of limiting maximum settlements within the scope of a designer's competence. Keywords: reinforced concrete foundation, steel silo, failure, boundary state, design norms.

Mathematical Multiobjective Optimization Model for Trade-Offs in Small-Scale Construction Projects

As construction projects become more complex and challenging to execute, project managers need to develop work schedules that consider as many objectives as are critical to project success. A work schedule designed to optimize all these objectives is likely to enhance project performance. However, achieving a balance among these objectives is difficult because they frequently conflict with each other. Many optimization models have been developed over the years that can factor in different objectives. Although previous optimization studies have contributed to the body of knowledge by individually adding one or two objectives to the classical time–cost trade-off (TCT) problem, none of these studies simultaneously optimized more than three or four objectives at a time. Clearly, there is a need for a multiobjective optimization model to generate work schedules that increase the likelihood of achieving as many project objectives as necessary. This study was motivated by the need to fill this research gap. The objective of this study was to develop a mathematical multiobjective optimization model for the time–cost–quality–schedule flexibility-resource fluctuation trade-off problem in small-scale construction projects. The proposed model is novel because it (1) considers five important objectives of construction project scheduling at the same time, (2) quantifies all objectives to provide an accurate reflection of construction site conditions, and (3) objectively determines the optimal compromise solution using a distance-based method rather than subjectively from a set of Pareto-optimal solutions. The applicability of the proposed model is demonstrated with an illustrative example. The key results of this study are as follows: (1) the optimal solution obtained depends on the project manager’s priorities relative to the objectives; and (2) in optimization problems with more than two objectives, considering the objectives one at a time may result in misleading solutions, because the effects of the other objectives are ignored in this optimization. Consequently, multiple objectives must be considered simultaneously rather than one at a time. The proposed model is expected to provide project managers with a work schedule that balances five or more objectives, increasing the chances of successful project performance.

Research on Installation Technology of Super Large Radial Gate of Dam in Complex Environment

Taking the installation construction of super large radial gates of Nam theun1 hydropower station in Laos as an example, due to the lag of civil construction period and the dam structure, it is not convenient for large lifting equipment to enter the installation face directly. This paper introduces the application of "Bailey beam + Gantry crane" lifting radial gate technology under the conditions of large construction interference, heavy construction task and tight construction period, The installation of super large multi hole radial gate was successfully and quickly realized, which ensured the water storage and power generation schedule of the power station. According to the normal construction sequence, the radial gate of the spillway should be installed normally with large lifting equipment in the open hole state after the civil construction junction, and the upper concrete construction should be carried out after the radial gate is installed. During the construction of the dam and the arc gate, the civil engineering is in the process of sluice construction, the concrete of the dam body is rising, the multi-process and multi-professional construction is intensive, and there are multi-directional intersecting operations, which causes great construction interference. Combined with relevant cases, this paper focuses on the installation technology of super large radial gate in the high temperature and Rainy Zone and the complex environment with limited construction site conditions, so as to provide reference for the implementation of similar projects and actively explore new advanced technology for the industry.

From Risk Assessment on Site to How to Improve Safety: An Easy “App” to Control Construction Site Conditions

A construction site has specific risks and organizational conditions requiring on-site safety inspections. Paperwork inspections have important limitations that can be overcome by substituting paper records with digital registers and using new information and communication technologies. Although academic literature has provided several tools to carry out on-site safety inspections adopting new technologies, most construction sites are not currently ready to adopt them. This paper covers this need of on-site control by providing an application that uses a simple technology accessible to most construction companies. The main objective and contribution of this paper is to design, develop, and implement a mobile device application (App), named "RisGES". It is based on the model of risk that grounds the Construction Site Risk Assessment Tool (CONSRAT) and on the related models that connect risk with specific organizational and safety resources. This proposed application is aimed to assess the on-site risk and organizational structure by using new technologies and considering all relevant resources and material safety conditions. The paper includes practical examples of how to use RisGES in real settings. Evidence for the discriminant validity of CONSRAT is also provided. The RisGES tool is at once preventive and predictive since it yields a specific set of criteria for interventions intended to decrease the levels of risks on-site, as well as to detect improvement needs in the site structure and resources for increasing the safety levels.

Consolidation of loose foundation soil for esplanade project in Kaliningrad

The article presents the practical experience of pre-construction compaction of loose water-saturated clay foundation soils during the construction of Paradnaya Embankment in Kaliningrad. The engineering and geological conditions of the embankment construction site were complicated by the occurrence of a significant thickness (up to 15 m) of highly compressible flowing silts from the surface. The base preparation was carried out by preliminary compaction of loose soils with the ballasting embankment using vertical geodrains. The geotechnical monitoring system at the site was implemented after the construction of the ballasting embankment, in connection with which the designers made a premature conclusion that 90% of the degree of consolidation of soft soils according to the readings of pore pressure sensors was reached only 2 months after the filling of the ballasting embankment. The authors of the article analyzed the calculation methods of the consolidation process used in the design and the results of geotechnical monitoring. A repeated prediction of deformations of the soil mass from its compaction by the ballasting embankment was performed by a numerical method, taking into account the nature of the transfer of the load to the foundation, as well as the presence of shore protection structures of the embankment. A non-standard method was used to assess the total settlement of the ballasting embankment and the degree of consolidation of the foundation in the absence of correct monitoring data, which consists in determining the top elevations of loose soils by drilling control observation wells and comparing them with the results of engineering and geological surveys performed before the start of construction.

Limits and possibilities of thermodynamic modelling of autogenous self-healing of concrete

Autogenous self-healing of water retaining concrete structures is included in Eurocode 1992-3 as a possibility to heal cracks up to a width of 200 μm without additional repair. In this self-healing scenario water flow through a crack should result in a progressive closure of the fracture, mainly due to CaCO3 precipitation, when certain hydraulic gradients are met, the pH of the water is > 5.5 and the concentration of CO2 in the water remains < 40 mg*L-1. The material composition is not further restricted by the regulation. However, despite standardization, the healing effect seems to be random in practice, which requires further research, while experiments aimed at quantifying autogenous self-healing are expensive and time-consuming. Thermodynamic models could support in estimating the effect of different environments such as groundwater or seawater exposure on autogenous self-healing. Moreover, adjusting the water chemistry according to the conditions of different construction sites and changing the material design could easily be considered. In this study thermodynamic models of a hydrated CEM I 52.5 R paste that is exposed to either simulated groundwater or seawater are discussed concerning the influence on autogenous self-healing and compared to experimental and literature data.

Engineering and geological conditions of dam construction

The article presents studies of the engineering-geological conditions of dam construction, consisting of the structure of river valleys and slopes, conditions of rock occurrence, geotechnical and filtration properties of rocks, and geological conditions of the dam construction site. A classification of valley types with schemes, classification of rocks about the location of dams, and types of tectonic structure of valleys about the construction of dams are presented. Conclusions are drawn about the most favorable and unfavorable conditions for the construction of dams.

Optimised technology for repair of vertical surface of concrete bridge elements

Abstract A large number of concrete bridges need to be repaired due to durability problems. This research focuses on evaluating the bond quality of the repair material, which has the highest influence on the durability of the repair. Onsite experimental research is performed on the vertical surfaces of the column of the Klara Jug bridge, which is located in the southern part of the Zagreb. Since the experimental research is carried out in parallel with the ongoing repair works on other bridge elements, the experimental conditions correspond to the real construction site conditions. Simulation of the actual site rehabilitation process was carried out on the test fields, which included removal of the damaged concrete by hydrodemolition at a depth of 1.5–2 cm, washing of the concrete by roto nozzle and wet spraying of the repair mortar. The results of the pull-off tensile bond strength show that there is an optimum period for spraying of repair mortar after washing the concrete surface. Optimal time for application of mortar is 90 min after completion of washing of the vertical concrete surface by the roto nozzle. In other weather conditions, the application time depends on the expected evaporation of water from the surface. The tensile strength of the bond between concrete and the repair mortar is 62% lower if the concrete is not washed by the roto nozzle prior to the application of the repair mortar. This investigation can serve as a practical guide for the repair of vertical surface of concrete elements of bridges, overpasses and viaducts.

Experimental Study on Waterproofing Performance of Segments Based on Sealant Installation Methods

When constructing a tunnel using a shield Tunnel Boring Machine, segments are mainly used. Sealants are then installed at segments for waterproofing. Two types of sealants, a hydrophilic rubber waterstop and a rubber gasket, are mainly used. Sealants can be arranged in single or double layers in consideration of construction site conditions. In this study, waterproofing performance was experimentally evaluated based on the type of sealant and the number of layers. A total of five types of sealant installation methods were tested. Waterproofing performance tests were used to determine their relative waterproofing performances under the same experimental conditions. Results showed that the hydrophilic waterstop was relatively vulnerable to a gap and the gasket was relatively vulnerable to an offset. If double layers of sealants are to be arranged at the construction site, it is recommended to arrange double layers of different types of sealants rather than double layers of the same type of sealants. This study could be helpful for selecting the type of sealant and/or the number of arrays at a construction site.

Digital twin-driven deep reinforcement learning for adaptive task allocation in robotic construction

In order to accomplish diverse tasks successfully in a dynamic (i.e., changing over time) construction environment, robots should be able to prioritize assigned tasks to optimize their performance in a given state. Recently, a deep reinforcement learning (DRL) approach has shown potential for addressing such adaptive task allocation. It remains unanswered, however, whether or not DRL can address adaptive task allocation problems in dynamic robotic construction environments. In this paper, we developed and tested a digital twin-driven DRL learning method to explore the potential of DRL for adaptive task allocation in robotic construction environments. Specifically, the digital twin synthesizes sensory data from physical assets and is used to simulate a variety of dynamic robotic construction site conditions within which a DRL agent can interact. As a result, the agent can learn an adaptive task allocation strategy that increases project performance. We tested this method with a case project in which a virtual robotic construction project (i.e., interlocking concrete bricks are delivered and assembled by robots) was digitally twinned for DRL training and testing. Results indicated that the DRL model’s task allocation approach reduced construction time by 36% in three dynamic testing environments when compared to a rule-based imperative model. The proposed DRL learning method promises to be an effective tool for adaptive task allocation in dynamic robotic construction environments. Such an adaptive task allocation method can help construction robots cope with uncertainties and can ultimately improve construction project performance by efficiently prioritizing assigned tasks.