Search Results (17)

Conventional trenchless pipeline rehabilitation technologies are primarily designed for circular pipelines, with limited applicability to box culvert structures. Even when adapted, these methods often lead to significant reductions in the effective cross-sectional area and fail to enhance the structural load-bearing capacity due to geometric incompatibilities. To overcome these limitations, this study proposes a novel construction approach that employs prefabricated high-strength thin concrete segment liners for the reinforcement of underground box culverts. The feasibility of this method was validated through full-scale (1:1) experimental construction in a purpose-built test culvert, demonstrating rapid and efficient installation. A static stacking load test was subsequently conducted on the reinforced upper section of the culvert. Results indicate that the proposed reinforcement method effectively restores structural integrity and satisfies load-bearing and serviceability requirements, even after removal of the original roof slab. Additionally, a finite element analysis was performed to simulate the stacking load test conditions. The simulation revealed that variations in the mechanical properties of the grout between the existing structure and the new lining had minimal impact on the internal force distribution and deformation behavior of the prefabricated segments. The top segment consistently exhibited semi-rigid fixation behavior. This study offers a promising strategy for the rehabilitation of urban underground box culverts, achieving structural performance recovery while minimizing traffic disruption and enhancing construction efficiency. Full article

As unconventional building structures, container houses are now widely used in urban tourism to create characteristic buildings. Nowadays, natural gas accidents occur frequently in cities and towns; however, the development of laws and influencing factors of natural gas accidents in container buildings have rarely been studied. In this paper, a natural gas explosion test was carried out in an ordinary container house, and a numerical simulation was carried out according to the test results. The influence of methane proportion, ignition position, pressure-relief area, and pressure-relief intensity on the explosion load was analyzed. Research shows that natural gas will gather from top to bottom during the process of leakage and diffusion, and vertical stratification will occur. The most unfavorable working condition is 9.5% methane. Using the roof of the container house as a pressure-relief panel can effectively control the influence range of natural gas explosion accidents and help reduce accident losses. It is suggested that the stacking of container buildings should be reduced as much as possible, and the roof strength should be weakened to ensure structural safety. The research results have certain reference values for the disaster prevention and reduction design of urban characteristic buildings. Full article

The important technical process to ensure the success of gob-side entry retaining by roof cutting (GERRC) was the advanced pre-splitting blasting to cut off the mechanical connection between the roadway and working face roof. The whole-cycle roof structure evolution and stress characteristics of GERRC were analyzed. The factors affecting the roof deformation of GERRC were analyzed, and the quantitative relationship between the roof deformation of GERRC and the support stiffness was determined. The results showed that the temporary support stiffness was higher, the support position to the side of the roof cutting was closer, and the roof subsidence deformation of GERRC was smaller. It is proposed to use a single support mass with a high stiffness to control the deformation of the roof, but it also made the support mass and roof elastic potential energy aggregate. To fully utilize the matching of the support stiffness and roof subsidence, improve the stability, and control the subsidence deformation of the roof in GERRC, double-row stacking supports were adopted in the inclination of GERRC, which were used to increase the stiffness of the support system. Full article

The demand for PV on roof installations in the household sector is increasing. In this paper, an investigation on optimizing the energy performance of PV on housing roofs is conducted. Three housing roof designs found in Gorontalo city are selected as the mounting planes for PV on roofs. The designs represent stacked gable roofs, complex gable roofs, and complex hip roofs. The purpose of the research is to find which roof shape is better for PV mounting in terms of sun radiation gain and access, mountable spaces, and orientation flexibility. This research employs Rhinoceros 3D to model the three roofs. The models are designed to face 12 directions, from 0° to 330°. Radiation analysis using Ladybug is utilized to study the roof’s performance in obtaining solar radiation in all 12 directions. It was found that the complex hip roof has more evenly distributed solar radiation on the roof planes, is flexible for PV mounting in any orientation, but has few mountable spaces. The stacked gable roof has two out of four suitable planes to gain solar radiation, but they are spacious. The complex gable roof has only one out of five suitable planes since they are narrow and prone to self-shading. Overall, a stacked gable roof provides a better option for PV installation compared to the other roof shapes. Full article

Coal mining inevitably brings some negative impacts, such as surface subsidence, aquifer breakage, and land degradation, to the eco-geological environment in the mining area. Among these impacts, coal mining-induced ground deformation is the most serious and has threatened the geological, ecological, and human settlement securities of mining areas. Efforts existing in the literature apply to ground deformation identification in mined-out areas at the meso-/micro and short-time scales. However, when looking back at coal mining history, there are few ways to quickly and accurately quantify ground deformation at the regional and long-time scales. In this context, we propose a method for identifying ground deformation patterns in coal mining areas using historical high-precision digital elevation models (DEMs), including data preprocessing, DEM subtraction operations, interpretation, and fitting correction. This method was applied to the Yulin National Energy and Chemical Base and successfully identified the ground deformation characteristics of the Yulin coal mining area from 2015 to 2019. By determining surface subsidence displacement, excavation depth, stacking height, and the position of the goaf suspended roof area, the objective situation of ground deformation in Yulin mining area was obtained, and the mining methods and distribution characteristics of different surface deformations were analyzed and determined. The research results are of great significance for the development of mineral resources in mining areas, reducing geological disaster risks, protecting the ecological environment, and achieving the goal of coordinated development in mining areas. Full article

Cooling load refers to the amount of energy to be removed from a space (or consumed) to bring that space to an acceptable temperature or to maintain the temperature of a space at an acceptable range. The study aimed to develop a series of models and determine the most accurate ones in the prediction of the cooling load of low-rise tropical buildings based on their basic architectural and structural characteristics. In this context, a series of machine learning (regression) algorithms were tested during the research to determine the most accurate/efficient prediction model. In this regard, a data set consisting of ten features indicating the basic characteristics of the building (floor area, aspect ratio, ceiling height, window material, external wall material, roof material, window wall ratio north faced, window wall ratio south faced, horizontal shading, orientation) were used to predict the cooling load of a low-rise tropical building. The dataset was generated utilizing a set of generative and algorithmic design tools. Following the dataset generation, a series of regression models were tested to find the most accurate model to predict the cooling load. The results of the tests with different algorithms revealed that the relationship between the predictor variables and cooling load could be efficiently modeled through Histogram Gradient Boosting and Stacking models. Full article

Diameters for drainage stacks and vent lines within high-rise building drainage systems are determined by consulting building standard agencies’ design codes. While these are critical design decisions, codes are based upon dated research (1940s to 1970s), which has numerous inherent limitations, and the methodologies employed within the codes are unclear. Thus, a new methodology is presented which is based upon an analogy with other forms of multiphase flow transport systems. This methodology assumes, as a pre-condition, that flows of air and the flow of water within the stack are reasonably steady over time. Component diameters must then be chosen which ensure an acceptably large air supply or air–water flow ratio, and an acceptably small pressure excursion within the stack. Two ways to implement this methodology are presented: an ‘explicit approach’, in which component diameters are directly calculated using empirical correlations, and an ‘implicit approach’, in which component diameters are determined by iteration, using a hydraulic model. The methodology pre-conditions of the approach are then discussed. The physical geometry of the stack and branches tends to promote steady water flow but to render air flow very susceptible to temporary interruptions. A need to maintain the air pathway within high-rise drainage systems using components to supplement the air feed drawn in through the roof vent as required is highlighted. Full article

This article describes the innovative photovoltaic powered seasonal thermal storage—PVPSTS system. It was used in the design of a plus-energy detached single-family house with a usable area of 98 m². This area meets the requirements of the latest building regulations in Poland. The building, with the innovative HVAC installation, was subjected to energy analysis, and a numerical model was also developed. The model was tested based on TMY data for the location of Wroclaw, Poland. Analysis of the results allowed the authors to learn the specifics of the operation of the system throughout the year and to also define its efficiency. The required size of the storage stack was determined to be 1.6 × 1.6 × 0.3 m. The photovoltaic installation, which was integrated with the roof, can produce 48 GJ of electricity per year. This is five to six times more than the building’s heating needs, and any excess energy can be exported to the power grid. Full article

The article is focused on the airflow in a ventilation system in a building. The work examines the methods which enhance the chimney effect. In this paper, three cases with different chimneys were analyzed for the full-scale experiment. These cases were characterized by different geometrical and material parameters, leading to differences in the intensity of the ventilation airflow. The common denominator of the cases was the room with the air inlet and outlet to the ventilation system. The differences between the experimental cases concerned the chimney canal itself, and more precisely its part protruding above the roof slope. The first experimental case concerned a ventilation canal made in a traditional way, from solid ceramic brick. The second experimental case concerned the part that led out above the roof slope with a transparent barrier, called a solar chimney. In the third experimental case, a rotary type of chimney cap was installed on the chimney to improve the efficiency of stack ventilation. All these cases were used to determine the performance of natural ventilation—Air Change per Hour (CH). Additionally, the paper presents a technical and economic comparison of the solutions used. Full article

In this research, a new machine-learning approach was proposed to evaluate the effects of eight input parameters (surface area, relative compactness, wall area, overall height, roof area, orientation, glazing area distribution, and glazing area) on two output parameters, namely, heating load (HL) and cooling load (CL), of the residential buildings. The association strength of each input parameter with each output was systematically investigated using a variety of basic statistical analysis tools to identify the most effective and important input variables. Then, different combinations of data were designed using the intelligent systems, and the best combination was selected, which included the most optimal input data for the development of stacking models. After that, various machine learning models, i.e., XGBoost, random forest, classification and regression tree, and M5 tree model, were applied and developed to predict HL and CL values of the energy performance of buildings. The mentioned techniques were also used as base techniques in the forms of stacking models. As a result, the XGboost-based model achieved a higher accuracy level (HL: coefficient of determination, R² = 0.998; CL: R² = 0.971) with a lower system error (HL: root mean square error, RMSE = 0.461; CL: RMSE = 1.607) than the other developed models in predicting both HL and CL values. Using new stacking-based techniques, this research was able to provide alternative solutions for predicting HL and CL parameters with appropriate accuracy and runtime. Full article

Disparities between fold amplitude (A) and intrusion thickness (H_sill) are critical in identifying elastic or inelastic deformation in a forced fold. However, accurate measurements of these two parameters are challenging because of the limit in separability and detectability of the seismic data. We combined wireline data and 3-D seismic data from the TZ-47 exploring area in the Tarim Basin, Northwest China, to accurately constrain the fold amplitude and total thickness of sills that induced roof uplift in the terrain. Results from the measurement show that the forced fold amplitude is 155.0 m. After decompaction, the original forced fold amplitude in the area penetrated by the well T47 ranged from 159.9 to 225.8 m, which overlaps the total thickness of the stack of sills recovered by seismic method (171.4 m) and well log method (181.0 m). Therefore, the fold amplitude at T47 area is likely to be elastic. In contrast, the outer area of the TZ-47 forced fold is characterized by shear-style deformation, indicating inelastic deformation at the marginal area. It is suggested that interbedded limestone layers would play an important role in strengthening the roof layers, preventing inelastic deformation during the emplacement of intrusive magma. Full article

Humidity-sensitive, demand-controlled ventilation systems have been in use for many years in regions with oceanic climates. Some attempts have been made to apply this technology in Poland, which has a continental climate. This article evaluates the performance and energy consumption of such a system when applied in an eight-floor, multiunit, residential building, i.e., the virtual reference building described by the National Energy Conservation Agency (NAPE), Poland. Simulations using the computer program CONTAM were performed for the whole heating season based upon the climate in Warsaw. Besides passive stack ventilation, that served as a reference, two ventilation systems were studied: one standard and one “hybrid” system with additional roof fans. This study confirmed that the application of humidity-sensitive, demand-controlled ventilation in multiunit residential buildings in a continental climate (Dfb) led to significant energy savings (up to 11.64 kWh/m² of primary energy). However, the operation of the system on higher floors was found to be ineffective. Ensuring consistent operation of the system on all floors required supplementary fans. The introduction of a hybrid mode reduced carbon dioxide concentrations by approximately 32% in the units located in the upper part of the building. The energetic effect in such cases depends strongly on the electricity source. In the case of the national energy grid, savings of primary energy would be relatively low, i.e., 1.07 kWh/m², but in the case of locally produced renewable energy, the energy savings would be equal to 5.18 kWh/m². Full article

The purpose of this research is to determine the most impactful and important source of environmental change at the neighborhood level. The study of multiple scenarios allows us to determine the influence of several parameters on the results of the life cycle analysis of the neighborhood. We are looking at quantifying the impact of orientation, storm water management, density, mobility and the use of renewable energies on the environmental balance sheet of a neighborhood, based on eleven environmental indicators. An eco-neighborhood, located in Belgium, has been selected as the modeling site. The results show that the management of mobility is the parameter that can reduce the impact the most, in terms of greenhouse effect, odor, damage to biodiversity and health. With the adaptation of photovoltaic panels on the site, the production exceeds the consumption all through the year, except for the months of December and January, when the installation covers 45% and 75% of the consumption, respectively. Increasing the built density of the neighborhood by roof stacking allows the different environmental impacts, calculated per inhabitant, to be homogeneously minimized. Full article

Roof collapse and wall spalling in mines commonly occurred. Grouting in the rock mass of a collapsed zone is one of the most effective technologies for solving this problem. Through grouting, the rock mass of a collapsed zone can be cemented into continuous and stable blocks, and the physical and mechanical parameters of the rock mass can be significantly improved. In order to investigate the mechanical properties and damage of rock samples after the injection of a high-polymer material, we conducted uniaxial compression tests in a laboratory on grouted specimens. A high-polymer material is commonly used to address the gangue stacking that is caused by large roof collapse and wall spalling accidents in the mining face and the cracking of coal walls. Research has shown that a high-polymer material effectively solidifies gangues. The results indicate a micromechanics effect of the grouted specimens under uniaxial compression. The compressive strength, fracture propagation, damage mode, and other specimen behaviors are related to the amount of injected high-polymer materials. A high-polymer material substantially improves the mechanical strength of the prefabricated fractured coal and rock mass via strong material adhesion. The vertically- and horizontally-consolidated coal/rock masses exhibit different properties. The use of a high-polymer material results in distinct properties of the consolidated coal and rock masses. Full article

A fast-cure carbon fiber/epoxy prepreg was thermoformed against a replicated automotive roof panel mold (square-cup) to investigate the effect of the stacking sequence of prepreg layers with unidirectional and plane woven fabrics and mold geometry with different drawing angles and depths on the fiber deformation and formability of the prepreg. The optimum forming condition was determined via analysis of the material properties of epoxy resin. The non-linear mechanical properties of prepreg at the deformation modes of inter- and intra-ply shear, tensile and bending were measured to be used as input data for the commercial virtual forming simulation software. The prepreg with a stacking sequence containing the plain-woven carbon prepreg on the outer layer of the laminate was successfully thermoformed against a mold with a depth of 20 mm and a tilting angle of 110°. Experimental results for the shear deformations at each corner of the thermoformed square-cup product were compared with the simulation and a similarity in the overall tendency of the shear angle in the path at each corner was observed. The results are expected to contribute to the optimization of parameters on materials, mold design and processing in the thermoforming mass-production process for manufacturing high quality automotive parts with a square-cup geometry. Full article