Construction Parameters Research Articles

Γ-Convergence for Plane to Wrinkles Transition Problem

We consider a variational problem modeling transition between flat and wrinkled region in a thin elastic sheet and identify the Γ-limit as the sheet thickness goes to 0, thus extending the previous work of the first author (Bella et al. in Arch Ration Mech Anal 218(1):163–217, 2015). The limiting problem is scalar and convex, but constrained and posed for measures. For the Γ-lim inf inequality, we first pass to quadratic variables so that the constraint becomes linear, and then obtain the lower bound using Reshetnyak’s theorem. The construction of the recovery sequence for the Γ-lim sup inequality relies on mollification of quadratic variables and careful choice of multiple construction parameters. Eventually for the limiting problem, we show existence of a minimizer and equipartition of the energy for each frequency.

Improving coalbed methane recovery in fragmented soft coal seams with horizontal cased well cavitation

Effective coalbed methane extraction from soft coal seams is essential for mine safety and energy supply. To enhance the extraction efficiency of coal mine methane (CMM) and reduce the risk of gas outbursts in coal mining areas, we developed an original and innovate horizontal well hydraulic cavitation method. A mathematical model that can quantitatively optimize construction parameters and improve the effectiveness of engineering applications was also constructed to calculate the technological parameters of this construction method. This technology differs from traditional approaches by relying on hydraulic erosion rather than water jets, and it can be implemented in cased horizontal wells. Utilizing the mathematical model grounded in porous media theory and Darcy’s law, numerical simulations with COMSOL Multiphysics were conducted and construction parameters optimized. The proposed technology significantly advances safe and efficient coalbed methane recovery, benefiting coal mine safety and environmental sustainability.

Design and construction of a servomechanism using a memory alloy linear actuator

This work shows the design and construction of a servomechanism of a rotator-type joint based on NiTi Shape Memory Alloys (SMA) with an angular position measurement based on a potentiometer sensor and digital electronic position control. The expected application of this prototype is for the use of small charges that emulate the movement of the human being, being bio-inspired and activated by artificial muscles, their potential applications they will be in medical and humanoid robotics. Computer Aided Design (CAD) allows evaluating and validating the most convenient parameters for construction of servomechanism, experimental results validate allowed us to obtain the values of the range of motion ±20° and a maximum torque of 1.01 kg-cm exerted on the axis of rotation for the prototype.

A Genetic Particle Swarm Optimization with Policy Gradient for Hydraulic Fracturing Optimization

Summary Particle swarm optimization (PSO) has been widely developed and applied as one of the important algorithms for optimization problems because of its few control parameters and low complexity. However, conventional PSO has the problem of premature convergence. Most of the control parameters of optimized PSO are adjusted manually, and the technology of adaptive adjustment based on reinforcement learning (RL) is still immature. Therefore, this study proposes a new genetic PSO (GAPSO) with policy gradient (PGGAPSO). The algorithm constructs a strategy neural network as an agent to dynamically output the action probability distribution and passes the action with the highest selection probability to the GAPSO section through the designed action selection function, thereby updating the parameters. The GAPSO section solves the optimization problem based on the new parameters obtained and uses the individual and global optimums obtained from the iterations as inputs to the policy neural network. In addition, an elite strategy is introduced to enhance the exploration capability of the PGGAPSO. Then, the performance of PGGAPSO was comprehensively evaluated using convergence analysis, statistical tests, Friedman rank, and runtime analysis. Finally, PGGAPSO is applied to the construction parameter optimization of hydraulic fracturing. The results show that due to the influence of the number of samples, the optimization performance of PGGAPSO is general in the early stage of iteration but shows excellent with continuous iteration. For unimodal and most of multimodal functions, PGGAPSO shows significant difference and excellence. Additional processes, such as elite strategy and policy gradient (PG), resulted in a 7.3% increase in runtime for PGGAPSO compared with GAPSO, but this additional computational loss is acceptable relative to the improved accuracy. The algorithm does not require an objective function and can be combined with the complex agent model of hydraulic fracturing to optimize the fracturing parameters. In the case of parameter optimization for hydraulic fracturing in the Jimsar sag, the optimized production was increased by more than 10% on average.

Identification of Fracture Extension Modes During Hydraulic Fracturing in Coalbed Methane Vertical Wells: A Case Study From the Southern Shizhuang Area of the Qinshui Basin, China

ABSTRACTThe accurate identification of fracture extension patterns in hydraulic fracturing can provide important guidance for the optimisation of fracturing parameters. In this paper, factors such as effective hole friction and wellbore flow friction during fracturing are fully considered, and a calculation model of net bottom‐hole pressure of fracturing is constructed. By introducing the change rate of net bottom‐hole pressure and the changing characteristics of the fracturing curve, seven fracture extension modes during hydraulic fracturing in coalbed methane vertical wells are established. The accuracy of the identification method is verified by the fracture monitoring and production results in Shizhuang South Block. The results show that fracture elongation is mainly controlled by in situ stress difference, angle between natural fracture and maximum principal stress, coal tensile strength, fracturing time, proppant and angle between other factors. When the fracture construction parameters are fixed, the smaller the difference between maximum and minimum horizontal principal stresses and the smaller the natural fractures and maximum horizontal principal stresses. When the reservoir potential is similar, the effective extension index is positively correlated with the gas production effect, and the effective extension index can effectively judge the fracturing effect. The higher the proportion of effective extension mode, the longer the extension time and the higher the stable daily gas production. The research results provide a method and reference for clearly identifying the fracture extension and the occurrence conditions of different extension modes in the hydraulic fracturing process.

DETERMINATION OF SUBSIDENCE PROFILES OF THE RAILWAY AND HIGHWAY EMBANKMENTS FOUNDATIONS, DAMS AND LEVEES MADE OF SOIL MATERIALS

Purpose. Determination of foundations subsidence of railways, roads, and other embankments, as well as dams and levees made of soil materials during their design, construction, and operation, is mandatory. At the same time, if the foundation is composed of soils with a small modulus of general deformation (silt, peat, peaty, and similar soils), then not only the average subsidence and its unevenness should be determined, but also determine the profiles of subsidence outside the structures. This is because the subsidence of the foundation has the same order as the height of the embankment (dams, levees); therefore, when determining the additional volume of material required for the construction of an embankment (dams, levees), these deformations must be considered. The purpose of the article was to develop an algorithm for calculating the subsidence profiles of railways, roads, and other embankments, as well as dams and levees made of soil materials. Methodology. Theoretical studies of geomechanical processes using analytical and numerical mathematical methods. Analysis and generalization of theoretical research results. Findings. An algorithm is proposed that allows using simple analytical dependencies to determine those necessary for calculation and design, construction and operation parameters of the system "soil base of dams (levees) and embankments made of soil materials with a trapezoidal cross-section and a rigid core": – the lower limit of the compressed stratum; – subsidence of the foundation within the sole of the base of the dam, levees, or embankment. Originality. It is established that the foundation subsidence on the vertical passing through the center of the dam, levees, or embankment with a symmetrical profile is not less than the subsidence on the calculated verticals passing through any point of the dam, levees, or embankment with an asymmetric profile. Practical value. The main practical result of the work is a more complete (compared to the current regulatory documents) consideration of the features of subsidence of the system "dam, levees (or embankment) made of soil materials – soil base" with a significant reduction in the number of calculations. The results we obtained allow us to determine those necessary for the calculation, design, construction, and operation of dams, levees and embankments made of soil materials characteristics.

Influence of variation in construction parameters on the stability of the surrounding rock in soft rock tunnels

Influence of variation in construction parameters on the stability of the surrounding rock in soft rock tunnels

Numerical simulation study on the construction of cut off walls using high-pressure jet grouting based on SPH method

The optimization of parameters for the construction of cut off walls using high spray method plays a crucial role in improving the permeability stability of hydraulic structures and ensuring the safe operation of water conservancy projects. However, limited by existing research methods, there is currently a lack of systematic research on the influence of construction parameters on the quality of cut off walls. This study fully considers the characteristics of high-speed slurry jet and soil dynamic failure in numerical simulation of the construction of cut off walls using high spray method. Based on the SPH method, a two-dimensional plane strain model of high-pressure jet grouting was established, and the influence of aperture, grouting pressure, and hole spacing on the failure process of soil and the quality of cut off walls is systematically analyzed. The results show that the soil mainly exhibits tensile failure under the continuous action of high-speed cement slurry during the construction of cut off walls using high spray method. Reducing the aperture and grouting pressure, as well as increasing the hole spacing, are not conducive to forming a continuous and dense impermeable wall. Compared to grouting pressure, the influence of aperture and spacing on the quality of cut off walls is more significant. When the aperture is 0.6 m, the grouting pressure is 32 MPa, and the hole spacing is 0.8 m, the quality of cut off walls is great. Finally, the simulation results of this paper were preliminarily verified by combining the construction of cut off walls using high spray method in the flood control project in Luotang Township, Jiangxi Province, China. The findings can provide reference for optimizing the construction parameters of cut off walls using high spray method.

Research on prediction of surrounding rock deformation and optimization of construction parameters of high ground stress tunnel based on WOA-LSTM

To accurately understand the deformation behavior of surrounding rock in the jiugongshan No.2 high ground stress tunnel and optimize construction parameters for improved efficiency, on-site monitoring was used to gather data on rock deformation and initial support contact pressure. A WOA-LSTM regression prediction model was proposed, and excavation advance depth was optimized using numerical simulation. The WOA-LSTM regression prediction model demonstrated high accuracy in tunnel deformation monitoring. The absolute errors between predicted and actual values of tunnel settlement and convergence at various measurement points average 2.53− 04 mm and 1.96− 04 mm, with relative errors averaging 2.15% and 2.34%. These results meet the requirements for guiding construction. Additionally, based on the results of numerical simulation calculations, when the step length is 12 m during the construction of high-stress tunnels using the benching method, excavation advances of 2 m and 3 m result in settlement and convergence increases of 35.1% and 63.4%, and 25.5% and 55.2%, respectively, compared to an excavation advance of 1 m. However, no sudden jumps in these values were observed, indicating that with a 3 m excavation advance, the integrity of the surrounding rock remains in good condition, effectively guiding safe and rapid construction methods.

Research on the stimulation mechanism of well shut-in imbibition and parameter optimization during fracturing-flooding

ABSTRACT In the development of low-permeability tight oil reservoirs, fracturing-flooding technology, with its dual advantages of “fracture creation and energy replenishment, and displacement by imbibition,” effectively addresses challenges such as poor water injection and low oil recovery. However, the mechanism of oil-water migration within the reservoir and the enhanced oil recovery during the shut-in imbibition process remain unclear, and the construction parameters are primarily based on empirical data. In this study, focusing on the Y block in the Bohai Bay Basin, eastern China, we conducted dynamic imbibition experiments and utilized nuclear magnetic resonance (NMR) technology to analyze the key factors influencing imbibition-driven oil displacement and the microscopic oil-water migration mechanisms within the pore space. Numerical simulation was then employed to optimize the construction parameters for fracturing-flooding operations. The results indicate that displacement and imbibition primarily occur in medium-sized pores, while the poor connectivity of micro- and small-sized pores leads to suboptimal effects. The shut-in process provides favorable conditions for imbibition displacement, allowing oil in small and medium pores to be further displaced into fractures. The main factors affecting imbibition efficiency include core permeability (optimal range: 1.5 mD to 4 mD), fracture length (approximately 2/3 of the core length), fracturing-flooding fluid concentration (optimal around 0.2%), and shut-in time (optimal range: 24 to 48 hours). Based on production capacity simulations, the optimal construction parameters for the Y block include an injection rate of 1152 to 1440 m3/min, a total injection volume of 20,000 to 25,000 m3, and a shut-in time of 30 to 45 days. The application of these optimized parameters resulted in an increase in the average daily oil production in the Y block from 4.4 tons to 7.7 tons, demonstrating a significant enhancement in reservoir productivity and oil recovery.

Bonding performance and construction parameters of low-rebound shotcrete

Abstract Shotcrete has the advantages of short setting time, high early strength, simple process and flexible operation methods. It is mainly used as temporary support in domestic highway tunnels. This study investigates the development of low-rebound shotcrete for tunnel construction by adding silica fume and fly ash into the mixture. Sandstone and limestone were employed to simulate the surrounding rock. The workability and mechanical properties of the shotcrete were evaluated based on slump tests, rebound rates, compressive strength measurements, and bonding strength tests between the surrounding rock and the shotcrete. Furthermore, the research investigated construction techniques, with an emphasis on spraying distance, shrinkage angle, and wind pressure, and optimized these parameters for practical engineering uses. The outcomes demonstrate that the addition of silica fume enhances the mechanical properties of the shotcrete and reduces rebound. It was discovered that optimal spraying distance was between 1.2 m and 1.5 m, with the optimal wind pressure at 0.5 m, and the ideal shrinkage angle at 6°. Research on low rebound shotcrete is of great significance for improving construction quality, construction efficiency and engineering structural performance, and also meets the requirements of sustainable development.

Investigation of Dynamic-Cyclic, Dynamic-Impact, and Timber-Construction-Relevant Characteristics of Wood–Textile Composites

Wood–Textile Composites (WTCs) are a new type of composite material based on willow wood strips and polypropylene that combines the properties of classic natural-fiber-reinforced polymers with an innovative textile wood design. While the basic quasi-static properties have already been investigated and described, there is a lack of knowledge about the behavior of the material under dynamic-cyclic and dynamic-impact loading as well as in relation to basic wood construction parameters. The present study is intended to contribute to the later use of the developed material, e.g., in architecture. For this purpose, fatigue tests, dart drop tests (impact and penetration), impact bending tests, and embedment tests were carried out. It was shown that embedding wood fabrics in a thermoplastic matrix leads to a significant increase in resistance to impact loads compared to the neat basic materials. It was also shown that the ratio of the failure stress in the fatigue test to the tensile strength of the WTC corresponds to that of other fiber-reinforced thermoplastics at around 70%. The embedment tests showed that WTC has good values compared to neat wood.

Research on the application of a hybrid intelligent algorithm in reducing the negative response of shield tunneling construction

Traditional shield project control relies on manual monitoring and management, which suffers from poor reliability, lag, and other defects. In this paper, a hybrid algorithm based on Bayesian optimization (BO), light gradient enhancer (LGBM), and nondominated sorting genetic algorithm-III (NSGA-III) is proposed to realize intelligent control of shield construction safety. The BO-LGBM-NSGA-III is a multiobjective optimization algorithm that takes cutterhead wear and shield energy consumption as objective functions and the nonlinear mapping function of surface settlement and construction parameters as fitness functions. Based on the Pareto distribution of the optimized backing structure construction parameters, reasonable limits of the control parameters of the shield tunneling machine are obtained. The conclusions are as follows. (1) The R2 of the test set for surface subsidence prediction is 0.916, and the RMSE is 2.655. (2) The proposed method can achieve multiobjective optimization, and the surface settlement, cutter head wear, and shield energy consumption are optimized by 49.92%, 24.38%, and 41.88%, respectively. (3) By using this method, both prediction and optimization can be realized, and the optimal control scheme can be obtained. The negative impact of shield tunneling construction has been significantly reduced.

Study on the effect of structural parameters of a thermal liner on its thermal protective performance under radiant heat exposure

To comprehend the impact of elementary construction parameters of nonwoven thermal liners on their thermal protective performance, the current research primarily emphasizes on studying the effect of needle penetration depth and needle punch density of the thermal liner. Nonwoven fabrics with three different punch densities and three needling depths were prepared. The air permeability and thermal resistance of the thermal liner were investigated through regression analysis to determine the influence of needle penetration depth and needle punch density. It was observed that both factors had a notable impact on the air permeability and thermal resistance of the thermal liner. An increase in needle penetration depth and needle punch density resulted in a decrease in the air permeability and thermal resistance of the thermal liner. An experiment was carried out utilizing the 33 Box-Behnken designing approach; the factors employed were the radiant heat flux intensity, needle punch density, and needle penetration depth of the thermal liner. The thermal protective performance of thermal liners was measured at three discrete intensities of radiant heat exposures. To investigate the effect of the test and construction parameters and their interaction, an analysis of variance study was carried out. It was observed that protection time rises with the decrease in needling depth and needle punch density at every level of heat flux. With the rise in incident radiant heat flux, protection time declines, irrespective of needle penetration depth and punch density levels.

Efficient Productivity-Aware Control Parameter Optimization in Cutter Suction Dredger Construction Using Machine Learning with Parallel Global Search

This paper proposes an efficient productivity-aware optimization framework that utilizes hybrid machine learning with parallel global search to timely and appropriately adjust the critical control parameters (CCPs) of a cutter suction dredger (CSD) during construction. This optimization framework consists of three main parts. First, a hybrid Jaya–multilayer perceptron (MLP) algorithm was developed to rapidly construct a model that captures the interaction between construction parameters and slurry concentration. Next, the preliminary coarse results for the CCPs are determined through multi-parameter sensitivity analysis. Finally, the proposed resilient-zone parallel global search algorithm was employed to further optimize the CCPs, yielding more precise optimization results. To validate the proposed optimization framework and implement the in-situ service, it is applied to a real-world case study involving “Tianda” CSD construction. The results demonstrated that the average optimization duration is 6.7 s, which is shorter than the data acquisition interval of 8 s. Our approach improves the computational efficiency by 9.4 times compared with traditional optimization control methods. Additionally, there is a significant increase in the slurry concentration, with the maximum growth rate reaching 81.64%.

Super-large diameter slurry shield tunnel encountering boulder formation: Detection, treatment and data analysis

Boulders pose substantial challenges in coastal urban tunnel engineering. This study, for the first time, utilizes extensive closely spaced borehole data from 3486 drilling points obtained during actual tunnelling through boulder strata to evaluate the effectiveness of microtremor detection, analyze variations in operational parameters, and assess the efficiency of blasting treatment. Additionally, leveraging borehole data, a 3D reconstruction of the soil-boulder-bedrock stratum was developed, and the stratum content ratio at the excavation face was derived. A multivariate linear regression model was established to explore the relationship between boulder geology and construction parameters. The results demonstrated that microtremor surveys effectively identified boulder distributions by analyzing horizontal-to-vertical spectral ratio curves and differences in surface wave phase velocity. Field drilling confirmed the high accuracy of microtremor predictions, particularly in areas with dense or thick boulder layers. Post-blasting secondary drilling revealed boulder fragments smaller than 30 cm, meeting the operational requirements for shield cutter and crusher systems. The presence of boulders was found to increase thrust, torque, and overturning moments, as well as cause abnormal cutter wear. Blasting significantly reduced the standard deviation of operational data, demonstrating its effectiveness in stabilizing tunnelling performance. Regression analysis showed a strong correlation between geological conditions and tunnelling parameters, with results indicating that blasting operations effectively mitigate the adverse impacts of boulders on shield tunnelling performance. This study aims to provide valuable insights and references for future engineering projects encountering similar complex geological conditions.

Experimental Study of Synergy between Polymeric Microspheres and Nanoemulsions for Profile Control and Water Plugging.

The development of low-porosity and low-permeability oil reservoirs in the Changqing oilfield presents a significant challenge due to the high injection pressure and limited space for profile control and pressure raising. Therefore, the synergistic profile control and flooding technology of polymer microspheres (PMs) and nanoemulsions is proposed, which makes use of the plugging performance of PMs and the pressure-reducing and oil-driving properties of nanoemulsions, with the objective of controlling the water-absorbing profile and increasing the recovery rate. The paper assessed the properties of nanoemulsions and PMs and evaluated their suitability for reservoirs. The construction parameters of profile control and flooding were optimized on an experimental basis. The experimental results demonstrate that the initial particle size of microspheres can more closely match the pore diameter of the formation and that the core exhibits a higher plugging rate after hydration and expansion. Moreover, the nanoemulsion can effectively reduce the interfacial tension, thereby exerting a beneficial effect on pressure reduction. The construction parameters of microspheres and nanoemulsions were optimized by alternately injecting them with 2:1 multistage plugs, and the injected pressure was lowered by 43%, with a high plugging rate and value-added recovery rate of up to 26.5%. Based on the experimental study, 8 well sets of field tests were conducted, and the results demonstrated that the efficiency rate of profile control reached 50%. Furthermore, the average injection pressure of the injected wells decreased by 1.7 MPa, the rise in water content decreased by 2.27%, and the petroleum production increased by 1110.2 tons. The validity period reached 162 days, indicating a positive application effect.

Characteristics of Vibration Sources and Their Propagation Properties in Shield Construction

The vibration generated during the shield construction process may have an impact on the surrounding environment and structures, so it is particularly important to study the characteristics of its vibration sources and propagation properties. This paper analyzes the characteristics of the main vibration sources of the shield machine during the construction process, including the vibration frequency, amplitude distribution and so on. Through the literature research of various experts and scholars, the change rule of vibration sources under different working conditions is explored, and the propagation characteristics of vibration in the soil body are studied. This study can provide reference basis for vibration control and environmental protection during shield construction. The main conclusions are as follows: 1) the vibration during shield construction is mainly generated by the interaction between the cutter plate and the surrounding rock; 2) the frequency of vibration caused by shield construction is mainly in the range of 0~80Hz, and the amplitude is related to the nature of the excavated soil and the construction parameters; 3) the vibration tends to decrease with the increase of the distance, and the high-frequency vibration propagates faster than the low-frequency attenuation in the soil body.

Content-Adaptive Bitrate Ladder Estimation in High-Efficiency Video Coding Utilizing Spatiotemporal Resolutions

The constant increase in multimedia Internet traffic in the form of video streaming requires new solutions for efficient video coding to save bandwidth and network resources. HTTP adaptive streaming (HAS), the most widely used solution for video streaming, allows the client to adaptively select the bitrate according to the transmission conditions. For this purpose, multiple presentations of the same video content are generated on the video server, which contains video sequences encoded at different bitrates with resolution adjustment to achieve the best Quality of Experience (QoE). This set of bitrate–resolution pairs is called a bitrate ladder. In addition to the traditional one-size-fits-all scheme for the bitrate ladder, context-aware solutions have recently been proposed that enable optimum bitrate–resolution pairs for video sequences of different complexity. However, these solutions use only spatial resolution for optimization, while the selection of the optimal combination of spatial and temporal resolution for a given bitrate has not been sufficiently investigated. This paper proposes bit-ladder optimization considering spatiotemporal features of video sequences and usage of optimal spatial and temporal resolution related to video content complexity. Optimization along two dimensions of resolution significantly increases the complexity of the problem and the approach of intensive encoding for all spatial and temporal resolutions in a wide range of bitrates, for each video sequence, is not feasible in real time. In order to reduce the level of complexity, we propose a data augmentation using a neural network (NN)-based model. To train the NN model, we used seven video sequences of different content complexity, encoded with the HEVC encoder at five different spatial resolutions (SR) up to 4K. Also, all video sequences were encoded using four frame rates up to 120 fps, presenting different temporal resolutions (TR). The Structural Similarity Index Measure (SSIM) is used as an objective video quality metric. After data augmentation, we propose NN models that estimate optimal TR and bitrate values as switching points to a higher SR. These results can be further used as input parameters for the bitrate ladder construction for video sequences of a certain complexity.

A Mesoscopic Approach for the Numerical Simulation of a Mass Concrete Structure Construction Using Post-Cooling Systems

This study introduces an innovative numerical approach to simulate the construction of large concrete structures incorporating post-cooling systems employing the finite element method (FEM). The proposed methodology integrates critical construction parameters, including temperature control mechanisms, while accounting for concrete hydration and environmental conditions. Compared to traditional discrete models, this approach provides similar accuracy with substantially reduced computational costs, enhancing predictive capabilities in the thermal analysis of mass concrete. The method was applied to simulate the construction of a water intake pillar at the Tocoma hydroelectric plant in Venezuela, where the simulated results closely matched in situ temperature measurements. The findings highlight the method’s efficiency and accuracy in simulating post-cooling systems, offering a practical solution for improving the safety and cost-effectiveness in large-scale concrete construction projects.