“…In order to grasp the loading and deformation characteristics of shallowly buried pipelines in the surface subsidence area, at present, scholars at home and abroad adopt the foundation beam model to simulate the interaction between the pipeline and the soil, divide the deformation between the pipeline and the soil into coordinated and uncoordinated deformations in the process of surface subsidence, establish the pipeline deflection differential equations and the mechanical model, put forward the segment probability integral correction model for the prediction of the surface subsidence, achieve the prediction of the boundary of the subsidence basin, and analyze the stress and deformation distribution law of pipe body in the process of pipe-soil coordinated and uncoordinated deformation in the subsidence area [9][10][11][12]. Meanwhile, the random medium theory has also been applied to study the deformation law of the soil around the pipeline, which can more accurately assess the strain or stress suffered by the pipeline [13][14][15].…”
In recent years, the integrity of the gas pipeline in the coal-gas co-mining subsidence area has become a critical problem, restricting the safe and efficient mining of coal resources. This paper establishes a theoretical model for the safety prediction of gas pipelines in mining subsidence areas based on elastic free theory, constructs a 3D model of pipe-sand soil by using ABAQUS simulation software (2021), analyzes the characteristics of ground surface and pipeline settlement combined with the measured data on-site, and reveals the temporal and spatial evolution law of the pipeline load and deformation under the condition of diagonal intersections of the pipeline and high-strength mining working face. The results show that during the mining cycle, the pipe and the sandy soil body experienced the stage of cooperative deformation, the stage of increasing non-cooperative deformation, and the stage of weakening non-cooperative deformation; the pipe body is most vulnerable to yield failure in the circumferential direction of 180°, 45°, 225°, and 0°; the relative deformation rate of the pipe experienced a slow and rapid increase in the stage, and tends to flatten out when the advancement length is about 1.5–2 times the distance at the taken cross-section. The study’s results are conducive to accurately predicting the pipe failure orientation under high-intensity mining conditions in coal seams, improving the diagnostic efficiency of pipes, and optimizing the advancement speed of the working face.
“…In order to grasp the loading and deformation characteristics of shallowly buried pipelines in the surface subsidence area, at present, scholars at home and abroad adopt the foundation beam model to simulate the interaction between the pipeline and the soil, divide the deformation between the pipeline and the soil into coordinated and uncoordinated deformations in the process of surface subsidence, establish the pipeline deflection differential equations and the mechanical model, put forward the segment probability integral correction model for the prediction of the surface subsidence, achieve the prediction of the boundary of the subsidence basin, and analyze the stress and deformation distribution law of pipe body in the process of pipe-soil coordinated and uncoordinated deformation in the subsidence area [9][10][11][12]. Meanwhile, the random medium theory has also been applied to study the deformation law of the soil around the pipeline, which can more accurately assess the strain or stress suffered by the pipeline [13][14][15].…”
In recent years, the integrity of the gas pipeline in the coal-gas co-mining subsidence area has become a critical problem, restricting the safe and efficient mining of coal resources. This paper establishes a theoretical model for the safety prediction of gas pipelines in mining subsidence areas based on elastic free theory, constructs a 3D model of pipe-sand soil by using ABAQUS simulation software (2021), analyzes the characteristics of ground surface and pipeline settlement combined with the measured data on-site, and reveals the temporal and spatial evolution law of the pipeline load and deformation under the condition of diagonal intersections of the pipeline and high-strength mining working face. The results show that during the mining cycle, the pipe and the sandy soil body experienced the stage of cooperative deformation, the stage of increasing non-cooperative deformation, and the stage of weakening non-cooperative deformation; the pipe body is most vulnerable to yield failure in the circumferential direction of 180°, 45°, 225°, and 0°; the relative deformation rate of the pipe experienced a slow and rapid increase in the stage, and tends to flatten out when the advancement length is about 1.5–2 times the distance at the taken cross-section. The study’s results are conducive to accurately predicting the pipe failure orientation under high-intensity mining conditions in coal seams, improving the diagnostic efficiency of pipes, and optimizing the advancement speed of the working face.
“…Liu developed the probability integral method based on the stochastic medium, which is most widely used in China because of its good universality, the clear physical meaning of parameters, and high accuracy [24]. However, the probabilistic integral method for predicting surface movement deformation under special geological mining conditions (such as multiple coal seams, steep coal seams, and thick loose layers) is not applicable [25][26][27][28][29].…”
In China, gas and oil reserves are very scarce, but coal resources are abundant in the energy architecture, which decides that coal will remain the dominant energy source for a long time in the future. The accurate prediction of the size and extent of surface movement after coal seam mining is of great significance for the safe promotion of production activities in the mine area and the safety of people’s lives and properties in the mine area. The surface movement deformation under thick loose seam conditions indicates the phenomenon of a large subsidence value and influence range. To predict the size and range of surface movement deformation under thick loose layer conditions accurately, a hyperbolic secant model is constructed based on the hyperbolic secant function. For high nonlinearity of the model parameters, the adaptive step fruit fly algorithm (ASFOA) is introduced into the process of solving the model parameters. Simulation experiments are conducted in three aspects: monitoring point antideficiency, antigross error, and parameter stability. The simulation results show that the ASFOA algorithm achieves high accuracy in finding the parameters of the hyperbolic secant model. The hyperbolic secant model was applied to the 11111 working face under the mining conditions of thick loose layer geology in the Huainan mine. The engineering application results indicate that the hyperbolic secant model performs well on the prediction of surface movement deformation under thick loose layer conditions.
“…2 , the fire was caused by a leak in the pipeline.In addition, damage to underground pipelines and leakage of their contents can cause changes in the surrounding geological conditions, such as local saturation caused by pipeline leakage in areas with wet loess soils, resulting in uneven settlement of foundations and causing safety hazards in the surrounding buildings 7 ; At the same time, due to the invisibility of the underground pipelines, their maintenance costs are also high after breakage 8 . Therefore, a good prediction of the deformation of the adjacent pipelines and timely construction response is the key to ensure the successful completion of the project, which has important theoretical and engineering significance for the design and construction of underpass-type tunnels and ensuring the safety of existing underground structures 9 – 11 . Figure 2 Gas pipe leak causes fire.…”
The underground pipeline network in the city is so intertwined that the concealed excavation of a metro station inevitably leads to a series of underground pipelines, causing settlement deformation and further risk of leakage. The existing theoretical methods for analysing settlement deformation are mostly for circular chambers, whereas metro stations have a nearly square cross-sectional form and different construction methods are very different, which have a greater impact on the deformation of the overlying pipelines. In this paper, based on the random medium theory and Peck's formula, the improved random medium model for predicting ground deformation is modified, the correction coefficients λ and η for the influence of different construction methods are proposed, the prediction model of underground pipeline deformation under different construction methods is obtained, and the numerical models of four work methods commonly used in urban tunnel construction: pillar hole method, side hole method, middle hole method and Pile-Beam-Arch (PBA) method are constructed through simulation, and the mathematical analysis software was used to fit the results to the model and obtain the range of correction coefficients λ and η for each of the four methods, and the accuracy and applicability of the theoretical model was verified by combining with actual engineering cases. The influence on the overlying pipes is in descending order: side hole method, pillar hole method, middle hole method and PBA method. The theoretical model provided in this paper for predicting the deformation of pipes in any overlying strata of the tunnel is well suited to the actual project and has a high degree of correlation with the measured results.
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