The ground movement simulator: An interesting facility for the study of the behavior of buildings submitted to ground subsidence

Author(s):  
Abdelfettah Fredj ◽  
Aaron Dinovitzer

Pipeline integrity is affected by the action of external soil loads in addition to internal fluid pressure. External soil loads can be generated by landslides or at sites subject to ground subsidence, heave or seismic effects. Under these varied conditions of ground movement potential pipeline safety involves constraints on design and operations. The design processes includes developing an understanding of strains that could be imposed on the pipe (strain demand) and strain limits that the pipe can withstand without failure. The ability to predict the pipeline load, stress or strains state in the presence of soil restraint and/or soil displacement induced loading is not well described in design standards or codes of practice. This paper describes the ongoing work involved in a study investigating the mechanical behavior of buried pipelines interacting with active landslides. Detailed pipe-soil interaction analyses were completed with a 3D continuum SPH method. This paper describes the LS-DYNA numerical modeling process, previously developed by the authors, which was refined and applied to site-specific conditions. To illustrate the performance of the modeling process to consider a translational slide, additional numerical model validation was completed and is described in this paper. These comparisons illustrate that good agreement was observed between the modeling results and experimental full scale trial results. Sample results of the application of the validated 3D continuum modeling process are presented. These results are being used to develop generalized trends in pipeline response to slope movements. The paper describes both the progress achieved to date and the future potential for simplified engineering design tools to assess the load or deformation capacity requirements of buried pipelines exposed to different types of slope movement.


Author(s):  
Andy Young ◽  
Andrew Wilde ◽  
Ivan Grosmann

Abstract Geohazards and external loads are a significant threat to the integrity of pipelines in hilly terrain, at river crossings and where ground subsidence is taking place. Well designed pipelines can tolerate strains that exceed the nominal strain of 0.5% that corresponds specified minimum yield strengths, however the presence of weld defects and stress corrosion cracking can reduce the load capacity dramatically. Welds that are to specification but are under-matched on actual strength to the adjacent parent pipe have also been recognised as potentially vulnerable to low strain failures in high strength pipes. Modern pipelines in terrain susceptible to geohazards normally include design studies to identify and avoid or mitigate the threats. Surveillance of the right-of-way is also routinely carried out for pipelines with good integrity management practices, and particularly for major strategic lines. In-line inspection using an inertial measurement unit (IMU) is a well-known method to detect ground movement loads and contributes to the integrity management of pipelines. In this paper we illustrate : 1. How IMU inspection is an important tool in the management of geohazards and how it compliments other methods of geohazard assessment. 2. How locations of elevated pipe strain are identified and evaluated for external loading threats, and can be aligned with other data sets that indicate the pipeline load capacity. 3. How the locations of bending strain can be prioritised for further action. 4. How the loading profile in the pipeline can be incorporated into crack management strategies in order prioritise locations for further investigation or assessment.


Author(s):  
James Youden ◽  
Desmond Power ◽  
Ping Han ◽  
Jerry English ◽  
Rick Gailing ◽  
...  

Ground movements due to a range of governing mechanisms are recognized to pose hazards to the operating integrity of pipelines in California. As part of an extensive technology management program, Southern California Gas Company (SoCalGas) is involved in the development and implementation of satellite-based monitoring of subsidence ground movements impacting pipeline integrity. By both hosting a Gas Technology Institute (GTI) and Pipeline Research Council International (PRCI) study and undertaking an internal study, SoCalGas is supporting the investigation of two aspects of this promising pipeline integrity management technology. The current project of monitoring ground subsidence due to oil production in the San Joaquin Valley utilizes synthetic aperture radar (SAR) to derive sub-centimeter ground movement measurements from February to September, 2001. The estimates of the subsidence derived from the SAR data are compared with GPS survey results taken at 65 monuments. In addition, archived SAR data from 1992 to 2000 are used to better estimate the movement that has occurred there over the past decade.


Author(s):  
Xiaolin Wang ◽  
Jian Shuai ◽  
Yuanxi Ye ◽  
Shangzhi Zuo

To investigate the effects of mining subsidence on buried pipeline, a computer program to predict three-dimensional ground movement is developed based on Probability Function Integration Method and pressurized pipeline subject to ground subsidence is modeled by using finite element method. Pipeline deformation, stress, strain and the influence of pipeline route are analyzed. The results show that bending combined with compression and twisting results in high stress and strain level for pipeline running athwart subsidence area, while for pipeline parallel to strike or oblique direction of mining gob, obvious twisting is not found and main deformation of pipeline is bending combined with tension which results in lower stress and strain than the former. It is recommended for pipeline design or route selection in mining area that pipeline should be laid parallel to the strike or oblique direction of mining gob in order to avoid complicated deformation.


2017 ◽  
Vol 33 (3) ◽  
pp. 179-200 ◽  
Author(s):  
Ryszard Hejmanowski ◽  
Agnieszka A. Malinowska

AbstractThe modeling of strains and deformations in salt mine areas encounters considerable difficulties because of the varying strength properties of salt, the complex morphological build of dome deposits and the rheological properties of salt. These properties have impacted the development of salt extraction for hundreds of years and the fact that the accurate determining of strains in a given specified moment and place are burdened with high uncertainty. Numerical modeling is useful when the model is reduced to one or several salt chambers. A broader range of underground post mining void considerably lowers the accuracy and efficiency of the calculations of such models. Stochastic models allow for a 3D modeling of the entire mining complex deposit, provided the model has been parametrized in detail. The methods of strains and deformations modeling were presented on the example of one of the biggest salt mines in Europe, where a volume of over 21 million m3 of salt was extracted. The stochastic model could be parametrized thanks to the documented results of measurements of convergence of the underground mining panels and leveling on the surface. The use of land subsidence inversion in the least squares method allowed for estimating the optimum values of parameters of the model. Ground deformation modeling was performed using the two-parameter time function, which allows for a simulation to be carried out in time. In the simulation, the convergence of underground excavations and the transition in time the effects of convergence into ground subsidence was taken into account. The detailed analysis of the geological conditions lead to modeling deviation of the subsidence trough. The accuracy of the modeling results was qualitatively and quantitatively confirmed by a comparison of the modeled to measured values of the vertical ground movement. The scaled model can be applied in future mining extraction projects in order to predict the strains and deformations for an arbitrary moment in time.


2021 ◽  
Vol 13 (15) ◽  
pp. 3044
Author(s):  
Mingjie Liao ◽  
Rui Zhang ◽  
Jichao Lv ◽  
Bin Yu ◽  
Jiatai Pang ◽  
...  

In recent years, many cities in the Chinese loess plateau (especially in Shanxi province) have encountered ground subsidence problems due to the construction of underground projects and the exploitation of underground resources. With the completion of the world’s largest geotechnical project, called “mountain excavation and city construction,” in a collapsible loess area, the Yan’an city also appeared to have uneven ground subsidence. To obtain the spatial distribution characteristics and the time-series evolution trend of the subsidence, we selected Yan’an New District (YAND) as the specific study area and presented an improved time-series InSAR (TS-InSAR) method for experimental research. Based on 89 Sentinel-1A images collected between December 2017 to December 2020, we conducted comprehensive research and analysis on the spatial and temporal evolution of surface subsidence in YAND. The monitoring results showed that the YAND is relatively stable in general, with deformation rates mainly in the range of −10 to 10 mm/yr. However, three significant subsidence funnels existed in the fill area, with a maximum subsidence rate of 100 mm/yr. From 2017 to 2020, the subsidence funnels enlarged, and their subsidence rates accelerated. Further analysis proved that the main factors induced the severe ground subsidence in the study area, including the compressibility and collapsibility of loess, rapid urban construction, geological environment change, traffic circulation load, and dynamic change of groundwater. The experimental results indicated that the improved TS-InSAR method is adaptive to monitoring uneven subsidence of deep loess area. Moreover, related data and information would provide reference to the large-scale ground deformation monitoring and in similar loess areas.


Water ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 219 ◽  
Author(s):  
Antonio-Juan Collados-Lara ◽  
David Pulido-Velazquez ◽  
Rosa María Mateos ◽  
Pablo Ezquerro

In this work, we developed a new method to assess the impact of climate change (CC) scenarios on land subsidence related to groundwater level depletion in detrital aquifers. The main goal of this work was to propose a parsimonious approach that could be applied for any case study. We also evaluated the methodology in a case study, the Vega de Granada aquifer (southern Spain). Historical subsidence rates were estimated using remote sensing techniques (differential interferometric synthetic aperture radar, DInSAR). Local CC scenarios were generated by applying a bias correction approach. An equifeasible ensemble of the generated projections from different climatic models was also proposed. A simple water balance approach was applied to assess CC impacts on lumped global drawdowns due to future potential rainfall recharge and pumping. CC impacts were propagated to drawdowns within piezometers by applying the global delta change observed with the lumped assessment. Regression models were employed to estimate the impacts of these drawdowns in terms of land subsidence, as well as to analyze the influence of the fine-grained material in the aquifer. The results showed that a more linear behavior was observed for the cases with lower percentage of fine-grained material. The mean increase of the maximum subsidence rates in the considered wells for the future horizon (2016–2045) and the Representative Concentration Pathway (RCP) scenario 8.5 was 54%. The main advantage of the proposed method is its applicability in cases with limited information. It is also appropriate for the study of wide areas to identify potential hot spots where more exhaustive analyses should be performed. The method will allow sustainable adaptation strategies in vulnerable areas during drought-critical periods to be assessed.


2020 ◽  
Vol 13 (18) ◽  
Author(s):  
Peng Zhang ◽  
Yajing Pan ◽  
Zhaocheng Yu ◽  
Xiaoming Guan ◽  
Gang Wang ◽  
...  

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