Dynamic failure behavior of buried cast iron gas pipeline with local external corrosion subjected to blasting vibration

The reconstruction and expansion project of oil reserve base often faces the excavation and blasting of the slope and undercrossing tunnel at the same time. Due to the flammable and explosive liquid storage nearby, the tight construction period, and the high requirements of collaborative construction, once the blasting accident occurs, the consequences are unimaginable. To facilitate safe and timely cooperative blasting construction of the slope and undercrossing tunnel, a vibration monitoring test of the slope and tunnel surrounding rock is conducted. The vibration response characteristics of the rock surrounding the slope and tunnel are analyzed, and a mathematical prediction model for the peak particle velocity (PPV) with consideration of the influence of the relative slope gradient (H/D) is established based on dimension analysis theory, which improves the prediction accuracy of PPV at the slope surface. ANSYS/LS-DYNA is used to establish a 3D finite element model for the slope and tunnel, and the dynamic response of the tunnel surrounding rock under blasting load is verified through field monitoring data. A linear statistical relationship between PPV and effective tensile stress (ETS) of the tunnel surrounding rock is established. The PPV safety criterion of the tunnel surrounding rock under blasting load is proposed to be 10 cm/s according to the first strength theory, and hence, the minimum safety distance from the tunnel working face to the slope surface is calculated to be 36 m. Finally, the excavation timing arrangement of the slope and tunnel is proposed, which has been successfully applied to the expansion project, and the construction period has been effectively shortened by 45 days while ensuring construction safety. The research results have great guiding significance to similar cooperative blasting excavation engineering for high slope and adjacent tunnel with safety and efficiency.

Section: Numerical Calculations and Verificationmentioning

confidence: 99%

Prediction of Bench Blasting Vibration on Slope and Safety Threshold of Blasting Vibration Velocity to Undercrossing Tunnel

Zhong

Liu

et al. 2021

“…Xia et al [20] calculated the vibration response of buried flexible HDPE pipes under impact loads based on the Winkler model and the Timoshenko beam theory. Recently, Jiang et al [21][22][23] studied the dynamic failure behavior of buried cast iron gas pipeline subjected to blasting vibration. In order to simplify the analysis, most of these studies approximately regard blasting seismic waves as plane waves.…”

Section: Introductionmentioning

confidence: 99%

Random Dynamic Response Characteristics of Pipeline Subjected to Blasting Cylindrical SH Waves

Zhang

2021

It is essential to investigate the influence of blasting vibrations on pipelines, and the dynamic response is the crux in the safety issues. At present, the blasting seismic wave is usually regarded as a plane wave. However, there is little research about the dynamic response characteristics of underground structures subjected to nonplane waves. The analytical solution to dynamic stress concentration factor (DSCF) of pipelines subjected to cylindrical SH wave was derived. Besides, the randomness of the shear modulus of soil was considered, and the statistical analysis of DSCF was carried out by the Monte Carlo simulation method. Results show that the variability of the shear modulus of soil has a significant influence on the probability distribution of DSCF. The larger the variation coefficient of the shear modulus is, the more obvious the skewness of DSCF is. The influence of low-frequency wave on pipeline increases with the reducing normalized distance r∗, while the influence of high-frequency wave reduces and the variation amplitude of DSCF increases. Compared with the DSCF of pipe subjected to a plane wave, a lower dominant frequency or larger normalized distance for the cylindrical SH wave will generate a more similar statistical characteristic of DSCF.

“…It is well known that the vibration induced by blasting excavation has adverse effects on the surrounding buildings and equipment [8,9]. At the same time, the dynamic loads of rock slope, such as earthquake or blasting excavation, are mostly long-term or periodic [10,11].…”

Section: Introductionmentioning

confidence: 99%

Rheological Properties of Argillaceous Intercalation under the Combination of Static and Intermittent Dynamic Shear Loads

Zhang

Dong

Zhang

et al. 2021

The construction and long-term operation stage of the rock slope with argillaceous interlayer will be subjected to intermittent dynamic loads, such as blasting and earthquake. For the argillaceous interlayer in the rock slope, its rheological properties are not only related to the initial stress state caused by the gravity of the overlying rock mass but also affected by intermittent dynamic loads. In order to investigate the rheological properties of argillaceous intercalation under the combination of static and intermittent dynamic shear loads, the rheological tests of argillic intercalated soil samples under static shear, static and cyclic dynamic shear, and static and intermittent dynamic shear were carried out, and the rheological deformation characteristics of soil samples under different shear conditions were analyzed. The results show that when the soil specimens in the static shear rheological process are disturbed by intermittent dynamic shearing load, the intermittent dynamic disturbances might have no remarkable influence on the rheological deformation of the specimens if the initial static shearing stress and intermittent dynamic shearing stress were comparatively low. However, low-intensity intermittent dynamic disturbances might accelerate the rheological deformation process of the specimens remarkably if the initial static shearing stress state was close to their shearing strength. There was a stress threshold when the soil specimens failed under the static and cycling dynamic shear and static and intermittent dynamic shear, which is determined by the sum of static shear stress and dynamic shear stress peak. For rock slopes controlled by rheological weak structural planes and influenced by long-term blasting vibrations, the transient and long-term dynamic stability should be comprehensively analyzed.