摘要:
针对多次爆破振动下现役埋地螺栓法兰管道的安全运营问题，采用精细化模型试验和数值模拟相结合的研究方法，构建了螺栓法兰铸铁管道爆破动力响应模型试验系统，开展了10次爆破试验，分析了螺栓的轴向应变特征、管身和法兰的应变特征。基于模型试验及结果，采用LS-DYNA动力有限元软件，建立了埋地螺栓法兰管道爆破动力响应数值模型，采用磨损理论模型模拟螺栓松动，实现多次爆破计算，分析了埋地螺栓法兰管道的振动速度、应力及法兰偏转角的响应规律。研究结果表明：管道轴向的峰值振速呈现两侧向中间逐渐增大的变化趋势。爆破振动会使螺栓发生松动，螺栓的峰值合速度随爆破次数的增加出现小幅度增大。预紧力的增大会降低螺栓的峰值合速度。管身与法兰连接处出现应力集中，最大有效应力达到157.5MPa。螺帽与螺柱以及法兰的连接部位出现应力集中，最大有效应力达到151.4MPa，爆破后螺栓的应力重分配现象明显。垫片迎爆侧的轴向压力增大，背爆侧的轴向压力减小。法兰偏转表现为迎爆侧压缩，背爆侧拉伸，迎爆侧1#号螺栓处法兰的偏转最大，偏转角为0.029°。
Abstract:
To address the safety operation issues of in-service buried bolted flange pipelines subjected to repeated blasting vibrations, a combined approach of refined model testing and numerical simulation was adopted. A model test system for investigating the blasting dynamic response of bolted flange cast iron pipelines was established, and ten blasting tests were conducted. The axial strain characteristics of the bolts, as well as the strain characteristics of the pipe body and flange, were analyzed. Based on the model tests and their results, a numerical model for the blasting dynamic response of buried bolted flange pipelines was established using the LS-DYNA dynamic finite element software. The wear theory model was employed to simulate bolt loosening, enabling multiple blasting cycle calculations. The response characteristics of vibration velocity, stress, and flange rotation angle of the buried bolted flange pipelines were analyzed. The results indicated that the peak vibration velocity along the pipeline axis gradually increase from the two ends toward the center. The blasting vibrations cause bolt loosening, with the peak resultant velocity of the bolts increasing slightly as the number of blasting cycles increase. Furthermore, increasing the preload is observed to decrease the peak resultant velocity of the bolts. Stress concentration occurs at the connection between the pipe body and the flange, with a maximum effective stress of 157.5 MPa. Stress concentration is also observed at the connection between the nuts, bolts, and flanges, with a maximum effective stress of 151.4 MPa. A marked stress redistribution in the bolts is observed after blasting. The stress on the opposite side of the bolts is significantly lower than that on the blasting side. The axial pressure on the blasting side of the spacer increase, while that on the opposite side decrease. Flange rotation manifests as compression on the blasting side and tension on the opposite side. The flange at Bolt 1# on the blasting side exhibits the largest rotation, with a flange rotation angle of 0.029°.
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