基于GIS及耦合协调原理的长输管道山洪泥石流风险性评价

山洪泥石流是影响山区长输油气管道安全运营的主要地质灾害,开展长输油气管道山洪泥石流灾害风险评价有助于预防和减轻其所造成的损失。为此,以兰成渝长输油气管道广元段为例,基于耦合协调原理,将风险评价总系统分解为管体和自然环境2个子系统,前者包括埋深、夹角(管体与斜坡单元夹角)、壁厚、缺陷密度、位置(管体距斜坡单元距离)共5个指标,后者则包括坡向、坡度、高程、植被覆盖指数、年平均降水量、高差、地形剖面曲率、距断层距离、地质岩性等9个指标,利用熵权法确定了不同指标的权重,进而结合GIS技术构建系统耦合协调模型,确定了该区长输管道的风险等级。研究结果表明:①耦合协调度与风险度具有较好的一致性;②研究区南部区域管道的风险度和耦合度均偏高,该区的自然环境、地质构造和气候变化更易诱发山洪泥石流自然灾害;③管体子系统中的缺陷密度、自然环境子系统中的归一化植被指数(NDVI)分别占最大权重,广元段管道应加强管体损坏与植被变化监测。结论认为,该评价方法能迅速而准确地反映现场实际情况,可以较好地应用于管道风险评价。

Risk assessment on mountain torrents and debris flows along long-distance pipelines based on the GIS and coupling-coordination principle

Debris flows and mountain torrents are the main geologic disasters affecting the safe operation of long-distance oil and gas pipelines in mountainous areas. It is of great significance to carry out risk assessment on the disasters of debris flows and mountain torrents along long-distance oil and gas pipelines to prevent and alleviate the losses. In this paper, the Guangyuan section of the Lanzhou–Chengdu–Chongqing long-distance oil and gas pipeline was taken as the research object. Based on the coupling-coordination principle, an overall risk evaluation system was divided into two subsystems, i.e., a pipe subsystem and a natural environment subsystem. The pipe subsystem includes 5 indicators: depth, included angle (included angle between pipe and slope unit), wall thickness, defect density and position (distance between pipe and slope unit). The natural environment subsystem includes 9 indicators: slope direction, slope, elevation, normalized differential vegetation index (NDVI), annual average precipitation, height difference, topographic section curvature, distance between pipe and fault, and geological lithology. Then, the weight of each indicator was determined by means of entropy weight method. Finally, the coupling-coordination model for the system was established by using the GIS technology, and the risk level of the long-distance pipeline in this area was defined. And the following research results were obtained. First, the coupling coordination degree is better accordant with the risk degree. Second, the risk degree and coupling coordination degree of the pipeline in the southern part of the study area are higher, which indicates that the natural environment, geological structure and climate change in this area tend to induce natural disasters easily, e.g. mountain torrents and debris flows. Third, the weight of the defect density of pipe subsystem and that of the NDVI index of natural environment subsystem are the highest, so it is recommended to strengthen monitoring pipe damage and vegetation change in the Guangyuan pipeline section. In conclusion, this evaluation method can reflect the actual field situations rapidly and accurately and it is better applicable in pipeline risk evaluation.