Chunjiao Wang

Climate-Change Impacts on Embankments and Slope Stability in Permafrost Regions of Bei’an-Heihe Highway

China’s Bei’an to Heihe Expressway is located on the southern boundary of high-latitude permafrost, and intersects the north section of the Lesser Khingan Mountain. The geological conditions are extremely complex. In recent years, in this section, roadbed settlement, dribbling icing of roads and cut-slope landslides are increasing, threatening subgrade stability and operational safety. The mechanisms, morphological characteristics and movement of the above phenomena are very different from that in un-frozen areas. These problems are common in highway construction in high-latitude permafrost regions of Northeast China, relevant research has been included in the key research programs of China Communications Construction and international landslide programs (IPL) “Landslides Mechanism and the Subgrade Stability Controlling Measures in Island Permafrost Area (IPL-167)”. Using annual average temperature data from 1954 to 2011 in Sunwu County, the relationship between annual average temperature change and permafrost distribution are analyzed. Based on the data of ground temperature, moisture, surface and landslide deformation monitoring data from 2009 to 2012 in Bei’an to Heihe Expressway K161 + 860 to K178 + 530 section which traverses the north section of the Lesser Khingan Mountain, mountain body landslide and dribbling flow ice on the road area caused by freeze-thaw, as well as landslide mechanism and motion characteristics are analyzed. Results show that: in the past 50 years, the annual average temperature in Sunwu region show a clear upward trend, permafrost degradation has accelerated. Affected by atmospheric precipitation, melting permafrost, seepage water, air temperature, geological condition and human activity, landslides and dribbling flow ice on the road area often occur. These geological problems are controlled by seasonal temperature change, affected by slope water content change, related to geological condition, and have the characteristics of low angle, intermittent, creeping.

Permafrost Distribution Research Based on Remote Sensing Technology in Northwest Section of Lesser Khingan Range in China

Lesser Khingan mountain, located in China, whose northwest section range is near the southern permafrost boundary. In order to study regional surface temperature change, permafrost degradation law and conduct in-depth study of its impact mechanism, using Landsat ETM+imagery as data sources, applying the method of remote sensing thermal infrared, two surface temperature maps have been obtained in study area, the initial permafrost distribution map is formed through ArcGIS software. By analysis of elevation, aspect and slope distribution, the initial permafrost distribution map accordant with on-site investigations and geophysical survey results, which show a clear “Khingan–Baikal type” permafrost features. The research shows that the permafrost distribution maps generation from the Landsat ETM+data by ground temperature inversion in study area can assist permafrost degradation mechanisms research and relative disaster research.

Permafrost Distribution Study Based on Landsat ETM+ Imagery of the Northwest Section of the Lesser Khingan Range, China

The northwest section of the Lesser Khingan Range is close to the southern permafrost boundary in China. Global warming and permafrost degradation have exacerbated local landslides and other natural disasters. Land surface temperature is used as an index of the Earth’s surface energy balance and climate change. In order to study regional surface temperature change and permafrost degradation laws as well as to conduct an in-depth study of their influences, we used Landsat ETM+ imagery and applied remote sensing thermal infrared methods using the ENVI software to calculate surface emissivity. Using the radiative transfer equation method, we produced four surface temperature maps of the northwest section of the Lesser Khingan Range, China. Using the ArcGIS software, we produced two views of an initial permafrost distribution map. Through analysis of elevation, aspect, and slope distribution, the initial permafrost distribution map produced correlates well with on-site investigations and geophysical survey results, showing clear “Khingan–Baikal type” permafrost features. This study shows that the permafrost distribution maps generated from Landsat ETM+ data by ground temperature inversion for the study area can assist research into permafrost degradation mechanisms and the disasters they cause.

Mechanism of Permafrost Landslide Based on GPS and Resistivity Surveying

The formation and development of landslide at K178 + 530 section of Bei’an-Heihe expressway was mainly affected by armchair shape topography of the slope, hydrologic and climatic conditions, frost-heave cycles, and geotechnical engineering activities for highway construction. The study employed data obtained from portable global positioning system (GPS) equipment and high-resolution resistivity profiling to characterize landslide mass dynamic characteristics, stratigraphic log profile of the landslide and analyze the motion mechanism of the landslide in K178 + 530 section of Bei’an-Heihe expressway. Lithologic and geological information were obtained from four monitoring wells drilled along the slope. About 40 GPS gauge piles were placed at different positions on the sliding mass on September 13, 2010, to accurately determine the time, direction and rate of movement at different locations and analyze the role of freezing, thawing and rainfall on the sliding mass. The field monitoring campaign lasted for more than 1 year. Between June, and September 2010, we carried out a high-resolution resistivity investigation to obtain resistivity profile logs of the slope. The results show that the landslide material resistivity profile logs show a significant difference before and after the sliding. Result shows that before the movement of the slope, data obtained from resistivity log shows a uniform signature, while after or during sliding, the resistivity signature changed. The change was due to the development of a slip surface within the landslide mass.

Environmental and Engineering Geology of the Bei’an to Heihe Expressway in China with a Focus on Climate Change

The Bei’an to Heihe Expressway in China is located in southern boundary of high latitude permafrost, and intersects the north section of the geologically complex Lesser Khin-gan Mountains. In recent years, this expressway has experienced increasing roadbed settlement, salutatory flow ice and cut slope landslides in the road area, which threaten the stability of the subgrade and highway operational safety. The morphological characteristics and evolution of the above phenomenon are related to permafrost distribution and degradation as well as seasonal freeze-thaw. The relationship between the annual average temperature change and the permafrost distribution are analyzed based on the annual average temperature from 1954 to 2011 in Sunwu County, which was published by “China National Science and Technology Infrastructure Platform,” and the cumulative monthly average air temperature, ground temperature, precipitation, and maximum frozen soil thickness in Sunwu County from 1971 to 2000. Uneven settlement of the roadbed and salutatory flow ice caused by freeze-thaw, as well as landslide mechanisms and motion characteristics were analyzed. The analysis used ground temperature, moisture, surface and landslide deformation monitoring data from 2009 to 2012 in the Bei’an to Heihe Expressway sections K161+440, K161+860, and K178+530, which traverses the north section of the Lesser Khingan Mountain. The results of this study demonstrates that in the past 50 years, the annual average temperature in the Sunwu region had an upward trend, and after 1995, when the annual average temperature in the region rose to above 0 °C, the permafrost degradation process accelerated. Landslides, roadbed settlement, and salutatory flow ice in the road area are often influenced by atmospheric precipitation, melting permafrost, seepage water, air temperature, geological condition, and human activity. These geological problems are affected by seasonal temperature changes, slope water content change, and other related geological conditions, and have the characteristics of being low angle, intermittent, and creeping.

Occurrence Mechanism and Movement Characteristics of Landslides in Bei’an to Heihe Expressway Area in China Under the Climate Change

In recent years, landslide occurrence is increasing in the section of Sunwu County to Xigang Town where the intersection of the Bei’an to Heihe Expressway and the northwest section of Lesser Khingan Mountain, China, is located. These landslides threat the stability of sub-grade and operation safety. The shape and movement characteristics of these landslides have significant difference with those in other areas. Based on the data of annual average temperature from 1954 to 2011 in Sunwu County, which was published by “China National Science and Technology Infrastructure Platform”, and the data of cumulative monthly average air temperature, ground temperature, precipitation and maximum frozen soil thickness from 1971 to 2000 in Sunwu County, authors analyzed the relationship between the annual average temperature change and permafrost distribution. Based on the geological data, ground temperature, moisture, and landslide deformation monitoring data from 2009 to 2012 of the K178+530 and K177+550 cross section of the Bei’an to Heihe Expressway which pass through the northwest section of Lesser Khingan Mountain, authors comparatively analyzed the landslide formation mechanism and motion characteristics in the Bei’an to Heihe Expressway area combining with the temperature and atmospheric precipitation data of Sun Wu weather station in related time. The study results show that the annual average temperature in Sunwu region shows a clear upward trend in the past 50 years. After 1995, the annual average temperature in the region rises to 0 °C, and permafrost degradation process is accelerated. Landslides occurrence in this road area is the result of the combined effects of atmospheric precipitation, melting permafrost seepage water and geological condition. Sliding process of the landslides in this region is controlled by seasonal temperature change, water content change. It is also related to geological condition with low angle, intermittent and creeping characteristics.

Relative Factors of Beihei Highway’s Ground Deformation Interpretation Based on Remote-Sensing Imagery Technology

Beihei Highway is located in the northern region of the Lesser Khingan Range, near the southern permafrost border of northeast China, which belongs to permafrost belt of high latitudes. The effect of global warming and other natural factors, coupled with urbanization and socio-economic developments has led to continuous melting and structural changes in the permafrost bed and has caused the southern border of the permafrost zone to shift northwards. These changes aggravated the instability of the southern area of the permafrost, one of which is the collapse of a highway embankment which occurred along the Beihei Highway. What threatens the security of the Beihei Highway is that many landslides exist on the highway and most of these landslides are unstable. Remote sensing imagery data from LANDSET ETM + and ENVISAT ASAR were used to study the environmental impact of the highway roadbed slope instability in sensitive and domain area of permafrost degenerate zone and to get the basis for assessment and early warming of deformation, destabilization and other disasters. The authors interpreted and extracted ground temperature, soil moisture and other factors relative to highway deformation. From local survey records, information obtained from weather station and historical imagery from GOOGLE EARTH shows that there is a comparative analysis with interpreted consequences, which can commendably reflect practical ground surface situation and show correlation of various factors. Result may show interpreted consequences’ accuracy for using remote sensing techniques and its fundamental importance for monitoring and early warning deformation disasters caused by climate change and permafrost degradation.

Landslides Characteristic of Northwest Lesser Khingan Range China

Since the late 1990s, with the construction of the highway in Heilongjiang province, the problems of ground deformation and subgrade stability caused by the permafrost have been seriously recognized. Currently, there was little research on Landslides caused by permafrost melting and human factors. We took K177 + 100 to K179 + 300 section of Bei’an to Heihe highway expansion project as the research object. Through site surveys, geological drilling, shallow ground water content and temperature monitoring, slope and subgrade deformation monitoring, laboratory test methods, the formation mechanism of classic landslides in the research area have been comprehensive studied. The results show that: the terrain, geological conditions and the change of moisture content in hillside slope were the main reasons to generate landslides. Atmospheric precipitation, seasonal freezing and thawing of shallow slope ground and the melting of island permafrost scattered in the mountain valley provided continuous landslides water. Artificial disturbance to slope soil in the road construction process accelerated the slope sliding. This research can provide reference for slope design and assessment of similar conditions in northeast China.

Shallow Slope Failure and Protection Method Along a Highway in a Seasonally Frozen Area in China

Shallow slope failure occurred frequently along the Jiamusi-Harbin section of Tong-San highway in Heilongjiang Province (Jia-Ha highway), China in April and May every year since the highway construction involving cut-slopes, in 1997. Because seasonally frozen areas are widely distributed in this area, the melting of frozen soil is thought to be the main reason for the slope failure. We selected two different slopes, one protected by geotechnical countermeasure works of steel–concrete frame but which failed, and another that was protected by biotechnical countermeasure works which included trees, and remained stable, to analyze the possible mechanism of the shallow slope failure at the cut-slopes in this area, and the suitability of the countermeasure works.

Landslide Mechanisms and Protection of Highways in Frozen Regions of Northeast China

Disasters caused by permafrost thawing have increased in permafrost regions in recent years due to changing climate and expansion of human activities. Heilongjiang Province is located in northeast China, where frozen soil is widely distributed. During highway construction, landslides caused by soil freeze-thaw have occurred often, much affecting slope stability and traffic safety. We have studied the effect of seasonal frozen soil freeze-thaw and permafrost thawing on the stability of the highway subgrade and slopes using data from the completed Tong-San highway from Harbin to Jiamusi and the Jihei highway under construction from Bei’an to Heihe. The study was divided into two parts: 1) for the Tong-San highway from Harbin to Jiamusi, the landslide mechanismas well as the protectionmechanism of soil containing woody roots were studied; 2) for the Jihei highway from Bei’an to Heihe, the mechanism of mountain body landslide was studied. These two studies are two IPL projects: IPL 132 (Research on Vegetation Protection System for Highway Soil Slope in Seasonal Frozen Regions), and IPL 167(Landslides Mechanism and the subgrade Stability Controlling Measures in Island Permafrost Area). The research was also funded by the Heilongjiang provincial government and the Chinese Ministry, to a total amount of 400,000 dollars. The work of IPL-132 has been completed, and some research results concerning protection of cut slopes have been adopted by the relevant departments of Heilongjiang Province in highway construction. The work IPL-167 is still ongoing.