Research On Inducing Mechanism And Countermeasures For Geological Hazards For Highway Projects In Geologically Complicated Areas In Yunnan

In today the road length in Yunnan Province reaches 198,500 Km with expressway length above 2500 Km in end of 2007. However, road with higher technical classification takes only 1/20 of the total, reflecting a huge task for road network upgrading, or, a good opportunity for road development in the province. In such an age that national expressway network access to mountainous regions and rapid development of rural roads, geological conditions have seriously constrained the project schedule and cost and thus impact on operation and transport safety of the road network. Meanwhile, researches on geological hazards in the view of geological environment are neither systematical nor complete. It is very necessary to study the inducing mechanism of and countermeasures towards to geological hazards in geologically complicated areas in Yunnan so that the construction and development of road network in the province could be well-guided.The Paper reviews road development and its characteristics, contribution of road transport to national economy as well as major problems in Yunnan, focusing on geological constraints to road development and geological issues in Yunnan by providing correspondent countermeasures towards geological hazard.The Paper also analyzes complicated geological conditions in Yunnan, such as landform, geological structure environment, active structure, hydrological conditions, geological conditions and geological environment for roads. The paper corresponds and laps all completed and under-constructed highways (with technical classifications above Class II) and mountain distributions, landform zones, land structure zones, huge deep cracks, crust thickness, structure system, new structural activities, major active cracks, earthquake epicenter, regional stability zones, engineering geological zones and expansive soil distributions in the Province. Current researches on countermeasures to geological hazards for highway projects are conducted based on'rapid road development and construction in the last ten years and shall provide guidance for road network development and upgrading in the provmce.The Paper wraps up major disadvantageous geological categories and analyzes geological hazards categories/distributions and geological hazard time-space distribution for road development in Yunnan.The Paper also concludes geological properties, potential dangers, hazard causes and analyzes geological inducing and damages in geologically complicated Yunnan. Meanwhile, the inducing mechanism and inducing chains for highway engineering geological environment are also provided in the Paper.Engineering countermeasures towards geological hazards for highway projects are provided in the Paper in terms of optimization of engineering technologies respectively in landform-related complicated conditions, geological-related complicated conditions, special soil type-related complicated conditions, rock type-related complicated conditions and special geological conditions, and subgrade/bridge technical optimization under special geological conditions.Finally the Paper, through all-round research, provides a prevention and protection form for highway projects under geologically disadvantageous conditions according to alignment selection, hazardous risk assessment, geological investigation, maintenance, hazard treatment and environmental optimization, or, as following,1. For the first time all high-class highways are related to major geological categories with a systematic comparison, which is believed to provide important geological analysis data for highway development in Yunnan. This includes success stories and issues for new road projects and geological countermeasures for new or upgraded road projects.2. Based on local topographic, geological, hydrological and hazardous conditions, a complete countermeasure framework is developed by research on inducing mechanism including geological hazards under natural conditions, construction-related inducing, geological inducing mechanism, and vulnerability and stability assessment as well as technical optimization in landform-related complicated conditions, geological-related complicated conditions, special soil type-related complicated conditions, rock type-related complicated conditions and special geological conditions.3. For the first time geological hazards category and distribution are discussed with their time-space characteristics and development features. Major geological conditions and site assessment methodologies are described in the Paper.4. For the first time causes of geological hazards in highway engineering aspect are discussed by analyzing inducing mechanism from the point view of impact elements, forming mechanism and damage models.5. A set of countermeasures towards geological hazards treatment is developed based on highway subgrade/bridge/tunnel construction and local disadvantageous conditions. Of the measures, Methodology of Side-limit Soft Soil Treatment and Design and Construction Methodology of Hydrophilic Tunnels are developed and plasticized for the first time bringing about favorable social and economic benefits.6. A framework of countermeasures for geological hazards for highway projects is developed considering aspects of alignment selection, geological conditions assessment, geological investigation, maintenance and environmental optimization.7. The research on the countermeasures towards geological hazards helps to construct the corresponding theoretical and methodological system for highway engineering, which is believed to push forward scientific and technical advancement and protection of local geological environment to achieve the best social and economic benefits.