| South-North Water Diversion Project (SNWD Project) is a momentous, strategic and fundamental project to optimize the allocation of water resources in China. The project of the PCCP Engineering in Beijing is an important part of the terminal of midline engineering of SNWD Project, where the geological conditions are very complex and the geo-hazards are most developed. The initiation for the geo-hazards is not only related to natural conditions, but also to human activities. With different methods, the paroxysmal geological hazards and gradual changes of geological environment were studied, so as to reduce the geo-hazards and carry through the disaster prevention and mitigation scientifically. And at the same time, the research method for the geo-hazard and its effect on the environment were studied, especially for the significant’Lifeline Engineering’.Based on the data analysis of the domestic and international long-distance inter-basin water transfer, by taking the PCCP Engineering as a case study and by using the various methods such as the numerical simulation method and catastrophe theory, the paroxysmal geological hazards and gradual changes of geological environment were studied to discuss the mechanism of geo-hazard and its effect on the environment. And the following achievements are obtained:(1) The coupling mechanism among the linear engineering facilities of major cities, rock mass, water, human activities and natural geological environment are discussed based on the disclosure of the distribution and formation mechanism for geo-hazards along the part of PCCP Engineering, and the method for geo-hazard risk management are put forward; the prevention strategies and treatment measures for typical geo-hazards across river and road and other poor geological conditions, which will supply basis for safe operation and maintenance for project.(2) With various method such as numerical simulation and catastrophe theory, the comprehensive evaluation for collapse, landslide, mud flow, karst, rainstorm, flood, freeze thawing, sand soil liquation, burst for linear project have been done. And with the help of software FLAC3D and GeoStudio, the stability for rock and soil slope suffering load and rainstorm are analyzed. The simulation results indicate that, the slopes are stability not considering other factors but pipeline transportation vehicle load. However, the safety factor of soil slope reduces to the critical condition when considering the rainstorm, which is consistent with the fact. Some related protective measures and control methods are put forward so as to reduce the geo-hazards and carry through the disaster prevention and mitigation scientifically.(3) By using the coupling effect of water and rock and the failure mechanism, the influence of the poor geological conditions and pre-existing conditions on the water diversion project and the interaction are studied, focusing on the occurrence possibility of potential risk when the pipeline crosses the soft soil, loess, sand soil liquation, surface subsidence, railway, highway, river, underground pipeline, etc., especially for the influence and hazard of environmental geological problems such as rock weathering, construction precipitation, soil erosion and water immersion. The protective measures and control methods are put forward for the safe construction and operation of water diversion pipeline.(4) The engineering geological conditions and main problems of rock tunnel and incompact tunnel of water diversion project are analyzed, especially for the collapse and water and mud burst from multiple perspectives, and water seep around tunnel, the corresponding control measures are proposed.(5) The influence of great number of ground structures and underground facilities on the safe construction and operation for engineering in suburban and urban areas are studied, especially for the pipe systems supplying heating, electricity, telephone, sewage, heat, oil, gas, and the subway and so on. The control measures for the potential occurrence of fault and distort caused by the changes of force status and structure of underground installation are analyzed. The correlations between the linear engineering in major cities and the ground structures, cross structures, buried pipelines, protection of cultural relics are also studied, and its safety and social impact are discussed so as to provide references for the study on similar projects. |
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