The Karst Development Features And Stability Study For An Aerodrome In Guizhou

To content the needs of economic construction and development,China has strengthened the investment in the traffic construction in the southwest region.In addition to the construction of railway and highway systems,airport construction has also become an effective way to stimulate regional economy.The airport construction belongs to the national important project,has the characteristic of high investment,big project quantity and long period.There are many engineering geological units in the field,and many engineering geological problems are involved,such as karst,groundwater,soft soil,high embankment.Among them,developed karst is more intensively.When the airport pass through karst area in the southwest region,it may encounter various karst hazards,ranging from the impact of investment budget,the impact of weight of the development of the region as a whole.Based on the karst development problems existing in Guizhou Airport extension,the domestic survey methods of karst are deeply investigated and analyzed.Analyzing the development feature of karst by resistivity sounding,seismic image method,ground penetrating radar method and engineering drilling.Though qualitative evaluation and semi-quantitative calculation combine with numerical simulation of nature and high water and airplane loading,karst stability has been evaluated in the field.The results are as follows.(1)Through the preliminary data and field survey,the karst development shows the selectivity to stratum level,tectonic position and geomorphic unit,its mainly develops in the lower Triassic Da'ye and An‘shun formation,and karst are obviously developed along the boundary of bedding lithology,the tectonic direction and the main joint fissure.Besides,the overall development is moderate,especially in fault zone,and the karst form is vertical not horizontal.(2)The development characteristics of covered karst cave are surveyed by comprehensive geophysical prospecting,it includes electrical sounding,geologic radar and seismic image of geophysical methods,and the suspected karst can be verified by engineering drilling.In addition,the F1 fault is deduced by geophysical prospecting and is verified by hole of XK104,which proves the feasibility of geophysical prospecting method in karst survey.(3)Analyzing the stability of the cavern roof with qualitative evaluation and semiquantitative calculation,it is found that make no influence in foundation stability with cavern as the primary,and the unstable is less.The result that by structural mechanic method is higher than roof collapse self-filling method for fracture rock.(4)Calculating the stability of cavern in state of nature and high water and airplane loading by selecting two typical geologic sections,it can be comparative analyzed the differences and changes of displacement,stress,strain,stability coefficient and plastic zone.The results show the stability of nature and airplane loading are higher than high water in I section,and the stability of nature as same as airplane loading,but the difference not very in three working conditions in II section.By simulating and analyzing six working conditions of two typical geologic sections,it is found that the underground caverns has less influence on the stability of the filling and it is a secondary control factor compared with the stability of the embankment.