Research On Karst Growth Law And Foundation Stability Of Some Airport In Panxian,Guizhou Province

The karst distribution in China is widespread,which brings many difficulties to the constructions.With the development of China's economy,new requirements have been put forward for the airport construction in southwest China.Due to the large area of the airport construction site,the engineering geological problems are very complicated because of the large number of hydrological and engineering geological units.Among them,karst development is especially prominent because of its concealment.Especially in guizhou provence,karst distribution is widespread,karst development is strong,and sometimes even becomes the core technical problem of airport construction.Grey fuzzy model based on the theory of grey fuzzy set,using gray level to describe the degree of insufficient information,fuzzy relation is used to describe the relationship between influence factors and karst collapse stability level.Based on previous studies,this paper systematically and comprehensively analyzed the formation conditions,development rules and mechanism of karst collapse,thus determining the influencing factors of karst collapse.In this paper,we can get the following conclusions:?1?Panxian airport is located in edge of the west wing reflex of Puan epsilon type structure,and located in between the Yakou Zhai-Xiadala fault?F4?and Houchangtun fault?F6?,the north wing of Pumoying syncline.The geological mapping of engineering shows that there are two secondary faults in the area due to regional geological structure.?2?In this area,light gray,gray and thin to medium thick layer to fine crystalline dolomite are wide distribution,which belongs to third section?T₂g³?of the Triassic central guanling formation,and the karst development is relatively strong.There are 61 karst cave and 29 ponor in the field.The karst caves are mainly fractured and the karst rate is 5% and the hole rate is 20.2%.?3?The instability of karst foundation in the area is mainly composed of karst collapse instability and karst rock instability.The formation mechanism of karst collapse is the collapse of soil erosion and collapse of karst roof.The main methods of instability of surrounding rock include bending inner drum,shear slip and open collapse.?4?The effect on the stability of the karst foundation is the development of the physical and mechanical properties of rock mass,the structure of state,groundwater development features,structural plane,cave geometry and roof load and artificial factor etc.In this paper,there are 53 caves with stable state,and 59% of the total karst caves.Through the stability calculation,it can be seen that if the cave roof is relatively complete and thick,the results show that it is basically stable.If the roof is more broken and less thick,the stability of the cave is relatively poor.Especially in the karst caves near the tectonic belt,the stability is the worst.?5?This article use the fuzzy comprehensive evaluation model for each field area underground karst cave on stability of the fuzzy comprehensive evaluation,the final evaluation results show that the 90 caves in stability-the karst caves in the relatively stable state,a total of 56,about 62.2%,relatively unstable-instability cave,a total of 34,about 37.8%.Before the result of fuzzy comprehensive evaluation method and qualitative and quantitative evaluation result is consistent,only 4 different evaluation results,shows the results of fuzzy comprehensive evaluation is quite the authenticity and practicality.?6?The mass development of karst can destroy the integrity and homogeneity of foundation rock mass,which can lead to uneven settlement of foundation and ground collapse.For the treatment of surface subsidence,the drainage should be done first,and then the backfill and dynamic co MPaction should be adopted.It is recommended to use filling,crossing,grouting and so on?...