| With the development of China’s economy,“One belt,One road” and the strategy of transportation power are put forward,the scale of the highway construction has been expanding continuously,and the highway construction has been put forward higher request.Yunnan Province is located in the southwest border of China,bordering Vietnam,Myanmar,Laos,between the Indian Ocean and the Pacific Ocean,is an important strategic node of "One belt,One road".In Yunnan,the special soil with soft soil,red clay and expansive soil is widely distributed,which has caused great difficulties in the construction of the project.Based on the Linqing expressway project of Yunnan Province,this paper has carried out two years field monitoring test on the soil characteristics of the bad geological section of soft soil foundation in the valley area.The measured data are more than 20000,and the settlement of the multi-layer soft soil foundation in the valley area is analyzed and predicted,and the finite difference software FLAC3 D is used to simulate the settlement of the subgrade,The main achievements of this paper are as follows:(1)The characteristics of engineering properties of multi-layer soft soil foundation in valley area are revealedAccording to the special engineering geological conditions of the repeated alternate deposition of soft and hard layers of the multi-layer soft soil foundation in Linqing high-speed valley area of Yunnan Province,the formation formation,distribution law and engineering properties of the multi-layer soft soil foundation in the valley area are analyzed;According to the characteristics of stratum and engineering,the soft soil strata in this area are divided into three types: shallow,deep and interlayer;The strengthening mechanism of dynamic compaction cushion method,Pile Load Preloading Method and static pressure pile load method is expounded.(2)Based on the field monitoring data,the settlement and consolidation change of10 typical monitoring sections of subgrade strengthened by dynamic consolidation of soft soil in the complex sedimentary environment of Linqing expressway are analyzedBased on the measured data,the settlement change law and consolidation characteristics of the multi-layer soft soil foundation in the valley area are analyzed;The effect of dynamic compaction cushion combined with static pressure method on the multi-layer soft foundation in valley area is evaluated by static penetration test;According to the feedback of foundation data,the improvement suggestions are put forward for the construction technology of strengthening the multi-layer soft foundation in the valley area by dynamic compaction cushion method;It is suggested that the lateral displacement and stability of foundation should be paid attention to in the construction of deep soft foundation.(3)The spatial and temporal characteristics of settlement of subgrade strengthened by dynamic consolidation of multi-layer soft soil in valley area are simulated and analyzedThe results of the numerical calculation and the measured data are compared and analyzed by FLAC3 D,and the correctness of the model is verified;The settlement characteristics of the multi-layer soft soil reinforced by dynamic compaction in the valley area are revealed;The consolidation law of soft soil foundation is analyzed by settlement pore pressure curve and the consolidation formula is deduced;The paper establishes various working conditions models and analyzes the effect and applicability of different foundation treatment methods for the multi-layer soft soil foundation in the valley area.(4)The development trend of subgrade settlement strengthened by dynamic consolidation of multi-layer soft soil in valley area is predicted by modelingThe basic principle of settlement prediction is discussed,and the advantages and disadvantages of various settlement prediction models are compared and analyzed;Asaoka method is the most sui Tab.settlement prediction method for multi-layer soft soil foundation in valley area;The method of layered summation is modified to predict the settlement of multi-layer soft soil foundation in the valley;It is found that the selection of data samples will significantly affect the accuracy of settlement prediction. |
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