Study On The Karst Characteristics And Its Disposal Methods Of Subgrade One Expressway

This paper takes Hunan Lou-Xin highway as engineering background,using a Variety of means and methods,studied the Karst development conditions, the Karst distribution Regularity and the effect of highway subgrade and the reinforcement scheme optimization was studied The specific work are as follows:(1) According to Lou-Xin highway roadbed karst landform features, the strata rock properties, weather and hydrogeological conditions and geological structure, it has a the evaluation on the link of the engineering geological And, on this basis, it analyzed the surface subsidence mechanism of roadbed karst cave or soil caves and underground in the forming process of the soil hole, classification, formation conditions and distribution;(2) Taking the new highway K30+987-K31+380links of the cave and soil subgrade holes for example, it calculated the roadbed filling on respectively the influence depth of foundation soil,discussed the influence of depth within the cave and soil cave on the roadbed stability the roadbed filling on respectively the influence depth of foundation soil.The roof collapsed to filling the DongTi karst cave of the required thickness calculation, thick, bending and across the analogy method based on shear checking method of the three sections of the cave and soil caves corresponding contrast analysis. Finally, the safe distance away from subgrade is calculated;(3) On the basis of the above study, it ranalyzed the karst and irregular subgrade treatment of the general principles and the commonly used treatment methods. And then it comparised and analyzed of the karst grouting treatment, sunken tube compaction pile and dynamic consolidation grouting+local double reinforced concrete board three karst processing methods of technical and economic indicators and disposal effect. And according to the application of multi objective decision with fuzzy set theory, and ultimately it determined the research section of the optimal scheme karst subgrade treatment.Through the above work, it provided a theoretical analysis and treatment plan for the new highway subgrade treatment of karst, this scheme also can provide technical guidance or reference for the design and construction of similar projects.