Deformation Characteristics Analysis And Prevention Measures Research Of Soaking Subgrade In High Seismic Intensity Region

Due to the needs of engineering construction, especially in the western mountainous area, expressways built along the rivers and reservoirs will be more and more.the subgrade of these highways are both bearing body and man-made reservoir bank. The stability of the subgrade will inevitably influence on the quality and repair difficulty and later maintenance projects. Water is the most important factor that endangering the strength and deformation of the subgrade. Soaking Subgrade that under the action of water impact, erosion, soften and water level fluctuation will influence the safety of highway.Which will cause Subgrade deformation damage and slopefailure. And influencing driving safety or even interrupted transport, causing losses of lives and property.China is a large land earthquake country.and terrain and geological conditions is complex, Two-thirds of the homeland is mountainous.Especially in the western areas, terrain change is big and geological structure is complex. Therefore, the engineering construction activities in this region must consider the effects of water and earthquakes, and make the necessary protective measures.This article is based on the Soaking Subgrade of Yalu highway. Through the study on the engineering geological conditions which provide us geological background, And through the field survey, indoor test of subgrade determined the characteristic of the backfilled material. On this basis, the deformation characteristics and protective measures were studied through the limit equilibrium method and numerical simulation method. Obtain the following results:(1) Use finite element method analyzes the typical cross section of the subgrade, the results show: In the natural state, the settlement of the subgrade will get bigger with the increasing of compactedness of backfilled material. This is because the modulus of elasticity of the soil under the subgrade is low, with the increasing of compactedness of backfilled material of the subgrade, the elastic modulus is increase.so, although the settlement of subgrade is decreasing, the compressive deformation of the soil under the subgrade is increasing, and is bigger. So the overall deformation is increased. The horizontal displacement of the subgrade will get bigger with the increasing of compactedness of backfilled material too. This is because with the increasing of compactedness of backfilled material the horizontal load is also on the increase, Therefore, the deformation also increased.but, after the water level rise, because of the water floating force, the effective specific weight is reduce and so is the horizontal load. Finally the horizontal displacement will be relatively decreases.(2) Use discrete element method analyzes the stability of the typical cross section of the subgrade under the effects of earthquake, Results show that: Under various working conditions, Subgrade will become instability and failure under the effects of earthquake. And under the effects of water the intensity parameter of subgrade have a dramatic decline. After the water level rise the stability of subgrade coefficient have come down dramatically. And with the increase of compaction degree, the scope of destruction will be smaller.(3) Through the analysis of the limit equilibrium method, the results show: in the natural state, the subgrade stability is fine; after the water level rise the stability of subgrade have descend, but safety coefficients can still meet the requirements. The waterline will separate the subgrade into two parts. Above the waterline the stability of the subgrade did not change, below the waterline the stability of the roadbad was significantly descended due to the reducing of effective specific weight and the decreasing of shear streagth parameters. In the earthquake effect, the stability fell sharply, the slope of the subgrade is instability and therefore need corresponding reinforcement measures to prevent its collapse.(4) Through the limit equilibrium method and finite element method compare and analyze different design schemes, the results show that, Along with the increase of slope design,The overall stability of the embankment will subsequently reduce,but the range is small. In the natural state, the change of level 3's slope ratio only influences the local deformation of the subgrade, but the change of level 2's slope ratio will influences the overall deformation of the subgrade. But as the ground water level rises, the deformation of the subgrade will become more sensitive to the change of slope ratio.(5) Through physical simulation experiment of vibration of soaking subgrade, we may know frome the experimental result that: Water play an important role during the earthquake. Without water, the subgrade will destroy from inside, along with the continuous of vibration the subgrade's outside will become destroy. But as the ground water level rises, the destruction will occur in the outside first, because of the water waves produced by vibration.(6) Carry on research of protection technology of stability problem of soaking subgrade at home and abroad.And compared the feasibility in prevention projects application. Eventually selected mortar rubble + reinforced earth+monitoring treatment solutions.