Study On The Mechanism And Settlement Predicting Of Vacuum Combined Surcharge Preloading In Reinforcing Soft Soil Foundation

With the development of our country's infrastructure, the higher grade way of freeway and aerodrome runway building in soft soil ground become more and more. In the existing methods to reinforce soft soil, preloading and drained is an economical and easily operated method but long time limited. DJM pile, jet grouting pile and gravel pile, which representative the composite-foundation are too expensive. Vacuum combined surcharge preloading is an advanced method which has good treating effect and also can hurdle shortage of any other methods. So this method is widely used in the area of soft soil as well as many existing problem. The development of the theoretic study cannot follow the progress in practical engineering, and many theoretic problems cannot be solved to this day, its mechanics always has much difficulty to explain. Now the design theory and method mainly depend on experience.However, there are many system productions about calculation theory of vacuum combined surcharge preloading, but it mostly followed load pre-pressure idea, and the property of soft soil is also complicated, especially, theological property controlled the quality of the engineering by influencing the post-construction settlement. The results calculated by the uni-dimensional consolidation theory are different from the truth. So it is very necessary to study the mechanics of vacuum combined surcharge preloading.The paper started with the contrast analysis by several different treatment methods and discussed the features of vacuum combined surcharge preloading. Then respectively introduce the mechanics of surcharge preloading, vacuum preloading and vacuum combined surcharge preloading. Then explain the mechanics of the intensity increasing microcosmic and indicate the advantage of his method.Furthermore, this paper narrates the general situation, design program, monitoring program of the experimental segment in a highway. Then the author reveals the distributing disciplinarian of vacuum degree and pore water pressure and the current of horizontal displacement and vertical settlement.Thirdly, based on the actual settlement, the paper forecasts and calculates the post-construction settlement by 3-points method, hyperbola method, exponential curve method, ratiocinative curve method. The calculation results of different methods are compared and analyzed to conclude that hyperbola method is a suitable method to forecasts the post-construction settlement of the experimental segment. These solutions can provide the basis and reference experience on the highway soft treatment.