Research On Deformation And Settlement Of Decayed Wood And Silt Mixed Soil

Decayed Wood and Silt Mixed Soil (DWSMS) is a special kind of mixed soft soil which has been found in expressway foundation in Zhujiang River delta and coastal zone of east of Guangdong province. Decayed Wood and Silt Mixed Soil can't be ignored in practical project. A systemic research of Decayed Wood and Silt Mixed Soil also is absent in recent years. Therefore, there is important practical significance to study basic settlement indexes of Decayed Wood and Silt Mixed Soil, which will direct the design and construction of similar soft soil foundation. The detailed contents of paper as follows:(1) The problem of soil classification and engineering classification of Decayed Wood and Silt Mixed Soil are discussed. With method of borehole information, spore and pollen test and scanning electron microscope (SEM), cause of geology environment of Decayed Wood and Silt Mixed Soil is researched.(2) Undisturbed Decayed Wood and Silt Mixed Soil is obtained by dry ice freezing and bigbore sampling method. Furthermore, a large-diameter consolidometer is processed to ensure that the indoor test carries through successfully.(3) With a series of settlement characteristic test, the basic physical index, coefficient of consolidation, coefficient of secondary consolidation, coefficient of compression, compression index and recompression index are gained, which are compared with index of silt in Decayed Wood and Silt Mixed Soil layer.(4) Researching on the change law of basic indexed of Decayed Wood and Silt Mixed Soil under different surcharge conditions, A conclusion is put forward that surcharge has powerful effect on coefficient of secondary consolidation index of Decayed Wood and Silt Mixed Soil.(5) Based on actual measurement data, the settlement law of Decayed Wood and Silt Mixed Soil is analyzed, while the settlement mechanism is discussed. A conclusion is brought forward that the surcharge preloading with sand drains as foundation treatment is a successful method to dealing with the Decayed Wood and Silt Mixed Soil foundation.