Laboratory Studies On The Causes Of Infected Gulf-phase Organic Sand And Engineering Properties

Hainan Island is in-depth development and construction of the international tourism island, for example, Wenchang satellite launching base in Sanya Begonia Bay coastal superior tourist holiday area and other plenty of engineering construction projects are being or will be carried out. As has merits of low-cost, high-quality, construction conveniency, environment-friendly, the soil cement mixing pile is widely used in various types of engineering practice. However, in the coastal region, because of alternate affects between the sea and the land, and the subtle geological conditions, ample organic-rich sediments have filtered into soil. This situation badly impacts the strength of soil cement mixing pile, and the effects of foundation treatment and waterproof have been largely reduced. This does not just increase the cost of construction of the project, and it may also lead to the extension of the construction projects, thereby affecting the region and even the provincial economic and social development.Steming from the existence of organic matter infected sand, using the mothed by scanning electron microscope and energy dispersive analysis device, this thesis brought forward a supposition of the origin of organic matter infected sand, then summed up the engineering properties of organic infected sand via conventional geotechnical experiments ent mixing pile process is also simulated in the laboratory. Finally, the optimum means of construct cement mixing pile in the sand of organic matter infection has been found out.The main findings of this paper are as follows:’First, the organic matter in the sand of organic matter infection is the result of following process:the organic matter invaded into the small opening of the sand particles, and adsorbed on porosity surfaces of sand particles, then underwent a series of physical and chemical reactions with mineral component of sand by the premotion of microorganisms. The poor mechanics behavior of soil cement mixing pile in the organic matter infection sand caused by the granules and forms of the organic matter;Second, the formation of organic matter infected sand is the role of organic matter particles rain and groundwater infiltration into the ground, and after a long period of time under the influence of alternating marine and terrestrial, and gradually adsorbed on the surface of the sand particles, and then invade the sand particles pores in the sand minerals, in the long years of complex physical, chemical and biological reactions, and ultimately formed; Third, it summarizes the engineering properties of the organic matter infected sand; Via plenty of experiments in the laboratory, the efficient method of pile construction in organic matter infected soil has been found out.