Study On The New Process Test Of Deep Soft Soil Without Sand Vacuum Preloading Method

Vacuum preloading is a common ground treatment process for coastal dredger fill soft soil.It is widely used in the port and waterway engineering field of China.However,with the increasing scarcity of sea sand resources,the lack of sand cushion materials has become a bottleneck restricting the development of the technology.So in recent years,the technology of vacuum preloading without sand cushion has appeared.But at present,the process has not been clearly defined in the national and industrial specifications.There are many problems in practical application,such as easy silting of plastic drain board,high efficiency and low energy consumption of vacuum pumping equipment,poor vacuum transfer efficiency of preloading drainage system and so on.In view of the above problems,this paper studies and formulates three optimization directions,forms a new technology of vacuum preloading method without sand for deep soft soil,and carries out field comparative tests in three test areas A,B and C.The test results show that:(1)The new type of plastic drainage board for silt prevention replaces the common plastic drainage board,which reduces the possibility of particle aggregation and silting around the drainage board.(2)The vacuum pumping equipment composed of water ring vacuum pump and water and gas separation tank replaces the traditional jet pump,which improves the vacuum pumping efficiency,reduces the power consumption,and is more convenient for maintenance and management.(3)The completely closed direct connection technology forms a new type of horizontal and vertical drainage system,which revolutionizes the connection between the traditional drainage board and the filter cloth,reduces the loss of vacuum during transmission,improves the vacuuming efficiency,and avoids the suction of the filter tube occurs at the same time.(4)Instead of full-size plastic drainage board,the narrowed plastic drainage board maximizes the performance of water permeability,reduces the consumption of drainage board materials,reduces the unit cost of the new process,and improves the economy of the new process.Compared with the traditional process,the new process is more reliable,convenient,efficient and energy-saving,and has obvious advantages in vacuum treatment effect and economy,which can be applied in similar projects.