| With the proposal of the policy of building Guangdong,Hong Kong and Macao Bay area,Guangzhou,as the core city of Guangdong,Hong Kong and Macao Bay area,the development of infrastructure construction,rail transit,underground space and so on becomes more and more important.However,Guangzhou is located at the confluence of Xijiang River,Beijiang River and Dongjiang River,which belongs to the soft soil landform of the Pearl River delta formed in six stages of three regressions and three transgressions.The soft soil in the Pearl River Delta is characterized by complex composition,strong compressibility and low bearing capacity,so it is easy to cause foundation instability or settlement in the process of engineering construction and after the completion of buildings.In addition,as a super large city,Guangzhou has a rapid population growth and a shortage of land resources.The hydraulic fill land foundation project formed by mixing and absorbing the sand deposited in the river and the foundation clay will also become a development trend.Therefore,it is of great significance to study the influence of different sand content on the creep characteristics of soft soil in Guangzhou.In this paper,the influence of sand content on the creep characteristics of soft soil in Guangzhou area is analyzed from the macro level through one-dimensional consolidation creep test and direct shear creep test under different sand content and stress conditions,and the creep deformation mechanism is analyzed based on the creep deformation theory.The main research results are as follows:1 In this paper,one-dimensional consolidation creep tests of soft soils with different sand contents are carried out to analyze the creep deformation of soft soils under different vertical loads.The results show that with the increase of sand content,the consolidated creep deformation of soft soil decreases,and the creep deformation is less significant.The lower the sand content is,the more significant the increment of consolidation creep deformation of soft soil will be with the increase of consolidation pressure.The greater the consolidation pressure,the more significant the influence of sand content on the consolidation creep deformation of soft soil;2 In this paper,direct shear test and direct shear creep test of soft soil with different sand content are carried out to analyze the shear strength index and creep deformation of soft soil under different shear stress.The results show that the cohesion of soft soil decreases with the increase of sand content,and the internal friction Angle increases with the increase of sand content.With the increase of sand content,the shear creep deformation of soft soil decreases.The influence of sand content on shear creep deformation of soft soil is more significant with the increase of shear stress;3 Based on the consolidation creep test results,it is found that different consolidation pressure and different sand content will affect the division of primary and secondary consolidation stages.With the increase of consolidation pressure,the time of primary consolidation stage increases,and with the increase of sand content,the time of primary consolidation stage shortens,and different sample preparation methods will also affect the creep deformation;4 Based on the results of direct shear creep test,this paper studies the variation of average viscosity coefficient and creep threshold stress of soft soil with sand content.It is found that the average viscosity coefficient and creep threshold stress of soft soil increase with the increase of sand content;5 From the macroscopic qualitative point of view,this paper analyzes the creep deformation mechanism of soft soil with different sand content by using the test results of consolidation creep and direct shear creep and creep curves.It is found that the soft soil with different sand content shows the creep characteristics of attenuation creep,and the creep curve consists of accelerated creep stage,attenuation creep stage and later creep stable stage. |
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