| High liquid limit clay embankment slope is often reinforced by concrete gravity retaining wall.Although this method has good protection function,building concrete gravity retaining wall requires transporting stone and other building materials in different places,and can not effectively use the high liquid limit clay on site.The soil quality of K8+400～K9+100 section of Baixin Expressway in Hunan Province is high liquid limit clay,which has poor engineering properties and is often treated as abandoned side.Cement-based improved soil has good mechanical properties,and the improved soil gravity retaining wall can effectively replace the concrete gravity retaining wall to strengthen the embankment slope and improve the slope stability.If silica powder can be added to the cement-based improved soil to improve the mechanical properties of the cement improved soil,and the cement silica powder improved high liquid limit clay can be used to build the improved soil gravity retaining wall to strengthen the Baixin expressway embankment slope,it can reduce the stone transport in different places,so as to achieve the green construction purpose of saving construction cost and protecting the environment.Therefore,this paper comprehensively adopts theoretical research,laboratory tests,numerical simulation calculation and engineering practice and other research methods,focusing on the analysis of physical and mechanical properties of cement silica micro powder improved high liquid limit clay,analysis of microscopic mechanism of improved soil,numerical simulation calculation of improved soil gravity retaining wall to strengthen embankment slope,and practical application of improved soil gravity retaining wall to strengthen embankment slope,etc.The main achievements are as follows:(1)The basic physical and mechanical properties of the field soil samples were tested,and it was confirmed that the test soil samples were high liquid limit clay,with the engineering characteristics of extremely high fine particle content,high liquid limit and plastic index,and low compressive and shear strength.(2)Tests on mechanical properties of high liquid limit clay improved by cementsilica micro powder with different mix ratios were carried out,and the variation laws of strength parameters and stress-strain curves of improved soil with different mix ratios were verified.The results show that cement silica powder can effectively improve the mechanical properties of high liquid limit clay.When the content of 10%improver is 8%cement+2%silicon powder,the optimal mix ratio is 2.54MPa,the cohesion is 155.34kPa and the internal friction Angle is 42.80° during 7d curing.Compared with high liquid limit clay,the results were 151.49%,416.4%and 117.8%,respectively.(3)The micro test of cement-silica micro powder improving high liquid limit clay was carried out,and the mechanical property mechanism of cement-silica micro powder strengthening high liquid limit clay was revealed by analyzing the micro structure of the improved soil.The results show that the cement hydration reaction is the main reason for improving the mechanical properties of the improved soil,and the pozzolanic reaction and pore filling of the silica micro powder further improve the strength of the improved soil.The mechanism of the strength of 8%cement+2%silica micro powder improved soil is higher than that of 10%cement improved soil is explained.(4)Based on the strength reduction theory and the application of ABAQUS software,the numerical simulation calculation of the embankment slope reinforced by high liquid limit clay improved by cement silicon micro-powder was carried out.The calculation results show that the supporting effect and integrity of the embankment slope reinforced by high liquid limit clay modified by cement silicon micro powder are good,and the safety factor of the slope is increased.The maximum horizontal and vertical displacement of slope can be reduced in different degrees,and the critical sliding surface area can be increased to make the slope stable.(5)The engineering practice of improving high liquid limit clay with cement silicon micro powder to strengthen embankment slope has been carried out.Through the analysis of slope displacement monitoring results,it is found that the improved soil gravity retaining wall has obvious supporting effect on the embankment slope,and the overall stability of the slope is good after the completion of construction.The accuracy of numerical simulation results of embankment slope reinforced by improved soil gravity retaining wall is verified by engineering application. |
PDF Full Text Request