| In this paper,weak expansive soil in Huainan City is studied,by using the method of experimental research,the comparative expansion characteristics test of weak expansive soil and sand-encased pile weak expansive soil,direct shear test of pile-soil contact surface,consolidated undrained triaxial test of sand-encased pile weak expansive soil composite,calculation formula of bearing capacity of composite foundation with wrapped granular material,and treatment of expansive soil slope by sand-pile-anti-slide pile carried out.The results show that:The expansion deformation of weak expansive soil and weak expansive soil with sand-encased piles has a strong functional relationship with water content,dry density and vertical load,and the weak expansive soil with sand-encased piles reduces the expansion of weak expansive soil to a certain extent under the same conditions.The larger the water content is,the more obvious the reduction effect of wrapped sand pile on the expansion and linear shrinkage of weak expansive soil is;The rate of expansion deformation can be described as three stages:rapid,slow and stable.Rapid expansion accounts for more than 80%of the total.The expansion and shrinkage of expansive soil of wrapped sand pile are inconsistent,and the expansion is far greater than the shrinkage.With the increase of water content,the shear strength on the interface between the wrapped material and the soil first increases and then decreases,reaching the peak value when the water content is 18%;With the increase of the overlying load,the shear strength between the wrapped material and the soil interface has been significantly improved.When the vertical load is large,the stress-strain curve is hardening.The shear stress of pile-soil interface accords with Mohr-Coulomb criterion;In a certain range(25kPa-300kPa),the shear stress on the interface is negatively correlated with dry density,but positively correlated under large load(400kPa).The wrapped sand pile has great cohesion due to the influence of wrapped materials;Compared with the weak expansive soil,the shear strength of the weak expansive soil composite with wrapped sand pile is significantly improved,and the strength curve shape changes from hardening to softening,and the strain corresponding to the peak strength decreases.Under lower confining pressure,the shear strength is greatly affected by the wrapping material.Through experimental analysis,the bearing capacity calculation formula of composite foundation wrapped with sand pile expansive soil is established,and the sand pile and anti-slide pile are mixed to jointly deal with expansive soil slope.It is hoped that this study can provide an idea for the construction of expansive soil composite foundation and expansive soil slope.Figure[66]Table[19]Reference[80]... |
