Study On The Engineering Characteristics Of Weak Expansive Soil And Its Application In Artificial Hills

With the rapid development of urban and urbanization construction,the scale of engineering construction is constantly expanding,a large number of abandoned soils would be produced in the construction.It would cause a lot of problems,such as appropriation of cultivated land,transportation processes affect cleanliness and tidiness and secondary disasters caused by rainwater scouring.Thus,using abandoned soil to build man-made landscape hill is becoming more and more popular.However,there are some problems such as low mechanical strength of soft soil hill material,difficult coordination with surrounding buildings,expansive soil shrinks and expands sharply in water absorption,lack of design specifications and so on,which are easy to cause engineering accidents.In view of this,this paper reveals the mechanical characteristics of artificial hill packing through laboratory tests and mathematical models.A new artificial hills foundation treatment and a new method for calculating the hill overall stability are invented to increase hill stability.The results are shown as followed:(1)Laboratory tests have been carried out to determine the mechanical properties of man-made hill landfill.Its average density is 1.915 g/cm3.Its average specific gravity is 2.693,plastic index is 19.17,compression coefficient is 0.264 MPa-1,and compression modulus is 6.815 MPa.It belongs to medium compressive soil.The cohesion is 43.148 kPa and the angle of internal friction is 11.34 degrees.The cohesion and internal friction angle decrease with the increase of water content and increase with the increase of lime content.(2)Taking typical soil-Hefei weak expansive soil which has the characteristic of weak expansive soil as the study object,the engineering survey,topographic features,soil composition,mechanical indexes and special soil are analyzed to determine the bearing stratum of pile foundation.DC model and HSS model are selected and model parameters are determined.(3)Large geotechnical engineering finite element design and calculation software PLAXIS software is used to simulate the interaction of surrounding soil.HSS model is used to analyze the application effect of mountain landfills.(4)The artificial hill scheme and the integral stability calculation of hill have been carried out.Measures of increasing the board piles number to improve the stability of hill structure are put forward.