Application Of Geocell Green Protection System In Subgrade Slope

Geocell is a kind of geosynthetics family.As a honeycomb three-dimensional network structure,it is fixed on the surface of the slope,and filled with vegetation soil,sand,and other materials.It constitutes a structural layer with certain lateral restrictions and stiffness,which provide the necessary environment for plant growth,forms a paving geocell vegetation slope protection,prevents soil erosion,and realizes slope ecological greening protection.Based on Jingxiong(Beijing-Xiong ’an New Area)highway subgrade slope in Hebei section of paving geocell slope protection project,this paper studies the types of Highway subgrade slope protection types,the tensile test characteristics of geocell,the protection mechanism and construction technology of geocell vegetation slope protection system,provides the basis and suggestions for the engineering application of geocell vegetation slope protection system.The main research contents are as following :(1)The basic principle,applicability,advantages,and disadvantages of commonly used highway slope protection types are compared and analyzed.It is considered that the comprehensive protection system combined with geosynthetics and vegetation protection is more in line with the needs of modern highway construction.In the early stage of protection,the advantages of geosynthetics are used to reinforce the slope surface,prevent slope erosion,and provide a favorable living environment for vegetation growth.In the later stage,the advantages of slope protection are combined with vegetation integrated into the surrounding ecosystem to form a good landscape effect;(2)The possible stress and corresponding failure modes of the whole cell-wall and junction under different laying modes in the construction of the geocell protection system is analyzed.Six types of tensile tests of the cell-wall and junction of HDPE welded geocell with holes are carried out to simulate the possible stress modes in the field.It is found that the tensile test results of the cell-wall are more likely to be inconsistent,which can be attributed to the inconsistency of the material itself.The tensile test results of the junction are uniaxial tensile strength > tensile strength >shear strength > peel strength,and the tensile strength of the junction uniaxial tensile strength test is far greater than the other three tests.A ductility coefficient is utilized to quantify all the tests of different loading types.The results show that the spalling and tensile failure at the junction is more likely to occur in the whole geocell protection system.In practical engineering construction,considering both strength and deformation,the construction method of vertical laying along the slope in the construction of geocell slope protection is more reliable,which is helpful to improve the service life of geocell in slope protection;(3)Aiming at the tensile test of welded junction in geocell,the influence of different distance between fixtures(10.5 mm,25 mm,50 mm,100 mm)on the test results was studied.The results show that the yield strength of uniaxial tensile strength test and shear strength test decreases with the increase of distance between fixtures,and the displacement required for peak value and final fracture increases.The peel strength test and tensile strength test of the junction have no effect on the test results with the increase of the distance between the fixtures;(4)The composition,construction process,and slope protection mechanism of geocell vegetation slope protection system are summarized and improved.Based on the limit equilibrium method,the corresponding mechanical model is established,and the calculation expression of slope stability is analyzed.Under the uniform action conditions,the two models are compared and deduced.It is found that the safety factor of geocell slope protection is significantly greater than that of non-geocell slope protection.It further proves the positive role of geocell in slope protection.