Due to the particularity of soil materials, the damage ratio is generally assumed from a macro perspective. The damage ratio factor used in this paper mainly considers the volumetric strain and shear strain of the soil, introducing Ev and Es in X, and assuming [3]X=1-e-(c0 caEv cbEs) (1) where: c0 Consider the influence factors of sampling disturbance; Ev volume strain, Ev = E1 E2 E3; Es shear strain, Es = 12 (E1-E2) 2 (E2-E3) 2 (E3-E1) 2; ca, cb parameters, through simulation The compression curve of undisturbed soil and remolded soil is determined.
Settlement calculation in the reinforced area The surface layer in most sections of the northern bank of the Shenzhen River is a newly backfilled plain fill. The bottom is a 620-m thick coastal zone, marine-continental sedimentary silt, silty silty clay, and sub-clay layers. The soil has pores. Larger than, high water content, high compressibility, low strength and bearing capacity. In order to ensure the bearing capacity of the foundation of the vertical retaining wall and the safety and stability of the river excavation, the technical plan for the reinforcement of the soft foundation of the bank slope by using plastic plate drainage and sand pile compression and drainage vacuum preloading is adopted. In the project, regardless of the type of machine and method used to set the plastic drainage board, the mechanical properties of the soil will be deteriorated, that is, the soil will be damaged to a certain extent.
For the calculation in this paper, take a test area as an example, and see the plane in the area. In the test area, CH1 900 was selected as the typical calculation section. Measured instruments such as diaphragm surface settlement plates and inclinometer tubes were set up on the section. The distance between plastic drainage plates is 1.2m, and the layout is square. When the soil mechanical properties index is taken into account, the damage of soil is taken into consideration, so that the calculation result is more in line with the actual situation.
The deterministic double-yield surface viscoelastic viscoplastic model of the calculated parameters contains 12 parameters of M, E0, Ge, Gp, E1, M1, M2, pr, h, m, a, and X. For the undisturbed soil, elastic Poisson is used. Ratio M = 0.3, except for X, M1, M2, pr, h, m, and a can be determined by ordinary triaxial tests [6], E0, Ge, Gp, E1 need to be determined by the stress triaxial test [5] .
The determination of X compares the compression curve of the undisturbed soil with the compression curve of the remolded soil as shown. Let the void ratio at the turning point when the two curves are substantially parallel be ea, and then assume that the damage ratio at this time is X=0.95, which can be obtained from equation (1): ca=ln20-c0(e0-ea)/(1 e0)- Cb(2) sets the X = 0.95 at the turning point of the stress-strain curve at the late stage of the stress-strain curve reduction in the unconfined test. Considering Ev = 0 at this time, cb = ln20-c01.5Eb can be obtained from equation (1). Eb is assumed here. =ea/(1 e0).
For the undisturbed soil taken from the project site, a large number of compression comparative tests of the original and remolded soils were carried out. The parameters of the test were obtained as follows: Density Q=1.591.78g/cm3, Moisture content w=43.2r.3 %, ca=2.03.6, cb=6.527.87.
The determination of viscous parameters is determined by an in-house stress triaxial test to determine the viscous parameters of the soil [5]. Three sets of triaxial rheological tests under different confining pressures were performed on the soil samples retrieved from the engineering site. The physical properties of the soil sample can be found. For R3 = 50, 100, 150 and 200kPa test under different confining pressure, the steps are roughly as follows: (a) sample consolidation, soil consolidation in the case of isotropic pressure, the time is generally about 12h; ( b) Read the volumetric strain and axial strain at the completion of the consolidation, and then apply the axial deviatoric stress (R1-R3) in stages. The classification is based on the stress level s. The first level is about s=10%, the second, Grades 3 and 4 are 30%, 50%, and 75%, respectively; (c) After incremental $ (R1-R3) is applied, the process of axial deformation and volumetric deformation with time is recorded until the deformation is stabilized (every 24 h axis The deformation is less than 0.005mm); (d) The next stage load is applied after the deformation is stabilized. This is repeated until the specimen is destroyed.
Conclusion a. In the calculation of soft soil foundation reinforcement in coastal areas, the rheology of soft soil should be considered. b. When plastic drainage boards are used to reinforce soft soil foundations, the installation of drainage boards has caused the soil to be damaged to a certain degree. When calculating the settlement, introducing the damage ratio factor can increase the calculation accuracy by about 10%.
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