CN1609351A - Set-up method for generalized Bingham soft soil rheological deformation analogue body - Google Patents

Abstract

The generalized Bingham soft earth rheologic deformation model is for building structure deformation controlling design and relevant research. The model establishing process includes the following steps: a. inputting embankment design parameters; b. inputting composite foundation processing parameters; c. automatic grid division; e. inputting model parameters; f. embankment load increment; g. reclamation time increment; h. coupling plastomer with generalized Bingham body based on Bitot consolidation formula; i. determining unit stiffness matrix and establishing code and characteristic of each grid unit body; j. constituting overall rigidity matrix; k. finite element solving Bitot consolidation formula to find the solutions in the points within the researched space; l. judging whether to meet the boundary condition, and if no, returning to i.; m. calculating the node force, displacement and hole pressure and returning results to f. and g.; and n. outputting results to end.

Description

The method for building up of broad sense Bingham soft soil rheological deformation simulative body

Technical field

The present invention is a kind of method that is used for building structure control deformation design and correlative study.Especially a kind of method for building up that directly applies to the broad sense Bingham soft soil rheological deformation simulative body of field of civil engineering.

Background technology

China was carrying out large-scale infrastructure always in recent years; construction as key projects such as speedway, railways; in speedway, railway construction process; pass through soft clay area inevitably, occur a lot of engineering problems at soft clay area building highway, railway through regular meeting, the subgrade settlement distortion is excessive; influence is normal current: occur jumping car when end of the bridge, the driving of box culvert connecting portion; there is flood control flood fighting hidden danger in culvert because sedimentation influences water system Channel Group.This is not enough mainly due to deformation characteristic of weak soil understanding, perhaps can not with one accurately distorted pattern the rheology deformation characteristic of weak soil is described.Though the research of this respect has obtained many achievements, the understanding rheological behavior of soft soil, the stress relaxation phenomenon of soil can only be described as the Maxwell model, Kelvin model can only be described the elastic aftereffect of soil and answer character, that revises examines the ultimate strength that horse traction-yellow model and Bingham can only be described soil, process and phenomenon that these several phenomenons all can not the accurate description subgrade deformation be destroyed.Because it is process by being gradient to sudden change that the deformation failure of roadbed begins, beginning gradual change distortion can be approximately elastoplasticity, and sudden change is a limit breakoff phenomenon at last.

Summary of the invention

Technical problem: the present invention seeks to propose a kind of method for building up of broad sense Bingham soft soil rheological deformation simulative body, the rheology deformation characteristic of accurate description weak soil is so that realize the controlled deformation design of speedway, railway.

Technical scheme: China has speedway and the railway much built (as to hold together extra large railway Lianyun Harbour section year annual overhaul in the operation process, roadbed accumulative total sedimentation maximum is near 2 meters), what have deformation failure (as connecting Xu's speedway second phase Lianyun Harbour section) just occurs in the construction process, influence the normal operation of engineering, cause a large amount of economic losses.Characteristic phenomenon for the sedimentation and deformation of accurate description roadbed, for engineering design provides reliable theoretical foundation, the inventor carries out field investigation, laboratory test and calculating analysis and summary engineering characteristics phenomenon, it is process by being gradient to sudden change that the sedimentation and deformation of roadbed begins, and then a kind of broad sense Bingham soft soil rheological model is proposed, the characteristic phenomenon of soft soil rheological distortion can be described exactly.

This model is constituted by two parts, and a part is an elasticoplastic body, describes the elastic-plastic deformation of embankment gradual change distortion; Another part is a generalized Bingham body, describes the rheology deformation failure feature of embankment.By Biot consolidation equation these two unit pieces are carried out linear combination, and, set up relevant numerical algorithm, the feature of accurate description Embankment Subsidence distortion by testing the parameter of determining the correlation unit body.

The analog computation of this model, at first to research ground and embankment and relevant controlling parameters, the height, embankment that comprises embankment be the soil layer lift height parameter of width, average unit weight parameter and ground up and down, research object is carried out mesh generation, again by ordinary triaxial test and K ₀Model parameter is obtained in the test of concretion method triaxial rheology, and these parameters are mainly described the elastic-plastic deformation of the soil body and the test parameters of rheology deformation behaviour; The simulation embankment fills process setting load increment and incremental time, Biot consolidation equation is coupled elasticoplastic body and broad sense Bingham model, the stiffness matrix of determining unit body and global stiffness matrix, utilize finite element to carry out numerical solution, numerical computations obtains stress, displacement and the pore water pressure value of each node, finally obtains the sedimentation and deformation of roadbed.

The method for building up of this model is:

A, input embankment design parameters, i.e. levee crown, bottom width, dike height, average unit weight;

B, input composite foundation processing parameter are promptly handled the degree of depth, replacement ratio, soil layer parameter;

C, grid automatic division;

E, input model parameter are promptly imported the elastoplasticity cell parameters of ordinary triaxial test, K ₀The rheological unit parameter of concretion method triaxial rheology test; K ₀Concretion method is a kind of soil test method of setting, and the lateral pressure that the soil sample of requirement test is born and the ratio of vertical pressure equal constant K ₀Carry out deformation test:

F, embankment load increment, i.e. certain one deck embankment filled height, being equivalent to active force is the size increment of load;

G, fill incremental time, be certain one deck embankment and fill the time, be equivalent to the space increment of the time of filling continuously;

H, the distortion of setting up the Biot consolidation equation statement soil body are coupled plastic body and generalized Bingham body, are about to the elasticoplastic body and Bingham limit destruction body and get in touch by Biot consolidation equation foundation:

I, determining unit stability matrix are set up coding to each grid cell body, as stressed size, and the displacement deformation of generation:

J, formation global stiffness matrix are about to all grid cell bodies according to its coding and ordering, describe the stressed and displacement deformation of whole research object:

K, finite element solving Biot consolidation equation are being studied separating on the each point of space (each point position, space is determined by step c grid automatic division), and this comprises stressed size and distortion size on grid cell and the grid node:

L, fringe conditions satisfy not, if do not satisfy fringe conditions, then return step I, the determining unit stability matrix; If satisfy fringe conditions, then carry out following step m,

Press in m, calculating joint forces, displacement, hole, simultaneously result of calculation is back to step f and step g and circulates;

N, output result of calculation finish.

Beneficial effect: based on this broad sense Bingham soft soil rheological model, the soft soil roadbed deformation behaviour of accurate description, for determining that the method that reasonable reinforced soft soil ground is handled provides theoretical foundation, to realize the controlled deformation design, guarantee speedway and railway security operation, reduce the economic loss that causes because of sedimentation and deformation is out of control simultaneously, save a large amount of maintenance costs, have tangible economic benefit.

Description of drawings

Fig. 1 is a broad sense Bingham soft soil rheological deformation simulative method schematic diagram.

Fig. 2 is the calculated examples schematic diagram.

Fig. 3 is the method for building up schematic diagram of broad sense Bingham soft soil rheological deformation simulative body.

The specific embodiment

The method for building up of broad sense Bingham soft soil rheological deformation simulative of the present invention is that the speedway K20+395 place of Four-Lane Road is an example explanation to connect Xu's speedway Lianyun Harbour section, the high 5m of embankment, and embankment top width 28m, bottom width 43m, the average unit weight of embankment is generally got 20kN/m ³Soft foundation is comparatively single, and also more single evenly the treated length of agitation pile is 12.5m to soil layer below the weak soil thickness 12m, weak soil layer, and pile spacing is 1.2m, and replacement ratio is 0.157.

A, input embankment design parameters, i.e. levee crown, bottom width, dike height, average unit weight; Concrete numerical value is respectively 28,43,5 and 20;

B, input composite foundation processing parameter are promptly handled the degree of depth, replacement ratio, soil layer parameter; Concrete numerical value is respectively 12.5,0.157,4;

C, grid automatic division;

E, input model parameter are promptly imported the elastoplasticity cell parameters of ordinary triaxial test, K ₀The rheological unit parameter of concretion method triaxial rheology test; K ₀Concretion method is a kind of soil test method of setting, and the lateral pressure that the soil sample of requirement test is born and the ratio of vertical pressure equal constant K ₀Carry out deformation test; Get K ₀=0.65 (test obtains), the viscous parameter η=3.5*10 of rheology ^-5(min ^-1), all the other some parameters are the test statistics parameter;

F, embankment load increment, i.e. certain one deck embankment filled height, being equivalent to active force is the size increment of load; The high 5m of embankment approximate be divided into four times and fill, and load increment is 25kPa;

G, fill incremental time, be certain one deck embankment and fill the time, be equivalent to the space increment of the time of filling continuously; The building time of speedway was generally 3～4 years, and in desirable 20～40 days usually time interval of calculating, it is 20 days that example is got the time interval;

H, Biot consolidation equation are coupled plastic body and generalized Bingham body, are about to the elasticoplastic body and Bingham limit destruction body and get in touch by Biot consolidation equation foundation;

I, determining unit stability matrix are set up coding and feature to each grid cell body, as stressed size, and the displacement deformation of generation;

J, formation global stiffness matrix are about to all grid cell bodies according to its coding and feature ordering, describe the stressed and displacement deformation of whole research object;

K, finite element solving Biot consolidation equation separating on each grid cell and grid node, this comprises stressed size and distortion size on grid cell and the grid node;

L, fringe conditions satisfy not, if do not satisfy fringe conditions, then return step I, the determining unit stability matrix; If satisfy fringe conditions, then carry out following step m,

Press in m, calculating joint forces, displacement, hole, simultaneously result of calculation is back to step f and step g and circulates;

N, output result of calculation finish.Result of calculation is seen accompanying drawing 2.

Consolidation deformation characteristic at Lianyun Harbour, Jiangsu marine soft soil, rheological behavior, set up a kind of broad sense Bingham soft soil rheological body, and soil body elastic-plastic deformation body and the broad sense Bingham limit are destroyed body organically combine, the software for calculation that establishment is relevant carries out settlement calculation, the elastoviscoplasticity model of considering rheology calculates the settling amount of settling amount and actual measurement relatively near (error is less than 10%), the settling amount precision of calculating than the elastic-plastic deformation body has improved more than 40%, successfully in the design of the second stage of the project of Xu of the company of being applied to speedway Lianyun Harbour section, again this achievement in research is promoted the use of Fen simultaneously and irritate speedway, connect in the design of salt speedway.

Claims (1)

1, a kind of method for building up of broad sense Bingham soft soil rheological deformation simulative is characterized in that method for building up is as follows:

A, input embankment design parameters, i.e. levee crown, bottom width, dike height, average unit weight;

B, input composite foundation processing parameter are promptly handled the degree of depth, replacement ratio, soil layer parameter;

C, grid automatic division;

E, input model parameter are promptly imported the elastoplasticity cell parameters of ordinary triaxial test, K ₀The rheological unit parameter of concretion method triaxial rheology test;

F, embankment load increment, i.e. certain one deck embankment filled height, being equivalent to active force is the size increment of load;

G, fill incremental time, be certain one deck embankment and fill the time, be equivalent to the space increment of the time of filling continuously;

H, Biot consolidation equation are coupled plastic body and generalized Bingham body, are about to the elasticoplastic body and Bingham limit destruction body and get in touch by Biot consolidation equation foundation;

I, determining unit stability matrix are set up coding and feature to each grid cell body, as stressed size, and the displacement deformation of generation;

J, formation global stiffness matrix are about to all grid cell bodies according to its coding and ordering, describe the stressed and displacement deformation of whole research object;

K, finite element solving Biot consolidation equation separating on the each point of research space, this comprises stressed size and distortion size on grid cell and the grid node;

L, fringe conditions satisfy not, if do not satisfy fringe conditions, then return step I, the determining unit stability matrix; If satisfy fringe conditions, then carry out following step m,

Press in m, calculating joint forces, displacement, hole, simultaneously result of calculation is back to step f and step g and circulates:

N, output result of calculation finish.