CN107958113B - Numerical analysis method for stability of tower foundation on unsaturated expansive soil foundation - Google Patents
Numerical analysis method for stability of tower foundation on unsaturated expansive soil foundation Download PDFInfo
- Publication number
- CN107958113B CN107958113B CN201711185166.5A CN201711185166A CN107958113B CN 107958113 B CN107958113 B CN 107958113B CN 201711185166 A CN201711185166 A CN 201711185166A CN 107958113 B CN107958113 B CN 107958113B
- Authority
- CN
- China
- Prior art keywords
- expansive soil
- unsaturated expansive
- model
- foundation model
- foundation
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 239000002689 soil Substances 0.000 title claims abstract description 275
- 238000004458 analytical method Methods 0.000 title claims abstract description 71
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 86
- 230000008859 change Effects 0.000 claims abstract description 40
- 238000006073 displacement reaction Methods 0.000 claims abstract description 33
- 238000000034 method Methods 0.000 claims abstract description 33
- 239000000463 material Substances 0.000 claims abstract description 31
- 230000005484 gravity Effects 0.000 claims abstract description 14
- 238000009826 distribution Methods 0.000 claims description 44
- 238000004364 calculation method Methods 0.000 claims description 38
- 238000012360 testing method Methods 0.000 claims description 34
- 230000008602 contraction Effects 0.000 claims description 15
- 230000003068 static effect Effects 0.000 claims description 12
- 230000000694 effects Effects 0.000 claims description 6
- 230000008569 process Effects 0.000 claims description 6
- 230000009467 reduction Effects 0.000 claims description 6
- 230000006835 compression Effects 0.000 claims description 3
- 238000007906 compression Methods 0.000 claims description 3
- 239000008239 natural water Substances 0.000 claims description 3
- 238000003825 pressing Methods 0.000 claims description 3
- 230000000452 restraining effect Effects 0.000 claims description 3
- 230000005540 biological transmission Effects 0.000 abstract description 12
- 238000010219 correlation analysis Methods 0.000 abstract description 2
- 238000010586 diagram Methods 0.000 description 8
- 238000013461 design Methods 0.000 description 7
- 238000005457 optimization Methods 0.000 description 5
- 230000009471 action Effects 0.000 description 4
- 230000001595 contractor effect Effects 0.000 description 4
- 238000012546 transfer Methods 0.000 description 4
- 238000010521 absorption reaction Methods 0.000 description 3
- 238000011161 development Methods 0.000 description 3
- 229910052500 inorganic mineral Inorganic materials 0.000 description 3
- 239000011707 mineral Substances 0.000 description 3
- 238000010008 shearing Methods 0.000 description 3
- 230000008961 swelling Effects 0.000 description 3
- 239000002131 composite material Substances 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 230000006378 damage Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 238000007596 consolidation process Methods 0.000 description 1
- 230000001808 coupling effect Effects 0.000 description 1
- GUJOJGAPFQRJSV-UHFFFAOYSA-N dialuminum;dioxosilane;oxygen(2-);hydrate Chemical compound O.[O-2].[O-2].[O-2].[Al+3].[Al+3].O=[Si]=O.O=[Si]=O.O=[Si]=O.O=[Si]=O GUJOJGAPFQRJSV-UHFFFAOYSA-N 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 229910052900 illite Inorganic materials 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000012821 model calculation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052901 montmorillonite Inorganic materials 0.000 description 1
- VGIBGUSAECPPNB-UHFFFAOYSA-L nonaaluminum;magnesium;tripotassium;1,3-dioxido-2,4,5-trioxa-1,3-disilabicyclo[1.1.1]pentane;iron(2+);oxygen(2-);fluoride;hydroxide Chemical compound [OH-].[O-2].[O-2].[O-2].[O-2].[O-2].[F-].[Mg+2].[Al+3].[Al+3].[Al+3].[Al+3].[Al+3].[Al+3].[Al+3].[Al+3].[Al+3].[K+].[K+].[K+].[Fe+2].O1[Si]2([O-])O[Si]1([O-])O2.O1[Si]2([O-])O[Si]1([O-])O2.O1[Si]2([O-])O[Si]1([O-])O2.O1[Si]2([O-])O[Si]1([O-])O2.O1[Si]2([O-])O[Si]1([O-])O2.O1[Si]2([O-])O[Si]1([O-])O2.O1[Si]2([O-])O[Si]1([O-])O2 VGIBGUSAECPPNB-UHFFFAOYSA-L 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/10—Geometric CAD
- G06F30/13—Architectural design, e.g. computer-aided architectural design [CAAD] related to design of buildings, bridges, landscapes, production plants or roads
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/20—Design optimisation, verification or simulation
- G06F30/23—Design optimisation, verification or simulation using finite element methods [FEM] or finite difference methods [FDM]
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
- G06F2119/06—Power analysis or power optimisation
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Geometry (AREA)
- Theoretical Computer Science (AREA)
- Computer Hardware Design (AREA)
- General Physics & Mathematics (AREA)
- Evolutionary Computation (AREA)
- General Engineering & Computer Science (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Computational Mathematics (AREA)
- Mathematical Analysis (AREA)
- Mathematical Optimization (AREA)
- Pure & Applied Mathematics (AREA)
- Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
The invention discloses a numerical analysis method for stability of a tower foundation on an unsaturated expansive soil foundation, which comprises the following steps of firstly, establishing a tower foundation model and an unsaturated expansive soil foundation model; then, corresponding material attributes are respectively given to the tower foundation model and the unsaturated expansive soil foundation model; then, establishing a correlation analysis step, carrying out grid division on the pole tower foundation model and the unsaturated expansive soil foundation model, setting boundary conditions for restricting the displacement of the bottom and the periphery of the unsaturated expansive soil foundation model, and applying a gravity load and a corresponding upper load of the pole tower foundation model; and finally, submitting the operation and analyzing the operation result. The method simply and effectively solves the problems of deformation and stability of the tower foundation of the power transmission line caused by the change of the water content in the unsaturated expansive soil foundation, can obtain the bearing capacity of the unsaturated expansive soil foundation with the changed water content, and provides a numerical analysis method for determining the stability of the tower foundation on the unsaturated expansive soil foundation.
Description
Technical Field
The invention belongs to the technical field of engineering application and computational soil mechanics, and particularly relates to a numerical analysis method for stability of a tower foundation on an unsaturated expansive soil foundation.
Background
The expansive soil is a high-plasticity clay which is composed of strong hydrophilic minerals (montmorillonite and illite) and has the characteristics of water absorption expansion and water loss contraction. The waterproof and waterproof composite material is extremely sensitive to environmental and climatic conditions, and the strength is obviously reduced after the waterproof and waterproof composite material is soaked, so that huge potential safety hazards are caused to the building and the structure on the expansive soil foundation. The expansive soil is distributed in various countries all over the world, and the expansive soil in China is widely distributed in regions, from Henan, Hebei to Guangxi, Yunnan and the like in the southwest. The areas mostly belong to semi-humid and semi-arid climatic regions and are characterized in that the alternation of the dry and the wet is clear. The expansive soil in engineering has the characteristics of non-saturation, super-consolidation, crack development and the like. Under such climatic conditions, the building structure sitting on the expansive soil foundation is susceptible to the expansive and contractive characteristics of the expansive soil, particularly the tower foundation of the power transmission line tower with low acting force on the upper part. However, the relevant building technical specifications of the building on the expansive soil foundation are mostly based on the conventional soil body, and the building technical specifications specially aiming at the expansive soil are not provided for the reference of the construction unit, so that the engineering project on the expansive soil foundation is often caused to have serious engineering problems, which not only causes great economic loss, but also causes serious influence on the healthy development of the society, and causes bad social public opinion. In particular, once a long-distance transmission line tower located on an expansive soil foundation is inclined and damaged due to instability, the power supply in a certain area is interrupted, the life and industrial production of residents are seriously influenced, and even social safety problems can be caused.
Numerous scientific studies indicate that the main reason causing the safe operation of buildings or structures on the expansive soil foundation is rainfall, namely, the distribution of the water content in the expansive soil foundation is changed due to rainfall or extreme climatic conditions, and the expansive soil is extremely sensitive to water and has the characteristics of extremely strong reduction of water absorption expansion strength and improvement of water loss contraction strength. At present, the most effective means for researching the structure on the expansive soil foundation is a field model test or an indoor model test, but the method has long period, wastes time and labor, and costs relatively high economic cost, so that the method is inconvenient for the actual and wide application of the engineering. With the development of scientific technology, analytical methods based on computer numerical computation are playing more and more important roles in engineering analysis and application. Moreover, based on a numerical calculation method, a stress field, a deformation field, a plastic region and the like in the soil body can be effectively obtained, and a stress concentration region in the soil body and the foundation can be more intuitively obtained relative to a model test, so that a good basis is provided for engineering design and optimization.
The analysis method based on the finite element temperature field has obvious similar effect with the swelling and shrinking effect of the expansive soil caused by the change of the water content. Firstly, the general material has the characteristics of volume expansion and strength reduction when the temperature is increased and volume contraction and strength improvement when the temperature is reduced, and the characteristics have strong similarity with the expansion and contraction effect of the expansive soil; secondly, when the object is acted by a heat source, a temperature change field controlled by a heat conduction equation is formed in the object and has a thermal coupling effect, and when the moisture content in the expansive soil is changed, a humidity field controlled by a moisture diffusion equation is formed, and a related scholars already derives a moisture stress balance differential equation of water-soil coupling under the condition of an isotropic linear expansion hypothesis, wherein the differential equation is very similar to a thermal coupling equation, so that a foundation is laid for simulating the humidity field by using the temperature field.
The patent with the publication number of CN 103967037B discloses an optimization design method of a tower rigid foundation, which is characterized in that on the basis of the mechanical property of mineral admixture concrete with a new formula, the stress distribution of the tower foundation and the surrounding soil body is calculated according to the existing finite element analysis method; by adopting the mineral admixture concrete mechanical parameters and the optimization design method for the power transmission line tower foundation, the checking calculation of the shearing resistance and the bearing capacity of the soil and the checking calculation of the shearing resistance and the bearing capacity of the foundation are carried out under the working condition of the action of the pull-out force; checking calculation of tensile bearing capacity and shearing resistance of the foundation under the working condition of lower pressure; and determining the optimal rigidity angle of the foundation under the condition of minimum consumption of the foundation concrete. The method can comprehensively consider the safety of the foundation under multiple working conditions, provides a simple and feasible optimization design method of the tower rigid foundation, and saves the consumption of tower foundation concrete by optimizing the foundation rigid angle. However, the method is not suitable for the calculation and analysis of the deformation of the transmission line tower foundation on the expansive soil foundation and the bearing capacity of the foundation.
The invention patent with the patent application publication number of CN107247857A discloses a method for analyzing the bearing capacity of a deflection pipe pile, which comprises the following steps: s1, dividing the deflection pipe pile into a plurality of deflection pipe pile units; s2, constructing a pile side load transfer function: s3, constructing a pile end load transfer function: s4, combining the pile side load transfer function and the pile end load transfer function to establish a mechanical model of the inclined tubular pile, calculating the internal force and displacement of each inclined tubular pile unit node and the side resistance and end resistance of the inclined tubular pile, and further obtaining the bearing capacity analysis result of the inclined tubular pile. The invention realizes the bearing capacity analysis of the inclined tubular pile and solves the problem that the bearing capacity of the inclined tubular pile cannot be analyzed theoretically in the traditional theory. However, the method is not suitable for calculating and analyzing the deformation of the transmission line tower foundation on the expansive soil foundation and the bearing capacity of the foundation.
In conclusion, the temperature field in the finite element software can be used for simulating the redistribution process of the humidity field in the soil body caused by the change of the water content, and the deformation of the power transmission line tower foundation on the expansive soil foundation and the change condition of the bearing capacity of the foundation caused by the redistribution process, so that an important reference basis is provided for engineering analysis, design and application.
Disclosure of Invention
In view of the above, the present invention provides a numerical analysis method for stability of a tower foundation on an unsaturated expansive soil foundation, which solves the problems of deformation and stability of a tower foundation of a power transmission line caused by a change in water content in the unsaturated expansive soil foundation, obtains bearing capacity of the unsaturated expansive soil foundation after the change in water content, and provides a numerical analysis method for determining stability of the tower foundation on the unsaturated expansive soil foundation.
In order to achieve the purpose, the invention adopts the following technical scheme:
a numerical analysis method for stability of a tower foundation on an unsaturated expansive soil foundation mainly comprises the following steps:
a. and (3) analyzing the ground stress balance: the device is used for eliminating the deformation of the unsaturated expansive soil foundation model caused by gravity;
b. a first static load analysis step: the method is used for analyzing the deformation condition of the tower foundation model under the normal operation load condition of the unsaturated expansive soil foundation model;
c. and (3) expansion calculation analysis step: the distribution condition of the water content in the unsaturated expansive soil foundation under the actual engineering condition is equivalently simulated by predefining the temperature field in the unsaturated expansive soil foundation model in ABAQUS, and the change process of the water content of the unsaturated expansive soil foundation model within the depth range influenced by the earth surface soil atmosphere is simulated by changing the distribution condition of the temperature field, so that the expansion and contraction deformation of the unsaturated expansive soil foundation and the change condition of the bearing capacity characteristic thereof caused by the change of the water content are calculated;
d. and a second static force calculation analysis step: applying a load to the tower foundation model for calculating the foundation bearing capacity of the unsaturated expansive soil foundation model after the water content is redistributed;
and 5, submitting operation and analyzing an operation result.
Preferably, the step 2 specifically includes the following steps:
s1, performing a basic physical mechanical test on the unsaturated expansive soil to obtain related physical parameters of the unsaturated expansive soil foundation under different initial water content conditions;
s2, determining the density, the elastic modulus and the Poisson ratio of the tower foundation model material according to the actual engineering condition;
s3, establishing corresponding material models for the tower foundation model and the unsaturated expansive soil foundation model respectively, wherein the tower foundation model selects an ideal elastic model, the unsaturated expansive soil foundation model selects an elastic-plastic molar-coulomb model, and corresponding material attributes are input respectively.
Preferably, in the step S1, the basic physical mechanical tests performed on the unsaturated expansive soil include a soil density test, a water content test, a liquid-plastic limit test, a compressibility test, an expansibility test and a triaxial test.
Preferably, in the step S1, the basic physical mechanical test is performed on the unsaturated expansive soil to obtain the relevant physical parameters of the unsaturated expansive soil foundation under the conditions of different initial water contents, including cohesion, internal friction angle, soil density, natural water content, liquid-plastic limit parameter, expansion characteristic parameter and compression characteristic parameter.
Preferably, the step 4 specifically includes the following steps:
(1) selecting a proper grid size, setting the type of grid unit as a three-dimensional eight-node one-time integral entity reduction integral unit C3D8R, and carrying out grid division on the unsaturated expansive soil foundation model and the tower foundation model;
(2) setting boundary conditions of the unsaturated expansive soil foundation model: constraining the displacement of the unsaturated expansive soil foundation model in three directions at the bottom and the horizontal displacement corresponding to four surfaces at the periphery;
(3) applying gravity load to the unsaturated expansive soil foundation model in the ground stress balance analysis step, and ensuring that the gravity load is continuously applied in the subsequent analysis step;
(4) applying an upper load comprising a downward pressing load, an upward pulling load and a combined load to the pole tower foundation model in the static load analysis step I, wherein the upper load is determined by actual engineering conditions and is ensured to continue to the expansion calculation analysis step;
(5) applying a predefined temperature field to the unsaturated expansive soil foundation model from the initial analysis step to equivalently simulate the distribution condition of the water content in the unsaturated expansive soil foundation under the actual engineering condition, wherein the predefined temperature field is determined according to the distribution condition of the water content in the unsaturated expansive soil foundation at the actual engineering location, and the predefined temperature field is ensured to be kept unchanged before the expansion calculation analysis step;
(6) changing the distribution condition of the water content in the unsaturated expansive soil foundation within the depth range of the atmospheric influence of the earth surface soil body in the expansion calculation analysis step, and calculating the expansion and contraction deformation of the unsaturated expansive soil foundation model caused by the change of the water content of the unsaturated expansive soil foundation so as to obtain the expansion and contraction deformation of the tower foundation model and the stress distribution condition in the unsaturated expansive soil foundation model generated thereby, so that the displacement condition of the tower foundation model generated by the water content distribution change in the unsaturated expansive soil foundation model can be obtained;
(7) changing the load value of the upper part of the tower foundation model in the static calculation and analysis step two, and calculating the bearing capacity of the unsaturated expansive soil foundation model under the new humidity field distribution condition, so that the change condition of the bearing capacity of the unsaturated expansive soil foundation model caused by the change of the water content can be obtained;
preferably, in the step 5, the analysis of the operation result includes distribution of a humidity field, stress, strain and plastic region in the unsaturated expansive soil foundation model, and deformation characteristics generated by bearing capacity of the tower foundation model and a swelling and shrinking effect of unsaturated expansive soil.
Preferably, in order to eliminate the influence of the boundary effect on the model calculation result as much as possible, the size of the unsaturated expansive soil foundation model is 3.0-5.0 times that of the tower foundation model.
Preferably, the atmospheric influence depth range of the earth surface soil body is 3.0-5.0 m.
The invention has the beneficial effects that:
the invention provides a numerical analysis method for the stability of a tower foundation on an unsaturated expansive soil foundation, aiming at the problem that the stability of the tower foundation is caused by the deformation of a tower foundation of a power transmission line caused by the change of the water content in the unsaturated expansive soil foundation at present, and no simple and effective method for analyzing the bearing capacity of the unsaturated expansive soil foundation exists at present, and firstly, a tower foundation model and an unsaturated expansive soil foundation model are established; then, respectively establishing material attributes of a tower foundation model and an unsaturated expansive soil foundation model; then, establishing a correlation analysis step, carrying out grid division on the pole tower foundation model and the unsaturated expansive soil foundation model, setting boundary conditions for restricting the displacement of the bottom and the periphery of the unsaturated expansive soil foundation model, and applying a gravity load and a corresponding upper load of the pole tower foundation model; and finally, submitting the operation and analyzing the operation result.
By the calculation method, the displacement deformation condition of the tower foundation on the expansive soil foundation caused by the change of the water content can be simply and effectively obtained, the upper structure of the tower foundation can be effectively analyzed, the tower foundation can not be inclined or even toppled and damaged due to the expansion and contraction deformation of the expansive soil, the structure and the foundation soil body internal force distribution diagram caused by the expansion and contraction deformation of the expansive soil can be obtained, and the corresponding optimization design can be carried out on the stress concentration area, so that the construction cost is saved, and the engineering safety is improved.
In addition, the bearing capacity of the expansive soil foundation after the water content is changed can be simply and efficiently obtained through numerical calculation, the foundation instability damage caused by insufficient strength due to the strength change (mainly strength reduction after water absorption) of expansive soil on the tower foundation can be avoided, and compared with a complex and time-consuming huge model test, the method has great economic and efficiency advantages.
The method simply and effectively solves the problems of deformation and stability of the tower foundation of the power transmission line caused by the change of the water content in the unsaturated expansive soil foundation, obtains the bearing capacity of the unsaturated expansive soil foundation after the change of the water content, and ensures that the tower foundation on the unsaturated expansive soil foundation cannot be unstably damaged due to the fact that the strength does not meet the requirement.
Drawings
FIG. 1 is a flow chart of a method for analyzing the stability of a tower foundation on an unsaturated expansive soil foundation according to the present invention;
FIG. 2 is a diagram of the size and grid division of a tower foundation model in an embodiment of the invention;
FIG. 3 is a diagram illustrating the dimensions and grid divisions of a model of an unsaturated expansive soil foundation in accordance with an embodiment of the present invention;
FIG. 4 is a stress cloud of the unsaturated expansive soil foundation model in an embodiment of the present invention;
FIG. 5 is a displacement cloud of the unsaturated expansive soil foundation model in an embodiment of the present invention;
FIG. 6 is a schematic diagram illustrating the distribution of the moisture field in the unsaturated expansive soil foundation model after the step of expansion calculation and analysis in the embodiment of the present invention;
FIG. 7 is a cloud of stress distributions in the unsaturated expansive soil foundation model after the step of expansive calculation and analysis in accordance with an embodiment of the present invention;
FIG. 8 is a cloud of displacement distributions in the unsaturated expansive soil foundation model after the step of expansive calculation and analysis in accordance with an embodiment of the present invention;
FIG. 9 is a cloud of equivalent plastic strains in the unsaturated expansive soil foundation model after the step of expansive calculation and analysis in accordance with an embodiment of the present invention;
FIG. 10 is a graph showing the displacement time of the top of the tower foundation and the earth surface of the unsaturated expansive soil foundation during the expansion calculation and analysis step in the embodiment of the present invention;
FIG. 11 is a cloud of stress distributions in the unsaturated expansive soil foundation model after redistribution of water content in an embodiment of the present invention;
FIG. 12 is a cloud of displacement distributions in the unsaturated expansive soil foundation model after redistribution of water content in an embodiment of the present invention;
FIG. 13 is a cloud of equivalent plastic strains in a model of unsaturated expansive soil foundations after redistribution of water content in accordance with an embodiment of the present invention;
FIG. 14 is a load-displacement curve of the unsaturated expansive soil foundation model reaching the ultimate bearing capacity after the water content is redistributed in the embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to fig. 1 to 14 of the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention, are within the scope of the invention.
In the embodiment, as shown in fig. 1, a flow chart of a method for analyzing numerical values of stability of a tower foundation on an unsaturated expansive soil foundation of the invention is shown, and a plate-type foundation of a linear tower of a certain power transmission line is taken as an example below, and displacement deformation conditions and subsequent foundation bearing capacity caused by changes of water content of a foundation soil body under the action of an upper load are analyzed, and the method specifically comprises the following steps:
s1, carrying out basic physical mechanical tests including a soil body density test, a water content test, a liquid-plastic limit test, a compressibility test, an expansibility test and a triaxial test on unsaturated expansive soil to obtain relevant physical parameters of the unsaturated expansive soil foundation under different initial water content conditions, wherein the relevant physical parameters include cohesion, internal friction angle, soil body density, natural water content, liquid-plastic limit parameters, expansion characteristic parameters and compression characteristic parameters;
according to the results of the physical and mechanical tests of the foundation, the material properties of the obtained unsaturated expansive soil foundation model are shown in the following table 1;
s2, determining the density, the elastic modulus and the Poisson ratio of the tower foundation model material according to the actual engineering condition, wherein the material properties of the concrete tower foundation model are shown in the following table 2;
in addition, according to the indoor no-load expansion rate test performed on the unsaturated expansive soil, the relation between the expansion rate and the initial water content of the unsaturated expansive soil is fitted as follows:
thereby obtaining different initial water content omega1And final water content omega2Corresponding expansion ratio deltaps1And deltaps2According to the theory related to the equivalent humidity field of the temperature field, the linear expansion coefficient caused by the change of the humidity field is as follows:
in the formula: ν is the soil poisson ratio, and further temperature linear expansion parameters input in ABAQUS finite elements can be obtained:
β＝0.01α
therefore, the temperature linear expansion coefficient when the water content changes is calculated according to different working conditions and is input into ABAQUS finite element software;
s3, establishing corresponding material models for the tower foundation model and the unsaturated expansive soil foundation model respectively, wherein the tower foundation model selects an ideal elastic model, the unsaturated expansive soil foundation model selects an elastic-plastic molar-coulomb model, and corresponding material attributes are input respectively.
a. and (3) analyzing the ground stress balance: the device is used for eliminating the deformation of the unsaturated expansive soil foundation model caused by gravity;
b. a first static load analysis step: applying normal operation load to the pole tower foundation model, calculating the deformation and stress field distribution of the unsaturated expansive soil foundation model under the operation load condition, obtaining a stress cloud picture of the unsaturated expansive soil foundation model shown in figure 4 and a displacement cloud picture of the unsaturated expansive soil foundation model shown in figure 5, and simultaneously ensuring that the water content value in the unsaturated expansive soil foundation model in the analysis step and the previous analysis steps is uniformly distributed and kept unchanged, wherein omega is 18%;
c. and (3) expansion calculation analysis step: the distribution condition of the water content in the unsaturated expansive soil foundation under the actual engineering condition is equivalently simulated by predefining a temperature field in an unsaturated expansive soil foundation model in ABAQUS, and the change process of the water content of the unsaturated expansive soil foundation model in the atmospheric influence depth range of the earth surface soil body is simulated by changing the distribution condition of the temperature field, wherein the atmospheric influence depth range of the earth surface soil body is 5m, the water content omega of the earth body in the range is 7.65 percent, namely the water loss shrinkage of the earth surface soil body caused by dry climate, so that the expansion and shrinkage deformation of the unsaturated expansive soil foundation caused by the change of the water content and the change condition of the bearing capacity characteristic of the unsaturated expansive soil foundation are calculated;
d. and a second static force calculation analysis step: applying a load to the tower foundation model for calculating the foundation bearing capacity of the unsaturated expansive soil foundation model after the water content is redistributed;
(1) selecting a proper grid size, setting the type of grid unit as a three-dimensional eight-node one-time integral entity reduction integral unit C3D8R, and carrying out grid division on the unsaturated expansive soil foundation model and the tower foundation model;
(2) setting boundary conditions of the unsaturated expansive soil foundation model: constraining the displacement of the unsaturated expansive soil foundation model in three directions at the bottom and the horizontal displacement corresponding to four surfaces at the periphery;
(3) applying gravity load to the unsaturated expansive soil foundation model in the ground stress balance analysis step, and ensuring that the gravity load is continuously applied in the subsequent analysis step;
(4) applying upper loads including a downward pressing load, an upward pulling load and a combined load to the pole tower foundation model in the static load analysis step one, wherein the upper loads are determined by actual engineering conditions, the upper load value in the embodiment in the market is 240kPa, and the upper loads are ensured to continue to the expansion calculation analysis step;
(5) applying a predefined temperature field to the unsaturated expansive soil foundation model from the initial analysis step to equivalently simulate the distribution condition of the water content in the unsaturated expansive soil foundation under the actual engineering condition, wherein the predefined temperature field is determined according to the distribution condition of the water content in the unsaturated expansive soil foundation at the actual engineering location, and the predefined temperature field is ensured to be kept unchanged before the expansion calculation analysis step;
(6) changing the distribution condition of the water content in the unsaturated expansive soil foundation within the depth range of the atmospheric influence of the earth surface soil body in the expansion calculation analysis step, and calculating the expansion and contraction deformation of the unsaturated expansive soil foundation model caused by the change of the water content of the unsaturated expansive soil foundation so as to obtain the expansion and contraction deformation of the tower foundation model and the stress distribution condition in the unsaturated expansive soil foundation model generated thereby, so that the displacement condition of the tower foundation model generated by the water content distribution change in the unsaturated expansive soil foundation model can be obtained;
(7) and in the static calculation and analysis step two, changing the load value of the upper part of the tower foundation model, and calculating the bearing capacity of the unsaturated expansive soil foundation model under the new humidity field distribution condition, so that the change condition of the bearing capacity of the unsaturated expansive soil foundation model caused by the change of the water content can be obtained.
(a) distribution of stress and displacement field of unsaturated expansive soil foundation model under upper load
As shown in fig. 4 and 5, which are a stress cloud and a displacement cloud of the unsaturated expansive soil foundation model in the present embodiment, respectively, it can be seen that the stress and strain distribution in the unsaturated expansive soil foundation model is mainly concentrated in the range near the bottom of the foundation, and the unsaturated expansive soil foundation has no destruction phenomenon because the upper load is not particularly large; in general, the distribution of stress and strain (here, strain is also displacement) in the unsaturated expansive soil foundation soil body can be obtained through the analysis step.
(b) The expansion process caused by the change of the water content causes the redistribution of the stress and displacement field of the unsaturated expansive soil foundation model
For the unsaturated expansive soil foundation which is deformed and stabilized under the action of the upper load of the tower foundation model, the water content of the soil body within the depth range (5m) influenced by the surface atmosphere is changed, so that the expansion and contraction effect of unsaturated expansive soil can be caused, and the displacement deformation of the tower foundation and the change of the internal force in the soil body of the unsaturated expansive soil foundation and the tower foundation can be inevitably caused due to the expansion and contraction of the soil body;
fig. 6 is a schematic diagram showing the distribution of the humidity field in the unsaturated expansive soil foundation model after the step of expansion calculation and analysis in this embodiment;
fig. 7 is a cloud diagram of stress distribution in the unsaturated expansive soil foundation model after the expansion calculation and analysis step in this embodiment;
fig. 8 is a cloud diagram of displacement distribution in the unsaturated expansive soil foundation model after the expansion calculation and analysis step in this embodiment;
fig. 9 is a cloud diagram of equivalent plastic strain in the unsaturated expansive soil foundation model after the expansion calculation and analysis step in this embodiment;
as is apparent from the calculation results shown in fig. 6 to 9, the stress in the unsaturated expansive soil foundation model and the tower foundation model changes significantly due to the change of the water content, and a plastic region is generated in the upper soil body of the unsaturated expansive soil foundation which originally has no plastic strain due to the expansion and contraction deformation of the unsaturated expansive soil, so that the influence degree of the expansion and contraction effect of the unsaturated expansive soil on the tower foundation can be seen;
in addition, as shown in fig. 10, it is a displacement time curve of the top of the tower foundation and the soil body on the surface of the unsaturated expansive soil foundation during the expansion calculation analysis step in this embodiment, as can be seen from fig. 10, when the water content of the soil body on the surface of the unsaturated expansive soil foundation changes from 18% to 7.65%, the soil body on the surface generates significant shrinkage settlement, and as the tower foundation is deeper buried, the settlement of the tower foundation is less, and the settlement of the soil body on the surface of the unsaturated expansive soil foundation is more, so that the soil body on the unsaturated expansive soil foundation applies a downward acting force to the tower foundation.
(c) Foundation bearing capacity of unsaturated expansive soil foundation model after water content is redistributed
After the expansion calculation and analysis step, internal forces caused by the expansion and contraction effects of the unsaturated expansive soil are generated in the unsaturated expansive soil foundation model and the tower foundation model, and in addition, the change of the water content of the unsaturated expansive soil also causes the change of the strength of the unsaturated expansive soil, so that the foundation bearing capacity of the unsaturated expansive soil foundation model after the water content is changed needs to be further calculated and analyzed.
As shown in fig. 11, it is a stress distribution cloud chart in the unsaturated expansive soil foundation model after the water content is redistributed in this embodiment;
as shown in fig. 12, it is a displacement distribution cloud chart in the unsaturated expansive soil foundation model after the water content is redistributed in this embodiment;
as shown in fig. 13, it is an equivalent plastic strain cloud chart in the unsaturated expansive soil foundation model after the water content is redistributed in this embodiment;
as can be seen from fig. 11 to 13, the plastic region originally in the upper portion of the unsaturated expansive soil foundation model occurs in the lower soil body of the unsaturated expansive soil foundation model due to the action of the upper load, and as the plastic region develops, the soil body of the unsaturated expansive soil foundation finally breaks, as shown in fig. 14, the load displacement curve is the load displacement curve of the unsaturated expansive soil foundation model reaching the ultimate bearing capacity after the moisture content is redistributed in the embodiment.
In this embodiment, the depth range of the atmospheric influence of the earth surface soil body is 5m, and obviously, other depth ranges of the atmospheric influence of the earth surface soil body, such as 3m or 4m, may be selected according to the soil quality and environment of different regions.
Finally, the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting, and other modifications or equivalent substitutions made by the technical solutions of the present invention by those of ordinary skill in the art should be covered within the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solutions of the present invention.
Claims (7)
1. A numerical analysis method for stability of a tower foundation on an unsaturated expansive soil foundation is characterized by mainly comprising the following steps:
step 1, establishing a tower foundation model and an unsaturated expansive soil foundation model: according to the size information of a tower foundation in actual engineering, establishing a tower foundation model and an unsaturated expansive soil foundation model by using ABAQUS three-dimensional finite element analysis software;
step 2, respectively establishing material attributes of the tower foundation model and the unsaturated expansive soil foundation model: respectively carrying out a triaxial test on unsaturated expansive soil under different water content conditions to obtain material parameters of the unsaturated expansive soil, taking the obtained material parameters of the unsaturated expansive soil as the material parameters of an unsaturated expansive soil foundation model under different water content conditions, and taking the material parameters of a tower foundation as the material parameters of a tower foundation model; assembling the tower foundation model and the unsaturated expansive soil foundation model which are built according to the material properties, and setting normal contact parameters and tangential contact parameters between the two models;
step 3, establishing the following analysis steps:
a. and (3) analyzing the ground stress balance: the device is used for eliminating the deformation of the unsaturated expansive soil foundation model caused by gravity;
b. a first static load analysis step: the method is used for analyzing the deformation condition of the tower foundation model under the normal operation load condition of the unsaturated expansive soil foundation model;
c. and (3) expansion calculation analysis step: the distribution condition of the water content in the unsaturated expansive soil foundation under the actual engineering condition is equivalently simulated by predefining the temperature field in the unsaturated expansive soil foundation model in ABAQUS, and the change process of the water content of the unsaturated expansive soil foundation model within the depth range influenced by the earth surface soil atmosphere is simulated by changing the distribution condition of the temperature field, so that the expansion and contraction deformation of the unsaturated expansive soil foundation and the change condition of the bearing capacity characteristic thereof caused by the change of the water content are calculated;
d. and a second static force calculation analysis step: applying a load to the tower foundation model for calculating the foundation bearing capacity of the unsaturated expansive soil foundation model after the water content is redistributed;
step 4, carrying out grid division on the pole tower foundation model and the unsaturated expansive soil foundation model, setting boundary conditions for restraining the displacement of the bottom and the periphery of the unsaturated expansive soil foundation model, and applying gravity load and corresponding upper load of the pole tower foundation model;
step 5, submitting operation and analyzing the operation result;
the step 2 specifically comprises the following steps:
s1, performing a basic physical mechanical test on the unsaturated expansive soil to obtain related physical parameters of the unsaturated expansive soil foundation under different initial water content conditions;
wherein the material parameters of the unsaturated expansive soil foundation model are
S2, determining the density, the elastic modulus and the Poisson ratio of the tower foundation model material according to the actual engineering condition;
wherein the material parameters of the tower foundation model are
According to an indoor no-load expansion rate test performed on unsaturated expansive soil, fitting the relation between the expansion rate and the initial water content of the unsaturated expansive soil as follows:
thereby obtaining different initial water content omega1And final water content omega2Corresponding expansion ratio deltaps1And deltaps2According to the theory related to the equivalent humidity field of the temperature field, the linear expansion coefficient caused by the change of the humidity field is as follows:
in the formula: ν is the soil poisson ratio, and further temperature linear expansion parameters input in ABAQUS finite elements can be obtained:
β＝0.01α
therefore, the temperature linear expansion coefficient when the water content changes is calculated according to different working conditions and is input into ABAQUS finite element software;
s3, establishing corresponding material models for the tower foundation model and the unsaturated expansive soil foundation model respectively, wherein the tower foundation model selects an ideal elastic model, the unsaturated expansive soil foundation model selects an elastic-plastic molar-coulomb model, and corresponding material attributes are input respectively.
2. The method for numerically analyzing the stability of the tower foundation on the unsaturated expansive soil foundation according to claim 1, wherein the method comprises the following steps: in the step S1, the basic physical mechanical tests performed on the unsaturated expansive soil include a soil density test, a water content test, a liquid-plastic limit test, a compressibility test, an expansibility test, and a triaxial test.
3. The method for numerically analyzing the stability of the tower foundation on the unsaturated expansive soil foundation according to claim 2, wherein the method comprises the following steps: in the step S1, a basic physical mechanical test is performed on the unsaturated expansive soil to obtain relevant physical parameters of the unsaturated expansive soil foundation under different initial water content conditions, including cohesion, internal friction angle, soil density, natural water content, liquid-plastic limit parameter, expansion characteristic parameter and compression characteristic parameter.
4. The method for numerically analyzing the stability of the tower foundation on the unsaturated expansive soil foundation according to any one of claims 1 to 2, wherein the step 4 specifically comprises the following steps:
(1) selecting a proper grid size, setting the type of grid unit as a three-dimensional eight-node one-time integral entity reduction integral unit C3D8R, and carrying out grid division on the unsaturated expansive soil foundation model and the tower foundation model;
(2) setting boundary conditions of the unsaturated expansive soil foundation model: constraining the displacement of the unsaturated expansive soil foundation model in three directions at the bottom and the horizontal displacement corresponding to four surfaces at the periphery;
(3) applying gravity load to the unsaturated expansive soil foundation model in the ground stress balance analysis step, and ensuring that the gravity load is continuously applied in the subsequent analysis step;
(4) applying an upper load comprising a downward pressing load, an upward pulling load and a combined load to the pole tower foundation model in the static load analysis step I, wherein the upper load is determined by actual engineering conditions and is ensured to continue to the expansion calculation analysis step;
(5) applying a predefined temperature field to the unsaturated expansive soil foundation model from the initial analysis step to equivalently simulate the distribution condition of the water content in the unsaturated expansive soil foundation under the actual engineering condition, wherein the predefined temperature field is determined according to the distribution condition of the water content in the unsaturated expansive soil foundation at the actual engineering location, and the predefined temperature field is ensured to be kept unchanged before the expansion calculation analysis step;
(6) changing the distribution condition of the water content in the unsaturated expansive soil foundation within the depth range of the atmospheric influence of the earth surface soil body in the expansion calculation analysis step, and calculating the expansion and contraction deformation of the unsaturated expansive soil foundation model caused by the change of the water content of the unsaturated expansive soil foundation so as to obtain the expansion and contraction deformation of the tower foundation model and the stress distribution condition in the unsaturated expansive soil foundation model generated thereby, so that the displacement condition of the tower foundation model generated by the water content distribution change in the unsaturated expansive soil foundation model can be obtained;
(7) and in the static calculation and analysis step two, changing the load value of the upper part of the tower foundation model, and calculating the bearing capacity of the unsaturated expansive soil foundation model under the new humidity field distribution condition, so that the change condition of the bearing capacity of the unsaturated expansive soil foundation model caused by the change of the water content can be obtained.
5. The method for analyzing the numerical value of the stability of the tower foundation on the unsaturated expansive soil foundation according to any one of claims 1 to 2, wherein in the step 5, the analysis of the operation result comprises distribution of a humidity field, stress, strain and a plastic zone in the unsaturated expansive soil foundation model, and deformation characteristics generated by bearing capacity of the tower foundation model and a dilatancy effect of unsaturated expansive soil.
6. The method for numerically analyzing the stability of the tower foundation on the unsaturated expansive soil foundation according to any one of claims 1 to 2, wherein: the size of the unsaturated expansive soil foundation model is 3.0-5.0 times of that of the tower foundation model.
7. The method for numerically analyzing the stability of the tower foundation on the unsaturated expansive soil foundation according to any one of claims 1 to 2, wherein: the atmospheric influence depth range of the earth surface soil body is 3.0-5.0 m.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711185166.5A CN107958113B (en) | 2017-11-23 | 2017-11-23 | Numerical analysis method for stability of tower foundation on unsaturated expansive soil foundation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711185166.5A CN107958113B (en) | 2017-11-23 | 2017-11-23 | Numerical analysis method for stability of tower foundation on unsaturated expansive soil foundation |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN107958113A CN107958113A (en) | 2018-04-24 |
| CN107958113B true CN107958113B (en) | 2021-10-22 |
Family
ID=61961766
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201711185166.5A Active CN107958113B (en) | 2017-11-23 | 2017-11-23 | Numerical analysis method for stability of tower foundation on unsaturated expansive soil foundation |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN107958113B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108661089B (en) * | 2018-05-17 | 2020-06-12 | 同济大学 | Numerical analysis method for ultimate expansion shear force of pile foundation in expansive land area |
| CN109388865B (en) * | 2018-09-25 | 2022-10-21 | 武汉大学 | Tower emergency failure early warning method under ground settlement working condition |
| CN109376429B (en) * | 2018-10-24 | 2022-10-11 | 中国水利水电第七工程局有限公司 | Concrete dam template safety construction analysis method based on finite element simulation |
| CN109736157A (en) * | 2019-02-25 | 2019-05-10 | 长沙理工大学 | Highway Expansive Soil Roadbed Slope deformation prediction method based on wetting balance |
| CN110852004B (en) * | 2019-08-23 | 2024-10-01 | 成都理工大学 | Mechanical seepage coupling unsaturated soil numerical simulation method and system |
| CN110749723A (en) * | 2019-11-05 | 2020-02-04 | 国家电网有限公司 | Physical model test method for high-voltage transmission tower foundation landslide under rainfall effect |
| CN113515654B (en) * | 2021-04-30 | 2022-09-23 | 中冶建工集团有限公司 | Pile foundation construction parameter visualization processing method and device based on building information modeling |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102262022A (en) * | 2011-07-14 | 2011-11-30 | 同济大学 | Test method for simulating shear resistant strength change of foundation pit precipitation soil |
| CN103760089A (en) * | 2014-01-29 | 2014-04-30 | 山东农业大学 | Experiment-numerical analysis combined determination method for relative permeability coefficient of unsaturated soil |
| CN103967037A (en) * | 2014-05-12 | 2014-08-06 | 新乡华源电力勘察设计有限公司 | Pole and tower rigid foundation optimum design method |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6244280B2 (en) * | 2014-08-29 | 2017-12-06 | 株式会社奥村組 | Unsaturated seepage characteristics analysis method by VG model |
| KR101547090B1 (en) * | 2015-05-26 | 2015-08-25 | 연세대학교 산학협력단 | Method and system for fully coupled analysis of rainfall infiltration and slope stability using unsaturated constitutive model in sandy soils |
-
2017
- 2017-11-23 CN CN201711185166.5A patent/CN107958113B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102262022A (en) * | 2011-07-14 | 2011-11-30 | 同济大学 | Test method for simulating shear resistant strength change of foundation pit precipitation soil |
| CN103760089A (en) * | 2014-01-29 | 2014-04-30 | 山东农业大学 | Experiment-numerical analysis combined determination method for relative permeability coefficient of unsaturated soil |
| CN103967037A (en) * | 2014-05-12 | 2014-08-06 | 新乡华源电力勘察设计有限公司 | Pole and tower rigid foundation optimum design method |
Non-Patent Citations (2)
| Title |
|---|
| 云桂高速铁路膨胀土路堑基床动静力学特性数值分析;房以河;《中国优秀硕士学位论文全文数据库 工程科技Ⅱ辑》;20150315;第2015年卷(第3期);正文第2-4章 * |
| 膨胀土地基输电线杆塔基础承载力特性数值模拟;吕玺琳 等;《水利与建筑工程学报》;20171031;第15卷(第5期);正文第1-4节 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN107958113A (en) | 2018-04-24 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN107958113B (en) | Numerical analysis method for stability of tower foundation on unsaturated expansive soil foundation | |
| Tang et al. | A novel approach for determining landslide pushing force based on landslide-pile interactions | |
| Ye et al. | Numerical study on load transfer effect of Stiffened Deep Mixed column-supported embankment over soft soil | |
| Waichita et al. | Characterization of deep cement mixing wall behavior using wall-to-excavation shape factor | |
| CN108661089B (en) | Numerical analysis method for ultimate expansion shear force of pile foundation in expansive land area | |
| Zhang et al. | Three dimensional numerical simulation of residential building on shrink–swell soils in response to climatic conditions | |
| AU2021106123A4 (en) | Method for Calculating the Ultimate Expansion Shear Force of Expansive Soil Pile Foundation Based on Finite Element Simulation | |
| Wu et al. | Dynamic characteristics and seismic response analysis of the bottle-shaped masonry ancient pagoda | |
| Yang et al. | Stability analysis of shallow tunnels subjected to seepage with strength reduction theory | |
| Al Aqtash et al. | Numerical approach to model the effect of moisture in adobe masonry walls subjected to in-plane loading | |
| Xiong et al. | A numerical study and simulation of vertical bearing performance of step-tapered pile under vertical and horizontal loads | |
| Carpinteri et al. | Numerical assessment of three medieval masonry towers subjected to different loading conditions | |
| CN106021664A (en) | Method for analyzing influences, caused by beaded-shaped karst, on pile foundation stressed deformation | |
| Dalili et al. | Numerical simulation of soil-structure interaction in framed and shear-wall structures | |
| Tristá et al. | Aplicación de la caracterización de suelos parcialmente saturados en la modelación del comportamiento resistente de cimientos aislados sometido a carga axial. | |
| Vaskova et al. | Subsoil-structure interaction solved in different FEM programs | |
| Wu et al. | Numerical Modeling of Deformation Response of Embankment Subjected to Rainfall Infiltration Considering the Hydro-Mechanical Coupled Behavior of Unsaturated Soils | |
| Sokolov et al. | Modeling of geomechanical processes case of uneven settling of foundations constructions | |
| Zhang et al. | Numerical investigation of vertically loaded pile on adjacent tunnel considering soil spatial variability | |
| Le et al. | Bearing characteristics of mono-column composite bucket foundations for offshore wind turbines in layered soil | |
| Motalebian et al. | Numerical estimation of the fundamental frequency of improved sites with stone columns | |
| Zhong | Determination of bearing capacity of a sand-mudstone interbedded foundation in Chengdu | |
| Pan et al. | Failure probability assessment of Fujian earth buildings under multi-disaster coupling | |
| Gao | Research on the Seismic Performance of Highly Durable Concrete Structures with Corrosion-resistant Reinforcing Steel Materials | |
| Xiao-song et al. | Application of numerical ultimate analysis in identifying the bearing capacity of foundation |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |