CN117421860A - Unified characterization method for multi-type shear curve of roadbed soil under complex conditions - Google Patents
Unified characterization method for multi-type shear curve of roadbed soil under complex conditions Download PDFInfo
- Publication number
- CN117421860A CN117421860A CN202311167313.1A CN202311167313A CN117421860A CN 117421860 A CN117421860 A CN 117421860A CN 202311167313 A CN202311167313 A CN 202311167313A CN 117421860 A CN117421860 A CN 117421860A
- Authority
- CN
- China
- Prior art keywords
- shearing
- roadbed
- strain
- curves
- confining pressure
- 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.)
- Pending
Links
- 239000002689 soil Substances 0.000 title claims abstract description 72
- 238000012512 characterization method Methods 0.000 title claims abstract description 17
- 238000010008 shearing Methods 0.000 claims abstract description 89
- 238000012360 testing method Methods 0.000 claims abstract description 73
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 64
- 238000005482 strain hardening Methods 0.000 claims abstract description 25
- 238000013178 mathematical model Methods 0.000 claims abstract description 24
- 230000006641 stabilisation Effects 0.000 claims abstract description 20
- 238000011105 stabilization Methods 0.000 claims abstract description 20
- 238000005056 compaction Methods 0.000 claims description 17
- 238000000034 method Methods 0.000 claims description 9
- 238000007596 consolidation process Methods 0.000 claims description 3
- 238000007405 data analysis Methods 0.000 claims description 3
- 238000004364 calculation method Methods 0.000 abstract description 9
- 238000004458 analytical method Methods 0.000 description 4
- 230000008859 change Effects 0.000 description 4
- 239000004927 clay Substances 0.000 description 4
- 230000014509 gene expression Effects 0.000 description 4
- 238000010606 normalization Methods 0.000 description 4
- 239000011435 rock Substances 0.000 description 4
- 230000000087 stabilizing effect Effects 0.000 description 4
- 238000010257 thawing Methods 0.000 description 4
- 238000013461 design Methods 0.000 description 2
- 201000010099 disease Diseases 0.000 description 2
- 208000037265 diseases, disorders, signs and symptoms Diseases 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 239000004576 sand Substances 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 238000012795 verification Methods 0.000 description 2
- 230000003313 weakening effect Effects 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000003755 preservative agent Substances 0.000 description 1
- 230000002335 preservative effect Effects 0.000 description 1
Classifications
-
- 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
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2111/00—Details relating to CAD techniques
- G06F2111/10—Numerical modelling
-
- 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
- G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Theoretical Computer Science (AREA)
- Computer Hardware Design (AREA)
- Evolutionary Computation (AREA)
- Geometry (AREA)
- General Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Road Paving Structures (AREA)
Abstract
The invention discloses a unified characterization method of a road foundation soil multi-type shearing curve under a complex condition, which comprises the following steps: designing a roadbed earth monotone loading test scheme capable of comprehensively covering roadbed earth by taking possible consideration of moisture content, compactness, confining pressure and shearing rate, obtaining shearing curves of the roadbed earth under different working conditions through tests, and determining influence characteristics of each factor on the roadbed earth shearing curves respectively; based on the shearing curves under different working conditions, a mathematical model capable of uniformly describing three types of shearing curves of strain hardening, strain stabilization and strain softening under the complex condition of roadbed soil is provided; fitting the established mathematical model by using test data under different working conditions to obtain model parameters under different working conditions, and establishing a multi-element and multi-form functional relation between the model parameters and the water content, the compactness, the confining pressure and the shear rate; and by means of the established mathematical model and the multivariate functional relation, different types of shearing curves of the roadbed soil under complex conditions are represented, and the calculation efficiency and the convergence are improved.
Description
Technical Field
The invention belongs to the technical field of road engineering, and relates to a unified characterization method of a road foundation soil multi-type shearing curve under a complex condition.
Background
Under the influence of complex environment and external load, the weakening of the shearing capacity of soil mass causes the problems of permanent strain unsteady accumulation, slope unsteady slump, excessive settlement deformation and the like of the roadbed frequently, so that the roadbed serving as a pavement foundation cannot exert the functions of firmness, durability and the like, the road structure is caused to generate a plurality of diseases such as rutting, cracking and the like, and the stability and the safety of road transportation are seriously influenced. From the source, the generation of roadbed diseases is caused by weakening of the shearing capacity of roadbed soil, and a shearing curve is the basis and source for analyzing the shearing capacity of roadbed soil. Due to the complex environment and stress state of the roadbed soil and different shearing speeds caused by construction speed, the shearing curve of the roadbed soil shows three types of strain hardening, strain stabilization and strain softening under different working conditions, and reasonable and effective characterization description of the shear curve is an important problem of continuous attention in the current road engineering field.
The research (Chang Dan, et al, geotechnical mechanics, 2015,36 (12)) of stress-strain normalization characteristics of silt clay under freeze thawing cycle is based on a traditional Duncan-tension model, a normalization description method of strain hardening type curves which can only consider influences of freeze thawing cycle and confining pressure is provided for silt clay, but influences of moisture content, compactness and shear rate caused by roadbed humidification and different filling rates cannot be considered, the proposed model is not suitable for strain softening curves, if the softening curves need to be described, other models are needed to be used, and a plurality of expressions are needed to describe different types of shear curves separately, at the moment, when numerical computation is carried out by embedding the expressions of different types into each finite element computing platform, the existing method needs to judge the deformation type of the soil according to the stress state of the soil, then the deformation curves of different types of the soil are simulated according to the set judgment basis, once grids of each expression are more or the computing model are relatively dense, the number of times of the needed judgment is relatively increased, the cost of the computation is not calculated, the computation is very high, and the computation is not time-consuming and the computation process is easy to stop because of the computation is very long. The mechanical property of the expansion rock and the stress-strain normalization thereof under the dry-wet-freeze thawing cycle (Zeng Zhixiong, etc. the rock-soil mechanics, 2018,39 (08): 2895-2904.) provide a normalization description method of three types of shear curves of strain hardening, strain stabilization and strain softening which consider the influences of the freeze thawing cycle and the confining pressure aiming at the expansion rock, but do not consider the influences of the moisture content, the compactness and the shear rate, and the confining pressure level in the test is basically between 200 and 400kPa at the same time, which is far from the low confining pressure stress state of the roadbed, the obtained result has better guidance on the high confining pressure scene of the foundation, the actual characteristics of the engineering with the roadbed are very different, and the expansion rock can not be used for filling the roadbed, so that the prior art is not suitable for representing the three types of shear curves of strain hardening, strain stabilization and strain softening of the roadbed. The chinese patent application No. 202310004989.2 discloses a red clay hardening curve which can only consider the influence of confining pressure and fiber content and length, the influence on moisture content, compactibility, shear rate and the availability of strain softening curve. The stress-strain relationship and the nonlinear Moire Strength criterion of frozen sand (Lai Yuanming, et al, proc. Ind. Of rock mechanics and engineering, 2007,187 (8): 1612-1617.) disclose models that can describe three types of shear curves for frozen soil strain hardening, strain stabilization, strain softening simultaneously, but cannot uniformly characterize the shear curves at different moisture contents, compactibility, and shear rates. Aiming at the problem that three types of shear curves of road foundation soil under different water contents, compactibility, confining pressure, shear rate, strain hardening, strain stabilization and strain softening cannot be simultaneously described at present, a unified characterization method of the road foundation soil multi-type shear curves under complex conditions is urgently required to be developed.
Disclosure of Invention
In order to achieve the aim, the invention provides a unified characterization method of multi-type shear curves of roadbed soil under complex conditions, which solves the problem that three types of shear curves of roadbed soil with different water contents, compactness, confining pressure and shear rate can not be simultaneously described at present.
In order to solve the technical problems, the technical scheme adopted by the invention is that the unified characterization method of the multi-type shear curve of the roadbed soil under the complex condition comprises the following steps:
step S1: designing a possible roadbed earth monotone loading test scheme capable of comprehensively covering roadbed earth by taking the water content, compactness, confining pressure and shearing rate into consideration, obtaining shearing curves of roadbed earth under different working conditions, namely different water content, compactness, confining pressure and shearing rate, and determining the influence characteristics of the water content, compactness, confining pressure and shearing rate on the roadbed earth shearing curves respectively;
step S2: based on the shearing curves under different working conditions obtained in the step S1, a mathematical model capable of uniformly describing three types of shearing curves of strain hardening, strain stabilization and strain softening under complex conditions of roadbed soil is provided;
step S3: fitting the mathematical model established in the step S2 by using the test data under different working conditions in the step S1 to obtain model parameters under different working conditions, and establishing a multi-element and multi-form functional relation between the model parameters and factors such as water content, compactness, confining pressure, shearing rate and the like;
step S4: and (3) characterizing three types of shearing curves of strain hardening, strain stabilization and strain softening of roadbed soil under complex conditions of different water contents, compactness, confining pressure and the like through the mathematical model established in the steps (S2) to (S3) and the multivariate functional relation.
Further, step S2 proposes a mathematical model capable of uniformly describing three types of shear curves of strain hardening, strain stabilization and strain softening under complex conditions of roadbed soil as shown in the following formula:
wherein: sigma is the axial stress; epsilon is the axial strain; p, q, k are model parameters.
Further, in step S3, a multi-functional relationship between the model parameters p, q, k and the water content, compactness, confining pressure is established as shown in the following formula:
wherein w is water content, OMC is optimal water content, K is compactness, sigma 3 Is confining pressure.
Further, in step S1:
in the roadbed soil monotonic loading test scheme, the water content is calculatedThe level was selected to be 1.0OMC, 1.2OMC, 1.4OMC, 1.6OMC, the compaction level was selected to be 87%, 90%, 93%, 96%, the confining pressure level was selected to be 30kPa, 60kPa, 90kPa, 120kPa, and the shear rate level was selected to be 0.50% min -1 、0.70％min -1 、0.85％min -1 1.00% min -1 The designed monotonic loading test scheme is shown in the following table:
| group number | Degree of compaction (%) | Water content/OMC | Shear rate (% min) -1 ) | Confining pressure (kPa) |
| 1 | 96 | 1.0 | 0.70 | 30、60、90、120 |
| 2 | 93 | 1.0 | 0.70 | 30、60、90、120 |
| 3 | 90 | 1.0 | 0.70 | 30、60、90、120 |
| 4 | 87 | 1.0 | 0.70 | 30、60、90、120 |
| 5 | 96 | 1.2 | 0.70 | 30、60、90、120 |
| 6 | 96 | 1.4 | 0.70 | 30、60、90、120 |
| 7 | 96 | 1.6 | 0.70 | 30、60、90、120 |
| 8 | 96 | 1.2 | 0.50 | 30、60、90、120 |
| 9 | 96 | 1.2 | 0.85 | 30、60、90、120 |
| 10 | 96 | 1.2 | 1.00 | 30、60、90、120 |
；
The monotone loading test adopts a mode of non-consolidation and non-drainage, and the loading is stopped when the axial strain reaches 15%.
In step S3, the mathematical model established in step S2 is fitted by using the test data under different working conditions in step S1, and a planning and solving function in Matlab data analysis is adopted during the fitting, and the fitting is completed when the decision coefficient reaches the maximum value.
The beneficial effects of the invention are as follows:
1. the method has the advantages that the commonalities of different types of shearing curves under different working conditions are grasped, the mathematical models which are used for uniformly describing three types of shearing curves, namely roadbed strain hardening, strain stabilization and strain softening, are provided, wherein the linear elastic phase of the shearing curves is described by straight lines, the plastic part of the shearing curves is described by hyperbolas, and the constant part is used for adjusting the adaptability, the description of the different types of shearing curves of the roadbed can be realized by using only one uniform expression, the deformation types of the roadbed do not need to be judged in advance, the model parameters are clear in meaning and simple to obtain, the calculation efficiency and the calculation convergence are greatly improved, and the calculation time during the actual problem analysis of roadbed deformation analysis, slope safety coefficient and the like is saved; the phenomenon that the shearing rate has little influence on the soil shearing curve in the roadbed scene is found, and experiments prove that the shearing rate variable can be not considered when the shearing curve model is built, so that the influence factors of the model are reasonably reduced, and the estimation efficiency is improved; moreover, a relation equation between parameters p, q and k of a unified model of the shearing curve and the moisture content, the compaction degree and the confining pressure is established, so that the shearing curve under the corresponding working condition can be quickly obtained according to the physical state and the stress state of the roadbed soil, the problem that three types of shearing curves of different moisture contents, compaction degree, confining pressure, roadbed soil strain hardening, strain stabilization and strain softening cannot be simultaneously described at present is solved, and obvious engineering convenience is provided for engineering disasters and participating units of a series of shearing performance indexes obtained by the shearing curve and the soil shearing curve are needed to be obtained rapidly, and the method has high practical value;
2. the designed test scheme is fully proposed for the actual scene of the roadbed, particularly, the confining pressure level is set to be 30kPa, 60kPa, 90kPa and 120kPa according to the low confining pressure characteristic of the roadbed, so that the problems of incompatibility and the like caused by different actual characteristics when the phenomenon, conclusion and model obtained by the test carried out under the high confining pressure level in the prior art are applied to the shear deformation analysis of roadbed soil are avoided, and the larger deviation of the technology obtained by using the high confining pressure condition in guiding roadbed engineering is avoided;
3. the test scheme capable of comprehensively covering the influence factors of the road foundation soil shearing curve is designed, the scheme comprehensively considers the influence of the water content, the compactness, the confining pressure and the shearing rate, reduces the number of soil samples in the test to 40 to reveal the influence of different factors, avoiding the huge test amount of 4 x 4=256 test pieces in four-factor four-level comprehensive test, the complex process of sample preparation is greatly reduced, the difficulty of monotonic shear test is reduced, the test time consumption is shortened, and the research efficiency is improved.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a flowchart of a unified characterization method of a multi-type shear curve of a roadbed under a complex condition in the embodiment.
Fig. 2 is a test flow chart of a unified characterization method of a multi-type shear curve of a roadbed soil under the complex condition of the embodiment.
FIG. 3 is a shear curve of test pieces of foundation soil under different water contents and different confining pressures.
FIG. 4 is a shear curve of test pieces of foundation soil under different compactibility and different confining pressures.
FIG. 5 is a graph of shear curves for test pieces of foundation soil at different shear rates and different confining pressures.
Fig. 6 shows the variation law of the parameter p of the unified model of the shear curve with the water content, the compactness and the confining pressure.
Fig. 7 shows the variation law of the parameter q of the unified model of the shear curve with the water content, the compactness and the confining pressure.
Fig. 8 shows the variation law of the parameter k of the unified model of the shear curve with the water content, the compactness and the confining pressure.
Fig. 9 shows the effect of predicting the multivariate functional relationship of the parameters p, q, k of the unified model of the shear curve.
Fig. 10 is a verification result of the multivariate function relation of parameters p, q, k of the shear curve unified model.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
The embodiment of the invention discloses a unified characterization method of a multi-type shear curve of roadbed soil under a complex condition, which is shown in fig. 1, and is specifically carried out according to the following steps S1-S4.
Step S1: the design of a possible roadbed earth monotone loading test scheme capable of comprehensively covering roadbed earth by considering water content, compactness, confining pressure and shearing rate, and obtaining shearing curves of roadbed earth under different working conditions, namely different water content, compactness, confining pressure and shearing rate, by test, and defining the influence characteristics of factors (water content, compactness, confining pressure and shearing rate) on the roadbed earth shearing curves respectively:
according to the balance state of the roadbed humidity, taking the balance water content as a benchmark and taking the fact that the roadbed humidity is increased under the humidification action into consideration, selecting the water content level as 1.0OMC, 1.2OMC, 1.4OMC and 1.6OMC in the optimal water content (OMC) and the humidity measurement; the compactness level is selected to be 87%, 90%, 93% and 96% according to the partition requirements of 96%, 94% and 93% when roadbed filling and considering the attenuation of the compactness in the service period; considering that the roadbed filling is generally about 6m in most cases, the confining pressure level is selected to be 30kPa, 60kPa, 90kPa and 120kPa according to 20kPa per meter; the shear rate level was selected to be 0.50% min -1 、0.70％min -1 、0.85％min -1 1.00% min -1 To cover the possible loading rates in the roadbed;
determining the maximum dry density and the optimal water content (OMC) of roadbed soil according to a compaction test result, adopting a split membrane device to obtain a test piece under the target compactness and the water content by static pressure under a universal hydraulic testing machine, carrying out a monotone loading test according to a table 1 by adopting a mode of not solidifying and not draining after the test piece stands for 2 days, stopping loading when the axial strain reaches 15%, and further analyzing the influence of each factor on a shearing curve according to the shearing curve test result, wherein the influence of the compactness is analyzed in 1-4 groups, the influence of the water content is analyzed in 1-5-7 groups, the influence of the shearing rate is analyzed in 5-8-10 groups, and the influence of the confining pressure can be reflected in each group.
Table 1 monotonic loading test protocol table
| Group number | Degree of compaction (%) | Containing waterRate/OMC | Shear rate (% min) -1 ) | Confining pressure (kPa) |
| 1 | 96 | 1.0 | 0.70 | 30、60、90、120 |
| 2 | 93 | 1.0 | 0.70 | 30、60、90、120 |
| 3 | 90 | 1.0 | 0.70 | 30、60、90、120 |
| 4 | 87 | 1.0 | 0.70 | 30、60、90、120 |
| 5 | 96 | 1.2 | 0.70 | 30、60、90、120 |
| 6 | 96 | 1.4 | 0.70 | 30、60、90、120 |
| 7 | 96 | 1.6 | 0.70 | 30、60、90、120 |
| 8 | 96 | 1.2 | 0.50 | 30、60、90、120 |
| 9 | 96 | 1.2 | 0.85 | 30、60、90、120 |
| 10 | 96 | 1.2 | 1.00 | 30、60、90、120 |
Step S2: based on the shearing curves under different working conditions obtained in the step S1, a mathematical model capable of uniformly describing three types of shearing curves of strain hardening, strain stabilization and strain softening under complex conditions of roadbed soil is provided;
step S3: fitting the mathematical model established in the step S2 by using the test data under different working conditions in the step S1 to obtain model parameters under different working conditions, and establishing a multi-element and multi-form functional relation between the model parameters and factors such as water content, compactness, confining pressure, shearing rate and the like;
step S4: and (3) characterizing three types of shear curves of road foundation soil strain hardening, strain stabilization and strain softening under complex conditions of different water contents, compactibility, confining pressure and the like through the mathematical model established in the steps S2 to S3 and the multivariate functional relation:
substituting arbitrary water content, compactness and confining pressure into the multi-functional relation between the model parameters p, q and k established in the step S3 and the water content, compactness and confining pressure, and obtaining the model parameters p, q and k under the combination of the arbitrary water content, compactness and confining pressure, so that three types of shearing curves of road foundation strain hardening, strain stabilization and strain softening under complex conditions are represented by the mathematical model proposed in the step S2.
Example 2
The embodiment provides a unified characterization method of a road foundation soil multi-type shearing curve under a complex condition, which comprises the following steps:
taking low liquid limit clay from Hunan long sand as an example, the basic physical parameters are shown in table 2, and the test soil sample selected in the example is qualified roadbed filling soil according to the liquid limit of less than 50% and the plasticity index of less than 26.
TABLE 2 basic physical parameters of soil samples
Step S1: the design of a possible roadbed earth monotone loading test scheme capable of comprehensively covering roadbed earth by considering water content, compactness, confining pressure and shearing rate, and obtaining shearing curves of roadbed earth under different working conditions, namely different water content, compactness, confining pressure and shearing rate, by test, and defining the influence characteristics of various factors (water content, compactness, confining pressure and shearing rate) on the roadbed earth shearing curves:
determining that the maximum dry density of the roadbed soil is 1.71 g.cm according to the compaction test result -3 The optimal water content (OMC) is 14.2 percent; test protocol reference is made to step S1 of example 1: the water content level of the test soil sample is selected to be 1.0OMC, 1.2OMC, 1.4OMC and 1.6OMC, performing operation; the compactness level of the test soil sample is selected to be 87%, 90%, 93% and 96%; the test confining pressure level is selected to be 30kPa, 60kPa, 90kPa and 120kPa; the shear rate level was selected to be 0.50% min -1 、0.70％min -1 、0.85％min -1 1.00% min -1 The method comprises the steps of carrying out a first treatment on the surface of the Test pieces with target compactness and water content are obtained by adopting a split film under a universal hydraulic testing machine through 5 layers of static pressure, the finished piece stands for 2 days after being sealed by a preservative film, then a monotone loading test is carried out in a Triaxial-100/14 Triaxial system produced by Italy WF company in a non-consolidation and non-drainage mode according to a table 1, main steps in a test flow are shown in figure 2, loading is stopped when axial strain reaches 15%, wherein the influence of compactness is analyzed in 1-4 groups, the influence of water content is analyzed in 1, 5-7 groups, the influence of shear rate is analyzed in 5, 8-10 groups, and the influence of confining pressure can be reflected in each group: the shearing curves of the test soil samples under different water contents and different confining pressures are shown in the figure 3, the (a) of the figure 3 is a shearing curve of a roadbed soil test sample under the confining pressure of 30kPa, the (b) of the figure 3 is a shearing curve of a roadbed soil test sample under the confining pressure of 60kPa, the (c) of the figure 3 is a shearing curve of a roadbed soil test sample under the confining pressure of 90kPa, the (d) of the figure 3 is a shearing curve of a roadbed soil test sample under the confining pressure of 120kPa, the influence of the water contents and the confining pressure on the shearing curve is obvious, when the water contents and the confining pressures are changed, the numerical value of the shearing curve is changed, and three types of strain hardening, strain stabilization and strain softening appear under different working conditions; the shear curves of the test soil samples under different compaction degrees and different confining pressures are shown in fig. 4, the shear curve of the road base soil test pieces under the 30kPa confining pressure and different compaction degrees is shown in fig. 4 (a), the shear curve of the road base soil test pieces under the 60kPa confining pressure and different compaction degrees is shown in fig. 4 (b), the shear curve of the road base soil test pieces under the 90kPa confining pressure and different compaction degrees is shown in fig. 4 (d), the shear curve of the road base soil test pieces under the 120kPa confining pressure and different compaction degrees is shown in fig. 4, and the compaction degree has a remarkable influence on the shear curve as shown in fig. 4 through the same analysis; the shear curves of the test soil samples under different shear rates and different confining pressures are shown in FIG. 5, and FIG. 5 (a) shows a road with different shear rates under 30kPa confining pressureThe shear curve of the foundation soil test piece is shown in fig. 5 (b) which is a shear curve of the foundation soil test piece with different shear rates under the surrounding pressure of 60kPa, fig. 5 (c) which is a shear curve of the foundation soil test piece with different shear rates under the surrounding pressure of 90kPa, and fig. 5 (d) which is a shear curve of the foundation soil test piece with different shear rates under the surrounding pressure of 120kPa, wherein the type and the numerical value of the shear curve are not influenced by the change of the shear rate, and the test curves under the different shear rates are relatively fit;
step S2: based on the shearing curves under different working conditions obtained in the step S1, a mathematical model capable of uniformly describing three types of shearing curves of strain hardening, strain stabilization and strain softening under the complex condition of roadbed soil is provided:
as can be seen from the test results of the shearing curves under different working conditions shown in fig. 3, 4 and 5 in the step S1, although the types of the three types of the curves of strain hardening, strain stabilizing and strain softening are obviously different, the three types of the shearing curves of the strain hardening, the strain stabilizing and the strain softening are all wired elastic parts and plastic parts, based on the commonality, the line elastic stage of the shearing curve is described by adopting a straight line, the plastic part of the shearing curve is described by adopting a hyperbola, and the adaptability of the constant part adjusting model is described by adopting a hyperbola, so that a mathematical model which is shown in the following formula and can uniformly describe the three types of the shearing curves of the strain hardening, the strain stabilizing and the strain softening under the complex condition of the roadbed soil is provided:
wherein: sigma is the axial stress; epsilon is the axial strain; p, q and k are model parameters and can be obtained through monotonic loading test results;
step S3: fitting the mathematical model established in the step S2 by using the test data under different working conditions in the step S1 to obtain model parameters under different working conditions, and establishing a multi-element and multi-form functional relation between the model parameters and factors such as water content, compactness, confining pressure, shearing rate and the like:
fitting the mathematical model established in the step S2 by using test data under different working conditions in the step S1, adopting a planning and solving function in Matlab data analysis during fitting, and finishing fitting when the decision coefficient reaches the maximum value, wherein the fitting result is shown in a table 3;
table 3 parameter statistics table of unified model of shear curve
Then, according to the results in table 3, the evolution rules of the model parameters p, q, k along with the influence factors are analyzed, and the results are shown in fig. 6-8, where (a) to (c) in fig. 6 correspond to the change rules of the parameter p along with the moisture content, the compactness and the confining pressure, and (a) to (c) in fig. 7 correspond to the change rules of the parameter q along with the moisture content, the compactness and the confining pressure, and (a) to (c) in fig. 8 correspond to the change rules of the parameter k along with the moisture content, the compactness and the confining pressure. To ensure the tightness and integrity of the model establishment, the parameters of the 40 working conditions shown in table 3 are independently used in two parts: the first part selects 32 working conditions to establish the following model, and the second part selects the other 8 working conditions to verify the rationality and accuracy of the unified characterization method of the road foundation soil multi-type shearing curve under the proposed complex condition. Since the test results in step S1 clearly show that the shear rate has little effect on the shear curve, the shear rate is no longer a factor of influence. Specifically, as can be seen from fig. 6, the parameter p varies exponentially with the compaction, logarithmically with the ratio of the actual water content to the optimal water content, and exponentially with the confining pressure; as can be seen from fig. 7, the parameter q varies linearly with the compaction, exponentially with the ratio of the actual water content to the optimal water content, and logarithmically with the confining pressure; as can be seen from fig. 8, the parameter k varies exponentially with the degree of compaction, exponentially with the ratio of the actual water content to the optimal water content, and power-function with the confining pressure. Furthermore, the corresponding description forms are selected respectively, and a multi-functional relation (model parameters in the functional relation are properly amplified in consideration of magnitude reasons) shown in the following formula between parameters p, q and k of a shearing curve unified model and the water content, compactness and confining pressure is established:
wherein w is water content, OMC is optimal water content, K is compactness, sigma 3 Is confining pressure;
the accuracy of the multivariate functional relationship of model parameters p, q, k is shown in FIG. 9, and the correspondence of FIGS. 9 (a) - (c) is parameter 10 2 X p, parameter 10 5 X q, parameter 10 3 The result of the relation between the actual value and the predicted value of the xk, wherein N is the number of used working conditions, namely the number of modeled sample points, and R 2 The prediction precision of the multi-element function relation of the parameters p, q and k which are all larger than 0.9 is very high;
step S4: and (3) characterizing three types of shear curves of road foundation soil strain hardening, strain stabilization and strain softening under complex conditions of different water contents, compactibility, confining pressure and the like through the mathematical model established in the steps S2 to S3 and the multivariate functional relation:
the monotonic loading test scheme designed in the step S1 is 40 working conditions in total, 32 working conditions are used in the step S3 when the multi-element function relation of the model parameters p, q and k is established, in order to verify the rationality and accuracy of the proposed unified model of the shearing curve and the multi-element function relation of the model parameters p, q and k, the water content, compactness and confining pressure in the rest 8 working conditions are substituted into the multi-element function relation established in the step S3 so as to further obtain the corresponding model parameters p, q and k, and then substituted into the mathematical model of the shearing curve proposed in the step S2 so as to obtain the calculation result of the shearing curve corresponding to 8 working conditions, the comparison result of the calculation value and the measured value is shown in fig. 10, the (a) - (h) of fig. 10 are the comparison result of the calculation value and the measured value corresponding to the verification working condition 8, the broken line represents the calculation value of the shearing curve, the hollow point represents the calculated value of the shearing curve, the three types of the curve of strain softening, strain hardening and strain stabilizing can be highly matched, and the calculation value and the measured value are proved to represent the unified soil of the multi-basic curve under the complex condition of the complex foundation condition of the proposed in the implementation.
The foregoing description is only of the preferred embodiments of the present invention and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.
Claims (5)
1. The unified characterization method of the road foundation soil multi-type shear curve under the complex condition is characterized by comprising the following steps:
step S1: designing a possible roadbed earth monotone loading test scheme capable of comprehensively covering roadbed earth by taking the water content, compactness, confining pressure and shearing rate into consideration, obtaining shearing curves of roadbed earth under different working conditions, namely different water content, compactness, confining pressure and shearing rate, and determining the influence characteristics of the water content, compactness, confining pressure and shearing rate on the roadbed earth shearing curves respectively;
step S2: based on the shearing curves under different working conditions obtained in the step S1, a mathematical model capable of uniformly describing three types of shearing curves of strain hardening, strain stabilization and strain softening under complex conditions of roadbed soil is provided;
step S3: fitting the mathematical model established in the step S2 by using the test data under different working conditions in the step S1 to obtain model parameters under different working conditions, and establishing a multi-element and multi-form functional relation between the model parameters and factors of water content, compactness, confining pressure and shear rate;
step S4: and (3) representing three types of shear curves of road foundation soil strain hardening, strain stabilization and strain softening under complex conditions of different water contents, compactness and confining pressure by the mathematical model and the multivariate functional relation established in the steps (S2) to (S3).
2. The unified characterization method of the multi-type shear curve of the roadbed under the complex condition according to claim 1, wherein the step S2 is characterized in that a mathematical model capable of describing three types of shear curves of strain hardening, strain stabilization and strain softening under the complex condition of the roadbed is provided as shown in the following formula:
wherein: sigma is the axial stress; epsilon is the axial strain; p, q, k are model parameters.
3. The unified characterization method of the road foundation soil multi-type shearing curve under the complex condition according to claim 2, wherein the step S3 is characterized in that a multi-functional relation between model parameters p, q and k and water content, compactness and confining pressure is established, wherein the multi-functional relation is shown in the following formula:
wherein w is water content, OMC is optimal water content, K is compactness, sigma 3 Is confining pressure.
4. A method for uniformly characterizing a multi-type shear curve of a roadbed under a complex condition according to any one of claims 1 to 3, wherein in step S1:
in the roadbed soil monotonous loading test scheme, the water content level is selected to be 1.0OMC, 1.2OMC, 1.4OMC and 1.6OMC, the compactness level is selected to be 87%, 90%, 93% and 96%, the confining pressure level is selected to be 30kPa, 60kPa, 90kPa and 120kPa, and the shearing rate level is selected to be 0.50% min -1 、0.70％min -1 、0.85％min -1 1.00% min -1 The designed monotonic loading test scheme is shown in the following table:
；
The monotone loading test adopts a mode of non-consolidation and non-drainage, and the loading is stopped when the axial strain reaches 15%.
5. The unified characterization method of the multi-type shear curve of the roadbed under the complex conditions according to any one of claims 1 to 3, wherein in the step S3, the mathematical model established in the step S2 is fitted by using the test data under different working conditions in the step S1, a planning and solving function in Matlab data analysis is adopted during fitting, and the fitting is ended when the coefficient is determined to reach the maximum value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311167313.1A CN117421860A (en) | 2023-09-11 | 2023-09-11 | Unified characterization method for multi-type shear curve of roadbed soil under complex conditions |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311167313.1A CN117421860A (en) | 2023-09-11 | 2023-09-11 | Unified characterization method for multi-type shear curve of roadbed soil under complex conditions |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117421860A true CN117421860A (en) | 2024-01-19 |
Family
ID=89531457
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311167313.1A Pending CN117421860A (en) | 2023-09-11 | 2023-09-11 | Unified characterization method for multi-type shear curve of roadbed soil under complex conditions |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117421860A (en) |
-
2023
- 2023-09-11 CN CN202311167313.1A patent/CN117421860A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN107679293B (en) | Method for mutually optimizing indoor mechanical parameters and rolling construction parameters of rock-fill dam | |
| Yao et al. | Model for predicting resilient modulus of unsaturated subgrade soils in south China | |
| Zhang et al. | Prediction of resilient modulus of compacted cohesive soils in South China | |
| Yang et al. | Suction-controlled laboratory test on resilient modulus of unsaturated compacted subgrade soils | |
| Indraratna et al. | Numerical analysis of matric suction effects of tree roots | |
| CN109142118B (en) | Roadbed soil dynamic resilience modulus estimation method based on state variables and stress variables | |
| CN108645676B (en) | Method for detecting and evaluating damage of roadbed soil material in seasonal frozen region based on ultrasonic technology | |
| CN113640505B (en) | Permanent deformation prediction method for crushed stone-clay mixed filler | |
| CN108362593B (en) | Roadbed soil resilience modulus estimation method based on substrate suction and minimum body stress | |
| CN105260509A (en) | Method for determining temperature process curve of ultrahigh fly-ash content hydraulic massive concrete | |
| Ma et al. | Hydraulic and mechanical behavior of unsaturated silt: Experimental and theoretical characterization | |
| CN110702541B (en) | Road foundation soil multistage dynamic loading accumulated deformation test method under humidification effect | |
| Bayat et al. | The 3D analysis and estimation of transient seepage in earth dams through PLAXIS 3D software: neural network: Case study: Kord-Oliya Dam, Isfahan province, Iran | |
| CN110083879A (en) | A kind of inside concrete temperature and humidity linear accelerator method based on network | |
| CN114324023B (en) | Rapid prediction method for breaking strength of construction waste roadbed filler | |
| CN107860655A (en) | A kind of overhead transmission line collapsible loess foundation ess-strain simulates method | |
| CN116266239A (en) | Estimation method for permanent deformation of high-liquid-limit clay | |
| CN110826807B (en) | Method for rapidly predicting dynamic resilience modulus of roadbed filler in seasonal frozen region | |
| CN107894367A (en) | A kind of transmission line of electricity collapsible loess constitutive modeling method | |
| Zhang | Limitations of suction‐controlled triaxial tests in the characterization of unsaturated soils | |
| Akbari Garakani et al. | An effective stress-based DSC model for predicting the coefficient of lateral soil pressure in unsaturated soils | |
| CN106950357A (en) | A kind of double-admixing concrete cracking resistance appraisal procedure | |
| CN117421860A (en) | Unified characterization method for multi-type shear curve of roadbed soil under complex conditions | |
| CN109518574B (en) | Method for determining equivalent resilience modulus of roadbed top surface under humidification effect | |
| CN111508567A (en) | Method and device for analyzing freeze-thaw damage characteristics of asphalt mixture |
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 |