Soil stress and dependent variable prediction method based on MICP (Minimum Inductively Coupled Plasma)

Abstract

The invention provides a soil stress and dependent variable prediction method based on MICP. The soil stress and dependent variable prediction method comprises the following steps: S1, constructing an initial yield surface formula of a soil body based on a secondary loading surface theory; s2, adding an MICP cementing reinforcement stress expression into the initial yield surface formula to obtain a final yield surface formula; and S3, differentiating the secondary loading surface corresponding to the final yield surface formula obtained in the S2 to obtain a soil mass mechanical model. The method has the beneficial effects that by correcting the peak stress ratio, introducing the MICP cementation enhanced stress and considering factors such as over-consolidation, the soil behavior under the action of a single factor can be accurately simulated, the comprehensive mechanical property under the combined action of the soil behavior and the MICP cementation enhanced stress can be simulated, and the prediction accuracy is improved by adding the yield surface degradation equation in the model.

Description

Technical Field

[0001] This invention belongs to the field of site soil reinforcement technology, and in particular relates to a method for predicting soil stress and strain based on MICP. Background Technology

[0002] Site soil reinforcement is an important component of modern foundation treatment. The most common methods for soil reinforcement include compaction, preloading, vibration, and chemical grouting, or a combination of these methods. However, all of these methods incur significant costs or generate environmental pollution. Soil cementation can improve its resistance to failure under static or dynamic loads. Microbial soil reinforcement technology utilizes substances generated by microorganisms to fill and cement soil particles, thereby improving the engineering performance of the soil and rock mass. Compared to traditional soil reinforcement techniques, it has advantages such as less environmental impact, greater sustainability, and relatively lower cost. Among microbial reinforcement technologies, microbial-induced calcium carbonate precipitation (MICP) is the most researched and widely applied.

[0003] Different overconsolidated soils under saturated conditions exhibit different mechanical properties after undergoing different degrees of MIP treatment. Current soil mechanics models cannot describe the mechanical properties of overconsolidated saturated soils under MIP cementation and cementation degradation, leading to inaccurate prediction of strain. Summary of the Invention

[0004] In view of this, the present invention aims to propose a method for predicting soil stress and strain based on MICP, in order to solve at least one of the above-mentioned technical problems.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows: The first aspect of this invention provides a method for predicting soil stress and strain based on MICP, comprising the following steps: S1. Formula for the initial yield surface of soil based on secondary loading surface theory; S2. By adding the MICP cementation reinforcement stress expression to the initial yield surface formula, the final yield surface formula is obtained. S3. Differentiate the secondary loading surface corresponding to the final yield surface formula obtained in S2 to obtain the soil mechanics model; S4. Collect the physical and mechanical parameters of the soil to be predicted, and substitute the physical and mechanical parameters into the soil mechanics model to obtain the prediction model. S5. Input the target stress into the prediction model to obtain the predicted strain, or input the target strain into the prediction model to obtain the predicted stress.

[0006] Furthermore, the initial yield surface formula in S1 is: ; in, It is a deviatoric stress. For effective average stress, Peak stress ratio These are hardening parameters. ; in, The slope of the normal compression curve. The slope of the rebound curve. This represents the initial void ratio.

[0007] Furthermore, the final yield surface formula in S2 is as follows: ; in, The pre-consolidation pressure is calculated as consolidation stress under consolidated conditions and as the maximum historical stress of the formation under overconsolidated conditions. MICP is used to reinforce stress.

[0008] Furthermore, the hardening parameters in S3 It is the only corresponding function for volumetric strain, fitting the shear dilatation phenomenon that occurs in the soil after reinforcement in the early stage of loading; Hardening parameters The formula is as follows: ; in, For unit plastic strain, Corrected peak stress ratio =q / p.

[0009] Furthermore, the corrected peak stress ratio formula is as follows: ; in, Let Vorslev's envelope slope be the slope of the overconsolidated soil. Let be the slope of the Voslev envelope of MICP cemented soil. The stress ratio is the overconsolidation ratio. The stress ratio represents the degree of bonding.

[0010] Furthermore, the formula for the stress ratio of the overconsolidation ratio is as follows: ; The formula for the stress ratio of the degree of bonding is as follows: ; This is the consolidation stress.

[0011] in The formula for calculating the MICP bond reinforcement stress is as follows: , It is the cementation reinforcement stress coefficient. Calcium carbonate mass fraction This is the cementation degradation rate parameter.

[0012] Furthermore, in S3, the flow rule is the associated flow rule, the plastic flow direction is the same as the yield surface normal direction, and the plastic potential function is the same as the yield surface function. After adding plastic strain and elastic strain to the yield surface formula in S2, the soil mechanics model formula is obtained by differentiating the second loading surface. The soil mechanics model formula in S3 is as follows: ; in, ; ; ; For elastic bulk modulus, Shear modulus For the body to adapt to strain, For partial strain.

[0013] Furthermore, the formula for calculating the bulk modulus of elasticity is as follows: ; Porosity; The formula for calculating the shear modulus is as follows: ,in The value is Poisson's ratio of the soil being tested.

[0014] Furthermore, in S3, the plastic potential function is as follows: ; For plastic strain, For yield surface, For stress

[0015] The plastic compliance in different directions can be obtained by taking the total differential of the yield surface and using the hardening parameters; the formula is as follows: ; The unit deviatoric stress; Unit elastic strain includes unit elastic body strain and unit elastic deviatoric strain, and the specific formulas are as follows: ; ; unit elastic strain For unit elastic deviatoric strain, For the initial porosity, For Poisson's ratio, For the slope of the rebound curve, It is a deviatoric stress. This represents the effective average stress.

[0016] A second aspect of the present invention provides an electronic device, including a processor and a memory communicatively connected to the processor and used to store processor-executable instructions, characterized in that: the processor is used to execute the method described in the first aspect above.

[0017] Compared with existing technologies, the soil stress and strain prediction method based on MICP described in this invention has the following advantages: The present invention discloses a method for predicting soil stress and strain based on MICP. By correcting the peak stress ratio, introducing MICP cementation-enhanced stress, and considering overconsolidation, this method can not only accurately simulate soil behavior under the action of a single factor, but also simulate the comprehensive mechanical properties when both factors act together. By adding a yield surface degradation equation to the model, the prediction accuracy is improved. Attached Figure Description

[0018] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the prediction method described in an embodiment of the present invention. Detailed Implementation

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0020] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0022] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] like Figure 1 As shown, a method for predicting soil stress and strain based on MICP includes the following steps: S1. Formula for the initial yield surface of soil based on secondary loading surface theory; S2. By adding the MICP cementation reinforcement stress expression to the initial yield surface formula, the final yield surface formula is obtained. S3. Differentiate the secondary loading surface corresponding to the final yield surface formula obtained in S2 to obtain the soil mechanics model; S4. Collect the physical and mechanical parameters of the soil to be predicted, and substitute the physical and mechanical parameters into the soil mechanics model to obtain the prediction model. S5. Input the target stress into the prediction model to obtain the predicted strain, or input the target strain into the prediction model to obtain the predicted stress.

[0024] The formula for the initial yield surface in S1 is: ; in, It is a deviatoric stress. For effective average stress, Peak stress ratio These are hardening parameters. ; in, The slope of the normal compression curve. The slope of the rebound curve. This represents the initial void ratio.

[0025] The final yield surface formula in S2 is as follows: ; in, The pre-consolidation pressure is calculated as consolidation stress under consolidated conditions and as the maximum historical stress of the formation under overconsolidated conditions. MICP is used to reinforce stress.

[0026] By combining the yield criterion of soil with the MICP cementation reinforcement stress, a model relating to stress, soil physical properties, and hardening parameters was derived.

[0027] The revised model incorporates cementation-enhancing stress, enabling it to effectively describe the change in soil yield surface caused by MICP cementation. By considering the soil's strengthening properties after cementation, the model more closely reflects real-world conditions. The final yield surface formula ensures more accurate predictions for cemented or overconsolidated soils, especially when cementation and overconsolidation work together.

[0028] The hardening parameters in S3 It is the only corresponding function for volumetric strain, fitting the shear dilatation phenomenon that occurs in the soil after reinforcement in the early stage of loading; Hardening parameters The formula is as follows: ; in, For unit plastic strain, Corrected peak stress ratio =q / p.

[0029] The corrected peak stress ratio formula is as follows: ; in, Let Vorslev's envelope slope be the slope of the overconsolidated soil. Let be the slope of the Voslev envelope of MICP cemented soil. The stress ratio is the overconsolidation ratio. The stress ratio represents the degree of bonding.

[0030] As the degree of overconsolidation increases, the failure rate gradually decreases, which can be obtained from the failure points of soil under different stress paths in the experiment. Similar to the definition of overconsolidated soil, its value decreases with increasing reinforcement, as can be determined experimentally.

[0031] when equal to 1 or and When they are equal, the influence of overconsolidation on the mechanical behavior of soil disappears, and the soil returns to a normally consolidated state, with the peak stress ratio... Regressing to the peak stress ratio based on the improved MICP constitutive model .

[0032] when equal to 1 or and When they are equal, the effect of MICP on soil mechanical behavior disappears, and the soil returns to its state before MICP cementation, with the peak stress ratio being equal. Peak stress ratio of the UH model .

[0033] By using the modified peak stress ratio formula, and combining the different characteristics of overconsolidated soil and MICP cemented soil, the stress state of soil under different conditions can be described more accurately.

[0034] By adjusting the peak stress ratio formula, the model can adapt to the characteristics of different soil types and simulate mechanical behavior under different load conditions, providing a more detailed and accurate reference for engineering design.

[0035] The formula for the stress ratio of overconsolidation ratio is as follows: ; The formula for the stress ratio of the degree of bonding is as follows: ; This is the consolidation stress.

[0036] in The formula for calculating the MICP bond reinforcement stress is as follows: , It is the cementation reinforcement stress coefficient. Calcium carbonate mass fraction This is the cementation degradation rate parameter.

[0037] The formula for calculating the cementation degradation rate parameter is as follows: ; —Unit plastic deviatoric strain, — The cementation degradation rate coefficient is a constant that defines the damage rate of the enhanced cementation mechanical behavior of calcium carbonate precipitation.

[0038] In S3, the flow rule is the associated flow rule, the plastic flow direction is the same as the yield surface normal direction, and the plastic potential function is the same as the yield surface function. After adding plastic strain and elastic strain to the yield surface formula in S2, the soil mechanics model formula is obtained by differentiating the second loading surface. The soil mechanics model formula in S3 is as follows: ; in, ; ; ; For elastic bulk modulus, Shear modulus For the body to adapt to strain, For partial strain.

[0039] The formula for calculating the bulk modulus of elasticity is as follows: ; Porosity; The formula for calculating the shear modulus is as follows: ,in The value is Poisson's ratio of the soil being tested.

[0040] In S3, the plastic potential function is as follows: ; For plastic strain, For yield surface, For stress

[0041] The plastic strain in different directions can be obtained by taking the total differential of the yield surface through the hardening parameters; the formula is as follows: ; dq is the unit deviatoric stress.

[0042] Unit elastic strain includes unit elastic body strain and unit elastic deviatoric strain, and the specific formulas are as follows: ; ; unit elastic strain For unit elastic deviatoric strain, For the initial porosity, For Poisson's ratio, For the slope of the rebound curve, It is a deviatoric stress. This represents the effective average stress.

[0043] By introducing overconsolidation ratio and cementation stress ratio, the model can handle more real-world soil conditions, especially those affected by varying degrees of overconsolidation and cementation enhancement. This is crucial for predicting the mechanical behavior of soils after soil improvement and reinforcement, enabling it to handle not only conventional soil behavior but also provide more accurate mechanical responses after soils have undergone different treatments (such as cementation and consolidation).

[0044] By modifying the peak stress ratio, introducing MIP cementation reinforcement stress, and considering overconsolidation, we can not only accurately simulate the soil behavior under a single factor, but also simulate the comprehensive mechanical properties when both factors work together.

[0045] By introducing the yield surface degradation equation into the model and improving the physical parameters of the soil according to the characteristics of MICP cementation, the mechanical behavior of overconsolidated saturated soil under MICP action can be better described.

[0046] The physical and mechanical parameters of the soil to be predicted collected in S4 include the following: Based on the type of soil to be predicted, it can be divided into the following categories: 1. Physical and mechanical parameters to be collected for untreated normally consolidated saturated soil and MIP normally consolidated saturated soil consolidated with drainage: , , , , , , , For the initial consolidation pressure ; 2. Physical and mechanical parameters to be collected for untreated normally consolidated saturated soil, MIP normally consolidated saturated soil, and consolidated undrained soil: , , , , , , ; 3. Physical and mechanical parameters to be collected for consolidated drained saturated soils with different overconsolidation ratios without MICP treatment: , , , , ,

[0047] 4. Physical and mechanical parameters to be collected for consolidated undrained saturated soils with different overconsolidation ratios without MICP treatment: , , , , , , ; 5. Physical and mechanical parameters to be collected for consolidated drained over-consolidated saturated soils with different degrees of MICP treatment: , , , , , , , , ; Example 2: An electronic device includes a processor and a memory communicatively connected to the processor and used to store processor-executable instructions, the processor being used to execute the method described in Embodiment 1 above.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for MICP-based soil stress and strain amount prediction, characterized in that, The method comprises the following steps: S1, constructing an initial yield surface formula of the soil body based on the sub-loading surface theory; S2, adding a MICP cementation reinforcement stress expression to the initial yield surface formula to obtain a final yield surface formula; S3, obtaining a soil mechanics model by differentiating the final yield surface formula obtained in S2; S4, collecting physical and mechanical parameters of the soil body to be predicted, and substituting the physical and mechanical parameters into the soil mechanics model to obtain a prediction model; S5, inputting a target stress into the prediction model to obtain a predicted strain, or inputting a target strain into the prediction model to obtain a predicted stress.

2. The MICP-based soil stress and strain amount prediction method according to claim 1, characterized in that, The initial yield surface formula in S1 is as follows: ； wherein, is the deviatoric stress, is the effective mean stress, is the peak stress ratio, is the hardening parameter, ; wherein, is the slope of the normal compression curve, is the slope of the rebound curve, is the initial void ratio.

3. The MICP-based soil stress and strain amount prediction method of claim 2, wherein, The final yield surface formula in S2 is as follows: ； wherein, The pre-consolidation pressure is calculated as the consolidation stress in the case of consolidation and as the maximum stress in the case of over-consolidation according to the formation history. Stress is enhanced for MICP cementation.

4. The MICP-based soil stress and strain amount prediction method of claim 3, wherein: The hardening parameter in S3 is the only corresponding function of the volumetric strain, fitting the dilatancy phenomenon that occurs in the initial loading of the reinforced soil. Hardening parameter The formula is as follows: ； wherein, is the unit plastic body strain, is the corrected peak stress ratio, =q / p.

5. The MICP-based soil stress and strain amount prediction method of claim 4, wherein: The corrected peak stress ratio formula is as follows: ； wherein, is the slope of the Vesilev envelope for overconsolidated soils, is the slope of the Vesilev envelope for MICP cemented soils, is the stress ratio for overconsolidated ratio, is the stress ratio for cementation degree.

6. The MICP-based soil stress and strain amount prediction method of claim 5, wherein ； The stress ratio formula of the over-consolidation ratio is as follows: ； The stress ratio formula of the cementation degree is as follows: ； to consolidate stresses; wherein is the MICP cementation enhanced stress, the calculation formula is , is the cementation enhanced stress coefficient, calcium carbonate mass fraction, is the cementation degradation rate parameter.

7. The MICP-based soil stress and strain amount prediction method of claim 1, wherein: In S3, the flow rule is an associated flow rule, the plastic flow direction is the same as the normal direction of the yield surface, the plastic potential function is the same as the yield surface function, the yield surface formula in S2 is added with plastic strain and elastic strain, and the soil mechanics model formula is obtained by differentiating the sub-loading surface. ； wherein, ； ； ； is the elastic bulk modulus, is the shear modulus, is the bulk strain, is the deviatoric strain.

8. The MICP-based soil stress and strain amount prediction method of claim 7, wherein: The calculation formula of the elastic bulk modulus is as follows: ； Pore ratio; The calculation formula of the shear modulus is as follows: wherein is the Poisson's ratio of the test soil.

9. The MICP-based soil stress and strain amount prediction method of claim 8, wherein: In S3, the plastic potential function is as follows: ； for plastic strain, for yield surface, for stress; The plastic potential function is as follows: ； The full differential of the yield surface is as follows: dq is a unit deviatoric stress; ； ； unit elastic body strain unit elastic deviatoric strain, initial void ratio, Poisson's ratio, slope of the rebound curve, deviatoric stress, effective mean stress.

10. An electronic device, comprising a processor and a memory connected to the processor in communication, and configured to store executable instructions of the processor, characterized in that: The unit elastic strain includes a unit elastic bulk strain and a unit elastic deviatoric strain, and the specific formula is as follows: The processor is configured to execute the method in any one of claims 1-9.

Images