Foundation treatment design method considering cooperative deformation control of junction area of different treatment forms

Abstract

The invention relates to a foundation treatment design method considering cooperative deformation control of a junction area of different treatment forms, which considers differential settlement forms of the junction area of different foundation treatment forms and the influence of the differential settlement forms. And it is ensured that the slope ratio of the junction area of different foundation treatment forms does not exceed the limit value by adjusting foundation design parameters and differential settlement control measures. And finally, the construction drawing design scheme can meet the use requirements.

Description

Technical Field

[0001] The invention relates to the field of foundation treatment, in particular to a foundation treatment design method that takes into account the coordinated deformation control of interface areas of different treatment forms. Background Art

[0002] For soft foundations, due to their high compressibility and low bearing capacity, foundation treatment measures are generally required to meet the needs of engineering use. Currently, the commonly used soft foundation treatment methods mainly include replacement method, pre-compression consolidation method, composite foundation method and rigid pile foundation method. For large-scale foundation treatment projects with different settlement control standards, construction period requirements, and soft soil thickness, it is often necessary to use multiple foundation treatment methods in combination to optimize the engineering design and achieve a reasonable engineering cost.

[0003] At present, the foundation and foundation treatment specifications of various industries usually calculate the surface deformation of each conventional area of ​​various foundation treatment forms, directly subtract them to obtain the settlement difference, and control the uneven settlement with the limit of the settlement difference. And based on engineering experience, differential settlement control measures are taken within a certain range of the foundation treatment boundary area. Due to the difference in reinforcement mechanism, the post-construction settlement development characteristics of different foundation treatment forms are quite different, which makes the boundary area of ​​foundation treatment forms present different characteristics from conventional areas.

[0004] In summary, the current foundation treatment design methods have the following main problems: 1) The current foundation and foundation treatment specifications of various industries only control differential settlement through the settlement difference of non-intersection areas, and do not directly calculate the deformation of the junction area. The deformation form and characteristics of the junction area are unclear, and it is impossible to confirm whether the local surface slope meets the requirements, while the relevant specifications for buildings and pavements have limits on the surface slope; 2) The current calculation method does not consider the coupling effect of the two foundation treatment forms on the junction area, which is inconsistent with the actual situation. 3) The differential settlement control measures, treatment scope and treatment effect are mainly based on experience, and there is no calculation basis. Summary of the invention

[0005] The purpose of the present invention is to provide a foundation treatment design method that takes into account the coordinated deformation control of the interface area of ​​different treatment forms. While taking into account the differential settlement morphology and its influence at the interface area of ​​different foundation treatment forms, it ensures that the slope of the interface area of ​​different foundation treatment forms does not exceed the limit value by adjusting design parameters and measures.

[0006] The present invention is implemented by the following technical solution: a foundation treatment design method considering coordinated deformation control of interface areas of different treatment forms, comprising the following steps:

[0007] Step 1: Carry out the corresponding foundation treatment design according to different foundation treatment forms in accordance with the current specifications and obtain the foundation design parameters;

[0008] Step 2: According to the foundation design parameters and the stratum distribution in the geological survey report, a PLAXIS finite element model of the boundary area of ​​the foundation treatment form is constructed, and the model stratum parameters are calibrated using the geotechnical test parameters in the geological survey report;

[0009] Step 3: Based on the finite element model in step 2, calculate the change of the site surface settlement in each year after the project is put into use. Derivative the ground settlement with respect to the horizontal distance to obtain the change of the site surface slope in each year;

[0010] Step 4: Substitute the surface slope S of the site in each year in step 3 d Changes and current standard verification slope limit values ​​[S d ] to confirm the surface slope S of the site in each year. d Whether it exceeds the standard calibration slope limit [S d ]; if the surface slope S of the site in each year d Does not exceed the standard verification slope limit [S d ], it means that the design parameters of step 1 meet the requirements, and there is no need to increase or adjust the settlement control measures of the boundary area. The construction drawings are drawn according to the foundation design parameters;

[0011] Step 5: For example, the surface slope change S of the site in each year d Exceeding the standard calibration slope limit [S d ], for the areas with excessive slope around the boundaries of different foundation treatment forms, add differential settlement control measures or / and adjust the existing differential settlement control measures to form new foundation design parameters and return to step 2.

[0012] The beneficial effects of the present invention are as follows:

[0013] 1. The foundation treatment design is carried out based on the current specifications, and the finite element model is jointly generated in combination with the stratum parameters reported in the on-site geological survey. The surface settlement changes of the site in each year after the project is put into use are calculated, and then the surface slope changes of the site in each year are obtained, and the surface slope changes of the site in each year are calculated as S. d Verify the slope limit value with the standard [S d ] to provide a basis for subsequent adjustment of foundation design parameters and ultimately ensure that the construction drawing can meet site requirements.

[0014] 2. The elements for adding or adjusting settlement control measures in the boundary area were confirmed, providing a theoretical basis for subsequent calculations and on-site construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a flow chart of the present invention;

[0016] Figure 2Schematic diagram of the initial working condition of the composite foundation model of pile preloading and mixing piles;

[0017] Figure 3 Schematic diagram of graded pile loading conditions constructed for the pile preloading and mixing pile composite foundation model;

[0018] Figure 4 Schematic diagram of full load preloading condition constructed for the preloading and mixing pile composite foundation model;

[0019] Figure 5 For Figure 4 Schematic diagram of the working conditions of leveling the foundation and constructing mixing piles;

[0020] Figure 6 For Figure 5 Schematic diagram of the long-term consolidation condition after foundation construction;

[0021] Figure 7 It is a schematic diagram of the surface settlement curve when the post-construction consolidation of the simulated site is complete;

[0022] Figure 8 Schematic diagram of the surface slope curve at different post-construction times at different sites. DETAILED DESCRIPTION

[0023] The present invention is described in detail below in conjunction with the accompanying drawings:

[0024] like Figure 1 As shown: A foundation treatment design method considering coordinated deformation control of the interface area of ​​different treatment forms includes the following steps:

[0025] Step 1: Carry out corresponding foundation treatment design in different areas according to the current specifications and obtain foundation design parameters;

[0026] Step 2: According to the foundation design parameters and the stratum distribution in the geological survey report, a PLAXIS finite element model of the boundary area of ​​the foundation treatment form is constructed, and the model stratum parameters are calibrated using the geotechnical test parameters in the geological survey report;

[0027] Step 3: Based on the finite element model in step 2, calculate the change of the site surface settlement in each year after the project is put into use. Derivative the ground settlement with respect to the horizontal distance, and the surface slope S of the site in each year can be obtained. d Changes in circumstances;

[0028] Step 4: Substitute the surface slope S of the site in each year in step 3 d Changes and current standard verification slope limit values ​​[S d ] to confirm the surface slope S of the site in each year. d Whether it exceeds the standard calibration slope limit [S d]; if the surface slope S of the site in each year d Does not exceed the standard verification slope limit [S d ], it means that the design parameters of step 1 meet the requirements, and there is no need to increase or adjust the settlement control measures of the boundary area. The construction drawings are drawn according to the foundation design parameters;

[0029] Step 5: For example, the surface slope change S of the site in each year d Exceeding the standard calibration slope limit [S d ], for the areas with excessive slope around the intersection of different foundation treatment forms, add differential settlement control measures or / and adjust the existing differential settlement control measures to form new foundation design parameters and return to step 2. In step 1, various forms of foundation treatment design for different zones are first carried out according to the current building foundation and foundation treatment related specifications in a conventional way to determine the design parameters such as pile (plate) plane layout, pile diameter, pile length and material strength that meet the requirements of the project. Among them, the zones divided by different foundation treatment forms refer to the areas where different foundation treatment forms are located. For example, if preloading is used, it can be zone 1, and if a composite foundation is used, it can be zone 2. The area with excessive slope is within a range at the intersection of the zones, and the slope may exceed the limit.

[0030] Furthermore, in step 2, the finite element model of the boundary area of ​​the foundation treatment form is calculated and set according to the actual construction conditions.

[0031] Furthermore, the specific algorithm for the change of the site surface slope in each year in step 3 is that the surface settlement S of the site in each year changes with the horizontal position x, that is, S = f(x). The surface slope (differential settlement) S of the site in each year can be obtained by taking the derivative of the ground settlement S with respect to the horizontal position x. d With the change of horizontal position, that is: S d =f′(x).

[0032] Furthermore, the standard check slope limit [S d ] According to the corresponding specifications of different zones, the selection is made. Specifically, the surface differential settlement limit in the specification is determined according to the use function of the site, such as stadiums, runways and roads. d ]. Based on the specification limit [S d ] as the standard, check whether the calculation results of the finite element model for the differential settlement of the site surface in each year exceed the limit. If the differential settlement of the site surface during the post-construction period does not exceed the limit value of the specification, that is, S d =f′(x)≤[S d ], the construction drawings can be drawn directly according to the original design parameters and construction can be carried out.

[0033] If the differential settlement of some areas at the horizontal position x∈(a,b) exceeds the limit, that is, S d =f′(x)>[Sd ],x∈(a,b), then the out-of-limit range x∈(a,b) is recorded.

[0034] It should be noted that for the area with excessive slope, according to the construction period, cost and treatment effect of different treatment measures, the differential settlement treatment measures such as increasing the pile spacing, setting geotechnical reinforcement materials and frame plates are initially formulated based on engineering experience, and the treatment range can be appropriately extended according to the characteristics of the treatment measures. For example, if the extension length is c, the distribution range of the treatment measures is the area at the horizontal position x∈(ac,b+c). And add corresponding treatment measures within the horizontal position x∈(ac,b+c) in the finite element model.

[0035] Based on the finite element model with differential settlement treatment measures added, the changes in the site surface slope (differential settlement) in each year after the project was put into use were calculated. d ] as the standard, check whether the calculation results of the differential settlement of the site surface in each year exceed the limit. If the differential settlement and the cost of measures meet the requirements, the construction drawings can be drawn directly according to the design parameters and construction can be carried out.

[0036] If there is still an over-limit or if there is no over-limit but the cost of the measures is too high, the design parameters of the differential settlement control measures, such as pile spacing, geogrid strength and number of tracks, and frame plate thickness, can be adjusted, and the finite element model parameters can be modified to recalculate and verify. Repeat this step until the surface differential settlement and cost meet the requirements.

[0037] The following is an explanation based on current actual construction cases:

[0038] like Figure 2-6 As shown: According to the current specifications, the corresponding foundation treatment design is carried out in different forms of foundation treatment, and the foundation design parameters are obtained. Then, the preloading and mixing pile composite foundation model is built in combination with the stratum distribution in the geological survey report; Figure 2 The initial working condition of one of the partitions during the construction of the preloading and mixing pile composite foundation model. Figure 3 For graded loading conditions, Figure 4 It is the full load preload condition. Figure 5 To treat another partition, leveling and pile mixing were carried out. Figure 6 This is the long-term consolidation condition after construction. Thus, the establishment of the finite element model is completed.

[0039] Afterwards Figure 7 As shown in the figure, the changes in the surface settlement of the site in each year after the project was put into use are calculated. The surface settlement curve is specifically simulated when the site is completely consolidated after construction (about 11.3 years after construction). It can be seen from the figure that the main settlement occurs in the mixing pile area, and the closer the pre-compression area is to the mixing pile area, the greater the settlement.

[0040] Afterwards Figure 8 As shown in the figure, for different sites after construction time, the surface slope curve (i.e., the first-order derivative of the settlement curve) shows that the area with a larger slope is outside the boundary of the foundation treatment. As the time after construction increases, the range continues to expand, with a maximum of about 13m (this is also the main coordinated treatment range); in addition, the maximum surface slope appears 2 to 3m outside the interface. When the soil is completely consolidated, the maximum value is slightly less than 5‰ (i.e., the coordination measure selection time point can be taken at the final moment).

[0041] Finally, according to the bottom surface material and slope required by the table 5.4.1 of the "Sports Building Design Code" for football field specifications, the natural lawn is ≤5 / 1000. This shows that the original design slope of less than 5‰ meets the requirements for football field use. In addition, according to Tang Donghua and Chen Haibo. Numerical analysis of post-construction settlement of transition sections of different foundation treatments, the original design of less than 5‰ also meets the requirements for road use.

[0042] In summary, the estimated long-term differential settlement of the foundation treatment interface area under the design parameters meets the specifications and relevant use requirements, and the construction drawings can be directly drawn according to the design parameters.

[0043] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A foundation treatment design method considering coordinated deformation control at the interface of different treatment forms, characterized by: The steps include: Step 1: Carry out the corresponding foundation treatment design according to different foundation treatment forms in accordance with the current specifications and obtain the foundation design parameters; Step 2: According to the foundation design parameters and the stratum distribution in the geological survey report, a PLAXIS finite element model of the boundary area of ​​the foundation treatment form is constructed, and the model stratum parameters are calibrated using the geotechnical test parameters in the geological survey report; Step 3: Based on the finite element model in step 2, calculate the change of the site surface settlement in each year after the project is put into use. Derivative the ground settlement with respect to the horizontal distance to obtain the change of the site surface slope in each year; Step 4: Substitute the surface slope S of the site in each year in step 3 d Changes and current standard verification slope limit values ​​[S d ] to confirm the surface slope S of the site in each year. d Whether it exceeds the standard calibration slope limit [S d ]; if the surface slope S of the site in each year d Does not exceed the standard verification slope limit [S d ], it means that the design parameters of step 1 meet the requirements, and there is no need to increase or adjust the settlement control measures of the boundary area. The construction drawings are drawn according to the foundation design parameters; Step 5: For example, the surface slope change S of the site in each year d Exceeding the standard calibration slope limit [S d ], for the areas with excessive slope around the boundaries of different foundation treatment forms, add differential settlement control measures or / and adjust the existing differential settlement control measures to form new foundation design parameters and return to step 2.

2. A foundation treatment design method considering coordinated deformation control of interface areas of different treatment forms according to claim 1, characterized in that: In step 2.

3. A foundation treatment design method considering coordinated deformation control of interface areas of different treatment forms according to claim 1, characterized in that: The specific algorithm for the change of the site surface slope in each year in step 3 is: the change of the site surface settlement S with the horizontal position x in each year, that is, S = f(x). The surface slope S of the site in each year can be obtained by taking the derivative of the ground settlement S with respect to the horizontal position x. d With the change of horizontal position, that is: S d =f′(x).

4. A foundation treatment design method considering coordinated deformation control of interface areas of different treatment forms according to claim 1, characterized in that: The standard check slope limit value in step 4 [S d ]Select according to the specifications corresponding to different partitions.

5. A foundation treatment design method considering coordinated deformation control of interface areas of different treatment forms according to claim 1, characterized in that: Step 5: The differential settlement of some areas at horizontal position x∈(a,b) exceeds the limit, and the surface slope S of the site in each year d Exceeding the standard check slope limit [S d ],S d =f′(x)>[S d ],x∈(a,b), then record the exceeded range x∈(a,b); for the area where the slope exceeds the limit, choose to add differential settlement control measures or adjust the existing differential settlement control measures.

6. A foundation treatment design method considering coordinated deformation control of interface areas of different treatment forms according to claim 5, characterized in that: In step 5, adding differential settlement control measures specifically involves extending the treatment range according to the characteristics of the treatment measures, wherein the extended treatment range is an extension length of c, and the distribution range of the treatment measures is the area of ​​the horizontal position x∈(ac,b+c), and adding corresponding treatment measures in the finite element model based on the horizontal position x∈(ac,b+c).

7. A foundation treatment design method considering coordinated deformation control of interface areas of different treatment forms according to claim 5, characterized in that: In step 5, differential settlement control measures include adjusting the pile spacing, geogrid strength and number of tracks, and frame thickness.

8. A foundation treatment design method considering coordinated deformation control of interface areas of different treatment forms according to claim 5, characterized in that: In step 5, differential settlement control measures are added and / or adjusted based on the construction period, cost and treatment effect.

9. A foundation treatment design method considering coordinated deformation control of interface areas of different treatment forms according to claim 6, characterized in that: In step 5, if there is an over-limit or there is no over-limit but the cost of the measures is too high, the design parameters of the differential settlement control measures can be adjusted, including the pile spacing, geogrid strength and number of tracks, and frame thickness, and the finite element model parameters can be modified for recalculation and verification.

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