Pile foundation side friction and exertion coefficient calculation method and device considering interface shape

Abstract

The invention relates to the technical field of pile foundation side frictional resistance calculation, in particular to a pile foundation side frictional resistance and exertion coefficient calculation method and device considering the interface shape, and the method comprises the steps: obtaining a hole shape graph of a hole wall of a drilled hole, and extracting a hole wall curve corresponding to the hole shape graph; the interface shapes of the hole wall curve are classified, and the length proportions of all kinds of interface shapes in the hole wall curve are counted; performing a shear test corresponding to each type of interface shape to obtain shear strength corresponding to each type of interface shape; and according to the length proportions and the shear strength of the various interface shapes, calculating the pile foundation side frictional resistance f of the bored pile. According to the method, the accurate side friction resistance and the side friction resistance exerting coefficient can be obtained.

Description

Technical Field

[0001] The invention relates to the technical field of pile foundation lateral friction calculation, and in particular to a method and device for calculating pile foundation lateral friction and its exertion coefficient taking interface shape into consideration. Background Art

[0002] The side friction coefficient is one of the important parameters in the design of rock-embedded piles. When calculating the characteristic value of the axial compressive bearing capacity of a single pile, the side friction coefficient is required to calculate the pile side bearing capacity. The relationship between the side friction and the coefficient is: f = c2f rk , where c2 is the coefficient of lateral friction, f is the lateral friction of the pile in the rock-embedded section of the pile foundation, i.e., the shear strength of the pile-rock interface, and f rk is the saturated uniaxial compressive strength of the rock on the pile side, that is, the side friction coefficient c2 is the ratio of the pile-rock interface shear strength to the saturated uniaxial compressive strength of the rock. The pile-rock interface shear strength can be obtained through direct shear tests.

[0003] In the relevant specifications, the value range of the side friction coefficient is 0.03-0.05, which is the value method for terrestrial rocks with relatively uniform texture. However, for heterogeneous rock formations, such as reef limestone, it is the main component of marine island geology. Because reef limestone is a sedimentary rock formed by seabed biocementation, there are uneven pores inside the rock mass. Brittleness, porosity and heterogeneity are the most typical characteristics of reef limestone, which is also one of the biggest differences from terrestrial rocks. When pile foundation drilling is carried out in heterogeneous rock formations, the hole wall is also non-uniform and irregular, resulting in a great difference between the interface between the pile foundation and the rock formation and the homogeneous rock formation after the pile foundation is poured, which makes the value of the side friction coefficient also very different. It is inaccurate to calculate the side friction according to the value of the specification. Therefore, a method is needed to determine the side friction and coefficient of cast-in-place piles in heterogeneous rock formations, so as to optimize the pile foundation design method, enhance the safety of the pile foundation and save costs. Summary of the invention

[0004] The purpose of the present invention is to address the defects of the prior art and provide a method and device for calculating the lateral friction resistance and the exertion coefficient of pile foundation taking into account the interface shape, so as to obtain more accurate lateral friction resistance and the exertion coefficient of lateral friction resistance.

[0005] In order to solve the above technical problems, the present invention provides a method for calculating the lateral friction resistance of pile foundation considering the interface shape, comprising:

[0006] Obtaining a hole shape diagram of a drilled hole wall and extracting a hole wall curve corresponding to the hole shape diagram;

[0007] Classify the interface shapes of the hole wall curve and count the length proportions of various interface shapes in the hole wall curve;

[0008] Conduct a shear test corresponding to each type of interface shape to obtain the shear strength corresponding to each type of interface shape;

[0009] The side friction f of the bored pile foundation is calculated based on the length proportion and shear strength of various interface shapes.

[0010] Furthermore, the method for obtaining a hole shape diagram of a borehole wall and extracting a hole wall curve corresponding to the hole shape diagram includes: using an ultrasonic hole forming quality detector to measure the hole shape diagram of the borehole wall along the x-direction and the y-direction, wherein the x-direction is perpendicular to the y-direction, and the planes where the x-direction and the y-direction are located are perpendicular to the axial direction of the borehole; and extracting two hole wall curves characterizing the hole wall morphology from each hole shape diagram.

[0011] Furthermore, the interface shapes include seven types, namely, smooth plane, bevel serration, step serration, outer arc serration, outer V serration, inner arc serration and inner V serration;

[0012] The hole wall curve is classified according to the above seven interface shapes, and the length proportion of each interface shape in the hole wall curve is counted.

[0013] Furthermore, the method of classifying the hole wall curve according to the above seven interface shapes includes:

[0014] The hole wall curve is segmented with b as the unit length to form multiple hole wall segmented curves, the multiple hole wall segmented curves are input into a preset network model, and the interface shape corresponding to each hole wall segmented curve is output.

[0015] Furthermore, the method for counting the length proportions of various interface shapes in the hole wall curve includes: counting the length proportions of each interface shape in each hole wall curve, summing up the length proportions of the same interface shapes in all hole wall curves and calculating the average value, which is the length proportions of various interface shapes corresponding to the drill hole.

[0016] Further, the shear test includes:

[0017] Core sampling is performed to make n shear specimens, where n is the number of types of interface shapes included in the hole wall curve, n≤7. The shear specimen includes an upper half and a lower half. The upper half is a heterogeneous rock sample, and the lower half is a concrete sample. The interface shape between the two is made according to the various interface shapes corresponding to the hole wall curve. The interface filling form between the upper half and the lower half of the shear specimen is set according to the type of pile foundation.

[0018] The shear test was carried out on the shear specimens to obtain the shear strengths f1, f2, ..., f corresponding to various interface shapes. n .

[0019] Furthermore, the interface filling forms between the upper and lower halves of the shear specimen include casting, post-grouting, no filling, and mud surface filling.

[0020] Furthermore, the preparation methods of shear specimens corresponding to the interface filling forms of pouring, post-grouting, no filling and mud surface filling are:

[0021] Casting: placing the heterogeneous rock sample on the undried concrete sample, and obtaining the shear specimen after curing;

[0022] Post-grouting: After the heterogeneous rock sample and the dried concrete sample are fitted together, cement slurry is injected into the gap between them, and the shear specimen is obtained after curing;

[0023] No filling: The shear specimen can be obtained by directly fitting the heterogeneous rock sample and the dried concrete sample;

[0024] Mud surface filling: Apply cement slurry on the surface of the heterogeneous rock sample, fit it with the dried concrete sample and press it tightly, and then obtain the shear specimen after curing.

[0025] Further, calculate the pile foundation side friction f = f1×a1+f2×a2+...+f n ×a n , where a n Indicates the length ratio of the nth type of interface shape.

[0026] In a second aspect, the present invention provides a method for calculating the lateral friction coefficient of a pile foundation taking into account the interface shape, comprising:

[0027] The saturated uniaxial compression test of rock samples was carried out to obtain the saturated uniaxial compressive strength f of the rock on the pile side. rk ;

[0028] Calculate the side friction coefficient c2 = f / f rk .

[0029] In a third aspect, the present invention provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method for calculating the side friction resistance of a pile foundation taking into account the interface shape, and the steps of the method for calculating the utilization coefficient.

[0030] In a fourth aspect, the present invention provides a computer program product, comprising a computer program / instruction, which, when executed by a processor, implements the steps of the method for calculating the side friction resistance of a pile foundation taking into account the interface shape, and the steps of the method for calculating the utilization coefficient.

[0031] The beneficial effects of the present invention are:

[0032] 1. The present invention divides the interface shapes into seven types, designs shear tests according to different cross-sectional shapes, and calculates the lateral friction resistance of the pile foundation in the heterogeneous rock formation, thereby obtaining a more accurate lateral friction resistance coefficient, which can solve the problem that the value of the lateral friction resistance coefficient in the specification is not accurate enough.

[0033] 2. The present invention can guide the optimization of pile foundation design by accurately calculating the lateral friction resistance coefficient, thereby enhancing the safety of the pile foundation and saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The hole wall curve diagram extracted from the hole shape diagram along the x-direction and the y-direction in Example 1 of the present invention;

[0035] Figure 2 The diagram is a shear specimen model diagram of seven interface shapes of the present invention;

[0036] Figure 3 These are experimental diagrams of shear specimens with seven interface shapes according to the present invention. DETAILED DESCRIPTION

[0037] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0038] Example 1

[0039] This embodiment provides a method for calculating the lateral friction of a pile foundation taking into account the interface shape, including:

[0040] Step 1: Obtain the hole shape diagram of the borehole wall and extract the hole wall curve corresponding to the hole shape diagram. According to Article 4.1 and 4.3.3 of the Technical Regulations for Pile Testing of Highway Engineering, it is generally assumed that the pile hole is a standard circle, ignoring the deviation caused by the irregularity of the hole diameter roundness; use the ultrasonic hole-forming diagram in two orthogonal directions to characterize the hole shape.

[0041] Step 1 specifically includes:

[0042] The hole shape diagram of the borehole wall along the x-direction and the y-direction is measured using an ultrasonic hole quality detector, where the x-direction is perpendicular to the y-direction, and the plane where the x-direction and the y-direction are located is perpendicular to the axial direction of the borehole; two hole wall curves representing the hole wall morphology are extracted from each hole shape diagram, and data preprocessing is performed, that is, noise is removed and data smoothing is performed to obtain the following: Figure 1 The hole wall curve is shown.

[0043] Step 2: classify the interface shapes of the hole wall curve, and count the length proportions of various interface shapes in the hole wall curve; Step 2 specifically includes:

[0044] There are seven interface shapes: smooth plane, bevel serration, step serration, outer arc serration, outer V serration, inner arc serration and inner V serration. Figure 2 As shown;

[0045] Each hole wall curve is segmented with b=1m as the unit length to form multiple hole wall segmented curves, and the multiple hole wall segmented curves are input into the preset network model, and the interface shape corresponding to each hole wall segmented curve is output. In this embodiment, all hole wall segmented curves can be divided into seven types, and the length proportions of the seven interface shapes corresponding to the four hole wall curves are calculated. The length proportions of the same interface shapes in the four hole wall curves are summed and the average value is calculated to obtain the length proportions of the seven interface shapes corresponding to the drilling. The length proportions corresponding to the seven interface shapes are shown in Table 1.

[0046] Table 1

[0047]

[0048]

[0049] In this embodiment, the network model adopts the SVM split network model, and the method for establishing the network model includes:

[0050] Collect historical data: collect enough (e.g. 1,000) borehole wall curves;

[0051] Data segmentation: The collected hole wall curve is segmented with a unit length of 1m in the pile depth direction to form hole shape data with a unit length of 1m;

[0052] Segmentation data normalization: normalize the hole shape data with a unit length of 1m. Among them, X e is the original eigenvalue, X min To select the smallest eigenvalue in this unit length, X max To select the eigenvalue with the largest value in this unit length, is the normalized value of the eigenvalue;

[0053] Labeling: Classify and label the historical data, and divide the historical data into seven interface shapes: smooth plane, bevel sawtooth, step sawtooth, outer arc sawtooth, outer V sawtooth, inner arc sawtooth and inner V sawtooth, forming a historical data set;

[0054] Deep learning network, establish SVM network model: use historical data sets to perform sample training and test samples, and establish SVM split network model. The establishment of this SVM split network model belongs to the prior art.

[0055] Step 3: Conduct a shear test corresponding to each type of interface shape to obtain the shear strength corresponding to each type of interface shape; Step 3 specifically includes:

[0056] At the project site, core samples were taken from the rock formation and seven shear specimens were prepared, such as Figure 2 , 3 As shown, the shear specimen includes an upper part and a lower part. The upper part is a non-homogeneous rock sample, and the lower part is a concrete sample. The interface shape between the two is made according to various interface shapes corresponding to the hole wall curve.

[0057] The interface filling form between the upper and lower parts of the shear specimen is set according to the type of pile foundation. The interface filling forms include pouring, post-grouting, no filling and mud surface filling. Among them, the interface filling form corresponding to the overall pouring of piles after clear water drilling is pouring; the interface filling form corresponding to the cement slurry after directly driving the pile is post-grouting; the interface filling form corresponding to the directly driven pile is no filling; the interface filling form corresponding to the mud wall bored pile is mud surface filling.

[0058] The preparation methods of shear specimens corresponding to the interface filling forms of pouring, post-grouting, no filling and mud surface filling are:

[0059] Casting: placing the heterogeneous rock sample on the undried concrete sample, and obtaining the shear specimen after curing;

[0060] Post-grouting: After the heterogeneous rock sample and the dried concrete sample are fitted together, cement slurry is injected into the gap between them, and the shear specimen is obtained after curing;

[0061] No filling: The shear specimen can be obtained by directly fitting the heterogeneous rock sample and the dried concrete sample;

[0062] Mud surface filling: Apply cement slurry on the surface of the heterogeneous rock sample, fit it with the dried concrete sample and press it tightly, and then obtain the shear specimen after curing.

[0063] The pile foundation in this embodiment is a bored cast-in-place pile, and the interface filling form is casting.

[0064] The shear test was carried out on the shear specimens to obtain the shear strengths f1, f2, ..., f corresponding to various interface shapes. n , as shown in Table 2.

[0065] Table 2

[0066]

[0067]

[0068] Step 4: Calculate the side friction resistance of the bored pile foundation based on the length ratio and shear strength of various interface shapes: f = f1×a1+f2×a2+...+f n ×a n , where a n Indicates the length proportion of the nth type of interface shape,

[0069] f=17%×3.0+13%×2.7+12%×3.2+16%×2.3+14%×2.0+15%×1.4+13%×2.9=2.48MPa.

[0070] Example 2

[0071] Based on Example 1, this embodiment provides a method for calculating the friction coefficient of the pile foundation side considering the interface shape, including step 5: performing a saturated uniaxial compression test on a rock sample to obtain the saturated uniaxial compressive strength f of the rock on the pile side. rk =6.2MPa, calculate the side friction coefficient c2 = f / f rk =0.4.

[0072] In Article 6.3.7 of the "Code for Design of Foundations and Subgrades for Highway Bridges and Culverts", for the method of selecting values ​​for terrestrial rocks with relatively uniform texture, the value range of the side friction coefficient c2 is 0.03-0.05, while the side friction coefficient of inhomogeneous rock layers (such as reef limestone) obtained through experiments is 0.4, which is ten times the value specified in the code. Therefore, the value of the side friction coefficient has a great influence on the design of the bearing capacity of the pile foundation. Calculating the side friction coefficient according to the method of the present invention can guide the optimization of pile foundation design.

[0073] Example 3

[0074] This embodiment provides a non-transitory computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of the method for calculating the pile foundation side friction resistance considering the interface shape in Embodiment 1 and the steps of the method for calculating the performance coefficient in Embodiment 2 are implemented.

[0075] Example 4

[0076] This embodiment provides a computer program product, including a computer program / instruction, which, when executed by a processor, implements the steps of the method for calculating the side friction resistance of the pile foundation considering the interface shape in Example 1 and the steps of the method for calculating the performance coefficient in Example 2.

[0077] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for calculating the lateral friction of pile foundation taking into account the interface shape, characterized in that: include: Obtaining a hole shape diagram of a drilled hole wall and extracting a hole wall curve corresponding to the hole shape diagram; Classify the interface shapes of the hole wall curve and count the length proportions of various interface shapes in the hole wall curve; Conduct a shear test corresponding to each type of interface shape to obtain the shear strength corresponding to each type of interface shape; The side friction f of the bored pile foundation is calculated based on the length proportion and shear strength of various interface shapes.

2. The method for calculating the pile foundation side friction resistance considering the interface shape according to claim 1 is characterized in that: The method for obtaining a hole shape diagram of a borehole wall and extracting a hole wall curve corresponding to the hole shape diagram comprises: using an ultrasonic hole forming quality detector to measure the hole shape diagram of the borehole wall along the x-direction and the y-direction, wherein the x-direction is perpendicular to the y-direction, and the plane where the x-direction and the y-direction are located is perpendicular to the axial direction of the borehole; and extracting two hole wall curves representing the hole wall morphology from each hole shape diagram.

3. The method for calculating the pile foundation side friction resistance considering the interface shape according to claim 1 is characterized in that: The interface shapes include smooth plane, bevel serration, step serration, outer arc serration, outer V serration, inner arc serration and inner V serration; The hole wall curve is classified according to the above seven interface shapes, and the length proportion of each interface shape in the hole wall curve is counted.

4. The method for calculating the pile foundation side friction resistance considering the interface shape according to claim 3 is characterized in that: The methods for classifying the hole wall curve according to the above seven interface shapes include: The hole wall curve is segmented with b as the unit length to form multiple hole wall segmented curves, the multiple hole wall segmented curves are input into a preset network model, and the interface shape corresponding to each hole wall segmented curve is output.

5. The method for calculating the pile foundation side friction resistance considering the interface shape according to claim 4 is characterized in that: The method for counting the length proportions of various interface shapes in the hole wall curve includes: counting the length proportions of each interface shape in each hole wall curve, summing up the length proportions of the same interface shape in all hole wall curves and calculating the average value, which is the length proportions of various interface shapes corresponding to the drill hole.

6. The method for calculating the pile foundation side friction resistance considering the interface shape according to claim 1 is characterized in that: Shear tests include: Core sampling is performed to make n shear specimens, where n is the number of types of interface shapes included in the hole wall curve, n≤7. The shear specimen includes an upper half and a lower half. The upper half is a heterogeneous rock sample, and the lower half is a concrete sample. The interface shape between the two is made according to the various interface shapes corresponding to the hole wall curve. The interface filling form between the upper half and the lower half of the shear specimen is set according to the type of pile foundation. The shear test was carried out on the shear specimens to obtain the shear strengths f1, f2, ..., f corresponding to various interface shapes. n .

7. The method for calculating the lateral friction of pile foundation considering the interface shape according to claim 6 is characterized in that: The filling forms of the interface between the upper and lower parts of the shear specimen include casting, post-grouting, no filling and mud surface filling.

8. The method for calculating the pile foundation side friction resistance considering the interface shape according to claim 7 is characterized in that: The preparation methods of shear specimens corresponding to the interface filling forms of pouring, post-grouting, no filling and mud surface filling are: Casting: placing the heterogeneous rock sample on the undried concrete sample, and obtaining the shear specimen after curing; Post-grouting: After the heterogeneous rock sample and the dried concrete sample are fitted together, cement slurry is injected into the gap between them, and the shear specimen is obtained after curing; No filling: The shear specimen can be obtained by directly fitting the heterogeneous rock sample and the dried concrete sample; Mud surface filling: Apply cement slurry on the surface of the heterogeneous rock sample, fit it with the dried concrete sample and press it tightly, and then obtain the shear specimen after curing.

9. The method for calculating the lateral friction of pile foundation considering the interface shape according to claim 6, characterized in that: Calculate the lateral friction resistance of pile foundation f = f1×a1+f2×a2+...+f n ×a n , where a n Indicates the length ratio of the nth type of interface shape.

10. A method for calculating the utilization coefficient of the method for calculating the pile foundation lateral friction resistance taking into account the interface shape according to any one of claims 1 to 9, characterized in that: include: The saturated uniaxial compression test of rock samples was carried out to obtain the saturated uniaxial compressive strength f of the rock on the pile side. rk ; Calculate the side friction coefficient c2 = f / f rk .

11. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for calculating the pile foundation side friction resistance taking into account the interface shape as described in any one of claims 1 to 9 and the steps of the method for calculating the performance coefficient as described in claim 10 are implemented.

12. A computer program product comprising a computer program / instructions, characterized in that: When the computer program / instructions are executed by a processor, the steps of the method for calculating the pile foundation side friction resistance taking into account the interface shape as described in any one of claims 1 to 9 and the steps of the method for calculating the performance coefficient as described in claim 10 are implemented.

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