Method and system for judging reliability of pile end bearing stratum of punching cast-in-place pile

Abstract

The invention relates to the technical field of geotechnical engineering, in particular to a method and a system for judging the reliability of a pile end bearing stratum of a punching cast-in-place pile. Obtaining effective thickness information, penetration information and punching time consumption information of each stroke section after the pile well is tunneled to the elevation range of the designed bearing stratum, peripheral ground surface settlement information of the pile well, in-well mud information, well bottom flatness information and well wall inclination information; evaluating a plurality of judgment indexes of the bearing stratum of the pile end according to the information; and finally, according to the evaluation result of each judgment index, judging whether the pile end bearing stratum is reliable or not. Wherein the multiple judgment indexes comprise the seven indexes of ground surface settlement, well bottom flatness, well wall inclination, integrity of a pile end bearing layer, continuous stability of the pile end bearing layer, rock strength of the pile end bearing layer and effective thickness.

Description

Technical Field

[0001] The invention relates to the technical field of geotechnical engineering, and in particular to a method and system for determining the reliability of a bearing layer at a pile end of a bored cast-in-place pile. Background Art

[0002] Bored pile projects in areas with complex underground karst development are often difficult to accurately judge the reliability of the bearing layer at the pile end due to the high degree of karstification, difficulty in dealing with geological defects, and difficulty in grasping the effective bearing layer. Misjudgment and wrong judgment of the reliability of the bearing layer at the pile end can easily cause the failure of the deep pile foundation project, thereby causing significant economic losses to the project construction, project quality and operational safety problems, and even some adverse natural environmental hazards.

[0003] In order to solve the above problems, the existing methods for judging the reliability of the bearing layer at the end of bored cast-in-place piles usually evaluate the continuous stability and integrity of the bearing layer at the end of the bored cast-in-place piles (usually the evaluation basis is obtained by detecting the karst development status of the bearing layer at the end of the piles), and judge the reliability of the bearing layer at the end of the piles according to the evaluation results. However, since the existing methods for judging the reliability of the bearing layer at the end of bored cast-in-place piles usually do not comprehensively evaluate the mechanical characteristics of the bearing layer at the end of the piles (such as but not limited to: the rock strength of the bearing layer at the end of the piles) and the construction factors of the pile well excavation (such as but not limited to: the surface settlement caused by the pile well construction, the flatness of the bottom of the pile well, the inclination of the well wall, and the effective thickness of the part of the pile well entering the elevation range of the designed bearing layer) on the reliability of the bearing layer at the end of the piles, the existing methods for judging the reliability of the bearing layer at the end of bored cast-in-place piles still have the problem of being difficult to accurately judge the reliability of the bearing layer at the end of the piles, which is easy to cause the failure of the deep pile foundation project, thereby causing significant economic losses to the project construction, project quality and operation safety problems, and even some technical problems of adverse natural environmental hazards. Summary of the invention

[0004] The present invention provides a method and system for determining the reliability of the bearing layer at the end of a bored cast-in-place pile, thereby solving the problem that the existing method for determining the reliability of the bearing layer at the end of a bored cast-in-place pile usually fails to comprehensively evaluate the influence of the mechanical characteristics of the bearing layer at the end of the pile and the construction factors of the pile well excavation on the reliability of the bearing layer at the end of the pile, so that the existing method for determining the reliability of the bearing layer at the end of a bored cast-in-place pile still has the problem of being difficult to accurately determine the reliability of the bearing layer at the end of the pile, which easily causes failure of the deep pile foundation project, thereby causing major economic losses to the project construction, problems with the project quality and operational safety, and even technical problems of harming some adverse natural environments.

[0005] The technical solution adopted by the present invention is:

[0006] A method for determining the reliability of the bearing layer at the end of a bored pile, comprising:

[0007] After the pile well is excavated to the elevation range of the designed bearing layer, effective thickness information, penetration information and punching time information of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer, surrounding surface settlement information of the pile well, mud information in the well, well bottom flatness information and well wall inclination information are obtained;

[0008] Evaluate multiple determination indicators of the pile end bearing layer according to the effective thickness information, the penetration information, the punching time information, the hammer wear information, the surrounding surface settlement information, the mud information in the well, the well bottom flatness information and the well wall inclination information;

[0009] According to the evaluation results of various determination indicators, whether the bearing layer at the pile end is reliable is determined;

[0010] The multiple judgment indicators include seven indicators: surface settlement, well bottom flatness, well wall inclination, integrity of pile end bearing layer, continuous stability of pile end bearing layer, rock strength of pile end bearing layer, and effective thickness.

[0011] The method for determining the reliability of the bearing layer at the end of a bored cast-in-place pile provided by the present invention utilizes the effective thickness information, the penetration information, the punching time information, the hammer wear information, the surrounding surface settlement information, the mud information in the well, the well bottom flatness information and the well wall inclination information to evaluate seven indicators of the bearing layer at the end of the pile. The method can comprehensively evaluate the integrity of the bearing layer at the end of the pile, the continuous stability of the bearing layer at the end of the pile, the mechanical characteristics of the bearing layer at the end of the pile (by evaluating the rock strength of the bearing layer at the end of the pile) and the construction factors of pile well excavation (by evaluating the four indicators of surface settlement, well bottom flatness, well wall inclination and effective thickness), and can effectively improve the accuracy of determining the reliability of the bearing layer at the end of the pile, thereby avoiding the failure of deep pile foundation engineering.

[0012] Furthermore, if the evaluation results of the determination indicators are all qualified, the pile end bearing layer is determined to be reliable; if the evaluation result of any one of the determination indicators is unqualified, the pile end bearing layer is determined to be unreliable.

[0013] Furthermore, the method for evaluating the integrity of the pile end bearing layer includes:

[0014] According to the mud information in the well, the first well mud level height change value corresponding to each construction interval period after the pile well is excavated to the elevation range of the designed bearing layer is obtained, and the second well mud level height change value within the first preset time range after the pile well excavation construction is completed is obtained;

[0015] evaluating the integrity of the pile end bearing layer according to the obtained value of the change in the mud level in the first well and the value of the change in the mud level in the second well;

[0016] If the change values ​​of the mud level height in each of the first wells are less than the first preset height change value, and the change value of the mud level height in the second well is less than the second preset height change value, then the evaluation result of the integrity of the bearing layer at the pile end is qualified; otherwise, the evaluation result of the integrity of the bearing layer at the pile end is unqualified.

[0017] By obtaining the mud level height change value in the first well corresponding to each construction interval period after the pile well is excavated to the elevation range of the designed bearing layer, and the mud level height change value in the second well within the first preset time range after the pile well excavation construction is completed; the permeability of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer can be obtained through the mud level height change value in the second well and the mud level height change value in each first well, so as to provide a judgment basis for judging the integrity of the bearing layer at the pile end.

[0018] Furthermore, the method for evaluating the continuous stability of the pile end bearing layer includes:

[0019] According to the penetration information and the punching time information, the first average penetration and punching time of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer are obtained;

[0020] The continuous stability of the pile end bearing layer is evaluated according to the obtained first average penetration and punching time value of each stroke section;

[0021] If the difference between the first average penetration rates of any two adjacent stroke segments is less than a first preset difference, and the difference between the punching times of any two adjacent stroke segments is less than a second preset difference, then the evaluation result of the continuous stability of the pile end bearing layer is qualified; otherwise, the evaluation result of the continuous stability of the pile end bearing layer is unqualified.

[0022] By obtaining the difference between the first average penetration of any two adjacent stroke sections after the pile well is excavated to the elevation range of the designed bearing layer and the difference between the punching time of any two adjacent stroke sections, a basis for judging the continuous stability of the bearing layer at the pile end can be provided.

[0023] Furthermore, after the pile well is excavated to the elevation range of the designed bearing layer, the sample slag information of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer is also obtained;

[0024] The continuous stability of the pile end bearing layer is a determination index including punching consistency and continuous stability of sample slag. The method for evaluating the continuous stability of the pile end bearing layer includes:

[0025] The punching consistency is evaluated according to the penetration information and the punching time information, and the continuous stability of the sample slag is evaluated according to the sample slag information;

[0026] If the evaluation results of the two judgment sub-indicators of the punching consistency and the continuous stability of the sample slag are both qualified, the evaluation result of the continuous stability of the pile end bearing layer is qualified; otherwise, the evaluation result of the continuous stability of the pile end bearing layer is unqualified.

[0027] By making the continuous stability of the pile end bearing layer a judgment indicator including two judgment sub-indicators, namely, punching consistency and continuous stability of sample slag; and by comprehensively evaluating the continuous stability of sample slag and punching consistency to evaluate the continuous stability of the pile end bearing layer, the judgment accuracy of the continuous stability of the pile end bearing layer can be effectively improved compared with the method of evaluating the continuous stability of the pile end bearing layer based solely on the evaluation results of punching consistency or continuous stability of sample slag.

[0028] Furthermore, the method for evaluating the surface subsidence includes:

[0029] According to the surrounding surface settlement information, the maximum surface settlement value around the pile well during the entire process of pile well excavation construction is obtained;

[0030] Evaluating the surface settlement according to the maximum surface settlement value of the surrounding area;

[0031] If the maximum surface settlement value of the surrounding area is less than the preset surface settlement value, the evaluation result of the surface settlement is qualified; otherwise, the evaluation result of the surface settlement is unqualified.

[0032] Furthermore, the method for evaluating the rock strength of the pile end bearing layer includes:

[0033] Acquire a first mapping relationship between a second average penetration rate during the excavation process of a standard stroke section and a first compressive strength value of the standard stroke section;

[0034] According to the penetration information, a first average penetration of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer is obtained;

[0035] Obtaining a second compressive strength value of each stroke segment according to the obtained first mapping relationship and the first average penetration of each stroke segment, and evaluating the rock strength of the pile end bearing layer according to the obtained second compressive strength value of each stroke segment;

[0036] If the second compressive strength value of each stroke segment is not less than the preset compressive strength value, the evaluation result of the rock strength of the pile end bearing layer is qualified; otherwise, the evaluation result of the rock strength of the pile end bearing layer is unqualified.

[0037] The first mapping relationship may be obtained in a variety of ways, such as but not limited to: the first mapping relationship is obtained through a standard penetration test.

[0038] Furthermore, after the pile well is excavated to the elevation range of the designed bearing layer, the hammer wear information of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer is also obtained;

[0039] The method for evaluating the rock strength of the pile end bearing layer includes:

[0040] Acquire a first mapping relationship between a second average penetration rate during the excavation process of a standard stroke section and a first compressive strength value of the standard stroke section;

[0041] Acquire a second mapping relationship between a first hammer claw wear ratio value during excavation of a standard stroke section and a first compressive strength value of the standard stroke section;

[0042] According to the penetration information, a first average penetration of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer is obtained;

[0043] According to the hammer wear information, the second hammer claw wear ratio value of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer is obtained;

[0044] According to the obtained first mapping relationship and the first average penetration of each stroke segment, a second compressive strength value of each stroke segment is obtained; according to the obtained second mapping relationship and the second hammer claw wear ratio value of each stroke segment, a third compressive strength value of each stroke segment is obtained; according to the obtained second compressive strength value and third compressive strength value of each stroke segment, the rock strength of the pile end bearing layer is evaluated;

[0045] If the second compressive strength value and the third compressive strength value of each stroke segment are not less than the preset compressive strength value, the evaluation result of the rock strength of the pile end bearing layer is qualified; otherwise, the evaluation result of the rock strength of the pile end bearing layer is unqualified.

[0046] The second mapping relationship can be obtained in a variety of ways, such as but not limited to: obtaining the second mapping relationship through comparative tests, obtaining the second mapping relationship by analyzing historical data of the same model of punching pile drivers, and calculating the second mapping relationship through the empirical coefficient between the hammer wear ratio and the rock compressive strength.

[0047] Furthermore, the method for evaluating the well bottom flatness includes:

[0048] According to the well bottom flatness information, the well bottom flatness value of the pile well after the pile well excavation construction is completed is obtained.

[0049] Evaluating the well bottom flatness according to the obtained well bottom flatness value;

[0050] If the well bottom flatness value is not greater than the preset flatness value, the evaluation result of the well bottom flatness is qualified, otherwise the evaluation result of the well bottom flatness is unqualified.

[0051] Furthermore, the method for evaluating the wellbore inclination includes:

[0052] According to the well wall inclination information, the well wall inclination value of the pile well after the pile well excavation construction is completed is obtained.

[0053] Evaluating the well wall inclination according to the obtained well wall inclination value;

[0054] If the well wall inclination value is not greater than the preset inclination value, the evaluation result of the well wall inclination is qualified; otherwise, the evaluation result of the well wall inclination is unqualified.

[0055] Further, the method for evaluating the effective thickness includes:

[0056] According to the effective thickness information, the effective thickness value of the portion of the pile well within the elevation range of the designed bearing layer after the pile well excavation construction is completed is obtained;

[0057] evaluating the effective thickness according to the obtained effective thickness value;

[0058] If the effective thickness value is not less than the preset thickness value, the evaluation result of the effective thickness is qualified; otherwise, the evaluation result of the effective thickness is unqualified.

[0059] According to the method for determining the reliability of the bearing layer at the end of a bored cast-in-place pile provided by the present invention, the present invention also provides a system for determining the reliability of the bearing layer at the end of a bored cast-in-place pile, comprising an acquisition module, an evaluation module and a judgment module.

[0060] The acquisition module is used to obtain effective thickness information, penetration information and punching time information of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer, surrounding surface settlement information of the pile well, mud information in the well, well bottom flatness information and well wall inclination information after the pile well is excavated to the elevation range of the designed bearing layer; and send the obtained effective thickness information, penetration information, punching time information, hammer wear information, surrounding surface settlement information, mud information in the well, well bottom flatness information and well wall inclination information to the evaluation module;

[0061] The evaluation module is used to evaluate multiple determination indicators of the pile end bearing layer according to the obtained effective thickness information, penetration information, punching time information, hammer wear information, surrounding surface settlement information, mud information in the well, well bottom flatness information and well wall inclination information, and send the evaluation results of each determination indicator to the judgment module;

[0062] The judgment module is used to judge whether the pile end bearing layer is reliable according to the evaluation results of various judgment indicators. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 1 is a schematic flow chart of a method for determining the reliability of the bearing layer at the end of a bored pile in Example 1;

[0064] Figure 2 is a schematic flow chart of the method for evaluating the integrity of the pile end bearing layer in Example 1;

[0065] Figure 3 is a schematic flow chart of the method for evaluating the continuous stability of the pile end bearing layer in Example 1;

[0066] Figure 4 is a schematic flow chart of the method for evaluating surface subsidence in Example 1;

[0067] Figure 5 is a schematic flow chart of the method for evaluating the rock strength of the pile end bearing layer in Example 1;

[0068] Figure 6 is a schematic flow chart of the method for evaluating the continuous stability of the pile end bearing layer in Example 2;

[0069] Figure 7 is a schematic flow chart of the method for evaluating the rock strength of the pile end bearing layer in Example 3; DETAILED DESCRIPTION

[0070] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention:

[0071] Embodiment 1:

[0072] like Figure 1 As shown, Example 1 provides a method for determining the reliability of the bearing layer at the end of a bored pile, comprising:

[0073] After the pile well is excavated to the elevation range of the designed bearing layer, the effective thickness information, the penetration information and punching time information of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer, the surrounding surface settlement information of the pile well, the mud information in the well, the well bottom flatness information and the well wall inclination information are obtained;

[0074] Evaluate multiple indicators of the pile end bearing layer based on effective thickness information, penetration information, punching time information, hammer wear information, surrounding surface settlement information, well mud information, well bottom flatness information and well wall inclination information;

[0075] According to the evaluation results of various judgment indicators, judge whether the bearing layer at the pile end is reliable;

[0076] The multiple judgment indicators include surface subsidence, bottom flatness, well wall inclination, integrity of the pile end bearing layer, continuous stability of the pile end bearing layer, rock strength of the pile end bearing layer, and effective thickness.

[0077] The method for determining the reliability of the bearing layer at the pile end of bored cast-in-place piles provided in this embodiment 1 utilizes effective thickness information, penetration information, punching time information, hammer wear information, surrounding surface settlement information, mud information in the well, well bottom flatness information and well wall inclination information to evaluate seven indicators of the bearing layer at the pile end. It can comprehensively evaluate the integrity of the bearing layer at the pile end, the continuous stability of the bearing layer at the pile end, the mechanical characteristics of the bearing layer at the pile end (by evaluating the rock strength of the bearing layer at the pile end) and the construction factors of pile well excavation (by evaluating the four indicators of surface settlement, well bottom flatness, well wall inclination and effective thickness), and can effectively improve the accuracy of determining the reliability of the bearing layer at the pile end and avoid failure of deep pile foundation projects.

[0078] Among them, the specific method of judging whether the bearing layer at the pile end is reliable according to the evaluation results of various judgment indicators can be achieved by using a variety of evaluation methods, including but not limited to:

[0079] Method 1: If the evaluation results of all the judgment indicators are qualified, the pile end bearing layer is judged to be reliable; if the evaluation result of any one of the judgment indicators is unqualified, the pile end bearing layer is judged to be unreliable.

[0080] Method 2: Establish scoring standards for each judgment indicator, and determine whether the bearing layer at the pile end is reliable based on the total score of each judgment indicator.

[0081] Specifically, in this embodiment 1, if the evaluation results of each determination index are qualified, the pile end bearing layer is determined to be reliable; if the evaluation result of any one of the determination indexes is unqualified, the pile end bearing layer is determined to be unreliable.

[0082] In this embodiment 1, Figure 2 As shown in the figure, the methods for evaluating the integrity of the bearing layer at the pile end include:

[0083] According to the mud information in the well, the mud level height change value in the first well corresponding to each construction interval period after the pile well is excavated to the elevation range of the designed bearing layer is obtained, as well as the mud level height change value in the second well within the first preset time range after the pile well excavation construction is completed;

[0084] The integrity of the bearing layer at the pile end is evaluated according to the obtained change value of the mud level in the first well and the change value of the mud level in the second well;

[0085] If the mud level height change values ​​in each first well are less than the first preset height change value, and the mud level height change value in the second well is less than the second preset height change value, then the evaluation result of the integrity of the pile end bearing layer is qualified; otherwise, the evaluation result of the integrity of the pile end bearing layer is unqualified.

[0086] By obtaining the mud level height change value in the first well corresponding to each construction interval period after the pile well is excavated to the elevation range of the designed bearing layer, and the mud level height change value in the second well within the first preset time range after the pile well excavation construction is completed; the permeability of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer can be obtained through the mud level height change value in the second well and the mud level height change values ​​in each first well, so as to provide a judgment basis for judging the integrity of the bearing layer at the pile end.

[0087] In this embodiment 1, Figure 3 As shown in Figure 2, the methods for evaluating the continuous stability of the pile end bearing layer include:

[0088] According to the penetration information and the punching time information, the first average penetration and the punching time of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer are obtained;

[0089] The continuous stability of the pile end bearing layer is evaluated based on the first average penetration and punching time of each stroke section.

[0090] If the difference between the first average penetration rates of any two adjacent stroke segments is less than the first preset difference, and the difference between the punching times of any two adjacent stroke segments is less than the second preset difference, the evaluation result of the continuous stability of the pile end bearing layer is qualified; otherwise, the evaluation result of the continuous stability of the pile end bearing layer is unqualified.

[0091] By obtaining the difference between the first average penetration of any two adjacent stroke sections after the pile well is excavated to the elevation range of the designed bearing layer and the difference between the punching time of any two adjacent stroke sections, a basis for judging the continuous stability of the bearing layer at the pile end can be provided.

[0092] In this embodiment 1, Figure 4 As shown in Figure 2, the methods for evaluating surface subsidence include:

[0093] According to the surrounding surface settlement information, the maximum surface settlement value around the pile well during the entire process of pile well excavation construction is obtained;

[0094] Evaluate the surface settlement based on the maximum surface settlement value of the surrounding area;

[0095] If the maximum surrounding surface settlement value is less than the preset surface settlement value, the evaluation result of the surface settlement is qualified; otherwise, the evaluation result of the surface settlement is unqualified.

[0096] In this embodiment 1, Figure 5 As shown in Figure 2, the methods for evaluating the rock strength of the pile end bearing layer include:

[0097] Acquire a first mapping relationship between a second average penetration rate during the excavation process of the standard stroke section and a first compressive strength value of the standard stroke section;

[0098] According to the penetration information, the first average penetration of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer is obtained;

[0099] According to the obtained first mapping relationship and the first average penetration of each stroke section, the second compressive strength value of each stroke section is obtained, and the rock strength of the pile end bearing layer is evaluated according to the obtained second compressive strength value of each stroke section;

[0100] If the second compressive strength value of each stroke section is not less than the preset compressive strength value, the evaluation result of the rock strength of the pile end bearing layer is qualified, otherwise the evaluation result of the rock strength of the pile end bearing layer is unqualified.

[0101] The first mapping relationship may be obtained in a variety of ways, such as but not limited to: the first mapping relationship is obtained through a standard penetration test.

[0102] The related technologies of standard penetration test belong to the conventional technologies in this professional technical field, so they are not described in detail in the present invention.

[0103] Specifically, in this embodiment 1, the method for evaluating the flatness of the well bottom includes:

[0104] According to the bottom flatness information, the bottom flatness value of the pile well after the pile well excavation construction is completed is obtained.

[0105] According to the obtained well bottom flatness value, the well bottom flatness is evaluated;

[0106] If the well bottom flatness value is not greater than the preset flatness value, the evaluation result of the well bottom flatness is qualified, otherwise the evaluation result of the well bottom flatness is unqualified.

[0107] Specifically, in this embodiment 1, the method for evaluating the wellbore inclination includes:

[0108] According to the inclination information of the well wall, the inclination value of the well wall after the pile well excavation construction is completed is obtained.

[0109] According to the obtained wellbore inclination value, the wellbore inclination is evaluated;

[0110] If the well wall inclination value is not greater than the preset inclination value, the evaluation result of the well wall inclination is qualified, otherwise the evaluation result of the well wall inclination is unqualified.

[0111] Specifically, in this embodiment 1, the method for evaluating the effective thickness includes:

[0112] According to the effective thickness information, the effective thickness value of the part of the pile well within the elevation range of the designed bearing layer after the pile well excavation construction is completed is obtained;

[0113] According to the obtained effective thickness value, the effective thickness is evaluated;

[0114] If the effective thickness value is not less than the preset thickness value, the evaluation result of the effective thickness is qualified, otherwise the evaluation result of the effective thickness is unqualified.

[0115] Embodiment 2:

[0116] Embodiment 2 provides a method for determining the reliability of the bearing layer at the end of a bored cast-in-place pile. The method for determining the reliability of the bearing layer at the end of a bored cast-in-place pile provided in Embodiment 2 is substantially the same as the method for determining the reliability of the bearing layer at the end of a bored cast-in-place pile provided in Embodiment 1. The difference is that, in Embodiment 2, after the pile well is excavated to the elevation range of the designed bearing layer, sample slag information of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer is also obtained;

[0117] The continuous stability of the pile end bearing layer is determined by two sub-indicators: punching consistency and continuous stability of the sample slag. The methods for evaluating the continuous stability of the pile end bearing layer include:

[0118] The punching consistency is evaluated based on the penetration information and the punching time information, and the continuous stability of the sample slag is evaluated based on the sample slag information;

[0119] If the evaluation results of the two judgment sub-indicators of punching consistency and continuous stability of sample slag are both qualified, the evaluation result of the continuous stability of the bearing layer at the pile end is qualified; otherwise, the evaluation result of the continuous stability of the bearing layer at the pile end is unqualified.

[0120] The continuous stability of the bearing layer at the pile end is evaluated by making the continuous stability of the bearing layer at the pile end include two sub-indicators, namely, punching consistency and continuous stability of sample slag; the continuous stability of the bearing layer at the pile end is evaluated by comprehensively evaluating the continuous stability of the sample slag and the punching consistency. Compared with the method of evaluating the continuous stability of the bearing layer at the pile end based on the evaluation results of punching consistency or continuous stability of sample slag alone, the accuracy of judging the continuous stability of the bearing layer at the pile end can be effectively improved.

[0121] The method for evaluating the punching consistency based on the penetration information and the punching time information is the same as the method for evaluating the continuous stability of the pile end bearing layer in Example 1.

[0122] Among them, the method of evaluating the continuous stability of the sample slag based on the sample slag information belongs to the conventional technology in this professional and technical field. By comparing the color, hardness, lithological characteristics and particle size of the sample slag of each stroke section after excavating to the elevation range of the designed bearing layer, the continuous stability of the sample slag can be judged.

[0123] Embodiment 3:

[0124] Embodiment 3 provides a method for determining the reliability of the bearing layer at the end of a bored cast-in-place pile. The method for determining the reliability of the bearing layer at the end of a bored cast-in-place pile provided in Embodiment 3 is substantially the same as the method for determining the reliability of the bearing layer at the end of a bored cast-in-place pile provided in Embodiment 1, except that, after the pile well is excavated to the elevation range of the designed bearing layer, the hammer wear information of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer is also obtained.

[0125] Methods for evaluating the rock strength of the pile end bearing layer include:

[0126] Acquire a first mapping relationship between a second average penetration rate during the excavation process of the standard stroke section and a first compressive strength value of the standard stroke section;

[0127] Acquire a second mapping relationship between a first hammer claw wear ratio value during the excavation process of a standard stroke section and a first compressive strength value of the standard stroke section;

[0128] According to the penetration information, the first average penetration of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer is obtained;

[0129] According to the hammer wear information, the wear ratio value of the second hammer claw in each stroke section after the pile well is excavated to the elevation range of the designed bearing layer is obtained;

[0130] According to the obtained first mapping relationship and the first average penetration of each stroke section, a second compressive strength value of each stroke section is obtained; according to the obtained second mapping relationship and the second hammer claw wear ratio value of each stroke section, a third compressive strength value of each stroke section is obtained; according to the obtained second compressive strength value and third compressive strength value of each stroke section, the rock strength of the pile end bearing layer is evaluated;

[0131] If the second compressive strength value and the third compressive strength value of each stroke section are not less than the preset compressive strength value, the evaluation result of the rock strength of the pile end bearing layer is qualified, otherwise the evaluation result of the rock strength of the pile end bearing layer is unqualified.

[0132] Among them, the second mapping relationship can be obtained in a variety of ways, such as but not limited to: obtaining the second mapping relationship through comparative tests, obtaining the second mapping relationship by analyzing historical data of the same model of punching pile drivers, and calculating the second mapping relationship through the empirical coefficient between the hammer wear ratio and the rock compressive strength.

[0133] Among them, in this embodiment 3, the thickness of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer is 20 cma , the thickness of the standard stroke section is 20 cma ; The second mapping relationship is shown in Table 1.

[0134] Table 1 The second mapping relationship between the first hammer claw wear ratio value and the first compressive strength value

[0135] <![CDATA[First compressive strength value σ ei > The first hammer claw wear ratio value A <![CDATA[σ ei ≥120MPa]]> A≥20％ <![CDATA[60MPa≤σ ei <120MPa]]> 8％≤A<20％ <![CDATA[30MPa≤σ ei <60MPa]]> 2％≤A<8％ <![CDATA[15MPa≤σ ei <30MPa]]> 0＜A＜2％ <![CDATA[σ ei <15MPa]]> 0

[0136] In this embodiment 3, in the second mapping relationship, the first hammer claw wear ratio value and the first compressive strength value are both range values. When the second hammer claw wear ratio value is within the value range of the corresponding first compressive strength value, the obtained third compressive strength value is the minimum value in the value range of the corresponding first compressive strength value.

[0137] Embodiment 4:

[0138] According to the method for determining the reliability of the bearing layer at the end of a bored cast-in-place pile provided in Example 1, Example 4 provides a system for determining the reliability of the bearing layer at the end of a bored cast-in-place pile, including an acquisition module, an evaluation module and a judgment module.

[0139] The acquisition module is used to obtain effective thickness information, penetration information and punching time information of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer, surrounding surface settlement information of the pile well, mud information in the well, well bottom flatness information and well wall inclination information after the pile well is excavated to the elevation range of the designed bearing layer; and send the obtained effective thickness information, penetration information, punching time information, hammer wear information, surrounding surface settlement information, mud information in the well, well bottom flatness information and well wall inclination information to the evaluation module;

[0140] The evaluation module is used to evaluate multiple determination indicators of the pile end bearing layer according to the obtained effective thickness information, penetration information, punching time information, hammer wear information, surrounding surface settlement information, mud information in the well, well bottom flatness information and well wall inclination information, and send the evaluation results of each determination indicator to the judgment module;

[0141] The judgment module is used to judge whether the bearing layer at the pile end is reliable according to the evaluation results of various judgment indicators.

[0142] The method and system for determining the reliability of the bearing layer at the end of a bored pile provided by this embodiment have at least the following technical effects or advantages:

[0143] 1. The method for determining the reliability of the bearing layer at the end of a bored pile provided by the present invention utilizes effective thickness information, penetration information, punching time information, hammer wear information, surrounding surface settlement information, mud information in the well, well bottom flatness information, and well wall inclination information to evaluate seven indicators of the bearing layer at the end of the pile. The method can comprehensively evaluate the integrity of the bearing layer at the end of the pile, the continuous stability of the bearing layer at the end of the pile, the mechanical characteristics of the bearing layer at the end of the pile (by evaluating the rock strength of the bearing layer at the end of the pile) and the construction factors of pile well excavation (by evaluating the four indicators of surface settlement, well bottom flatness, well wall inclination, and effective thickness), and can effectively improve the accuracy of determining the reliability of the bearing layer at the end of the pile, thereby avoiding the occurrence of failures in deep pile foundation projects.

[0144] 2. By obtaining the change value of the mud level height in the first well corresponding to each construction interval period after the pile well is excavated to the elevation range of the designed bearing layer, and the change value of the mud level height in the second well within the first preset time range after the pile well excavation construction is completed; the permeability of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer can be obtained through the change value of the mud level height in the second well and the change value of the mud level height in each first well, so as to provide a judgment basis for judging the integrity of the bearing layer at the pile end.

[0145] 3. By obtaining the difference between the first average penetration of any two adjacent stroke sections after the pile well is excavated to the elevation range of the designed bearing layer and the difference between the punching time of any two adjacent stroke sections, it is possible to provide a basis for judging the continuous stability of the bearing layer at the pile end.

[0146] 4. By making the continuous stability of the bearing layer at the pile end an indicator including the two sub-indicators of punching consistency and continuous stability of sample slag; by comprehensively evaluating the continuous stability of sample slag and punching consistency to evaluate the continuous stability of the bearing layer at the pile end, compared with the method of evaluating the continuous stability of the bearing layer at the pile end based on the evaluation results of punching consistency or continuous stability of sample slag alone, the accuracy of judging the continuous stability of the bearing layer at the pile end can be effectively improved.

[0147] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for determining the reliability of the bearing layer at the end of a bored pile, characterized in that: include: After the pile well is excavated to the elevation range of the designed bearing layer, effective thickness information, penetration information and punching time information of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer, surrounding surface settlement information of the pile well, mud information in the well, well bottom flatness information and well wall inclination information are obtained; Evaluate multiple determination indicators of the pile end bearing layer according to the effective thickness information, the penetration information, the punching time information, the hammer wear information, the surrounding surface settlement information, the mud information in the well, the well bottom flatness information and the well wall inclination information; According to the evaluation results of various determination indicators, whether the bearing layer at the pile end is reliable is determined; The multiple judgment indicators include seven indicators: surface settlement, well bottom flatness, well wall inclination, integrity of pile end bearing layer, continuous stability of pile end bearing layer, rock strength of pile end bearing layer, and effective thickness.

2. The method for determining the reliability of the bearing layer at the end of a bored pile according to claim 1, characterized in that: If the evaluation results of the determination indicators are all qualified, the pile end bearing layer is determined to be reliable; if the evaluation result of any one of the determination indicators is unqualified, the pile end bearing layer is determined to be unreliable.

3. The method for determining the reliability of the bearing layer at the end of a bored pile according to claim 2, characterized in that: The method for evaluating the integrity of the pile end bearing layer includes: According to the mud information in the well, the first well mud level height change value corresponding to each construction interval period after the pile well is excavated to the elevation range of the designed bearing layer is obtained, and the second well mud level height change value within the first preset time range after the pile well excavation construction is completed is obtained; evaluating the integrity of the pile end bearing layer according to the obtained value of the change in the mud level in the first well and the value of the change in the mud level in the second well; If the change values ​​of the mud level height in each of the first wells are less than the first preset height change value, and the change value of the mud level height in the second well is less than the second preset height change value, then the evaluation result of the integrity of the bearing layer at the pile end is qualified; otherwise, the evaluation result of the integrity of the bearing layer at the pile end is unqualified.

4. The method for determining the reliability of the bearing layer at the end of a bored pile according to claim 3 is characterized in that: The method for evaluating the continuous stability of the pile end bearing layer includes: According to the penetration information and the punching time information, the first average penetration and punching time of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer are obtained; The continuous stability of the pile end bearing layer is evaluated according to the first average penetration and punching time value of each stroke section; If the difference between the first average penetration rates of any two adjacent stroke segments is less than a first preset difference, and the difference between the punching times of any two adjacent stroke segments is less than a second preset difference, then the evaluation result of the continuous stability of the pile end bearing layer is qualified; otherwise, the evaluation result of the continuous stability of the pile end bearing layer is unqualified.

5. The method for determining the reliability of the bearing layer at the end of a bored pile according to claim 3 is characterized in that: After the pile well is excavated to the elevation range of the designed bearing layer, the sample slag information of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer is also obtained; The continuous stability of the pile end bearing layer is a determination index including punching consistency and continuous stability of sample slag. The method for evaluating the continuous stability of the pile end bearing layer includes: The punching consistency is evaluated according to the penetration information and the punching time information, and the continuous stability of the sample slag is evaluated according to the sample slag information; If the evaluation results of the two judgment sub-indicators of the punching consistency and the continuous stability of the sample slag are both qualified, the evaluation result of the continuous stability of the pile end bearing layer is qualified; otherwise, the evaluation result of the continuous stability of the pile end bearing layer is unqualified.

6. The method for determining the reliability of the bearing layer at the end of a bored pile according to claim 3 is characterized in that: The method for evaluating the surface subsidence includes: According to the surrounding surface settlement information, the maximum surface settlement value around the pile well during the entire process of pile well excavation construction is obtained; Evaluating the surface settlement according to the maximum surface settlement value of the surrounding area; If the maximum surface settlement value of the surrounding area is less than the preset surface settlement value, the evaluation result of the surface settlement is qualified; otherwise, the evaluation result of the surface settlement is unqualified.

7. The method for determining the reliability of the bearing layer at the end of a bored pile according to claim 3 is characterized in that: The method for evaluating the rock strength of the pile end bearing layer includes: Acquire a first mapping relationship between a second average penetration rate during the excavation process of a standard stroke section and a first compressive strength value of the standard stroke section; According to the penetration information, a first average penetration of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer is obtained; Obtaining a second compressive strength value of each stroke segment according to the obtained first mapping relationship and the first average penetration of each stroke segment, and evaluating the rock strength of the pile end bearing layer according to the obtained second compressive strength value of each stroke segment; If the second compressive strength value of each stroke segment is not less than the preset compressive strength value, the evaluation result of the rock strength of the pile end bearing layer is qualified; otherwise, the evaluation result of the rock strength of the pile end bearing layer is unqualified.

8. The method for determining the reliability of the bearing layer at the end of a bored pile according to claim 3 is characterized in that: After the pile well is excavated to the elevation range of the designed bearing layer, the hammer wear information of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer is also obtained; The method for evaluating the rock strength of the pile end bearing layer includes: Acquire a first mapping relationship between a second average penetration rate during the excavation process of a standard stroke section and a first compressive strength value of the standard stroke section; Acquire a second mapping relationship between a first hammer claw wear ratio value during excavation of a standard stroke section and a first compressive strength value of the standard stroke section; According to the penetration information, a first average penetration of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer is obtained; According to the hammer wear information, the second hammer claw wear ratio value of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer is obtained; According to the obtained first mapping relationship and the first average penetration of each stroke segment, a second compressive strength value of each stroke segment is obtained; according to the obtained second mapping relationship and the second hammer claw wear ratio value of each stroke segment, a third compressive strength value of each stroke segment is obtained; according to the obtained second compressive strength value and third compressive strength value of each stroke segment, the rock strength of the pile end bearing layer is evaluated; If the second compressive strength value and the third compressive strength value of each stroke segment are not less than the preset compressive strength value, the evaluation result of the rock strength of the pile end bearing layer is qualified; otherwise, the evaluation result of the rock strength of the pile end bearing layer is unqualified.

9. The method for determining the reliability of the bearing layer at the end of a bored pile according to claim 3, characterized in that: The method for evaluating the well bottom flatness includes: According to the well bottom flatness information, the well bottom flatness value of the pile well after the pile well excavation construction is completed is obtained. Evaluating the well bottom flatness according to the obtained well bottom flatness value; If the well bottom flatness value is not greater than the preset flatness value, the evaluation result of the well bottom flatness is qualified, otherwise the evaluation result of the well bottom flatness is unqualified.

10. The method for determining the reliability of the bearing layer at the end of a bored pile according to claim 3, characterized in that: The method for evaluating the wellbore inclination includes: According to the well wall inclination information, the well wall inclination value of the pile well after the pile well excavation construction is completed is obtained. Evaluating the well wall inclination according to the obtained well wall inclination value; If the well wall inclination value is not greater than the preset inclination value, the evaluation result of the well wall inclination is qualified; otherwise, the evaluation result of the well wall inclination is unqualified.

11. The method for determining the reliability of the bearing layer at the end of a bored pile according to claim 3, characterized in that: The method for evaluating the effective thickness includes: According to the effective thickness information, the effective thickness value of the portion of the pile well within the elevation range of the designed bearing layer after the pile well excavation construction is completed is obtained; evaluating the effective thickness according to the obtained effective thickness value; If the effective thickness value is not less than the preset thickness value, the evaluation result of the effective thickness is qualified; otherwise, the evaluation result of the effective thickness is unqualified.

12. A system for determining the reliability of the bearing layer at the end of a bored pile, characterized in that: Including acquisition module, evaluation module and judgment module, The acquisition module is used to obtain effective thickness information, penetration information and punching time information of each stroke section after the pile well is excavated to the elevation range of the designed bearing layer, surrounding surface settlement information of the pile well, mud information in the well, well bottom flatness information and well wall inclination information after the pile well is excavated to the elevation range of the designed bearing layer; and sending the obtained effective thickness information, penetration information, punching time information, hammer wear information, surrounding surface settlement information, well mud information, well bottom flatness information and well wall inclination information to the evaluation module; The evaluation module is used to evaluate multiple determination indicators of the pile end bearing layer according to the obtained effective thickness information, penetration information, punching time information, hammer wear information, surrounding surface settlement information, mud information in the well, well bottom flatness information and well wall inclination information, and send the evaluation results of each determination indicator to the judgment module; The judgment module is used to judge whether the pile end bearing layer is reliable according to the evaluation results of various judgment indicators. The system for determining the reliability of the bearing layer at the end of a bored cast-in-place pile is used to execute the steps in the method for determining the reliability of the bearing layer at the end of a bored cast-in-place pile as claimed in any one of claims 1 to 11.

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