Method for identifying side hole transmission wave method pile bottom depth based on graphic features

Abstract

The invention discloses a method for identifying the pile bottom depth by a side hole transmission wave method based on graphic features, which comprises the steps of conventional detection and analysis, special working condition judgment, graphic feature identification and pile bottom end position determination, and the graphic feature identification determines the pile bottom end position by observing the tested oscillogram features. According to the method for identifying the pile bottom depth based on the graphic features through the side hole transmission wave method, the position of the pile bottom end can be accurately determined under special working conditions such as large side hole distance testing, layered or saturated foundations and socketed piles which are difficult to apply by some conventional methods, and the pile bottom depth can be accurately determined by identifying special graphs such as oblique N-shaped features or waveform faults in an oscillogram. According to the method, the position of the bottom end of the pile can be judged without complex calculation and analysis processes, the method has the advantages of being simple, convenient, rapid and easy to distinguish, the position of the bottom end of the pile can be accurately determined, the problem that the position of the bottom end of the pile cannot be effectively recognized under the special working condition or the side hole distance is large is solved, and high precision is achieved.

Description

Technical Field

[0001] The invention relates to the technical field related to pile bottom depth detection, and in particular to a method for identifying pile bottom depth using a side-hole transmission wave method based on graphic features. Background Art

[0002] By identifying the bottom position of the pile, the actual length of the pile can be accurately known and whether it has reached the designed length can be determined, thereby ensuring that the pile foundation can provide sufficient bearing capacity and ensure the stability and safety of structures such as buildings. However, the existing pile bottom depth detection method still has certain defects when used.

[0003] During use, the conventional method is to determine the pile length based on the travel time analysis of the first arrival wave. The wave propagation path is to propagate through the pile body and then be transmitted to the side test hole at a certain depth of the pile body or pile bottom to be received by the detector. However, under some special working conditions, such as testing side hole distances with large distances, layered or saturated foundations, rock-embedded piles, etc., it is difficult to detect the first arrival wave transmitted by the side hole in the side hole transmission waveform diagram of the test. At this time, it is often difficult to determine the pile bottom position based on the existing test analysis method.

[0004] In view of the above problems, it is urgently necessary to make innovative designs based on the original method of identifying the pile bottom depth by the side-hole transmission wave method based on graphic features. Therefore, we proposed a method of identifying the pile bottom depth by the side-hole transmission wave method based on graphic features, which can solve the above problems well. Summary of the invention

[0005] The purpose of the present invention is to provide a method for identifying the pile bottom depth by the side-hole transmission wave method based on graphic features, so as to solve the problem that the conventional method currently on the market proposed in the above background technology is to determine the pile length based on the travel time analysis of the first arrival wave, and the propagation path of the wave is to propagate through the pile body and then be transmitted to the side measuring hole at a certain depth of the pile body or pile bottom to be received by the detector. However, under some special working conditions, such as testing the side hole distance is large, layered or saturated foundation, rock-embedded piles and other conditions, it is difficult to detect the first arrival wave of the side hole transmission in the side hole transmission waveform diagram of the test, and it is often difficult to determine the pile bottom position based on the existing test analysis method.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a method for pile bottom depth based on graphic feature recognition by side-hole transmission wave method, including conventional detection and analysis, special working condition judgment, graphic feature recognition and pile bottom position determination. The graphic feature recognition can determine the pile bottom position simply, quickly and accurately by observing the waveform characteristics of the test, providing reliable technical support for the quality detection and analysis of pile foundation engineering.

[0007] Preferably, the conventional detection and analysis adopts the side hole transmission wave method to determine the pile length based on the first arrival wave travel time analysis. The wave propagation path is that the wave propagates through the pile body and then is transmitted to the side measurement hole at a certain depth of the pile body or pile bottom to be received by the detector.

[0008] Preferably, the special operating condition judgment determines which method to use for detection by judging whether it is in a special operating condition.

[0009] Preferably, the graphic feature recognition can determine the pile bottom position by identifying special graphics in the waveform graph without complicated calculation and analysis processes.

[0010] Preferably, the graphic feature recognition is performed by observing the waveform features. If an oblique N-shaped feature is present, the pile bottom position can be determined based on the horizontal section position; if a waveform fault is present and the fault position is located on the bedrock surface, then the waveform fault position is the pile bottom position.

[0011] Preferably, the pile bottom position is determined based on the above-mentioned graphic feature recognition result, so as to evaluate and analyze the pile bottom depth.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: the method for identifying the pile bottom depth by the side-hole transmission wave method based on graphic features can accurately determine the pile bottom position under special working conditions where some conventional methods are difficult to apply, such as testing a large side-hole distance, layered or saturated foundation, rock-embedded piles, etc., and the pile bottom position can be determined by identifying special graphics such as oblique N-shaped features or waveform faults in the waveform graph, without the need for complex calculation and analysis processes, and has the characteristics of being simple, fast and easy to identify. This method can determine the pile bottom position more accurately, solves the problem of determining the pile bottom position when the first arrival wave cannot be effectively identified under special working conditions or the side-hole distance is far, and has high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a flow chart of the overall method of the present invention; Figure 2 It is a graphic feature recognition diagram of the present invention; Figure 3 It is the side hole transmission waveform diagram under the saturated foundation of the present invention; Figure 4 It is a side hole transmission waveform diagram of a pile foundation under the layered foundation of the present invention; Figure 5 It is the side hole transmission waveform diagram of the end bearing pile of the present invention. DETAILED DESCRIPTION

[0014] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] Example: Figure 1 and Figure 2 The technical solution shown includes conventional detection and analysis, special working condition judgment, graphic feature recognition and pile bottom position determination. The graphic feature recognition can determine the pile bottom position simply, quickly and accurately by observing the waveform characteristics of the test, providing reliable technical support for the quality detection and analysis of pile foundation engineering. Conventional detection and analysis adopts the side hole transmission wave method to detect, and the pile length is determined based on the first wave travel time analysis. The wave propagation path is transmitted through the pile body and then transmitted to the side measurement hole at a certain depth of the pile body or pile bottom to be received by the detector. The special working condition judgment determines which method to use for detection by judging whether it is in a special working condition. Graphic feature recognition can determine the pile bottom position by identifying special graphics in the waveform without complicated calculation and analysis process. Graphic feature recognition is identified by observing the waveform characteristics. If an oblique N-shaped feature is presented, the pile bottom position can be determined according to the horizontal section position; if a waveform fault is presented and the fault position is located on the bedrock surface, then the waveform fault position is the pile bottom position. The pile bottom position is determined based on the above-mentioned graphic feature recognition results to determine the pile bottom position for evaluating and analyzing the pile bottom depth.

[0016] In the pile bottom position detection process, conventional detection and analysis are first carried out. The side hole transmission wave method is used to determine the pile length based on the first arrival wave travel time analysis. The wave propagates through the pile body and then transmits from the pile body or pile bottom to the side test hole at a certain depth and is received by the detector. Then, special working condition judgment is carried out. It is necessary to clarify whether it is in special working conditions such as large side hole distance, layered or saturated foundation, rock-embedded piles, etc. If it is in special working conditions and the side hole transmission waveform diagram of the test is difficult to detect the first arrival wave of the side hole transmission, the graphic feature recognition link is entered; if the first arrival wave can be detected, the pile bottom position is determined by the conventional method, and in the graphic feature recognition link, the pile bottom position is determined by the conventional method. When distinguishing, carefully observe the waveform characteristics. If it shows an oblique N-shaped feature, the bottom end of the pile can be determined according to the horizontal section position; if a waveform fault is present and the fault position is located on the bedrock surface, then the waveform fault position is the bottom end of the pile. Finally, the bottom end of the pile is determined according to the graphic feature recognition results, and then used to evaluate and analyze the depth of the bottom end of the pile. This method has significant beneficial effects. It breaks through the limitations of conventional detection methods under special working conditions. Through a unique graphic feature recognition method, it can easily, quickly and accurately determine the bottom end of the pile, providing reliable technical support for quality inspection and analysis of pile foundation projects.

[0017] The method of identifying the pile bottom depth by the side-hole transmission wave method based on graphic features can accurately determine the pile bottom position under special conditions where some conventional methods are difficult to apply, such as testing a large side-hole distance, layered or saturated foundation, rock-embedded piles, etc., and the pile bottom position can be determined by identifying special graphics such as the oblique N-shaped feature or waveform fault in the waveform diagram. It does not require complicated calculation and analysis processes and is simple, fast and easy to identify. This method can determine the pile bottom position more accurately, solves the problem of determining the pile bottom position when the first arrival wave cannot be effectively identified under special conditions or the side-hole distance is far, and has high accuracy.

[0018] To obtain the waveform using the side-hole shooting method, it is necessary to first conduct a comprehensive survey of the test site to understand the distribution of piles, the surrounding environment, geological conditions and other information, so as to provide a basis for the subsequent selection of drilling positions and the formulation of the test plan. Drill holes at a suitable location on the pile side. The holes should be kept parallel to the pile body as much as possible, and the distance from the pile body is generally about 0.5-2m. The drilling depth must exceed the expected pile bottom depth by 2-3m. For example, if the expected pile bottom depth is 20m, the drilling depth should reach 22-23m. Use professional drilling equipment. Prepare to drill a hole. During the drilling process, ensure the verticality and stability of the hole wall to prevent the hole from collapsing. After the drilling is completed, bury a measuring tube in the hole. The measuring tube is generally made of PVC. The diameter should be able to meet the smooth lowering and lifting of the detector. The bottom of the measuring tube needs to be sealed to prevent dirt and other debris from entering. Then fill the measuring tube with clean water to ensure that the detector is well coupled with the surrounding medium. Connect the detector to the signal transmission line to ensure a firm connection. The detector should have high sensitivity and good frequency response characteristics to accurately receive the transmitted wave signal. , slowly lower the detector to the borehole pipe mouth or pipe bottom. During the lowering process, be careful to avoid the detector colliding with the hole wall and causing damage. On the pile top (or the upper structure such as the pedestal and pile cap connected to the pile top), select a suitable excitation position. Usually, a hand hammer or force rod is used to knock in the vertical direction to generate a stress wave that propagates downward along the pile body. The magnitude and action time of the excitation force should be adjusted according to the type and size of the pile to ensure that a clear and identifiable transmission wave signal can be generated. Connect the signal transmission line of the detector to the multi-channel synchronous elastic wave acquisition instrument to ensure that the signal can be accurately transmitted to the acquisition instrument. At the same time, if a trigger sensor (such as an accelerometer) is used, it is installed on the top of the pile to trigger signal acquisition to ensure that the acquisition instrument works synchronously with the excitation vibration. In an excitation-detection cycle, the detector is located at the initial position (the borehole pipe mouth or pipe bottom). The mechanical wave is generated on the pile through the excitation device. At this time, the acquisition instrument records the vibration signal received by the detector at this depth. After completing one acquisition, the height of the detector is lowered or raised by 0.2-1m (the specific step size can be adjusted according to the detection accuracy requirements. Generally, the higher the accuracy requirements, the smaller the step size), excite again and collect the signal at the new depth, repeat this operation until the detector reaches the bottom or top of the borehole, and complete the signal collection at different positions within the entire borehole depth range. After one measurement cycle, the approximate range of the pile bottom depth can be determined based on the preliminary collected data. To improve the detection accuracy, the measurement points can be appropriately encrypted within the approximate pile bottom depth range, that is, the detector movement step size can be reduced, and signal collection can be performed again. The large amount of collected data is screened to remove data with obvious abnormalities or large interference. For example, if the signal at a certain depth fluctuates violently and is inconsistent with other measurements, The characteristics of the point signals are very different. After being analyzed and confirmed as interference signals, they are removed, and the valid data are sorted and arranged in depth order, with depth as the horizontal coordinate and the first arrival wave travel time of the signal received by the detector as the vertical coordinate. The sorted data are plotted in the coordinate system to form a time-depth signal diagram. In the figure, under normal circumstances, the first arrival wave travel time of the measuring point from the top of the pile to the bottom of the pile can fit a straight line, and near the depth of the pile bottom, the first arrival wave travel time will gradually deviate from the fitting straight line to the right as a whole. The deviation from the starting point is the inflection point. Through the analysis of the inflection point in the time-depth signal diagram and the relevant correction formula, the inflection point depth is corrected, and finally a more accurate pile bottom depth is obtained. .

[0019] The side hole transmission waveform test under saturated foundation is shown in the figure below. The designed pile length is 12m, the measured hole depth is 26m, the side hole distance is 2m, and the detector detection interval is 0.5m. Due to the large side hole distance and the saturated foundation, the takeoff of the first arrival wave in the test signal after horizontal excitation on the pile side is not obvious, and it is difficult to determine the pile bottom position based on the existing first arrival wave takeoff and travel time. However, the figure shows an oblique N-shaped feature composed of three broken lines. Through travel time analysis, segment 1 is a direct S wave from the excitation point to the detector, and segment 3 is a direct S wave transmitted to the pile end and then to the detector after excitation. The end point of segment 1 and segment 3 are both near the pile end 12m. Connecting their ends is the horizontal segment 2. The position of the horizontal segment of the oblique N-shaped feature is the pile bottom position, as shown in Figure 3 As shown in the figure, this method solves the problem of determining the pile bottom position when the first arrival wave cannot be effectively identified in partially saturated foundation or the side hole distance is far, and has high accuracy.

[0020] The side hole transmission waveform test of a pile foundation under a layered foundation is shown in the figure below. The designed pile length is 12m, the measured hole depth is 26m, the side hole distance is 2m, and the detector detection interval is 0.5m during the test. Due to the large waveform disturbance under the layered foundation and the large side hole distance, the takeoff of the first arrival wave in the test signal after horizontal excitation on the pile side is not obvious, and it is difficult to determine the bottom end position of the pile based on the existing first arrival wave takeoff and travel time. A significant oblique N-shaped feature is found in the test waveform. According to the position of the horizontal section in the feature, it is determined that the bottom end of the pile is 12m. Figure 4As shown in the figure, this method solves the problem of determining the pile bottom position when the first arrival wave cannot be effectively identified in some layered foundations or the side hole distance is far, and has high accuracy.

[0021] The side hole transmission waveform test of an end-bearing pile is shown in the figure below. The designed pile length is 12m and the measured hole depth is 26m. During the drilling and measuring hole process, it was found that the bedrock surface was 12m below the ground, the side hole distance was 2m, and the detector detection interval was 0.5m during the test. Since the pile end is located on the bedrock surface and the side hole distance is large, the first arrival wave in the test signal after horizontal excitation on the pile side is not obvious, and no effective signal is collected below the pile bottom. It is difficult to determine the pile bottom position based on the existing first arrival wave jump and travel time. Figure 5 As shown in the figure, when the pile end is located at the bedrock or embedded in the bedrock, the wave velocity of the pile body is close to that of the bedrock, resulting in wave energy dissipation and difficulty for the detector to receive effective signals. Combined with the position of the bedrock surface in the borehole and the fact that no effective side-hole transmission wave signal is collected below 12 m, the pile bottom is located at 12 m.

[0022] In the description of the present invention, unless otherwise specified, "plurality" means two or more; the orientations or positional relationships indicated by terms such as "upper", "lower", "left", "right", "inside", "outside", "front end", "rear end", "head" and "tail" are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention; in addition, the terms "first", "second", "third" and the like are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0023] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] 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 method for pile bottom depth based on pattern feature recognition of side hole transmission wave method, comprising conventional detection and analysis, special working condition judgment, pattern feature recognition and pile bottom position determination, characterized in that: The graphic feature recognition can determine the pile bottom position simply, quickly and accurately by observing the waveform features of the test, thus providing reliable technical support for the quality inspection and analysis of pile foundation engineering.

2. The method for identifying pile bottom depth based on the side hole transmission wave method based on graphic features according to claim 1 is characterized in that: The conventional detection and analysis adopts the side hole transmission wave method to determine the pile length based on the first arrival wave travel time analysis. The wave propagation path is that the wave propagates through the pile body and then is transmitted to the side measurement hole at a certain depth of the pile body or pile bottom and received by the detector.

3. The method for identifying pile bottom depth by side hole transmission wave method based on graphic features according to claim 1, characterized in that: The special operating condition judgment determines which method to use for detection by judging whether the special operating condition exists.

4. The method for identifying pile bottom depth based on the side hole transmission wave method based on graphic features according to claim 1 is characterized in that: The graphic feature recognition can determine the pile bottom position by identifying special graphics in the waveform graph without complicated calculation and analysis processes.

5. The method for identifying pile bottom depth by side hole transmission wave method based on graphic features according to claim 1, characterized in that: The graphic feature recognition is performed by observing the waveform features. If an oblique N-shaped feature is present, the pile bottom position can be determined based on the horizontal section position; if a waveform fault is present and the fault position is located on the bedrock surface, then the waveform fault position is the pile bottom position.

6. The method for identifying pile bottom depth based on the side hole transmission wave method based on graphic features according to claim 1, characterized in that: The pile bottom position is determined based on the above-mentioned graphic feature recognition result, and is used to evaluate and analyze the pile bottom depth.

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