CN108930295B - Low-strain eccentric knocking single-point sampling method for foundation pile - Google Patents
Low-strain eccentric knocking single-point sampling method for foundation pile Download PDFInfo
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- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
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Abstract
The invention provides a foundation pile low-strain eccentric knocking single-point sampling method, which is applied to a common building solid circular pile body and comprises the following steps: setting a knocking point on the pile top surface of the solid pile of the building: under the condition that the Poisson ratio of the pile body concrete is known, a knocking point is arranged on a position (0.67-0.5 upsilon) R on any radius of the surface of the pile top, wherein upsilon is the Poisson ratio of the pile body concrete, and R is the radius of a foundation pile; under the condition that the Poisson ratio of the pile body concrete is unknown, the knocking point is arranged at the 2/3 position of the radius of the reinforcement cage on any radius of the surface of the pile top; setting sampling points on the pile top surface of the solid pile of the building, wherein the sampling points are positioned on the diameter vertical to the radius of the knocking point and are respectively within 0.15R range from the left side to the right side of the center of the pile, and the total length of the sampling points is within 0.3R range; and mounting a sensor on the sampling point, connecting the sensor to the low-stress detector, and acquiring a test signal from the sampling point when a knocking action at the knocking point is received.
Description
Technical Field
The invention relates to the field of building detection, in particular to a low-strain double-speed signal average detection method for a solid pile of a building.
Background
The existing common foundation pile low-strain detection method applies low-energy transient knocking to the surface of the pile top, impact waves generated by knocking are transmitted downwards along a pile body, reflected waves are generated when the impact waves encounter a medium surface with changed wave impedance or the pile bottom, and the quality of the pile body is judged according to the signal characteristics of the reflected waves.
At present, the low strain detection scheme of the existing solid circular foundation pile has some problems:
firstly, for low strain detection of a solid circular foundation pile, pile center knocking is adopted in the existing foundation pile detection specifications and most researches, however, the pile center is only a very special point on the pile top surface, and the pile center knocking is only a special case of the pile top surface knocking at any point, namely, the existing sampling scheme limits the knocking point position to the pile center. However, in actual engineering, the center of the pile is the position of a conduit for pouring concrete, and due to improper pipe drawing, construction defects often occur at the position, and eccentric knocking is required at the moment. Therefore, the center tap cannot be guaranteed in a practical situation.
Secondly, when the solid pile adopts eccentric knocking, at the moment, longitudinal waves which are vertically propagated are generated in the pile body like the central knocking, the eccentric knocking also generates obvious eccentric action shear waves along with the increase of the pile diameter, and the three-dimensional interference effect is also obviously different from that under the central knocking. However, in the current scheme of the low-strain vertical eccentric knocking aspect of the foundation pile, the eccentric knocking is not considered, and how to eliminate special three-dimensional interference signals and eccentric action shear waves generated by the eccentric knocking is not considered.
Therefore, a sampling scheme capable of effectively eliminating interference signals when the pile top surface is knocked at any point is needed.
Disclosure of Invention
The embodiment of the invention aims to provide a low-strain double-speed signal average detection method for a solid pile of a building, which is used for helping to enlarge the selection range of a knocking point of a low-strain test of the solid pile and accurately judge the integrity of a pile body of the solid pile of the building.
In order to solve the problems in the low strain detection of the existing solid pile, the invention adopts the technical scheme that: a low-strain double-speed signal average detection method for a solid pile of a building is applied to a solid circular pile body of the building, and comprises the following steps:
arranging knocking points on the pile top surface of the solid pile of the building;
under the condition that the Poisson ratio of the concrete of the pile body is known, two signal acquisition devices are arranged on the surface of the pile top of the solid pile of the building at a position (0.67-0.5 upsilon) R on two radiuses which form an angle of 45 degrees and an angle of 135 degrees with the radius of a knocking point, and are used as measuring points for the solid pile body of the building, wherein upsilon is the Poisson ratio of the concrete of the pile body, and R is the radius of a foundation pile;
under the condition that the Poisson ratio of concrete of a pile body is unknown, two signal acquisition devices are arranged on the pile top surface of the solid pile of the building at positions 2/3 of the radius of a reinforcement cage on two radii forming 45 degrees and 135 degrees with the radius of a knocking point, and are used as measuring points for the solid pile body of the building;
when the knocking action at the knocking point is received, the measuring point signals from each signal acquisition device are acquired at the same time, and a double-speed test curve containing each measuring point signal is obtained; and carrying out average processing on the double-speed curve to obtain a detection result of the solid pile body of the building. Further, the solid pile of the building is specifically a solid circular foundation pile.
Further, the knocking action is generated by vertically knocking through a force hammer or a force rod.
Further, the striking point positions are as follows: any point on the pile top surface, including the pile center.
Further, the signal acquisition device is a probe or a sensor.
Further, the signal acquisition device is adhered to the top surface of the solid pile of the building through adhesive substances such as glue, butter or plasticine.
Further, the signal acquisition device is connected with an information processing device for processing the signals acquired by the signal acquisition device.
Further, the information processing device is specifically a low strain detector having a dual speed mode.
Further, the step of simultaneously acquiring the measuring point signals from each signal acquisition device and obtaining the double-speed test curve containing each measuring point signal when the knocking action at the knocking point is received is specifically as follows:
when the signal acquisition device receives a knocking action at a knocking point, the information processing device connected with the signal acquisition device is triggered, and the information processing device simultaneously acquires and records measuring point signals from the two signal acquisition devices positioned on the top surface of the solid pile of the building and obtains a corresponding double-speed test curve.
The method comprises the following steps of carrying out average processing on a double-speed curve to obtain a detection result of the solid pile body of the building, wherein the detection result comprises the following specific steps:
the two-speed signals obtained by the information processing apparatus are averaged to generate a single speed curve.
The technical scheme provided by the embodiment of the invention has the following beneficial effects: the invention relates to a low-strain double-speed signal average detection method for a solid pile of a building, which comprises the steps of knocking at any point on the top surface of the solid pile body of the building, utilizing two signal acquisition devices to obtain double-speed test curves of two sampling point positions on the radius of 45 degrees and 135 degrees with the knocking point, and carrying out average processing on double-speed signals to remarkably eliminate three-dimensional interference signals generated at the top of the pile due to eccentric knocking and eccentric action shear waves propagated along the pile body. The signal average obtains a single signal curve, and the single signal curve can help to judge the integrity of the solid pile body of the building more accurately.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, some embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
Fig. 1 is a schematic flow chart of a low-strain double-speed signal average detection method for a solid pile of a building according to the present invention.
Fig. 2 is a schematic structural diagram of a low-strain double-speed signal average detection method for a solid pile of a building according to the present invention.
FIG. 3 is a schematic diagram of the structure shown in FIG. 2, under the conditions of the longitudinal wave velocity of concrete 4050m/s, the Poisson ratio of 0.28, the pile diameter of 2.9m, the pile length of 25m and the load pulse width of 1.6ms, the effect of time-course curves before and after averaging low-strain double-speed signals sampled at 0.75R on any radius of the pile top surface and at 0.53R on the radius of 45 degrees and 135 degrees from the radius of the knocking point. Where 0.53R is the sampling position obtained by substituting a Poisson ratio of 0.28 into (0.67-0.5 upsilon) R.
FIG. 4 is a schematic diagram showing the comparison of time-course curves of low-strain dual-speed average signals sampled at 0.53R on a radius of 45 degrees and a radius of 135 degrees with a knocking point when the structure shown in FIG. 2 is knocked at 0R, 0.25R, 0.55R and 0.75R of any radius of the top surface of the pile under the conditions of the longitudinal wave velocity of concrete 4050m/s, the Poisson ratio of 0.28, the pile diameter of 2.9m, the pile length of 25m and the load pulse width of 1.6 ms. Where 0.53R is the sampling position obtained by substituting a Poisson ratio of 0.28 into (0.67-0.5 upsilon) R.
FIG. 5 is a comparison graph of time-course curves of low-strain double-speed average signals sampled at 0.53R on the radius of 45 degrees and 135 degrees from the radius of a knocking point when the low-strain double-speed average signal of a solid pile of a building is knocked at 0.75R on the arbitrary radius of the top surface of the pile under the conditions of the longitudinal wave velocity of concrete 4050m/s, the Poisson ratio of 0.28, the pile diameter of 2.9m, the pile length of 25m and the load pulse width of 1.6ms, and sampled at the radius of 2/3 degrees from the center of the pile when the low-strain double-speed average signal is knocked at the midpoint of the top surface of the pile in the prior art.
Fig. 6 is an equivalent schematic diagram of the structural schematic diagram shown in fig. 2.
Fig. 7 is a schematic structural diagram of an alternative low-strain double-speed signal average detection method for a solid pile of a building.
FIG. 8 is a schematic diagram of the alternative structure shown in FIG. 7, which is a comparison diagram of time-course curves of low-strain signals sampled at 0R (pile midpoint), 0.05R, 0.1R and 0.15R from the pile midpoint on a diameter perpendicular to the radius of a knocking point when the knocking is performed at 0.53R of any radius of the surface of the pile top under the conditions of the concrete longitudinal wave velocity of 4050m/s, the Poisson ratio of 0.28, the pile diameter of 2.9m, the pile length of 25m and the load pulse width of 1.6 ms; wherein R is the radius, and 0.53R is the tapping point position obtained by substituting Poisson's ratio of 0.28 into (0.67-0.5 upsilon) R.
FIG. 9 is a comparison graph of time-course curves of signals acquired at the midpoint of a pile by the alternative structural diagram shown in FIG. 7 and dual-speed average signals sampled at 0.53R by the structural diagram shown in FIG. 2 when the pile top is eccentrically knocked at 0.53R of any radius under the conditions of longitudinal wave velocity of concrete 4050m/s, Poisson's ratio of 0.28, pile diameter of 2.9m, pile length of 25m and load pulse width of 1.6 ms. Where 0.53R is the result of calculation in which the Poisson ratio of 0.28 is substituted into (0.67-0.5 upsilon) R.
Description of the main element symbols:
100-solid section circular foundation piles; 200-vibration exciting device (force hammer or force rod);
300-information acquisition devices (probes or sensors); 400-information processing device (low strain detector with dual speed mode, single speed mode in the alternative).
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the low-strain dual-speed signal detection method of a solid pile under eccentric knock of a building of the present invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
The following detailed description of embodiments of the invention refers to the accompanying drawings.
Example 1
Fig. 1 is a schematic flow chart of a low-strain double-speed signal average detection method for a solid pile of a building according to the present invention. The low-strain double-speed signal average detection method of the building solid pile is applied to a building solid pile body, and comprises the following steps:
in step S11, a knock point is set on the top surface of the solid pile body of the building.
Specifically, the solid pile of the building is a solid circular foundation pile, the knocking action is vertical knocking through a force hammer or a force rod, and a knocking point can be located at any position of the surface of the pile top, including the pile center.
In one embodiment of the invention, the solid circular foundation pile body of the building is provided with a pile body. The strike point is located at 0.75R of the pile top surface (see fig. 3).
In one embodiment of the invention, the solid circular foundation pile body of the building is provided with a pile body. The strike points are located at 0R (pile center), 0.25R, 0.55R, 0.75R (see fig. 4) of the pile top surface.
It is understood that the solid pile of the building can be in other shapes besides the circular pile body, such as a square pile and other polygonal solid piles, that is, the building solid pile body can be detected by using the low-strain double-speed signal average detection method of the invention.
In step S12, under the condition that the poisson ratio of the pile body concrete is known, two signal acquisition devices are installed on the pile top surface of the solid pile of the building at (0.67-0.5 v) R positions on two radii of 45 ° and 135 ° with respect to the radius of the knocking point, wherein v is the poisson ratio of the pile body concrete, and R is the radius of the foundation pile.
Under the condition that the Poisson ratio of the pile body concrete is unknown, two signal acquisition devices are arranged at 2/3 positions of the radii of the reinforcement cages on the two radii; namely, two signal acquisition devices are arranged at 2/3 positions of the radius of the reinforcement cage on the top surface of the solid pile of the building, wherein the radius of the reinforcement cage is 45 degrees and 135 degrees with the radius of a knocking point, and the two signal acquisition devices are used as measuring points for the solid pile body of the building.
In particular, the signal acquisition device is a probe or a sensor. The signal acquisition device is adhered to the top surface of the solid pile of the building through adhesive substances such as glue, butter or plasticine. Under the condition that the Poisson ratio of the concrete of the pile body is known, two signal acquisition devices are arranged on the surface of the pile top of the solid pile of the building at the position (0.67-0.5 upsilon) R on two radiuses which form an angle of 45 degrees and an angle of 135 degrees with the radius of a knocking point, and are used as measuring points for the pile body of the solid pile of the building, wherein upsilon is the Poisson ratio of the concrete of the pile body, and R is the radius of the foundation pile. Wherein, (0.67-0.5 upsilon) R is an empirical calculation expression obtained by a large amount of calculations of the pile-soil model under the conditions of changing materials and geometric parameters, and actual engineering verification shows that the calculation formula has a good application effect. In addition, under the condition that the Poisson ratio of the concrete of the pile body is unknown, two signal acquisition devices are arranged at the position 2/3 of the radius of the reinforcement cage on the two radii, because the variation range of the Poisson ratio of the common concrete is about 0.1-0.35, the variation range of (0.67-0.5 upsilon) R is 0.5R-0.62R, and the variation range is actually closer to 2/3 of the radius of the reinforcement cage in consideration of the thickness of the concrete protection layer of the reinforcement cage. Therefore, under the condition that the Poisson ratio of the pile body concrete is unknown, two signal acquisition devices are arranged at 2/3 of the radius of the reinforcement cage on two radii of 45 degrees and 135 degrees with the radius of the knocking point.
In step S13, when a tapping motion at a tapping point is received, a point signal from each signal acquisition device is acquired and a two-speed test curve including each point signal is obtained at the same time;
specifically, the information processing device connected to the signal acquisition device and processing the signal acquired by the signal acquisition device is a low-strain detector with a dual-speed mode, such as a dual-channel low-strain detector. In the low-strain double-speed signal average detection method for the solid pile of the building, because the distances between two signal acquisition devices and a knocking point are different, in order to ensure the accuracy of the time difference of head wave incidence and the phase difference of interference signals between all measuring points, a low-strain detector with a double-speed mode is required to be used, and simultaneous sampling is carried out in the double-speed mode.
When a knocking action at a knocking point is received, the low-strain detector is used for simultaneously acquiring the measuring point signals of the two signal acquisition devices and obtaining corresponding double-speed test curves, and multiple times of knocking are used for acquiring multiple double-speed signals. When signal storage is carried out, a plurality of double-speed signals are averaged into a single double-speed signal, namely, when the signal is stored, the instrument averages the signals according to the channel (or sensor) unit, in other words, when the signal is stored, the instrument automatically averages the signals obtained by the same probe (or measuring point) under multiple knocks, and the aim is to verify the repeatability and stability of the signals and eliminate secondary interference or man-made interference.
In step S14, averaging the double speed curves to obtain a detection result of the solid pile body of the building;
specifically, step S14 specifically includes: and carrying out signal averaging on the double-speed test curve containing the signals of the measuring points acquired by the information processing device to generate a single speed curve. In an actual application scenario, two curves in the dual-speed signal may be averaged on a signal processing interface of the low-strain detector of the information processing apparatus, or the dual-speed signal may be introduced into signal analysis software matched with the low-strain detector to perform signal averaging, or may be derived into other data processing software to perform averaging. The result of the averaging is an averaged single speed profile.
The low-strain double-speed signal average detection method of the building solid pile comprises the steps of knocking at any point on the pile top surface of the building solid pile, collecting double-speed signal curves of two corresponding specific measuring points on the pile top surface, and averaging to obtain a single signal curve. Three-dimensional interference signals generated in a knocking area and eccentric moment shear waves propagated along the pile body stand column are eliminated through signal averaging, so that the selection range of knocking points is remarkably expanded, and the integrity of the pile body of the solid pile body of the building can be judged more accurately.
Example 2
Fig. 2 is a schematic structural diagram of a low-strain double-speed signal average detection method for a solid pile of a building according to the present invention. In this embodiment, the solid pile of the building is a solid circular foundation pile.
The vibration excitation device 200 generates eccentric knocking action at any point of the pile top surface of the solid pile 100, and under the condition that the pile body concrete poisson ratio is unknown, two signal acquisition devices 300 are arranged on the pile top surface of the building solid pile 100 at the positions (0.67-0.5 upsilon) R on two radiuses which form an angle of 45 degrees and an angle of 135 degrees with the radius of the knocking point, wherein the upsilon is the pile body concrete poisson ratio, and R is the radius of a foundation pile. Under the condition that the Poisson ratio of the pile body concrete is known, two signal acquisition devices are arranged at the position 2/3 of the radius of the reinforcement cage on the two radii; the information processing apparatus 400 is a low strain detector having a dual speed mode, and the test mode is the dual speed mode.
When the vibration excitation device 200 generates a knocking action on the pile top surface of the solid pile 100, a double-speed test curve containing two measuring point signals can be obtained through the sensor and the low-strain detector. When the vibration excitation device produces knocking action again at the same point, a second double-speed signal containing two speed curves is obtained, multiple times of knocking are carried out to acquire multiple double-speed signals, and when the signals are stored, the signals are averaged by the instrument according to a channel (or a sensor) as a unit, so that a double-speed signal containing two test curves is obtained. Subsequently, two curves in the double-speed signal are averaged on a signal processing interface of the low-strain detector of the information processing device, or the double-speed signal is led into signal analysis software matched with the low-strain detector for signal averaging, or can be led into other data processing software for averaging. The result of the averaging is an averaged single speed profile.
Referring to fig. 3, fig. 3 is a schematic diagram of the effect of the time curve before and after the low-strain dual-speed signal sampled at 0.53R on the radius of 45 ° and 135 ° from the knocking point is knocked at 0.75R on any radius of the pile top surface under the conditions of the concrete longitudinal wave velocity of 4050m/s, the poisson ratio of 0.28, the pile diameter of 2.9m, the pile length of 25m, and the load pulse width of 1.6ms in the structural diagram shown in fig. 2. Where 0.53R is a sampling position obtained by substituting a poisson ratio of 0.28 into (0.67-0.5 ν) R, and the average signal is a signal obtained by averaging two single-point signals corresponding to 0.53R on radii of 45 ° and 135 ° in the low-strain dual-velocity signal, where "averaging" specifically means averaging numerical values (vertical velocity values) on the ordinate axis of two single-channel (single-point) signals corresponding to the same time on the abscissa axis (time axis or pile length).
Fig. 3 shows that after the signals at two measuring points of 45 ° and 135 ° from the knock point are averaged, the three-dimensional interference signal of the averaged signal is significantly reduced and the eccentric shear wave at the rear part of the signal is eliminated, so that the interference signal in the single-channel (single-point) signal can be significantly eliminated by the double-speed averaging method proposed by this patent, thereby helping to judge the integrity of the solid pile body of the building more accurately.
Referring to fig. 4, fig. 4 is a schematic diagram of the structure shown in fig. 2, which is a comparison diagram of time-course curves of low-strain dual-speed average signals sampled at 0.53R on a radius of 45 ° and 135 ° from a radius of a knocking point when the pile is knocked at 0R, 0.25R, 0.55R and 0.75R of any radius of the pile top surface under the conditions of a longitudinal wave velocity of concrete 4050m/s, a poisson ratio of 0.28, a pile diameter of 2.9m, a pile length of 25m and a load pulse width of 1.6 ms; note that 0.53R is the sampling position obtained by substituting a Poisson ratio of 0.28 into (0.67-0.5 upsilon) R. Fig. 4 shows that, according to the low-strain double-speed signal average detection method for the solid pile of the building, when the position of the knocking point is changed, the difference of time-course curves of double-speed average signals is small, and the test effects are approximately consistent. Therefore, the low-strain double-speed signal average detection method for the solid pile of the building provided by the invention can remarkably enlarge the selection range of the knocking points.
The principle of the low-strain double-speed signal average detection method of the solid pile of the building provided by the invention is as follows: when the solid pile body of the building is knocked on the top surface of the solid pile body, longitudinal waves propagating along the pile body are generated in the solid pile body, and three-dimensional interference waves and eccentric moment shear waves which are distributed in an anti-symmetric mode exist on two sides of a vertical section where the diameter of the solid pile body forms an included angle of 90 degrees with the radius of a vibration excitation point. When the signals of two measuring points at specific positions on the radius of 45 degrees and 135 degrees with the radius of the knocking point are simultaneously collected and averaged, the influence of the two measuring points can be eliminated most obviously. The explanation from the angle of pile body vibration is that knocking on the pile body surface of the solid pile of the building generates not only an axisymmetric vibration mode but also a non-axisymmetric vibration mode. When signals at specific positions on the radius of 45 degrees and 135 degrees with the radius of the knocking point are collected and averaged at the same time, the influence of the non-axisymmetric mode shape can be eliminated most obviously.
FIG. 5 is a comparison graph of time-course curves of low-strain double-speed average signals sampled at 0.53R on the radius of 45 degrees and 135 degrees from the radius of a knocking point when the low-strain double-speed average signal of a solid pile of a building is knocked at 0.75R on the arbitrary radius of the top surface of the pile under the conditions of the longitudinal wave velocity of concrete 4050m/s, the Poisson ratio of 0.28, the pile diameter of 2.9m, the pile length of 25m and the load pulse width of 1.6ms, and sampled at the radius of 2/3 degrees from the center of the pile when the low-strain double-speed average signal is knocked at the midpoint of the top surface of the pile in the prior art. Fig. 5 shows that the interference signal in the proposed two-speed averaged signal is significantly reduced compared to the sampling scheme specified by the prior art method.
In the structural schematic diagram of the low-strain double-speed signal average detection method for the solid pile of the building shown in fig. 2 of the present invention, the structure is symmetrical about the vertical section where the connecting line between the knocking point and the middle point of the pile is located, so the detection results of the scheme shown in fig. 2 are consistent with those of the scheme shown in fig. 6, that is, fig. 6 is an equivalent schematic diagram of the structural schematic diagram shown in fig. 2, and relevant contents are not repeated here.
In addition, as the structure is symmetrical with the vertical section where the connecting line of the knocking point and the middle point of the pile is located, the two measuring points of the structural schematic diagram shown in fig. 2 and the equivalent schematic diagram shown in fig. 6 can be further mirrored simultaneously along the vertical section passing through the diameter where the knocking point is located, and the test result obtained by combining the mirrored measuring points is equivalent to that of fig. 2 and 6. Therefore, in actual work, the arrangement of the measuring points corresponding to the knocking at any point of the top surface of the solid pile is 4 combinations, namely the measuring point arrangement combination shown in fig. 2 and fig. 6 and the measuring point arrangement combination after the two are mirrored.
Example 3
Fig. 7 is a schematic structural diagram of an alternative low-strain double-speed signal average detection method for a solid pile of a building. In this embodiment, the solid pile of the building is a solid section circular pile. The method specifically comprises the following steps:
under the condition that the Poisson ratio of the pile body concrete is known, the vibration excitation device 200 generates an eccentric knocking action at a position (0.67-0.5 upsilon) R on any radius of the pile top surface of the solid pile 100 of the building, wherein upsilon is the Poisson ratio of the pile body concrete, and R is the radius of a foundation pile; under the condition that the Poisson ratio of the pile body concrete is unknown, the vibration excitation device 200 generates eccentric knocking action at the position 2/3 of the radius of the reinforcement cage on any radius of the pile top surface of the solid pile 100 of the building. On the diameter of the pile top surface of the solid pile 100 of the building, which is perpendicular to the radius of the knocking point, within the range of 0.15R from the left and right of the center of the pile respectively and within the range of 0.3R in total, at least one signal acquisition device 300 is arranged as a measuring point for the pile body of the solid pile of the building; the signal acquisition device 300 is connected to an information processing device 400, and the information processing device 400 is a low strain detector and adopts a single speed mode.
The specific tapping and sampling steps are the same as those of the conventional method, and are not described herein again.
Referring to fig. 8, fig. 8 is a schematic diagram of an alternative structure shown in fig. 7, which is a comparison diagram of time-course curves of low-strain signals sampled at 0R (pile midpoint), 0.05R, 0.1R, and 0.15R from the pile midpoint on a diameter perpendicular to a radius of a knocking point when the knocking is performed at 0.53R of any radius of the pile top surface under the conditions of a concrete longitudinal wave velocity of 4050m/s, a poisson ratio of 0.28, a pile diameter of 2.9m, a pile length of 25m, and a load pulse width of 1.6 ms; wherein R is a radius, and 0.53R is a knocking position obtained by substituting a Poisson ratio of 0.28 into (0.67-0.5 upsilon) R; fig. 8 shows that the alternative of fig. 8 provided by the present invention has approximately consistent test results when the signals received within 0.15R of the diameter perpendicular to the radius of the strike point are from the center of the pile and from the left to the right of the pile. Wherein R is the radius of the foundation pile.
Referring to fig. 9, fig. 9 is a comparison graph of the time course curve of the signal collected at the midpoint of the pile by eccentric tapping at 0.53R of any radius of the pile top under the conditions of the concrete longitudinal wave velocity of 4050m/s, the poisson ratio of 0.28, the pile diameter of 2.9m, the pile length of 25m and the load pulse width of 1.6ms, and the dual-speed average signal sampled at 0.53R of the structural diagram shown in fig. 2. Where 0.53R is the result of calculation in which the Poisson ratio of 0.28 is substituted into (0.67-0.5 upsilon) R.
Fig. 9 shows that the test effect of the double-speed averaging method and the alternative thereof proposed by the invention is similar, but the sampling effect of the double-speed averaging method is slightly better than that of the alternative.
The low-strain double-speed signal average detection method of the building solid pile comprises the steps of knocking at any point on the pile top surface of the building solid pile, collecting double-speed signal curves of two corresponding specific measuring points on the pile top surface, and averaging to obtain a single signal curve. Three-dimensional interference signals generated in a knocking area and eccentric moment shear waves propagated along the pile body stand column are eliminated through signal averaging, so that the pile body structure quality of the building pile body and the integrity of the pile bottom can be judged more accurately.
It should be noted that the angles of 45 ° and 135 ° between the signal acquisition point and the tapping point in the present invention allow a certain range of offset, the position of the signal acquisition point on the radius allows a certain range of offset, and the tapping point position given by the alternative allows a certain range of offset.
The low-strain double-speed signal average detection method for the building solid pile mainly aims at the solid circular pile, but is also suitable for square and polygonal solid piles, namely, the building solid pile detected by the low-strain double-speed signal average detection method belongs to the concept of the invention. For other examples, which are not given, the apparatus provided by the present invention is the same, and the implementation principle and the technical effect thereof are similar to those of the foregoing method embodiments, and for the sake of brief description, the method embodiments are not mentioned in part, and reference may be made to the corresponding contents in the foregoing method embodiments.
The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
In the several embodiments provided in the present application, it should be understood that the disclosed method, system, and apparatus may be implemented in other ways. The above-described apparatus embodiments are merely illustrative, and for example, the division of the module is merely a logical division, and there may be other divisions in actual implementation, and for example, a plurality of modules or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection of devices or units through some communication interfaces, and may be in an electrical, mechanical or other form.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (1)
1. The method for sampling the low-strain eccentric knocking single points of the foundation piles is applied to solid circular piles of buildings and is characterized by comprising the following steps of:
under the condition that the Poisson ratio of the pile body concrete is known, an excitation device generates eccentric knocking action at a position (0.67-0.5 upsilon) R on any radius of the pile top surface of the solid circular pile of the building, wherein upsilon is the Poisson ratio of the pile body concrete, and R is the radius of a foundation pile; under the condition that the Poisson ratio of the pile body concrete is unknown, the vibration excitation device generates eccentric knocking action at the position 2/3 of the radius of the reinforcement cage on any radius of the pile top surface of the solid circular pile of the building;
on the diameter of the pile top surface of the solid circular pile of the building, which is vertical to the radius of the knocking point, within the range of 0.15R from the left side to the right side of the pile center and within the range of 0.3R in total length, at least one signal acquisition device is arranged as a measuring point for the pile body of the solid circular pile of the building; the signal acquisition device is connected with the information processing device, the information processing device is a low-strain detector, a single-speed mode is adopted, and the specific steps of knocking and sampling are consistent with those of the existing method.
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| CN201610717737.4A CN106320396B (en) | 2016-08-24 | 2016-08-24 | The low strain dynamic two-speed signal averaging detection method of building solid pile |
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| CN107142977B (en) * | 2017-07-10 | 2018-10-09 | 荣垂强 | Low strain dynamic two-speed signal averaging detection method under the percussion of building foundation center |
| CN107190789B (en) * | 2017-07-10 | 2018-07-13 | 荣垂强 | A kind of load pulsewidth selection method of Low Strain Dynamic Testing of Piles |
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| CN106320396B (en) | 2018-09-14 |
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