Pile body torsion excitation device and pile body quality detection method

Abstract

The invention discloses a pile body torsion excitation device and a pile body quality detection method, and the pile body torsion excitation device comprises a load transmission mechanism which comprises two load-bearing pieces, the two load-bearing pieces are symmetrically fixed on the two sides of a pile body relative to the axis of a pile foundation and are attached to the pile body, and the two load-bearing pieces are provided with annular rails; the horizontal torsion mechanism comprises two impact bodies and a horizontally-arranged circular ring, the circular ring penetrates through the two annular rails to surround the periphery of the pile foundation, the circular ring is configured to rotate in the horizontal circumferential direction along the annular rails, and the two impact bodies are installed on the circular ring and located on the two sides of the load-bearing piece correspondingly; and the two impact bodies are configured to be allowed to slide on the circular ring when the circular ring does not rotate, and are also configured to be locked with the circular ring when the circular ring rotates, so that the impact bodies synchronously rotate along with the circular ring, and the two impact bodies are driven to synchronously impact the load-bearing surfaces of the corresponding load-bearing parts through the rotation of the circular ring. Symmetrical torsional excitation is generated on the pile body, and meanwhile the method is easier to implement and convenient to operate on site.

Description

Technical Field

[0001] The present invention relates to the technical field of pile foundation detection, and in particular to a pile body torsional excitation device and a pile body quality detection method. Background Art

[0002] Pile foundations are widely used foundation forms in industrial and civil buildings, and they have good adaptability to most geological and environmental conditions. However, since pile foundations generally need to be formed on-site by drilling holes and pouring concrete to form piles, or prefabricated in factories and then driven or pressed into the ground on-site, complex factors such as construction technology and strata may cause pile body defects. Moreover, during the service life of pile foundations, due to the continuous action of environmental loads, especially extreme loads, pile body defects may also occur. If these defects are hidden below the mud surface, it is very difficult to directly detect them. At this time, it is necessary to use detection techniques for hidden pile body defects, such as non-destructive testing methods like low strain, high strain, cross-hole ultrasonic testing, or destructive testing methods like drilling. However, for some defect characteristics, existing technical means are not applicable. For example, the defects generated during the driving of PHC piles are mainly vertical or inclined cracks. Generally, common low strain and high strain detections are difficult to apply. Among them, for the depth range above the mud surface and within the corresponding depth range where the PHC pile is not filled with soil layer, methods such as in-hole imaging and water filling can still be used for detection. However, for the depth range below the mud surface and where the PHC pile is filled with soil layer, the above methods are not applicable.

[0003] Theoretically, the one-dimensional longitudinal wave of a rod on which the existing low strain detection is based is not sensitive to hidden vertical or inclined cracks in the pile body, while the one-dimensional torsional wave of a rod is more sensitive to such cracks. However, at present, torsional waves are generally difficult to apply in actual engineering detections. The main reason is that relatively speaking, the traditional low strain detection is easily achieved by vertically hammering the pile top for excitation, while the realization of torsional excitation lacks a suitable and simple on-site operation method. Unilateral circumferential excitation simultaneously excites the horizontal vibration and torsional excitation of the pile foundation, and the velocity amplitude values of these two waves are quite similar. It is difficult to separate them after wave detection, resulting in difficulty in analyzing the reflected wave signals. Therefore, it is of important engineering application value to propose a simple device suitable for on-site operation and realizing symmetric torsional excitation.

[0004] On the other hand, the above-mentioned pile top excitation is only applicable to the working condition where the pile top is a free end. For in-service pile foundations, there is an upper structure at the pile top, and it is impossible to achieve free-end excitation at the pile top. For the detection of hidden defects in in-service pile foundations, there are mainly the double-velocity method, the cross-hole transmission method, and the frequency response function method at present. Among them: The cross-hole transmission method requires drilling holes on the side of the pile, and the implementation cost is relatively high, and it is difficult to implement under the restriction of upper structures such as wharf panels; The frequency response function method uses vertical excitation on the side of the pile, picks up the axial strain and acceleration of a certain cross-section below the excitation plane, and calculates the velocity admittance in the frequency domain and then converts it into the velocity time history curve in the time domain. Since this method requires picking up the axial strain of the pile body, the requirement for the vertical excitation force is relatively high, far beyond what can be achieved by the hammering energy of general low-strain tests. Therefore, it is very difficult to operate in the restricted space under the upper structure, such as below the wharf panel; The double-velocity method uses vertical excitation on the side of the pile, picks up the velocity time history curves of two interfaces below the excitation plane, and obtains the upward velocity wave that eliminates the influence of the upper structure within a certain time period through traveling wave decomposition, so as to identify the hidden defects in the lower part of the pile body. Generally speaking, the double-velocity method is theoretically feasible and relatively easy to operate. However, in current practical applications, excitation is generally carried out on one side of the pile side, resulting in a lateral swing with a comparable magnitude while the pile foundation undergoes vertical vibration. The velocity time history curve picked up is actually a superposition of vertical and lateral vibrations, and it is difficult to separate them, ultimately affecting the correct analysis of defects. In order to achieve symmetric excitation of the pile body, it is necessary to propose a pile-side symmetric excitation method that is easier to implement and convenient for on-site operation, as well as a detection and analysis method for hidden defects in in-service pile foundations, which has important value for achieving accurate and low-cost detection and evaluation of in-service pile foundations. Summary of the Invention

[0005] Aiming at the defects existing in the above prior art, one aspect of the present invention provides a pile body torsional excitation device, which can generate symmetric torsional excitation on the pile body and is easier to implement and convenient for on-site operation at the same time.

[0006] One aspect of the present invention is realized by adopting the following technical solutions:

[0007] A pile body torsional excitation device, comprising:

[0008] A load transfer mechanism, including two load-receiving members, which are symmetrically fixed on both sides of the pile body with respect to the axis of the pile foundation and are in contact with the pile body, and the vertical centerlines of the two load-receiving members are in the same plane as the axis of the pile foundation. Both load-receiving members are provided with annular tracks;

[0009] The horizontal torsion mechanism includes two impact bodies and a horizontally arranged ring. The inner diameter of the ring is greater than the outer diameter of the pile foundation. The ring passes through two annular tracks to surround the outer periphery of the pile foundation. The ring is supported by the annular tracks of the load-receiving members. The ring is configured to be rotatable horizontally circumferentially along the annular tracks. The two impact bodies are mounted on the ring and are respectively located on both sides of the load-receiving members. The two impact bodies are configured to allow sliding on the ring when the ring does not rotate. The two impact bodies are further configured to lock with the ring when the ring rotates, so as to achieve synchronous rotation of the impact bodies following the ring, and drive the two impact bodies to synchronously impact the load-receiving surfaces of the corresponding load-receiving members through the rotation of the ring.

[0010] Further, one of the load-receiving members has a load-receiving surface A, and the other load-receiving member has a load-receiving surface B. The load-receiving surface A and the load-receiving surface B are in the same plane, and this plane passes through the axis of the pile foundation.

[0011] Further, both the load-receiving surface A and the load-receiving surface B have magnetism. After the two impact bodies impact the corresponding load-receiving surface A and load-receiving surface B, they are adsorbed on the corresponding load-receiving members.

[0012] Further, the load transfer mechanism further includes a fixing member for fixing the load-receiving member on the outside of the pile foundation. Fixing holes are respectively provided on the upper and lower sides of the vertical center line of the load-receiving member. The fixing member passes through the fixing holes and is fixed to the pile foundation.

[0013] Further, a track groove penetrating two opposite side surfaces of the load-receiving member is provided inside the load-receiving member. A plurality of support recesses are installed in the track groove. Each support recess has an arc-shaped groove and a ball provided in the arc-shaped groove. The arc-shaped grooves of the plurality of support recesses are combined into an arc-shaped track. The ring penetrates into the arc-shaped track from the opening of the track groove, and the ring is supported by the arc-shaped grooves.

[0014] Further, the ring is composed of two semi-rings. Arc-shaped slots and arc-shaped insertion rods are provided at both ends of the two semi-rings. The diameter of the arc-shaped insertion rod is smaller than the diameter of the semi-ring. The two ends of the two semi-rings are connected together by a way of mutual insertion through the arc-shaped slots and arc-shaped insertion rods.

[0015] Further, the horizontal torsion mechanism further includes a coupling member for tightly connecting the arc-shaped slot and the arc-shaped insertion rod. Corresponding connection holes for the coupling member to pass through are provided in the arc-shaped slot and the arc-shaped insertion rod. The cross-sectional shape of the connection hole of the arc-shaped slot is a conical structure. The coupling member has a conical end and a conical end cap adapted to the conical structure.

[0016] Further, the horizontal torsion mechanism further includes an adjusting member. The impact body is provided with an arc groove and an adjusting hole communicating with the arc groove. The circular ring movably passes through the arc groove. After passing through the adjusting hole, the adjusting member can abut against the outer wall of the circular ring in the arc groove to lock the impact body and the circular ring. After the adjusting member disengages from the adjusting hole, the impact body slides on the circular ring.

[0017] The second aspect of the present invention provides a method for detecting the quality of a pile body, which is convenient for detecting defects in the pile body at different depths.

[0018] The second aspect of the present invention is realized by adopting the following technical solutions:

[0019] A method for detecting the quality of a pile body includes the above-mentioned pile body torsion excitation device and further includes the following steps:

[0020] (1) Arrange two acceleration sensors at intervals along the longitudinal direction on the outer wall of the pile body;

[0021] (2) Install the torsion excitation device on the pile body, ensure that the vertical centerlines of the two loading members are in the same plane as the axis of the pile foundation. Then slide the two impact bodies so that the two impact bodies synchronously and closely adhere to the loading surfaces of the corresponding loading members. Then lock the impact bodies and the circular ring. Then rotate the circular ring to pull the distance between the two impact bodies and the loading members. Then push the circular ring in the opposite direction so that the two impact bodies respectively and synchronously impact the loading surfaces of the corresponding loading members. After the two loading blocks are subjected to the excitation force, stress waves are generated, and the stress waves propagate along the pile body;

[0022] (3) The stress waves reach the positions where the two acceleration sensors are located successively and generate acceleration responses. The two acceleration sensors successively collect the circumferential acceleration time history curves. By performing time integration on the circumferential acceleration time history curves, the circumferential velocity time history curves at the positions where the two acceleration sensors are located are obtained. Qualitative evaluation of the change in pile body impedance and the situation at the pile end is carried out through the circumferential velocity to further realize the evaluation of the defects and positions of the pile body.

[0023] Further, the two acceleration sensors are on the same straight line and this straight line is perpendicular to the connecting line of the vertical centerlines of the two loading members.

[0024] Compared with the prior art, the beneficial effects of the present invention at least include:

[0025] The present invention applies torsional excitation to two load-bearing members through two impact bodies, and the torsional excitation is transmitted to the pile body by the load-bearing members, so that symmetric torsional excitation can be generated on the pile body. The vertical centerlines of the two load-bearing members and the axis of the pile foundation are in the same plane, ensuring that the two impact bodies synchronously impact the corresponding load-bearing members, achieving symmetric excitation of the pile body and ensuring the accuracy of the detection data. In addition, by installing two impact bodies on the ring, the two impact bodies can be driven to rotate synchronously by rotating the ring, realizing the synchronous impact of the two impact bodies on the corresponding load-bearing members. The method of applying the excitation force is simple. Therefore, the device of the present invention has the advantages of simple operation, convenient implementation, low measurement cost, and high measurement accuracy. In the traditional single-sided excitation on the side of the pile, it causes a relatively large lateral swing while the pile foundation undergoes vertical vibration. The velocity time history curve picked up is actually the superposition of vertical and lateral vibrations, and it is difficult to separate them, ultimately affecting the correct analysis of defects. However, in the present invention, by symmetrically arranging two load-bearing members on both sides of the pile body, and then driving two impact bodies to synchronously impact the two load-bearing members through the ring of the horizontal torsion mechanism, by means of synchronous impact, it is ensured that only one wave signal is generated on the pile body. In this way, the picked-up velocity time history curve is more accurate, improving the correct analysis of pile foundation defects, which has important value for accurately and low-cost detection and evaluation of in-service pile foundations. Therefore, the torsional excitation device of the present invention has the advantages of being easier to implement and convenient for on-site operation compared with the traditional single-sided excitation on the side of the pile, and the detection is accurate and the detection cost is low. Description of the Drawings

[0026] Figure 1 is a schematic diagram of the pile body torsional excitation device according to an embodiment of the present invention;

[0027] Figure 2 is a cross-sectional view of the torsional excitation device according to an embodiment of the present invention;

[0028] Figure 3 is a schematic diagram of the load transmission mechanism according to an embodiment of the present invention;

[0029] Figure 4 is one of the cross-sectional views of the load-bearing member according to an embodiment of the present invention;

[0030] Figure 5 is the other cross-sectional view of the load-bearing member according to an embodiment of the present invention;

[0031] Figure 6 is a schematic diagram of the horizontal torsion mechanism according to an embodiment of the present invention;

[0032] Figure 7 is a cross-sectional view of the assembly of the impact body and the ring according to an embodiment of the present invention;

[0033] Figure 8 is a top view of the horizontal torsion mechanism according to an embodiment of the present invention;

[0034] Figure 9 It is one of the schematic diagrams of installing the torsional excitation device according to the embodiment of the present invention on the pile body;

[0035] Figure 10 It is the second schematic diagram of installing the torsional excitation device according to the embodiment of the present invention on the pile body;

[0036] In the figure: 1. Pile foundation; 11. Pile body; 2. Torsional excitation device; 21. Load transfer mechanism; 210. Load-bearing member; 2101. Load-bearing surface A; 2102. Load-bearing surface B; 2103. Fixing hole; 2104. Track groove; 211. Ring track; 212. Fixing member; 213. Support concave block; 2130. Arc-shaped groove; 2231. Ball; 22. Horizontal torsion mechanism; 220. Impact body; 2201. Adjusting hole; 221. Ring; 2210. Arc-shaped slot; 2211. Arc-shaped insertion rod; 222. Combining member; 2220. Conical end; 2221. Conical end cap; 223. Adjusting member; 3. Upper acceleration sensor; 4. Lower acceleration sensor. Detailed implementation manners

[0037] Now, the exemplary embodiments will be described more comprehensively with reference to the accompanying drawings. However, the exemplary embodiments can be implemented in various forms and should not be construed as limited to the embodiments set forth herein; on the contrary, these embodiments are provided so that the present invention will be more comprehensive and complete, and the concept of the exemplary embodiments will be fully conveyed to those skilled in the art. The same reference numerals in the figures denote the same or similar structures, and thus their repeated description will be omitted.

[0038] The words expressing position and direction described in the present invention are all illustrated with reference to the accompanying drawings, but can be changed as needed, and all changes made are included in the protection scope of the present invention.

[0039] For the convenience of clearly describing the technical solutions of the embodiments of the present invention, as Figure 9 shown, three lines can be defined, namely the pile foundation axis Y1, the vertical center lines Y2 of the two load-bearing members 210, S1 is the position where the upper acceleration sensor 3 is located, S2 is the position where the lower acceleration sensor 4 is located, and L is the vertical distance between the upper acceleration sensor 3 and the lower acceleration sensor 4.

[0040] As Figures 1-8 shown, a pile body torsional excitation device 2 provided by the present invention includes:

[0041] A load transfer mechanism 21, including two load-bearing members 210, the two load-bearing members 210 are symmetrically fixed on both sides of the pile body 11 with respect to the axis of the pile foundation 1 and are in contact with the pile body 11, and the vertical center lines of the two load-bearing members 210 are in the same plane as the axis of the pile foundation 1, and both of the two load-bearing members 210 are provided with ring tracks 211;

[0042] The horizontal torsion mechanism 22 includes two impact bodies 220 and a horizontally arranged ring 221. The inner diameter of the ring 221 is larger than the outer diameter of the pile foundation 1. The ring 221 passes through two annular tracks 211 to surround the outer periphery of the pile foundation 1. The ring 221 is supported by the annular tracks 211 of the load receiving member 210. The ring 221 is configured to be rotatable horizontally circumferentially along the annular tracks 211. The two impact bodies 220 are mounted on the ring 221 and are respectively located on both sides of the load receiving member 210. The two impact bodies 220 are configured to allow sliding on the ring 221 when the ring 221 does not rotate. The two impact bodies 220 are further configured to be locked with the ring 221 when the ring 221 rotates, so as to realize the synchronous rotation of the impact bodies 220 following the ring 221. The rotation of the ring 221 drives the two impact bodies 220 to synchronously impact the load receiving surfaces of the corresponding load receiving members 210.

[0043] In this embodiment, torsional excitation is applied to the two load receiving members 210 through the two impact bodies 220, and the torsional excitation is transmitted to the pile shaft 11 by the load receiving members 210, so that symmetric torsional excitation can be generated on the pile shaft 11. The vertical center lines of the two load receiving members 210 and the axis of the pile foundation 1 are in the same plane, ensuring that the two impact bodies 220 synchronously impact the corresponding load receiving members 210, achieving symmetric excitation of the pile shaft 11 and ensuring the accuracy of the detection data. In addition, by installing two impact bodies 220 on the ring 221, by rotating the ring 221, the two impact bodies 220 can be driven to rotate synchronously, realizing the synchronous impact of the two impact bodies 220 on the corresponding load receiving members 210. The method of applying the excitation force is simple. Therefore, the device of the present invention has the advantages of simple operation, convenient implementation, low measurement cost and high measurement accuracy. In the traditional single-sided excitation on the side of the pile, when the pile foundation 1 vibrates vertically, a lateral swing with a comparable magnitude is generated at the same time. The actually picked-up velocity time history curve is actually the superposition of vertical and lateral vibrations, and it is difficult to separate, ultimately affecting the correct analysis of the defects. While in the present invention, by symmetrically arranging two load receiving members 210 on both sides of the pile shaft 11, and then driving the two impact bodies 220 to synchronously impact the two load receiving members 210 through the ring 221 of the horizontal torsion mechanism 22, by the way of synchronous impact, it is ensured that only one wave signal is generated on the pile shaft 11. The picked-up velocity time history curve is more accurate, improving the correct analysis of the defects of the pile foundation 1, which has important value for the accurate and low-cost detection and evaluation of the in-service pile foundation 1. Therefore, the torsional excitation device 2 of the present invention has the advantages of being easier to implement and more convenient for on-site operation than the traditional single-sided excitation on the side of the pile, and the detection is accurate and the detection cost is low.

[0044] Among them, the installation method of the torsional excitation device 2 of the present invention is as follows: If the pile foundation 1 is a straight pile, two loading members 210 are symmetrically placed on both sides of the pile foundation 1 close to the pile body 11. The vertical centerlines of the two loading members 210 and the axis of the pile foundation 1 are in the same plane, and the bottom surfaces of the two loading members 210 are in the same plane. Mark the fixed positions of the loading members 210 on the pile body 11; If the pile foundation 1 is an inclined pile, measure the slope of the pile foundation 1. Two loading members 210 are symmetrically placed on both sides of the pile foundation 1 close to the pile body 11 in an inclined manner. The vertical centerlines of the two loading members 210 and the axis of the pile foundation 1 are in the same plane, and the bottom surfaces of the two loading members 210 are in the same plane. Measure the slope of this plane and correct it with the slope of the pile foundation 1. After the correction is correct, mark the fixed positions of the loading members 210 on the pile body 11; Drill holes at the marked fixed positions, insert fixing members 212, and fix the load transfer mechanism 21 on both sides of the pile foundation 1; Pass two semi-circular rings 221 through two annular tracks 211 respectively. Connect the arc-shaped insertion rod 2211 of one semi-circular ring 221 with the arc-shaped slot 2210 of the other semi-circular ring 221. Then, pass two impact bodies 220 through the corresponding semi-circular rings 221 respectively. Fix the impact bodies 220 on the semi-circular rings 221 through adjusting members 223. Then, connect the arc-shaped slot 2210 of one semi-circular ring 221 with the arc-shaped insertion rod 2211 of the other semi-circular ring 221 and fix them with a coupling member 222 to form a complete ring 221. In this way, the installation of the torsional excitation device 2 on the pile body 11 can be completed.

[0045] Before the impact, release the locking of the adjusting member 223 on the impact body 220, slide the two impact bodies 220 so that one impact body 220 is close to the loading surface A2101 of one loading member 210, and the other impact body 220 is synchronously close to the loading surface B2102 of the other loading member 210. Then, lock the impact body 220 and the ring 221 through the adjusting member 223; Then rotate the ring 221 to increase the distance between the impact body 220 and the loading member 210, and then push the ring 221 in the opposite direction so that the two impact bodies 220 respectively and synchronously impact the loading surfaces B2102 and A2101 of the two loading members 210, so that the two loading members 210 are synchronously subjected to torsional excitation force.

[0046] As a preferred embodiment, one of the loading members 210 has a loading surface A2101, and the other loading member 210 has a loading surface B2102. The loading surface A2101 and the loading surface B2102 are in the same plane and this plane passes through the axis of the pile foundation 1. Through the above setting method, it is further ensured that the two impact bodies 220 synchronously impact the two loading members 210, thereby ensuring that the pile body 11 generates symmetric torsional excitation and the detection data is more accurate.

[0047] As a preferred embodiment, both the loading surface A2101 and the loading surface B2102 are magnetic. After the two impact bodies 220 impact the corresponding loading surface A2101 and loading surface B2102, they are adsorbed on the corresponding loading member 210. In this way, it is possible to prevent the impact body 220 from rebounding after impacting the loading member 210 and avoid the situation where the impact body 220 impacts the loading member 210 again.

[0048] As a preferred embodiment, the load transfer mechanism 21 further includes a fixing member 212 for fixing the loading member 210 to the outside of the pile foundation 1. Fixing holes 2103 are respectively provided on the upper and lower sides of the vertical center line of the loading member 210, and the fixing member 212 passes through the fixing holes 2103 and is fixed to the pile foundation 1.

[0049] In this embodiment, by providing the fixing holes 2103 in the loading member 210, it is convenient for the fixing member 212 to quickly fix the loading member 210 on the pile body 11, achieving the purpose of convenient installation. Among them, the fixing member 212 is preferably an expansion bolt, and the fixing hole 2103 is preferably a screw hole.

[0050] As a preferred embodiment, a track groove 2104 penetrating two opposite sides of the loading member 210 is provided inside the loading member 210. A plurality of support concave blocks 213 are installed in the track groove 2104. Each support concave block 213 has an arc-shaped groove 2130 and a ball 2231 provided in the arc-shaped groove 2130. The arc-shaped grooves 2130 of the plurality of support concave blocks 213 are combined into an arc-shaped track. The ring 221 penetrates into the arc-shaped track from the opening of the track groove 2104, and the ring 221 is supported by the arc-shaped groove 2130.

[0051] In this embodiment, by providing the track groove 2104 inside the loading member 210, the support concave blocks 213 are installed in the track groove 2104, and the ring 221 is supported by the support concave blocks 213 to rotate. At the same time, by contacting the ring 221 through the balls 2231, the smoothness of the rotation of the ring 221 is improved.

[0052] It should be noted that a plurality of support concave blocks 213 are provided on both the upper and lower inner walls of the track groove 2104, and the plurality of support concave blocks 213 are arranged at intervals along the extending direction of the track groove 2104. In this way, the arc-shaped grooves 2130 arranged up and down are combined into an arc-shaped track. By adopting the above design method, the stability of the rotation of the ring 221 can be improved, and the smoothness and stability of the rotation of the ring 221 can be ensured.

[0053] As a preferred embodiment, the circular ring 221 is composed of two semi-circular rings. Arc-shaped slots 2210 and arc-shaped insertion rods 2211 are provided at both ends of the two semi-circular rings. The diameter of the arc-shaped insertion rod 2211 is smaller than the diameter of the semi-circular ring. The two semi-circular rings are connected together by inserting and connecting through the arc-shaped slots 2210 and arc-shaped insertion rods 2211 at both ends respectively. Through the above connection method, it is convenient to pass the semi-circular ring through the arc-shaped track. After installing an impact body 220 on each of the two semi-circular rings, then inserting and connecting the two semi-circular rings, the rapid installation of the circular ring 221 and the impact body 220 can be quickly completed.

[0054] As a preferred embodiment, the horizontal torsion mechanism 22 further includes a coupling member 222 for tightly connecting the arc-shaped slot 2210 and the arc-shaped insertion rod 2211. Corresponding connection holes for the coupling member 222 to pass through are provided in the arc-shaped slot 2210 and the arc-shaped insertion rod 2211. The cross-sectional shape of the connection hole of the arc-shaped slot 2210 is a conical structure. The coupling member 222 has a conical end 2220 and a conical end cap 2221 adapted to the conical structure. By providing the coupling member 222 at the connection between the arc-shaped slot 2210 and the arc-shaped insertion rod 2211, the two semi-circular rings are tightly connected by the coupling member 222 to ensure reliable connection of the two semi-circular rings; the connection hole is in a conical structure. When the coupling member 222 is tightened, the conical surface of the connection hole deforms, which can prevent the coupling member 222 from loosening and avoid the situation that the coupling member 222 falls off from the connection hole, improving the reliability of the connection between the two semi-circular rings. At the same time, by using the conical end 2220 and the conical end cap 2221 provided at both ends of the connection hole, the connection hole can be effectively blocked, further preventing the coupling member 222 from loosening and achieving a better connection effect.

[0055] The coupling member 222 of this embodiment is preferably a coupling bolt, and the connection hole is preferably a bolt hole. The end of the coupling bolt is in a conical structure. After the screw of the coupling bolt passes through the connection hole, the coupling bolt is locked by a conical nut to prevent the coupling bolt from loosening.

[0056] As a preferred embodiment, the horizontal torsion mechanism 22 further includes an adjusting member 223. The impact body 220 is provided with an arc-shaped groove and an adjusting hole 2201 communicating with the arc-shaped groove. The circular ring 221 movably passes through the arc-shaped groove. After the adjusting member 223 passes through the adjusting hole 2201, it can abut against the outer wall of the circular ring 221 in the arc-shaped groove to lock the impact body 220 and the circular ring 221. When the adjusting member 223 disengages from the adjusting hole 2201, the impact body 220 slides on the circular ring 221.

[0057] In this embodiment, the locking and unlocking of the impact body 220 are realized through the adjusting member 223, which makes the operation more convenient and is also convenient for disassembly. Specifically, the adjusting member 223 of the present invention is preferably an adjusting bolt, and the adjusting bolt has a conical adjusting end. The adjusting hole 2201 has a conical surface adapted to the conical adjusting end. By using the deformation effect of the conical surface, the loosening of the adjusting bolt is avoided, and the situation that the impact body 220 slides when the ring 221 rotates is prevented.

[0058] The present invention also provides a method for detecting the quality of a pile body, which includes the above-mentioned pile body torsional excitation device 2 and further includes the following steps:

[0059] (1) Arrange two acceleration sensors at intervals along the longitudinal direction on the outer wall of the pile body 11.

[0060] (2) Symmetrically install the two loading members 210 of the torsional excitation device 2 on both sides of the pile body 11, ensure that the vertical centerlines of the two loading members 210 and the axis of the pile foundation 1 are in the same plane. Then slide the two impact bodies 220 so that the two impact bodies 220 are synchronously close to the loading surfaces of the corresponding loading members 210. Then lock the impact bodies 220 with the ring 221. Next, rotate the ring 221 to increase the distance between the two impact bodies 220 and the loading members 210. Then push the ring 221 in the opposite direction so that the two impact bodies 220 respectively and synchronously impact the loading surfaces of the corresponding loading members 210. After the two loading blocks are subjected to the excitation force, stress waves are generated, and the stress waves propagate along the pile body 11.

[0061] (3) The stress waves reach the positions where the two acceleration sensors are located successively and generate acceleration responses. The two acceleration sensors successively collect the circumferential acceleration time history curves. By performing time integration on the circumferential acceleration time history curves, the circumferential velocity time history curves at the positions where the two acceleration sensors are located are obtained. The impedance change of the pile body and the conditions of the pile end are qualitatively evaluated through the circumferential velocity, so as to further evaluate the defects and positions of the pile body 11.

[0062] In the present invention, with reference to Figures 9-10, by installing two symmetrically arranged load-bearing members 210 on the pile body 11, with the vertical centerlines of the two load-bearing members 210 in the same plane as the axis of the pile foundation 1, using the ring 221 to drive the two impact bodies 220 to synchronously impact the load-bearing surfaces of the corresponding load-bearing members 210, so that the two load-bearing members 210 are simultaneously subjected to torsional excitation, thus generating symmetric torsional excitation on the pile body 11, that is, only one stress wave is generated on the pile body 11. This stress wave is successively detected by two acceleration sensors to obtain the circumferential acceleration time history curves at the positions of the two acceleration sensors. By performing time integration on each circumferential acceleration time history curve, the circumferential velocity time history curve is obtained. By qualitatively evaluating the impedance change of the pile body 11 and the pile tip condition through the circumferential velocity, the defects and positions of the pile body 11 are qualitatively evaluated. This detection method is easier to implement and convenient for on-site operation, and has important value for realizing accurate and low-cost detection and evaluation of in-service pile foundations.

[0063] As a preferred embodiment, referring to Figure 9 , the two acceleration sensors are on the same straight line and this straight line is perpendicular to the connection line of the vertical centerlines of the two load-bearing members 210. In this way, the signal interference caused by the vibration of the load transfer mechanism 21 can be reduced, and the detection accuracy can be further improved.

[0064] The present invention provides a detection method for arranging two acceleration sensors on the pile body 11 for measurement, specifically as follows: The two acceleration sensors are respectively an upper acceleration sensor 3 and a lower acceleration sensor 4. The stress wave first arrives at the position of the upper acceleration sensor 3 and generates an acceleration response. By performing time integration on the circumferential acceleration time history curve collected by the upper acceleration sensor 3, the time history curve U(S 1 , t) of the circumferential velocity at the position of the upper acceleration sensor 3 can be obtained. This circumferential velocity is the superposition velocity of the upward wave and the downward wave; by performing time integration on the circumferential acceleration time history curve collected by the lower acceleration sensor 4, the time history curve U(S 2 , t) of the circumferential velocity at the position of the lower acceleration sensor 4 can be obtained. This circumferential velocity is the superposition velocity of the upward wave and the downward wave;

[0065] Among them, the calculation method of the downward wave velocity U↓(S 1 , t) of the upper acceleration sensor 3 is as follows:

[0066] U↓(S 1 , t) = U(S 1 , t) - U(S 2 , t - T) + U↓(S 1 , t - 2T)

[0067] The calculation method of the upward wave velocity U↑(S 1 , t) of the upper acceleration sensor 3 is as follows:

[0068] U↑(S 1 ,t) = U(S 1 ,t) - U↓(S 1 ,t)

[0069] Where: t is the time for the stress wave to propagate from S1 of the upper acceleration sensor 3 to S2 of the lower acceleration sensor 4, and the time t required for the propagation distance L is t = L / c, where c is the shear stress wave velocity of the pile foundation material, and L is the vertical distance between the upper acceleration sensor 3 and the lower acceleration sensor 4.

[0070] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention without departing from the principles and purposes of the present invention, and all such changes should fall within the protection scope of the claims of the present invention.

Claims

1. A pile body torsional vibration excitation device, characterized in that: include: The load transfer mechanism (21) comprises two load-bearing members (210), the two load-bearing members (210) are symmetrically fixed on both sides of the pile body (11) about the axis of the pile foundation (1) and fit the pile body (11), and the vertical center lines of the two load-bearing members (210) are in the same plane as the axis of the pile foundation (1), and the two load-bearing members (210) are both provided with an annular track (211); The horizontal torsion mechanism (22) comprises two impact bodies (220) and a horizontally arranged circular ring (221), wherein the inner diameter of the circular ring (221) is larger than the outer diameter of the pile foundation (1), the circular ring (221) passes through two circular tracks (211) to surround the outer circumference of the pile foundation (1), and the circular ring (221) is supported by the circular track (211) of the load-bearing member (210), and the circular ring (221) is configured to be rotatable in the horizontal circumferential direction along the circular track (211). The two impact bodies (220) are installed on the pile foundation (1). The two impact bodies (220) are respectively located on the circular ring (221) and on both sides of the load-bearing member (210). The two impact bodies (220) are configured to allow sliding on the circular ring (221) when the circular ring (221) is not rotating. The two impact bodies (220) are also configured to lock with the circular ring (221) when the circular ring (221) rotates, so that the impact bodies (220) rotate synchronously with the circular ring (221). The rotation of the circular ring (221) drives the two impact bodies (220) to synchronously impact the load-bearing surfaces of the corresponding load-bearing members (210).

2. The pile body torsional vibration excitation device according to claim 1, characterized in that: One of the load-bearing members (210) has a load-bearing surface A (2101), and the other load-bearing member (210) has a load-bearing surface B (2102). The load-bearing surface A (2101) and the load-bearing surface B (2102) are in the same plane and the plane passes through the axis of the pile foundation (1).

3. The pile body torsional vibration excitation device according to claim 2, characterized in that: The load-bearing surface A (2101) and the load-bearing surface B (2102) are both magnetic, and the two impact bodies (220) are adsorbed on the corresponding load-bearing parts (210) after impacting the corresponding load-bearing surfaces A (2101) and the load-bearing surfaces B (2102).

4. The pile body torsional vibration excitation device according to claim 1, characterized in that: The load transfer mechanism (21) further comprises a fixing member (212) for fixing the load-bearing member (210) on the outside of the pile foundation (1); fixing holes (2103) are respectively provided on the upper and lower sides of the vertical center line of the load-bearing member (210); and the fixing member (212) passes through the fixing holes (2103) and is fixed to the pile foundation (1).

5. The pile body torsional vibration excitation device according to claim 1, characterized in that: The load-bearing member (210) is provided with a track groove (2104) passing through two opposite sides of the load-bearing member (210), and a plurality of supporting recessed blocks (213) are installed in the track groove (2104), each of the supporting recessed blocks (213) having an arc-shaped groove (2130) and a ball (2231) arranged in the arc-shaped groove (2130), and the arc-shaped grooves (2130) of the plurality of supporting recessed blocks (213) are combined into an arc-shaped track, and the circular ring (221) penetrates into the arc-shaped track from an opening of the track groove (2104), and is supported by the arc-shaped groove (2130).

6. The pile body torsional vibration excitation device according to claim 1, characterized in that: The circular ring (221) is composed of two semicircular rings, and arc-shaped slots (2210) and arc-shaped insertion rods (2211) are provided at both ends of the two semicircular rings. The diameter of the arc-shaped insertion rod (2211) is smaller than the diameter of the semicircular rings. The two ends of the two semicircular rings are connected together by inserting the arc-shaped slots (2210) and the arc-shaped insertion rods (2211) into each other.

7. The pile body torsional vibration excitation device according to claim 6, characterized in that: The horizontal torsion mechanism (22) further comprises a coupling member (222) for fastening the arc-shaped slot (2210) and the arc-shaped insertion rod (2211), the arc-shaped slot (2210) and the arc-shaped insertion rod (2211) being provided with connection holes for the coupling member (222) to pass through, the cross-sectional shape of the connection holes of the arc-shaped slot (2210) being a conical structure, and the coupling member (222) having a conical end head (2220) and a conical end cap (2221) adapted to the conical structure.

8. The pile body torsional vibration excitation device according to claim 1, characterized in that: The horizontal twisting mechanism (22) further comprises an adjusting member (223); the impact body (220) is provided with an arc groove and an adjusting hole (2201) connected to the arc groove; the circular ring (221) movably passes through the arc groove; after the adjusting member (223) passes through the adjusting hole (2201), it can abut against the outer wall of the circular ring (221) in the arc groove to lock the impact body (220) and the circular ring (221); after the adjusting member (223) is separated from the adjusting hole (2201), the impact body (220) slides on the circular ring (221).

9. A pile body quality detection method, characterized in that: The pile body torsional vibration excitation device (2) according to any one of claims 1 to 8 further comprises the following steps: (1) two acceleration sensors are arranged at intervals along the longitudinal direction on the outer wall of the pile body (11); (2) installing the torsional vibration device (2) on the pile body (11) to ensure that the vertical center lines of the two load-bearing parts (210) and the axis of the pile foundation (1) are in the same plane, then sliding the two impact bodies (220) so that the two impact bodies (220) are synchronously close to the load-bearing surfaces of the corresponding load-bearing parts (210), then locking the impact bodies (220) and the ring (221), then rotating the ring (221) to increase the distance between the two impact bodies (220) and the load-bearing parts (210), and then pushing the ring (221) in the opposite direction so that the two impact bodies (220) respectively synchronously impact the load-bearing surfaces of the corresponding load-bearing parts (210), and the two load-bearing blocks generate stress waves after being subjected to the exciting force, and the stress waves propagate along the pile body (11); (3) The stress wave reaches the positions of the two acceleration sensors successively and generates acceleration responses. The two acceleration sensors successively collect circumferential acceleration time history curves. By time integrating the circumferential acceleration time history curves, circumferential velocity time history curves at the positions of the two acceleration sensors are obtained. The impedance change of the pile body (11) and the pile end condition are qualitatively evaluated by the circumferential velocity, so as to further achieve qualitative evaluation of the defects and positions of the pile body (11).

10. The pile body quality detection method according to claim 9, characterized in that: The two acceleration sensors are located on the same straight line, and the straight line is perpendicular to a connecting line of vertical center lines of the two load-bearing members (210).

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