A displacement test device and test method suitable for self-balancing test

Abstract

The invention discloses a displacement testing device and a testing method suitable for a self-balancing test. According to the invention, the bottom end of an upper displacement rod / wire is connected to a top displacement measuring point of a pile body reinforcement area to test the displacement of an upper pile body, the bottom end of a lower displacement rod / wire is connected to a bottom end of a pile body reinforcement area to test the displacement of an upper pile body, and the bottom end of a top displacement rod / wire is connected to a top displacement measuring point of a pile body to test the displacement of a pile top. Compared with the existing device, the position of the displacement measuring point is adjusted so that the displacement measurement is not affected by the output of a load box jack, thereby ensuring the accuracy of the displacement result. At the same time, the adjusted displacement measuring point avoids a local stress concentration area of ​​a self-balancing test, so that the displacement test result error of two displacement points at the same elevation and in the same direction does not exceed 30% of the mean value, which meets the provisions of the technical specification for building foundation pile detection.

Description

Technical Field

[0001] The invention relates to a displacement testing device and a testing method suitable for a self-balancing test, belonging to the technical field of a self-balancing static load test of a building pile foundation. Background Art

[0002] In past pile foundation self-balancing projects, bladder-type load boxes and ring-belt-type load boxes were more commonly used. In the domestic market, there are basically two types of jacks used for load boxes: plunger-type jacks and piston-type jacks. Both types of load boxes can achieve the purpose of smoothly turning over the pile body concrete, and the assembly process of the load box is unmatched by other load boxes.

[0003] At present, the displacement test devices for self-balancing tests are mainly the following: 1. The upper and lower displacement measuring points are arranged at the top and bottom of the capsule load box, and then led to the ground through the displacement wire; 2. On the upper and lower steel plates of the ring-type load box, they are welded and led to the ground through the displacement rod. The above displacement measuring point arrangements are not reasonable, because as long as the displacement measuring points are arranged near the jack, they are bound to be more or less affected by the output of the load box jack, thereby affecting the accuracy of the displacement results. At the same time, the above displacement measuring points do not avoid the local stress concentration area, so that the displacement test results of the two displacement points at the same elevation and in the same direction have an error of more than 30% of the mean, which does not meet the requirements of the technical specifications for building foundation pile detection. Summary of the invention

[0004] The invention provides a displacement testing device and a testing method suitable for a self-balancing test, which solve the problems disclosed in the background technology.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A displacement test device suitable for a self-balancing test, comprising an upper displacement rod / wire pair, a lower displacement rod / wire pair and a top displacement rod / wire pair;

[0007] The upper displacement rod / wire pair includes two upper displacement rods / wires arranged vertically and opposite to each other, the bottom ends of the upper displacement rods / wires are connected to the top displacement measuring points of the pile body reinforcement area to test the displacement of the upper pile body, and the upper displacement rod / wire pair and the central axis of the pile body are in the same plane;

[0008] The lower displacement rod / wire pair includes two lower displacement rods / wires arranged vertically and opposite to each other, the bottom ends of the lower displacement rods / wires are connected to the bottom displacement measuring points of the pile body reinforcement area to test the displacement of the lower pile body, and the lower displacement rod / wire pair and the central axis of the pile body are on the same plane;

[0009] The top displacement rod / wire pair includes two vertically arranged opposite top displacement rods / wires, the bottom ends of which are connected to the top displacement measuring points of the pile body to test the pile top displacement, and the top displacement rod / wire pair and the central axis of the pile body are in the same plane.

[0010] The part of the displacement rod / wire inside the pile body is passed through the protective tube.

[0011] The protective tube is a PPR tube or a steel casing.

[0012] A number of vertical main reinforcement bars are arranged on the inner side of the pile body reinforcement cage, and each protective tube is tied to a main reinforcement bar.

[0013] The length of the tied main reinforcement is equal to the length of the tied protective tube inside the pile body.

[0014] There is one pair of upper displacement rod / wire pair and one pair of lower displacement rod / wire pair, and the plane where the upper displacement rod / wire pair is located is perpendicular to the plane where the lower displacement rod / wire pair is located.

[0015] A testing method for a displacement testing device suitable for a self-balancing test, comprising:

[0016] Determine the top displacement measuring point of the pile reinforcement area, the bottom displacement measuring point of the pile reinforcement area, and the top displacement measuring point of the pile body;

[0017] The main reinforcement is arranged inside the reinforcement cage of the pile body, and each main reinforcement corresponds to a top displacement measuring point of the pile body reinforcement area or a bottom displacement measuring point of the pile body reinforcement area;

[0018] Tie the protective tube with displacement rod / wire to the main reinforcement;

[0019] Connect the bottom end of the upper displacement rod / wire to the top displacement measuring point of the pile body reinforcement area, connect the bottom end of the lower displacement rod / wire to the bottom displacement measuring point of the pile body reinforcement area, connect the bottom end of the top displacement rod / wire to the top displacement measuring point of the pile body, and connect the top of each displacement rod / wire to a displacement meter for displacement testing.

[0020] The beneficial effects achieved by the present invention are as follows: the present invention connects the bottom end of the upper displacement rod / wire to the top displacement measuring point of the pile body reinforcement area to test the displacement of the upper pile body, connects the bottom end of the lower displacement rod / wire to the bottom displacement measuring point of the pile body reinforcement area to test the displacement of the upper pile body, and connects the bottom end of the top displacement rod / wire to the top displacement measuring point of the pile body to test the displacement of the pile top. Compared with the existing device, the position of the displacement measuring point is adjusted so that the displacement measurement is not affected by the output of the load box jack, thereby ensuring the accuracy of the displacement result. At the same time, the adjusted displacement measuring point avoids the local stress concentration area of ​​the self-balancing test, so that the displacement test result error of two displacement points at the same elevation and in the same direction does not exceed 30% of the mean, which meets the requirements of the technical specifications for building foundation pile detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the pile reinforcement area for the static load pile test method;

[0022] Figure 2 This is a schematic diagram of the reinforcement area of ​​the self-balancing test pile;

[0023] Figure 3 It is a schematic diagram of the present invention;

[0024] Figure 4 Enlarge the image for lashing;

[0025] Figure 5 is a transverse cross-sectional view;

[0026] Figure 6 It is a schematic diagram of the testing principle of a single displacement wire;

[0027] Figure 7 Schematic diagram of the test principle of a single displacement rod. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0029] Static load pile test method, when doing pile foundation bearing capacity test, first of all, it is necessary to consider reinforcing the top 1 to 2 meters of the pile foundation, which can be achieved by densifying the main reinforcement and stirrups or burying steel casing, such as Figure 1 As shown in the figure, the reinforced area of ​​the self-balancing test pile body is composed of a load box and upper and lower trumpet bars (at an angle of 60 degrees to the horizontal plane), "L"-shaped reinforcement bars, annular reinforcement hoops, and stirrup reinforcement (for existing structures, no specific description is given), as shown in the figure. Figure 2 shown.

[0030] The static load pile test method is to evenly arrange the jacks around the center of the pile foundation section, with no gaps in the middle, to ensure that the point of action of the combined force of several jacks is always at the center of the pile foundation section, and the direction is always vertical. When the static load pile test method is conducted, steel plates need to be installed on the top and bottom surfaces of the jacks, which makes the load on the pile foundation a surface load rather than a point load, which can ensure that the entire pile foundation is evenly stressed. Figure 1 As shown. Figure 2 The self-balancing test requires that a number of jacks have reserved spaces inside, and that there are no steel plates installed on the top and bottom surfaces of the load box, so that the conduit can pass smoothly and the concrete pouring of the pile body 4 can be completed conveniently. Due to the characteristics of the self-balancing test itself, the self-balancing test cannot convert point loads into surface loads, which will inevitably cause local stress concentration on the pile body.

[0031] Generally, the lifting range of the jack is about 10cm, and according to relevant regulations, the maximum sum of the upper and lower displacement values ​​is 8cm or more, so the jack used in the load box is suitable for most self-balancing test projects. In the past, the displacement measurement points of self-balancing projects were very close to the jack, resulting in a large deviation (more than 30%) or huge deviation (nearly 2 or 3 times) of the two displacement data arranged in the same direction and at the same elevation. The test value will be seriously distorted. The reasons for this situation are complex and multifaceted, but in summary, the following reasons may be two of the many reasons:

[0032] 1. Due to the characteristics of the self-balancing test, the load cannot be converted from a point load to a surface load. When the test is loaded, as the test load increases, the difference in the output of several jacks becomes more obvious. The stress on the projection surface of the jacks with larger output will be higher than that in other areas. If the displacement measurement point is arranged near a jack, the displacement test accuracy will be greatly affected due to the relationship between the jack reaction force and the concrete of the pile body 4, resulting in distortion of the displacement test data. However, this influence is limited to the reinforcement area 3 of the pile body 4.

[0033] 2. The load box position itself is a weak area of ​​the concrete of the pile body 4. The concrete at each position has different workability, strength and other indicators from the concrete outside the reinforced area 3 of the pile body 4. Therefore, if the concrete near the displacement measuring point is relatively loose, it will inevitably lead to the expansion and distortion of the displacement test value. Similarly, there is a relationship of action and reaction between the reaction force of the jack and the concrete of the pile body 4, but this influence is only limited to the reinforced area 3 of the pile body 4.

[0034] Therefore, the displacement measuring point of the self-balancing test needs to avoid the stress concentration area of ​​the pile body 4 and then be led to the ground using a suitable device.

[0035] Based on the above analysis Figure 3 As shown, a displacement test device suitable for a self-balancing test comprises an upper displacement rod / wire pair, a lower displacement rod / wire pair and a top displacement rod / wire pair.

[0036] The upper displacement rod / wire pair includes two upper displacement rods / wires 6 arranged vertically and opposite to each other, the bottom end of the upper displacement rod / wire 6 is connected to the top displacement measuring point of the reinforcement area 3 of the pile body 4 (i.e., the top displacement measuring point of the upper horn bar), so as to test the displacement of the upper pile body 1, and the upper displacement rod / wire pair and the central axis of the pile body 4 are on the same plane;

[0037] The lower displacement rod / wire pair comprises two lower displacement rods / wires 7 arranged opposite to each other vertically, the bottom ends of the lower displacement rods / wires 7 are connected to the bottom displacement measuring point of the reinforcement area 3 of the pile body 4 (i.e., the bottom displacement measuring point of the lower horn bar), so as to test the displacement of the lower pile body 2, and the central axis of the lower displacement rod / wire pair and the pile body 4 are in the same plane;

[0038] The top displacement rod / wire pair includes two vertically arranged opposite top displacement rods / wires 5, the bottom ends of which are connected to the top displacement measuring points of the pile body 4 to test the pile top displacement, and the top displacement rod / wire pair and the central axis of the pile body 4 are in the same plane.

[0039] The part of the displacement rod / wire in the pile body 4 is passed through the protection tube 8, which is a PPR tube or a steel casing. In order to facilitate the binding of the protection tube 8, Figure 4 and 5 As shown, a plurality of vertical binding main bars 9 are arranged inside the reinforcement cage of the pile body 4, and each protection tube 8 is tied to a binding main bar 9, arranged clockwise or counterclockwise, and the length of the binding main bar 9 is equal to the length of the binding protection tube 8 located inside the pile body 4. From the plane, from the inside to the outside, they are: binding main bars 9, annular reinforcement bars 10, main bars 11, and stirrups 12, wherein the annular reinforcement bars 10, main bars 11, and stirrups 12 are components of the reinforcement cage of the pile body 4. Generally, a pair of upper displacement rods / wires and lower displacement rods / wires are provided, and the plane where the upper displacement rods / wires are located is perpendicular to the plane where the lower displacement rods / wires are located.

[0040] In the self-balancing test, both displacement rod and displacement wire are very applicable. By comparing the test principles of displacement wire and displacement rod, it can be concluded that the test effect of displacement rod is better than that of displacement wire, but the slight difference does not affect the displacement test effect of self-balancing.

[0041] The testing principle of a single displacement wire is as follows: Figure 6 As shown, the displacement wire and the protective tube 8 (PPR tube, diameter: 2cm) can be reasonably divided into lengths according to the sections of the steel cage to facilitate installation and lifting. The displacement wire is ensured to be vertical by a fixed pulley 13 and a 10Kg counterweight 14. Figure 7 As shown, the displacement rod (diameter: 1cm, hollow, rigid material, generally manufactured in factories in sections of 3m, and every 2 sections are connected by threads) and the protection tube 8 (steel casing, diameter: 2cm, generally manufactured in factories in sections of 6m, and every 2 sections are connected by welding) can also be reasonably divided into lengths according to the sections of the steel cage. The displacement rod does not need a counterweight, and only a steel sheet 16 needs to be welded at the end of the displacement rod. The displacement rod relies on the weight of the material to ensure verticality. The displacement meter 15 is fixed using a magnetic base, and only the pointer head can be freely extended and retracted, and it hardly bears any load.

[0042] The testing method of the above device comprises the following steps:

[0043] 1) Determine the top displacement measuring point of the pile body 4 reinforcement area 3, the bottom displacement measuring point of the pile body 4 reinforcement area 3, and the top displacement measuring point of the pile body 4. In general, if Figure 5 As shown, there are only two displacement test points for each type, namely, two opposite to each other.

[0044] 2) The main reinforcement 9 is arranged on the inner side of the reinforcement cage of the pile body 4, and each main reinforcement 9 corresponds to a top displacement measuring point of the reinforcement area 3 of the pile body 4 or a bottom displacement measuring point of the reinforcement area 3 of the pile body 4, that is, the bottom end of the main reinforcement 9 extends to the corresponding displacement measuring point.

[0045] 3) Tie the protective tube 8 with displacement rod / wire to the main reinforcement 9.

[0046] 4) Connect the bottom end of the upper displacement rod / wire 6 to the top displacement measuring point of the pile body 4 reinforcement area 3, connect the bottom end of the lower displacement rod / wire 7 to the bottom displacement measuring point of the pile body 4 reinforcement area 3, connect the bottom end of the top displacement rod / wire 5 to the top displacement measuring point of the pile body 4, and connect the top end of each displacement rod / wire to a displacement meter 15 for displacement testing (the connection method of the displacement meter is as follows Figure 6 and 7 As shown, it is the prior art and will not be described in detail here).

[0047] The above-mentioned device connects the bottom end of the upper displacement rod / wire 6 to the top displacement measuring point of the pile body 4 reinforcement area 3 to test the displacement of the upper pile body 1, connects the bottom end of the lower displacement rod / wire 7 to the bottom displacement measuring point of the pile body 4 reinforcement area 3 to test the displacement of the lower pile body 2, and connects the bottom end of the top displacement rod / wire 5 to the top displacement measuring point of the pile body 4 to test the pile top displacement. Compared with the existing device, the position of the displacement measuring point is adjusted so that the displacement measurement is not affected by the output of the load box jack, thereby ensuring the accuracy of the displacement result; at the same time, the adjusted displacement measuring point avoids the local stress concentration area of ​​the self-balancing test. Even if the concrete near each displacement measuring point and the accuracy of each displacement meter have individual differences, the displacement test result error of two displacement points at the same elevation and in the same direction does not exceed 30% of the mean, which meets the requirements of the technical specifications for building foundation pile detection.

[0048] The displacement rod / wire of the above-mentioned device is located in the protective tube 8, and the protective tube 8 is tied to the main binding reinforcement 9 located on the inner side of the steel cage. With the protection of the steel cage, the damage to the displacement test system caused by interference from external factors can be minimized, and the vertical main binding reinforcement 9 can ensure the verticality of the protective tube 8 to the greatest extent, thereby ensuring the verticality of the displacement rod / wire, and further ensuring the accuracy of the displacement result.

[0049] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A displacement test device suitable for self-balancing test, characterized in that: It includes an upper displacement rod / wire pair, a lower displacement rod / wire pair, and a top displacement rod / wire pair; The upper displacement rod / wire pair includes two upper displacement rods / wires arranged vertically and opposite to each other. The bottom ends of the upper displacement rods / wires are connected to the top displacement measuring points of the horn bars in the pile body reinforcement area to test the displacement of the upper pile body. The upper displacement rod / wire pair and the central axis of the pile body are in the same plane. The lower displacement rod / wire pair includes two lower displacement rods / wires arranged vertically and opposite to each other. The bottom ends of the lower displacement rods / wires are connected to the bottom displacement measuring points of the lower horn bars in the pile body reinforcement area to test the displacement of the lower pile body. The lower displacement rod / wire pair and the central axis of the pile body are on the same plane. The top displacement rod / wire pair includes two vertically arranged opposite top displacement rods / wires, the bottom ends of which are connected to the top displacement measuring points of the pile body to test the pile top displacement, and the top displacement rod / wire pair and the central axis of the pile body are in the same plane.

2. A displacement testing device suitable for self-balancing test according to claim 1, characterized in that: The part of the displacement rod / wire inside the pile body is passed through the protective tube.

3. A displacement testing device suitable for self-balancing test according to claim 2, characterized in that: The protective tube is a PPR tube or a steel casing.

4. A displacement test device suitable for self-balancing test according to claim 2, characterized in that: A number of vertical main reinforcement bars are arranged on the inner side of the pile body reinforcement cage, and each protective tube is tied to a main reinforcement bar.

5. A displacement testing device suitable for self-balancing test according to claim 4, characterized in that: The length of the tied main reinforcement is equal to the length of the tied protective tube inside the pile body.

6. A displacement testing device suitable for self-balancing test according to claim 1, characterized in that: There is one pair of upper displacement rod / wire pair and one pair of lower displacement rod / wire pair, and the plane where the upper displacement rod / wire pair is located is perpendicular to the plane where the lower displacement rod / wire pair is located.

7. A testing method for a displacement testing device suitable for a self-balancing test based on any one of claims 4 or 5, characterized in that: include, Determine the displacement measuring point of the top end of the trumpet reinforcement in the pile body reinforcement area, the bottom end of the trumpet reinforcement in the pile body reinforcement area, and the top end of the pile body; The main binding reinforcement is arranged on the inner side of the pile body reinforcement cage, and each main binding reinforcement corresponds to a top displacement measuring point of the trumpet reinforcement in the upper reinforcement area of ​​the pile body or a bottom displacement measuring point of the trumpet reinforcement in the lower reinforcement area of ​​the pile body; Tie the protective tube with displacement rod / wire to the main reinforcement; Connect the bottom end of the upper displacement rod / wire to the top displacement measuring point of the upper horn reinforcement in the pile body reinforcement area, connect the bottom end of the lower displacement rod / wire to the bottom displacement measuring point of the lower horn reinforcement in the pile body reinforcement area, connect the bottom end of the top displacement rod / wire to the top displacement measuring point of the pile body, and connect the top of each displacement rod / wire to a displacement meter for displacement testing.

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