Device and method for testing jacking force of concrete jacking pipe

Abstract

The invention belongs to the technical field of concrete testing, and particularly relates to a concrete jacking pipe jacking force testing device and method.The device comprises a counter-force support, a load mechanism and a deformation testing system.The load mechanism is arranged at the top of the counter-force support and used for applying load to a concrete jacking pipe below the load mechanism; the deformation testing system comprises a first pressure sensor and a linear displacement sensor, the first pressure sensor is arranged on the load mechanism and used for detecting the load applied to the top end face of the concrete jacking pipe by the load mechanism, and the linear displacement sensor is vertically arranged in the middle of the side wall of the concrete jacking pipe and used for detecting the compressive strain of the concrete jacking pipe. According to the method, on one hand, the local damage load of the top section of the jacking pipe is tested, the maximum jacking force of the jacking pipe can be accurately calculated based on load data at the local damage load, and therefore the reliability of test data is improved, and on the other hand, due to the fact that jacking pipe compression strain detection is added, effective judgment on local damage failure of the top section of the jacking pipe is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete testing, and in particular relates to a concrete jacking pipe jacking force testing device and a testing method. Background Art

[0002] In recent years, with the in-depth development of urban cable engineering construction, cable tunnels in large urban power grids have become the main laying method for high-voltage and large-section cables. The construction methods of cable tunnels mainly include open-cut method, pipe jacking method, and shield method. Compared with the open-cut method, pipe jacking construction can solve the problems of pipeline relocation, land acquisition and demolition, traffic relief, and environmental impact in the central urban area. Compared with the shield method, pipe jacking construction has a small scale, a variety of sizes, low cost, and simple process. Therefore, pipe jacking technology has become a widely used design and construction scheme for cable tunnels. Before pipe jacking construction, it is necessary to calculate the pipe jacking force. The pipe jacking force is the basic data for determining the length of the pipe jacking unit. It plays a key role in the overall stability and structural safety design and construction of the back wall of the working shaft. It is also the basis for determining the number of working shafts, structural forms, pipe jacking construction plans, and engineering period and cost. The jacking force of the jacking construction is set according to the maximum jacking force value allowed by the jacking pipe to prevent the jacking pipe from breaking due to the jacking force exceeding the maximum allowable jacking force of the pipeline during the jacking process. Therefore, the maximum jacking force test of the pipe jacking before construction is very important in the jacking construction.

[0003] At present, there is a lack of concrete jacking force testing equipment and testing methods at construction sites. Theoretical calculations are usually used, but the theoretical calculation values ​​are relatively conservative and cannot truly reflect the allowable jacking force and deformation of the actual pipeline. It is difficult to truly evaluate the maximum jacking force and maximum deformation allowed for large-diameter concrete jacking pipes, especially the jacking pipe damage caused by large deformation during jacking construction. There is no corresponding evaluation basis. In view of this, it is necessary to develop a large-diameter concrete jacking force test device and test method to solve the problem that the maximum jacking force of concrete jacking pipes is difficult to quantify. Summary of the invention

[0004] The purpose of the present invention is to provide a concrete jacking force test device and a test method for measuring the jacking force of a jacking pipe, which can accurately measure the maximum allowable jacking force of the jacking pipe.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] In a first aspect, the present invention provides a concrete jacking force test device, the test device comprising a reaction support, a load mechanism, and a deformation test system. The load mechanism is arranged on the top of the reaction support and is used to apply a load to the concrete jacking pipe below. The deformation test system comprises a No. 1 pressure sensor and a linear displacement sensor. The No. 1 pressure sensor is arranged on the load mechanism and is used to detect the load amount applied by the load mechanism to the top end face of the concrete jacking pipe. The linear displacement sensor is vertically arranged in the middle of the side wall of the concrete jacking pipe and is used to detect the compressive strain of the concrete jacking pipe.

[0007] The load mechanism includes a hydraulic jack, a distribution beam, and a loading block. The distribution beam is a cross-shaped structure, consisting of two crossed steel plates. The intersection of the two steel plates is connected to the top of the reaction support through a hydraulic jack, and the end of the steel plate is connected to the loading block through a No. 1 pressure sensor. The loading block is used to contact the top end face of the concrete jacking pipe.

[0008] The linear displacement sensor is correspondingly arranged directly below the No. 1 pressure sensor.

[0009] The deformation testing system also includes a No. 2 pressure sensor, which is arranged between the hydraulic jack and the top of the reaction support.

[0010] The reaction force support comprises a base, a crossbeam and two columns. The two columns are arranged on the base. The two ends of the crossbeam are respectively connected to the two columns, and the middle part of the crossbeam is connected to the load mechanism.

[0011] A plurality of first bolt holes are provided on the column along its height direction, and second bolt holes are provided on both ends of the crossbeam, and the second bolt holes are fixed to the first bolt holes by bolts.

[0012] The base comprises a bottom plate, and the two columns are both arranged on the bottom plate. The bottom plate is provided with a plurality of radially distributed slideways, and the slideways are provided with steel pads that can move along the slideways, and the steel pads are used to place concrete jacking pipes.

[0013] The slide includes two baffles installed on the bottom plate, the steel pad is located between the two baffles and can move along the length direction of the baffle, the baffle is provided with a limit assembly, the limit assembly includes a mounting seat, a No. 1 limit bolt, and a No. 2 limit bolt, the mounting seat is sleeved on the top of the baffle, the mounting seat and the baffle are fixed by a No. 1 limit bolt, and the mounting seat and the pad are fixed by a No. 2 limit bolt.

[0014] In a second aspect, the present invention provides a concrete pipe jacking force test method, the test method comprising:

[0015] S1, control the load mechanism to uniformly load to a preset first top force load, wherein the preset first top force load is less than the theoretical maximum allowable top force load; record the crack width and compressive strain, and if the crack width reaches or exceeds the maximum allowable crack width, the load at this time is used as the ultimate load of the concrete jacking pipe; if the crack width is less than the maximum allowable crack width or there is no crack, enter S2;

[0016] S2. Control the load mechanism to load in stages to the maximum theoretically allowable top load; record the crack width and compressive strain. If the crack width is still less than the maximum allowable crack width or the compressive strain is less than 80% of the ultimate compressive strain of concrete of the corresponding grade, continue to load in stages until the crack width reaches the maximum allowable crack width or the compressive strain reaches 80% of the ultimate compressive strain of concrete of the corresponding grade. The load at this time is taken as the ultimate load of the concrete top pipe;

[0017] S3. Calculate the local concrete strength and maximum jacking force of the concrete jacking pipe based on the ultimate load.

[0018] The local concrete strength of the concrete jacking pipe is calculated according to the following formula:

[0019]

[0020] In the above formula, σ represents the local concrete strength of the concrete jacking pipe; F1 represents the ultimate load of the concrete jacking pipe; A1 represents the contact area where the load mechanism applies load to the top end face of the concrete jacking pipe;

[0021] The maximum jacking force of the concrete pipe is calculated according to the following formula:

[0022]

[0023] In the above formula, F represents the maximum jacking force of the concrete jacking pipe; It indicates the reduction factor of compressive strength of concrete material; It represents the coefficient of improvement in eccentric compressive strength; Indicates the material brittleness coefficient; represents the standard adjustment coefficient of concrete strength; γ represents the jacking force partial coefficient; A represents the top end surface area of ​​the concrete jacking pipe.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. A concrete jacking force test device of the present invention comprises a reaction support, a load mechanism, and a deformation test system. The load mechanism is arranged on the top of the reaction support and is used to apply a load to the concrete jacking pipe below. The deformation test system comprises a No. 1 pressure sensor and a linear displacement sensor. The No. 1 pressure sensor is arranged on the load mechanism and is used to detect the load applied by the load mechanism to the top end face of the concrete jacking pipe. The linear displacement sensor is vertically arranged in the middle of the side wall of the concrete jacking pipe and is used to detect the compressive strain of the concrete jacking pipe. During the test, on the one hand, the load of local damage of the top section of the jacking pipe is tested, and the maximum jacking force of the jacking pipe can be accurately calculated based on the load data at this place, thereby improving the reliability of the test method data. On the other hand, the load when the crack width reaches the maximum allowable crack width or the compressive strain reaches 80% of the ultimate compressive strain of the corresponding grade of concrete is used as the ultimate load of the concrete jacking pipe. Due to the increase of the jacking pipe compressive strain detection, the effective judgment of the local damage failure of the top section of the jacking pipe is improved. Therefore, the present invention can accurately measure the maximum allowable jacking force of the jacking pipe, compare the actual measured maximum allowable jacking force of the jacking pipe with the theoretical maximum allowable jacking force value, and provide guidance for the actual construction process.

[0026] 2. The concrete jacking force test device of the present invention sets the linear displacement meter just below the No. 1 pressure sensor and in the middle section of the jacking pipe, which can reduce the influence of the extrusion of the upper and lower ends of the jacking pipe on the compressive strain test data. Therefore, the present invention can improve the reliability of the compressive strain test data.

[0027] 3. The load mechanism in the concrete jacking force test device of the present invention includes a hydraulic jack, a distribution beam, and a loading block. The distribution beam is a cross-shaped structure, which can load the top section of the jacking pipe at four points evenly, prevent uneven force at each loading point, and improve the accuracy of the pressure test data. Therefore, the present invention can improve the accuracy of the pressure test data.

[0028] 4. The reaction force support in a concrete jacking force test device of the present invention comprises a base, a crossbeam, and two columns. The two columns are both arranged on the base. A plurality of first bolt holes are opened on the columns along their height direction. Second bolt holes are opened on both ends of the crossbeam. The second bolt holes are fixed to the first bolt holes by bolts. By selecting a suitable height to install the crossbeam, it can adapt to the test of jacking pipes of different heights, thereby improving the versatility and flexibility of the test device.

[0029] 5. The base of a concrete jacking pipe force testing device of the present invention is provided with a slideway and a steel pad that can move along the slideway; the steel pad is moved to a suitable position to adapt to the testing of jacking pipes with different inner diameters, thereby further improving the versatility and flexibility of the testing device. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1It is a schematic diagram of the structure of the device of the present invention.

[0031] Figure 2 It is a structural schematic diagram of the concrete jacking pipe in the present invention.

[0032] Figure 3 It is a structural schematic diagram of the loading block in the present invention.

[0033] Figure 4 It is the front view of the reaction support in the present invention.

[0034] Figure 5 It is a side view of the reaction support in the present invention.

[0035] Figure 6 It is a structural schematic diagram of the crossbeam in the present invention.

[0036] Figure 7 It is a structural schematic diagram of the distribution beam in the present invention.

[0037] Figure 8 It is a structural schematic diagram of the base in the present invention.

[0038] Fig. 9 It is a schematic diagram of the structure of the limiting component in the present invention.

[0039] Fig.10 The present invention is a flowchart of the method.

[0040] In the above figure, reaction support 1, base 11, bottom plate 111, slide 112, steel pad 113, baffle 114, mounting seat 115, No. 1 limit bolt 116, No. 2 limit bolt 117, cross beam 12, second bolt hole 121, column 13, first bolt hole 131, load mechanism 2, hydraulic jack 21, distribution beam 22, steel plate 221, loading block 23, deformation test system 3, No. 1 pressure sensor 31, linear displacement sensor 32, No. 2 pressure sensor 33, concrete jacking pipe 4. DETAILED DESCRIPTION

[0041] The present invention is further described in detail below in conjunction with specific implementations and drawings.

[0042] Figure 1The invention provides a preferred embodiment of a concrete jacking force test device, comprising a reaction support 1, a load mechanism 2, and a deformation test system 3. The load mechanism 2 is arranged on the top of the reaction support 1, and is used to apply a load to the concrete jacking pipe 4 below. The deformation test system 3 comprises a No. 1 pressure sensor 31 and a linear displacement sensor 32. The No. 1 pressure sensor 31 is arranged on the load mechanism 2, and is used to detect the load amount applied by the load mechanism 2 to the top end face of the concrete jacking pipe 4. The linear displacement sensor 32 is vertically arranged in the middle of the side wall of the concrete jacking pipe 4, and is used to detect the compressive strain of the concrete jacking pipe 4. When the above test device is used for testing, the crack width and the compressive strain are recorded, and the load when the crack width reaches the maximum allowable crack width or the compressive strain reaches 80% of the ultimate compressive strain of the corresponding grade of concrete is used as the ultimate load of the concrete jacking pipe 4. The maximum allowable jacking force of the jacking pipe is calculated based on the ultimate load, which solves the problem that the maximum allowable jacking force of the concrete jacking pipe is not easy to quantify and evaluate. The calculated maximum allowable jacking force of the jacking pipe is compared with the theoretical maximum allowable jacking force value, and guidance is provided for the actual construction process.

[0043] In another embodiment of the present invention, the load mechanism 2 includes a hydraulic jack 21, a distribution beam 22, and a loading block 23. The distribution beam 22 is a cross-shaped structure, composed of two crossed steel plates 221. The intersection of the two steel plates 221 is connected to the top of the reaction support 1 through the hydraulic jack 21, and the end of the steel plate 221 is connected to the loading block 23 through a No. 1 pressure sensor 31. The loading block 23 is used to contact the top end face of the concrete jacking pipe 4.

[0044] Specifically, the measuring range of the hydraulic jack 21 is 200-500T, the measuring range of the No. 1 pressure sensor 31 is 60-100T, and the sensitivity is 2mV / V; the linear displacement sensor 32 is pasted on the middle section of the concrete jacking pipe 4 with epoxy resin, and the linear displacement sensor 32 and the No. 1 pressure sensor 31 are connected to the Donghua static strain test system through a signal line. The Donghua static strain test system automatically collects data and saves it in a laptop computer, and the test data can be viewed in real time through the laptop computer.

[0045] Specifically, Figure 7As shown, the steel plate 221 is a low-alloy high-strength structural steel plate with a length of 2.5m, a width of 300-400mm, a thickness of 20-30mm, a flatness error of less than 2mm, and a yield strength of not less than 355MPa; the two steel plates 221 are welded into a cross-shaped structure, which can improve the rigidity of the distribution beam and withstand a load of 200-500T without plastic deformation; the distribution beam 22 is provided with a lifting lug and a distribution beam rib plate, and the distribution beam rib plate is a low-alloy high-strength structural steel plate with a thickness of 12-20mm, a height of 50-150mm, a width of 80-120mm, a spacing of 250-350mm, and a yield strength of not less than 355MPa; the lifting lug is welded by HPB235 hot-rolled round steel bars with a diameter of 8-12mm, and the aperture of the lifting lug is 20-25mm, which is used to adjust the height of the distribution beam 22;

[0046] Specifically, Figure 2 , Figure 3 As shown, the loading block 23 is a 16MnR low-alloy high-strength square steel block with a width of 100mm, and a 3mm arc chamfer is set around it to prevent stress concentration; there are four loading blocks 23, corresponding to the four loading points arranged on the center line of the top section of the concrete jacking pipe 4; when the load deviation value of each loading point is greater than 20%, it means that the loading point is unevenly stressed, and the loading position should be adjusted and reloaded to improve the accuracy of the test data; the length of the loading block 23 is not less than the wall thickness of the concrete jacking pipe 4 to ensure that the loading block 23 completely covers the wall thickness of the concrete jacking pipe 4; in order to adapt to jacking pipes with different wall thicknesses, four different lengths of concrete jacking pipes 4 are set: the length of the loading block 23 suitable for wall thicknesses of 1000-1500mm is 150mm, the length of the loading block 23 suitable for wall thicknesses of 1600-2000mm is 200mm, the length of the loading block 23 suitable for wall thicknesses of 2200-3000mm is 300mm, and the length of the loading block 23 suitable for wall thicknesses of 3200-4000mm is 350mm;

[0047] In another embodiment of the present invention, the linear displacement sensor 32 is correspondingly disposed directly below the first pressure sensor 31 .

[0048] In another embodiment of the present invention, the deformation testing system 3 further includes a No. 2 pressure sensor 33, which is located between the hydraulic jack 21 and the top of the reaction support 1. Specifically, the No. 2 pressure sensor 33 has a range of 200-500T and a sensitivity of 2mV / V, and the No. 2 pressure sensor 33 is connected to the Donghua static strain testing system through a signal line.

[0049] Specifically, both ends of the No. 2 pressure sensor 33 are provided with No. 1 steel pads, and both ends of the No. 1 pressure sensor 31 are provided with No. 2 steel pads. The No. 1 steel pad is a low-alloy high-strength structural steel plate with a thickness of 20-30mm, a length of 350-450mm, a width of 350-500mm, a flatness of less than 1mm, and a yield strength of not less than 355MPa. The No. 1 steel pad is a low-alloy high-strength structural steel plate with a thickness of 20-24mm, a length of 250-450mm, a width of 250-450mm, a flatness error of less than 1mm, and a yield strength of not less than 355MPa. The provision of steel pads can reduce the change in the stress state of the pressure sensor caused by the inclination of the contact surface, thereby improving the measurement accuracy of the pressure sensor.

[0050] like Figure 4 As shown, in another embodiment of the present invention, the reaction support 1 includes a base 11, a beam 12, and two columns 13. The two columns 13 are both arranged on the base 11, the two ends of the beam 12 are respectively connected to the two columns 13, and the middle part of the beam 12 is connected to the load mechanism 2.

[0051] Specifically, Figure 5 As shown, the column 13 is 4-6m high and is welded by two 32c-40c channel steels through a column connection key. The column connection key is a low-alloy high-strength structural steel plate with a thickness of 12-6mm, a width of 120-160mm, and a yield strength of not less than 355MPa. The bottom of the column 13 is anchored to the reaction base by bolts. A stiffening plate is provided at a distance of 100-150mm from the bottom of the column 13. The stiffening plate is a right-angled triangle structure and is a low-alloy high-strength structural steel plate with a thickness of 16-20mm, a height of 100-150mm, and a yield strength of not less than 355MPa. A diagonal brace is also provided on the column 13. The diagonal brace is made of 18c-22c channel steel. The top of the diagonal brace is connected to the column 13 by bolts, and the bottom of the diagonal brace is anchored to the base 11 by bolts, which can improve the stability of the reaction support 1.

[0052] Specifically, Figure 6 As shown, the cross beam 12 is a 32c-40c channel steel, which can withstand a load of 200-500T without plastic deformation; the cross beam 12 is provided with three cross beam ribs and lifting ears, and the cross beam ribs are low-alloy high-strength structural steel plates with a thickness of 12-20mm, a spacing of 200-300mm, and a yield strength of not less than 355MPa; the lifting ears are formed by welding HPB235 hot-rolled round steel bars with a diameter of 8-12mm on the cross beam channel steel, and the hole diameter of the lifting ears is 20-25mm, which is used to connect with the lifting device to adjust the height of the cross beam 12;

[0053] In another embodiment of the present invention, a plurality of first bolt holes 131 are provided at the upper portion of the column 13 along its height direction, and the diameter of the first bolt holes 131 is 56-66 mm. Second bolt holes 121 are provided at both ends of the beam 12, and the diameter of the second bolt holes 121 is 56-66 mm. After adjusting the height of the beam 12, the two ends of the beam 12 are respectively inserted into the connecting keys of the two columns 13, and the second bolt holes 121 and the first bolt holes 131 are fixed with bolts with a diameter of 50-60 mm.

[0054] like Figure 8 As shown, in another embodiment of the present invention, the base 11 includes a bottom plate 111, and the two columns 13 are anchored to the bottom plate 111 by bolts. The bottom plate 111 is provided with eight slideways 112 distributed in a cross shape, and the slideways 112 are provided with steel pads 113 that can move along the slideways 112, and the steel pads 113 are used to place the concrete jacking pipe 4.

[0055] Specifically, the bottom plate 111 is a low-alloy high-strength structural steel plate with a thickness of 12-16 mm, a flatness error of less than 5 mm, a length of 5 m, a width of 5 m, and a yield strength of not less than 355 MPa. The eight slideways 112 are distributed in a cross shape with the center position of the bottom plate 111 as the origin. The height of the slideway 112 is less than 50 mm. The height of the steel pad 113 above the slideway 112 is greater than the reserved length of the socket steel ring, ensuring that the steel pad 113 can contact the bottom end section of the concrete jacking pipe 4.

[0056] Specifically, the steel pad 113 is moved along the slide 112 to adapt to the concrete jacking pipes 4 of different diameters; a scale is provided along the slide 112 to accurately adjust the position of the steel pad 113. In order to adapt to the concrete jacking pipes 4 of different diameters and wall thicknesses, four steel pads 113 of different lengths are provided: 150mm steel pad 113 is suitable for 1000-1500mm diameter wall thickness, 200mm steel pad 113 is suitable for 1600-2000mm diameter wall thickness, 300mm steel pad 113 is suitable for 2200-3000mm diameter wall thickness, and 350mm steel pad 113 is suitable for 3200-400mm diameter wall thickness. When it is necessary to test the concrete jacking pipes 4 of different diameters and wall thicknesses, the steel pad 113 of the appropriate size is selected and moved to the appropriate position.

[0057] In another embodiment of the present invention, Fig. 9As shown, the slide 112 includes two baffles 114 installed on the base plate 111, the steel pad 113 is located between the two baffles 114 and moves along the length direction of the baffle 114, and a limiting assembly is provided on the baffle 114, the limiting assembly includes a mounting seat 115, a No. 1 limiting bolt 116, and a No. 2 limiting bolt 117, and the mounting seat 115 is sleeved on the top of the baffle 114; after adjusting the position of the steel pad 113, the No. 1 limiting bolt 116 is passed through the bottom of the mounting seat 115 to abut against the baffle 114, so that the mounting seat 115 and the baffle 114 are fixed, and the No. 2 limiting bolt 117 is passed through the top of the mounting seat 115 to abut against the steel pad 113, so that the top of the mounting seat 115 and the steel pad 113 are fixed.

[0058] See also Fig.10 The present invention also proposes a concrete pipe jacking force test method, which is based on the above concrete pipe jacking force test device and has the following steps:

[0059] S1. Preparation before the test: Before the test, ensure that the concrete jacking pipe 4 is dry and dust-free. The loading block 23 should not be placed above the longitudinal reinforcement of the concrete jacking pipe 4. When installing the load device, the hydraulic jack 21 should be placed stably and kept vertical with the distribution beam 22 and the second pressure sensor 33 to avoid the hydraulic jack 21 tipping over during pressurization and affecting the accuracy of the test. The first pressure sensor 31 and the second pressure sensor 33 need to be calibrated before the test. The linear displacement sensor 32 is fixed at the half pipe height position just below the loading block 23.

[0060] S2. Preloading: Observe the No. 2 pressure sensor 33, use the hydraulic jack 21 to preload to 50 kN, hold the load for 3 minutes, check whether all instruments and loading equipment can operate normally and eliminate the contact gap of each part; adjust to zero after unloading;

[0061] S3, formal test: control the load mechanism 2 to uniformly load at a constant rate of 50±10 kN / min to 50% of the theoretical maximum allowable top load, and hold the load for 1 minute. During this period, the load amount is controlled by the No. 2 pressure sensor 33;

[0062] Record the crack width and compressive strain during the uniform loading process. If the crack width reaches or exceeds the maximum allowable crack width, the load at this time is used as the limit load of the concrete jacking pipe 4. If the crack width is less than the maximum allowable crack width or there is no crack, enter S4. In this embodiment, the maximum allowable crack width is set to 0.2 mm.

[0063] S4, control the load mechanism 2 to load in stages, each stage is loaded at 10% of the theoretical maximum allowable top load, each stage is loaded for 1 minute, until it reaches 100% of the theoretical maximum allowable top load, and the load is held for 3 minutes;

[0064] Record the crack width and compressive strain during the graded loading process. If the crack width is still less than the maximum allowable crack width or the compressive strain is less than 80% of the ultimate compressive strain of the corresponding grade of concrete, continue to grade the loading, adding 5% of the theoretical maximum allowable top load at each level, and holding the load for 3 minutes at each level until the crack width reaches the maximum allowable crack width or the compressive strain reaches 80% of the ultimate compressive strain of the corresponding grade of concrete. The load at this time is taken as the ultimate load of the concrete jacking pipe 4;

[0065] It should be noted that during the loading period, if the hydraulic jack 21 can continue to load when loaded to 80% of its maximum load, the loading should be stopped for safety reasons, and a jack with a larger range should be replaced to conduct the jacking test again;

[0066] S5. Data processing: After the jacking test is completed, the local concrete strength of the concrete jacking pipe 4 is calculated according to the following formula. The local concrete strength can be used to determine the concrete strength quality:

[0067]

[0068] In the above formula, σ represents the local concrete strength of the concrete jacking pipe 4; F1 represents the ultimate load of the concrete jacking pipe 4; A1 represents the contact area of ​​the load mechanism 2 applying the load to the top end face of the concrete jacking pipe 4, and in this embodiment, it refers to the sum of the contact areas of all the loading blocks 23 and the top cross section of the concrete jacking pipe 4;

[0069] The maximum jacking force of the concrete jacking pipe 4 is calculated according to the following formula, and the calculated maximum jacking force is compared with the theoretical maximum allowable jacking force value to provide guidance for the actual construction process:

[0070]

[0071] In the above formula, F represents the maximum jacking force of the concrete jacking pipe 4; It represents the reduction factor of the compressive strength of concrete material, which is generally taken as 0.9; It represents the coefficient of strength enhancement under eccentric compression, which is generally taken as 1.05; Indicates the material brittleness coefficient, generally taken as 0.85; represents the standard adjustment coefficient of concrete strength, which is generally taken as 0.79; γ represents the top force partial coefficient, which is generally taken as 1.3; A represents the top cross-sectional area of ​​the concrete top pipe 4.

[0072] Obviously, the embodiments described above are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A concrete pipe jacking force test device, characterized in that: The test device comprises a reaction support (1), a load mechanism (2), and a deformation test system (3). The load mechanism (2) is arranged at the top of the reaction support (1) and is used to apply a load to a concrete jacking pipe (4) below. The deformation test system (3) comprises a first pressure sensor (31) and a linear displacement sensor (32). The first pressure sensor (31) is arranged on the load mechanism (2) and is used to detect the load applied by the load mechanism (2) to the top end face of the concrete jacking pipe (4). The linear displacement sensor (32) is vertically arranged in the middle of the side wall of the concrete jacking pipe (4) and is used to detect the compressive strain of the concrete jacking pipe (4).

2. A concrete jacking force testing device according to claim 1, characterized in that: The load mechanism (2) comprises a hydraulic jack (21), a distribution beam (22), and a loading block (23); the distribution beam (22) is a cross-shaped structure, and is composed of two intersecting steel plates (221); the intersection of the two steel plates (221) is connected to the top of the reaction support (1) through the hydraulic jack (21); the end of the steel plate (221) is connected to the loading block (23) through a No. 1 pressure sensor (31); and the loading block (23) is used to contact the top end surface of the concrete jacking pipe (4).

3. A concrete jacking force testing device according to claim 1, characterized in that: The linear displacement sensor (32) is correspondingly arranged directly below the No. 1 pressure sensor (31).

4. A concrete jacking force testing device according to claim 2, characterized in that: The deformation testing system (3) further comprises a second pressure sensor (33), wherein the second pressure sensor (33) is arranged between the hydraulic jack (21) and the top of the reaction support (1).

5. A concrete jacking force testing device according to claim 1, characterized in that: The reaction force support (1) comprises a base (11), a crossbeam (12), and two upright columns (13); the two upright columns (13) are both arranged on the base (11); the two ends of the crossbeam (12) are respectively connected to the two upright columns (13); and the middle part of the crossbeam (12) is connected to the load mechanism (2).

6. A concrete jacking force testing device according to claim 5, characterized in that: The upright column (13) is provided with a plurality of first bolt holes (131) along its height direction, and both ends of the crossbeam (12) are provided with second bolt holes (121), and the second bolt holes (121) are fixed to the first bolt holes (131) by bolts.

7. A concrete pipe jacking force testing device according to claim 5, characterized in that: The base (11) comprises a bottom plate (111), the two uprights (13) are both arranged on the bottom plate (111), a plurality of radially distributed slideways (112) are arranged on the bottom plate (111), the slideways (112) are provided with steel pads (113) movable along the slideways (112), and the steel pads (113) are used to place the concrete jacking pipe (4).

8. A concrete pipe jacking force testing device according to claim 7, characterized in that: The slideway (112) comprises two baffles (114) mounted on the bottom plate (111); the steel pad (113) is located between the two baffles (114) and can move along the length direction of the baffle (114); a limiting assembly is provided on the baffle (114); the limiting assembly comprises a mounting seat (115), a first limiting bolt (116), and a second limiting bolt (117); the mounting seat (115) is sleeved on the top of the baffle (114); the mounting seat (115) and the baffle (114) are fixed by the first limiting bolt (116); and the mounting seat (115) and the pad are fixed by the second limiting bolt (117).

9. A concrete pipe jacking force test method, characterized in that: The test method includes: S1, controlling the load mechanism (2) to uniformly apply load to a preset first jacking load, wherein the preset first jacking load is less than the theoretical maximum allowable jacking load; recording the crack width and compressive strain, and if the crack width reaches or exceeds the maximum allowable crack width, taking the load at this time as the limit load of the concrete jacking pipe (4); if the crack width is less than the maximum allowable crack width or there is no crack, entering S2; S2, controlling the load mechanism (2) to apply load in stages to the theoretical maximum allowable jacking load; recording the crack width and compressive strain; if the crack width is still less than the maximum allowable crack width or the compressive strain is less than 80% of the ultimate compressive strain of concrete of the corresponding grade, continuing to apply load in stages until the crack width reaches the maximum allowable crack width or the compressive strain reaches 80% of the ultimate compressive strain of concrete of the corresponding grade, and taking the load at this time as the ultimate load of the concrete jacking pipe (4); S3. Calculate the local concrete strength and the maximum jacking force of the concrete jacking pipe (4) according to the ultimate load.

10. A concrete pipe jacking force test method according to claim 9, characterized in that: The local concrete strength of the concrete jacking pipe (4) is calculated according to the following formula: In the above formula, σ represents the local concrete strength of the concrete jacking pipe (4); F1 represents the ultimate load of the concrete jacking pipe (4); A1 represents the contact area of ​​the load mechanism (2) applying the load to the top end face of the concrete jacking pipe (4); The maximum jacking force of the concrete jacking pipe (4) is calculated according to the following formula: In the above formula, F represents the maximum jacking force of the concrete jacking pipe (4); It indicates the reduction factor of compressive strength of concrete material; It represents the coefficient of improvement in eccentric compressive strength; Indicates the material brittleness coefficient; represents the standard adjustment coefficient of concrete strength; γ represents the jacking force partial coefficient; and A represents the top end surface area of ​​the concrete jacking pipe (4).

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