Method and device for testing water filling and draining of a pre-cracked reinforced concrete lined pressure tunnel

Abstract

The application discloses a kind of prefabricated crack reinforced concrete lining pressure tunnel filling and draining test device and method. Test device is by cylindrical barrel, contains prefabricated crack reinforced concrete lining, surrounding rock, geotextile, front flange, rear flange and monitoring instrument. The inner wall of the cylindrical barrel is the surrounding rock, and the inside of the surrounding rock is the reinforced concrete lining with prefabricated cracks. The front and rear flanges are fixed at both ends of the cylindrical barrel. The test device is used to conduct filling and draining test on the pressure tunnel, observe the change of the prefabricated crack width, and the operating state of the pressure tunnel. Compared with the existing test device and method, the application can accurately capture the dynamic evolution characteristics of the inner water exosmosis evolution, lining structure stress, lining crack width change and lining and surrounding rock contact state of the reinforced concrete lining pressure tunnel during filling and draining operation, reflecting the true operating working properties and mechanism of the reinforced concrete lining pressure tunnel.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of reinforced concrete (referred to as reinforced concrete) lining pressure tunnel model as the research object of filling and draining test device and test method, specifically, it relates to a kind of filling and draining test device and test method with prefabricated crack reinforced concrete lining pressure tunnel model as the research object.The present application belongs to the technical field of water permeable lining pressure tunnel engineering in water conservancy and hydropower engineering. BACKGROUND

[0002] High water head pressure tunnel is an important part of water diversion system of hydropower station and pumped storage power station, and the design of tunnel lining structure is the key and difficulty of engineering construction. In recent years, reinforced concrete lining is a commonly used lining structure type for high water head pressure tunnel. However, under the action of high water head, the concrete lining of pressure tunnel will crack and permeate water, and under the action of high seepage water flow, the lining and surrounding rock of pressure tunnel will separate, which will cause significant changes in the operation mechanism and hydraulic conduction behavior of pressure tunnel, and cause certain hidden dangers to the safety of pressure tunnel during use.

[0003] In particular, at present, how does the width of the lining crack change during the filling and draining process of the pressure tunnel after the cracking of the concrete lining of the pressure tunnel? How do the lining and surrounding rock work together? And how do they share the water load? The engineering designers in the industry do not understand.

[0004] Looking at the current research status, there are few physical model test studies on concrete lining pressure tunnel at present, and it is still in the exploratory stage. Moreover, the existing model test devices cannot effectively monitor the change process of the lining crack width. Influenced by construction quality, temperature effect and the degree of lining and surrounding rock adhesion, the cracking position of the concrete lining of pressure tunnel under high water head shows great randomness. The cracking position of the lining cannot be predicted in advance before the test, so the current test device cannot accurately and effectively monitor the change of the lining crack width by arranging joint meters in advance. Even if a number of continuous optical fiber sensors are arranged in the lining, they are often damaged during the lining pouring process and cannot effectively monitor the change of the crack width, so the existing model test device cannot capture the change rule of the lining crack width of pressure tunnel during the filling and draining process.

[0005] The stress evolution of the concrete lining and the steel bar and the cracking position of the lining are closely related during the filling and draining process of the tunnel. As mentioned above, the cracking position of the lining cannot be predicted before the test, so the monitoring instruments such as strain gauges and steel bars arranged in advance have great contingency during the test, which makes it difficult to monitor the stress change at the cracking position and other uncracked positions of the lining, and thus the existing model test device cannot accurately reveal the real running working characteristics of the reinforced concrete lining pressure tunnel during the filling and draining process. In addition, most of the existing physical model tests are water filling tests, which mainly focus on the cracking characteristics of the reinforced concrete lining and the stress of the lining structure during the water filling process, and do not focus on the flow of high-pressure water in the gap between the lining and the surrounding rock after the lining cracks and the change of the contact state between the lining and the surrounding rock, and the change of the interaction and bearing characteristics of the lining and the surrounding rock during the draining process.

[0006] Because the existing model test device cannot effectively monitor the width change process of the lining crack, the engineering designers and construction personnel cannot master the real running working characteristics of the reinforced concrete lining pressure tunnel during the filling and draining process, and the change of the interaction and bearing characteristics of the lining and the surrounding rock during the filling and draining process.

[0007] Therefore, in order to ensure the safety and rationality of the design of the reinforced concrete lining pressure tunnel, a device for simulating the filling and draining test of the concrete lining pressure tunnel after cracking is urgently needed to test whether the running working characteristics of the concrete pressure tunnel under the working conditions of filling and draining after cracking meet the design requirements, and to provide valuable reference for the design of the concrete lining pressure tunnel. SUMMARY

[0008] In view of the deficiencies of the existing high-water-head concrete lining pressure tunnel physical model test and test device, the purpose of the present application is to provide a reinforced concrete (reinforced concrete) lining pressure tunnel filling and draining test device and test method containing a prefabricated crack. The test device can simulate the filling and draining working state of the reinforced concrete lining pressure tunnel after cracking, accurately capture the change of the lining crack width of the reinforced concrete lining pressure tunnel during the filling and draining process, and thus reveal the dynamic evolution process of the water exosmosis evolution in the pressure tunnel, the stress of the lining structure and the contact state between the lining and the surrounding rock.

[0009] To achieve the above purpose, the following technical scheme is adopted in the present application: a reinforced concrete lining pressure tunnel filling and draining test device containing a prefabricated crack, which is composed of a cylindrical barrel, a reinforced concrete lining containing a prefabricated crack, surrounding rock, geotextile, a front flange plate, a rear flange plate and monitoring instruments.

[0010] The cylindrical barrel is a rigid metal cylinder, and the wall thickness d threshold The following requirements are met:

[0011] d threshold ≥1.05d (1)

[0012] wherein d threshold and d are the design value and the standard value of the wall thickness of the cylindrical shell (m) respectively; wherein d is determined by the following formula:

[0013]

[0014] wherein r s is the outer diameter of the cylindrical shell, in m; is the ultimate tensile strength of the steel used for the cylindrical shell, in MPa; p t is the design water head of the pressure tunnel, in MPa;

[0015] The surrounding rock is next to the inner wall of the cylindrical shell, and the inner side of the surrounding rock is the reinforced concrete lining containing prefabricated cracks; the front flange plate and the rear flange plate are fixed at both ends of the cylindrical shell respectively to form a closed internal water loading cavity which can be filled and drained;

[0016] The monitoring instrument includes a joint meter for monitoring the change of the crack width during the filling and draining process, and a reinforcement meter, a strain meter, a osmometer and a earth pressure meter for monitoring the operation condition of the pressure tunnel; the monitoring instrument is arranged in the inner wall of the crack, the reinforced concrete lining and between the reinforced concrete lining and the surrounding rock;

[0017] The geotextile is laid between the surrounding rock and the reinforced concrete lining; the thickness of the geotextile should make the hoop stress σ θ and the hoop strain ε θ of the reinforced concrete lining containing prefabricated cracks satisfy the following relationship:

[0018] σ θ1 <σ θ <σ θ2 (3)

[0019] ε θ1 <ε θ <ε θ2 (4)

[0020] Wherein σ θ1 and ε θ1 are the hoop stress and the hoop strain of the outer wall of the reinforced concrete lining containing prefabricated cracks under the rigid constraint of the lining;

[0021] σ θ2 and ε θ2 are the hoop stress and the hoop strain of the outer wall of the reinforced concrete lining containing prefabricated cracks when the outer wall is a free boundary;

[0022] wherein σ θ1 and ε θ1 , σ θ2 and ε θ2 may be determined according to the following formula:

[0023]

[0024]

[0025]

[0026]

[0027] wherein p crack is an estimated internal water pressure value (MPa) of the pressure tunnel lining cracking, and is 1.1 MPa;

[0028] a is an internal diameter of the prefabricated crack-containing reinforced concrete lining; b is an external diameter of the prefabricated crack-containing reinforced concrete lining; and r is a distance from any point of the prefabricated crack-containing reinforced concrete lining to the center of the circle;

[0029] υ is a Poisson's ratio of the prefabricated crack-containing reinforced concrete lining material;

[0030] E is an elastic modulus of the prefabricated crack-containing reinforced concrete lining material.

[0031] Preferably, the prefabricated crack-containing reinforced concrete lining is formed by concrete pouring and curing; and a plurality of hoop steels are arranged at intervals on the inner wall of the reinforced concrete lining perpendicularly to the longitudinal axis of the pressure tunnel, and a plurality of longitudinal steels are arranged at intervals on the inner wall of the reinforced concrete lining parallel to the longitudinal axis of the pressure tunnel.

[0032] A crack is pre-set on the inner wall of the reinforced concrete lining.

[0033] Preferably, five monitoring sections A-A, B-B, C-C, D-D and E-E perpendicular to the axis of the pressure tunnel are selected at intervals along the axis of the pressure tunnel in the prefabricated crack-containing reinforced concrete lining.

[0034] The joint meter is arranged at the crack of the monitoring section containing the prefabricated crack.

[0035] The 0° direction is taken as the center of the top of the cylindrical barrel, and the reinforcement meter and the strain meter are arranged at the positions of 350°, 20°, 90°, 135° and 180° of the monitoring sections A-A, B-B, C-C, D-D and E-E in the clockwise direction, respectively; and the distances from the reinforcement meter and the strain meter on each monitoring section to the central axis of the pressure tunnel are equal.

[0036] The earth pressure gauges and osmotic pressure gauges are arranged on the outer wall of the lining at positions of 340°, 5°, 90°, 135° and 180° of the monitoring sections of A-A, B-B, C-C, D-D and E-E respectively in a clockwise direction with the center of the top of the cylindrical barrel as a 0° direction, and the interval between the two is 6 cm.

[0037] Preferably, the reinforcement meter is bundled or welded on the ring-shaped reinforcement; the strain gauge is embedded in the reinforced concrete lining; and the earth pressure gauge and osmotic pressure gauge are arranged on the outer wall of the reinforced concrete lining.

[0038] Preferably, the depth of the crack is 6 cm, and the distance between the two ends of the crack and the end of the cylindrical barrel is 15 cm.

[0039] Preferably, the outer side of the front flange plate is provided with a plurality of stiffening ribs, and bolt holes for connecting with the cylindrical barrel are formed on the stiffening ribs; a pressure gauge is installed at the middle region of the front flange plate corresponding to the hole of the pressure tunnel, and an inner water loading connector and a cable outlet hole are arranged.

[0040] The outer side of the rear flange plate is provided with a plurality of stiffening ribs, and bolt holes for connecting with the cylindrical barrel are formed on the stiffening ribs; an inner cavity drainage connector is arranged at the middle region of the rear flange plate corresponding to the hole of the pressure tunnel.

[0041] A sealing ring is additionally arranged between the front flange plate, the rear flange plate and the cylindrical barrel.

[0042] The method for carrying out the pressure tunnel water filling and drainage test by using the above-mentioned prefabricated crack reinforced concrete lining pressure tunnel water filling and drainage test device comprises the following steps:

[0043] S1, gradually filling and draining water in the inner water loading cavity formed by the test device to simulate the water pressure loading and unloading working state in the pressure tunnel;

[0044] The pressurized water pump is connected to the inner water loading connector of the front flange plate to gradually fill water in the inner water loading cavity, and when the gradual filling stage is completed, the inner cavity drainage connector of the rear flange plate is opened to gradually drain water;

[0045] The number of steps, the total number of steps and the total number of steps of the water filling and drainage when the water filling pressure is 0.5 Mpa are as follows:

[0046]

[0047]

[0048] S total = 2 × S (11)

[0049] In the formula: S1 is the number of steps of water filling pressure equal to 0.5Mpa, S is the total number of water filling steps; S total The total number of water filling and draining; p1 is the water filling pressure of 0.5Mpa, p t The design water head of pressure tunnel, the unit is MPa, the value is 1.5MPa, and Δp is the loading and unloading amplitude of step-by-step water filling and draining pressure, the unit is MPa, the value is 0.05MPa;

[0050] When the step-by-step water filling and draining is carried out on the internal water loading cavity, the time length of each step water filling and draining pressure or pressure relief is:

[0051]

[0052] In the formula: T k The time length of k step water filling and draining pressure or pressure relief, k is the number of step-by-step water filling and draining;

[0053] During the step-by-step water filling and draining process of the internal water loading cavity, the pressure display number is read, and the internal water pressure change is recorded;

[0054] S3, during the step-by-step water filling and draining process of the internal water loading cavity, the change of the crack width of the reinforced concrete lining with prefabricated cracks is recorded in real time;

[0055] S3, during the step-by-step water filling and draining process of the internal water loading cavity, the test data collected by the reinforcement meter, strain gauge, osmotic pressure gauge and earth pressure gauge, such as the stress of the lining steel bar, the concrete hoop strain, the seepage field, the contact force between the lining and the surrounding rock, are recorded in real time.

[0056] Compared with the existing pressure tunnel physical model test technology, the present application has the following advantages:

[0057] (1), the present application can effectively capture the crack width change process of the reinforced concrete lining pressure tunnel after the lining cracks in the water filling and draining operation process, and solves the problem that the previous reinforced concrete lining pressure tunnel physical model test can only obtain the crack width when there is no internal and external water pressure at the end of the test, and cannot obtain the crack width evolution process in the whole test process.

[0058] (2), the present application lays geotextile between the reinforced concrete lining with prefabricated cracks and the surrounding rock, which can realize the rapid filling of high internal water into the contact part of the lining and the surrounding rock along the crack after the lining cracks, and truly reflects the situation that the high internal water flows into the contact part of the lining and the surrounding rock along the crack after the lining cracks in the actual project.

[0059] (3), the present application can be according to the position of prefabricated crack, through the corresponding layout joint meter, strain meter, reinforcement meter, osmotic pressure meter and earth pressure meter and other monitoring instrument, accurately capture the reinforced concrete lining pressure tunnel in the process of drainage operation lining crack width, internal water exosmosis, lining structure stress, and the dynamic evolution characteristics of lining and surrounding rock contact state, can reflect the mutual feedback process between the four and the collaborative working mechanism of reinforced concrete lining and surrounding rock of high water head pressure tunnel. BRIEF DESCRIPTION OF DRAWINGS

[0060] Figure 1 is the three-dimensional structure schematic diagram of the present application containing prefabricated crack reinforced concrete lining pressure tunnel filling and drainage test device;

[0061] Figure 2 is the longitudinal section structure schematic diagram of the present application pressure tunnel filling and drainage test device;

[0062] Figure 3 is the present application Figure 2 pressure tunnel filling and drainage test device transverse I-I section structure schematic diagram;

[0063] Figure 4 is the present application Figure 2 pressure tunnel filling and drainage test device transverse II-II section structure schematic diagram;

[0064] Figure 5 is the present application pressure tunnel filling and drainage test device cylindrical barrel structure schematic diagram;

[0065] Figure 6A is the present application internal mold structure schematic diagram for pouring reinforced concrete lining containing prefabricated crack;

[0066] Figure 6B is the present application external mold structure schematic diagram for pouring reinforced concrete lining containing prefabricated crack;

[0067] Figure 6C is the present application combined mold structure schematic diagram for pouring reinforced concrete lining containing prefabricated crack;

[0068] Figure 7 is the present application monitoring section position schematic diagram;

[0069] Figure 8A is the present application Figure 7 A-A monitoring section monitoring instrument arrangement position schematic diagram;

[0070] Figure 8B is the present application Figure 7 B-B monitoring section monitoring instrument arrangement position schematic diagram;

[0071] Figure 8C is the present applicationFigure 7 Monitoring instrument arrangement position diagram of monitoring section in the middle of C-C

[0072] Figure 8D The present application is Figure 7 Monitoring instrument arrangement position diagram of monitoring section in the middle of D-D

[0073] Figure 8E The present application is Figure 7 Monitoring instrument arrangement position diagram of monitoring section in the middle of E-E

[0074] Figure 9A The present application is

[0075] Figure 9B The present application is

[0076] Figure 10A The present application is

[0077] Figure 10B The present application is

[0078] Figure 11 The present application is

[0079] Figure 12 The present application is

[0080] 1, cylindrical barrel, 11 lug, 111 bolt connection hole, 12 cable outlet, 121 top flange, 122 cable outlet hole, 123 sealing gasket, 13 base; 2, pre-crack reinforced concrete lining, 21 hoop reinforcement, 22 longitudinal reinforcement, 23 crack; 3, surrounding rock; 4, geotextile; 5, front flange, 51 stiffener, 52 bolt hole, 53 pressure gauge, 54 internal water loading joint, 55 cable outlet hole; 6, rear flange, 61 stiffener, 62 bolt hole, 63 internal cavity drainage joint; 7, internal mold, 71 vertical steel plate; 8, pre-crack reinforced concrete lining pouring outer mold; 91 reinforcement meter, 92 strain gauge, 93 joint meter, 94 osmotic pressure meter, 95 earth pressure meter; 101 sealing ring, 102 through screw. DETAILED DESCRIPTION

[0081] The present application will be further illustrated by the following examples and figures, which should be understood as merely illustrating the present application and not limiting the scope of the present application. After reading the present application, those skilled in the art can make various modifications to the present application, which fall within the scope of the appended claims.

[0082] As Figures 1-5 The prefabricated crack reinforced concrete lining pressure tunnel water filling and draining test device disclosed by the present application is a cylindrical pressure cylinder, which is composed of a cylindrical cylinder body 1, a reinforced concrete lining 2 with prefabricated cracks, surrounding rock 3, geotextile 4, front flange plate 5, rear flange plate 6 and various monitoring instruments.

[0083] The cylindrical cylinder body 1 is a rigid metal cylinder, and the two ends of the cylindrical cylinder body 1 are provided with lugs 11 for connecting with the front and rear flange plates 5 and 6, and a plurality of bolt connection holes 111 are formed on the lugs 11 at intervals. A cable outlet 12 is arranged on the top of the cylindrical cylinder body 1, and a fixing foot 13 is arranged on the bottom of the cylindrical cylinder body 1.

[0084] During the water filling test, the cylindrical cylinder body needs to bear the water pressure, so the wall thickness of the cylindrical cylinder body should meet the following requirements:

[0085] d threshold ≥1.05d (1)

[0086] In the formula, d threshold and d are the design value and standard value (unit: m) of the wall thickness of the cylindrical cylinder body, respectively; wherein d is determined by the following formula:

[0087]

[0088] In the formula, r s is the outer diameter (m) of the cylindrical cylinder body; is the ultimate tensile strength (MPa) of the steel material used by the cylindrical cylinder body; p t is the design water head (MPa) of the pressure tunnel.

[0089] In the preferred embodiment of the present application, the cylindrical cylinder body 1 is an iron cylinder with a length of 1.0 meter, a diameter of 1.5 meters and a wall thickness of 2 centimeters.

[0090] The surrounding rock 3 is arranged next to the inner wall of the cylindrical cylinder body 1, and the surrounding rock 3 is formed by pouring and curing high-grade concrete. In the preferred embodiment of the present application, the surrounding rock 3 is formed by pouring concrete, and the thickness of the surrounding rock 3 is 23 centimeters.

[0091] The inner side of the surrounding rock 3 is the reinforced concrete lining 2. The reinforced concrete lining 2 is formed by pouring and curing concrete; a plurality of hoop steels 21 are arranged at intervals vertically to the longitudinal axis of the tunnel inside the reinforced concrete lining 2, and a plurality of longitudinal steels 22 are arranged at intervals parallel to the longitudinal axis of the tunnel. In order to study the dynamic evolution process of each physical characteristic during the water filling and draining operation of the pressure tunnel after the cracks generated by the cracking of the concrete lining of the pressure tunnel, a crack 23 parallel to the longitudinal axis of the pressure tunnel is prearranged on the inner wall of the reinforced concrete lining of the pressure tunnel in the preferred embodiment of the present application, the depth h1 of the crack 23 is 6 centimeters, and the distance d1 from the two ends of the crack 23 to the end of the cylindrical cylinder body is 15 centimeters. (See Figure 6A).

[0092] Figure 6A is the internal mold structure diagram of the present application for pouring the reinforced concrete lining with prefabricated cracks, Figure 6B is the external mold structure diagram of the present application for pouring the reinforced concrete lining with prefabricated cracks, Figure 6C is the structure diagram of the internal and external mold combination. As shown in Figures 6A-6C , a vertical steel plate 71 is arranged on the outer wall of the internal mold 7 for pouring the lining, which is parallel to the axis of the pressure tunnel, and is used to form the prefabricated cracks 23 during pouring the lining. The width h1 of the vertical steel plate 71 is 6 cm, and the distance d1 from the ends of the internal mold 7 is 15 cm. The vertical steel plate 71 can be welded on the outer wall of the internal mold 7, or can be fixed on the outer wall of the internal mold by bolts and nuts. When pouring the concrete lining 2, the internal mold 7, the external mold 8 and the rear flange plate 6 are assembled to form a combined mold for pouring the concrete lining, the inner diameter of the internal mold 7 and the external mold 8 and the distance between them can be adjusted according to the thickness of the reinforced concrete lining 2 to be poured, then the hoop reinforcement 21 and the longitudinal reinforcement 22 are bound between the internal and external molds, then the concrete is poured to form the reinforced concrete lining pressure tunnel with prefabricated cracks.

[0093] After the pressure tunnel is filled with water, the reinforced concrete lining 2 cracks along the prefabricated cracks 23. In order to ensure that the internal water in the pressure tunnel seeps out along the cracks 23 after the concrete lining cracks, enters the lining, and quickly flows between the lining 2 and the surrounding rock 3 when it reaches there, rather than further entering the surrounding rock 3, which will eventually cause the surrounding rock 3 to separate from the lining 2, and prevent new cracks in the reinforced concrete lining 2 during the subsequent water filling process of the pressure tunnel, affecting the change of the width of the prefabricated cracks 23, and further affecting the analysis of the dynamic evolution process of the water seepage in the pressure tunnel, the lining structure stress and the contact state between the lining and the surrounding rock caused by the change of the width of the cracks 23, the present application lays a layer of geotextile 4 between the outer wall of the reinforced concrete lining 2 with prefabricated cracks and the inner wall of the surrounding rock 3.

[0094] The thickness of the geotextile 4 should make the hoop stress σ θ and the hoop strain ε θ of the reinforced concrete lining 2 with prefabricated cracks satisfy the following relationship:

[0095] σ θ1 <σ θ <σ θ2 (3)

[0096] ε θ1 <ε θ <ε θ2 (4)

[0097] wherein, σθ1 and ε θ1 respectively are the circumferential stress and circumferential strain of the outer wall of the prefabricated crack reinforced concrete lining under rigid constraint;

[0098] σ θ2 and ε θ2 respectively are the circumferential stress and circumferential strain of the outer wall of the prefabricated crack reinforced concrete lining under rigid constraint.

[0099] wherein σ θ1 and ε θ1 , σ θ2 and ε θ2 can be determined according to the following formula:

[0100]

[0101]

[0102]

[0103]

[0104] In the formula, p crack is the estimated cracking internal water pressure value of the pressure tunnel lining (MPa), and is 1.1 MPa;

[0105] a is the inner diameter of the prefabricated crack reinforced concrete lining; b is the outer diameter of the prefabricated crack reinforced concrete lining; and r is the distance from any point of the prefabricated crack reinforced concrete lining to the center of the circle.

[0106] υ is the Poisson's ratio of the material of the prefabricated crack reinforced concrete lining;

[0107] E is the elastic modulus of the material of the prefabricated crack reinforced concrete lining.

[0108] In the preferred embodiment of the present application, the geotextile 4 is laid on the outer wall of the prefabricated crack reinforced concrete lining 2 and is pasted with flexible adhesive.

[0109] The present application induces the lining to crack from the prefabricated crack 23 in the reinforced concrete lining 2, in order to accurately capture the pressure tunnel's water filling and draining working state after the reinforced concrete lining cracks, observe and analyze the crack width change, and the dynamic change process of the pressure tunnel's physical properties possibly caused by the crack width change, the present application arranges various monitoring instruments in the reinforced concrete lining, including but not limited to a plurality of steel gauges 91, strain gauges 92, joint meters 93, osmotic pressure gauges 94 and earth pressure gauges 95. The arranged joint meters 93 are used to monitor the crack 23 width change during the water filling and draining process, and the present application arranges the steel gauges 91, strain gauges 92, osmotic pressure gauges 94 and earth pressure gauges 95 according to the position of the prefabricated crack 23 to capture the operation working characteristics of the pressure tunnel during the water filling and draining process.

[0110] As shown in Figure 7 , in order to obtain the test data of the steel stress, the concrete hoop strain, the lining crack width change, the seepage field, the contact force between the lining and the surrounding rock, etc. during the water filling and draining process of the pressure tunnel, the present application selects five monitoring sections A-A, B-B, C-C, D-D and E-E perpendicular to the axis of the pressure tunnel along the axis direction of the pressure tunnel in the reinforced concrete lining containing the prefabricated crack.

[0111] As shown in Figures 8B-8D , the joint meters 93 are arranged at the crack 23 of the monitoring sections, such as the B-B, C-C and D-D monitoring sections.

[0112] As shown in Figures 8A-8E , the 0° direction is taken at the center of the top of the cylindrical barrel 1, and one steel gauge 91 is arranged at the 350°, 20°, 90°, 135° and 180° positions of the A-A, B-B, C-C, D-D and E-E monitoring sections in the clockwise direction, respectively. The distance between the steel gauges 91 on each monitoring section and the central axis of the pressure tunnel is equal. In the embodiment of the present application, only one steel gauge can be arranged on each monitoring section, for example, one steel gauge is arranged at the 350° of the A-A monitoring section, one steel gauge is arranged at the 20° of the B-B monitoring section, one steel gauge is arranged at the 90° of the C-C monitoring section, one steel gauge is arranged at the 135° of the D-D monitoring section, and one steel gauge is arranged at the 180° of the E-E monitoring section; or one steel gauge can be arranged at the 350°, 20°, 90°, 135° and 180° positions of each monitoring section, respectively.

[0113] With the center of the top of the cylindrical barrel 1 as the 0° direction, one strain gauge 92 is arranged at the 350°, 20°, 90°, 135° and 180° positions of the A-A, B-B, C-C, D-D and E-E monitoring sections respectively in the clockwise direction, and the distances of the strain gauges 92 on each monitoring section from the central axis of the pressure tunnel are equal. In the embodiment of the present application, one strain gauge 92 can be arranged at each monitoring section, for example, one strain gauge is arranged at the 350° of the A-A monitoring section, one strain gauge is arranged at the 20° of the B-B monitoring section, one strain gauge is arranged at the 90° of the C-C monitoring section, one strain gauge is arranged at the 135° of the D-D monitoring section, and one strain gauge is arranged at the 180° of the E-E monitoring section; or one strain gauge can be arranged at the 350°, 20°, 90°, 135° and 180° positions of each monitoring section respectively.

[0114] Similarly, with the center of the top of the cylindrical barrel 1 as the 0° direction, one earth pressure gauge 94 and one osmotic pressure gauge 95 are arranged on the outer wall of the lining 2 at the 340°, 5°, 90°, 135° and 180° positions of the A-A, B-B, C-C, D-D and E-E monitoring sections respectively in the clockwise direction, and the arrangement interval of the two is 6 cm.

[0115] In the embodiment of the present application, one earth pressure gauge 94 and one osmotic pressure gauge 95 can be arranged at each monitoring section, for example, one earth pressure gauge 94 and one osmotic pressure gauge 95 are arranged at the 340° of the A-A monitoring section, one earth pressure gauge 94 and one osmotic pressure gauge 95 are arranged at the 5° of the B-B monitoring section, one earth pressure gauge 94 and one osmotic pressure gauge 95 are arranged at the 90° of the C-C monitoring section, one earth pressure gauge 94 and one osmotic pressure gauge 95 are arranged at the 135° of the D-D monitoring section, and one earth pressure gauge 94 and one osmotic pressure gauge 95 are arranged at the 180° of the E-E monitoring section; or one earth pressure gauge 94 and one osmotic pressure gauge 95 can be arranged at the 340°, 5°, 90°, 135° and 180° positions of each monitoring section respectively.

[0116] Before pouring the reinforced concrete lining containing the prefabricated cracks, the steel meter 91 is tied or welded on the ring-shaped steel 21, the strain gauge 92 is connected to the outer wall of the lining inner mold 7 or the inner wall of the lining outer mold 8 through the connecting piece; the earth pressure gauge 95 and the osmotic pressure gauge 96 are fixed on the inner wall of the lining outer mold 8 through the connecting piece. After pouring the reinforced concrete lining, the joint meter 93 is fixed on the inner wall of the prefabricated crack 23.

[0117] In order to simulate the water filling and draining working state of the pressure tunnel, the water in the pressure tunnel is drained, and the water in the water tank 6 is poured into the pressure tunnel through the water inlet pipe 5. Figure 1 , Figure 2As shown, the present application is connected and fixed with front flange plate 5 and rear flange plate 6 at both ends of cylindrical barrel 1. Inner wall of reinforced concrete lining 2 with prefabricated cracks forms a closed inner water loading cavity which can be filled and drained with front flange plate 5 and rear flange plate 6. As shown in Figure 9A and Figure 9B As shown, outer side of front flange plate 5 is provided with several stiffening ribs 51, and bolt holes 52 for connecting with cylindrical barrel 1 are opened on stiffening ribs 51. Pressure gauge 53 is installed at middle area of front flange plate 5 corresponding to hole of pressure tunnel, and inner water loading joint 54 and cable outlet hole 55 are provided. As shown in Figure 10A and Figure 10B As shown, outer side of rear flange plate 6 is also provided with several stiffening ribs 61, and bolt holes 62 for connecting with cylindrical barrel 1 are opened on stiffening ribs 61. Inner cavity drainage joint 63 is provided at middle area of rear flange plate 6 corresponding to hole of pressure tunnel.

[0118] In order to enhance sealing, sealing ring is additionally provided between front flange plate 5, rear flange plate 6 and cylindrical barrel 1, and front and rear flange plates are further connected through through-hole screw rod 10 passing through hole of pressure tunnel.

[0119] During test, inner water fills inner water loading cavity through inner water loading joint 54 of front flange plate, that is, is injected into pressure tunnel, and is discharged through inner cavity drainage joint 63 of rear flange plate after test. During whole test process, various monitoring instruments monitor dynamic evolution characteristics of inner water exosmosis of reinforced concrete lining pressure tunnel during filling and draining process, stress of lining structure, change of lining crack width and dynamic evolution characteristics of contact state of lining and surrounding rock, so as to clarify mutual feedback process of four, and reveal cooperative working mechanism of reinforced concrete lining of high water head pressure tunnel and surrounding rock.

[0120] Power line and data line of various monitoring instruments buried in lining are led out from cable outlet hole 55 of front flange plate and cable outlet 12 at top of cylindrical barrel 1 according to principle of nearness. As shown in Figure 11 Cable outlet 12 at top of cylindrical barrel 1 is fixed with top flange plate 121 through bolt, cable outlet hole 122 is opened on top flange plate 121, and sealing pad 122 is additionally provided between top flange plate 121 and cable outlet 12.

[0121] Method for carrying out pressure tunnel filling and draining test by using above-mentioned reinforced concrete lining pressure tunnel filling and draining test device comprises following steps:

[0122] S1, inner water loading cavity formed by test device is filled and drained step by step to simulate water pressure loading and unloading working state in pressure tunnel;

[0123] The pressurized water pump is connected to the inner water loading joint 54 of the front flange plate, and the inner water loading cavity is gradually filled with water as shown in Figure 12 When the gradual filling stage ends, the inner cavity drainage joint 63 of the rear flange plate is opened for gradual drainage.

[0124] The number of steps, the total number of steps, and the total number of steps of filling and draining at a filling pressure of 0.5 Mpa are as follows:

[0125]

[0126]

[0127] S total = 2 x S (11)

[0128] In the formula: S1 is the number of steps at a filling pressure of 0.5 Mpa, S is the total number of steps of filling, and S total is the total number of steps of filling and draining; p1 is the filling pressure of 0.5 Mpa, p t is the design water head of the pressure tunnel (MPa), which is 1.5 MPa, and Δp is the loading and unloading amplitude of the gradual filling and draining pressure (MPa), which is 0.05 MPa.

[0129] When the inner water loading cavity is gradually filled and drained, the duration of each step of filling and draining pressure or pressure relief is:

[0130]

[0131] In the formula: T k is the duration of the kth step of filling and draining pressure or pressure relief, and k is the number of steps of gradual filling and draining.

[0132] During the gradual filling and draining of the inner water loading cavity, the pressure gauge 53 is read and the change of the inner water pressure is recorded;

[0133] S3, during the gradual filling and draining of the inner water loading cavity, the change of the crack width of the reinforced concrete lining with precast cracks is recorded in real time;

[0134] S3, during the gradual filling and draining of the inner water loading cavity, the test data collected by the reinforcement meter, strain gauge, osmotic pressure gauge, and soil pressure gauge, such as the stress of the lining steel, the circumferential strain of the concrete, the seepage field, and the contact force between the lining and the surrounding rock, are recorded in real time.

[0135] Compared with the prior art, the present application induces the lining to crack from the prefabricated crack in the reinforced concrete lining, so that not only the change of the crack width during the water filling and discharging process can be monitored by arranging a joint meter, but also the operation working properties during the water filling and discharging process of the pressure tunnel can be accurately captured according to the position of the prefabricated crack and by arranging monitoring instruments such as strain gauges, reinforcement gauges, osmotic pressure gauges and earth pressure gauges. In addition, a certain thickness of geotextile is arranged between the lining and the surrounding rock to ensure that the internal water flows quickly into the space between the lining and the surrounding rock after the internal water exosmosis along the crack after the lining cracks, so that the lining is converted from tension to compression, new cracks of the lining are prevented during the subsequent water filling process, and the change rule of the prefabricated crack width is further affected. In order to study and analyze the dynamic evolution characteristics of the internal water exosmosis, the lining structure stress, the lining crack width and the contact state between the lining and the surrounding rock of the reinforced concrete lining pressure tunnel during the water filling and discharging process, clarify the mutual feedback process among the four, and reveal the basis for the cooperative working mechanism of the reinforced concrete lining and the surrounding rock of the high water head pressure tunnel.

[0136] Finally, it should be noted that: the above-described embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A test device for filling and draining a pressure tunnel with precast cracked reinforced concrete lining, characterized in that: It consists of a cylindrical body, a reinforced concrete lining with pre-fabricated cracks, surrounding rock, geotextile, a front flange, a rear flange, and monitoring instruments. The cylindrical body is a rigid metal cylinder with a wall thickness d. threshold The following requirements must be met: d threshold ≥1.05d (1) In the formula, d threshold Let and d be the design and standard values ​​(m) of the cylindrical shell wall thickness, respectively; where d is determined by the following formula: In the formula, r s The outer diameter of the cylindrical body is expressed in meters (m). The ultimate tensile strength of the steel used for the cylindrical body, in MPa; p t Design head for pressure tunnels, unit MPa; The inner wall of the cylindrical body is the surrounding rock, and the inner side of the surrounding rock is the reinforced concrete lining containing pre-fabricated cracks; the front flange and the rear flange are respectively fixed at both ends of the cylindrical body to form a closed, fillable and drainable internal water loading cavity. The monitoring instruments include a crack gauge for monitoring the changes in crack width during filling and drainage, and a steel bar gauge, strain gauge, piezometer, and earth pressure gauge for monitoring the operation of the pressure tunnel; the monitoring instruments are deployed on the inner wall of the crack, inside the reinforced concrete lining, and between the reinforced concrete lining and the surrounding rock. The geotextile is laid between the surrounding rock and the reinforced concrete lining; the thickness of the geotextile should be such that the circumferential stress σ of the reinforced concrete lining containing precast cracks is reduced. θ and circumferential strain ε θ Satisfy the following relations: s θ1 <s θ <s θ2 (3) e θ1 <e θ <e θ2 (4) Where, σ θ1 and ε θ1 The values ​​represent the circumferential stress and circumferential strain of the outer wall of the reinforced concrete lining with precast cracks under rigid constraints. σ θ2 and ε θ2 The values ​​represent the circumferential stress and circumferential strain of the reinforced concrete lining with precast cracks when the outer wall is a free boundary. Where, σ θ1 and ε θ1 σ θ2 and ε θ2 Determined according to the following formula: In the formula: p crack The value is the estimated internal water pressure in the lining of the pressure tunnel, expressed in MPa. a is the inner diameter of the reinforced concrete lining with precast cracks; b is the outer diameter of the reinforced concrete lining with precast cracks; r is the distance from any point on the reinforced concrete lining with precast cracks to the center of the circle. υ represents the Poisson's ratio of the reinforced concrete lining material containing precast cracks; E represents the elastic modulus of the reinforced concrete lining material containing precast cracks.

2. The pressure tunnel filling and drainage test device with precast crack reinforced concrete lining according to claim 1, characterized in that: The reinforced concrete lining containing precast cracks is formed by concrete pouring and curing; several circumferential steel bars are arranged at intervals perpendicular to the longitudinal axis of the pressure tunnel, and several longitudinal steel bars are arranged at intervals parallel to the longitudinal axis of the pressure tunnel. A crack is pre-installed on the inner wall of the reinforced concrete lining.

3. The pressure tunnel filling and drainage test device with precast crack reinforced concrete lining according to claim 2, characterized in that: Within the reinforced concrete lining containing precast cracks, five monitoring sections AA, BB, CC, DD, and EE, perpendicular to the axis of the pressure tunnel, are selected at intervals along the axis of the pressure tunnel. The crack gauge is installed at the crack in the monitoring section containing the pre-existing crack. With the center of the top of the cylindrical body as 0°, the steel bar gauge and the strain gauge are arranged in a clockwise direction at positions of 350°, 20°, 90°, 135°, and 180° on the monitoring sections AA, BB, CC, DD, and EE, respectively. The steel bar gauge and the strain gauge on each monitoring section are equidistant from the central axis of the pressure tunnel. With the center of the top of the cylindrical body as 0°, the earth pressure gauge and permeability gauge are installed on the outer wall of the lining at positions of 340°, 5°, 90°, 135° and 180° on the monitoring sections AA, BB, CC, DD and EE, respectively, in a clockwise direction, with a spacing of 6cm between them.

4. The pressure tunnel filling and drainage test device with precast crack reinforced concrete lining according to claim 3, characterized in that: The reinforcing bars are bound or welded to the circumferential reinforcing bars; The strain gauge is embedded in the reinforced concrete lining; The earth pressure gauge and piezometer are installed on the outer wall of the reinforced concrete lining.

5. The pressure tunnel filling and drainage test device with precast crack reinforced concrete lining according to claim 4, characterized in that: The crack is 6 cm deep and the distance between its two ends and the end of the cylindrical body is 15 cm.

6. The pressure tunnel filling and drainage test device with precast crack reinforced concrete lining according to claim 5, characterized in that: Several stiffening ribs are provided on the outer side of the front flange, and bolt holes for connecting with the cylindrical body are opened on them; in the middle area of ​​the front flange, corresponding to the hole of the pressure tunnel, a pressure gauge is installed, and an internal water loading joint and a cable outlet hole are provided. The outer side of the rear flange is provided with several stiffening ribs, and bolt holes for connecting with the cylindrical body are provided on them; in the middle area of ​​the rear flange, an inner cavity drainage joint is provided at the location corresponding to the hole of the pressure tunnel. A sealing ring is added between the front flange, the rear flange and the cylindrical body.

7. A method for conducting pressure tunnel filling and drainage tests using the pressure tunnel filling and drainage test apparatus for reinforced concrete lining with precast cracks as described in any one of claims 1-6, comprising the following steps: S1. Gradually fill and drain water into the internal water loading chamber formed by the test device to simulate the working state of water pressure loading and unloading in a pressure tunnel. Connect the pressurized water pump to the internal water loading joint of the front flange to fill the internal water loading chamber with water step by step. After the step-by-step water filling stage is completed, open the internal drain joint of the rear flange to drain the water step by step. The number of water filling steps, the total number of water filling steps, and the total number of water filling and draining steps at a water pressure of 0.5 MPa are as follows: S total =2×S (11) In the formula: S1 is the number of steps when the water pressure is equal to 0.5 MPa, and S is the total number of water filling steps; S total p1 represents the total number of filling and draining steps; p1 is the filling pressure of 0.5 MPa. t The design head for the pressure tunnel is in MPa, and the value is taken as 1.5MPa. Δp is the loading and unloading amplitude of the staged filling and draining pressure, in MPa, and the value is taken as 0.05MPa. When performing staged filling and draining of the internal water loading chamber, the duration of pressurization or depressurization for each stage is as follows: In the formula: T k The duration of pressurization or depressurization for the k-th stage of filling and draining, where k is the number of steps in the stage of filling and draining. During the process of gradually filling and draining the internal water loading chamber, read the pressure gauge readings and record the changes in internal water pressure. S3. During the process of gradually filling and draining the internal water loading cavity, record the changes in the width of the reinforced concrete lining cracks containing precast cracks in real time. S3. During the process of gradually filling and draining the internal water loading cavity, record in real time the test data of the steel reinforcement stress, concrete circumferential strain, seepage field, and contact force between the lining and the surrounding rock collected by the steel reinforcement gauge, strain gauge, piezometer, and earth pressure gauge.

Images