CN110243688B - Dry-hard concrete hydraulic splitting test piece and its implementation method - Google Patents

Abstract

The invention discloses a dry-hard concrete hydraulic splitting test piece and an implementation method, comprising a mold, a compacted dry-hard concrete and a seam-forming member. The seam-forming member includes a seam-forming sheet, a water inlet pipe and a water outlet pipe. The center position of the upper surface of the dry-hard concrete with half the capacity of the compaction mold. The seam sheet includes the upper seam sheet and the lower seam sheet with the same structure and is aligned up and down. The upper seam sheet includes the upper body, the upper bond The sealing tape and the upper gasket, the outer edge of the lower surface of the upper sheet body is covered with an adhesive sealing tape, the upper gasket is located on the inner ring of the upper adhesive sealing tape, and the lower seamed sheet includes the lower sheet body, the lower adhesive tape The sealing tape and the lower gasket, there are 6 to 10 identical spacers at intervals between the bonding surfaces of the upper adhesive sealing tape and the lower adhesive sealing tape. The upper and lower gaskets are made of water-permeable materials. There are free water-filled pores between the gaskets, one end of the water inlet pipe and the water outlet pipe extends into the inner ring of the upper and lower adhesive sealing tapes, and the other ends of the water inlet pipe and the water outlet pipe respectively extend from the two mutually corresponding side walls of the mold. stretch out.

Description

Dry-hard concrete hydraulic splitting test piece and its implementation method

technical field

The invention belongs to the technical field of hydraulic engineering testing, in particular to a dry-hard concrete hydraulic splitting test piece and an implementation method.

Background technique

Hydraulic splitting of rock mass or concrete is a physical phenomenon in which cracks expand and penetrate under the action of high water head, thereby changing the structure of rock mass or concrete. Hydraulic fracturing plays an important role in geological engineering such as natural gas extraction, nuclear waste storage, and geothermal development. However, under the action of high water pressure, serious damage to rock mass slopes and hydraulic concrete buildings often occurs. Slope instability, the collapse of the St. Francis gravity dam in the United States, and the inflow of water in the long-exploration tunnel of the Jinping II Hydropower Station on the Yalong River in my country are all accidents caused by hydraulic splitting.

At present, the construction of high-reservoir dams has risen to a new level. With the increase of dam height, the problem of hydraulic splitting of hydraulic concrete structures under the action of high-pressure water is more prominent. The direct consequence is the expansion of cracks and the seepage of the dam body. Leakage, which not only reduces the durability of concrete, but also reduces the strength of the structure, which not only affects the normal use of the building, but also threatens the safe operation of the dam. With the construction of high concrete dams, many scholars have carried out research on the influence of hydraulic splitting on the cracking of high dams in combination with specific projects. In the beginning, some scholars carried out hydraulic splitting test based on the improvement of traditional confining pressure triaxial test in the geotechnical field. Due to the limitation of pressure-holding equipment, the size of the specimen is small, and only concrete or mortar specimens with small aggregates can be performed. The splitting test was carried out, and a well hole was set in the specimen, and high-pressure water was added to the well hole until the specimen split, which is not completely consistent with the hydraulic splitting phenomenon of most single cracks in concrete. Later, related researchers borrowed and improved the compact tensile specimen in the fracture study of metal materials, using the hydraulic splitting test based on concrete wedging into the splitting specimen, cutting cracks on one side of the concrete specimen, and then setting the cracks around the cracks. The water-tight device seals the cracks, and then applies high-pressure water in the cracks to simulate the splitting test of a single crack of concrete. Some research results have been obtained in the hydraulic splitting of concrete. In recent years, some scholars have further improved the hydraulic splitting test method, using the method of forming preset cracks inside the concrete specimen, relying on the concrete itself to withstand high pressure water, and carrying out a stress-free, biaxial force applied hydraulic splitting simulation experiment of concrete members , which is closer to the actual engineering state. In the prior art, pre-embedded components are usually used in concrete specimens to form reserved joints, and then high-pressure water is passed through the inlet and outlet pipes to conduct hydraulic splitting tests. For example, in a rigid joint-forming device, by fixing The component fixes the seam-forming device and the concrete mold together, the seam-forming sheet is rigid, and then concrete is poured. At this time, the concrete needs to have a certain fluidity; there is also an elastic seam-forming device that also fixes the seam-forming device on the concrete mold through the fixing member. , the seam-forming sheet is elastic, and a seam space is formed by placing the elastic sealing bag on the frame. When the tie of the elastic sealing bag is released under the action of water pressure, the elastic sealing bag will block the side wall of the seam. , the water pressure will not all act on the side wall of the joint, which has a great influence on the results of the pressure test, which is not very accurate. This structure also requires a certain fluidity of the concrete. In the prior art, the structural form of the internal jointed components of concrete hydraulic splitting is fine, which can meet the test requirements of certain concrete. However, the problem of concrete hydraulic splitting in actual engineering is very complicated, and the mechanism of hydraulic splitting has not been thoroughly studied. It is not possible to fully simulate the real situation of concrete hydraulic splitting. Especially in the research on the hydraulic splitting of dry-hard concrete such as roller compacted concrete, since the concrete does not have fluidity, it is necessary to adopt the method of rolling compaction to form the hydraulic splitting specimen, and the structural form of the jointed member is strictly required. The seam-forming members in the technology do not meet the demand.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a dry-hard concrete hydraulic splitting test piece and an implementation method, the simulation of which is more realistic and reliable.

In order to achieve the above object, the present invention adopts the following technical solutions:

A dry-hard concrete hydraulic splitting test piece, which comprises a mold, compacted dry-hard concrete and a seam-forming member, the seam-forming member includes a seam-forming sheet, a water inlet pipe and a water outlet pipe, and the seam-forming member is located in a half of the mold. The center position of the upper surface of the compacted dry-hard concrete with the capacity of tamping, the VC value of the dry-hard concrete is controlled at 2-25s, and the jointed piece includes an upper jointed piece and a lower jointed piece with the same structure. The upper jointed piece Aligned with the lower seam sheet, the upper seam sheet includes an upper sheet body, an upper adhesive sealing tape and an upper gasket, and the upper adhesive sealing tape is surrounded by the outer edge of the lower surface of the upper sheet body. , the upper gasket is located in the inner ring of the upper adhesive sealing tape, the lower seamed sheet includes a lower sheet body, a lower adhesive sealing tape and a lower gasket, and the outer edge of the upper surface of the lower sheet body is glued to the lower sheet Adhesive sealing tape, the lower gasket is located on the inner ring of the lower adhesive sealing tape, the lower surface of the upper adhesive sealing tape is bonded with the upper surface of the lower adhesive sealing tape, and the upper surface of the upper adhesive sealing tape is bonded. There are 6 to 10 identical spacers between the lower surface and the upper surface of the lower adhesive sealing tape. The upper and lower sheets are made of plastic material, their tensile strength is greater than 5MPa, and the softness should be It is 80-100mN, the upper and lower gaskets are made of water-permeable material, there are freely water-filled pores between the upper gasket and the lower gasket, and the outlet end of the water inlet pipe and the inlet end of the water outlet pipe pass through the upper gasket respectively. between the sealing tape and the lower bonding sealing tape and is located in the annular space where the inner rings of the upper and lower bonding sealing tapes are located, and is sealed and bonded with the upper and lower bonding sealing tapes, the inlet end of the water inlet pipe and the The outlet ends of the water outlet pipe respectively protrude from two opposite sides of the mold, and the outer wall surfaces of the water inlet pipe and the water outlet pipe are pockmarked surfaces.

Preferably, before the lower surface of the upper adhesive sealing tape is bonded to the upper surface of the lower adhesive sealing tape, between their bonding surfaces, 6 to 10 identical spacers are glued together. The length accounts for 1/3 to 1/2 of the circumference of the inner edge of the adhesive tape, and the width of the spacer should be the same as the distance from the inner edge to the outer edge of the adhesive tape or slightly larger by 1 to 2 mm.

Preferably, the water inlet and outlet pipes are L-shaped, the horizontal section of the water inlet pipe and the horizontal section of the water outlet pipe are arranged opposite to each other at an interval of 180 degrees, and the distance between the outlet end of the water inlet pipe and the inlet end of the water outlet pipe The edge of the inner ring of the lower adhesive sealing tape is 0.25-1.25mm.

Preferably, the upper annular gap between the upper gasket and the inner ring of the upper adhesive sealing tape is 0.5 mm to 1 mm, and the lower annular gap between the lower gasket and the inner ring of the lower adhesive sealing tape is 0.5mm to 1mm.

Preferably, the upper and lower sheet bodies are circular, the sealing adhesive tape is circular, and the upper and lower gaskets are circular.

Preferably, the upper and lower adhesive sealing tapes are double-sided adhesive tapes, and/or the upper and lower gaskets are filter paper.

Preferably, the thickness of the slotted sheet is 1-3 mm.

Preferably, the width of the upper and lower sealing adhesive tapes should be 1/5 to 1/7 of the size of the slotted sheet, and/or the size of the upper and lower sheets should be 1/2 to 1 of the size of the mold /5.

Preferably, the separator is a filter paper with a tensile strength of >100 kPa and a filtering effect on cement particles but free passage of water.

An implementation method comprising any of the above-mentioned dry-hard concrete hydraulic splitting specimen technical solutions, which mainly comprises the following steps:

(1) The steel mold is used as the mold for the hydraulic splitting specimen of the dry-hard concrete, the VC value of the dry-hard concrete is controlled at 2-25s, and the dry-hard concrete is formed by the tamping technique;

(2) First ram the dry hard concrete of half capacity in the compacted mold, put it into the jointed member, place the jointed piece horizontally in the center of the upper surface of the poured concrete, and bend the water inlet pipe and the water outlet pipe 90 degrees from the bottom of the mold respectively. The two diagonals are drawn vertically (for square molds) or are drawn vertically from both ends of a diameter line of the mold along the inner wall of the mold (for cylindrical molds), the water inlet of the water inlet pipe and the water outlet of the water outlet pipe are higher than The edge of the mold, seal the water inlet of the water inlet pipe and the water outlet of the water outlet pipe to prevent debris from entering;

(3) Then, around the seam sheet, the water inlet pipe and the water outlet pipe, mainly around and above the upper seam sheet, spread a little dry and hard concrete that removes large aggregates to avoid the formation of seams by large aggregates during the tamping process. If the sheet is damaged, lay the dry hard concrete with the remaining capacity of the mold, and at the same time, make the positions of the two diagonal openings of the square gasket under the tamper plate correspond to the water inlet pipe and the water outlet pipe at the two diagonal lead-out positions of the mold, (for Square mold) or the two opening positions of the circular gasket under the tamper plate at both ends of the same diameter line correspond to the lead-out positions of the water inlet pipe and the water outlet pipe along the inner wall of the mold at both ends of a certain diameter line of the mold (for The purpose is to prevent the gasket under the tamping plate from contacting the inlet and outlet pipes, and to protect the inlet and outlet pipes from being damaged during the tamping process. Manual stabilization of the water inlet and outlet pipes is required during tamping. , to flexibly control the position of the seam and prevent it from moving;

(4) The mold can be dismantled after standing for 24 hours. Immediately after dismantling the mold, test whether the water inlet and outlet pipes are smooth with water or air. If they are smooth, seal the water inlet and outlet pipes again and transport them to the curing room. , is discarded.

Beneficial effects of the present invention: The present invention provides a dry-hard concrete hydraulic splitting test piece and an implementation method. By forming a seam-shaped closed space to withstand high pressure water inside the dry-hard concrete hydraulic splitting test piece, the internal seam-forming member structural form Simple, simple to manufacture, reliable implementation method, no special fixing device is required, no interference of the fixing device to the forming of the specimen, reducing the influence of the fixing device on stress concentration when the crack is subjected to hydraulic pressure, and the high-quality rate of the prepared specimen high. The most important thing is to use a flexible seam-forming sheet, which can better fit the large aggregate inside the specimen to a certain extent, and is more in line with the actual crack structure. The space is filled with water, which can completely eliminate the interference of air. Compared with the tensile strength of concrete, the bonding force between the two joint pieces is extremely small. The two joint pieces can be separated under the action of very low water pressure to avoid hydraulic splitting. The test results cause errors, and before the lower surface of the upper adhesive sealing tape is bonded to the upper surface of the lower adhesive sealing tape, by surrounding the water-permeable spacer between their bonding surfaces, the high-pressure water can be real-time, Evenly acting on the front edge of dry-hard concrete cracks, the simulated high-pressure water splitting conditions are more realistic, and the implementation method is simple and reliable. The maximum water pressure that the dry-hard concrete hydraulic splitting test piece of the present invention bears is higher than that of the existing test device, and the water pressure drop in the critical failure state of the test piece and the brittle cracking of the test piece are obvious, which facilitates the analysis of the test results. Observation and recording, its structural characteristics and excellent performance make it very convenient and applicable. The crack-forming member of the invention can well form internal cracks in dry-hard concrete specimens such as roller compacted concrete, and the test results that are closer to the actual engineering conditions can provide more reasonable research on hydraulic splitting of concrete engineering at home and abroad. It has certain theoretical significance and engineering application value.

Description of drawings

Fig. 1 is the structural schematic diagram of the concrete hydraulic splitting test piece of the present invention.

FIG. 2 is a schematic top view cross-sectional view of the concrete hydraulic splitting test piece of the present invention.

FIG. 3 is a schematic cross-sectional front view of the concrete hydraulic splitting test piece of the present invention.

FIG. 4 is an exploded view of the cracked member inside the concrete hydraulic splitting test piece of the present invention.

Detailed ways

In order to fully illustrate the technical solution for realizing the present invention, the present invention will be further described below with reference to specific embodiments.

As shown in Figures 1 to 4, a dry-hard concrete hydraulic splitting test piece of the present invention comprises a mold 1, a compacted dry-hard concrete 2 and a seam-forming member 3. The seam-forming member 3 includes a The seam piece 31, the water inlet pipe 32 and the water outlet pipe 33, the seam-forming member 3 is located at the center position of the upper surface of the dry-hard concrete 2 with half the capacity of the compaction mold, and the VC value of the dry-hard concrete is controlled at 18s. 3. It includes an upper seam sheet 311 and a lower seam sheet 312 with the same structure, the upper seam sheet 311 and the lower seam sheet 312 are aligned up and down, and the upper seam sheet 311 includes an upper sheet body 3111, an upper adhesive The sealing tape 3112 and the upper gasket 3113, the outer edge of the lower surface of the upper body 3111 is surrounded by the upper adhesive sealing tape 3112, the upper gasket 3113 is located on the inner ring of the upper adhesive sealing tape 3112, the upper The upper annular gap between the gasket 3113 and the inner ring of the upper adhesive sealing tape 3112 is 0.5mm to 1mm, preferably the annular gap is 0.8mm, the lower seam sheet 312 includes a lower sheet body 3121, a lower adhesive seal Belt 3122 and lower gasket 3123; the outer edge of the upper surface of the lower body 3121 is adhered to the lower adhesive sealing belt 3122, the lower gasket 3123 is located on the inner ring of the lower adhesive sealing belt 3122, the lower gasket The annular gap between 3123 and the inner ring of the lower adhesive sealing tape 3122 is 0.5mm to 1mm, preferably the lower annular gap is 0.8mm.

The lower surface of the upper adhesive sealing tape 3112 is bonded to the upper surface of the lower adhesive sealing tape 3122, so as to ensure that the upper and lower seamed sheets do not move relative to each other. Before the lower surface of the upper adhesive sealing tape 3112 is bonded to the upper surface of the lower adhesive sealing tape 3122, 8 identical spacers 313 are surrounded between their bonding surfaces, and the spacers are tensile strength. >100kpa, the cumulative length of the spacer accounts for 1/3 of the circumference of the inner edge of the adhesive tape, and the width of the spacer is the same as the distance from the inner edge to the outer edge of the adhesive sealing tape. The function of the spacer is to allow the water in the free-fillable pores between the upper gasket and the lower gasket to flow out through the spacer unhindered, so the water pressure applied through the water inlet pipe can not be blocked. The affected concrete is transmitted to the outside of the jointed piece, which is the key technical point for the success or failure of the concrete hydraulic splitting specimen. When the dry-hard concrete hydraulic splitting specimen is formed, the spacer between the upper and lower adhesive sealing tapes has the function of filtering cement particles. Water can freely enter and exit through the spacer, while cement cannot enter the upper and lower sheets between. During the pressurization test, the water pressure inside the jointed piece can act on the surrounding of the jointed piece in real time and evenly, that is, the leading edge of the internal crack of the dry-hard concrete hydraulic splitting test piece (the leading edge refers to the direction of the crack development direction). The front end, that is, the position of the most edge of the crack, such as a circular crack with a radius of a, the front edge of the crack is on the circumference of the circular crack with a radius of a. Under the action of high water pressure, the crack will open and expand. A circular crack with a larger radius (radius b) is formed, b>a, at this time, the front edge of the crack is on the circumference of the circular crack with radius b, which refers to the sharp corner position of the most edge of the crack section.), more Realistic simulation of the actual hydraulic fracturing process.

The upper and lower sheet bodies 3111 and 3121 are made of plastic material, their tensile strength is greater than 5MPa, and the softness should be 80-100mN, which can adapt to the small deformation of the dry-hard concrete hydraulic splitting test piece during the forming process, and will not Damage occurs during the molding process; the upper and lower gaskets 3113 and 3123 are water-permeable materials, and their thicknesses are adjusted according to the designed crack thickness, which can meet the needs of molding cracks of different thicknesses. The upper gasket 3113 and the lower gasket 3123 have Pores that can be freely filled with water; the outlet end 321 of the water inlet pipe 32 and the inlet end 331 of the water outlet pipe 33 respectively pass through the upper adhesive sealing tape 3112 and the lower adhesive sealing tape 3122 and are arranged opposite to each other, in a shape of 180 The water flow can well discharge the internal air along the internal crack, and the water inlet pipe 32 and the water outlet pipe 33 are made of copper pipes with an outer diameter of 2-3 mm.

Since the air inside the seam-forming member will have a great influence on the test results during the high-pressure hydraulic splitting test, it is necessary to ensure that all the air inside the seam-forming member is discharged during the test, and the outlet end 321 of the water inlet pipe 32 and the water outlet pipe 33 The inlet end 331 of the upper and lower adhesive sealing tapes extends into the annular space of the upper and lower adhesive sealing tapes 3112, 3122 and is 0.25-1.25 mm, preferably 0.5 mm from the inner edge of the upper and lower adhesive sealing tapes. air to fill the cracks with water, the cracks are evenly subjected to water pressure, and the exhaust effect is the best; the water inlet and outlet pipes are L-shaped, and the inlet end of the water inlet pipe and the outlet end of the water outlet pipe Diagonally extending vertically along the inner wall of the mold, the outer wall surfaces of the water inlet pipe 32 and the water outlet pipe 33 are pockmarked surfaces, which can be well bonded to the dry and hard concrete. When the high-pressure water splitting test is performed, the water does not flow along the inlet and outlet. The outer wall of the water outlet pipe flows out, and the inlet and outlet pipes do not move; the water inlet pipe is connected to the pressurized equipment.

The annular gap between the lower gasket 3123 and the inner ring of the lower adhesive sealing tape 3122 is 0.5 mm to 1 mm; the function of the gap between the gasket and the adhesive sealing tape is that after high-pressure water is introduced into the seam-forming member , which is beneficial for the water flow to evenly fill around the gasket, and the pressure to act on the adhesive sealing tape evenly, so that the adhesive sealing tapes at the edges of the two pieces of material are easier to separate freely.

The water inlet and outlet pipes cannot be broken or flattened during the pouring process of the dry hard concrete specimens, so that the water passage cannot be formed.

The slotted sheet may be square. Preferably, the upper and lower sheet bodies are circular, the sealing adhesive tape is circular, the upper and lower gaskets are circular, and the stress on the dry hard concrete is uniform when the circular crack is subjected to high pressure water, The hydraulic fracturing mechanism is analyzed clearly.

Except for the inlet of the inlet pipe and the outlet of the outlet of the water outlet, no other part of the inner seam-forming member composed of the seam-forming sheet and the water inlet and outlet pipes is communicated with the outside world.

The upper and lower adhesive sealing tapes are double-sided tapes.

The upper and lower gaskets are filter paper.

The thickness of the slotted sheet is 1-3 mm.

The width of the upper and lower sealing adhesive tapes should be 1/5 to 1/7 of the size of the seam sheet. If the adhesive sealing tape is too wide, the two sheets cannot be freely separated under the action of internal high-pressure water. If the sealing tape is too narrow, the bonding strength will be insufficient when the dry-hard concrete hydraulic splitting specimen is formed, causing the dislocation of the two pieces of material, and it is very easy to cause the cement slurry to enter the interior of the jointed member and block the internal space of the jointed member. Therefore, the hydraulic splitting test could not be carried out.

The size of the upper and lower sheets is 1/2 to 1/5 of the size of the mold. If the size is too large, it will be interfered by the size effect of the size of the test piece. There is no substantial help for the study of hydraulic fracturing mechanism.

The following describes the implementation method of the dry-hard concrete hydraulic splitting specimen, which mainly includes the following steps:

(1) The steel mold is used as the mold for the hydraulic splitting specimen of the dry-hard concrete. The VC value of the dry-hard concrete is 18s. The dry-hard concrete is formed by tamping technology. The size of the mold can be selected from 150mm×150mm×150mm, 300mm×300mm× 300mm and 450mm×450mm×450mm, the maximum aggregate particle size of the corresponding mold is 40mm, 80mm and 150mm respectively;

(2) First ram the dry hard concrete of half capacity in the compacted mold, put it into the jointed member, place the jointed piece horizontally in the center of the upper surface of the poured concrete, and bend the water inlet pipe and the water outlet pipe 90 degrees from the bottom of the mold respectively. The two diagonal corners are drawn vertically along the inner wall of the mold (for square molds) or respectively from both ends of a diameter line of the mold along the inner wall of the mold (for cylindrical molds), the water inlet of the water inlet pipe and the outlet of the water outlet pipe. The nozzle is higher than the edge of the mold, and the water inlet of the water inlet pipe and the water outlet of the water outlet pipe are sealed to prevent debris from entering;

(3) Then, around the seam sheet, the water inlet pipe and the water outlet pipe, mainly around and above the upper seam sheet, spread a little dry and hard concrete that removes large aggregates to avoid the formation of seams by large aggregates during the tamping process. The damage to the sheet is caused, and the dry hard concrete of the remaining capacity of the mold is laid, and the positions of the two diagonal openings 5 of the square gasket 4 under the tamper plate are respectively corresponding to the water inlet pipe and the water outlet pipe at the two diagonal lead-out positions of the mold ( For square molds) or the two opening positions of the circular gasket under the tamper plate at both ends of the same diameter line correspond to the lead-out positions of the water inlet pipe and the water outlet pipe along the inner wall of the mold at both ends of a certain diameter line of the mold ( For cylindrical molds), the purpose is to prevent the gasket under the tamping plate from contacting the inlet and outlet pipes, so as to protect the inlet and outlet pipes from being damaged during tamping. Water pipe to flexibly control the position of the seam and prevent it from moving;

(4) The mold can be dismantled after standing for 24 hours. Immediately after dismantling the mold, test whether the water inlet and outlet pipes are smooth with water or air. If they are smooth, seal the water inlet and outlet pipes again and transport them to the curing room. , is discarded.

Claims (9)

1. The utility model provides a hard concrete water conservancy splitting test piece which characterized in that: the joint forming member comprises a joint forming sheet, a water inlet pipe and a water outlet pipe, the joint forming member is positioned at the central position of the upper surface of the rammed and compacted dry and compacted concrete with half capacity of the mold, the VC value of the dry and compacted concrete is controlled to be 2-25 s, the joint forming sheet comprises an upper joint forming sheet and a lower joint forming sheet which are identical in structure, the upper joint forming sheet and the lower joint forming sheet are aligned up and down, the upper joint forming sheet comprises an upper sheet body, an upper sealing belt and an upper gasket, the outer edge part of the lower surface of the upper sheet body is adhered with the upper bonding sealing belt in a surrounding manner, the upper gasket is positioned at the inner ring of the upper bonding sealing belt, the lower joint forming sheet comprises a lower sheet body, a lower bonding sealing belt and a lower gasket, the outer edge of the upper surface of the lower sheet body is adhered with the upper surface of the lower bonding sealing belt, the lower surface of the upper bonding sealing belt is adhered with the upper surface of the lower bonding sealing belt, 6-10 identical spacers are arranged between the lower surface of the upper bonding sealing strip and the upper surface bonding surface of the lower bonding sealing strip at intervals, the upper sheet body and the lower sheet body are made of plastic materials, the tensile strength of the upper sheet body and the tensile strength of the lower sheet body are greater than 5MPa, the softness of the upper sheet body and the lower sheet body are 80-100mN, the upper sheet body and the lower sheet body are made of water-permeable materials, a pore capable of being filled with water freely is formed between the upper sheet body and the lower sheet body, the outlet end of the water inlet pipe and the inlet end of the water outlet pipe respectively penetrate through an annular space between the upper bonding sealing strip and the lower bonding sealing strip and are located in an inner ring of the upper bonding sealing strip and an annular space between the upper bonding sealing strip and the lower bonding sealing strip, the inlet end of the water inlet pipe and the outlet end of the water outlet pipe respectively extend out.

2. The dry hard concrete hydraulic fracture test piece according to claim 1, characterized in that: the cumulative length of the spacers accounts for 1/3-1/2 of the perimeter of the inner edge of the adhesive tape, and the width of the spacers is equal to or larger than the distance from the inner edge to the outer edge of the adhesive tape by 1-2 mm.

3. The dry hard concrete hydraulic fracture test piece according to claim 1, characterized in that: the water inlet pipe and the water outlet pipe are L-shaped, the horizontal section of the water inlet pipe and the horizontal section of the water outlet pipe are oppositely arranged at 180-degree intervals, and the distance between the outlet end of the water inlet pipe and the inlet end of the water outlet pipe is 0.25-1.25 mm from the inner ring edge of the upper bonding sealing strip and the lower bonding sealing strip.

4. The dry hard concrete hydraulic fracture test piece according to claim 1 or 2, characterized in that: the upper annular gap between the upper gasket and the inner ring of the upper adhesive sealing band is 0.5mm to 1mm, and the lower annular gap between the lower gasket and the inner ring of the lower adhesive sealing band is 0.5mm to 1 mm.

5. The dry hard concrete hydraulic fracture test piece according to claim 1, characterized in that: the upper sheet body and the lower sheet body are circular, the sealing adhesive tape is circular, and the upper gasket and the lower gasket are circular.

6. The dry hard concrete hydraulic fracture test piece according to claim 1, characterized in that: the upper and lower adhesive sealing tapes are double-sided adhesive tapes, and/or the upper and lower gaskets are filter papers.

7. The dry hard concrete hydraulic fracture test piece according to claim 1, characterized in that: the width of the upper and lower sealing tapes should be 1/5 to 1/7 of the size of the seam piece, and/or 1/2 to 1/5 of the size of the die.

8. The dry hard concrete hydraulic fracture test piece according to claim 1 or 2, characterized in that: the spacer is a filter paper with tensile strength >100kpa and having a filtering effect on cement particles but through which water can freely pass.

9. An implementation method of the dry hard concrete hydraulic fracture test piece according to any one of claims 1 to 8, characterized in that: it comprises the following steps:

(1) a steel mould is used as a mould of the hydraulic fracture test piece of the dry and hard concrete, the VC value of the dry and hard concrete is controlled to be 2-25 s, and the dry and hard concrete is molded by adopting a tamping technology;

(2) firstly, ramming and compacting hard concrete with half capacity in a mould, putting into a seam forming component, horizontally placing seam forming pieces at the central position of the upper surface of the poured concrete, bending a water inlet pipe and a water outlet pipe by 90 degrees, respectively and vertically leading out from two opposite corners of the mould or respectively and vertically leading out from two ends of a certain diameter line of the mould along the inner wall of the mould, wherein a water inlet of the water inlet pipe and a water outlet of the water outlet pipe are higher than the edges of the mould, and sealing the water inlet of the water inlet pipe and the water outlet of the water outlet pipe to prevent sundries from entering;

(3) then spreading a little dry hard concrete for removing the large aggregate around the seam piece, the water inlet pipe and the water outlet pipe, mainly on the periphery and the upper part of the seam piece, avoiding the damage of the large aggregate to the seam piece in the tamping and vibrating process, spreading the dry hard concrete with the residual capacity of the mould, simultaneously respectively corresponding the opening positions of two opposite angles of a square gasket under the tamping plate to the leading-out positions of the water inlet pipe and the water outlet pipe at two opposite angles of the mould or respectively corresponding the opening positions of two circular gaskets under the tamping plate at two ends of the same diameter line to the leading-out positions of the water inlet pipe and the water outlet pipe at two ends of a certain diameter line of the mould along the inner wall of the mould, aiming at preventing the gasket under the tamping plate from contacting with the water inlet pipe and the water outlet pipe, protecting the water inlet pipe and the water outlet pipe from being damaged in the tamping process, manually stabilizing the water inlet pipe and the water outlet pipe during tamping so, the displacement is prevented;

(4) and (3) the test piece can be demoulded after standing for 24 hours, the water or air is used for testing whether the water inlet pipe and the water outlet pipe are unblocked immediately after the mould is demoulded, if the water inlet pipe and the water outlet pipe are unblocked, the water inlet pipe and the water outlet pipe are sealed again and transported to a curing room, and if the water inlet pipe and the water outlet pipe are not unblocked, the water inlet pipe.

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