CN103471796B - Tunnel Cast-in-place concrete lining anti-seismic performance test methods - Google Patents

Abstract

The invention discloses a method for testing the seismic performance of the cast-in-place concrete lining of a tunnel, which is characterized in that it comprises the following steps: ① making a partial test piece of the cast-in-place concrete lining; ② installing the partial test piece of the cast-in-place concrete lining in a special test piece loading box Middle; ③ Apply static load to the specimen loading box through the static loading system; ④ Install the above experimental device on the vertical electro-hydraulic servo-driven seismic simulation shaking table to input the vibration load; ⑤ Unload the vibration load and static load successively , record and analyze the damage of the specimen, so as to evaluate its seismic performance. The present invention simulates the actual stress state of the cast-in-place concrete lining through a special loading mechanism, and combines the existing earthquake simulation shaking table to test the seismic performance of its partial specimens, which can better reflect circular or quasi-circular tunnels Seismic properties of cast-in-place concrete lining structures as a whole. The invention adopts the partial test piece of cast-in-situ concrete lining to carry out the test, which greatly saves the test cost compared with the full-section test.

Description

Test method for seismic performance of cast-in-situ concrete lining in tunnels

technical field

The invention relates to the research on the anti-seismic performance of the tunnel support structure, in particular to a method for testing the anti-seismic performance of the cast-in-place concrete lining of the tunnel.

Background technique

With the implementation of the western development strategy, a large number of tunnel projects under construction of roads, railways and hydropower will be built near active faults and high-intensity earthquake areas. For example, there are tens of thousands of railway tunnels in my country, of which nearly a thousand are located in strong earthquake areas, and their seismic safety is a matter of great concern to engineering designers.

In order to reduce disasters caused by earthquakes, the seismic performance of support structures should be fully considered in tunnel support design. Cast-in-place concrete lining, as a commonly used support structure in underground engineering, often suffers from spalling, cracks and collapse damage under the influence of earthquake loads. In order to prevent these accidents, it is necessary to conduct reasonable tests on the seismic performance of cast-in-place concrete linings.

Since the vibration load cannot be artificially applied under field conditions, its seismic performance cannot be tested on site; through laboratory model tests, the similarity ratio is difficult to determine, and the size effect is very obvious, so it cannot be used as a method for testing seismic performance; In the case of prototype testing, the cost is high, and it also faces the disadvantages that the boundary conditions are difficult to meet and the vibration load is difficult to apply.

A reasonable test method must firstly be able to reflect the structural characteristics of the arc-shaped shell of the cast-in-place concrete lining; secondly, it should be able to make its stress state the same or similar to the site conditions, that is, under the pressure of the surrounding rock, the lining can reach a state of high stress. And keep it for a certain period of time, and apply the shock load after the deformation is stable, so as to study the impact of earthquake on the tunnel lining. Due to the limitations of various conditions, there is no experimental method that can meet the above requirements, so it is difficult to directly test the seismic performance of cast-in-place concrete lining.

Contents of the invention

The purpose of the present invention is to provide a method for testing the anti-seismic performance of the cast-in-place concrete lining of the tunnel in order to overcome the deficiencies of the prior art.

Its technical solutions are:

A method for testing the anti-seismic performance of a tunnel cast-in-place concrete lining, characterized in that it comprises the following steps:

Make a partial test piece of cast-in-place concrete lining, and apply lubricating material on its side to reduce the friction force received during the experiment; the upper and lower surfaces of the partial test piece of cast-in-place concrete lining are coaxial arc surfaces, The extension line of the side passes through the axis of the above-mentioned arc surface, and the front and rear sides are perpendicular to the horizontal plane; in essence, it is a trapezoidal test block formed by cutting the tunnel cast-in-place concrete lining through the two faces of the tunnel axis; the partial test piece of the cast-in-place concrete lining The specific production methods include the following two methods: a. Make molds of corresponding shapes, bind steel bars and pour concrete in imitation of on-site construction conditions, demould after curing for a certain period of time under similar on-site conditions, and then polish the surface smooth; b. Cut the test piece with a rough shape at the tunnel construction site, process it into a standard shape with a stone grinder and other tools, and polish it smooth;

Install the partial specimen of the cast-in-place concrete lining into the specimen loading box; the specimen loading box includes a U-shaped groove, a triangular prism pad, a loading pad and a side baffle; the U-shaped groove is an integral structure, including a bottom plate and two side walls; the two right-angled surfaces of the triangular prism block are respectively in contact with the bottom plate and the inner surface of the side wall of the U-shaped groove, and the inclination angle of the inclination matches the inclination angle of the two inclination angles of the local specimens of the poured concrete lining; the lower surface of the loading block is The circular arc is in contact with the upper surface of the local cast-in-place concrete lining, and there is a gap between the left and right sides of the loading pad and the slope of the triangular prism pad to prevent the two from being squeezed during the loading process; the side baffle is fixed in the U-shaped groove The front and rear sides of the inner surface are in contact with the front and rear surfaces of the cast-in-place concrete lining partial test piece, the function is to prevent the axial deformation of the cast-in-place concrete lining partial test piece, so as to meet the requirements of the plane strain state;

Static loading is applied to the test piece loading box through the static loading system, so that the test piece reaches the required stress state, so as to simulate the effect of surrounding rock pressure on the cast-in-place concrete lining; the static loading system includes a base, a jack, and a reaction force Backing plate, reaction steel bar and support guide rail, the jack is used to apply static load, the left and right sides of the reaction backing plate are respectively provided with through holes for connecting the reaction steel bar, one end of the reaction bar is fixed on the base, and the other end is fixed on the counter force pad; the support guide rail is fixed on the base, and its function is to hold the specimen loading box before the experiment and prevent it from deflecting during the experiment;

Install the above-mentioned experimental device on a vertical electro-hydraulic servo-driven seismic simulation vibration table, input the vibration load of specified frequency, amplitude and waveform; through stress and deformation measurement units, such as stress sensors and strain sensors, etc., measure the Stress and deformation during the experiment to analyze its dynamic response characteristics;

The vibration load and the static load are successively removed, the specimen loading box is removed and the specimen is taken out, and the damage of the specimen is recorded and analyzed, so as to evaluate its seismic performance.

Principle of the present invention is:

At present, most of the tunnels under construction adopt circular or quasi-circular cross-sections; when the difference between the horizontal pressure and vertical pressure of the surrounding rock is not large, the stress, deformation and failure of the tunnel cast-in-place concrete lining can be approximately regarded as axial For symmetry problems, a part of it can be tested to reflect the overall properties of the cast-in-place concrete lining.

The present invention uses a special test piece loading box and a static loading system, combines the existing earthquake simulation shaking table, and considers the arc-shaped shell structure characteristics of the circular or quasi-circular tunnel cast-in-place concrete lining. The seismic performance test of local specimens can better reflect the seismic characteristics of the overall structure.

Description of drawings

Below in conjunction with accompanying drawing and specific embodiment the present invention will be further described:

Fig. 1 is a mechanical schematic diagram of the present invention;

Fig. 2 is a schematic diagram of the main structure of the present invention.

detailed description

In conjunction with accompanying drawing 1, the basis of the present invention is that a large part of the tunnels currently under construction adopt circular or quasi-circular cross-sections. Under the condition that the horizontal pressure and vertical pressure of the surrounding rock are not much different, the impact of the tunnel cast-in-place concrete lining The problems of force, deformation and failure can be approximately regarded as axisymmetric problems, and a part of them can be tested to reflect the overall properties of the cast-in-place concrete lining.

In conjunction with accompanying drawing 2, a kind of tunnel cast-in-place concrete lining seismic performance testing method is characterized in that comprising the following steps:

Make the cast-in-place concrete lining partial test piece 1, and apply lubricating material on its side, to reduce the frictional force received in its experiment process; Described cast-in-place concrete lining partial test piece, the upper and lower surfaces are coaxial arc surfaces, The extension lines of the left and right sides pass through the axis of the above-mentioned arc surface, and the front and rear sides are perpendicular to the horizontal plane; in essence, it is a trapezoidal test block formed by cutting the cast-in-place concrete lining of the tunnel through the two faces of the tunnel axis; the partial test piece of the cast-in-place concrete lining The specific production methods include the following two: a. Make molds of corresponding shapes, bind steel bars and pour concrete according to the site construction conditions, demould after curing for a certain period of time under similar site conditions, and then polish the surface smooth; b. Cut the test piece with a rough shape at the tunnel construction site, process it into a standard shape with a stone grinder and other tools, and polish it smoothly.

Install the cast-in-situ concrete lining partial test piece 1 in the test piece loading box; the test piece loading box includes a U-shaped groove 2, a triangular prism pad 3, a loading pad 4 and side baffles; the U-shaped groove 2 is The overall structure includes the bottom plate and two side walls; the two right-angled surfaces of the triangular prism block 3 are respectively in contact with the bottom plate and the inner surface of the side wall of the U-shaped groove 2, and the inclination angle of the inclination is the same as that of the two inclination angles of the local test piece 1 of the poured concrete lining. Matching; the lower surface of the loading pad 4 is arc-shaped and in contact with the upper surface of the cast-in-place concrete lining partial test piece 1, and there is a gap between the left and right sides of the loading pad 4 and the slope of the triangular prism pad 3 to prevent both Extrusion occurs; the side baffles are fixed on the front and rear sides of the U-shaped groove, and their inner surfaces are in contact with the front and rear surfaces of the local cast-in-place concrete lining specimens. Requirements for the plane strain state.

Static loading is applied to the test piece loading box by the static loading system, so that the test piece reaches the required stress state, so as to simulate the effect of the surrounding rock pressure on the cast-in-place concrete lining; the static loading system includes a base 5, a jack 6, Reaction force backing plate 7, reaction force reinforcing bar 8 and support guide rail 9, jack 6 are used for applying static load, and the left and right sides of reaction force backing plate 7 are respectively provided with through holes for connecting reaction force reinforcing bar 8, and one end of reaction force reinforcing bar 8 is fixed On the base 5, the other end is fixed on the reaction backing plate 7; the support guide rail 9 is fixed on the base, and its function is to hold the specimen loading box before the experiment and prevent it from deflecting during the experiment.

The above-mentioned experimental device is installed on the vertical electro-hydraulic servo-driven earthquake simulation shaking table 10, and the vibration load of the specified frequency, amplitude and waveform is input; the test piece is measured through stress and deformation measurement units, such as stress sensors and strain sensors. Stress and deformation during the experiment to analyze its dynamic response characteristics.

The vibration load and the static load are successively removed, the specimen loading box is removed and the specimen is taken out, and the damage of the specimen is recorded and analyzed, so as to evaluate its seismic performance.

The above-described embodiments are only one of the more preferred specific implementation modes of the present invention, and the usual changes and replacements performed by those skilled in the art within the scope of the technical solutions of the present invention shall be included in the protection scope of the present invention.

Claims (1)

1. A tunnel cast-in-place concrete lining seismic performance testing method, is characterized in that, comprises the following steps: The first step: make a partial test piece of cast-in-place concrete lining, and apply lubricating material on its side to reduce the friction force received during the experiment; the upper and lower surfaces of the partial test piece of cast-in-place concrete lining are coaxial circles The extension lines of the arc surface and the left and right sides pass through the axis of the above arc surface, and the front and rear sides are perpendicular to the horizontal plane; the specific production methods of the local cast-in-place concrete lining test pieces include the following two: a. Make molds of corresponding shapes, imitating the construction conditions on site Bind steel bars and pour concrete, demould after curing for a certain period of time under similar on-site conditions, and then polish the surface smooth; b. Cut a roughly shaped test piece at the tunnel construction site with a cutting machine, and process it into a standard shape and polished smooth; Step 2: install the local cast-in-place concrete lining test piece into the test piece loading box; the test piece loading box includes a U-shaped groove, a triangular prism pad, a loading pad and a side baffle; the U-shaped groove is a whole The structure includes the bottom plate and two side walls; the two right-angled surfaces of the triangular prism block are respectively in contact with the bottom plate and the inner surface of the side wall of the U-shaped groove, and the inclination angle of the inclination matches the inclination angle of the two inclination angles of the partial specimen of the cast-in-place concrete lining; The lower surface of the pad is arc-shaped, and there is a gap between the left and right sides of the loading pad and the slope of the triangular prism pad; the side baffles are fixed on the front and rear sides of the U-shaped groove; Step 3: apply a static load to the specimen loading box through the static loading system, so that the specimen reaches the required stress state, to simulate the effect of the surrounding rock pressure on the local specimen of the cast-in-place concrete lining; the static loading system Including base, jack, reaction pad, reaction reinforcement and support guide rail; Step 4: Install the above-mentioned specimen loading box and static loading system on the vertical electro-hydraulic servo-driven seismic simulation vibration table, and input the vibration load with specified frequency, amplitude and waveform; through the stress and deformation measurement unit, such as Stress sensor and strain sensor measure the stress and deformation of the specimen during the experiment to analyze its dynamic response characteristics; Step 5: Remove the vibration load and static load successively, remove the specimen loading box and take out the specimen, record and analyze the damage of the specimen, so as to evaluate its seismic performance.