In-situ lateral pressure and shear composite test device and method

Abstract

The invention discloses an in-situ lateral pressure and shear composite test device and method. The device comprises a lateral pressure device, and the lateral pressure device applies forward pressure stress required by a direct shear test to the side wall of a drill hole; an annular upper transverse plate is fixedly mounted at the upper end of the side pressure device, and a deformation expansion plate is mounted at the lower end; a plurality of symmetrical hoisting lifting rings are arranged on the upper surface of the upper transverse plate, traction force is applied to the hoisting lifting rings through a traction device, and shearing force required by a direct shear test is provided; the deformation expansion plate comprises an annular fixing box, the fixing box is fixedly installed at the lower end of the lateral pressure device, a rotating part is arranged on the fixing box, a plurality of metal blades distributed around a cavity of the lateral pressure device are installed on the end face of the rotating part, and the metal blades are unfolded along with rotation of the rotating part to achieve radial annular cutting and keep an unfolded state after rotation stops. According to the device, vertical and horizontal combined loading of an on-site in-situ direct shear test can be formed, disturbance to an in-situ soil body is small, the effect that one hole has multiple purposes can be achieved, the site and time cost is saved, and the device is suitable for the in-situ strength characteristic test of the soil body.

Description

Technical Field

[0001] The invention belongs to the technical field of soil in-situ testing, and in particular relates to an in-situ lateral pressure and shear composite testing device and method for testing the strength characteristic index of in-situ soil. Background Art

[0002] The in-situ direct shear test is a commonly used in-situ test method in soil mechanics, which is used to determine the in-situ shear strength of soil. However, the traditional in-situ direct shear test method still has limitations in the application of in-situ soil testing. When conducting an in-situ direct shear test, the soil around the target sample needs to be excavated. The overall workload of the test is large, the operation is complicated, and the cost is high. In addition, the excavation process is easy to disturb the in-situ soil and affect the accuracy of the test results. The lateral pressure test is a test method used to study the stress-strain relationship of foundation soil in the horizontal direction. This method inserts a cylindrical lateral pressure gauge vertically into the soil and uses the lateral expansion of the lateral pressure gauge to apply uniform pressure, thereby measuring the relationship between radial pressure and deformation. The lateral pressure test results combined with parameter inversion technology can determine the stress-strain relationship constitutive model parameters that can reflect the in-situ structure of the soil layer, and are widely used in geotechnical engineering tests.

[0003] Due to the limitations of the test methods, the traditional in-situ direct shear test is difficult to be carried out in conjunction with other in-situ tests (such as lateral pressure tests), and the utilization rate of the test site is low. Summary of the invention

[0004] In order to overcome the shortcomings of the above-mentioned prior art, obtain the in-situ parameters of the soil as comprehensively as possible, and improve the site utilization rate of the in-situ test, the present invention is based on the working principle of the lateral pressure tester, uses the lateral pressure device to provide the positive pressure on the side wall of the borehole, proposes an in-situ lateral pressure and shear composite test device, and designs a matching test method to form a vertical and horizontal joint loading for the on-site in-situ direct shear test; the test device is easy to operate, has little disturbance to the in-situ soil, and can achieve the effect of one hole for multiple uses, saving site and time costs, and is suitable for in-situ strength characteristic testing of soil.

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

[0006] An in-situ pressure and shear composite test device comprises a pressure gauge, which applies the normal compressive stress required for a direct shear test to the side wall of a borehole; an annular upper horizontal plate is fixedly installed at the upper end of the pressure gauge, and a deformation expansion plate is installed at the lower end; a plurality of symmetrical lifting rings are provided on the upper surface of the upper horizontal plate, and a traction force is applied to the lifting rings through a traction device to provide the shear force required for the direct shear test; the deformation expansion plate comprises an annular fixed box, which is fixedly installed at the lower end of the pressure gauge and has a rotating part thereon, and a plurality of metal blades distributed around the pressure gauge cavity are installed on the end surface of the rotating part, and the metal blades are expanded with the rotation of the rotating part to realize radial annular cutting, and remain in an expanded state after the rotation stops, and are retracted after the test ends.

[0007] In one embodiment, the upper horizontal plate is a circular metal plate, which is fixedly mounted on the outer wall of the upper end of the pressure transmitter and has no contact with the pressure transmitter cavity.

[0008] In one embodiment, the traction device is connected to the lifting bail, and a tension sensor is provided at the connection.

[0009] In one embodiment, the rotating part is composed of a plurality of vertical fixed tubes, each of which is arranged in a single ring around the pressure relief device cavity. Each fixed tube can rotate around its tube axis driven by a motor in a fixed box. A metal blade is installed at the end of each fixed tube. Each fixed tube has the same rotation speed and rotation direction. The rotation of each fixed tube drives the corresponding metal blade to unfold and cut into the soil.

[0010] In one embodiment, the rotating part is a bearing structure installed between the inner ring of the fixed box and the pressure relief device cavity. A plurality of metal blades are installed at the end of the bearing structure. The bearing structure rotates under the drive of the motor in the fixed box, and each metal blade is unfolded and cuts into the soil as it rotates.

[0011] In one embodiment, the metal blade is arc-shaped, and its arc, width and length are such that it exceeds the outer edge of the fixed box when unfolded, and does not exceed the outer edge of the fixed box when folded.

[0012] In one embodiment, the metal blades are stacked one after another when unfolded to form a ring that extends beyond the outer edge of the fixed box, and the metal blades are stacked one after another when folded to form a ring that does not extend beyond the outer edge of the fixed box and does not contact the fixed tube.

[0013] The present invention also provides a test method based on the in-situ lateral pressure and shear composite test device, which mainly includes the following steps:

[0014] Step 1: Using undisturbed soil as the test soil, dig a test hole in the test soil, and expand the upper part of the test hole to the required depth of the test; the diameter of the expanded hole is slightly larger than the diameter of the upper horizontal plate;

[0015] Step 2: Lift the test device and bury it in the expanded test hole, ensuring that the upper horizontal plate is in full contact with the bottom surface of the expanded hole;

[0016] Step 3, start the motor to drive the metal blades in the retracted state to rotate and expand to cut into the soil; after the metal blades are fully expanded, turn off the motor;

[0017] Step 4: convert the normal compressive stress required for the direct shear test into the lateral pressure value provided by the lateral pressure gauge, use the lateral pressure gauge to pressurize the inner wall of the test hole, and record the relationship curve between the lateral pressure and deformation during the loading process;

[0018] Step 5: Use the traction device to lift the entire test device upward, set the pulling force to the sum of the gravity of the test device and the test soil, and record this state as the initial state of the test. The pulling force at this time is the initial pulling force;

[0019] Step 6: Apply tension to the test device in stages. The magnitude of each stage of tension is controlled according to a fixed ratio of the positive pressure. The tension applied at each stage and the corresponding pull-up height are recorded until a sharp increase in deformation occurs during the pull-up process or the pull-up height reaches a set threshold. The soil is considered to be damaged, and the tension at this time is recorded as the damage tension.

[0020] Step 7, release the pressure in the pressure relief device;

[0021] Step 8: Pull the test device out of the ground, take photos of the soil damage surface, and check whether the unfolding state of the metal blade is normal to determine whether the test is valid;

[0022] Step 9: Remove the soil in the equipment, start the motor, and rotate it in the reverse direction to retract the metal blades; turn off the motor, and the test is over.

[0023] In one embodiment, the diameter of the expanded hole is 10 cm larger than the diameter of the upper transverse plate.

[0024] In one embodiment, the fixed ratio is 10%; the set threshold is: 10% of the distance between the lower end of the upper transverse plate and the upper end of the deformation expansion plate.

[0025] Compared with the prior art, the advantages of the present invention are:

[0026] 1) The in-situ lateral pressure and shear composite test is realized, which has little disturbance to the in-situ soil and high test accuracy.

[0027] 2) It can carry out combined borehole soil pressure test and in-situ direct shear test, achieving the effect of one hole for multiple uses and one set of equipment for multiple tests.

[0028] 3) The test cost is low, the operation is easy, and the control of each system is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the overall structure of the in-situ lateral pressure and shear composite test device of the present invention (with blades folded in).

[0030] Figure 2 It is a schematic diagram of the overall structure of the in-situ lateral pressure and shear composite test device of the present invention (with blades unfolded).

[0031] Figure 3 This is a schematic diagram of the deformed expansion plate structure of the present invention (blades folded in)

[0032] Figure 4 This is a schematic diagram of the deformed expansion plate structure of the present invention (with the blades unfolded)

[0033] Figure 5 It is a schematic diagram of the folding and unfolding of a single blade on a deformable expansion plate of the present invention.

[0034] Figure 6 It is a schematic diagram of the folding of a single blade of the present invention.

[0035] Figure 7 It is a schematic structural diagram of the linkage of the fixed pipes in one embodiment of the present invention.

[0036] Figure 8 yes Figure 7 Schematic diagram of the structure of the single-piece fixed pipe connecting piece.

[0037] Fig. 9 yes Figure 7 Schematic diagram of the connection between two adjacent fixed pipe connecting plates. DETAILED DESCRIPTION

[0038] The embodiments of the present invention are described in detail below with reference to the accompanying drawings and examples.

[0039] In order to carry out in-situ direct shear test and lateral pressure test using the same device and the same borehole, the present invention provides an in-situ lateral pressure and shear composite test device, which improves and upgrades the existing lateral pressure test device so that it can carry out direct shear test on in-situ sand layers on the basis of its original function of completing the lateral pressure test.

[0040] The device of the present invention is deeply buried in the sand layer, and the overall structural diagram of the device is as follows Figure 1 and Figure 2 As shown, from the functional point of view, it includes three major parts: an in-situ soil shear box mechanism, a positive stress loading mechanism and a shear force loading and testing mechanism. From the structural point of view, it mainly includes a pressure relief device 1, an upper cross plate 2, a lifting ring 4, a deformation expansion plate 5, a fixing box 6, a metal blade 8, etc.

[0041] Among them, the upper cross plate 2, the outer wall of the lateral pressure device 1, and the deformation expansion plate 5 are the main components of the in-situ soil shear box mechanism. The in-situ soil shear box mechanism is mainly used to form a thin-walled cylindrical in-situ soil layer to provide a test object for the in-situ direct shear test.

[0042] The pressure gauge 1 and its attached pressurizing device are the main components of the positive stress loading mechanism, which is mainly used to provide the positive compressive stress required for the direct shear test. Specifically, the present invention can apply the positive compressive stress required for the direct shear test to the side wall of the borehole by using the pressure gauge 1 and its attached pressurizing device, which is consistent with the loading process of the pressure gauge test.

[0043] The upper horizontal plate 2, the deformation expansion plate 5, and the traction device and tension sensor acting on the lifting ring 4 are the main components of the shear force loading and testing mechanism. The main function of the shear force loading and testing mechanism is to provide the shear force required for the direct shear test and complete the direct shear test.

[0044] In the present invention, the upper horizontal plate 2 is an annular structure, fixedly mounted on the upper end of the pressure gauge 1. Specifically, it can be a circular metal plate, and is fixedly mounted on the outer wall of the upper end of the pressure gauge by bolts or other fixing methods, and has no contact with the pressure gauge cavity. The number of lifting bail 4 is preferably multiple (two are selected in this embodiment), and is symmetrically arranged on the upper surface of the upper horizontal plate 2 to ensure uniform acceptance. By applying traction force to the lifting bail 4 through a traction device, the shear force required for the direct shear test can be provided. The figure also shows the connecting line interface 3 of the pressure gauge 1, which is used to connect the pressure gauge 1 and its attached loading and measuring device.

[0045] For example, the traction device can be directly connected to the lifting ring 4, and a tension sensor is provided at the connection point (typically such as between the ring and the traction rope). The function of the tension sensor is to monitor the magnitude of the traction force in real time.

[0046] In the present invention, the deformable expansion plate 5 is fixedly mounted on the lower end of the pressure transmitter 1, and is also not in contact with the pressure transmitter cavity. It mainly includes an annular fixed box 6, which is fixedly mounted on the lower end of the pressure transmitter 1. Its cross section is preferably annular, and the interior is used to install a motor. A rotating part is also installed on the fixed box 6, and a plurality of metal blades 8 are installed on the end face of the rotating part. Each metal blade 8 is evenly distributed in a single circle around the pressure transmitter cavity. The rotating part is driven to rotate by the motor inside the fixed box 6, and each metal blade 8 can be expanded with the rotation of the rotating part to achieve radial annular cutting (such as Figure 2 and Figure 4 As shown in the figure, a thin-walled cylindrical in-situ soil structure to be sheared is formed by radial annular cutting, and the structure is kept in an expanded state after the rotation stops, and is retracted after the test is completed (as shown in the figure). Figure 1 and Figure 3As shown in FIG. 1 , the diameter of the side pressure device in the folded state is close to that of the side pressure device, and can be folded by inverting. The end face here refers to the upper end face or the lower end face, and the upper end face is used in the embodiment of the present invention.

[0047] According to the above structure, through the above three aspects of the structural system, the shear strength test of the original sand layer inside the borehole can be achieved.

[0048] The metal blades 8 of the present invention can be expanded and retracted in various forms, and two feasible solutions are provided in the embodiments of the present invention.

[0049] In the first scheme, the rotating part is composed of a plurality of vertical fixed tubes 7, each of which is arranged in a single ring around the pressure relief chamber and can be inserted into the fixed box 6 for installation, and has a certain radial distance from the pressure relief chamber and the outer edge of the fixed box 6. The end of each fixed tube 7 (the upper end in this embodiment) extends a certain distance from the end face of the fixed box 6 and is installed with a metal blade 8. Each fixed tube 7 can rotate around its own tube axis driven by the motor in the fixed box 6. Each fixed tube 7 has the same rotation speed and rotation direction. The rotation of each fixed tube 7 drives each corresponding metal blade 8 to expand and cut into the soil.

[0050] In the second scheme, the rotating part is a bearing structure installed between the inner ring of the fixed box 6 and the pressure relief device cavity. The end of the bearing structure (the upper end in this embodiment) extends out of the fixed box 6 for a certain distance and is installed with multiple metal blades 8. The bearing structure rotates under the drive of the motor in the fixed box 6, and each metal blade 8 is unfolded and cut into the soil as it rotates.

[0051] In the above scheme, the metal blades 8 are arc-shaped, and their arc, width and length are such that they extend beyond the outer edge of the fixed box 6 when unfolded, and do not extend beyond the outer edge of the fixed box 6 when folded. When unfolded, the metal blades 8 are sequentially overlapped to form a ring that extends beyond the outer edge of the fixed box 6, and when folded, the metal blades 8 are sequentially overlapped to form a ring that does not extend beyond the outer edge of the fixed box 6, and do not collide or contact with the fixed tube 7, such as Figure 5 and Figure 6 As shown. The material stiffness of the metal blade 8 should be much greater than the soil stiffness to ensure that the metal blade will not be significantly deformed during loading. Steel can be selected. In solution 1, the fixed pipe 7 and the metal blade 8 can be an integrated structure.

[0052] The specific installation method of the metal blade 8 and the fixed tube 7 or the bearing structure is the existing technology, and reference can be made to the folding / expanding fan blades in the existing technology, such as patents CN206860502U, CN211666918U, CN204646788U, CN209261876U, etc., all of which can realize the blade expansion / contraction function of the present invention.

[0053] In one embodiment of the present invention, reference Figure 7 , Figure 8 and Fig. 9 As shown, Figure 7 The internal form of the deformed expansion plate 5 is shown. A fixed pipe connecting plate 9 is arranged around the fixed pipes 7 arranged in a ring. The structure of the single-piece fixed pipe connecting plate 9 is as follows: Figure 8 As shown, the arc-shaped plate has two ends extending toward the center of the ring, and connection holes are provided at both ends. The middle connection part of the arc-shaped plate can be a broken line type, that is, Figure 8 The portion shown is close to the center of the ring, while the other portion is far from the center of the ring, forming an asymmetric shape. Two adjacent fixed pipe connecting plates 9 are connected by a support rod passing through the connecting holes at the adjacent ends, such as Fig. 9 As shown. The support rod is parallel to the length direction of the fixed tube 7 and has a connection relationship. Therefore, when the fixed tube 7 rotates, it can drive the support rod to rotate, and at the same time drive the corresponding fixed tube connecting plate 9 to move, and finally realize linkage to ensure that each metal blade 8 moves neatly. It is worth noting that in the present invention, the fixed tube 7 only needs to rotate a certain angle, and does not need to rotate a large angle or even 360°. For example, the metal blade 8 is fixedly installed at one end of the fixed tube 7. When the fixed tube 7 is reset, that is, the rotation angle is 0, each metal blade 8 is in its first position, that is, the retracted position, as shown in FIG. Figure 3 When the fixing tube 7 is reset, that is, the rotation angle is α (such as 15-45°), each metal blade 8 is located in its second position, that is, the unfolded position, as shown in FIG. Figure 4 , Figure 5 As shown, the fixed tube 7 can be fixed at this moment, that is, each metal blade 8 is fixed at its unfolded position. Thereafter, when reversing α, the fixed tube 7 is reset, and each metal blade 8 is located at its first position, that is, the folded position.

[0054] The specific steps of using the device of the present invention to carry out the in-situ lateral pressure and shear composite test are as follows:

[0055] Step 1: Use undisturbed soil as the test soil, use drilling equipment to dig a test hole in the test soil, expand the upper part of the test hole, dig to the required depth for the test, and remove the remaining soil at the bottom of the expanded hole. The expanded hole diameter should be slightly larger than the diameter of the upper cross plate 2, but not too large, so as not to reduce the overburden stress of the surrounding soil, resulting in a smaller test result. For example, 10 cm larger is sufficient. The selection of the test depth area must not overlap with the area of ​​the lateral pressure test that has been carried out, and it is necessary to ensure that the test soil is undisturbed soil.

[0056] 2. Connect the device to the lifting equipment through the lifting ring 2, lift the test device, and bury it in the expanded test hole to ensure that the upper horizontal plate 2 of the device is in full contact with the bottom surface of the expanded hole.

[0057] 3. Start the motor to make the metal blade 8 in the folded state rotate counterclockwise and expand to cut into the soil (see Figure 5 ). After each metal blade 8 is fully unfolded, the motor is turned off.

[0058] 4. Convert the direct shear normal stress required for the direct shear test into the lateral pressure value provided by the lateral pressure gauge 1, use the lateral pressure gauge 1 to pressurize the inner wall of the test hole, and record the relationship curve between the lateral pressure and deformation during the loading process.

[0059] 5. Use the traction device to lift the test device upward as a whole, set the tension to the sum of the gravity of the test device and the test soil, and record this state as the initial state of the test. The tension at this time is the initial tension.

[0060] 6. Apply tension to the test device in stages. The magnitude of each stage of tension is controlled according to a fixed proportion of the positive pressure (typically 10%). Record the tension applied at each stage and the corresponding pulling height. When the deformation increases sharply during the pulling process or the pulling height reaches a set threshold (typically 10% of the distance between the lower end of the upper cross plate 2 and the upper end of the deformation expansion plate 5), the soil is considered to be damaged and the tension at this time is recorded as the damaging tension.

[0061] 7. Release the pressure in the pressure relief device 1.

[0062] 8. Pull the test device out of the ground, take photos of the soil failure surface (i.e., the interface between the soil sheared out with the test device and the soil on the side wall of the test hole after the test), and check to confirm whether the unfolding state of the metal blade 8 is normal, so as to determine whether this test is valid.

[0063] 9. Remove the soil in the equipment (i.e. the soil between the upper horizontal plate 2, the outer wall of the lateral pressure device, and the deformation expansion plate 5, which is sheared and pulled out with the test device), start the motor, and make the blades rotate clockwise and retract into the deformation expansion plate. Turn off the motor, and the test is over.

Claims

1. An in-situ lateral pressure and shear composite test device, characterized in that: The invention comprises a pressure gauge (1), wherein the pressure gauge (1) applies the positive compressive stress required for the direct shear test to the side wall of the borehole; an annular upper horizontal plate (2) is fixedly installed at the upper end of the pressure gauge (1), and a deformation expansion plate (5) is installed at the lower end; a plurality of symmetrical lifting rings (4) are arranged on the upper surface of the upper horizontal plate (2), and a traction force is applied to the lifting rings (4) through a traction device to provide the shear force required for the direct shear test; the deformation expansion plate (5) comprises an annular fixed box (6), wherein the fixed box (6) is fixedly installed at the lower end of the pressure gauge (1), and a rotating part is arranged on the fixed box; a plurality of metal blades (8) distributed around the pressure gauge cavity are installed on the end surface of the rotating part; the metal blades (8) are expanded with the rotation of the rotating part to realize radial annular cutting, and remain in the expanded state after the rotation stops, and are retracted after the test ends.

2. The in-situ lateral pressure and shear composite test device according to claim 1, characterized in that: The upper horizontal plate (2) is a circular metal plate, which is fixedly mounted on the outer wall of the upper end of the pressure relief device and has no contact with the pressure relief device cavity.

3. The in-situ lateral pressure and shear composite test device according to claim 1 or 2, characterized in that: The traction device is connected to the lifting bail (4), and a tension sensor is arranged at the connection point.

4. The in-situ lateral pressure and shear composite test device according to claim 1, characterized in that: The rotating part is composed of a plurality of vertical fixed tubes (7), each of which is arranged in a single ring around the pressure relief chamber. Each fixed tube (7) can rotate around its tube axis under the drive of a motor in a fixed box (6). A metal blade (8) is installed at the end of each fixed tube (7). Each fixed tube (7) has the same rotation speed and rotation direction. The rotation of each fixed tube (7) drives each corresponding metal blade (8) to expand and cut into the soil.

5. The in-situ lateral pressure and shear composite test device according to claim 1, characterized in that: The rotating part is a bearing structure installed between the inner ring of the fixed box (6) and the pressure relief device cavity. A plurality of metal blades (8) are installed at the end of the bearing structure. The bearing structure rotates under the drive of the motor in the fixed box (6), and each metal blade (8) is unfolded and cuts into the soil as it rotates.

6. The in-situ lateral pressure and shear composite test device according to claim 4 or 5, characterized in that: The metal blade (8) is arc-shaped, and its arc, width and length are such that it exceeds the outer edge of the fixed box (6) when unfolded, and does not exceed the outer edge of the fixed box (6) when folded.

7. The in-situ lateral pressure and shear composite test device according to claim 6, characterized in that: When unfolded, the metal blades (8) are stacked one after another to form a ring that extends beyond the outer edge of the fixed box (6); when folded, the metal blades (8) are stacked one after another to form a ring that does not extend beyond the outer edge of the fixed box (6) and does not contact the fixed tube (7).

8. The test method based on the in-situ lateral pressure and shear composite test device of claim 1 is characterized in that: The steps include: Step 1: using undisturbed soil as the test soil, digging a test hole in the test soil, and expanding the upper part of the test hole to a depth required for the test; the diameter of the expanded hole is slightly larger than the diameter of the upper horizontal plate (2); Step 2, hoist the test device and bury it in the expanded test hole, ensuring that the upper horizontal plate (2) is in full contact with the bottom surface of the expanded hole; Step 3, starting the motor to drive the metal blade (8) in the retracted state to rotate and expand to cut into the soil; after the metal blade (8) is fully expanded, turning off the motor; Step 4, converting the normal compressive stress required for the direct shear test into the lateral pressure value provided by the lateral pressure gauge, using the lateral pressure gauge (1) to pressurize the inner wall of the test hole, and recording the relationship curve between the lateral pressure and the deformation during the loading process; Step 5: Use the traction device to lift the entire test device upward, set the pulling force to the sum of the gravity of the test device and the test soil, and record this state as the initial state of the test. The pulling force at this time is the initial pulling force; Step 6: Apply tension to the test device in stages. The magnitude of each stage of tension is controlled according to a fixed ratio of the positive pressure. The tension applied at each stage and the corresponding pull-up height are recorded until a sharp increase in deformation occurs during the pull-up process or the pull-up height reaches a set threshold. The soil is considered to be damaged, and the tension at this time is recorded as the damage tension. Step 7, releasing the pressure in the pressure relief device (1); Step 8: Pull the test device out of the ground, take photos of the soil damage surface, and check whether the unfolded state of the metal blade (8) is normal, so as to determine whether the test is effective; Step 9: Remove the soil in the equipment, start the motor, and rotate it in the reverse direction to retract the metal blades (8); turn off the motor, and the test is finished.

9. The test method according to claim 1, characterized in that: The diameter of the expanded hole is 10 cm larger than the diameter of the upper horizontal plate (2).

10. The test method according to claim 1, characterized in that: The fixed ratio is 10%; the set threshold is: 10% of the distance between the lower end of the upper horizontal plate (2) and the upper end of the deformation expansion plate (5).

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