A post-construction ultrasonic testing method for foamed concrete on the back of high fill platforms

Abstract

The present invention discloses a method for ultrasonic detection of foamed concrete after construction of a high fill platform. First, the laying position of the reinforced layer of the high fill platform is clarified, and then the drilling position is selected according to the set ratio. The incident angle range is determined according to the position relationship of the reinforced layer, and the detection hole is drilled avoiding the reinforced layer and the acoustic detection tube is buried for ultrasonic detection. The appropriate detection spacing is selected according to the ultrasonic detection result. The present invention uses ultrasonic detection to detect the quality of foamed concrete after construction of the high fill platform without destroying the surface structure of the road surface. The actual on-site operation method is simple and does not affect the normal use of the road. It is also suitable for quality detection of fillers of other high fill structures.

Description

Technical Field

[0001] The invention belongs to the technical field of civil engineering quality detection, and more specifically relates to a post-construction ultrasonic detection method for foamed concrete on the back of a high-fill platform. Background Art

[0002] The back of the abutment refers to a section of the connecting roadbed that connects the main roadbed on one or both sides of the abutment or culvert. The connecting roadbed has higher requirements than the main roadbed, and its compaction degree reaches 96% or more. The filling material of the connecting roadbed needs to use gravel soil or sandy soil with good permeability. Compared with the traditional back of the abutment, the high-fill foam concrete back of the abutment is filled with high-performance lightweight foam concrete, and one or more reinforcement layers are usually provided in the lower layer of the roadbed. Foam concrete, also known as foamed cement, is a lightweight, heat-insulating, heat-insulating, fire-resistant, sound-insulating and frost-resistant concrete material. It is used in embankment filling and has the advantages of effectively reducing soil load, reducing roadbed settlement deformation and solving the problem of bridgehead jumping. The traditional detection method requires pre-burying detection pipes or drilling holes on the surface of the roadbed before roadbed construction, but this method cannot be applied to the detection of high-fill abutment foam concrete that has been completed and put into normal use. A nondestructive testing method for bubble-mixed lightweight soil embankment with publication number CN107870201A is a method of applying ultrasonic testing to the quality testing of bubble-mixed lightweight soil roadbed, but it is also unable to test the roadbed that has been completed and opened to traffic. Summary of the invention

[0003] The present invention aims to avoid the deficiencies of the above-mentioned prior art and provide a post-construction ultrasonic detection method for foamed concrete on the back of a high fill platform, so as to achieve normal detection of the roadbed on the back of a high fill platform in operation and reduce damage to the roadbed.

[0004] The post-construction ultrasonic detection method for foamed concrete on the back of a high-fill platform of the present invention is characterized in that: one side surface of the back of the platform is used as a detection surface, and each detection opening is distributed in a rectangular array on the detection surface, in the rectangular array, i represents the row number where the detection opening is located, and j represents the column where the detection opening is located; i=1,2,...N; j=1,2,...N; the opening center point of the detection hole is used as the incident point A, and the bottom center point of the detection hole is used as the end point B, and a hole is drilled from the incident point A along the direction of the AB line toward the back of the platform to form a detection hole with an incident angle of α and a depth of D; an acoustic detection tube is buried in the detection hole, and ultrasonic detection is performed using the acoustic detection tube to obtain ultrasonic detection data of the back of the platform, thereby realizing post-construction ultrasonic detection of foamed concrete on the back of the high-fill platform.

[0005] The post-construction ultrasonic detection method for foamed concrete of high fill platform back of the present invention is also characterized in that: a three-dimensional rectangular coordinate system is established for the high fill platform back, with the longitudinal direction of the roadbed as the x-axis, the transverse direction of the roadbed as the z-axis, and the vertical direction as the y-axis;

[0006] Set the center distance between two adjacent detection holes in the same row, that is, the row spacing L h for:

[0007]

[0008] Set the center distance between two adjacent detection holes in the same row, that is, the row spacing L v for:

[0009]

[0010] in:

[0011] L h It is the center row distance between two adjacent detection holes;

[0012] L v is the center row distance between two adjacent detection holes;

[0013] [·] indicates rounding operation; m is the number of pouring layers of the platform back;

[0014] h is the height of the table back, b is the width of the table back, and the section coefficient a is 1.1;

[0015] α is the incident angle, which refers to the angle between the axis of the detection hole and the z axis. The axis of the detection hole is in the zoy plane and tilts downward from one end of the hole mouth of the detection hole.

[0016] The post-construction ultrasonic detection method for foamed concrete on the back of a high-fill platform of the present invention is also characterized in that the coordinates of the center points of the detection holes in the i-th row and j-th column in the rectangular array in the three-dimensional rectangular coordinate system are marked as (x ij ,y ij ,z ij ); then the coordinate matrix formed by the center point coordinates of each detection orifice in the rectangular array is:

[0017]

[0018] in:

[0019] t is the thickness of the protective layer of the reinforcement layer, which is used to protect the steel bars and refers to the distance from the outermost steel bars to the surface of the foam concrete;

[0020] T is the protection distance of the detection hole drilling, T = t + 5.5l, l is the spacing of the steel bars in the reinforcement layer;

[0021] D0 is the thickness of the road base filling material at the top of the abutment; D1 is the thickness of the road base filling material from the reinforcement layer to the bottom of the road base filling material at the top of the abutment.

[0022] The ultrasonic detection method for high fill platform foam concrete after construction of the present invention is also characterized by:

[0023] If there is only one reinforced layer, the incident angle α is determined as follows:

[0024] The coordinates of the incident point A, i.e. the incident point coordinates, are marked as: (T, D0+D1-2t, 0)

[0025] The coordinates of the intersection of the AB line and the reinforced layer are marked as: (T, D0+D1, t+0.5pl)

[0026] p is the set of odd numbers in the natural number set;

[0027] Then the incident angle α is:

[0028] Thus, the function family of the incident angle α is obtained, and the detection hole is drilled at the incident angle α so that the detection hole is located at the center of the adjacent steel bars;

[0029] According to the detection hole diameter d k and the diameter of the reinforcement layer steel bar d s The safe fluctuation range β of the function family of the incident angle α is set to:

[0030]

[0031] in:

[0032]

[0033] And set the lower limit of the incident angle α minα to:

[0034] The post-construction ultrasonic detection method for foamed concrete on the back of a high-fill platform of the present invention is also characterized in that: the reinforced layer is two layers, namely the upper reinforced layer and the lower reinforced layer; the method of obtaining the function family of the incident angle α and the safe fluctuation range β for the reinforced layer as one layer is applied to the upper reinforced layer and the lower reinforced layer respectively;

[0035] For the lower reinforcement layer, the coordinates of the intersection of the AB line and the lower reinforcement layer are marked as: (T, D0+D1+D2, )

[0036] D1 is the thickness of the reinforcement layer, i.e. the upper reinforcement layer to the bottom of the roadbed filler at the top of the abutment;

[0037] D2 is the distance between two reinforcement layers;

[0038] Use exhaustive method to confirm through verification is in the interval , it indicates that the incident angle α meets the requirements.

[0039] The ultrasonic detection method for post-construction foam concrete of the high fill platform back of the present invention is also characterized in that the depth D of the detection hole is set to:

[0040]

[0041] The post-construction ultrasonic detection method for foamed concrete on the back of a high-fill platform of the present invention is also characterized in that pulley blocks are arranged at intervals along the axial direction of the detection hole on the inner side wall of the detection hole so that the acoustic detection tube is located at the center of the detection hole.

[0042] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0043] 1. The method of the present invention does not damage the roadbed surface, does not affect normal operation, and does not damage the reinforced layer, and can be effectively applied to post-construction detection of foamed concrete on the back of high fill platforms.

[0044] 2. The present invention adopts ultrasonic detection technology, the equipment is easy to carry, the equipment price is low, and the detection is convenient and fast.

[0045] 3. There is a certain correlation between the wave velocity of ultrasound in concrete and its strength. The concrete strength can be estimated by establishing a "strength-wave velocity" curve. The foam concrete involved in the present invention is a mixture of foam and cement slurry. There are fewer factors that affect ultrasonic detection, and the detection result is more reliable.

[0046] 4. The sonic detection tube in the present invention is used to ensure that the sonic detection tube is located at the center of the detection hole, thereby ensuring detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a schematic diagram of the vertical roadbed side coordinates of the high fill platform back in the present invention;

[0048] Figure 2 It is a schematic diagram of the single-layer reinforcement layer and the detection hole arrangement of the high fill platform back in the present invention;

[0049] Figure 3 This is a schematic diagram of the double-layer reinforced layer on the back of the high fill platform in the present invention;

[0050] Figure 4 It is a schematic diagram of the structure of the acoustic detection tube of the present invention.

[0051] Numbers in the figure: 1 roadbed side, 2 reinforcement layer, 3 detection hole, 4 acoustic detection pipe, 5 PVC pipe, 6 pulley. DETAILED DESCRIPTION

[0052] See also Figure 1 and Figure 2 In this embodiment, the abutment refers to a section of connecting roadbed that connects the abutment or culvert with the main roadbed. The high fill abutment is made of lightweight foamed concrete, which has one or more reinforcement layers 2. The reinforcement layer 2 is a mesh structure formed by binding steel bars and is parallel to the roadbed surface.

[0053] The ultrasonic detection method of the foam concrete after construction of the high fill platform in this embodiment is:

[0054] Figure 1 As shown, a three-dimensional rectangular coordinate system is established for the high fill platform back, with the longitudinal direction of the roadbed as the x-axis, the transverse direction of the roadbed as the z-axis, and the vertical direction as the y-axis.

[0055] One side of the platform back, i.e., the roadbed side 1, is used as the detection surface, and the detection holes are distributed in a rectangular array on the detection surface. In the rectangular array, i represents the row number where the detection hole is located, and j represents the column where the detection hole is located; i = 1, 2, ... N; j = 1, 2, ... N;

[0056] With the center point of the detection hole mouth as the incident point A and the center point of the bottom of the detection hole as the end point B, a hole is drilled from the incident point A along the direction of the AB line toward the back of the platform to form a detection hole 3 with an incident angle of α and a depth of D; an acoustic detection tube is buried in the detection hole 3, and ultrasonic detection is performed using the acoustic detection tube to obtain ultrasonic detection data of the platform back, thereby realizing post-construction ultrasonic detection of foam concrete on the back of the high fill platform.

[0057] In specific implementation, the corresponding technical measures include:

[0058] Set the center distance between two adjacent detection holes in the same row, that is, the row spacing L h for:

[0059]

[0060] Set the center distance between two adjacent detection holes in the same row, that is, the row spacing L v for:

[0061]

[0062] in:

[0063] L h It is the center row distance between two adjacent detection holes;

[0064] L v is the center row distance between two adjacent detection holes;

[0065] [·] indicates rounding operation; m is the number of pouring layers of the platform back;

[0066] h is the height of the table back, b is the width of the table back, and the section coefficient a is 1.1;

[0067] α is the incident angle, which refers to the angle between the axis of the detection hole and the z axis. The axis of the detection hole is in the zoy plane and is inclined downward from one end of the hole mouth of the detection hole. Inclined downward means that the position of the hole mouth of the detection hole is higher than the position of the bottom of the hole.

[0068] The coordinates of the center point of the detection hole in the i-th row and j-th column of the rectangular array in the three-dimensional rectangular coordinate system are marked as (x ij ,y ij ,z ij ); then the coordinate matrix formed by the center point coordinates of each detection orifice in the rectangular array is:

[0069]

[0070] in:

[0071] t is the thickness of the protective layer of the reinforcement layer, which is used to protect the steel bars and refers to the distance from the outermost steel bars to the surface of the foam concrete;

[0072] T is the protection distance of the detection hole drilling, T = t + 5.5l, l is the spacing of the steel bars in the reinforcement layer;

[0073] D0 is the thickness of the road base filling material at the top of the abutment; D1 is the thickness of the road base filling material from the reinforcement layer to the bottom of the road base filling material at the top of the abutment.

[0074] If there is only one reinforced layer, the incident angle α is determined as follows:

[0075] The coordinates of the incident point A, i.e. the incident point coordinates, are marked as: (T, D0+D1-2t, 0)

[0076] The coordinates of the intersection of the AB line and the reinforced layer are marked as: (T, D0+D1, t+0.5pl)

[0077] p is the set of odd numbers in the natural number set;

[0078] Then the incident angle α is:

[0079] Thus, the function family of the incident angle α is obtained, and the detection hole is drilled at the incident angle α so that the detection hole is located at the center of the adjacent steel bars;

[0080] According to the detection hole diameter d k and the diameter of the reinforcement layer steel bar d s The safe fluctuation range β of the function family of the incident angle α is set to:

[0081]

[0082] in:

[0083]

[0084] And set the lower limit of the incident angle α minα to:

[0085] See also Figure 3 , there are two layers for the reinforced layer, namely the upper reinforced layer and the lower reinforced layer;

[0086] The method for obtaining the function family of the incident angle α and the safe fluctuation range β for the reinforced layer as one layer in this embodiment is applied to the upper reinforced layer and the lower reinforced layer respectively;

[0087] For the lower reinforcement layer, the coordinates of the intersection of the AB line and the lower reinforcement layer are marked as: (T, D0+D1+D2, )

[0088] D1 is the thickness of the reinforcement layer, i.e. the upper reinforcement layer to the bottom of the roadbed filler at the top of the abutment;

[0089] D2 is the distance between two reinforcement layers;

[0090] Use exhaustive method to confirm through verification is in the interval , it indicates that the incident angle α meets the requirements.

[0091] Set the depth D of the detection hole to:

[0092] See also Figure 4 A PVC tube 5 is placed in the detection hole. On the inner wall of the PVC tube, pulley blocks are set at intervals along the axial direction of the detection hole. The spacing between adjacent pulley blocks is not less than 2 meters. Each pulley block consists of three pulleys 6 evenly distributed along the circumference. The pulley block protects the acoustic detection tube 4 when it is lowered, and also places the acoustic detection tube 4 in the center of the detection hole to ensure the accuracy of the detection data. Water is filled between the detection tube and the acoustic detection tube, and water is used as the detection medium for ultrasonic detection.

[0093] This embodiment is for the layout of detection holes for a table back with a regular geometric shape; for a table back with an irregular geometric shape, the geometric shape of the table back is first decomposed and divided into a connection between a regular geometric shape and an irregular geometric shape, and the detection holes are arranged in the regular geometric shape part using the method of this embodiment, and detection holes are appropriately added in the irregular geometric shape part. The drilling process of the detection holes is required to avoid affecting the reinforcement layer.

[0094] Engineering Application

[0095] A road project uses lightweight foam concrete as the backfill material, with a design strength of ≥1.2MPa (28d), a backfill design height = 30.0m, a design width b = 10.0m, and a reinforced layer is set on the top of the back of the roadbed, with: l = 100.0mm, t = 50.0mm, d s=8.0mm, D0=1.5m, D1=2.0m; the single filling height of lightweight foam concrete is 0.5m, and the roadbed is poured layer by layer from bottom to top. The design mix ratio is: water-cement ratio 0.65, cement 365kg / m3, cement slurry mixing water 237kg / m3, foaming agent 0.933kg / m3, foaming agent dilution water 46.65kg / m3, the wet density of the bubble mixed lightweight soil slurry is 6.5kN / m3, the flow value is 179mm, and the foam group density is 50kg / m3. The construction mix ratio of lightweight foam concrete is shown in the following table.

[0096] serial number <![CDATA[Cement consumption (kg / m 3 )]]> <![CDATA[Water consumption (kg / m 3 )]]> <![CDATA[Bubble group volume (L / m 3 )]]> X1 365 237 645

[0097] The cement used is Conch brand PO42.5 ordinary Portland cement, the foaming agent used is HTW-1 type composite foaming agent, and the foaming agent dilution ratio is 1:50.

[0098] Set the detection hole diameter d k 40mm;

[0099] The coordinates of the incident point A are (0.6, 3.4, 0);

[0100] The coordinates of the intersection of line AB and the reinforcement layer are: (0.6, 3.5, 0.05+0.05p);

[0101] The minimum lower limit of the incident angle α is:

[0102] Select the incident angle α as 45.00° and 26.57°, and calculate the value of the safe fluctuation range β as shown in Table 1

[0103] Table 1

[0104] p-value 1 3 Angle of incidence α 45.00° 26.57° Safety fluctuation range β 42.29°～52.63° 25.77～27.75°

[0105] According to Table 1, the incident angle α=45° is selected.

[0106] Then determine L according to the geometric relationship of the back section h and L v The values ​​are:

[0107]

[0108]

[0109] Set the depth D of the detection hole to: Ultrasonic testing is performed accordingly.

Claims

1. A post-construction ultrasonic detection method for foamed concrete on the back of a high fill platform, characterized by: A side surface of the platform back is used as the detection surface, and the detection holes are distributed in a rectangular array on the detection surface. In the rectangular array, i represents the row number where the detection hole is located, and j represents the column where the detection hole is located; i=1,2,...N; j=1,2,...N; the center point of the hole opening of the detection hole is used as the incident point A, and the center point of the bottom of the detection hole is used as the end point B. From the incident point A, a hole is drilled toward the back of the platform along the direction of the AB line to form a detection hole with an incident angle of α and a depth of D; an acoustic detection tube is buried in the detection hole, and ultrasonic detection is performed using the acoustic detection tube to obtain ultrasonic detection data of the platform back, so as to realize ultrasonic detection of foam concrete on the back of the high fill platform after construction; A three-dimensional rectangular coordinate system is established for the back of the high fill platform, with the longitudinal direction of the roadbed as the x-axis, the transverse direction of the roadbed as the z-axis, and the vertical direction as the y-axis; Set the center distance between two adjacent detection holes in the same row, that is, the row spacing L h for: Set the center distance between two adjacent detection holes in the same row, that is, the row spacing L v for: in: L h It is the center row distance between two adjacent detection holes; L v is the center row distance between two adjacent detection holes; [·] indicates rounding operation; m is the number of pouring layers of the platform back; h is the height of the table back, b is the width of the table back, and the section coefficient a is 1.1; α is the incident angle, which refers to the angle between the axis of the detection hole and the z axis. The axis of the detection hole is in the zoy plane and tilts downward from one end of the hole mouth of the detection hole.

2. The ultrasonic detection method for high fill platform foam concrete after construction according to claim 1 is characterized by: The coordinates of the center point of the detection orifice located in the i-th row and j-th column of the rectangular array in the three-dimensional rectangular coordinate system are marked as (x ij ,y ij ,z ij ); then the coordinate matrix formed by the center point coordinates of each detection orifice in the rectangular array is: in: t is the thickness of the protective layer of the reinforcement layer, which is used to protect the steel bars and refers to the distance from the outermost steel bars to the surface of the foam concrete; T is the protection distance of the detection hole drilling, T = t + 5.5l, l is the spacing of the steel bars in the reinforcement layer; D0 is the thickness of the road base filling material at the top of the abutment; D1 is the thickness of the road base filling material from the reinforcement layer to the bottom of the road base filling material at the top of the abutment.

3. The post-construction ultrasonic detection method for foamed concrete on the back of a high-fill platform according to claim 2 is characterized by: If there is only one reinforced layer, the incident angle α is determined as follows: The coordinates of the incident point A, i.e. the incident point coordinates, are marked as: (T, D0+D1-2t, 0) The coordinates of the intersection of the AB line and the reinforced layer are marked as: (T, D0+D1, t+0.5pl) p is the set of odd numbers in the natural number set; Then the incident angle α is: Thus, a function family of the incident angle α is obtained, and a hole is drilled according to the incident angle α so that the detection hole is located at the center of the adjacent steel bars; According to the detection hole diameter d k and the diameter of the reinforcement layer steel bar d s The safe fluctuation range β of the function family of the incident angle α is set to: in: And set the lower limit of the incident angle α minα to:

4. The post-construction ultrasonic detection method for foamed concrete on the back of a high-fill platform according to claim 3 is characterized by: There are two layers for the reinforcement layer, namely the upper reinforcement layer and the lower reinforcement layer; The method of obtaining the function family of the incident angle α and the safe fluctuation range β for the reinforced layer as one layer in claim 3 is applied to the upper reinforced layer and the lower reinforced layer respectively; For the lower reinforced layer, the coordinates of the intersection of line AB and the lower reinforced layer are marked as: D1 is the thickness of the reinforcement layer, i.e. the upper reinforcement layer to the bottom of the roadbed filler at the top of the abutment; D2 is the distance between two reinforcement layers; Use exhaustive method to confirm through verification is in the interval , it indicates that the incident angle α meets the requirements.

5. The post-construction ultrasonic detection method for foamed concrete on the back of a high-fill platform according to claim 1 is characterized by: Set the depth D of the detection hole to:

6. The post-construction ultrasonic detection method for foamed concrete on the back of a high-fill platform according to claim 1 is characterized by: On the inner side wall of the detection hole, pulley blocks are arranged at intervals along the axial direction of the detection hole, so that the acoustic detection tube is located at the center of the detection hole.

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