CN111638119A - Slurry-soil interface strain testing method for earthen site anchoring system - Google Patents
Slurry-soil interface strain testing method for earthen site anchoring system Download PDFInfo
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- CN111638119A CN111638119A CN202010719268.6A CN202010719268A CN111638119A CN 111638119 A CN111638119 A CN 111638119A CN 202010719268 A CN202010719268 A CN 202010719268A CN 111638119 A CN111638119 A CN 111638119A
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
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Abstract
The invention discloses a slurry-soil interface strain testing method for an earthen site anchoring system, which solves the problem of inaccurate strain value monitoring of a slurry-earthen site interface in the prior art. The invention comprises the following steps: s1: manufacturing a strain gauge; s2: inserting the anchor rod into the anchor hole, and cleaning and absorbing dust in the anchor hole; s3: adhering the plurality of strain gauges manufactured in the step S1 to the inner wall of the anchor hole, so that the strain testing directions of the strain gauges are parallel to the axis of the anchor hole; s4: performing pressure grouting in the anchor hole in the step S3 to enable the anchor hole to be uniformly filled with grout, wherein the strain gauge is positioned in a grout-soil surface formed by the grout and the inner wall of the anchor hole; s5: and maintaining the grout in the anchor hole to enable the grout to reach a detection state, wherein the anchor rod in the grout reaching the detection state is a detection state anchor rod. The invention has the advantages of ingenious design, simple and effective detection mode and accurate test data, is a great innovation for monitoring the slurry-soil interface strain of the earthen site anchoring system, and has higher popularization value.
Description
Technical Field
The invention relates to the technical field of a strain test of an earthen site anchoring system, in particular to a slurry-soil interface strain test method of the earthen site anchoring system.
Background
In arid and semiarid regions in northwest of China, a large number of earthen sites are left as one of important types of cultural heritages of China, and the earthen sites have extremely high historical, scientific, artistic and social values. Such as the great wall and affiliated buildings of the Qin to Ming dynasties, temple sites and ancient castles of different historical periods. These cultural heritages, which use earth as the main building material, are the direct demonstration of the civilization origin and derivation of human beings. However, these nonrenewable earthen sites are in the open air and are affected by various natural forces and human activities such as wind erosion, rain erosion, freeze thawing, earthquakes and the like for a long time, and unstable blocks cut directly from cracks or fissures are generally developed in the earthen sites. Therefore, research on an ideal reinforcing method for an unstable block in an earthen site is urgent.
The anchoring technology has the characteristics of weak disturbance, strong concealment, high anchoring force and the like, and is widely applied to the field of stability control of the earthen site. However, due to the complexity of the anchoring problem of the earthen site, the understanding of the anchoring action mechanism of the anchor rod in the earthen site is still unclear at present, the development of the anchoring technology of the earthen site is severely restricted, and the theoretical level of the anchor rod support design is far behind the engineering practice.
When the site soil-enclosed rock body moves to a free space, the force is transmitted from the site soil body to the bonding material firstly and then from the bonding material to the anchor rod, and the complex transmission process of 3 media and 2 interfaces is involved, wherein the transmission mechanism and the distribution rule of the stress of the slurry-soil interface are the key points of the research on the anchoring action mechanism. However, most of the current scholars at home and abroad concentrate on researching the stress transmission and distribution rules between the anchor rods and the bonding materials, and the research on the stress transmission and distribution rules of the anchoring body interface between the site soil body and the bonding materials is very little, and the fundamental reason is that the strain of the slurry-site soil interface cannot be monitored in the anchoring and drawing test of the site soil, and then the strain value of the slurry-site soil interface cannot be accurately obtained.
Disclosure of Invention
Aiming at the defects in the background art, the invention provides a slurry-soil interface strain testing method for an earthen site anchoring system, which solves the problem of inaccurate strain value monitoring of a slurry-earthen site interface in the prior art.
The technical scheme of the invention is realized as follows: a slurry-soil interface strain test method for an earthen site anchoring system comprises the following steps:
s1: manufacturing a strain gauge;
s2: inserting the anchor rod into the anchor hole, and cleaning and absorbing dust in the anchor hole;
s3: adhering the plurality of strain gauges manufactured in the step S1 to the inner wall of the anchor hole, so that the strain testing directions of the strain gauges are parallel to the axis of the anchor hole;
s4: performing pressure grouting in the anchor hole in the step S3 to enable the anchor hole to be uniformly filled with grout, wherein the strain gauge is positioned in a grout-soil surface formed by the grout and the inner wall of the anchor hole;
s5: maintaining the slurry in the anchor hole to enable the slurry to reach a detection state, wherein the anchor rod in the slurry reaching the detection state is a detection state anchor rod;
s6: calibrating the strain gauge in the step S1 through a direct shear test, obtaining a calibrated strain value, and making the calibrated strain value into a calibration table;
s7: pulling the detection state anchor rod along the axial direction of the anchor rod, and carrying out strain detection on the corresponding slurry-soil interface by using a strain gauge in the slurry-soil surface to obtain a detection strain value;
s8: and (4) comparing the detected strain value in the step S7 with the calibration table in the step S6 to obtain a true value of the slurry-soil interface strain, and further completing the slurry-soil interface strain test.
A slurry-soil interface strain test method for an earthen site anchoring system comprises the following steps:
b1: manufacturing a strain gauge;
b2: b1, calibrating the strain gauge in the step B1 through a direct shear test, obtaining a calibrated strain value, and making the calibrated strain value into a calibration table;
b3: inserting the anchor rod into the anchor hole, and cleaning and absorbing dust in the anchor hole;
b4: b, adhering the plurality of strain gauges manufactured in the step B1 to the inner wall of the anchor hole, so that the strain testing directions of the strain gauges are parallel to the axis of the anchor hole;
b5: performing pressure grouting in the anchor hole in the step B4 to enable the anchor hole to be uniformly filled with grout, wherein the strain gauge is positioned in a grout-soil surface formed by the grout and the inner wall of the anchor hole;
b6: maintaining the slurry in the anchor hole to enable the slurry to reach a detection state, wherein the anchor rod in the slurry reaching the detection state is a detection state anchor rod;
b7: pulling the detection state anchor rod along the axial direction of the anchor rod, and carrying out strain detection on the corresponding slurry-soil interface by using a strain gauge in the slurry-soil surface to obtain a detection strain value;
b8: and (4) comparing the detected strain value in the step S7 with the calibration table in the step B2 to obtain a true value of the slurry-soil interface strain, and further completing the slurry-soil interface strain test.
The strain gauge in the step S1 and the step B1 comprises a strain test piece, a thin-layer cushion is arranged at the bottom of the strain test piece, a moisture-proof layer is arranged on the upper surface of the strain test piece, and the strain test piece is connected with an external information acquisition device through a lead.
Thin layer cushion plane geometry is 2~3 times of the plane geometry of test piece of meeting an emergency, and the test piece of meeting an emergency pastes in the geometric center of thin layer cushion, and the dampproof course is flexible dampproofing glue.
The steps of calibrating the strain gauge in the step S6 and the step B2 in the direct shear test are as follows: s6.1: adopting a cutting ring to collect a soil sample of the position of the tested earthen site to manufacture a cutting ring sample;
s6.2: removing the soil sample with half height at the lower part of the cutting ring sample, ensuring the cut surface of the soil sample with the remaining half height to be flat, and performing surface cleaning and dust collection treatment on the cut surface;
s6.3: taking the geometric center of the tangent plane as a standard, making a cross mark, adhering the strain gauge to the geometric center of the tangent plane, and keeping the test direction of the strain gauge and the axial coincidence of the signal line and the cross mark;
s6.4: injecting the slurry into the cutting ring and onto the soil sample with the strain gauge adhered thereon to obtain a slurry-soil combination, and positioning the strain gauge in the slurry-soil surface formed by the slurry and the soil sample;
s6.5: scraping the slurry on the surface of the cutting ring, and curing the prepared slurry-soil combination under the same conditions as those in the step S5 or the step B6;
s6.6: performing a direct shear test on the maintained slurry-soil combination by using a direct shear tester, and keeping the axis of the signal line and the test direction of the strain gauge consistent with the shearing direction of the direct shear test in the process of mounting the slurry-soil combination to a direct shear box; in the testing process, strain values of a slurry-soil interface are collected through a strain gauge, and strain calibration values of a slurry-soil combination are collected through a direct shear tester;
s6.7: and averaging strain values of the strain gauge acquired by the strain gauge to obtain a strain average value of the strain gauge, averaging strain calibration values acquired by the direct shear tester to obtain a strain calibration average value, and establishing a calibration table in which the strain average values of the strain gauge and the strain calibration average values are in one-to-one correspondence.
In the step S3 and/or the step B4, the strain gauges are positioned on the same generatrix of the anchor hole, and the generatrix is parallel to the axis of the anchor hole;
and in the step S3 and/or the step B4, the sticking area of the strain gauge stuck to the inner wall of the anchor hole is positioned on the lower semicircle taking the center of the anchor hole as the center of a circle, and the sticking area is an arc surface with the central angle of 30-50 degrees. Namely, the sticking areas are symmetrically arranged on two sides of the axial surface in the anchor hole, the angle alpha between the bottommost surface of the sticking areas and the axial surface in the anchor hole is 30-40 degrees, and the angle beta between the highest surface of the sticking areas and the axial surface in the anchor hole is 70-80 degrees. Preferably, the pasting area is an arc surface with a central angle of 30 degrees, an angle alpha between the bottommost surface of the pasting area and an axial surface in the anchor hole is 40 degrees, and an angle beta between the topmost surface of the pasting area and the axial surface in the anchor hole is 70 degrees.
The specific steps of the step S2 and the step B3 are that a large amount of floating soil remained in the anchor hole to be tested is firstly removed, then dust absorption treatment is carried out on the preset sticking area within 15-30 minutes before the step of sticking the strain gauge to the hole wall, and the surface dust of the sticking area is removed.
The invention has the following beneficial effects: 1. in the invention, the hole cleaning and dust collection, the selection of the sticking area, the use of the thin-layer cushion and the size proportion of the strain testing unit can be suitable for sticking strain gauges with various soil qualities, pore diameters with various sizes and rough pore walls, and the invention has wide application range and flexible use. And then grouting under pressure, and only arranging the strain gauge in the slurry-soil interface layer, thereby realizing the strain test of the slurry-soil interface of the anchoring system of the earthen site, and having simple operation and accurate data acquisition. 2. In the invention, the strain calibration step accurately realizes the one-to-one corresponding value calibration of the strain value of the grout-soil interface measured by the direct shear test equipment and the average value of the strain value of the grout-soil interface collected by the strain gauge by using the mode that the preset grout-soil interface of the direct shear test is taken as a shearing surface, ensures the precision of the strain value of the grout-soil interface of the anchoring system of the earth site tested by the strain gauge, and improves the test efficiency and the test precision of the whole test. The invention has the advantages of ingenious design, simple and effective detection mode and accurate test data, is a great innovation for monitoring the slurry-soil interface strain of the earthen site anchoring system, and has higher popularization value.
Drawings
In order to illustrate the embodiments of the invention more clearly, the drawings that are needed in the description of the embodiments will be briefly described below, it being apparent that the drawings in the following description are only some embodiments of the invention, and that other drawings may be derived from those drawings by a person skilled in the art without inventive effort.
FIG. 1 is a flow chart of the test of the present invention in example 1.
FIG. 2 is a flow chart of the test of the present invention in example 2.
Fig. 3 is a schematic top view of a strain gauge according to the present invention.
Fig. 4 is a schematic cross-sectional view of a strain gauge of the present invention.
FIG. 5 is a diagram illustrating the calibration of strain values in a direct shear test.
Fig. 6 is a schematic view of a slurry-soil combination with strain gauges.
FIG. 7 is a schematic view of a strain gauge attachment area.
Fig. 8 is a schematic view showing a state where a plurality of strain gauges are attached.
FIG. 9 is a diagram of a resistance strain gauge and a strain gauge paste effect on a soil-slurry interface.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive effort based on the embodiments of the present invention, are within the scope of the present invention.
As shown in fig. 1 and 9, in example 1, a method for testing slurry-soil interface strain of an earthen site anchoring system includes the following steps:
s1: manufacturing a strain gauge; as shown in fig. 3 and 4, that is, strain gauge 1 includes strain test piece 101, strain test piece 101 may be a strain gage or a resistance strain gauge, thin cushion 102 is disposed at the bottom of strain test piece 101 for being attached to the wall of the anchor hole, moisture-proof layer 103 is disposed on the upper surface of strain test piece 101, moisture-proof layer 103 is made of flexible moisture-proof glue, and has certain flexibility for facilitating strain detection of the grout-soil interface. The strain test piece 101 is connected with an external information acquisition device through a lead 104, and the information acquisition device can adopt a PLC or a computer to acquire and process data. The planar geometric dimension of thin layer cushion 102 is 2~3 times of the planar geometric dimension of test 101 that meets an emergency, and the test 101 that meets an emergency is pasted in the geometric center of thin layer cushion 102, and the planar projection of test unit and thin layer cushion that meets an emergency is the thin slice structure for similar figure, improves the stability and the precision of test that meets an emergency, and is convenient for paste to the anchor eye inner wall on.
S2: cleaning holes and absorbing dust: inserting the anchor rod into the anchor hole, and cleaning and absorbing dust in the anchor hole; the specific steps are that a large amount of floating soil remained in the anchor hole to be tested is removed, dust absorption treatment is carried out on a preset adhering area within 15-30 minutes before the step of adhering the strain gauge to the hole wall, redundant floating dust is absorbed, and surface micro dust of the adhering area is removed, so that the strain gauge is conveniently and stably and accurately adhered.
S3: the strain gauge is adhered to the inner wall of the anchor hole: adhering the plurality of strain gauges manufactured in the step S1 to the inner wall of the anchor hole, so that the strain testing directions of the strain gauges are parallel to the axis of the anchor hole; the strain gauges are located on the same bus of the anchor hole, and the bus is parallel to the axis of the anchor hole. The strain gauges can be divided into 2 groups or 3 groups, the strain gauges in each group are located on the same bus of the anchor hole, the buses where the strain gauges in the 2 groups or 3 groups are located are parallel to each other, and strain conditions of slurry-soil interfaces of different buses are monitored simultaneously.
As shown in fig. 7 and 8, in the step S3, the adhesion area where the strain gauge is adhered to the inner wall of the anchor hole is located on the lower semicircle with the center of the anchor hole as the center of the circle, and the adhesion area is an arc surface with a central angle of 30 ° to 50 °, so that the strain gauge is not easy to fall off and the slurry does not cause too much pressure on the strain gauge. The sticking areas are symmetrically arranged on two sides of a middle axial plane of the anchor hole, and the middle axial plane is a vertical tangent plane where the central axis of the anchor hole is located. The angle alpha between the bottommost surface of the sticking area and the axial surface in the anchor hole is 30-40 degrees, and the angle beta between the highest surface of the sticking area and the axial surface in the anchor hole is 70-80 degrees. Preferably, the pasting area is an arc surface with a central angle of 30 degrees, an angle alpha between the bottommost surface of the pasting area and an axial surface in the anchor hole is 40 degrees, and an angle beta between the topmost surface of the pasting area and the axial surface in the anchor hole is 70 degrees. In this adhesion area, the strain gauge can be firmly adhered to the inside of the anchor hole and accurately measure the strain of the grout-soil interface.
S4: grouting under pressure: and (5) performing pressure grouting in the anchor hole in the step S3, namely pouring the prepared grout into the anchor hole under the action of a grouting machine and under a certain pressure, so that the grout uniformly fills the anchor hole, the tamping grouting of the anchor hole is ensured, and the strain gauge is positioned in a grout-soil surface formed by the grout and the inner wall of the anchor hole.
S5: curing slurry: and (5) maintaining the grout in the anchor hole, wherein the maintaining conditions are consistent with the maintaining conditions calibrated in the direct shear test in the step S6, ensuring the accuracy of the control variable test, and enabling the grout to reach a detection state, wherein the anchor rod in the grout reaching the detection state is the anchor rod in the detection state.
S6: strain calibration: as shown in fig. 5 and 6, the strain gauge in step S1 is calibrated by the direct shear test, and a calibration strain value is obtained, and the calibration strain value is made into a calibration table. And the calibration table is used as a reference table of the detection strain value measured by the strain gauge, and the corresponding calibration strain value is quickly obtained according to the detection strain value and the calibration table, namely the true value of the slurry-soil interface strain.
S7: drawing test acquisition strain: pulling the detection state anchor rod along the axial direction of the anchor rod, and carrying out strain detection on the corresponding slurry-soil interface by using a strain gauge in the slurry-soil surface to obtain a detection strain value;
s8: obtaining the interface strain: and (4) comparing the detected strain value in the step S7 with the calibration table in the step S6 to obtain a true value of the slurry-soil interface strain, and further completing the slurry-soil interface strain test.
As shown in fig. 2 and 9, in embodiment 2, a method for testing a slurry-soil interface strain of an earthen site anchoring system is different from that in embodiment 1 in that calibration of a direct shear test is performed, and then strain gauge detection is performed on an anchor hole, and the steps are as follows:
b1: manufacturing a strain gauge; as shown in fig. 3 and 4, that is, strain gauge 1 includes strain test piece 101, strain test piece 101 may be a strain gage or a resistance strain gauge, thin cushion 102 is disposed at the bottom of strain test piece 101 for being attached to the wall of the anchor hole, moisture-proof layer 103 is disposed on the upper surface of strain test piece 101, moisture-proof layer 103 is made of flexible moisture-proof glue, and has certain flexibility for facilitating strain detection of the grout-soil interface. The strain test piece 101 is connected with an external information acquisition device through a lead 104, and the information acquisition device can adopt a PLC or a computer to acquire and process data. The planar geometric dimension of thin layer cushion 102 is 2~3 times of the planar geometric dimension of test 101 that meets an emergency, and the test 101 that meets an emergency is pasted in the geometric center of thin layer cushion 102, and the planar projection of test unit and thin layer cushion that meets an emergency is the thin slice structure for similar figure, improves the stability and the precision of test that meets an emergency, and is convenient for paste to the anchor eye inner wall on.
B2: strain calibration: as shown in fig. 5 and 6, calibrating the strain gauge in step B1 by a direct shear test, obtaining a calibrated strain value, and making the calibrated strain value into a calibration table; and the calibration table is used as a reference table of the detection strain value measured by the strain gauge, and the corresponding calibration strain value is quickly obtained according to the detection strain value and the calibration table, namely the true value of the slurry-soil interface strain.
B3: cleaning holes and absorbing dust: inserting the anchor rod into the anchor hole, and cleaning and absorbing dust in the anchor hole; the specific steps are that a large amount of floating soil remained in the anchor hole to be tested is removed, dust absorption treatment is carried out on a preset adhering area within 15-30 minutes before the step of adhering the strain gauge to the hole wall, redundant floating dust is absorbed, and surface micro dust of the adhering area is removed, so that the strain gauge is conveniently and stably and accurately adhered.
B4: the strain gauge is adhered to the inner wall of the anchor hole: as shown in fig. 7 and 8, the plurality of strain gauges manufactured in step B1 are adhered to the inner wall of the anchor eye such that the strain measurement directions of the strain gauges are parallel to the axis of the anchor eye. The strain gauges are located on the same bus of the anchor hole, and the bus is parallel to the axis of the anchor hole. The strain gauges can be divided into 2 groups or 3 groups, the strain gauges in each group are located on the same bus of the anchor hole, the buses where the strain gauges in the 2 groups or 3 groups are located are parallel to each other, and strain conditions of slurry-soil interfaces of different buses are monitored simultaneously.
As shown in fig. 7 and 8, in the step B4, the adhesion area where the strain gauge is adhered to the inner wall of the anchor hole is located on the lower semicircle with the center of the anchor hole as the center of the circle, and the adhesion area is an arc surface with a central angle of 30-50 degrees, so that the strain gauge is not easy to fall off, and the slurry does not cause too much pressure to the strain gauge. The sticking areas are symmetrically arranged on two sides of a middle axial plane of the anchor hole, and the middle axial plane is a vertical tangent plane where the central axis of the anchor hole is located. The angle alpha between the bottommost surface of the sticking area and the axial surface in the anchor hole is 30-40 degrees, and the angle beta between the highest surface of the sticking area and the axial surface in the anchor hole is 70-80 degrees. Preferably, the pasting area is an arc surface with a central angle of 30 degrees, an angle alpha between the bottommost surface of the pasting area and an axial surface in the anchor hole is 40 degrees, and an angle beta between the topmost surface of the pasting area and the axial surface in the anchor hole is 70 degrees. In this adhesion area, the strain gauge can be firmly adhered to the inside of the anchor hole and accurately measure the strain of the grout-soil interface
B5: grouting under pressure: and C, performing pressure grouting in the anchor hole in the step B4, namely pouring the prepared grout into the anchor hole under the action of a grouting machine and under a certain pressure, so that the grout uniformly fills the anchor hole, the tamping grouting of the anchor hole is ensured, and the strain gauge is positioned in a grout-soil surface formed by the grout and the inner wall of the anchor hole.
B6: curing slurry: and B2, maintaining the grout in the anchor hole, wherein the maintenance conditions are consistent with those calibrated in the direct shear test in the step B2, ensuring the accuracy of the control variable test, and enabling the grout to reach a detection state, wherein the anchor rod in the grout reaching the detection state is the anchor rod in the detection state.
B7: drawing test acquisition strain: pulling the detection state anchor rod along the axial direction of the anchor rod, and carrying out strain detection on the corresponding slurry-soil interface by using a strain gauge in the slurry-soil surface to obtain a detection strain value;
b8: obtaining the interface strain: and (4) comparing the detected strain value in the step S7 with the calibration table in the step B2 to obtain a true value of the slurry-soil interface strain, and further completing the slurry-soil interface strain test.
Example 3: the concrete steps of calibrating the straying meter in the step S6 and the step B2 of the slurry-soil interface strain testing method of the earthen site anchoring system described in the embodiment 1 and the embodiment 2 are as follows: as shown in FIG. 5, S is shear displacement, T is horizontal shear force, and P is positive pressure. Tau is the interface shear stress, sigma is the interface normal stress;
s6.1: adopting a cutting ring to collect a soil sample of the position of the tested earthen site to manufacture a cutting ring sample;
s6.2: removing the soil sample with half height at the lower part of the cutting ring sample, ensuring the cut surface of the soil sample with the remaining half height to be flat, and performing surface cleaning and dust collection treatment on the cut surface;
s6.3: taking the geometric center of the tangent plane as a standard, making a cross mark, adhering the strain gauge to the geometric center of the tangent plane, and keeping the test direction of the strain gauge and the axial coincidence of the signal line and the cross mark;
s6.4: injecting the slurry into the cutting ring and onto the soil sample with the strain gauge adhered thereon to obtain a slurry-soil combination, and positioning the strain gauge in the slurry-soil surface formed by the slurry and the soil sample;
s6.5: scraping the slurry on the surface of the cutting ring, and curing the prepared slurry-soil combination under the same conditions as those in the step S5 or the step B6;
s6.6: performing a direct shear test on the maintained slurry-soil combination by using a direct shear tester, and keeping the axis of the signal line and the test direction of the strain gauge consistent with the shearing direction of the direct shear test in the process of mounting the slurry-soil combination to a direct shear box; in the testing process, strain values of a slurry-soil interface are collected through a strain gauge, and strain calibration values of a slurry-soil combination are collected through a direct shear tester;
s6.7: and averaging strain values of the strain gauge acquired by the strain gauge to obtain a strain average value of the strain gauge, averaging strain calibration values acquired by the direct shear tester to obtain a strain calibration average value, and establishing a calibration table in which the strain average values of the strain gauge and the strain calibration average values are in one-to-one correspondence. For example, the positive pressures selected for the direct shear test are 100kPa, 200kPa, 300kPa, 400kPa, respectively, and the shear force is TnIn the process, strain calibration values displayed on direct shear test equipment under 4 types of positive pressure are An, Bn, Cn and Dn respectively; the strain values of the slurry-soil interface collected by the strain gauges under the 4 positive pressures are an, bn, cn and dn respectively; strain mean of strain gaugen=(an+bn+cn+dn)/4,Mean value of strain calibrationEIs composed ofEn=(An+Bn+Cn+Dn)/4Then establishing strain mean value and strain calibration mean value of strain gaugeEThe one-to-one calibration table is shown in the following table:
and when the strain is measured, selecting a corresponding strain calibration mean value as an actually measured strain mean value according to the strain value of the slurry-soil interface collected by the strain gauge.
The other steps are the same as in example 1 or 2.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (10)
1. A slurry-soil interface strain test method for an earthen site anchoring system is characterized by comprising the following steps: the method comprises the following steps:
s1: manufacturing a strain gauge (1);
s2: inserting the anchor rod into the anchor hole, and cleaning and absorbing dust in the anchor hole;
s3: adhering the plurality of strain gauges manufactured in the step S1 to the inner wall of the anchor hole, so that the strain testing directions of the strain gauges are parallel to the axis of the anchor hole;
s4: performing pressure grouting in the anchor hole in the step S3 to enable the anchor hole to be uniformly filled with grout, wherein the strain gauge is positioned in a grout-soil surface formed by the grout and the inner wall of the anchor hole;
s5: maintaining the slurry in the anchor hole to enable the slurry to reach a detection state, wherein the anchor rod in the slurry reaching the detection state is a detection state anchor rod;
s6: calibrating the strain gauge in the step S1 through a direct shear test, obtaining a calibrated strain value, and making the calibrated strain value into a calibration table;
s7: pulling the detection state anchor rod along the axial direction of the anchor rod, and carrying out strain detection on the corresponding slurry-soil interface by using a strain gauge in the slurry-soil surface to obtain a detection strain value;
s8: and (4) comparing the detected strain value in the step S7 with the calibration table in the step S6 to obtain a true value of the slurry-soil interface strain, and further completing the slurry-soil interface strain test.
2. A slurry-soil interface strain test method for an earthen site anchoring system is characterized by comprising the following steps: the method comprises the following steps:
b1: manufacturing a strain gauge (1);
b2: b1, calibrating the strain gauge in the step B1 through a direct shear test, obtaining a calibrated strain value, and making the calibrated strain value into a calibration table;
b3: inserting the anchor rod into the anchor hole, and cleaning and absorbing dust in the anchor hole;
b4: b, adhering the plurality of strain gauges manufactured in the step B1 to the inner wall of the anchor hole, so that the strain testing directions of the strain gauges are parallel to the axis of the anchor hole;
b5: performing pressure grouting in the anchor hole in the step B4 to enable the anchor hole to be uniformly filled with grout, wherein the strain gauge is positioned in a grout-soil surface formed by the grout and the inner wall of the anchor hole;
b6: maintaining the slurry in the anchor hole to enable the slurry to reach a detection state, wherein the anchor rod in the slurry reaching the detection state is a detection state anchor rod;
b7: pulling the detection state anchor rod along the axial direction of the anchor rod, and carrying out strain detection on the corresponding slurry-soil interface by using a strain gauge in the slurry-soil surface to obtain a detection strain value;
b8: and (4) comparing the detected strain value in the step S7 with the calibration table in the step B2 to obtain a true value of the slurry-soil interface strain, and further completing the slurry-soil interface strain test.
3. The earthen site anchoring system slurry-soil interface strain test method as claimed in claim 1 or 2, characterized in that: the strain gauge (1) in the steps S1 and B1 comprises a strain test piece (101), a thin cushion (102) is arranged at the bottom of the strain test piece (101), a moisture-proof layer (103) is arranged on the upper surface of the strain test piece (101), and the strain test piece (101) is connected with an external information acquisition device through a lead (104).
4. The earthen site anchoring system slurry-soil interface strain testing method of claim 3, characterized in that: the plane geometric dimension of the thin-layer cushion (102) is 2-3 times of that of the strain test piece (101), the strain test piece (101) is pasted at the geometric center of the thin-layer cushion (102), and the moisture-proof layer (103) is made of flexible moisture-proof glue.
5. The earthen site anchoring system slurry-soil interface strain testing method as claimed in claim 1, 2 or 4, characterized in that: the steps of calibrating the strain gauge in the step S6 and the step B2 in the direct shear test are as follows: s6.1: adopting a cutting ring to collect a soil sample of the position of the tested earthen site to manufacture a cutting ring sample;
s6.2: removing the soil sample with half height at the lower part of the cutting ring sample, ensuring the cut surface of the soil sample with the remaining half height to be flat, and performing surface cleaning and dust collection treatment on the cut surface;
s6.3: taking the geometric center of the tangent plane as a standard, making a cross mark, adhering the strain gauge to the geometric center of the tangent plane, and keeping the test direction of the strain gauge and the axial coincidence of the signal line and the cross mark;
s6.4: injecting the slurry into the cutting ring and onto the soil sample with the strain gauge adhered thereon to obtain a slurry-soil combination, and positioning the strain gauge in the slurry-soil surface formed by the slurry and the soil sample;
s6.5: scraping the slurry on the surface of the cutting ring, and curing the prepared slurry-soil combination under the same conditions as those in the step S5 or the step B6;
s6.6: performing a direct shear test on the maintained slurry-soil combination by using a direct shear tester, and keeping the axis of the signal line and the test direction of the strain gauge consistent with the shearing direction of the direct shear test in the process of mounting the slurry-soil combination to a direct shear box; in the testing process, strain values of a slurry-soil interface are collected through a strain gauge, and strain calibration values of a slurry-soil combination are collected through a direct shear tester;
s6.7: and averaging strain values of the strain gauge acquired by the strain gauge to obtain a strain average value of the strain gauge, averaging strain calibration values acquired by the direct shear tester to obtain a strain calibration average value, and establishing a calibration table in which the strain average values of the strain gauge and the strain calibration average values are in one-to-one correspondence.
6. The earthen site anchoring system slurry-soil interface strain testing method as claimed in claim 1, 2 or 4, characterized in that: in the step S3 and/or the step B4, the strain gauges are located on the same generatrix of the anchor hole, and the generatrix is parallel to the axis of the anchor hole.
7. The earthen site anchoring system slurry-soil interface strain testing method of claim 6, characterized in that: and in the step S3 and/or the step B4, the sticking area of the strain gauge stuck to the inner wall of the anchor hole is positioned on the lower semicircle taking the center of the anchor hole as the center of a circle, and the sticking area is an arc surface with the central angle of 30-50 degrees.
8. The earthen site anchoring system slurry-soil interface strain testing method of claim 7, characterized in that: the sticking areas are symmetrically arranged on two sides of the axial surface in the anchor hole, the angle alpha between the bottommost surface of the sticking areas and the axial surface in the anchor hole is 30-40 degrees, and the angle beta between the highest surface of the sticking areas and the axial surface in the anchor hole is 70-80 degrees.
9. The earthen site anchoring system slurry-soil interface strain testing method of claim 8, characterized in that: the pasting area is an arc surface with a central angle of 30 degrees, an angle alpha between the bottommost surface of the pasting area and an axial surface in the anchor hole is 40 degrees, and an angle beta between the topmost surface of the pasting area and the axial surface in the anchor hole is 70 degrees.
10. The earthen site anchoring system slurry-soil interface strain testing method as claimed in claim 1, 2, 4, 7, 8 or 9 wherein: the specific steps of the step S2 and the step B3 are that a large amount of floating soil remained in the anchor hole to be tested is firstly removed, then dust absorption treatment is carried out on the preset sticking area within 15-30 minutes before the step of sticking the strain gauge to the hole wall, and the surface dust of the sticking area is removed.
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Application publication date: 20200908 Assignee: Gansu Mogao Grottoes Cultural Heritage Protection Design Consulting Co.,Ltd. Assignor: LANZHOU University OF TECHNOLOGY Contract record no.: X2023980038592 Denomination of invention: A Method for Testing the Strain of the Grout Soil Interface in the Anchorage System of Earth Sites Granted publication date: 20210625 License type: Common License Record date: 20230727 |