CN108225651B - Test method and test device for testing tangential frost heaving force distribution of conical piles in frozen soil area - Google Patents
Test method and test device for testing tangential frost heaving force distribution of conical piles in frozen soil area Download PDFInfo
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- 238000012360 testing method Methods 0.000 title claims abstract description 61
- 239000002689 soil Substances 0.000 title claims abstract description 40
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- 238000007710 freezing Methods 0.000 claims abstract description 38
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- 229940099259 vaseline Drugs 0.000 claims description 18
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- 238000006073 displacement reaction Methods 0.000 claims description 13
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- 238000005259 measurement Methods 0.000 claims description 7
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- 239000011150 reinforced concrete Substances 0.000 claims description 5
- 229910000838 Al alloy Inorganic materials 0.000 claims description 4
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- 229910000831 Steel Inorganic materials 0.000 claims description 4
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- 238000012544 monitoring process Methods 0.000 claims description 4
- 239000002994 raw material Substances 0.000 claims description 4
- 239000010959 steel Substances 0.000 claims description 4
- 238000010257 thawing Methods 0.000 claims description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
- 239000007788 liquid Substances 0.000 claims 1
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- 239000012530 fluid Substances 0.000 description 5
- 238000013461 design Methods 0.000 description 3
- 230000003014 reinforcing effect Effects 0.000 description 3
- 229920005830 Polyurethane Foam Polymers 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
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- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 239000011496 polyurethane foam Substances 0.000 description 2
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- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
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- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
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Abstract
The invention discloses an indoor test method for testing tangential frost heave force distribution of a conical pile in a frozen soil area and a test device used by the same, and mainly solves the problem that a strain gauge cannot be used for testing tangential frost heave force distribution of a small conical pile model in the indoor test. The method comprises the steps of preparing a conical pile sample, treating the surface of the conical pile, carrying out anti-freezing and pulling treatment on a part of the conical pile, embedding the conical pile in a test soil sample, measuring the freezing and pulling force in a unidirectional freezing process, calculating the average tangential frost heaving force and measuring the average tangential frost heaving force of all the areas. The test method for measuring the average tangential frost heaving force of the conical pile in the divided areas adopted by the test can avoid the influence of temperature on the conventional strain gauge method, can more clearly observe the influence of the tangential frost heaving force of a certain area on the frost heaving of the pile, and is more beneficial to researching the distribution situation of the tangential frost heaving force along the pile side.
Description
Technical Field
The invention relates to a test method and a test device for testing tangential stress distribution of a pile foundation, in particular to a test method for testing tangential frost heaving force distribution of a conical pile in a frozen soil area.
Background
The frozen soil area of China accounts for about 75% of the area of the national soil, the engineering built in the frozen soil area is more and more increased, the application of the pile foundation is more and more extensive, and the damage phenomenon of the upper structure caused by the oversized uneven frozen pulling deformation of the pile foundation is more and more prominent. The conical pile is used as a novel pile foundation, has remarkable effect on the aspect of frost removal resistance and is widely applied, but the frost removal resistance mechanism of the conical pile is not unified yet. The tangential frost heaving force is used as a main parameter in the frost heaving process of the pile foundation, and is particularly important to carry out size distribution test research on the pile foundation in the depth direction, so that the stress mechanism of the conical pile foundation for frost heaving is thoroughly explored, and a powerful reference is provided for the construction design of the pile foundation in the frozen soil area.
At present, the method for testing the tangential frost heave force distribution of the pile foundation through an indoor test is less, a common method is to use a rebar meter or use a strain gauge for measurement, but the rebar meter has higher cost and measures that the rebar stress is not the tangential frost heave force of the pile foundation, and the strain gauge is inconvenient for temperature compensation, so that the accuracy of the tangential frost heave force measured by the two methods is questioned. It is therefore necessary to design a new test method for determining the tangential frost heave force distribution of a tapered pile with respect to the existing test apparatus.
Disclosure of Invention
The invention aims to solve the technical problem that the tangential frost heaving force of a pile foundation of a frozen soil area is distributed along with the size of the depth direction at present, and provides an indoor test method for testing the tangential frost heaving force of a conical pile of the frozen soil area without reinforcing steel bars and temperature compensation and a test device used by the same.
In order to solve the technical problems, the test method of the invention adopts the following technical scheme: which comprises the following steps:
1) Preparing a pile body sample: the density of the reinforced concrete pile is similar to that of the on-site reinforced concrete pile, aluminum alloy is used as a raw material for preparing the pile body, and circular grooves around the pile are carved every 3 cm to 6cm along the direction of the pile body;
2) Anti-freezing and pulling treatment of a pile body partial area; the area needing to measure the freeze-pulling force is kept as it is, and other areas are subjected to freeze-pulling treatment;
3) Conical piles are embedded in the test soil samples: placing the pile body in a pile body anti-pulling performance test device, uniformly placing soil samples around the pile body, and compacting in layers;
4) Measurement of the freeze-pull force in the unidirectional freezing process: the pile body pulling resistance test device is ensured to be frozen unidirectionally from the pile top to the pile bottom, and the pulling force is measured by adopting a counterforce steel frame and a load sensor;
5) Average tangential frost heaving force calculation: calculating the total tangential frost heaving force and the curved surface area of the frost heaving region, and calculating the average tangential frost heaving force according to the ratio of the total tangential frost heaving force and the curved surface area of the frost heaving region;
6) The average tangential frost heaving force was determined for all areas: repeating the second to fifth steps until the average tangential frost heaving force of all the areas is measured.
Preferably, the total length of the pile body in the step 1) is 25-35 cm, the small circle diameter is 3-8 cm, and the cone angle of the conical pile is 3-11 degrees.
Preferably, the depth of the circular groove of the pile body in the step 1) is 2-3 mm, the width is 2-4 mm, and the distance between two adjacent grooves is 3-6 cm.
Preferably, the anti-freezing and anti-freezing measures in the step 2) are that Vaseline is firstly smeared on an anti-freezing area, and then felt paper is wrapped on the area coated with Vaseline and bound and fixed.
Preferably, the soil sample in the step 3) adopts frost heave sensitive soil, the compaction degree is 93% -97%, layered compaction is required, and a temperature sensor is required to be arranged every 5-6 cm in the process of embedding the soil sample, and a moisture sensor is required to be arranged every 10 cm.
Preferably, in the step 4), the bottom of the pile body is kept at 1 ℃ in the unidirectional freezing process, the influence of normal frost heaving force is eliminated, and the load sensor and the temperature sensor adopt DT80 data collectors for data acquisition.
Preferably, the formula for calculating the unit tangential frost heaving force in the step 5) is as follows:
wherein τ i Average tangential freeze for the ith regionExpansion force (in MPa); g is the total weight of the pile body (unit is N); t is the frozen pulling force (unit is N) measured by the existing test device; s is S i Is the side surface area of the ith zone (in mm 2 )。
Preferably, in the repeated test of the step 6), vaseline on the surface of the sample needs to be cleaned up and then the step 2) is performed.
Preferably, when the felt paper is subjected to anti-freezing and anti-drawing treatment, the upper end and the lower end of the felt paper are positioned in the grooves, and the lower end of the felt paper is ensured to leave 1-2 cm of allowance in the grooves, and the allowance is folded for several times and bound in the grooves; before the felt paper is wrapped, vaseline is coated on the front and back sides of the felt paper; in order to ensure unidirectional freezing, thermal insulation cotton is adopted to perform thermal insulation treatment on the periphery of the pile body anti-pulling performance test device, and the pile body anti-pulling performance test device is placed in a high-low temperature alternating freezing and thawing circulation box.
The invention provides a pile body anti-pulling performance test device which comprises a sample tube, a fixed support for fixing the sample tube and a base positioned at the lower part of a pile body sample in the sample tube, wherein a refrigerating fluid circulating tube is arranged below the sample tube, and a water sensor is arranged on one side of the inner wall of the sample tube, and a temperature sensor is arranged on the other side of the inner wall of the sample tube; the pile body test sample is characterized in that a load sensor is arranged above the pile body test sample, a cross beam is arranged on the upper portion of the fixed support, the cross beam comprises a triangular support fixed on the fixed support and a trapezoidal stress dispersion cushion block arranged between the load sensor and the triangular support, and a displacement sensor fixed on the loading device and used for monitoring deformation of the cross beam is arranged above the triangular support.
The beneficial effects of adopting above-mentioned technical scheme to produce lie in:
(1) The conical pile body is artificially divided into a frozen-pulled area and a non-frozen-pulled area, and the tangential frozen expansion force of the frozen-pulled area is obtained by measuring the frozen-pulled area, so that the error caused by temperature compensation when the strain gauge is adopted for measurement is avoided. According to the test method, the area which does not need to be tested for the frost-drawing force is protected through Vaseline and felt paper, the frost-drawing force of the unprotected area is tested through the existing test device, the tangential frost-heaving force of the area is obtained, and the tangential frost-heaving force of all the areas can be tested through repeated operation. The method is different from the prior method in that the sample does not contain steel bars, temperature compensation is not needed, the distribution condition of tangential frost heaving force along the pile body can be measured, and a basis is provided for the design of the tapered pile.
(2) The invention obtains the microscopic physical quantity by measuring the macroscopic physical quantity, so that the difference of the frozen pulling conditions of different areas can be obviously observed in the test process.
(3) The invention is suitable for testing tangential frost heaving force distribution of the model pile foundation in an indoor test and an in-situ test.
Drawings
FIG. 1 is a flow chart of a method for measuring tangential frost heaving force distribution of a tapered pile;
FIG. 2 is a schematic diagram of a pile body pulling resistance test device;
FIG. 3 is a side view of a tapered pile sample according to example 1 of the present invention;
FIG. 4 is a side view of the tapered pile sample of example 1 of the present invention for measuring the tangential frost heaving force in zone I;
FIG. 5 is a side view of the tapered pile sample of example 1 of the present invention measuring II region tangential frost heaving force;
FIG. 6 is a side view of a tapered pile sample of example 1 of the present invention measuring the tangential frost heaving force in zone III;
FIG. 7 is a schematic illustration of the present pile test specimen;
wherein, 2-1, fixing the bracket; 2-2, a cross beam; 2-3, a displacement sensor; 2-4, a load sensor; 2-5 parts of temperature sensor, 2-6 parts of sample tube, 2-7 parts of refrigerating fluid circulation tube, 2-8 parts of moisture sensor, 2-9 parts of pile body sample, 2-10 parts of light polyurethane foam; 3-1, a conical pile sample; 3-2, grooves; 4-1, felt paper; 4-2, felt paper allowance; 4-3, freezing and pulling areas; 4-4, cold-resistant ribbon; 4-5, non-frozen pulling area.
Detailed Description
In order to make the above objects, features and advantages of the present invention more comprehensible, embodiments accompanied with figures and detailed description of embodiments of the present invention are described in detail below, wherein it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention provides a new thought for tangential frost heaving force distribution test, which is characterized in that microscopic physical quantity is calculated and deduced by measuring macroscopic physical quantity, so that errors caused by external conditions such as temperature and the like when the microscopic physical quantity is directly measured are avoided. The pile body anti-pulling performance test device is based on the existing device, and is shown in figure 2, for example, patent application number is 2015102967574, and the name is the pile body anti-pulling performance test device and the experimental method thereof.
The pile body anti-freezing performance test device comprises a specific conical pile body sample and an improved novel pile body anti-freezing performance test device. The improved pile body anti-freeze-pull performance test device comprises an original pile body anti-freeze-pull performance test device (the upper cold bath plate part is removed), various sensors and a displacement constraint reinforcing device, wherein the displacement constraint reinforcing device is a stainless steel beam welded with a trapezoidal stress dispersion cushion block and a triangular bracket. When the frozen pulling force is measured, a trapezoidal stress dispersion cushion block and a cross beam of the triangular bracket are additionally arranged, and a displacement sensor for monitoring the deformation of the cross beam is additionally arranged; when the measurement of the frost-drawing displacement is carried out, the displacement sensor is directly arranged at the pile top to measure the frost-drawing displacement of the pile body.
The method comprises the following steps: referring to fig. 1, the device comprises a sample tube 2-6, a fixed bracket 2-1 for fixing the sample tube 2-6 and a base positioned at the lower part of a pile body sample 2-9 in the sample tube 2-6, wherein a refrigerating fluid circulating tube 2-7 is arranged below the sample tube 2-6, except that a water sensor 2-8 is arranged at one side on the inner wall of the sample tube 2-6, and a temperature sensor 2-5 is arranged at the other side; the pile body test sample 2-9 is provided with a load sensor 2-4 above, the upper part of the fixed support is provided with a cross beam 2-2 (also called a constraint displacement reinforcing device which comprises a triangular support and a trapezoidal stress dispersion cushion block), the cross beam 2-2 comprises the triangular support fixed on the fixed support 2-1 and the trapezoidal stress dispersion cushion block arranged between the load sensor 2-4 and the triangular support, and the upper part of the triangular support is provided with a displacement sensor 2-3 fixed on a loading device and used for monitoring the deformation of the cross beam.
Referring to fig. 7, the pile body sample 2-9 has a height of 25-35 cm, a small circular diameter of 2-8 cm, and a cone angle of 0-11 degrees, and the pile body volume is required to be modified under the condition of ensuring that the pile body side surface area is unchanged in order to ensure the cone angle as a single variable. 2-10 parts of light polyurethane foam are arranged in the pile body sample. The pile body sample is adopted to carry out a tangential frost heaving force distribution test, as shown in a flow chart shown in fig. 1, wherein the cycle number N is determined according to the lengths of the pile body and the divided areas, and the specific steps are as follows:
the first step: preparing a pile body sample; in order to approximate the density of reinforced concrete piles in the site, aluminum alloy is adopted as the raw material of the pile body, the total length of the pile body is 25-35 cm, the diameter of the pile is 3-8 cm, a circular groove which surrounds the pile is required to be arranged at intervals along the direction of the pile body so as to conveniently bind felt paper, as shown in figure 3, the depth of the circular groove is 2-3 mm, the width of the circular groove is 2-4 mm, and the distance between two adjacent grooves is 3-6 cm; the groove distance is determined according to the test precision, and the groove distance is too small and high in precision, but the workload is large; the groove distance is too large, the precision is low, but the workload is small;
and a second step of: anti-freezing and pulling treatment of a conical pile part area; the method comprises the steps of (1) keeping an area needing to measure the freeze-pulling force in an original state, carrying out freeze-pulling treatment on other areas, firstly coating vaseline on the freeze-pulling area, uniformly coating vaseline on two sides of felt paper, finally wrapping the treated felt paper on the area coated with the vaseline, binding and fixing, wherein the felt paper is required to be covered on the area needing to be protected in a flat way, a margin of 1-2 cm is reserved at the lower end of the felt paper, and the margin is folded for several times and bound in a groove as shown in fig. 4;
and a third step of: pile body is embedded in test soil sample: placing the pile body in an experimental device, and finally uniformly placing and compacting a soil sample around the pile, wherein the soil sample adopts frost heaving sensitive soil, the compaction degree is 93% -97%, layered compaction is required, a temperature sensor is required to be arranged every 5-6 cm in the process of embedding the soil sample, and a moisture sensor is required to be arranged every 10cm for 2-8;
fourth step: measurement of the freeze-pull force in the unidirectional freezing process: ensuring unidirectional freezing of a pile body anti-pulling performance test device, measuring the freezing pulling force by adopting a cross beam 2-2 and a load sensor 2-4, arranging a displacement sensor 2-3 on a reaction frame to monitor the displacement condition of the reaction frame, ensuring the bottom temperature of the pile body to be constant at 1 degree through a refrigerating fluid circulating pipe 2-7 in the unidirectional freezing process so as to eliminate the influence of normal frost heaving force, wrapping the periphery of a sample barrel by adopting heat preservation cotton, putting the whole experimental device in a high-temperature and low-temperature alternating freezing-thawing circulating box, and adjusting the temperature to be-20 degrees for low-temperature freezing;
fifth step: calculating average tangential frost heaving force; the frost-drawing force is obtained according to the load sensor, and then the total tangential frost-expansion force and the area of the frost-drawing area are calculated, and the average tangential frost-expansion force is calculated according to the ratio of the total tangential frost-expansion force and the area of the frost-drawing area, wherein the formula is as follows:
wherein τ i Average tangential frost heave force (in MPa) for the i-th zone; g is the total weight of the pile body (unit is N); t is the frozen pulling force (unit is N) measured by the existing experimental device; s is S i Is the side surface area of the ith zone (in mm 2 )。
The data obtained are the average tangential frost heaving force of the unprotected region.
Sixth step: the average tangential frost heaving force was determined for all areas: cleaning vaseline on the surface of the sample, and repeating the steps from the second step to the fifth step until the average tangential frost heaving force of all the areas is measured. Through the test process, the macroscopic physical quantity is measured in the different regions, and then the microscopic physical quantity is calculated and deduced, so that errors caused by external conditions such as temperature and the like when the microscopic physical quantity is directly measured are avoided, and the difference of the freezing and drawing conditions of different regions can be obviously observed in the test process.
Example 1:
the first step: preparing a pile body sample: in order to approximate the density of reinforced concrete piles in the field, aluminum alloy is adopted as the raw material of the pile body, the total length of the pile body is 30cm, the pile diameter is 6cm, a circular groove for winding the pile is arranged at intervals along the direction of the pile body so as to conveniently bind felt paper, as shown in figure 3, the depth of the circular groove 3-2 is 2mm, the width is 3mm, and the distance between two adjacent grooves is 6cm.
And a second step of: and (3) anti-freezing and anti-pulling treatment of a pile body part area: as shown in fig. 4, vaseline is smeared on the areas from II to V4-5, the area 4-3 is not treated, vaseline is smeared on the two sides of the felt paper 4-1 uniformly, the treated felt paper is wrapped on the areas from II to V smoothly, finally the upper end of the area II and the lower end of the area V are fixed by binding 4-4 with cold-resistant binding tapes, the rest 4-2 of 2cm felt paper is reserved at the tail end of the area V, and the rest is folded several times and bound in the grooves.
And a third step of: pile body is embedded in test soil sample: placing the pile body in an experimental device 2-1, uniformly placing and compacting a soil sample around the pile, wherein the soil sample adopts frost heaving sensitive soil, the compaction degree is 95%, layered compaction is required, a temperature sensor 2-3 is required to be arranged every 5cm in the process of embedding the soil sample, and a moisture sensor 2-8 is required to be arranged every 10 cm;
fifth step: measurement of the freeze-pull force in the unidirectional freezing process: ensuring unidirectional freezing of the test device, measuring the freezing and pulling force by adopting a counter-force steel frame and a load sensor 2-2, ensuring the bottom temperature of the pile body to be constant at 1 ℃ through a refrigerating fluid circulating pipe 2-7 in the unidirectional freezing process so as to eliminate the influence of normal frost heaving force, wrapping the periphery of a sample barrel by adopting heat-insulating cotton, putting the whole test device into a high-low temperature alternating freezing and thawing circulating box, and regulating the temperature to be minus 20 ℃ for low-temperature freezing;
sixth step: calculation of average tangential frost heaving force: the frost-drawing force is obtained according to the load sensor, and then the total tangential frost-expansion force and the area of the frost-drawing area are calculated, and the average tangential frost-expansion force is calculated according to the ratio of the total tangential frost-expansion force and the area of the frost-drawing area, wherein the formula is as follows:
wherein τ i Is the ith regionIs a mean tangential frost heaving force; g is the total weight of the tapered pile; t is the frozen pulling force measured by the existing test device; s is S i Is the side surface area of the i-th region.
The obtained data is the average tangential frost heaving force of the area I
Sixth step: the average tangential frost heaving force was determined for all areas: firstly cleaning vaseline on the surface of a sample, then smearing the vaseline on the area I and the area III to the area V, smearing the vaseline on the front and back sides of felt paper, then covering the area I and the area III to the area V, finally binding and fixing, and leaving 2cm of allowance at the lower end of the covered area, as shown in figure 5. Repeating the steps from the fourth step to the sixth step, wherein the obtained data is the average tangential frost heaving force of the II area. And repeating the process, and respectively measuring the average tangential frost heaving force of the III region, the IV region and the V region. And analyzing tangential frost heaving force of all areas to obtain the rule that the tangential frost heaving force is distributed along with the pile body of the conical pile.
The invention mainly solves the problem that in the indoor test, the tangential frost heave force distribution cannot be measured by adopting a strain gauge for the small-sized conical pile model. The test method for measuring the average tangential frost heaving force of the conical pile in the divided areas adopted by the test can avoid the influence of temperature on the conventional strain gauge method, can more clearly observe the influence of the tangential frost heaving force of a certain area on the frost heaving of the pile, and is more beneficial to researching the distribution situation of the tangential frost heaving force along the pile side.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (9)
1. A method for testing the tangential frost heaving force distribution of a conical pile in a frozen soil area in a test room is characterized by comprising the following steps: which comprises the following steps:
1) Preparing a pile body sample: in order to approximate the density of the reinforced concrete pile on site, aluminum alloy is used as a raw material for preparing a pile body, and circular grooves which wind the pile are carved every 3 cm to 6cm along the direction of the pile body;
2) Anti-freezing and pulling treatment of a pile body partial area; the area needing to measure the freeze-pulling force is kept as it is, and other areas are subjected to freeze-pulling treatment;
3) Conical piles are embedded in the test soil samples: placing the pile body in a pile body anti-pulling performance test device, uniformly placing soil samples around the pile body, and compacting in layers;
4) Measurement of the freeze-pull force in the unidirectional freezing process: the pile body pulling resistance test device is ensured to be frozen unidirectionally from the pile top to the pile bottom, and the pulling force is measured by adopting a counterforce steel frame and a load sensor;
5) Average tangential frost heaving force calculation: calculating the total tangential frost heaving force and the curved surface area of the frost heaving region, and calculating the average tangential frost heaving force according to the ratio of the total tangential frost heaving force and the curved surface area of the frost heaving region;
the formula is as follows:
wherein,,τ i is the firstiAverage tangential frost heaving force of the region in MPa;Gthe unit is N, which is the total weight of the pile body;Tthe unit of the frozen pulling force is N, which is measured by the existing experimental device;S i is the firstiThe side surface area of the region is in mm 2 ；
6) The average tangential frost heaving force was determined for all areas: repeating the second to fifth steps until the average tangential frost heaving force of all the areas is measured.
2. The method for testing the tangential frost heaving force distribution of the conical pile in the frozen soil area, according to claim 1, is characterized in that: the total length of the pile body in the step 1) is 25-35 cm, the small circular diameter is 3-8 cm, and the cone angle of the conical pile is 3-11 degrees.
3. The method for testing the tangential frost heaving force distribution of the conical pile in the frozen soil area, according to claim 1, is characterized in that: the depth of the circular groove of the pile body in the step 1) is 2-3 mm, the width is 2-4 mm, and the distance between two adjacent grooves is 3-6 cm.
4. The method for testing the tangential frost heaving force distribution of the conical pile in the frozen soil area, according to claim 1, is characterized in that: the anti-freezing measure in the step 2) is to coat vaseline on the anti-freezing area, and then wrap felt paper on the area coated with the vaseline and bind and fix the felt paper.
5. The method for testing the tangential frost heaving force distribution of the conical pile in the frozen soil area, according to claim 1, is characterized in that: the soil sample in the step 3) adopts frost heave sensitive soil, the compactness is 93% -97%, layered compaction is needed, a temperature sensor is needed to be arranged every 5-6 cm in the process of embedding the soil sample, and a moisture sensor is needed to be arranged every 10 cm.
6. The method for testing the tangential frost heaving force distribution of the conical pile in the frozen soil area, according to claim 1, is characterized in that: in the step 4), the constant temperature of the bottom of the pile body is ensured to be 1 ℃ in the unidirectional freezing process, the influence of normal frost heaving force is eliminated, and the load sensor and the temperature sensor adopt DT80 data acquisition devices for data acquisition.
7. The method for testing the tangential frost heaving force distribution of the conical pile in the frozen soil area, according to claim 1, is characterized in that: in the repeated test process of the step 6), the vaseline on the surface of the sample is required to be cleaned up and then the step 2) is carried out.
8. The method for testing the tangential frost heaving force distribution of the conical pile in the frozen soil area according to claim 4, wherein the method comprises the following steps: when the felt paper is subjected to anti-freezing and anti-drawing treatment, the upper end and the lower end of the felt paper are positioned in the grooves, the lower end of the felt paper is ensured to leave 1-2 cm of allowance in the grooves, and the allowance is folded for several times and bound in the grooves; before the felt paper is wrapped, vaseline is coated on the front and back sides of the felt paper; in order to ensure unidirectional freezing, thermal insulation cotton is adopted to perform thermal insulation treatment on the periphery of the pile body anti-pulling performance test device, and the pile body anti-pulling performance test device is placed in a high-low temperature alternating freezing and thawing circulation box.
9. The method for testing the tangential frost heaving force distribution of the conical pile in the frozen soil area in the test room is characterized by comprising the following steps of: pile body resistance to plucking capability test device who uses in the test method, it includes sample tube (2-6), is used for fixed support (2-1) of sample tube (2-6) and is located the base of the pile body sample lower part in sample tube (2-6), sample tube (2-6) below is equipped with freezing liquid circulating pipe (2-7), its characterized in that: a water sensor (2-8) is arranged on one side of the inner wall of the sample tube, and a temperature sensor (2-5) is arranged on the other side of the inner wall of the sample tube; the pile body test sample (2-9) is provided with a load sensor (2-4) above, the upper part of the fixed support is provided with a cross beam, the cross beam comprises a triangular support fixed on the fixed support and a trapezoidal stress dispersion cushion block (2-2) arranged between the load sensor (2-4) and the triangular support, and a displacement sensor (2-3) fixed on the loading device and used for monitoring the deformation of the cross beam is arranged above the triangular support.
Priority Applications (1)
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| CN109783938B (en) * | 2019-01-16 | 2021-05-14 | 中国科学院西北生态环境资源研究院 | Anti-freezing extraction checking calculation method and device |
| CN109931861B (en) * | 2019-03-04 | 2024-01-30 | 中建东设岩土工程有限公司 | Soil frost heaving force testing method and device |
| CN112064627A (en) * | 2019-06-10 | 2020-12-11 | 中国科学院寒区旱区环境与工程研究所 | Freeze-proofing taper cylinder pile foundation in frozen soil area and construction process thereof |
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