System and method for testing in-situ loess collapsibility coefficient

Abstract

This invention discloses a system and method for testing the collapsibility coefficient of undisturbed loess. The system includes a constant-force jacking device, a humidification and maintenance device, and a collapsibility coefficient determination device. The constant-force jacking device is installed at the annular soil mass within the test hole to apply a constant horizontal jacking force to the annular soil mass. The humidification and maintenance device covers the outside of the annular soil mass to gradually humidify it and obtain its moisture content. The collapsibility coefficient determination device is connected to the constant-force jacking device and the humidification and maintenance device to determine the collapsibility coefficient or self-weight collapsibility coefficient of the annular soil mass at different moisture contents based on the jacking distance of the constant-force jacking device. This invention utilizes undisturbed annular loess in the field, eliminating the need for sampling and indoor testing to obtain the collapsibility coefficient or self-weight collapsibility coefficient. It preserves the original structure of the loess, resulting in more accurate collapsibility test results that meet the needs of engineering design and disaster management.

Description

Technical Field

[0001] This invention discloses a system and method for testing the collapsibility coefficient of undisturbed loess, belonging to the field of collapsibility coefficient testing technology. Background Technology

[0002] Collapsibility is one of the most unique engineering properties of loess. Making an objective evaluation of the collapsibility of loess is the core of engineering investigation and the basis of design in collapsible loess areas.

[0003] Current methods for obtaining loess collapsibility mainly rely on field sampling and indoor determination using a uniaxial compression apparatus. However, loess has unique properties, characterized by its loose structure. Sampling can disrupt its structure, leading to a significant discrepancy between the collapsibility coefficient determined by indoor testing and the actual value, making it difficult to reflect the true collapsibility of loess. Summary of the Invention

[0004] The purpose of this application is to provide a system and method for testing the collapsibility coefficient of undisturbed loess, so as to solve the technical problem that the collapsibility coefficient of loess obtained by the existing technology using a uniaxial compressor indoors is inaccurate.

[0005] The first aspect of the present invention provides a system for testing the collapsibility coefficient of undisturbed loess, including a constant force jacking device, a humidification and maintenance device, and a collapsibility coefficient determination device;

[0006] The constant force jacking device is installed in the annular soil body inside the test hole to apply a constant horizontal jacking force to the annular soil body.

[0007] The humidification and retention device is wrapped around the outside of the annular soil body and is used to gradually humidify the annular soil body and obtain the water content of the annular soil body;

[0008] The collapsibility coefficient determining device is connected to the constant force jacking device and the humidification and maintenance device, and is used to determine the collapsibility coefficient or self-weight collapsibility coefficient of the annular soil under different moisture contents based on the jacking distance of the constant force jacking device.

[0009] Preferably, the humidification and retention device includes a housing, a humidification unit, and a moisture content acquisition unit;

[0010] The shell covers the outside of the annular soil body;

[0011] The humidification unit passes through the shell and is located on the upper surface of the annular soil body, and is used to gradually humidify the annular soil body;

[0012] The moisture content acquisition unit is fixedly installed inside the shell and connected to the collapsibility coefficient determination device, and is used to transmit the acquired moisture content of the annular soil to the collapsibility coefficient determination device.

[0013] Preferably, the humidification unit includes multiple humidification tubes;

[0014] The multiple humidification pipes are arranged in parallel on the upper surface of the annular soil body;

[0015] Each of the humidifying tubes has multiple humidifying holes on its tube body.

[0016] Preferably, the humidification unit further includes a plurality of atomizing nozzles corresponding to the number of humidification holes;

[0017] One of the atomizing nozzles is disposed on one of the humidification holes.

[0018] Preferably, the humidification and retention device further includes a water-proof tank;

[0019] The water-proof groove is disposed inside the shell and is in contact with the lower surface of the annular soil body.

[0020] Preferably, the constant force jacking device includes a jacking structure and a jacking plate;

[0021] The jacking end of the jacking structure is connected to one side surface of the jacking plate;

[0022] The other side surface of the jacking plate is in contact with the first sidewall of the annular soil mass.

[0023] Preferably, the constant force jacking device further includes a baffle;

[0024] One side surface of the baffle is connected to the bottom end of the jacking structure, and the other side surface is in contact with the second sidewall of the annular soil.

[0025] The second sidewall is disposed opposite to the first sidewall.

[0026] Preferably, the device for determining the sinkhole coefficient includes a data acquisition unit and a processing unit connected to the data acquisition unit;

[0027] The acquisition unit is connected to the constant force jacking device and is used to acquire the first jacking distance and the second jacking distance of the constant force jacking device.

[0028] The processing unit is used to determine the collapsibility coefficient or self-weight collapsibility coefficient of the annular soil body under different moisture contents based on the initial ring width, the first jacking distance and the second jacking distance of the annular soil body.

[0029] The first jacking distance is the jacking distance of the constant force jacking device over the unmoisturized annular soil body;

[0030] The second jacking distance is the jacking distance of the constant force jacking device for the annular soil with different water contents.

[0031] Preferably, the device for determining the collapsibility coefficient further includes a display unit;

[0032] The display unit is connected to the processing unit and is used to display the collapsibility coefficient or self-weight collapsibility coefficient of the annular soil.

[0033] A second aspect of the present invention provides a method for testing the collapsibility coefficient of undisturbed loess using the above-mentioned undisturbed loess collapsibility coefficient testing system, comprising:

[0034] Obtain the first jacking distance when the constant force jacking device applies a constant jacking force to the annular soil mass;

[0035] The annular soil is gradually moistened by a humidification and maintenance device, and the second jacking distance is obtained when a constant jacking force is applied to the annular soil with different water contents by a constant force jacking device.

[0036] The collapse coefficient or self-weight collapse coefficient of the annular soil is determined based on the initial ring width, the first jacking distance, and the second jacking distance.

[0037] The original loess collapsibility coefficient testing system and method of the present invention have the following advantages compared with the prior art:

[0038] This invention uses undisturbed loess in a ring shape on site, eliminating the need for sampling and indoor testing to obtain the collapsibility coefficient or self-weight collapsibility coefficient. This preserves the original structure of the loess, making the collapsibility test results more accurate and meeting the needs of engineering design and disaster management.

[0039] This invention utilizes a humidification and retention device to gradually humidify annular soil and obtain the water content of the annular soil. Therefore, when determining the collapsibility coefficient, it can obtain all the collapsibility coefficients or self-weight collapsibility coefficients of loess under pressure due to different water contents, rather than just the collapsibility coefficients or self-weight collapsibility coefficients under saturation. The results obtained are more comprehensive and more accurate. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the original loess collapsibility coefficient testing system in an embodiment of the present invention.

[0041] List of components and reference numerals:

[0042] 1 is a constant force jacking device; 11 is a jacking structure; 12 is a jacking plate; 13 is a baffle; 2 is a humidification and maintenance device; 21 is a shell; 22 is a humidification unit; 221 is a humidification pipe; 222 is an atomizing nozzle; 23 is a water-blocking groove; 3 is a device for determining the collapse coefficient; 4 is a test hole; 5 is a ring-shaped soil body; 6 is a hole enlargement. Detailed Implementation

[0043] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0044] The first aspect of the present invention provides a system for testing the collapsibility coefficient of undisturbed loess, such as... Figure 1 As shown, it includes a constant force jacking device 1, a humidification and holding device 2, and a wet collapse coefficient determination device 3;

[0045] The constant force jacking device 1 is installed in the annular soil body 5 inside the test hole 4, and is used to apply a constant jacking force in the horizontal direction to the annular soil body 5.

[0046] The humidification and retention device 2 is wrapped around the outside of the annular soil body 5 to gradually humidify the annular soil body 5 and obtain the water content of the annular soil body 5.

[0047] The collapsibility coefficient determining device 3 is connected to the constant force jacking device 1 and the humidification and maintenance device 2, and is used to determine the collapsibility coefficient or self-weight collapsibility coefficient of the annular soil 5 under different moisture contents based on the jacking distance of the constant force jacking device 1.

[0048] In this embodiment of the invention, the method for obtaining the annular soil body 5 is as follows: the hole is enlarged within a preset range above and below the preset elevation in the test hole 4 to obtain the annular soil body 5 and the enlarged holes 6 located above and below it.

[0049] The preset range is more than half the height of the ring-shaped soil body 5. For example, if the height of the ring-shaped soil body 5 is h, then the preset range is more than h / 2.

[0050] In this embodiment of the invention, the test hole 4 can be a newly drilled hole or an exploration hole. Since an exploration hole can be used, one hole can be used for multiple purposes, reducing the workload of testing and saving time and effort.

[0051] This invention utilizes undisturbed, ring-shaped loess from the field, eliminating the need for sampling and indoor testing to obtain the collapsibility coefficient or self-weight collapsibility coefficient. This preserves the original structure of the loess, making the collapsibility test results more accurate and meeting the needs of engineering design and disaster management.

[0052] This invention utilizes a humidification and retention device 2 to gradually humidify the annular soil mass 5 and obtains its water content. Therefore, when determining the collapsibility coefficient or self-weight collapsibility coefficient, it can obtain all collapsibility coefficients or self-weight collapsibility coefficients of loess under pressure due to different water contents, rather than just the collapsibility coefficient or self-weight collapsibility coefficient under saturation, resulting in a more comprehensive and accurate result. Of course, this invention can also, depending on the testing requirements, only obtain the collapsibility coefficient or self-weight collapsibility coefficient under saturation.

[0053] To achieve humidification and moisture retention of the annular soil 5 and avoid the influence of the on-site environment on the accuracy of the test results, the humidification and retention device 2 of this embodiment includes a shell 21, a humidification unit 22 and a moisture content acquisition unit (not shown in the figure).

[0054] The shell 21 covers the outside of the annular soil body 5;

[0055] The humidification unit 22 passes through the shell 21 and is located on the upper surface of the annular soil 5, and is used to gradually humidify the annular soil 5.

[0056] The moisture content acquisition unit is fixedly installed inside the shell 21 and connected to the collapsibility coefficient determination device 3, which is used to transfer the acquired moisture content of the annular soil 5 to the collapsibility coefficient determination device 3.

[0057] The shell 21 of the present invention may cover only the test portion of the annular soil 5, or it may cover the entire annular soil 5.

[0058] The moisture content acquisition unit of the present invention can specifically be a soil moisture content sensor. The soil moisture content sensor emits electromagnetic waves of a certain frequency. The electromagnetic waves are transmitted along the probe, return after reaching the bottom, and the voltage output by the probe is detected. Since the change of soil dielectric constant usually depends on soil moisture content, the soil moisture content can be calculated from the relationship between output voltage and moisture content.

[0059] To further simulate a natural rainfall environment, the humidification unit 22 in this embodiment of the invention includes multiple humidification tubes 221;

[0060] Multiple humidification pipes 221 are arranged in parallel on the upper surface of the annular soil body 5;

[0061] Each humidification tube 221 has multiple humidification holes on its body.

[0062] The present invention achieves uniform and gradual humidification by using multiple humidification pipes 221 arranged in parallel and multiple humidification holes opened on each humidification pipe 221, avoiding the impact of water erosion on the annular soil body 5, thereby more realistically simulating the environment of deep loess, and making the obtained collapsibility coefficient or self-weight collapsibility coefficient more accurate.

[0063] To further avoid the impact of water erosion on the annular soil 5, the humidification unit 22 of the present invention also includes a plurality of atomizing nozzles 222 corresponding to the number of humidification holes; one atomizing nozzle 222 is disposed on one humidification hole, thereby achieving more uniform and gentler humidification.

[0064] The humidification and retention device 2 of this embodiment of the invention also includes a water-proof tank 23;

[0065] The water-blocking groove 23 is set inside the shell 21 and is in contact with the lower surface of the annular soil 5.

[0066] In this embodiment of the invention, a water-proof trough 23 is used to prevent water from flowing out. Combined with the shell 21 and the humidification unit 22, the moisture content of the annular soil 5 is guaranteed, so that the tested collapsibility coefficient or self-weight collapsibility coefficient is more accurate.

[0067] The constant force jacking device 1 of this embodiment of the invention includes a jacking structure 11 and a jacking plate 12;

[0068] In this embodiment, the jacking end of the jacking structure 11 is connected to one side surface of the jacking plate 12, and the other side surface of the jacking plate 12 is in contact with the first side wall of the annular soil body 5. This embodiment uses the jacking plate 12 to apply force to the first side wall of the annular soil body 5, increasing the force application surface and achieving a uniform force application effect, thus avoiding damage to the annular soil body 5 structure caused by single-point force application.

[0069] Furthermore, the jacking plate 12 of the present invention has an arc-shaped structure, and its curvature is the same as that of the first side wall of the annular soil body 5, thereby ensuring that the annular soil body 5 is subjected to uniform force as a whole.

[0070] The constant force jacking device 1 of this embodiment of the invention also includes a baffle 13;

[0071] One side surface of the baffle 13 is connected to the bottom end of the jacking structure 11, and the other side surface is connected to the second side wall of the annular soil 5; the second side wall is arranged opposite to the first side wall.

[0072] The purpose of setting the baffle 13 in this embodiment of the invention is to provide a stable jacking force for the jacking structure 11.

[0073] Furthermore, in order to avoid damaging the second sidewall at the baffle 13, the baffle 13 in this embodiment of the invention has an arc-shaped structure, and its curvature is the same as that of the second sidewall.

[0074] The sinkhole coefficient determination device 3 in this embodiment of the invention includes a data acquisition unit and a processing unit connected to the data acquisition unit;

[0075] The data acquisition unit is connected to the constant force jacking device 1 and is used to acquire the first jacking distance and the second jacking distance of the constant force jacking device 1.

[0076] The processing unit is used to determine the collapsibility coefficient or self-weight collapsibility coefficient of the annular soil 5 under different water contents based on the initial ring width, the first jacking distance and the second jacking distance of the annular soil 5.

[0077] The first jacking distance is the jacking distance of the constant force jacking device 1 on the unmoisturized annular soil 5. When measuring the self-weight collapse coefficient, it is specifically: using the constant force jacking device 1 to apply a constant horizontal jacking force to the unmoisturized annular soil 5 until the unmoisturized annular soil 5 stabilizes, the jacking distance of the constant force jacking device 1 is then measured. When measuring the collapse coefficient, it is specifically: using the constant force jacking device 1 to apply a preset level of constant jacking force to the unmoisturized annular soil 5 step by step until a specified level of constant horizontal jacking force is applied, and the jacking distance of the constant force jacking device 1 is measured after the unmoisturized annular soil 5 stabilizes.

[0078] The second jacking distance is the jacking distance of the constant force jacking device 1 for the annular soil body 5 with different water contents. Specifically, the constant force jacking device 1 applies a constant horizontal jacking force to the annular soil body 5 with a determined water content until the annular soil body 5 stabilizes. The jacking distance of the constant force jacking device 1 after that is the jacking distance. If you want to obtain the collapsibility coefficient or self-weight collapsibility coefficient of the annular soil body 5 with a further increased water content, you continue to apply a constant horizontal jacking force to the annular soil body 5 with an increased water content until the annular soil body 5 stabilizes. Repeat this step to obtain the jacking distance of the annular soil body 5 with different water contents.

[0079] The sinkhole coefficient determination device 3 of this embodiment of the invention also includes a display unit;

[0080] The display unit is connected to the processing unit and is used to display the collapsibility coefficient or self-weight collapsibility coefficient of the annular soil 5.

[0081] The purpose of setting up a display unit in this embodiment of the invention is to allow for intuitive observation of the collapsibility coefficient or self-weight collapsibility coefficient of the annular soil body 5.

[0082] The testing system of this invention has a simple structure and can measure the collapsibility coefficient or self-weight collapsibility coefficient of undisturbed loess at different moisture contents in the surface and deep layers. The results obtained are highly accurate and more comprehensive.

[0083] A second aspect of the present invention provides a method for testing the collapsibility coefficient of undisturbed loess using the above-mentioned undisturbed loess collapsibility coefficient testing system, comprising:

[0084] Step 1: Obtain the first jacking distance when the constant force jacking device applies a constant jacking force to the annular soil mass;

[0085] Step 2: Gradually humidify the annular soil using a humidification and maintenance device, and obtain the second jacking distance when the constant force jacking device applies a constant jacking force to the annular soil with different water contents;

[0086] Step 3: Based on the initial ring width, first jacking distance, and second jacking distance of the annular soil, determine the collapsibility coefficient or self-weight collapsibility coefficient of the annular soil with different water contents, and obtain multiple collapsibility coefficients or self-weight collapsibility coefficients.

[0087] For example, when measuring the self-weight collapsibility coefficient using the above-mentioned undisturbed loess collapsibility coefficient testing system, the specific method is as follows:

[0088] Step 1: Apply a preset constant jacking force to the annular soil body 5 under natural humidity, and obtain the first jacking distance when the constant force jacking device applies a constant jacking force to the annular soil body after the deformation of the annular soil body 5 stabilizes.

[0089] Step 2: Gradually humidify the annular soil 5 using a humidification and maintenance device. After humidification, apply a constant jacking force continuously and record the deformation reading every preset time until the deformation stabilizes, thereby obtaining the second jacking distance under different moisture contents.

[0090] Step 3: Determine the self-weight collapsibility coefficient of the annular soil with different water contents based on the initial ring width, the first jacking distance, and the second jacking distance.

[0091] For example, the self-weight collapsibility coefficient of the annular soil 5 is determined according to formula (1):

[0092]

[0093] In the formula, δ s h is the self-weight collapsibility coefficient of the annular soil mass 5; h0 is the initial ring width of the annular soil mass; h p To maintain the natural moisture content (natural humidity) and structure of the ring-shaped soil 5, the ring width after stabilization under a constant jacking force is determined based on the difference between the initial ring width and the first jacking distance; h p ′ is the ring width of the ring soil 5 after stabilization under constant jacking force and water content. It is determined based on the difference between the initial ring width and the first jacking distance and the second jacking distance.

[0094] The method for testing the collapsibility coefficient of undisturbed loess using the above-mentioned undisturbed loess collapsibility coefficient testing system is as follows: When measuring the collapsibility coefficient, the specific steps are as follows:

[0095] Step 1: Determine the progressively increasing constant jacking forces applied by the constant force jacking module based on project requirements and loess deposition conditions. After the annular soil 5 stabilizes under the first constant jacking force, apply the second constant jacking force, and so on, until the annular soil 5 deforms and stabilizes under the specified level of constant jacking force. Obtain the first jacking distance when the constant force jacking device applies a constant jacking force to the annular soil 5.

[0096] Step 2: According to the engineering conditions, immerse the annular soil 5 in water. At the determined water content, apply the next level of constant jacking force to the annular soil 5, and record the deformation reading every preset time until the deformation stabilizes. Determine the collapsibility coefficient of the annular soil 5 according to formula (2):

[0097]

[0098] In the formula, δ m h0 is the collapsibility coefficient of the annular soil body 5; h1 is the initial ring width of the annular soil body 5 after stabilization under a specified level of constant jacking force, which is determined based on the difference between the initial ring width and the first jacking distance; h2 is the ring width of the annular soil body 5 after stabilization of collapsibility deformation at a certain moisture content under the next level of constant jacking force, which is determined based on the difference between the initial ring width and the first and second jacking distances.

[0099] The original loess collapsibility coefficient test method of the present invention has the advantages of being simple, easy to operate, highly accurate, and providing a more comprehensive collapsibility coefficient and self-weight collapsibility coefficient, which can meet the needs of engineering design and disaster management.

[0100] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A system for testing the collapsibility coefficient of undisturbed loess, characterized in that, Includes a constant force jacking device, a humidification and retention device, and a device for determining the wet collapse coefficient; The constant force jacking device is installed in the annular soil body inside the test hole to apply a constant horizontal jacking force to the annular soil body. The humidification and retention device is wrapped around the outside of the annular soil body and is used to gradually humidify the annular soil body and obtain the water content of the annular soil body; The collapsibility coefficient determining device is connected to the constant force jacking device and the humidification and maintenance device, and is used to determine the collapsibility coefficient or self-weight collapsibility coefficient of the annular soil under different moisture contents based on the jacking distance of the constant force jacking device. The humidification and retention device includes a housing, a humidification unit, and a moisture content acquisition unit; The shell covers the outside of the annular soil body; The humidification unit passes through the shell and is located on the upper surface of the annular soil body, and is used to gradually humidify the annular soil body; The moisture content acquisition unit is fixedly installed inside the shell and connected to the collapsibility coefficient determination device, and is used to transmit the acquired moisture content of the annular soil to the collapsibility coefficient determination device. The constant force jacking device includes a jacking structure and a jacking plate; The jacking end of the jacking structure is connected to one side surface of the jacking plate; The other side surface of the jacking plate is in contact with the first side wall of the annular soil mass; The device for determining the collapsibility coefficient includes a data acquisition unit and a processing unit connected to the data acquisition unit; The acquisition unit is connected to the constant force jacking device and is used to acquire the first jacking distance and the second jacking distance of the constant force jacking device. The processing unit is used to determine the collapsibility coefficient or self-weight collapsibility coefficient of the annular soil body under different moisture contents based on the initial ring width, the first jacking distance and the second jacking distance of the annular soil body. The first jacking distance is the jacking distance of the constant force jacking device over the unmoisturized annular soil body; The second jacking distance is the jacking distance of the constant force jacking device for the annular soil with different water contents.

2. The original loess collapsibility coefficient testing system according to claim 1, characterized in that, The humidification unit includes multiple humidification tubes; The multiple humidification pipes are arranged in parallel on the upper surface of the annular soil body; Each of the humidifying tubes has multiple humidifying holes on its tube body.

3. The original loess collapsibility coefficient testing system according to claim 2, characterized in that, The humidification unit also includes a plurality of atomizing nozzles corresponding to the number of humidification holes; One of the atomizing nozzles is disposed on one of the humidification holes.

4. The original loess collapsibility coefficient testing system according to claim 1, characterized in that, The humidification and retention device also includes a water-proof tank; The water-proof groove is disposed inside the shell and is in contact with the lower surface of the annular soil body.

5. The original loess collapsibility coefficient testing system according to claim 1, characterized in that, The constant force jacking device also includes a baffle; One side surface of the baffle is connected to the bottom end of the jacking structure, and the other side surface is in contact with the second sidewall of the annular soil. The second sidewall is disposed opposite to the first sidewall.

6. The original loess collapsibility coefficient testing system according to claim 1, characterized in that, The device for determining the collapsibility coefficient also includes a display unit; The display unit is connected to the processing unit and is used to display the collapsibility coefficient or self-weight collapsibility coefficient of the annular soil.

7. A method for testing the collapsibility coefficient of undisturbed loess using the undisturbed loess collapsibility coefficient testing system according to any one of claims 1-6, characterized in that, include: Obtain the first jacking distance when the constant force jacking device applies a constant jacking force to the annular soil mass; The annular soil is gradually moistened by a humidification and maintenance device, and the second jacking distance is obtained when a constant jacking force is applied to the annular soil with different water contents by a constant force jacking device. The collapse coefficient or self-weight collapse coefficient of the annular soil is determined based on the initial ring width, the first jacking distance, and the second jacking distance.

Images