A device and method for measuring horizontal deformation coefficient of loess after soaking and humidification

Abstract

The application discloses a kind of loess soaking moistening after horizontal deformation coefficient measuring device and method, including the cavity of cylindrical shell with;Shell includes top cover, side wall and base, and the center position of top cover bottom surface and base top surface is provided with circular step, and ring sample is placed in shell, and the inner diameter of ring sample is same with step diameter, and upper water-permeable stone plate and lower water-permeable stone plate are respectively arranged in the top and bottom end of ring sample, and upper water-permeable stone plate and lower water-permeable stone plate are respectively located between side wall top and bottom and step side wall, and side wall is provided with side wall water-permeable hole at lower water-permeable stone plate position, and top cover is provided with top cover water injection hole at upper water-permeable stone plate position, and top cover center is provided with drill hole;Water bag is arranged in the annular space of ring sample, and water pressure controller is arranged outside shell, and water pressure controller output end is communicated with water bag through drill hole. It can simulate the determination of horizontal deformation coefficient after deep loess soaking moistening.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical engineering testing and relates to a device and method for measuring the horizontal deformation coefficient of loess after it has been soaked and moistened with water. Background Technology

[0002] Collapsible loess is a type of soil with unique properties, characterized by relatively homogeneous texture, loose structure, and well-developed pores. When undisturbed, it generally exhibits high strength and low compressibility. However, when soaked under pressure, its structure rapidly deteriorates, resulting in significant deformation and a rapid decrease in strength. Previous studies have extensively investigated the structure and collapsibility of loess, but most have employed vertical samples. While this approach is reasonable and accurate for foundation engineering projects subjected only to vertical loads, the anisotropy of loess's mechanical properties may be more crucial for complex structures such as slopes, tunnels, and underground structures. Especially when groundwater is present, the collapsibility characteristics at different depths exhibit significant differences in both horizontal and vertical directions, demonstrating heterogeneity. Therefore, studying loess collapsibility from an anisotropic perspective is of great importance.

[0003] According to my country's "Standard for Construction in Collapsible Loess Areas" GB50025-2018, the collapsibility coefficient of loess can be determined through indoor compression tests and field tests. Indoor loess collapsibility testing is simple and convenient, so it is commonly used in engineering projects; however, the results are prone to error. On the other hand, field tests for determining the collapsibility coefficient mainly involve immersion load tests. However, conducting immersion load tests in collapsible loess areas is time-consuming, costly, and involves complex testing conditions. Furthermore, limitations in testing methods result in poor immersion effects on deeper soil layers. Therefore, only the collapsibility deformation of shallow loess strata can be measured, and the variation law of the collapsibility deformation coefficient in deeper loess strata cannot be obtained. According to GB50025-2018, the maximum depth of collapsible loess under its own weight in my country can reach 50m-60m. Since directly measuring the collapsibility of deep loess is very difficult and labor-intensive, it is not suitable for widespread use in engineering projects. Therefore, indirect methods are considered to obtain the collapsibility deformation coefficient of deep loess. However, there is currently a lack of means and methods to indirectly obtain the collapsibility deformation coefficient of deep loess. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a device and method for measuring the horizontal deformation coefficient of loess after immersion in water and humidification, which can simulate the measurement of the horizontal deformation coefficient of deep loess after immersion in water and humidification.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] A device for measuring the horizontal deformation coefficient of loess after immersion in water includes a cylindrical shell with a cavity.

[0007] The shell includes a top cover, side walls, and a base. The bottom of the side walls and the top of the base are connected. The top cover and the top of the side walls are detachably connected. A circular step is provided at the center of the bottom surface of the top cover and the top surface of the base. An annular sample is placed inside the shell. The inner diameter of the annular sample is the same as the diameter of the step. An upper permeable stone slab and a lower permeable stone slab are respectively provided at the top and bottom of the annular sample. The upper permeable stone slab and the lower permeable stone slab are located between the top and bottom of the side walls and the side walls of the steps, respectively. A side wall permeable hole is provided at the position of the lower permeable stone slab. A top cover water injection hole is provided at the position of the upper permeable stone slab. A drilled hole is provided at the center of the top cover.

[0008] A water bladder is placed inside the annular space of the ring-shaped sample, and a water pressure controller is placed outside the shell. The output end of the water pressure controller passes through a drill hole and is connected to the water bladder.

[0009] Preferably, the top cover and the base protrude radially from the top and bottom surfaces of the sidewalls, and the protruding parts of the top cover and the base are connected by fixing screws.

[0010] Preferably, the top cover includes an outer top cover and an inner top cover. The inner top cover is circular with a drilled hole. The outer top cover is annular and nested outside the inner top cover. The outer top cover and the inner top cover are connected by a T-shaped groove and an interface. The water injection hole of the top cover is located on the outer top cover.

[0011] Preferably, when it is necessary to prepare an annular sample, a cylindrical sample preparation rigid body is provided inside the shell, the diameter of the sample preparation rigid body is the same as the diameter of the step, and the top cover of the annular sample is replaced by a sample preparation compactor, and an annular pressure block with the same inner and outer diameter as the annular sample is provided at the bottom of the sample preparation compactor.

[0012] Furthermore, a columnar protrusion is provided at the center of the bottom of the sample body, and a groove positioning hole is provided at the center of the top surface of the base.

[0013] Furthermore, a handle is provided at the center of the top of the sample preparation body.

[0014] Preferably, a valve is provided between the water pressure controller and the water bladder.

[0015] Preferably, the top cover has multiple water injection holes, which are evenly distributed along the annular end face of the annular sample.

[0016] A method for determining the horizontal deformation coefficient of loess after soaking and wetting with water using the aforementioned device includes the following steps:

[0017] S1, Place the annular sample inside the shell to complete the shell assembly;

[0018] S2, the water pressure controller pressurizes the water bladder by gradually increasing the pressure, and records the change in water volume of the water pressure controller when the water bladder expands to a stable volume under each pressure level, so as to obtain the final volume V1 of the water bladder under each pressure level.

[0019] S3, drain the water from the water bladder and inject water into the annular sample through the water injection hole on the top cover until the annular sample is saturated and then stop injecting water;

[0020] S4, repeat S2, and record the final volume V2 of the water bladder at each pressure level;

[0021] S5. Using volumes V1 and V2, plot the pressure-volume change test curves of the soil under un-wetted and wetted conditions, and calculate the horizontal deformation coefficient of the soil under different pressures under wetted conditions using the test curves.

[0022] Preferably, the formula for calculating the horizontal immersion deformation coefficient is:

[0023]

[0024] Where: δ h V1 is the horizontal deformation coefficient after immersion in water and humidification; H is the height of the water bladder; W0 is the radial width of the annular soil sample; V1 is the volume of the water bladder after the sample deformation stabilizes under a certain pressure level; and V2 is the volume of the water bladder after the sample immersion deformation stabilizes under a certain pressure level.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] This invention places an annular sample in a shell, saturates the annular sample through water injection holes in the top cover and water permeable holes in the side wall, and pressurizes the water bladder by injecting water through a water pressure controller. By measuring the volume change of the water bladder and the pressure change of the water pressure controller, the horizontal deformation of deep soil can be measured indoors, and the horizontal deformation coefficient of the soil under different pressures in the humidified state can be obtained.

[0027] Furthermore, the sample preparation body and sidewalls form an annular cavity. The soil sample is then compacted into an annular specimen using a sample compactor. After the annular specimen is prepared, the sample preparation body and sample compactor are removed without affecting subsequent tests.

[0028] Furthermore, the cylindrical protrusions of the sample preparation body and the grooved positioning holes of the base cooperate to ensure that the sample preparation body will not be eccentric, thus avoiding the eccentricity of the inner and outer circles of the prepared annular sample.

[0029] Furthermore, a handle is provided at the center of the top of the sample preparation body for easy removal after use. Attached Figure Description

[0030] Figure 1This is a three-dimensional semi-internal schematic diagram of the test apparatus of the present invention;

[0031] Figure 2 This is a cross-sectional view of the device structure of the present invention;

[0032] Figure 3 This is an enlarged schematic diagram of the top cover structure of the present invention;

[0033] Figure 4 This is a schematic diagram of the rigid body structure for sample preparation according to the present invention;

[0034] Figure 5 This is a schematic diagram of the sample compactor structure of the present invention;

[0035] Figure 6 The pressure-volume change test curves of the soil under un-wetted and wetted conditions are shown in the present invention.

[0036] Wherein: 1-base; 2-groove positioning hole; 3-side wall permeable hole; 4-side wall; 5-lower permeable stone slab; 6-ring soil sample; 7-upper permeable stone slab; 8-water bladder; 9-inner top cover; 10-outer top cover; 11-drill hole; 12-top cover water injection hole; 13-fixing screw; 14-water pressure controller; 15-sample preparation rigid body; 16-valve; 17-sample preparation compactor. Detailed Implementation

[0037] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0038] It should be noted that the terms “front,” “back,” “left,” “right,” “up,” and “down” used in the following description refer to the directions shown in the attached diagram, while the terms “inside” and “outside” refer to the directions toward or away from the geometric center of a specific component, respectively.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0040] like Figure 1 and Figure 2As shown, the present invention discloses a device and method for measuring the horizontal deformation coefficient of loess after soaking and moistening. The device includes a base 1, a groove positioning hole 2, a side wall permeable hole 3, a side wall 4, a lower permeable stone slab 5, an upper permeable stone slab 7, a water bladder 8, an inner top cover 9, an outer top cover 10, a drill hole 11, a top cover water injection hole 12, a fixing screw 13, a water pressure controller 14, a sample preparation rigid body 15, a valve 16, and a sample preparation compactor 17.

[0041] The bottom of the side wall 4 and the top of the base 1 are integrally connected. The inner top cover 9 and the outer top cover 10 form the top cover. The top cover and the top of the side wall 4 are detachably connected. A circular step is set at the center of the bottom surface of the top cover and the top surface of the base 1. An annular sample 6 is placed inside the shell. The inner diameter of the annular sample 6 is the same as the diameter of the step. The top and bottom of the annular sample 6 are respectively provided with an upper permeable stone slab 7 and a lower permeable stone slab 5. The upper permeable stone slab 7 and the lower permeable stone slab 5 are respectively located between the top and bottom of the side wall 4 and the side wall of the step. The side wall 4 is provided with a side wall permeable hole 3 at the position of the lower permeable stone slab 5.

[0042] like Figure 3 As shown, the top cover is provided with a water injection hole 12 at the position of the upper permeable stone slab 7. There are multiple water injection holes 12, which are evenly distributed along the annular end face of the annular sample 6. A drill hole 11 is provided in the center of the top cover.

[0043] The inner top cover 9 is circular, and the drill hole 11 is provided on the inner top cover 9. The outer top cover 10 is annular and nested outside the inner top cover 9. The outer top cover 10 and the inner top cover 9 are connected by a T-shaped groove and interface. The top cover water injection hole 12 is provided on the outer top cover 10.

[0044] A water bladder 8 is placed inside the annular space of the annular sample 6. A water pressure controller 14 is placed outside the shell. The output end of the water pressure controller 14 passes through the drill hole 11 and is connected to the water bladder 8. A valve 16 is placed between the water pressure controller 14 and the water bladder 8. The water pressure controller 14 is connected to a host computer. The model of the water pressure controller is LFTD1404.

[0045] The inner top cover 9 is circular, and the drill hole 11 is provided on the inner top cover 9. The outer top cover 10 is annular and nested outside the inner top cover 9. The outer top cover 10 and the inner top cover 9 are connected by a T-shaped groove and interface. The top cover water injection hole 12 is provided on the outer top cover 10.

[0046] When it is necessary to prepare cyclic sample 6, such as Figure 4 As shown, a cylindrical sample preparation body 15 is provided inside the shell. The diameter of the sample preparation body 15 is the same as the diameter of the step. The top cover of the annular sample 6 is replaced by a sample compactor 17, as shown. Figure 5 As shown, the bottom of the sample compactor 17 is provided with an annular pressing block with the same inner and outer diameters as the annular sample 6.

[0047] The sample preparation body 15 has a columnar protrusion at the center of its bottom, and a groove positioning hole 2 is provided at the center of the top surface of the base 1. The sample preparation body 15 has a handle at the center of its top.

[0048] The following steps are included in the determination of the horizontal deformation coefficient of loess under water immersion in an indoor environment using this device:

[0049] Step 1: Place the base 1 and side wall 4 in the horizontal area, place the permeable stone slab 5 on the base 1, with the upper edge of the permeable stone slab 5 flush with the upper edge of the protruding part of the base 1, and then place the annular filter paper on the permeable stone slab 5.

[0050] Step two: Align the protruding lower part of the sample preparation body 15 with the positioning hole 2 of the base groove and place it on the base 1. At this time, a horizontally confined area is formed between the outer periphery of the sample preparation body 15 and the inner edge of the side wall 4. Add an appropriate amount of loess to the confined area and compact it with the sample compactor 17 to form a ring-shaped soil sample 6. Measure and record the width W0 of the ring-shaped soil sample.

[0051] Step 3: Place the annular filter paper and the upper permeable stone slab 7 on the annular sample 6 in sequence. Then place the outer top cover 10 on the upper permeable stone slab 7, and then use the fixing screw 13 to connect and fix the outer top cover 10 to the base 1.

[0052] Step 4: Slowly rotate and remove the sample preparation body 15 to ensure the integrity of the annular soil sample 6. Remove the fixing screw 13, take out the outer top cover 10, and put the water bag 8 into the empty space after the sample preparation body 15 is removed. The upper circular tube part of the water bag 8 extends out through the inner top cover drill hole 11 and connects to the water pressure controller 14.

[0053] Step 5: Install the inner top cover 9 and the outer top cover 10 in sequence, and then use the fixing screws 13 to fix the top cover.

[0054] Step 6: Open valve 16 and inject an appropriate amount of water into water bladder 8 so that the lower part of water bladder 8 fits tightly against the inner wall of the annular soil sample. Record the volume V0 of water bladder 8 at this time.

[0055] Step 7: Turn on the water pressure controller 14 and increase the pressure in stages, with each stage increasing the pressure by 25 kPa. Before and after each stage of load increase, measure and record the water volume change of the water pressure controller 14. At this time, the water bladder 8 will undergo radial deformation under this pressure. After the deformation stabilizes, record the volume V1 of the water bladder 8. Finally, pressurize the water bladder 8 to a certain value and then turn off the water pressure controller 14.

[0056] Step 8: Drain the water from the water bag 8, and then inject water through the top cover water injection hole 12, through the upper permeable stone slab 7, into the annular soil sample 6 to saturate the soil sample. The water injection rate should be greater than the permeability coefficient of the soil sample. When the injected water can be seen to flow steadily out of the side wall permeable hole 3 through the lower permeable stone slab 5, it indicates that the soil sample has been completely saturated. At this point, stop injecting water.

[0057] Step nine, the same as step seven, is to turn on the water pressure controller 14 and pressurize using a step-by-step pressurization method. Before and after each step of load increase, the water volume change of the water pressure controller 14 is measured and recorded once. Under this pressure, the water bladder 8 will undergo radial deformation. After the deformation stabilizes, the volume V2 of the water bladder 8 at this time is recorded. Finally, the water bladder 8 is pressurized to the same value as in step seven, and then the valve 16 and the water pressure controller 14 are closed.

[0058] Step 10 allows plotting pressure-volume change test curves for both the un-wetted and wetted soil states, as well as the wetted soil state. Figure 6 As shown, curve α is the pressure-volume change test curve of soil under un-watered and moistened conditions, and curve β is the pressure-volume change test curve of soil under watered and moistened conditions. Based on these curves, the horizontal deformation coefficient of soil under different pressures under watered and moistened conditions can be calculated, providing an indirect method for obtaining the loess collapsibility deformation coefficient. The formula for calculating the horizontal water-immersion deformation coefficient is as follows:

[0059]

[0060] In the formula: δh is the horizontal deformation coefficient after immersion and moistening; H is the height of the water bladder 8 in cm; W0 is the radial width of the annular soil sample 6 in cm; and V1 is the volume of the water bladder 8 after the sample deformation stabilizes under a certain pressure level in cm³. 3 V2 is the volume of the water bladder 8 after the sample has stabilized after immersion in water under a certain pressure level, in cm³. 3 .

[0061] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0062] It should be understood that the above description is for illustrative purposes and not for limitation. Many embodiments and applications beyond the provided examples will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of this teaching should not be determined by reference to the above description, but rather by reference to the foregoing claims and the full scope of their equivalents. For purposes of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended as a waiver of that subject matter, nor should it be construed as an indication that the applicant has not considered that subject matter as part of the disclosed inventive subject matter.

Claims

1. A device for measuring the horizontal deformation coefficient of loess after immersion in water, characterized in that, Includes a cylindrical shell with cavities; The shell includes a top cover, side walls (4) and a base (1). The bottom of the side wall (4) is connected to the top of the base (1). The top cover is detachably connected to the top of the side wall (4). A circular step is provided at the center of the bottom surface of the top cover and the top surface of the base (1). An annular sample (6) is placed inside the shell. The inner diameter of the annular sample (6) is the same as the diameter of the step. The top and bottom ends of the annular sample (6) are respectively provided with an upper permeable stone slab (7) and a lower permeable stone slab (5). The upper permeable stone slab (7) and the lower permeable stone slab (5) are respectively located between the top and bottom of the side wall (4) and the side wall of the step. The side wall (4) is provided with a side wall permeable hole (3) at the position of the lower permeable stone slab (5). The top cover is provided with a top cover water injection hole (12) at the position of the upper permeable stone slab (7). A drill hole (11) is provided in the center of the top cover. A water bladder (8) is provided in the annular space of the annular sample (6), and a water pressure controller (14) is provided outside the shell. The output end of the water pressure controller (14) passes through the drill hole (11) and is connected to the water bladder (8). When it is necessary to prepare an annular sample (6), a cylindrical sample preparation rigid body (15) is provided inside the shell. The diameter of the sample preparation rigid body (15) is the same as the diameter of the step. The top cover of the annular sample (6) is replaced by a sample preparation compactor (17). The bottom of the sample preparation compactor (17) is provided with an annular pressure block with the same inner and outer diameter as the annular sample (6). The bottom center of the sample preparation rigid body (15) is provided with a columnar protrusion, and the top center of the base (1) is provided with a groove positioning hole (2). A handle is provided at the center of the top of the sample preparation rigid body (15).

2. The device for measuring the horizontal deformation coefficient of loess after immersion and moistening according to claim 1, characterized in that, The top cover and base (1) protrude radially from the top and bottom surfaces of the sidewall (4), and the protruding parts of the top cover and base (1) are connected by fixing screws (13).

3. The device for measuring the horizontal deformation coefficient of loess after immersion and wetting according to claim 1, characterized in that, The top cover includes an outer top cover (10) and an inner top cover (9). The inner top cover (9) is circular, and a drill hole (11) is provided on the inner top cover (9). The outer top cover (10) is annular and nested outside the inner top cover (9). The outer top cover (10) and the inner top cover (9) are connected by a T-shaped groove and an interface. The top cover water injection hole (12) is provided on the outer top cover (10).

4. The device for measuring the horizontal deformation coefficient of loess after immersion and wetting according to claim 1, characterized in that, A valve (16) is provided between the water pressure controller (14) and the water bladder (8).

5. The device for measuring the horizontal deformation coefficient of loess after immersion and wetting according to claim 1, characterized in that, The top cover has multiple water injection holes (12), which are evenly distributed along the annular end face of the annular sample (6).

6. A method for determining the horizontal deformation coefficient of loess after immersion and wetting based on the device described in any one of claims 1-5, characterized in that, Includes the following processes: S1, place the annular sample (6) inside the shell and complete the assembly of the shell; S2, the water pressure controller (14) pressurizes the water bladder (8) by gradually increasing the pressure, and records the water volume change of the water pressure controller (14) when the water bladder (8) expands to a stable volume under each pressure level, so as to obtain the final volume V1 of the water bladder (8) under each pressure level; S3, drain the water from the water bag (8), inject water into the annular sample (6) through the water injection hole (12) on the top cover, and stop injecting water after the annular sample (6) is saturated; S4, repeat S2, and record the final volume V2 of the water bladder (8) at each pressure level; S5. Using volumes V1 and V2, plot the pressure-volume change test curves of the soil under un-wetted and wetted conditions, and calculate the horizontal deformation coefficient of the soil under different pressures under wetted conditions using the test curves.

7. The method for determining the horizontal deformation coefficient of loess after immersion and wetting according to claim 6, characterized in that, The formula for calculating the deformation coefficient under horizontal immersion is: In the formula: It is the horizontal deformation coefficient after immersion in water and humidification; It is the height of the water bladder (8). It is the radial width of the annular soil sample (6). It is the volume of the water bladder (8) after the sample deformation stabilizes under a certain pressure level. It is the volume of the water bladder (8) after the sample has been immersed in water and its deformation has stabilized under a certain pressure.

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