An in-situ testing device and method for determining the density of coarse-grained soil in a borehole

Abstract

The present application relates to an in-situ testing device and method for measuring the density of coarse-grained soil in a hole, and relates to the field of geological engineering, which includes a bottom plate, a plurality of steel pipes, a plate-pipe assembly, a rubber film bottom plate, a rubber film sleeve, a sealing cover, a cover plate, a sealing casing, a portable vacuum pump, a portable water pressure pump, a pressure gauge, a rubber hose, a water tank, a platform scale, a water level gauge, a film sleeve and a thermometer. Through the reasonable design and combination of these components, combined with specific test steps and calculation methods, the present application realizes the accurate measurement of the density of coarse-grained soil in the hole, improves the test accuracy and efficiency, and has good operation convenience and environmental adaptability.

Description

Technical Field

[0001] The present application relates to the field of geological engineering, and in particular to an in-situ testing device and method for measuring the density of coarse-grained soil in a hole. Background Art

[0002] In the field of geological engineering and geotechnical engineering, accurate determination of the density of coarse-grained soil is of great significance for evaluating foundation bearing capacity, stability and engineering design. Although traditional laboratory test methods can provide relatively accurate data, due to the disturbance of the soil during sampling and changes during transportation, the test results are often quite different from the actual working conditions. Therefore, it is particularly important to develop a method that can directly measure the density of coarse-grained soil in the hole.

[0003] At present, common in-situ testing methods in the hole mainly include standard penetration test, dynamic penetration test and static penetration test. These methods mainly infer the density of the soil indirectly through the changes in physical and mechanical properties. For example, the standard penetration test determines the compactness of the soil by the number of hammer blows, the dynamic penetration test estimates the density of the soil by the change in penetration resistance, and the static penetration test infers the properties of the soil by the change in penetration resistance and lateral friction resistance. Although these methods can reflect the basic characteristics of the soil to a certain extent, they usually require complex equipment and long operation time, and it is difficult to achieve high-precision density measurement.

[0004] In view of the above-mentioned prior art, the inventors believe that the existing in-hole in-situ testing methods still have some shortcomings in practical applications. The first is the low test accuracy. Especially under complex geological conditions, it is difficult to obtain accurate density data due to the unevenness of the soil and the limitations of the testing equipment. Secondly, the testing process is cumbersome and difficult to operate. It requires professional technicians to operate, and the testing cycle is long, which is not conducive to rapid data acquisition. In addition, the existing testing methods are easily affected by the external environment when operating in the hole, such as hole wall collapse and other problems, resulting in reduced reliability of the test results. Therefore, there is an urgent need for an efficient and accurate testing method and device that can directly measure the density of coarse-grained soil in the hole. Summary of the invention

[0005] In order to solve the above technical problems, the present application provides an in-situ testing device and method for measuring the density of coarse-grained soil in a hole.

[0006] In a first aspect, the present application provides an in-situ testing device for measuring the density of coarse-grained soil in a hole, which adopts the following technical solution: An in-situ testing device for measuring the density of coarse-grained soil in a hole comprises a bottom plate, a steel pipe, a rubber membrane bottom film, a rubber membrane sleeve, a sealing cover, a cover plate, a sealing casing, a vacuum pump, a water pressure pump, a pressure gauge, a rubber hose, a first water tank, a second water tank, a first scale, a second scale, a third scale, a water level gauge, a membrane sleeve and a thermometer; the bottom plate is made of 201 or 304 stainless steel, and the upper and lower edges of the bottom plate are arc-angled and polished to be smooth; there are multiple steel pipes, and the multiple steel pipes are coaxially arranged, and two adjacent steel pipes are fixedly connected by bolts; the steel pipe near one end of the bottom plate is welded to the center of the bottom plate, and the steel pipe and the bottom plate form a plate-tube combination; the rubber membrane sleeve is provided with multiple sections, and the multiple sections of the rubber membrane sleeve are coaxially arranged, and the two adjacent sections of the rubber membrane sleeve are fixedly connected, and the rubber membrane sleeve near one end of the rubber membrane bottom film is provided with multiple sections. It is fixedly connected to the rubber membrane bottom sheet, and the total length of the rubber membrane sleeve is greater than the total length of the steel pipe; the sealing cover is made of 304 brushed stainless steel, the sealing cover is cylindrical, and a pressurized water nozzle is provided on the sealing cover; the cover plate is made of 201 stainless steel, and the cross-section of the cover plate is square; the sealing sleeve is made of 304 brushed stainless steel, and the cover plate is fixedly sleeved on the outer side wall of the sealing sleeve; the inner diameter of the sealing sleeve is matched with the outer diameter of the sealing cover; the capacity of the first water tank is 0.5m3, and the capacity of the second water tank is 50L; the upper weighing limit of the first scale is 500kg, and the graduation value is 200g; the upper weighing limit of the second scale is 50kg, and the graduation value is 50g; the upper weighing limit of the third scale is 10kg, and the graduation value is 5g; the film pressing sleeve is used to fix the rubber membrane sleeve.

[0007] By adopting the above technical solution, the density of coarse-grained soil in the hole can be accurately determined. The specific effects are as follows: By using the bottom plate and steel pipe made of 201 or 304 stainless steel, the stability and durability of the structure are ensured, and the measurement error caused by material deformation is reduced. At the same time, the center deviation and vertical deviation of the bottom plate and steel pipe are controlled within a very small range, further improving the accuracy of the measurement.

[0008] The materials of the rubber membrane bottom film and the rubber membrane sleeve have good elasticity and sealing properties, ensuring that no leakage occurs during the water injection process, thereby ensuring the reliability of the measurement results. The use of portable vacuum pumps and water pressure pumps makes the water injection and pumping process simpler and faster, reducing the complexity and time cost of manual operation. By using water tanks, scales, water level gauges and thermometers of various specifications, the water temperature and water level under different conditions can be accurately measured, thereby more comprehensively reflecting the physical properties of the soil in the hole. In summary, this technical solution not only improves the accuracy and reliability of the density determination of coarse-grained soil in the hole, but also simplifies the operation process, improves the comprehensiveness of data collection and the scope of application of the equipment.

[0009] Optionally, the weld seam, upper inner and outer lips and lower inner lip of the sealing sleeve are all subjected to arc angle treatment and polished to be smooth.

[0010] By adopting the above technical solution, the inner and outer lips of the sealing cover and the sealing casing and the inner lip of the lower part of the sealing casing are arc-cornered and polished smooth, ensuring the adaptability and stability of the equipment under various geological conditions.

[0011] Optionally, the rubber membrane sleeve material has good elasticity and sealing properties, and specific requirements may refer to the rubber membrane used for geotechnical triaxial test.

[0012] By adopting the above technical solution, the rubber membrane sleeve has good elasticity and sealing, which can effectively prevent water and soil leakage, ensure the stability of the hole environment during the test, and thus improve the accuracy and reliability of the test results. Specifically, the good elasticity enables the rubber membrane sleeve to adapt to holes of different diameters, while the sealing ensures that water and soil will not leak, further improving the accuracy of the test.

[0013] Optionally, a water tank is also included, which is used to provide sufficient water source, and a valve is provided at the water outlet of the water tank.

[0014] By adopting the above technical solution, the water tank can provide sufficient water for the first water tank, the second water tank and the third water tank; the water outlet of the water tank can be easily controlled by setting the valve.

[0015] In a second aspect, the present application provides an in-situ test method for measuring the density of coarse-grained soil in a hole, which adopts the following technical solution: An in-situ test method for measuring the density of coarse-grained soil in a hole comprises the following steps: S1. Preparation before the test: (b) Before the jth density test, use a Φ146 drill bit to drill into the open hole to the test depth, and weigh the weight of the soil taken during this drilling (m). i＝j ′, measure the drilling tool to obtain the hole depth h j ; Place the plate-tube assembly with the plate end facing downward, and place the plate-tube assembly vertically into the bottom of the hole while connecting the steel pipe; after the plate end is placed at the bottom of the hole, hold the upper steel pipe, keep the steel pipe vertical, and slowly translate the assembly, making a spiral motion from the center of the drill hole to the hole wall to flatten the loose soil at the bottom of the hole; after flattening the loose soil, place the plate-tube assembly in the center of the hole and measure the depth h from the hole mouth to the plate bottom j ′; calculate Δh j =h j -h j ′, if Δh j ≤30cm, the plate-tube assembly can be taken out, and all the loose soil it carries can be scraped off with a scraper immediately, and its total weight m i＝j ", plus the floating soil collected in the previous test, Δmi＝j , calculate the total weight of soil taken from the drilling holes in this test depth interval m j =m i＝j ′+m i＝j ”+Δm i＝j ; If Δh j ≥30cm, the plate-tube assembly should be taken out and the soil should be cleaned again until the requirements are met; (d) Separate the plate-tube assembly from the remaining steel pipes, invert the plate-tube assembly, insert the bottom end of the rubber membrane sleeve from the bottom end of the bottom plate, turn over the plate-tube assembly, and place the bottom plate on a clean pad; connect the pipe opening of the separated steel pipe to the vacuum pump exhaust port with a rubber hose, turn on the vacuum pump to exhaust, while arranging the rubber membrane sleeve near the pipe wall away from the hole wall, connect the remaining steel pipes, and slowly put the bottom end of the assembly into the hole until it reaches the bottom of the hole, and it must not touch the hole wall during the process; (e) Connect the rubber hose to the exhaust nozzle of the vacuum pump, inject air into the cavity space until the rubber membrane sleeve is fully expanded, and then remove the rubber hose from the steel pipe mouth; take soil to pad the periphery of the hole mouth, pass the rubber membrane sleeve through the sealing sleeve cover from below, align the center of the sealing sleeve with the center of the hole and insert it into the hole, and place the outer cover plate steadily on the ground; after it is placed stably, slowly stretch and turn the rubber membrane sleeve outward to make it close to the inner and outer walls of the sealing sleeve, put on the film pressing sleeve to press the rubber membrane sleeve on the cover plate to fix it, and then turn the rubber membrane sleeve outward and put it on the film pressing sleeve again; (f) Place the water level meter into the steel pipe and slowly lower it to the bottom of the pipe; (g) placing the first water tank on the first scale and filling the first water tank with water from the water tank; placing the second water tank on the second scale and filling the second water tank with water from the water tank; (h) Connect one end of the rubber hose to the water outlet of the water tank, place the other end near the orifice, open the water tank valve, exhaust the air in the rubber hose, and close the valve when water flows out from the other end; (i) Slightly flatten a 20 cm section of rubber hose near the water tank outlet, clamp it with a clamp, separate the hose from the water tank outlet, and quickly connect it to the outlet of the second water tank, trying to expel the air between the clamp and the hose opening; slowly lower the other end of the hose opening into the bottom of the hole, and lay the rubber hose flat to ensure smooth water flow; weigh the total weight of the second water tank m0 and the total weight of the first water tank M0 respectively; S2. Test steps: (j) Measure the water temperature T with a thermometer; (k) Raise the rubber hose outlet at one end of the hole bottom by 20-25 cm, raise the water level gauge by 20 cm and fix it, slowly open the valve, and allow the water in the tank to slowly flow into the hole bottom. When the water level gauge shows that the water level has reached the specified level, immediately close the valve, weigh the total weight of the second water tank and the water in the tank m0′, and calculate Δm0=m0-m0′; (l) According to the method of step (i), quickly connect the water inlet from the second water tank to the water inlet of the third water tank, and try to exhaust the air between the clamp and the pipe mouth; (m) During the first test (j=1), the water level gauge should be taken out of the steel pipe, the valve should be opened slowly, and the water in the tank should be slowly injected into the bottom of the hole. When the water level reaches the height of the hole (the water surface is 85mm from the upper lip of the sealing casing), the valve should be closed immediately, and the total weight of the water tank and the water in the tank should be weighed at this time M1, and ΔΔM1=M0-M1 should be calculated; If it is not the first test (j≥2), the water level gauge should be raised to the hole depth h of the previous test. j-1 ′, raise the rubber hose mouth to a height higher than h j-1 ′5cm, slowly open the valve to allow the water in the tank to slowly flow into the bottom of the hole. When the water level meter shows that the water level has reached the specified level, immediately close the valve and weigh the total weight of the water tank and the water in the tank M. j,j , calculate the water weight ΔM in the rubber membrane sleeve of the test section j,j =M0-M j.j ; (n) Repeat step (m) and raise the water level gauge to h j-2 ′、h j-3 ′…, until the test water level reaches the orifice, take out the water level gauge, and weigh the total weight M of the corresponding water tank and the water in the tank j-2,j 、M j-1,j …M 1,j , and calculate ΔM j-1,j =M j,j -M j-1,j , ΔM j-2,j …ΔM 1,j ; (o) Install the pressure gauge on the water pressure pump, firmly connect the water outlet of the water tank to the water inlet of the water pressure pump with a rubber hose, open the valve to exhaust the air in the pump and then close the valve; (p), transferring one end of the rubber hose from the water tank to the first water tank; (q) Remove the upper section of the steel pipe so that the pipe mouth is lower than the hole mouth; Put the sealing cover on the sealing sleeve and press it down hard so that the upper lip of the sealing sleeve can reach the outer flange groove of the sealing cover; Connect the hose on the pump firmly to the sealing cover pressure nozzle; (r) Open the valve of the first water tank, start the hydraulic pump to inject water, and maintain the pressure for at least 5 minutes after reaching the designed pressure. Weigh the total weight of the water tank and the water in the tank at this time M 1,j ', and keep this value unchanged for 5 minutes, turn off the water pressure pump, and calculate ΔM e,j =M 1,j -M 1,j ', the test is over; (s) The design pressure of pressurized water injection should be equal to the initial average lateral water and soil pressure in the hole within the error range; (t) Remove the water pressure pump and pressure gauge, firmly connect the steel pipe mouth to the vacuum pump exhaust port with a rubber hose, connect one end of another rubber hose to the vacuum pump exhaust port, and extend the other end into the water inlet of the water tank, and then start the vacuum pump to pump air and water; (u) When the water in the rubber membrane sleeve is about to be pumped out, turn off the vacuum pump, unplug the rubber hose from the steel pipe mouth, and remove the sealing cover; (v) Flip the rubber film sleeve off the outer wall of the film pressing sleeve, take out the film pressing sleeve, stretch the rubber film sleeve and arrange it around the outer wall of the steel pipe, and tie it tightly with a rubber band; (w) Connect the rubber hose to the steel pipe again, start the vacuum pump, and when the vacuum pump can no longer pump water or air, turn off the vacuum pump and move the rubber belt to the next section of the steel pipe; (x) Slowly lift the assembly, unfold the upper rubber film sleeve, carefully use a scraper and a brush to clean and collect the loose soil attached to the outer wall of the rubber film sleeve, wipe the inner wall with a dry towel and continue to blow the inner wall with an electric hair dryer. After the inner and outer walls are dried, roll the upper rubber film sleeve outward into a ring and smooth it out; (y) Remove the upper steel pipe, move the rubber band to the next steel pipe, and repeat step (x) until the plate-tube assembly is complete; (z) Take out the rubber membrane sleeve and the plate-tube assembly from the hole, wipe off and dry the water film attached to the inner wall of the rubber membrane sleeve, clean and dry the floating soil on the rubber membrane bottom sheet, and stack the rubber membrane sleeve, the plate-tube assembly and the steel pipe neatly; (a1) The floating soil collected from the outer wall is placed on the second and third scales and weighed, recorded as Δm j+1 ; (a2) Carry out corresponding moisture content test and relative density test on site according to the hole depth interval of each in-situ density test. The soil samples shall be prepared in accordance with the requirements of Section 60 of Geotechnical Test Methods (GB / T 50123-2019); The moisture content test should be carried out in accordance with the requirements of Section 5 of Geotechnical Test Methods; The relative density test shall be carried out in accordance with the requirements of Section 61 of Geotechnical Test Methods; The water content of coarse-grained soil in the corresponding hole depth interval is measured i , maximum dry density ρ d max,i , minimum dry density ρ d min,i , and calculate the minimum density ρ min,i ; S3. Experimental data collation and calculation.

[0016] By adopting the above technical solution, the density of coarse-grained soil can be accurately measured in the hole. The specific effects are as follows: by using components such as stainless steel bottom plate, steel pipe, rubber membrane sleeve, etc., the stability and reliability of the test device are ensured, and the soil density in holes of different depths can be accurately measured; by using a vacuum pump and a water pressure pump, the air and moisture in the hole are effectively removed, the influence of external factors on the measurement results is reduced, and the measurement accuracy is improved; the entire test process is divided into multiple steps, and each step has clear operating instructions, so that the test personnel can complete various operations in an orderly manner, reducing the difficulty of operation and improving work efficiency; through multiple measurements and data corrections, especially the use of precision instruments such as water level meters and scales, the accuracy and reliability of the test data are ensured; according to different apertures and geological conditions, the appropriate rubber membrane sleeve is selected, so that the device can be applied to various complex geological environments and has a wide range of applicability.

[0017] Optionally, in step (b), when the steel pipe moves in the hole, the steel pipe is prevented from contacting the hole wall.

[0018] By adopting the above technical solution, it is possible to effectively prevent the steel pipe from contacting the hole wall during movement in the hole, thereby reducing damage to the soil structure of the hole wall and ensuring the accuracy and reliability of the test results. At the same time, avoiding contact with the hole wall can also reduce equipment wear and extend service life.

[0019] Optionally, between step (b) and step (d), the following steps are further included: (c) Depending on the degree of hole collapse, choose rubber membrane sleeves of different diameters. The diameter of the rubber membrane sleeve should be slightly larger than the maximum hole diameter, and the inner and outer surfaces of the rubber membrane sleeve should be dry and free of water.

[0020] By adopting the above technical solution, the test error caused by the collapse of the drilling hole can be effectively prevented. Specifically, a rubber membrane sleeve of appropriate diameter is selected to ensure that the diameter of the rubber membrane sleeve is slightly larger than the maximum hole diameter, so that the rubber membrane sleeve can be smoothly unfolded in the drilled hole. At the same time, the inner and outer surfaces of the rubber membrane sleeve are dry and free of water, which reduces the influence of moisture on the test results and improves the accuracy and reliability of the test. In addition, by weighing and calculating the volume of the rubber membrane bottom sheet, rubber sleeve membrane, stainless steel bottom plate and stainless steel tube in advance, the specific parameters of each component can be accurately grasped, further improving the accuracy and credibility of the test.

[0021] Optionally, before step (b), the method further comprises the following steps: (a) Weigh and calculate the following data: Rubber film volume: V 膜底 =m 膜底 / ρ 膜 , Volume per unit length of rubber sleeve: V 膜壁 =m橡胶膜套 / (ρ 橡胶膜套 *L), Stainless steel bottom plate volume: V 底板 =m 底板 / ρ 钢 , The volume per unit length of stainless steel pipe measured by drainage method: V 钢管 =m w / ρ wT , where ρ wT is the density of pure water at T℃.

[0022] Optionally, S3 includes the following steps: (b1) The volume from the drill bit depth to the bottom plate of the measuring instrument is regarded as the frustum body. The bottom diameter of the frustum body is the outer diameter of the drill bit. The calculation is performed as follows: Where V 0,J is the volume of the imaginary rounded table between the depth of the drill bit and the depth of the bottom plate of the measuring instrument in the jth test (m 3 ); Δh j is the difference between the drill bit depth and the bottom plate depth of the measuring instrument in the jth test (m); D j is the top diameter of the imaginary frustum in the jth test (m); d is the outer diameter of the drill bit (m); Δm 0,j is the mass of the water column at a height of 20 cm in the rubber membrane sleeve during the jth test (kg); ρ wT,j is the density of water (kg / m 3 ); (b2) The volume of the i=jth depth interval is calculated as follows: The volume of the i<j depth interval is calculated as follows: Where V i,j is the volume of the cavity in the i-th depth section during the j-th test (m 3 ); η j is the volume correction coefficient after pressurized water injection in the hole during the jth test. If only density measurement under normal pressure is performed, η=1; ΔM i,j is the weight of water in the rubber membrane sleeve in the i-th depth section of the j-th test (kg); Δm 0,j is the mass of the water column at a height of 20 cm in the rubber membrane sleeve during the jth test (kg); V 膜壁 is the volume per unit length of the rubber membrane wall (m 3 / m); h′ i is the depth interval of the i-th depth (i≤j), the depth of the bottom plate from the orifice (m); ρ wT,j is the density of water (kg / m 3 ); (b3) In the first test (j = 1), h 1,1 The density of the interval segment is calculated as follows: Where ρ1 is the density of the soil in the first depth section during the first test (kg / m 3 ); m1 is the total weight of soil taken from the hole in the first depth section during the first test (kg); ρ min,1 For the first test, the minimum density of the soil sampled from the first depth section (kg) shall be tested and calculated in accordance with Sections 60, 5 and 61 of the Geotechnical Testing Code (GB / T 50123-2019); V 0,1 =The volume of the imaginary rounded table between the depth of the drill bit and the depth of the bottom plate of the measuring instrument during the first test (m 3 ); V 1,1 For the first test, the volume of the first depth section cavity (m 3 ); η1 is the volume correction coefficient after pressurized water injection in the first test. If only density measurement under normal pressure is performed, η=1; for non-first test (j≥2), the density of the i=j interval is calculated as follows: In the formula, ρ i＝j is the density of the soil in the i=jth depth section (kg / m 3 ); m i＝j is the total weight of soil taken from the hole in the i=jth depth section during the jth test (kg); ρ min,i＝j The minimum density of soil sampled from the first depth section during the jth test (kg). The test and calculation shall comply with the provisions of Sections 60, 5 and 61 of the Geotechnical Testing Code (GB / T 50123-2019); V0,j is the volume of the imaginary rounded table between the depth of the drill bit and the depth of the bottom plate of the measuring instrument in the jth test (m 3 ); V i,j is the volume of the cavity in the i-th depth section of the j-th test (m 3 ); η j is the volume correction coefficient after pressurized water injection in the jth test.

[0023] Optionally, S3 further includes the following steps: (b4) During the first test (j=1), the volume correction factor after pressurized water injection is calculated as follows: When it is not the first test (j≥2), the volume correction factor after pressurized water injection is calculated as follows: Where η j is the volume correction factor after pressurized water injection in the jth test; ΔM i,j is the weight of water in the rubber membrane sleeve at the i-th depth section during the j-th test (kg); ΔM e,j is the weight of pressurized water during the jth test (kg); ρ wT,j is the density of water (kg / m 3 ); (b5) The design pressure of pressurized water injection should be equal to the initial average lateral water and soil pressure in the hole within the error range and is determined by the following formula: In the formula, p j is the design pressure of pressurized water injection during the jth test; g is the gravity constant, which is 9.81N / kg; h p is the height difference between the pressure water pump and the orifice (m); h j ' is the depth of the bottom plate from the orifice in the jth test (m); K 0,i is the static earth pressure coefficient of the i-th soil layer, according to calculate; is the effective internal friction angle of the i-th layer of soil (°), which can be obtained by referring to relevant specifications; h i is the bottom depth of the i-th soil layer (m); ρ i′ is the floating density of the i-th layer of soil, and the natural density (kg / m 3 ), when determining the design pressure, it can be considered as normal pressure test, calculated using step (b3), taking η = 1; h w is the depth of groundwater level from the orifice (m); ρ wT,j is the density of water (kg / m 3 ).

[0024] By adopting the above technical scheme, the density of coarse-grained soil in the hole can be accurately measured. Specifically: by considering the area as a frustum and calculating its volume using a formula, the accurate measurement range of the soil sample in the hole during the test is ensured, and the test accuracy is improved; according to the specific conditions of different depth sections, different formulas are used to calculate the cavity volume, and considering the influence of pressurized water injection, a volume correction coefficient is introduced to further improve the accuracy of the test results; in the first test, the volume of the imaginary frustum between the drill bit depth and the bottom plate depth of the measuring instrument and the cavity volume are calculated, combined with the total weight of the soil and the minimum density, to obtain the density value. For non-first tests, the results of the previous tests are also considered to ensure the data continuity and reliability of the entire test process; by introducing the volume correction coefficient after pressurized water injection, the volume change caused by pressurized water injection is compensated, making the final density calculation more accurate; by comprehensively considering the initial average lateral water and soil pressure in the hole, soil layer characteristics and other factors, the design pressure of pressurized water injection is reasonably determined, ensuring the scientific nature of the test conditions, thereby improving the credibility of the test results. In summary, these technical means work together to significantly improve the accuracy and reliability of in-hole coarse-grained soil density measurement.

[0025] In summary, the present application includes at least one of the following beneficial technical effects: 1. By adopting the in-situ test device for measuring the density of coarse-grained soil in the hole, the direct measurement of the in-situ density of coarse-grained soil is realized, which significantly reduces the soil disturbance during the sampling process and improves the accuracy and reliability of the test results; 2. The test device can accurately measure the density of soil in different depth ranges by precisely controlling the pressurized water injection volume and water level changes, avoiding the errors caused by the traditional method that relies on indirect indicators and improving the accuracy and stability of the test; 3. The device is easy to operate, does not require complicated equipment and long-term operation, greatly improves work efficiency, reduces labor costs, and is suitable for field testing under various geological conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a partial structural schematic diagram of the bottom plate and the steel pipe in the embodiment of the present application; Figure 2 It is a partial structural schematic diagram of the rubber film bottom sheet and the rubber film sleeve in the embodiment of the present application; Figure 3 It is a partial structural schematic diagram of the sealing cover in an embodiment of the present application; Figure 4 It is a partial structural schematic diagram of the sealing casing and the cover plate in the embodiment of the present application.

[0027] Explanation of the accompanying reference numerals: 1. bottom plate; 2. steel pipe; 3. plate-tube assembly; 4. rubber membrane bottom plate; 5. rubber membrane sleeve; 6. sealing cover; 7. sealing casing; 8. cover plate. DETAILED DESCRIPTION

[0028] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in the embodiments of the present invention. The described embodiments are only possible technical implementations of the present invention, and are not all possible implementations. Those skilled in the art can fully combine the embodiments of the present invention to obtain other embodiments without creative work, and these embodiments are also within the protection scope of the present invention. The inventor of the present application found that the existing method for measuring the density of coarse-grained soil in a hole has problems such as low accuracy and low efficiency. For this reason, the present application mainly adopts an in-situ testing device for measuring the density of coarse-grained soil in a hole, which achieves the purpose of directly measuring the density of coarse-grained soil in the hole, and effectively improves the test accuracy and efficiency. The present application is further described in detail below.

[0029] Example 1 The in-situ testing device for measuring the density of coarse-grained soil in a hole provided in an embodiment of the present application comprises a base plate 1, a plurality of steel pipes 2, a plate-pipe assembly 3, a rubber membrane base film 4, a rubber membrane sleeve 5, a sealing cover 6, a cover plate 8, a sealing casing 7, a portable vacuum pump, a portable water pressure pump, a pressure gauge, a rubber hose, a water tank, a platform scale, a water level gauge, a film sleeve and a thermometer, wherein a complete testing device is formed through a specific matching relationship between the various components, thereby achieving the purpose of directly measuring the density of coarse-grained soil in the hole and effectively improving the test accuracy and efficiency.

[0030] Specifically, the bottom plate 1 is made of 201 or 304 stainless steel, with a diameter of 100 mm and a thickness of 5 mm, and the upper and lower edges are processed with arc angles and polished to be smooth. The main function of the bottom plate 1 is to serve as the basis of the entire device to ensure its stability and safety in the hole.

[0031] Multiple steel pipes 2 are also made of 201 or 304 stainless steel, DN15, where the 1# pipe has a connecting hole with a diameter of 10mm 15mm away from the bottom, the top is threaded, the bottom of 2~9# pipes are threaded, the top is threaded, and the bottom of 10# pipes is threaded. The function of the steel pipe 2 is to support and extend the entire device to ensure its depth and stability in the hole. The connection method of the steel pipe 2 adopts threaded connection to ensure the reliability of the connection and easy disassembly and maintenance.

[0032] The plate-tube assembly 3 is formed by aligning the bottom end of the 1# pipe with the center of the bottom plate 1 and welding it to the bottom plate 1. The weld height is 5mm and the weld surface is polished and smooth. The plate-tube assembly 3 is one of the core components of the entire device, responsible for connecting the bottom plate 1 and the steel pipe 2 as a whole to ensure its stability and sealing in the hole.

[0033] The rubber film bottom sheet 4 is 2mm thick and has a diameter of 150mm, 200mm, 250mm, 300mm, 350mm. The appropriate size can be selected according to the actual aperture. The main function of the rubber film bottom sheet 4 is to form a closed space at the bottom of the hole for subsequent water injection and pumping operations.

[0034] The rubber membrane sleeve 5 is 0.5mm thick and has a diameter of 150mm, 200mm, 250mm, 300mm, and 350mm. The gaps between the rubber membrane bottom sheet 4 and the rubber membrane sleeve 5 and each section of the rubber membrane sleeve 5 are firmly bonded or hot-melted together, and the total length is greater than 11m. The main function of the rubber membrane sleeve 5 is to form a closed space in the hole to facilitate water injection and pumping operations.

[0035] The sealing cover 6 is made of 304 brushed stainless steel, with a thickness of 1 mm, a height of 85 mm, and an outer diameter of 146 mm. The main function of the sealing cover 6 is to seal the orifice to prevent water and soil leakage and ensure the accuracy of the test.

[0036] The cover plate 8 is made of 201 stainless steel, 5mm thick, square, and 500mm long. The main function of the cover plate 8 is to serve as the top of the entire device to ensure its stability and safety in the hole.

[0037] The sealing sleeve 7 is made of 304 brushed stainless steel, with an outer diameter of 150mm, a thickness of 1.5-1.8mm, an upper height of 80mm, a lower height of 500mm, and is fully welded with the upper and lower fillets of the cover plate 8, with a weld height of 5mm, to form the sealing sleeve 7. The main function of the sealing sleeve 7 is to protect the hole mouth, prevent the hole wall from collapsing, and ensure the smooth progress of the test.

[0038] Portable vacuum pumps are used for air extraction and water pumping operations, portable water pressure pumps are used for water injection operations, pressure gauges are used to monitor water pressure, rubber hoses are used to connect various components, water tanks are used to store water, bench scales are used to weigh the weight of water and soil, water level gauges are used to measure the water level in the hole, film sleeves are used to fix rubber film sleeves 5, and thermometers are used to measure water temperature. The selection of these auxiliary equipment can be adjusted according to actual needs to improve the efficiency and accuracy of the test.

[0039] The implementation principle of this embodiment is: by combining the bottom plate 1, steel pipe 2, rubber membrane bottom plate 4, rubber membrane sleeve 5, sealing cover 6, cover plate 8, sealing casing 7 and other components into a complete testing device, the function of directly measuring the density of coarse-grained soil in the hole is realized. The device calculates the density of the soil body by using the weight and volume change of water through water injection and pumping operations, thereby overcoming the shortcomings of traditional testing methods and improving the accuracy and efficiency of the test. The device has a simple structure, is easy to operate, is suitable for various geological conditions, and has a wide range of application prospects.

[0040] Example 2 The difference between this embodiment and the above embodiment is that the material of the rubber film bottom sheet 4 and the rubber film sleeve 5 is optimized. The material of the rubber film bottom sheet 4 and the rubber film sleeve 5 is silicone rubber with higher elasticity and sealing performance to adapt to more complex geological conditions. In addition, a spare rubber film bottom sheet 4 and rubber film sleeve 5 are added to prepare for emergencies.

[0041] The implementation principle of this embodiment is: by selecting silicone rubber with higher elasticity and sealing as the material of the rubber film bottom film 4 and the rubber film sleeve 5, the reliability and durability of the test device are further improved. The spare rubber film bottom film 4 and the rubber film sleeve 5 can be replaced in time when they are damaged during the test process to ensure the continuity and accuracy of the test. This optimized design makes the test device more suitable for testing under complex geological conditions and improves the flexibility and reliability of the test.

[0042] Example 3 The difference between this embodiment and the above embodiment is that the present embodiment adds processing to the inner and outer lips of the sealing cover 6 and the sealing sleeve 7 and the inner lip of the lower part of the sealing sleeve 7. The inner and outer lips of the sealing cover 6 and the sealing sleeve 7 and the inner lip of the lower part of the sealing sleeve 7 are all processed with arc angles and polished to reduce friction and wear and improve sealing performance.

[0043] Specifically, the inner and outer lips of the sealing cover 6 and the sealing sleeve 7 and the inner lip of the lower part of the sealing sleeve 7 are all processed with arc angles and polished to be smooth, thereby reducing the problem of poor sealing caused by friction and wear during use. This treatment method can significantly improve the sealing performance and ensure the accuracy of the test.

[0044] The implementation principle of this embodiment is: by processing the inner and outer lips of the sealing cover 6 and the sealing sleeve 7 and the inner lip of the lower part of the sealing sleeve 7 with arc angles and polishing them to be smooth, friction and wear are effectively reduced and the sealing performance is improved. This optimized design enables the test device to maintain good sealing performance during long-term use, ensuring the accuracy and reliability of the test.

[0045] Example 4 The difference between this embodiment and the above embodiment is that this embodiment adds control over the center deviation and vertical deviation of the bottom plate 1 and the steel pipe 2. The center deviation of the bottom plate 1 and the steel pipe 2 is ≤1mm, and the vertical deviation is ≤0.5°, so as to ensure the stability and safety of the device in the hole.

[0046] Specifically, the center deviation of the bottom plate 1 and the steel pipe 2 is ≤1mm, and the vertical deviation is ≤0.5°. Through precision machining and assembly processes, the stability and safety of the device in the hole are ensured. This strict control measure can significantly improve the accuracy and reliability of the device.

[0047] The implementation principle of this embodiment is: by strictly controlling the center deviation and vertical deviation of the bottom plate 1 and the steel pipe 2, the stability and safety of the device in the hole are ensured. This optimized design makes the performance of the test device more stable and reliable under various geological conditions, and improves the accuracy and efficiency of the test.

[0048] Example 5 The difference between this embodiment and the above embodiment is that the connection mode between the rubber membrane sleeve 5 and the air suction port of the portable vacuum pump is optimized in this embodiment. The rubber membrane sleeve 5 and the air suction port of the portable vacuum pump are connected by a rubber hose, and the material and structure of the rubber hose are optimized to improve the reliability and sealing of the connection.

[0049] Specifically, the material of the rubber hose is silicone rubber with higher elasticity and sealing to adapt to higher working pressure and temperature. The rubber hose is designed as a double-layer structure, with the inner layer of silicone rubber and the outer layer of nylon braided layer, which enhances its wear resistance and pressure resistance. This optimized design can significantly improve the reliability and sealing of the connection and ensure the accuracy of the test.

[0050] The implementation principle of this embodiment is: by optimizing the connection mode between the rubber membrane sleeve 5 and the air extraction port of the portable vacuum pump, the reliability and sealing of the connection are improved. This optimized design enables the test device to maintain good connection performance during long-term use, ensuring the accuracy and reliability of the test.

[0051] The embodiments of the present application also include the following contents: test preparation and installation and placement of instruments, test steps, data collation and result calculation: S1. Preparation before the test: (a) Weigh and calculate the following data: Rubber film bottom volume: Volume per unit length of rubber sleeve: Stainless steel bottom plate volume: The volume per unit length of stainless steel pipe is measured by drainage method: In the formula, ρ wT is the density of pure water at T℃; (b) Before the jth density test, use a Φ146 drill bit to drill into the open hole to the test depth, and weigh the weight of the soil taken during this drilling (m). i＝j ′, measure the drilling tool to obtain the hole depth h j ; Place the plate-tube assembly with the plate end facing downward, and place the plate-tube assembly vertically into the bottom of the hole while connecting the steel pipe; after the plate end is placed at the bottom of the hole, hold the upper steel pipe, keep the steel pipe vertical, and slowly translate the assembly, making a spiral motion from the center of the drill hole to the hole wall to flatten the loose soil at the bottom of the hole; after flattening the loose soil, place the plate-tube assembly in the center of the hole and measure the depth h from the hole mouth to the plate bottom j ′; calculate Δh j =h j -h j ′, if Δh j ≤30cm, the plate-tube assembly can be taken out, and all the loose soil it carries can be scraped off with a scraper immediately, and its total weight m i＝j ", plus the floating soil collected in the previous test, Δm i＝j , calculate the total weight of soil taken from the drilling holes in this test depth interval m j =m i＝j ′+m i＝j ”+Δm i＝j ; If Δh j ≥30cm, the plate-tube assembly should be taken out, and the soil should be removed and the bottom should be cleaned again until the requirements are met. When the steel pipe moves in the hole, avoid contact between the steel pipe and the hole wall; (c) Depending on the degree of hole collapse, choose rubber membrane sleeves of different diameters. The diameter of the rubber membrane sleeve should be slightly larger than the maximum hole diameter, and the inner and outer surfaces of the rubber membrane sleeve should be dry and free of water; (d) Separate the plate-tube assembly from the remaining steel pipes, invert the plate-tube assembly, insert the bottom end of the rubber membrane sleeve from the bottom end of the bottom plate, turn over the plate-tube assembly, and place the bottom plate on a clean pad; connect the pipe opening of the separated steel pipe to the vacuum pump exhaust port with a rubber hose, turn on the vacuum pump to exhaust, while arranging the rubber membrane sleeve near the pipe wall away from the hole wall, connect the remaining steel pipes, and slowly put the bottom end of the assembly into the hole until it reaches the bottom of the hole, and it must not touch the hole wall during the process; (e) Connect the rubber hose to the exhaust nozzle of the vacuum pump, inject air into the cavity space until the rubber membrane sleeve is fully expanded, and then remove the rubber hose from the steel pipe mouth; take soil to pad the periphery of the hole mouth, pass the rubber membrane sleeve through the sealing sleeve cover from below, align the center of the sealing sleeve with the center of the hole and insert it into the hole, and place the outer cover plate steadily on the ground; after it is placed stably, slowly stretch and turn the rubber membrane sleeve outward to make it close to the inner and outer walls of the sealing sleeve, put on the film pressing sleeve to press the rubber membrane sleeve on the cover plate to fix it, and then turn the rubber membrane sleeve outward and put it on the film pressing sleeve again; (f) Place the water level meter into the steel pipe and slowly lower it to the bottom of the pipe; (g) placing the first water tank on the first scale and filling the first water tank with water from the water tank; placing the second water tank on the second scale and filling the second water tank with water from the water tank; (h) Connect one end of the rubber hose to the water outlet of the water tank, place the other end near the orifice, open the water tank valve, exhaust the air in the rubber hose, and close the valve when water flows out from the other end; (i) Slightly flatten a 20 cm section of rubber hose near the water tank outlet, clamp it with a clamp, separate the hose from the water tank outlet, and quickly connect it to the outlet of the second water tank, trying to expel the air between the clamp and the hose opening; slowly lower the other end of the hose opening into the bottom of the hole, and lay the rubber hose flat to ensure smooth water flow; weigh the total weight of the second water tank m0 and the total weight of the first water tank M0 respectively; S2. Test steps: (j) Measure the water temperature T with a thermometer; (k) Raise the rubber hose outlet at one end of the hole bottom by 20-25 cm, raise the water level gauge by 20 cm and fix it, slowly open the valve, and allow the water in the tank to slowly flow into the hole bottom. When the water level gauge shows that the water level has reached the specified level, immediately close the valve, weigh the total weight of the second water tank and the water in the tank m0′, and calculate Δm0=m0-m0′; (l) According to the method of step (i), quickly connect the water inlet from the second water tank to the water inlet of the third water tank, and try to exhaust the air between the clamp and the pipe mouth; (m) During the first test (j=1), the water level gauge should be taken out of the steel pipe, the valve should be opened slowly, and the water in the tank should be slowly injected into the bottom of the hole. When the water level reaches the height of the hole (the water surface is 85mm from the upper lip of the sealing casing), the valve should be closed immediately, and the total weight of the water tank and the water in the tank should be weighed at this time M1, and ΔΔM1=M0-M1 should be calculated; If it is not the first test (j≥2), the water level gauge should be raised to the hole depth h of the previous test. j-1 'Fix it at the place where the rubber hose is raised to a height higher than h j-1′5cm, slowly open the valve to allow the water in the tank to slowly flow into the bottom of the hole. When the water level meter shows that the water level has reached the specified level, immediately close the valve and weigh the total weight of the water tank and the water in the tank M. j,j , calculate the water weight ΔM in the rubber membrane sleeve of the test section j,j =M0-M j.j ; (n) Repeat step (m) and raise the water level gauge to h j-2 ′、h j-3 ′…, until the test water level reaches the orifice, take out the water level gauge, and weigh the total weight M of the corresponding water tank and the water in the tank j-2,j 、M j-1,j …M 1,j , and calculate ΔM j-1,j =M j,j -M j-1,j , ΔM j-2,j …ΔM 1,j ; (o) Install the pressure gauge on the water pressure pump, firmly connect the water outlet of the water tank to the water inlet of the water pressure pump with a rubber hose, open the valve to exhaust the air in the pump and then close the valve; (p), transferring one end of the rubber hose from the water tank to the first water tank; (q) Remove the upper section of the steel pipe so that the pipe mouth is lower than the hole mouth; Put the sealing cover on the sealing sleeve and press it down hard so that the upper lip of the sealing sleeve can reach the outer flange groove of the sealing cover; Connect the hose on the pump firmly to the sealing cover pressure nozzle; (r) Open the valve of the first water tank, start the hydraulic pump to inject water, and maintain the pressure for at least 5 minutes after reaching the designed pressure. Weigh the total weight of the water tank and the water in the tank at this time M 1,j ', and keep this value unchanged for 5 minutes, turn off the water pressure pump, and calculate ΔM e,j =M 1,j -M 1,j ', the test is over; (s) The design pressure of pressurized water injection should be equal to the initial average lateral water and soil pressure in the hole within the error range; (t) Remove the water pressure pump and pressure gauge, firmly connect the steel pipe mouth to the vacuum pump exhaust port with a rubber hose, connect one end of another rubber hose to the vacuum pump exhaust port, and extend the other end into the water inlet of the water tank, and then start the vacuum pump to pump air and water; (u) When the water in the rubber membrane sleeve is about to be pumped out, turn off the vacuum pump, unplug the rubber hose from the steel pipe mouth, and remove the sealing cover; (v) Flip the rubber film sleeve off the outer wall of the film pressing sleeve, take out the film pressing sleeve, stretch the rubber film sleeve and arrange it around the outer wall of the steel pipe, and tie it tightly with a rubber band; (w) Connect the rubber hose to the steel pipe again, start the vacuum pump, and when the vacuum pump can no longer pump water or air, turn off the vacuum pump and move the rubber belt to the next section of the steel pipe; (x) Slowly lift the assembly, unfold the upper rubber film sleeve, carefully use a scraper and a brush to clean and collect the loose soil attached to the outer wall of the rubber film sleeve, wipe the inner wall with a dry towel and continue to blow the inner wall with an electric hair dryer. After the inner and outer walls are dried, roll the upper rubber film sleeve outward into a ring and smooth it out; (y) Remove the upper steel pipe, move the rubber band to the next steel pipe, and repeat step (x) until the plate-tube assembly is complete; (z) Take out the rubber membrane sleeve and the plate-tube assembly from the hole, wipe off and dry the water film attached to the inner wall of the rubber membrane sleeve, clean and dry the floating soil on the rubber membrane bottom sheet, and stack the rubber membrane sleeve, the plate-tube assembly and the steel pipe neatly; (a1) The floating soil collected from the outer wall is placed on the second and third scales and weighed, recorded as Δm j+1 ; (a2) Carry out corresponding moisture content test and relative density test on site according to the hole depth interval of each in-situ density test. The soil samples shall be prepared in accordance with the requirements of Section 60 of Geotechnical Test Methods (GB / T 50123-2019); The moisture content test should be carried out in accordance with the requirements of Section 5 of Geotechnical Test Methods; The relative density test shall be carried out in accordance with the requirements of Section 61 of Geotechnical Test Methods; The water content of coarse-grained soil in the corresponding hole depth interval is measured i , maximum dry density ρ d max,i , minimum dry density ρ d min,i , and calculate the minimum density ρ min,i ; S3. Experimental data collation and calculation (b1). The volume from the drill bit depth to the bottom plate of the measuring instrument is regarded as a rounded table. The bottom diameter of the rounded table is the outer diameter of the drill bit. The calculation is performed as follows: Where V 0,J is the volume of the imaginary rounded table between the depth of the drill bit and the depth of the bottom plate of the measuring instrument in the jth test (m 3 ); Δh j is the difference between the drill bit depth and the bottom plate depth of the measuring instrument in the jth test (m); D j is the top diameter of the imaginary frustum in the jth test (m); d is the outer diameter of the drill bit (m); Δm 0,j is the mass of the water column at a height of 20 cm in the rubber membrane sleeve during the jth test (kg); ρ wT,j is the density of water (kg / m 3 ); (b2) The volume of the i=jth depth interval is calculated as follows: The volume of the i<j depth interval is calculated as follows: Where V i,j is the volume of the cavity in the i-th depth section during the j-th test (m 3 ); η j is the volume correction coefficient after pressurized water injection in the hole during the jth test. If only density measurement under normal pressure is performed, η=1; ΔM i,j is the weight of water in the rubber membrane sleeve in the i-th depth section of the j-th test (kg); Δm 0,j is the mass of the water column at a height of 20 cm in the rubber membrane sleeve during the jth test (kg); V 膜壁 is the volume per unit length of the rubber membrane wall (m 3 / m); h′ i is the depth interval of the i-th depth (i≤j), the depth of the bottom plate from the orifice (m); ρ wT,j is the density of water (kg / m 3 ); (b3) In the first test (j = 1), h 1,1 The density of the interval segment is calculated as follows: Where ρ1 is the density of the soil in the first depth section during the first test (kg / m 3 ); m1 is the total weight of soil taken from the hole in the first depth section during the first test (kg); ρ min,1 For the first test, the minimum density of the soil sampled from the first depth section (kg) shall be tested and calculated in accordance with Sections 60, 5 and 61 of the Geotechnical Testing Code (GB / T 50123-2019); V 0,1=The volume of the imaginary rounded table between the depth of the drill bit and the depth of the bottom plate of the measuring instrument during the first test (m 3 ); V 1,1 For the first test, the volume of the first depth section cavity (m 3 ); η1 is the volume correction coefficient after pressurized water injection in the first test. If only density measurement under normal pressure is performed, η=1; for non-first test (j≥2), the density of the i=j interval is calculated as follows: In the formula, ρ i＝j is the density of the soil in the i=jth depth section (kg / m 3 ); m i＝j is the total weight of soil taken from the hole in the i=jth depth section during the jth test (kg); ρ min,i＝j The minimum density of soil sampled from the first depth section during the jth test (kg). The test and calculation shall comply with the provisions of Sections 60, 5 and 61 of the Geotechnical Testing Code (GB / T 50123-2019); V 0,j is the volume of the imaginary rounded table between the depth of the drill bit and the depth of the bottom plate of the measuring instrument in the jth test (m 3 ); V i,j is the volume of the cavity in the i-th depth section of the j-th test (m 3 ); η j is the volume correction factor after pressurized water injection in the jth test; (b4) During the first test (j=1), the volume correction factor after pressurized water injection is calculated as follows: When it is not the first test (j≥2), the volume correction factor after pressurized water injection is calculated as follows: Where η j is the volume correction factor after pressurized water injection in the jth test; ΔM i,j is the weight of water in the rubber membrane sleeve at the i-th depth section during the j-th test (kg); ΔM e,j is the weight of pressurized water during the jth test (kg); ρ wT,j is the density of water (kg / m 3 ); (b5) The design pressure of pressurized water injection should be equal to the initial average lateral water and soil pressure in the hole within the error range and is determined by the following formula: In the formula, p j is the design pressure of pressurized water injection during the jth test; g is the gravity constant, which is 9.81N / kg; h p is the height difference between the pressure water pump and the orifice (m); h j ' is the depth of the bottom plate from the orifice in the jth test (m); K 0,i is the static earth pressure coefficient of the i-th soil layer, according to calculate; is the effective internal friction angle of the i-th layer of soil (°), which can be obtained by referring to relevant specifications; h i is the bottom depth of the i-th soil layer (m); ρ i ′ is the floating density of the i-th layer of soil, and the natural density (kg / m 3 ), when determining the design pressure, it can be considered as normal pressure test, calculated using step (b3), taking η = 1; h w is the depth of groundwater level from the orifice (m); ρ wT,j is the density of water (kg / m 3 ).

[0052] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. An in-situ testing device for measuring the density of coarse-grained soil in a hole, characterized by: It comprises a bottom plate (1), a steel pipe (2), a rubber film bottom film (4), a rubber film sleeve (5), a sealing cover (6), a cover plate (8), a sealing sleeve (7), a vacuum pump, a water pressure pump, a pressure gauge, a rubber hose, a first water tank, a second water tank, a first scale, a second scale, a third scale, a water level gauge, a film sleeve and a thermometer; the bottom plate (1) is made of 201 or 304 stainless steel, and the upper and lower edges of the bottom plate (1) are processed with arc angles and polished to be smooth; The steel pipes (2) are provided in plurality, and the plurality of steel pipes (2) are coaxially arranged, and two adjacent steel pipes (2) are fixedly connected by bolts; the steel pipe (2) near one end of the bottom plate (1) is welded to the center of the bottom plate (1), and the steel pipe (2) and the bottom plate (1) form a plate-tube assembly (3); the rubber membrane sleeve (5) is provided in plurality, and the plurality of rubber membrane sleeves (5) are coaxially arranged, and two adjacent rubber membrane sleeves (5) are fixedly connected. The rubber membrane sleeve (5) is fixedly connected to one end of the rubber membrane bottom film (4), and the total length of the rubber membrane sleeve (5) is greater than the total length of the steel pipe (2); the sealing cover (6) is made of 304 brushed stainless steel, the sealing cover (6) is cylindrical, and a pressurized water nozzle is provided on the sealing cover (6); the cover plate (8) is made of 201 stainless steel, and the cross section of the cover plate (8) is square; the sealing sleeve (7) is made of 304 brushed stainless steel, and the cover plate (8) is fixedly sleeved on the outer wall of the sealing sleeve (7); the inner diameter of the sealing sleeve (7) is compatible with the outer diameter of the sealing cover (6); the capacity of the first water tank is 0.5m3, and the capacity of the second water tank is 50L; the upper limit of the weighing of the first platform scale is 500kg, and the graduation value is 200g; the upper limit of the weighing of the second platform scale is 50kg, and the graduation value is 50g; The upper weighing limit of the third scale is 10 kg, and the graduation value is 5 g; the film pressing sleeve is used to fix the rubber film sleeve (5).

2. The in-situ testing device for measuring the density of coarse-grained soil in a hole according to claim 1, characterized in that: The weld seam, upper inner and outer lips and lower inner lip of the sealing sleeve (7) are all subjected to arc processing and polished to be smooth.

3. The in-situ testing device for measuring the density of coarse-grained soil in a hole according to claim 2, characterized in that: The material of the rubber membrane sleeve (5) has good elasticity and sealing properties, and specific requirements can refer to the rubber membrane used in geotechnical triaxial test.

4. The in-situ testing device for measuring the density of coarse-grained soil in a hole according to claim 3, characterized in that: The utility model also comprises a water tank, which is used for providing sufficient water source, and a valve is arranged at the water outlet of the water tank.

5. An in-situ testing method for measuring the density of coarse-grained soil in a hole, based on the in-situ testing device for measuring the density of coarse-grained soil in a hole according to claim 4, characterized in that: The following steps are involved: S1. Preparation before the test: (b) Before the jth density test, use a Φ146 drill bit to drill into the open hole to the test depth, and weigh the weight of the soil taken during this drilling, m. i＝j ′, measure the drilling tool to obtain the hole depth h j ; Place the plate-tube assembly with the plate end facing downward, and place the plate-tube assembly vertically into the bottom of the hole while connecting the steel pipe; after the plate end is placed at the bottom of the hole, hold the upper steel pipe, keep the steel pipe vertical, and slowly translate the assembly, making a spiral motion from the center of the drill hole to the hole wall to flatten the loose soil at the bottom of the hole; after flattening the loose soil, place the plate-tube assembly in the center of the hole and measure the depth h from the hole mouth to the plate bottom j ′; calculate Δh j =h j -h j ′, if Δh j ≤30cm, the plate-tube assembly can be taken out, and all the loose soil it carries can be scraped off with a scraper immediately, and its total weight m i＝j ", plus the floating soil collected in the previous test, Δm i＝j , calculate the total weight of soil taken from the drilling holes in this test depth interval m j =m i＝j ′+m i＝j ”+Δm i＝j ; If Δh j ≥30cm, the plate-tube assembly should be taken out and the soil should be cleaned again until the requirements are met; (d) Separate the plate-tube assembly from the remaining steel pipes, invert the plate-tube assembly, insert the bottom end of the rubber membrane sleeve from the bottom end of the bottom plate, turn over the plate-tube assembly, and place the bottom plate on a clean pad; connect the pipe opening of the separated steel pipe to the vacuum pump exhaust port with a rubber hose, turn on the vacuum pump to exhaust, while arranging the rubber membrane sleeve near the pipe wall away from the hole wall, connect the remaining steel pipes, and slowly put the bottom end of the assembly into the hole until it reaches the bottom of the hole, and it must not touch the hole wall during the process; (e) Connect the rubber hose to the exhaust nozzle of the vacuum pump, inject air into the cavity space until the rubber membrane sleeve is fully expanded, and then remove the rubber hose from the steel pipe mouth; take soil to pad the periphery of the hole mouth, pass the rubber membrane sleeve through the sealing sleeve cover from below, align the center of the sealing sleeve with the center of the hole and insert it into the hole, and place the outer cover plate steadily on the ground; after it is placed stably, slowly stretch and turn the rubber membrane sleeve outward to make it close to the inner and outer walls of the sealing sleeve, put on the film pressing sleeve to press the rubber membrane sleeve on the cover plate to fix it, and then turn the rubber membrane sleeve outward and put it on the film pressing sleeve again; (f) Place the water level meter into the steel pipe and slowly lower it to the bottom of the pipe; (g) placing the first water tank on the first scale and filling the first water tank with water from the water tank; placing the second water tank on the second scale and filling the second water tank with water from the water tank; (h) Connect one end of the rubber hose to the water outlet of the water tank, place the other end near the orifice, open the water tank valve, exhaust the air in the rubber hose, and close the valve when water flows out from the other end; (i) Slightly flatten a 20 cm section of rubber hose near the water tank outlet, clamp it with a clamp, separate the hose from the water tank outlet, and quickly connect it to the outlet of the second water tank, trying to expel the air between the clamp and the hose opening; Slowly lower the other end of the pipe into the bottom of the hole, and place the rubber hose smoothly to ensure smooth water flow; weigh the total weight of the second water tank m0 and the total weight of the first water tank m0 respectively; S2. Test steps: (j) Measure the water temperature T with a thermometer; (k) Raise the rubber hose outlet at one end of the hole bottom by 20-25 cm, raise the water level gauge by 20 cm and fix it, slowly open the valve, and allow the water in the tank to slowly flow into the hole bottom. When the water level gauge shows that the water level has reached the specified level, immediately close the valve, weigh the total weight of the second water tank and the water in the tank m0′, and calculate Δm0=m0-m0′; (l) According to the method of step (i), quickly connect the water inlet from the second water tank to the water inlet of the third water tank, and try to exhaust the air between the clamp and the pipe mouth; (m) During the first test (j=1), the water level gauge should be taken out of the steel pipe, the valve should be opened slowly, and the water in the tank should be slowly injected into the bottom of the hole. When the water level reaches the height of the hole (the water surface is 85mm from the upper lip of the sealing casing), the valve should be closed immediately, and the total weight of the water tank and the water in the tank should be weighed at this time M1, and ΔΔM1=M0-M1 should be calculated; If it is not the first test (j≥2), the water level gauge should be raised to the hole depth h of the previous test. j-1 ′, raise the rubber hose mouth to a height higher than h j-1 ′5cm, slowly open the valve to allow the water in the tank to slowly flow into the bottom of the hole. When the water level meter shows that the water level has reached the specified level, immediately close the valve and weigh the total weight of the water tank and the water in the tank M. j,j , calculate the water weight ΔM in the rubber membrane sleeve of the test section j,j =M0-M j.j ; (n) Repeat step (m) and raise the water level gauge to h j-2 ′、h j-3 ′…, until the test water level reaches the orifice, take out the water level gauge, and weigh the total weight M of the corresponding water tank and the water in the tank j-2,j 、M j-1,j …M 1,j , and calculate ΔM j-1,j =M j,j -M j-1,j , ΔM j-2,j …ΔM 1,j ; (o) Install the pressure gauge on the water pressure pump, firmly connect the water outlet of the water tank to the water inlet of the water pressure pump with a rubber hose, open the valve to exhaust the air in the pump and then close the valve; (p), transferring one end of the rubber hose from the water tank to the first water tank; (q) Remove the upper section of the steel pipe so that the pipe mouth is lower than the hole mouth; Put the sealing cover on the sealing sleeve and press it down hard so that the upper lip of the sealing sleeve can reach the outer flange groove of the sealing cover; Connect the hose on the pump firmly to the sealing cover pressure nozzle; (r) Open the valve of the first water tank, start the hydraulic pump to inject water, and maintain the pressure for at least 5 minutes after reaching the designed pressure. Weigh the total weight of the water tank and the water in the tank at this time M 1,j ', and keep this value unchanged for 5 minutes, turn off the water pressure pump, and calculate ΔM e,j =M 1,j -M 1,j ', the test is over; (s) The design pressure of pressurized water injection should be equal to the initial average lateral water and soil pressure in the hole within the error range; (t) Remove the water pressure pump and pressure gauge, firmly connect the steel pipe mouth to the vacuum pump exhaust port with a rubber hose, connect one end of another rubber hose to the vacuum pump exhaust port, and extend the other end into the water inlet of the water tank, and then start the vacuum pump to pump air and water; (u) When the water in the rubber membrane sleeve is about to be pumped out, turn off the vacuum pump, unplug the rubber hose from the steel pipe mouth, and remove the sealing cover; (v) Flip the rubber film sleeve off the outer wall of the film pressing sleeve, take out the film pressing sleeve, stretch the rubber film sleeve and arrange it around the outer wall of the steel pipe, and tie it tightly with a rubber band; (w) Connect the rubber hose to the steel pipe again, start the vacuum pump, and when the vacuum pump can no longer pump water or air, turn off the vacuum pump and move the rubber belt to the next section of the steel pipe; (x) Slowly lift the assembly, unfold the upper rubber film sleeve, carefully use a scraper and a brush to clean and collect the loose soil attached to the outer wall of the rubber film sleeve, wipe the inner wall with a dry towel and continue to blow the inner wall with an electric hair dryer. After the inner and outer walls are dried, roll the upper rubber film sleeve outward into a ring and smooth it out; (y) Remove the upper steel pipe, move the rubber band to the next steel pipe, and repeat step (x) until the plate-tube assembly is complete; (z) Take out the rubber membrane sleeve and the plate-tube assembly from the hole, wipe off and dry the water film attached to the inner wall of the rubber membrane sleeve, clean and dry the floating soil on the rubber membrane bottom sheet, and stack the rubber membrane sleeve, the plate-tube assembly and the steel pipe neatly; (a1) The floating soil collected from the outer wall is placed on the second and third scales and weighed, recorded as Δm j+1 ; (a2) Carry out corresponding moisture content test and relative density test on site according to the hole depth interval of each in-situ density test. The soil samples shall be prepared in accordance with the requirements of Section 60 of Geotechnical Test Methods (GB / T 50123-2019); The moisture content test should be carried out in accordance with the requirements of Section 5 of Geotechnical Test Methods; The relative density test shall be carried out in accordance with the requirements of Section 61 of Geotechnical Test Methods; The water content of coarse-grained soil in the corresponding hole depth interval is measured i , maximum dry density ρ d max,i , minimum dry density ρ d min,i , and calculate the minimum density ρ min,i ; S3. Experimental data collation and calculation.

6. The in-situ test method for measuring the density of coarse-grained soil in a hole according to claim 5, characterized in that: In step (b), when the steel pipe moves in the hole, the steel pipe is prevented from contacting the hole wall.

7. The in-situ test method for measuring the density of coarse-grained soil in a hole according to claim 6, characterized in that: Between step (b) and step (d), the method further comprises the following steps: (c) Depending on the degree of hole collapse, choose rubber membrane sleeves of different diameters. The diameter of the rubber membrane sleeve should be slightly larger than the maximum hole diameter, and the inner and outer surfaces of the rubber membrane sleeve should be dry and free of water.

8. The in-situ test method for measuring the density of coarse-grained soil in a hole according to claim 7, characterized in that: Before step (b), the method further comprises the following steps: (a) Weigh and calculate the following data: Rubber film bottom volume: Volume per unit length of rubber sleeve: Stainless steel bottom plate volume: The volume per unit length of stainless steel pipe is measured by drainage method: In the formula, ρ wT is the density of pure water at T℃.

9. The in-situ test method for measuring the density of coarse-grained soil in a hole according to claim 8, characterized in that: S3 includes the following steps: (b1) The volume from the drill bit depth to the bottom plate of the measuring instrument is regarded as the frustum body. The bottom diameter of the frustum body is the outer diameter of the drill bit. The calculation is performed as follows: Where V 0,J is the volume of the imaginary rounded table between the depth of the drill bit and the depth of the bottom plate of the measuring instrument in the jth test (m 3 ); Δh j is the difference between the drill bit depth and the bottom plate depth of the measuring instrument in the jth test (m); D j is the top diameter of the imaginary frustum in the jth test (m); d is the outer diameter of the drill bit (m); Δm 0,j is the mass of the water column at a height of 20 cm in the rubber membrane sleeve during the jth test (kg); ρ wT,j is the density of water (kg / m 3 ); (b2) The volume of the i=jth depth interval is calculated as follows: The volume of the i-th < j-th depth interval is calculated as follows: Where V i,j is the volume of the cavity in the i-th depth section during the j-th test (m 3 ); η j is the volume correction coefficient after pressurized water injection in the hole during the jth test. If only density measurement under normal pressure is performed, η=1; ΔM i,j is the weight of water in the rubber membrane sleeve in the i-th depth section of the j-th test (kg); Δm 0,j is the mass of the water column at a height of 20 cm in the rubber membrane sleeve during the jth test (kg); V 膜壁 is the volume per unit length of the rubber membrane wall (m 3 / m); h′ i is the depth interval of the i-th depth (i≤j), the depth of the bottom plate from the orifice (m); ρ wT,j is the density of water (kg / m 3 ); (b3) In the first test (j = 1), h 1,1 The density of the interval segment is calculated as follows: Where ρ1 is the density of the soil in the first depth section during the first test (kg / m 3 ); m1 is the total weight of soil taken from the hole in the first depth section during the first test (kg); ρ min,1 For the first test, the minimum density of the soil sampled from the first depth section (kg) shall be tested and calculated in accordance with Sections 60, 5 and 61 of the Geotechnical Testing Code (GB / T 50123-2019); V 0,1 =The volume of the imaginary rounded table between the depth of the drill bit and the depth of the bottom plate of the measuring instrument during the first test (m 3 ); V 1,1 For the first test, the volume of the first depth section cavity (m 3 ); η1 is the volume correction coefficient after pressurized water injection in the first test. If only density measurement under normal pressure is performed, η=1; for non-first test (j≥2), the density of the i=j interval is calculated as follows: In the formula, ρ i＝j is the density of the soil in the i=jth depth section (kg / m 3 ); m i＝j is the total weight of soil taken from the hole in the i=jth depth section during the jth test (kg); ρ min,i＝j The minimum density of soil sampled from the first depth section during the jth test (kg). The test and calculation shall comply with the provisions of Sections 60, 5 and 61 of the Geotechnical Testing Code (GB / T 50123-2019); V 0,j is the volume of the imaginary rounded table between the depth of the drill bit and the depth of the bottom plate of the measuring instrument in the jth test (m 3 ); V i,j is the volume of the cavity in the i-th depth section of the j-th test (m 3 ); η j is the volume correction coefficient after pressurized water injection in the jth test.

10. The in-situ test method for measuring the density of coarse-grained soil in a hole according to claim 9, characterized in that: S3 also includes the following steps: (b4) During the first test (j=1), the volume correction factor after pressurized water injection is calculated as follows: When it is not the first test (j≥2), the volume correction factor after pressurized water injection is calculated as follows: Where η j is the volume correction factor after pressurized water injection in the jth test; ΔM i,j is the weight of water in the rubber membrane sleeve at the i-th depth section during the j-th test (kg); ΔM e,j is the weight of pressurized water during the jth test (kg); ρ wT,j is the density of water (kg / m 3 ); (b5) The design pressure of pressurized water injection should be equal to the initial average lateral water and soil pressure in the hole within the error range and is determined by the following formula: In the formula, p j is the design pressure of pressurized water injection during the jth test; g is the gravity constant, which is 9.81N / kg; h p is the height difference between the pressure water pump and the orifice (m); h j ' is the depth of the bottom plate from the orifice in the jth test (m); K 0,i is the static earth pressure coefficient of the i-th soil layer, according to calculate; is the effective internal friction angle of the i-th layer of soil (°), which can be obtained by referring to relevant specifications; h i is the bottom depth of the i-th soil layer (m); ρ i ′ is the floating density of the i-th layer of soil, and the natural density (kg / m 3 ), when determining the design pressure, it can be considered as normal pressure test, calculated using step (b3), taking η = 1; h w is the depth of groundwater level from the orifice (m); ρ wT,j is the density of water (kg / m 3 ).

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