A combined measurement device and method for maximum dry density and bearing ratio of rock and soil

Abstract

The present invention discloses a device and method for measuring the maximum dry density and bearing ratio of rock and soil. The measuring device includes a compaction system and a penetration system. A positioning sleeve is placed on the top of the sample in the compaction cylinder, a limit plate is provided above the positioning sleeve, and multiple tangential longitudinal positioning channels are provided inside the positioning sleeve. A rotating disk is provided above the positioning sleeve, and multiple hammers are installed on the bottom of the rotating disk through a hammer rod, and the hammers match the positioning channels. The top of the rotating disk is connected to the force-bearing end of the lever. The penetration device includes a penetration rod, the outer wall of the penetration rod is provided with a thread, a horizontal bevel gear is threadedly connected to the penetration rod, the horizontal bevel gear is meshed with the vertical bevel gear, the vertical bevel gear is connected to the rocking plate, and the outer shell is fixedly connected to the base of the compaction system. The present invention integrates two different test devices with obvious conflicts in spatial distribution into one device, saves the time of switching instruments on the basis of ensuring the accuracy of the test, simplifies the test steps, and improves the test efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of geotechnical engineering, and relates to a device and method for measuring the maximum dry density and bearing ratio of geotechnical materials. Background Art

[0002] The maximum dry density and bearing ratio of rock and soil are key parameters in construction quality control. Using a standard compactor and a material strength tester is a reliable method for compacting soil and obtaining its bearing ratio. The current measurement method uses a standard compactor and a pavement material strength tester. To obtain both parameters simultaneously, separate experiments are required, resulting in repeated testing of similar test steps, which is inefficient. The two different sets of test equipment required for different tests also take up a lot of storage space. When using a standard compactor to tamp soil, there are problems such as large amounts of test rock and soil, slow speed, uneven distribution of hammer marks, difficulty in demolding, and moisture content errors and damage to the specimens caused by improper drainage during specimen coring and compaction. Traditional penetration devices require cumbersome operating procedures, making it difficult to control the penetration speed during the penetration test, which can easily lead to non-standard data. Furthermore, compaction and bearing ratio tests require power, and compaction tests cannot be performed during power outages. Summary of the Invention

[0003] In order to solve the above problems, the present invention provides a joint measurement device for the maximum dry density and bearing ratio of rock and soil, which integrates two different test devices with obvious conflicts in spatial distribution into one device, and can obtain the maximum dry density and bearing ratio of rock and soil. On the basis of ensuring the accuracy of the test, it saves the time of switching instruments during the test, simplifies the test steps, and improves the test efficiency. It has the advantages of low cost, small size and high stability.

[0004] Another object of the present invention is to provide a method for jointly determining the maximum dry density and bearing ratio of rock and soil.

[0005] The technical solution adopted by the present invention is to provide a device for measuring the maximum dry density and bearing ratio of rock and soil, including a compaction system and a penetration system;

[0006] The compaction system includes a compaction cylinder, a positioning sleeve is placed on the top of the sample in the compaction cylinder, a limit plate is provided above the positioning sleeve, a plurality of tangential longitudinal positioning channels are provided inside the positioning sleeve, a rotating disk is provided above the positioning sleeve, a plurality of hammers are installed at the bottom of the rotating disk through a striking rod, the striking rod passes through the limit plate, and the hammers match the positioning channels; the top of the rotating disk is connected to the force-bearing end of the lever through a steel wire rope;

[0007] The penetration system includes a penetration device, which includes a penetration rod. A shell is installed on the outside of the penetration rod, and two longitudinal slots are provided on opposite sides of the inner wall of the shell. A crossbeam extending radially is provided on the top of the penetration rod, and the end of the crossbeam is slidably connected to the slot. A thread is provided on the outer wall of the penetration rod, and a horizontal bevel gear is threadedly connected to the penetration rod. The horizontal bevel gear is meshed with the vertical bevel gear, and the vertical bevel gear is connected to the rocker. The shell is fixedly connected to the base of the compaction system.

[0008] Furthermore, there are seven positioning channels, one located in the center, and the remaining six are evenly distributed around the central positioning channel; each hammer is connected to the rotating disk through a corresponding striking rod, and there are four hammers, one in the center and three evenly distributed around; the limiting plate matches the cross-sectional shape of the positioning sleeve, and the limiting plate is fixedly connected to the positioning sleeve through a detachable connecting column at the bottom, and a center hole is provided in the center of the limiting plate, and the center striking rod passes through the center hole; a rotating hole is provided on the limiting plate at a position corresponding to the circumference of the rotational motion of the outer striking rod, and the outer striking rod passes through the rotating hole, and each time the rotating disk rotates, the positioning channel corresponding to the outer striking rod changes accordingly.

[0009] Furthermore, there are two sets of hammers, one set is a light hammer and the other set is a heavy hammer.

[0010] Furthermore, the compaction cylinder includes multiple layers, each layer is a hollow cylinder, and is spliced by two half-moon steel plates with S-shaped interfaces; a pad is placed in the bottom layer of the compaction cylinder, and a surplus soil cylinder is placed on the upper surface of the top compaction cylinder.

[0011] Furthermore, the top and bottom surfaces of the lowest layer of the compaction cylinder are provided with protrusions, a groove for placing a pad is provided at the center of the base, and an annular inclined surface with a higher inner side and a lower outer side is provided to match the protrusion; and a drainage ditch is provided on the outer periphery of the annular inclined surface, and the seepage water tray is placed at the drainage ditch of the base, and the drainage ditch is used to guide the water seeping out during the compaction process to flow into the seepage water tray.

[0012] Furthermore, a probe is installed at the lower end of the penetration rod, and the probe is connected to the pressure gauge signal to detect the penetration load and display it through the pressure gauge. The pressure gauge is installed on the upper part of the shell.

[0013] Furthermore, the compaction cylinder is installed on an iron frame, which includes a stabilizing frame, which is connected and fixed to each layer of compaction cylinder by screws; vertical rods are provided on both sides of the shell, and the lower ends of the vertical rods are connected to the stabilizing frame through connecting sleeves; two horizontal fixing rods stably clamp the shell through an arc-shaped clamping part, and the end of the fixing rod away from the shell is a threaded rod, which passes through the vertical rod, and an adjusting nut is installed on the threaded rod extending out of the vertical rod to adjust the position of the two fixing rods.

[0014] A combined determination method for maximum dry density and bearing ratio of rock and soil comprises the following steps:

[0015] S1: Take a number of rock and soil samples and air-dry them to constant weight, then test the moisture content of the air-dried rock and soil samples; then spray the air-dried rock and soil samples with different water contents, including rock and soil samples with moisture contents above and below the plastic limit;

[0016] S2: Apply a corresponding weight to the force-applying end of the lever and raise the hammer to the height limited by the limit plate; place the rock and soil sample processed in S2 into the compaction cylinder, and then lower the positioning sleeve to the upper surface of the uncompacted rock and soil sample; remove the weight, and the hammers fall simultaneously along the positioning channel to complete one compaction;

[0017] S3: A weight of corresponding weight is applied to the force-applying end of the lever to raise the hammer to the initial height position limited by the limit plate. The rotating disk is rotated to adjust the position of the hammer so that it is directly above another positioning channel, and the above hammer lowering process is repeated;

[0018] S4: Compact the rock and soil sample until it is level with the top surface of the compaction cylinder of the second layer, thus completing the compaction of the first layer of rock and soil sample; repeat the above compaction process to complete the compaction of multiple layers of rock and soil sample;

[0019] S5: After the rock and soil sample is compacted under a certain compaction work, the compaction cylinder and the formed specimen are taken out from the device, demoulded, and the height h, diameter D and mass m of the specimen are measured. The mass m of the water in the seepage tray is weighed. 渗出水 , use probe type moisture sensor to measure the moisture content of the specimen; calculate the dry density;

[0020] S6: Repeat the above compaction and calculation steps to obtain the moisture content and dry density of multiple groups of rock and soil samples; take the moisture content w as the horizontal axis and the dry density ρ as the horizontal axis. d As the vertical coordinate, draw the dry density-water content relationship curve. The horizontal and vertical coordinates of the highest point in the curve are the optimal water content and maximum dry density of the rock and soil sample.

[0021] S7: Prepare the test sample according to the optimal moisture content, complete the compaction of the rock and soil sample under a certain compaction work, remove the compaction cylinder and the formed test piece, flatten the top of the test piece, and weigh the mass of the test piece m2;

[0022] S8: Remove the damaged filter paper on the top of the specimen and replace it with a complete filter paper. Install an adjustable porous plate on top and add several load weights to the porous plate to make the surface of the specimen as flat as possible during the water expansion process. Measure the volume of the specimen before immersion in water.

[0023] S9: Place the specimen in a container, add water until the water level covers the top of the specimen, soak it in water, pour out the water on the top, and let it stand to drain; measure the volume of the specimen after expansion and calculate the expansion amount; weigh the weight m3 of the specimen after soaking in water and calculate the changes in the humidity and density of the specimen;

[0024] S10: Fix the penetration device above the specimen and align the probe to make full contact with the top surface of the specimen; rotate the rocker to adjust the pressure gauge pointers to integers and record the initial reading; rotate the rocker to press the penetration rod into the specimen at a speed of 1 to 1.25 mm / min while measuring the pressure gauge reading; record the amount of rocker rotation when the pressure gauge reaches an integer reading, and calculate the penetration amount by the number of rocker rotations: l = l r ×R; where l is the penetration; l r is the extension and contraction of the penetration rod when the rocking plate rotates one circle, and R is the number of rotations of the rocking plate;

[0025] S11: Use unit pressure p as the abscissa, i.e., the penetration load; and penetration l as the ordinate to draw a pl relationship curve. If the initial segment of the curve is concave, it needs to be corrected. To do this, draw a tangent line at the point of variable curvature, and intersect the ordinate at point o', which is the corrected origin.

[0026] S12: Calculate the material bearing ratio CBR based on the unit pressure and the standard pressure.

[0027] Furthermore, the dry density is calculated according to the following formula:

[0028]

[0029] Among them, ρ d is the dry density of the sample; m is the mass of the sample; m 渗出水 is the mass of water discharged during the compaction process; w is the moisture content of the sample; h is the height of the sample; and D is the diameter of the sample.

[0030] Furthermore, the compaction process in S5 or S7 includes 1-2 partial hammer drops, that is, the central hammer does not drop, and only the outer three hammers drop to complete the compaction; or only the central hammer drops to complete the compaction, and the outer three hammers do not drop.

[0031] The beneficial effects of the present invention are:

[0032] 1. The present invention improves the structure of the penetration device and combines it with the compaction lever structure to form a combined measuring device. This allows the maximum dry density and bearing ratio of rock and soil samples, which originally required two different sets of devices, to be completed on the same instrument. This simplifies the test steps while ensuring the accuracy of the test, saves the time and labor costs of switching instruments during the test, and saves the space for storing instruments after the test, thereby improving the test efficiency.

[0033] 2. The present invention uses a lever method to compact only by gravity without interference from other forces, and falls quickly; combined with the specific position and combination of the positioning channel, the rotating disk and the hammer, the path of the hammer is accurately guided, so that the compaction work can be applied more accurately and evenly to the compaction surface of the sample, thereby improving the compaction uniformity and controlling only part of the hammer to fall, accurately reaching the number of compactions required by the regulations, thereby more accurately conducting tests according to the compaction work required by the regulations, greatly improving the accuracy of the test data and the compaction efficiency.

[0034] 3. This invention uses a dry density calculation formula to more accurately calculate the dry density by weighing the water mass in the seepage water tray. This overcomes the drawbacks of existing methods that take the compaction and drainage process into account, and is closer to actual conditions. A probe-type moisture content sensor is used to test molded specimens at different heights and depths, and the average value is taken as the moisture content of the specimen. Specimens with optimal moisture content and maximum dry density can also be subjected to other tests, such as rebound modulus, to avoid damage to the specimen and high costs associated with coring.

[0035] 4. The test device of the present invention is compact, portable, and easy to operate. It can be tested without power supply, which reduces the requirements of the test on the operating environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 Schematic diagram of the overall device of the embodiment of the present invention.

[0038] Figure 2 It is a plan view of the compaction system according to an embodiment of the present invention.

[0039] Figure 3 Schematic diagram of the entire lever according to an embodiment of the present invention.

[0040] Figure 4 This is an overall schematic diagram of each layer of compaction cylinder in an embodiment of the present invention.

[0041] Figure 5 Schematic diagram of the cross section of each layer of compaction cylinder in an embodiment of the present invention.

[0042] Figure 6 Schematic diagram of the overall positioning sleeve according to an embodiment of the present invention.

[0043] Figure 7Schematic diagram of the cross section of a positioning sleeve according to an embodiment of the present invention.

[0044] Figure 8 Schematic diagram of the entire limit plate according to an embodiment of the present invention.

[0045] Figure 9 Schematic diagram of the hammer according to an embodiment of the present invention.

[0046] Figure 10 Schematic diagram of the fixed pulley according to an embodiment of the present invention.

[0047] Figure 11 Schematic diagram of the overall penetration system.

[0048] Figure 12 Schematic cross-section of the penetration device.

[0049] In the figure, 11-base, 12-stabilizing frame, 2-compacting cylinder, 201-threaded hole, 202-handle, 203-threaded fastener, 204-S-shaped interface, 205-groove, 206-protrusion, 21-first layer compacting cylinder, 211-pad, 22-second layer compacting cylinder, 23-third layer compacting cylinder, 24-fourth layer compacting cylinder, 3-residual soil cylinder, 4-positioning sleeve, 41-positioning channel, 5-rotating disk, 5 1-rotating shaft, 6-hammer, 61-strike rod, 7-limiting plate, 71-rotating hole, 72-connecting column, 73-center hole, 81-lever, 82-connecting rod, 83-fixed pulley, 84-weight, 91-connecting sleeve, 92-adjusting nut, 93-fixing rod, 94-vertical rod, 101-housing, 102-penetration rod, 103-probe, 104-pressure gauge, 105-rocker, 106-horizontal bevel gear. DETAILED DESCRIPTION

[0050] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0051] Example 1,

[0052] A combined measuring device for maximum dry density and bearing ratio of rock and soil, such as Figure 1 As shown, it includes compaction system and penetration system;

[0053] The compaction system includes a base 11, a 30cm long x 30cm wide x 15cm thick steel plate fixed horizontally to the ground. A stabilizing frame 12, consisting of two slender steel cylinders, is screwed to either side of the base 11. The stabilizing frame 12 is screwed to the compaction cylinder 2 of each layer. This ensures the stability of the sample inside the cylinder during the compaction process and provides a connection point for the penetration device assembly.

[0054] like Figure 2 、 4 As shown in Figure 5, the compaction cylinder 2 has four layers, namely the 1st, 2nd, 3rd and 4th layers, namely the first compaction cylinder 21, the second compaction cylinder 22, the third compaction cylinder 23 and the fourth compaction cylinder 24. Each layer is a hollow cylinder with a radial thickness of 3 cm (the difference between the inner and outer diameters) and an inner diameter of 15.2 cm. The height of the first compaction cylinder 21 is 5 cm, and the interior is used to place a pad 211. The pad 211 is a steel block with a diameter of φ15.2×a height of 5 cm, which is used to withstand the force of the hammer 6; the height of the other three compaction cylinders 2 are 4 cm, which are respectively used to hold rock and soil samples. The compaction cylinders 2 of the 2nd, 3rd and 4th layers are all spliced by two half-moon steel plates with S-shaped interfaces 24. They are more tightly connected through the S-shaped interfaces 24 to avoid dislocation and separation of the half-moon steel plates during the compaction process of the hammer 6.

[0055] The upper surface of the topmost compaction cylinder 2 is aligned with the excess soil cylinder 3, which is connected and fixed by the protrusion below the excess soil cylinder 3 and the groove above the fourth compaction cylinder 24; when each layer is compacted, it is used to hold excess rock and soil samples to prevent them from overflowing the compaction cylinder. The layered design of the compaction cylinder 2 facilitates the installation of the bottom pad 211 before compaction, the filling of soil materials and the determination of the compaction height. At the same time, the compaction cylinder 2 can be opened by the handles 202 on both sides, making it easier to demold the compacted sample. The compaction cylinders 2 of each layer are connected to the base 11 by a combination of various methods such as annular grooves, threads and stabilizing frames 12, which improves the overall stability of the device.

[0056] like Figure 6 As shown, the positioning sleeve 4 is a hollow cylinder, which is directly placed on the top surface of the soil sample. The inner diameter of the positioning sleeve 4 is 15.2×height 31 cm, and the radial thickness is 3 cm. Seven longitudinal positioning channels 41 are provided inside the positioning sleeve 4, one positioning channel 41 is located in the center of the positioning sleeve 4, and the remaining six positioning channels 41 are evenly distributed around the central positioning sleeve 4; each positioning channel 41 has a diameter of 5 cm, and the positioning sleeve 4 except the positioning channel 41 is an integrated metal cylinder. The positioning channel 41 is used to limit the falling trajectory of the control hammer 6 to ensure that the hammer mark is distributed according to the specified position, avoiding the problem of uneven distribution of compaction work due to local force, and thus the soil sample cannot be fully compacted.

[0057] A limit plate 7 is provided above the positioning sleeve 4. The limit plate 7 matches the cross-sectional shape of the positioning sleeve 4, with an inner diameter of 15.2 × a height of 0.3 cm. The limit plate 7 is fixedly connected to the positioning sleeve 4 through two connecting columns 72 at the bottom. The connecting columns 72 are detachable and are used to limit the falling height of the hammer 6 to 30 cm or 45 cm respectively; a center hole 73 is provided in the center of the limit plate 7, and the central driving rod 61 passes through the center hole 73; a circular arc-shaped rotation hole 71 is provided on the limit plate 7 at a position corresponding to the circumference of the rotational movement of the outer driving rod 61, as shown Figure 8 , slightly wider than the diameter of the outer hammer 61 for the passage of the outer hammer 61. The outer hammer 6 falls, passes through the first group of three outer positioning channels 41, and then the rotating disk 5 drives the hammer 61 to rotate 60° along the rotating hole 71, passes through the second group of three outer positioning channels 41, and after falling, it rotates again in the opposite direction to switch back to the original positioning channel 41. This cycle repeats, and the hammer 61 moves along the rotating hole 71, driving the hammer 6 to rotate to the corresponding positioning channel 41 to adjust the falling position of the hammer 6.

[0058] The positioning channel 41 is 31 cm high, the same height as the positioning sleeve 4. The bottom of the limit plate 7 has a slightly raised magnetic connector, about 0.2 cm, which can be magnetically connected to the end of the 15 cm long connecting column 72.

[0059] Achieving Different Drop Heights: Limiting plate 7 limits the height of hammer 6. For light compaction tests, the connecting column 72 is removed, and the stopper plate 7 joint rests on the positioning sleeve 4. Hammer 6 drops directly from the top of the positioning sleeve 4. The drop height is 30 cm (the height of the positioning sleeve 4, 31 cm) plus the thickness of the joint, 0.2 cm, minus the height of hammer 6, 1.2 cm. Similarly, for heavy compaction tests, the stopper plate 7 joint is connected to the 15 cm connecting column 72, increasing the drop height to 45 cm.

[0060] There are two sets of hammers 6: one set is light hammers, each light hammer is a steel hammer with a base diameter of 5 cm x height of 1.2 cm and a mass of 2.5 kg; the other set is heavy hammers, each heavy hammer is a steel hammer with a base diameter of 5 cm x height of 1.2 cm and a mass of 4.5 kg. Each set has four hammers, one of which is located directly above the central positioning channel 41, and the other three hammers 6 are evenly distributed directly above the three surrounding positioning channels 41, as shown in the figure. Figure 7 As shown. Figure 9As shown, the four hammers 6 are connected to the rotating disk 5 via a driving rod 61. A rotating shaft 51 is mounted at the top center of the rotating disk 5. The rotating disk 5 is a steel plate with a diameter of φ15.2 and a height of 0.5 cm. By rotating the rotating shaft 51 on the upper portion of the rotating disk 5, the driving rod 61 at the center passes through the center hole 73, and the three surrounding driving rods 61 rotate around the rotation holes 71 on the outer sides of the stop plate 7. With each rotation, the three hammers 6 are distributed directly above the other three positioning channels 41. The number of hammers 6 provided in this embodiment of the present invention is related to the number of positioning channels, the arc length of the rotation holes 71, and other factors. In this embodiment, the number of hammers 6 achieves compaction over a wide area of the specimen surface with uniform distribution of compaction work. The rotating disk 5 is connected to the hammers 6 via the driving rods 61. Rotation of the rotating disk 5 drives the outer hammers 6 to rotate along the rotation holes 71, adjusting their descent path. This ensures that the compaction work is more accurately and evenly applied to the specimen's compaction surface, improving the accuracy of the test data and compaction efficiency.

[0061] The soil compaction process is categorized into light and heavy compaction based on soil particle size. Different compaction processes require different compaction work per layer and per drop of hammer 6. The present invention utilizes an adjustable drop height limiter 7, two switchable hammer sets of varying weights, and adjustable compaction times to meet the varying compaction requirements of light and heavy compaction tests, respectively, broadening the range of applicable sample particle sizes.

[0062] The top and bottom surfaces of the first layer of compaction cylinder 21 are both provided with protrusions 206; a groove with an inner diameter of 15.2 cm and a depth of 5 cm is provided at the center of the base 11 (for placing the pad 211), and an inclined annular slope (high inside and low outside) with an inner diameter of 18.2 cm and an outer diameter of 19.2 cm is also provided (for placing the first layer of compaction cylinder 21), and a small groove is provided at a certain outer circumference of the annular slope, and a seepage water tray is placed at the outlet of the small groove of the base 11 for storing water discharged during the compaction process. The small groove is used to guide the water seeping out during the compaction process into the seepage water tray.

[0063] The two half-moon steel plates that constitute the second layer compaction cylinder 22, the third layer compaction cylinder 23, and the fourth layer compaction cylinder 24 are provided with a groove 205 with a width of 3 cm and a depth of 0.5 cm on the top surface, a protrusion 206 with a width of 3 cm and a height of 0.5 cm on the bottom surface, and a handle 202 is provided at the center of the side of the half-moon steel plate; the bottom surface of the residual soil cylinder 3 is provided with a protrusion 206 with a width of 3 cm and a height of 0.5 cm; a threaded hole 201 is provided on the outside of each layer of compaction cylinder 2 near the bottom of the handle 202, and when each layer is compacted, it is fixedly connected to the stabilizing frame 12 by a threaded fastener 203.

[0064] like Figure 3 、 10As shown, through the lever principle, the lever 81 simultaneously completes the raising of the four hammers 6 through the smaller weight 84; the force-bearing end of the lever 81 is connected to the rotating shaft 51 on the rotating disk 5 through the two fixed pulleys 83 via a steel wire rope; the two fixed pulleys 83 are fixed to the force-bearing end of the lever 81 through corresponding connecting rods 82, and the steel wire rope is tangent to the fixed pulley 83, so that the force transmitted to the rotating disk 5 by the steel wire rope is vertically downward. Before the test begins, a weight 84 of a corresponding weight is applied to the force-applying end of lever 81, limiting the four hammers 6 to a certain height via limit plate 7. During the compaction test, weight 84 is removed, and hammer 6 is lowered to a certain height to complete a compaction of the sample in compaction tube 2. After a compaction, a weight 84 of the required weight is applied to the force-applying end of lever 81, raising hammer 6 to the height limited by limit plate 7. The shaft 51 is then manually rotated to position the other three hammers 6 above other positioning holes in positioning sleeve 4. The weight 84 is then removed, and the above operation is repeated to complete multiple compaction cycles. By using the lever to raise and lower hammer 6, the test can be completed without power supply, reducing the requirements for the operating environment.

[0065] The penetration system includes a hand-cranked penetration device and an iron frame. The hand-cranked penetration device includes a penetration rod 102. A housing 101 is mounted on the outside of the penetration rod 102. Two longitudinal slots are provided on opposite sides of the inner wall of the housing 101. A radially extending crossbeam is mounted on the top of the penetration rod 102. The ends of the crossbeam are slidably connected to the slots to restrict the movement of the penetration rod 102 to a vertical direction. A probe 103 is mounted on the front end of the penetration rod 102. The probe 103 is connected to a pressure gauge 104 for signal detection and display on the pressure gauge 104. The pressure gauge 104 is mounted on the top of the housing 101.

[0066] The outer wall of the penetration rod 102 is provided with a thread, and the horizontal bevel gear 106 is threadedly connected to the penetration rod 102. The horizontal bevel gear 106 is engaged with the vertical bevel gear, and the vertical bevel gear is connected to the rocker 105. Rotating the rocker 105 drives the horizontal bevel gear 106 to rotate, driving the penetration rod 102 to penetrate downward.

[0067] like Figure 11-12 As shown, the iron frame includes two vertical rods 94, which are distributed on both sides of the shell 101. The lower ends of the vertical rods 94 are connected to the stabilizing frame 12 through the connecting sleeve 91; two horizontal fixing rods 93 stably clamp the shell 101 through the arc-shaped clamping part, and the end of the fixing rod 93 away from the shell 101 is a threaded rod, which passes through the vertical rod 94. The threaded rod extending out of the vertical rod 94 is equipped with an adjusting nut 92. The position of the two fixing rods 93 is adjusted to complete the fixation of the shell 101.

[0068] The hand-cranked penetration device of this embodiment is connected to the stabilizing frame 12 through an iron frame to form a penetration system, and there is no need to move the sample to different devices many times. The hand-cranked penetration device greatly reduces the volume of the penetration device while retaining the penetration function, so that the penetration device of the present invention can be combined with the compaction device to form a system to achieve the joint determination of dry density and load ratio. Since the thread pitch and gear radius in the penetration device are fixed, the depth of insertion of the penetration rod is fixed for each rotation of the rocking plate. The penetration depth per unit time can be more accurately controlled by the number of rotations of the rocking plate. By replacing the motor drive with a mechanical drive, the test can be carried out even in the absence of power supply, which increases the feasibility of the device.

[0069] Example 2,

[0070] A combined determination method for maximum dry density and bearing ratio (CBR) of rock and soil comprises the following steps:

[0071] S1: Place the four corners of the base 11 of the device on the hard ground by rotating the screws, and place the seepage water tray at the outlet of the small ditch in the groove; inlay and connect the groove in the center of the base 11, the first layer compaction cylinder 21, the second layer compaction cylinder 22 and the bottom and top protrusions 206 or grooves 205 of the residual soil cylinder 3 in sequence, fix the first layer compaction cylinder 21 and the second layer compaction cylinder 22 to the stabilizing frame 12 by threaded fasteners 203, and place the pad 211 into the first layer compaction cylinder 21.

[0072] S2: Take several rock and soil samples and air-dry them to constant weight. Test the moisture content of the air-dried samples. Then, divide the air-dried samples into five piles and spray them with varying amounts of water, increasing the moisture content by 2% to 3% each time. Two piles each contain rock and soil samples with moisture contents above and below the plastic limit. Each pile is then divided into three equal parts for compaction in three separate rounds.

[0073] S3: Apply corresponding weights 84 to the force-applying end of the lever 81 to lift the four hammers 6 to the height position limited by the limit plate 7;

[0074] S4: Place one portion of any rock and soil sample processed in S2 into the second layer compaction cylinder 22 and the residual soil cylinder 3, and then place the positioning sleeve 4 onto the upper surface of the uncompacted rock and soil sample;

[0075] S5: The weight 84 is removed, and the four hammers 6 fall simultaneously along the positioning channel 41 to complete a compaction;

[0076] S6: A weight 84 of corresponding weight is applied to the force-applying end of the lever 81 to raise the four hammers 6 to the initial height position limited by the limit plate 7. The rotating shaft 51 on the top surface of the rotating disk 5 is rotated to adjust the other three hammers 6 to be directly above the other three positioning holes around the positioning sleeve 4. The above-mentioned lowering process of the hammers 6 is repeated;

[0077] S7: compacting the first rock and soil sample to the same level as the top surface of the second layer of compaction cylinder 22, thus completing the compaction of the first (layer) rock and soil sample;

[0078] S8: Remove the positioning sleeve 4 and the residual soil cylinder 3 in turn, then insert the bottom surface protrusion 206 of the third layer compaction cylinder 23 into the top surface groove 205 of the second layer compaction cylinder 22, load the second pile of rock and soil samples into the third layer compaction cylinder 23, install the residual soil cylinder 3 and the positioning sleeve 4 on the third layer compaction cylinder 23 in turn, repeat the above compaction process, and complete the compaction of the second portion (layer) of rock and soil samples; finally, install the fourth layer compaction cylinder 24 and other operations to continue to complete the compaction of the third portion (layer) of rock and soil samples.

[0079] S9: In the light experiment: in the compaction of each layer of rock and soil samples, the four hammers 6 fell simultaneously 14 times. At the 15th time, the hammer 6 in the center did not complete the fall, and only the three outer hammers 6 fell to complete the compaction (the hammers 6 and hammer rods 61 that did not need to be compacted were removed). That is, the compaction of each layer was equivalent to a single hammer 6 falling for 59 times.

[0080] In the heavy-duty test, the four hammers 6 dropped simultaneously 24 times during each compaction layer. During the 25th and 26th drops, the three outer hammers 6 did not complete their drops, and only the center hammer 6 dropped to complete the compaction (the hammers 6 and the hammer rod 61 not required for compaction were removed). This means that each compaction layer was equivalent to a single hammer 6 dropping 98 times.

[0081] S10: After completing three layers of compaction of the rock and soil sample at a certain compaction work (59 or 98 times of 6-drop compaction with the hammer), remove the compaction cylinder and the molded specimen from the device, pull out the outer handles of the second, third, and fourth layers of compaction cylinders to demould, and then measure and weigh the diameter, height, and mass of the molded specimen. Weigh the mass of water discharged during the compaction process, that is, the mass of water in the seepage water tray.

[0082] S11: Push outward the handles on both sides of each layer of compaction cylinder to demould the compacted sample, measure the sample height h, diameter D and mass m, and weigh the mass m of water in the seepage tray. 渗出水 A probe-type moisture content sensor was used to test the different heights and depths of the molded specimens, and the average value was taken as the moisture content of the specimen.

[0083] S12: Calculate the dry density using the following formula:

[0084]

[0085] S13: where ρ d is the dry density of the sample (g / cm 3 ); m is the mass of the sample (g); m 渗出水 is the mass of water discharged during the compaction process; w is the moisture content of the sample (%); h is the height of the sample (cm); and D is the diameter of the sample (cm).

[0086] S14: After the dry density test of the first pile of rock and soil samples is completed, repeat the above compaction and calculation steps to obtain the moisture content and dry density of the other 4 piles of rock and soil samples.

[0087] S15: With moisture content w as the horizontal axis, dry density ρ d A dry density-moisture content relationship curve is drawn as the vertical axis, and the horizontal and vertical coordinates of the highest point in the curve are the optimal moisture content and maximum dry density of the rock and soil sample.

[0088] S16: Measure the optimum moisture content of the soil sample according to the methods of the first two steps and prepare three samples according to the optimum moisture content, which will be compacted three times for the bearing ratio test.

[0089] S17: Install the device according to the requirements of compaction test S1

[0090] S18: Complete the soil compaction process according to the steps of compaction test S3 to S9.

[0091] S19: In the load ratio test, during each layer of compaction, the four hammers 6 dropped simultaneously 24 times. During the 25th and 26th drops, the three outer hammers 6 did not complete their drops, and only the central hammer 6 dropped to complete the compaction. This means that during each layer of compaction, a single hammer 6 dropped 98 times.

[0092] S20: After completing the three-layer compaction of the rock and soil sample under a certain compaction work (98 times of hammer 6 dropping and compacting), the remaining soil tube 3 and the formed test piece are taken out from the device, and the compacted test piece is smoothed with a straight scraper, and the uneven surface is repaired with fine material; the pad 211 is taken out, and the mass m2 of the test piece is weighed.

[0093] S21: After the specimen is made, remove the damaged filter paper on the top and replace it with a complete piece of filter paper. An adjustable porous plate is installed on top, and several load weights 84 are added to the porous plate to ensure that the surface of the specimen is as flat as possible during the expansion process, making it easier to measure the expansion.

[0094] S22: Place the compacting cylinder 2 on the base 11, connect the iron frame to the stabilizing frame 12 through the connecting sleeve 91, rotate the adjusting nut 92 to adjust the position of the fixing rod 93, fix the dial indicator for measuring the expansion above the specimen, and read the initial reading.

[0095] S23: Remove the compaction cylinder 2 and the test piece, place them in a sufficiently large container, fill with water so that the water level is 2.5 cm above the top of the test piece, and soak them in water for 4 days and nights.

[0096] S24: After soaking in water, take out the test piece in the compaction cylinder 2 from the container, pour out the water on the top surface, and let it stand for 15 minutes to drain.

[0097] S25: Place the compaction cylinder 2 and the test piece on the base 11, rotate the adjusting nut 92 to adjust the position of the fixing rod 93, fix the dial indicator for measuring expansion above the test piece, and read the dial indicator reading.

[0098]

[0099] Where V is the expansion, expressed as a percentage (%); Δh is the change in specimen height after immersion in water (cm); and h is the original specimen height (cm).

[0100] S26: Remove the additional load weight 84, the porous plate, the filter paper, and the spacer 211. Weigh the weight m3 of the specimen after soaking in water, and calculate the changes in humidity and density of the specimen;

[0101] Water absorption of the specimen after soaking in water: ω a =m3-m2; where ω a Indicates water absorption, unit (g);

[0102] Wet density of specimen: Among them, 2177 is the volume of the test tube (cm 3 ).

[0103] S27: Remove the expansion test dial indicator and secure the penetration device above the specimen using the iron stand. Rotate the adjustment nut 92 to adjust the position of the fixing rod 93, aligning the probe 103 to ensure full contact with the top surface of the specimen.

[0104] S28: Rotate the rocker 105 to adjust the pointers of the pressure gauge 104 to integers and record the initial readings.

[0105] S29: Rotate the rocker to press the penetration rod 102 into the specimen at a speed of 1 to 1.25 mm / min, and simultaneously record the reading of the pressure gauge 104. Record the rotation amount of the rocker when the pressure gauge 104 is an integer reading, such as (20, 40, 60). Calculate the penetration amount by the number of rotations of the rocker, so that the penetration amount is 250×10 -2 mm, there can be more than 5 readings. The first reading of the pressure gauge 104 should be the penetration of 30×10 -2 mm. Penetration calculation:

[0106] l=l r ×R

[0107] Where, l is the penetration (mm); l r is the extension and contraction amount of the penetration rod when the rocker rotates one circle (mm), and R is the number of rotations of the rocker (turns).

[0108] S30: Draw a pl curve using unit pressure (p) as the abscissa, i.e., the penetration load, as measured by the force dial gauge, and the penetration (l) as the ordinate. If the initial segment of the curve is concave, a correction is required. To do this, draw a tangent line at the point of variable curvature. The intersection of the tangent line with the ordinate at point o' is the corrected origin.

[0109] S31: The ratio of the unit pressure to the standard pressure when the penetration is 2.5 mm is used as the bearing capacity ratio (CBR) of the material. The calculation formula is:

[0110]

[0111] At the same time, calculate the load ratio when the penetration is 5mm:

[0112]

[0113] Where: p is the unit pressure (kPa), CBR is the bearing ratio of soil (%), accurate to 0.1.

[0114] S32: If the load ratio at 5 mm penetration is greater than that at 2.5 mm penetration, the test shall be repeated. If the result is still the same, the load ratio at 5 mm penetration shall be used.

[0115] Test Example 1,

[0116] The method of Example 2 was adopted, the drop distance was 45 cm, and the volume of the compaction cylinder 2 was 2177 cm 3 , the number of blows per layer is 98; the mass of hammer 6 is 4.5 kg, and the content of particles with a diameter greater than 5 mm is 5%; the compaction test data are shown in Table 1.

[0117] Table 1 Compaction test data of Test Example 1

[0118]

[0119] Test Example 2,

[0120] The method of Example 2 was adopted, the drop distance was 45 cm, and the volume of the compaction cylinder 2 was 997 cm 3 , the number of blows per layer is 27; the mass of hammer 6 is 4.5 kg, and the content of particles with a diameter greater than 5 mm is 5%; the compaction test data are shown in Table 2.

[0121] Table 2 Compaction test data of Test Example 2

[0122]

[0123]

[0124] Table 3 Comparison of test data of the embodiment of the present invention and the existing road material strength tester

[0125]

[0126] It can be seen from the test data in Tables 1-3 that the maximum dry density obtained by the combined measuring device of the embodiment of the present invention is consistent with the test data obtained by the standard compaction test; the penetration depth (penetration amount) obtained by the combined measuring device of the embodiment of the present invention is consistent with the test data obtained by the standard test of the bearing ratio when it is 2.5 mm and 5 mm respectively.

[0127] Determining the maximum dry density and bearing ratio of soil previously required two separate tests using different equipment. Determining the bearing ratio required a separate penetration test. Existing penetration test instruments, such as highway material strength testers, are bulky, and the penetration test load device and compaction instrument are co-located above the specimen, creating a significant spatial conflict.

[0128] The embodiment of the present invention forms a combined measuring device through a penetration device of a specific structure in combination with a compaction lever structure, so that the measurement test of the maximum dry density and bearing ratio of rock and soil samples, which originally required two sets of different devices, can be completed on the same instrument. On the basis of ensuring the accuracy of the test results, the layout of each system is compact and the space is fully utilized, which greatly reduces the size of the device, simplifies the test steps, saves the time and labor costs of switching instruments during the test, and saves the space for storing instruments after the test, improves the test efficiency, and can complete the compaction and penetration process without power supply, and has stronger environmental adaptability.

[0129] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

Claims

1. A device for measuring the maximum dry density and bearing ratio of rock and soil, characterized in that: Including compaction system and penetration system; The compaction system includes a compaction cylinder (2), a positioning sleeve (4) is placed on the top of the sample in the compaction cylinder (2), a limiting plate (7) is provided above the positioning sleeve (4), a plurality of tangential longitudinal positioning channels (41) are provided inside the positioning sleeve (4), a rotating disk (5) is provided above the positioning sleeve (4), a plurality of hammers (6) are installed at the bottom of the rotating disk (5) through a striking rod (61), the striking rod (61) passes through the limiting plate (7), and the hammers (6) match the positioning channels (41); the top of the rotating disk (5) is connected to the force-bearing end of the lever (81) through a steel wire rope; The penetration system includes a penetration device, which includes a penetration rod (102). A housing (101) is installed on the outside of the penetration rod (102). Two longitudinal slots are provided on opposite sides of the inner wall of the housing (101). A crossbeam extending in the radial direction is provided on the top of the penetration rod (102). The end of the crossbeam is slidably connected to the slot. A thread is provided on the outer wall of the penetration rod (102). A horizontal bevel gear (106) is threadedly connected to the penetration rod (102). The horizontal bevel gear (106) is meshed with a vertical bevel gear. The vertical bevel gear is connected to a rocking plate (105). The housing (101) is fixedly connected to a base (11) of the compaction system. There are seven positioning channels (41), one of which is located in the center, and the other six are evenly distributed around the positioning channel (41) in the center; each hammer (6) is connected to the rotating disk (5) through a corresponding hammer rod (61), and the number of hammers (6) is four, one in the center and three evenly distributed around; the cross-sectional shape of the limiting plate (7) matches that of the positioning sleeve (4), and the limiting plate (7) is fixedly connected to the positioning sleeve (4) through a detachable connecting column (72) at the bottom, and a center hole (73) is provided at the center of the limiting plate (7), and the center hammer rod (61) passes through the center hole (73); a rotating hole (71) is provided on the limiting plate (7) at a position corresponding to the circumference of the rotational movement of the outer hammer rod (61), and the outer hammer rod (61) passes through the rotating hole (71), and each time the rotating disk (5) rotates, the positioning channel (41) corresponding to the outer hammer rod (61) changes accordingly; The compaction cylinder (2) comprises multiple layers, each layer being a hollow cylinder formed by splicing two half-moon steel plates with S-shaped interfaces (24); a cushion block (211) is placed in the bottom layer of the compaction cylinder (2), and a surplus soil cylinder (3) is placed on the upper surface of the top compaction cylinder (2) in alignment; The top and bottom surfaces of the lowest layer of the compaction cylinder (2) are both provided with protrusions (206); a groove for placing a pad (211) is provided at the exact center of the base (11); and an annular inclined surface with a higher inner side and a lower outer side is also provided, which matches the protrusion (206); and a drainage ditch is provided on the outer periphery of the annular inclined surface, and a seepage water tray is placed at the drainage ditch of the base (11), and the drainage ditch is used to guide water seeping out during the compaction process to flow into the seepage water tray.

2. The device for measuring the maximum dry density and bearing ratio of rock and soil according to claim 1, characterized in that: The hammer (6) has two sets, one set is a light hammer and the other set is a heavy hammer.

3. The device for measuring the maximum dry density and bearing ratio of rock and soil according to claim 1, characterized in that: A probe (103) is installed at the lower end of the penetration rod (102). The probe (103) is connected to a pressure gauge (104) for signal detection and display through the pressure gauge (104). The pressure gauge (104) is installed on the upper part of the housing (101).

4. The device for measuring the maximum dry density and bearing ratio of rock and soil according to claim 1, characterized in that: The compacting cylinder (2) is mounted on an iron frame platform, which includes a stabilizing frame (12) connected and fixed to each layer of the compacting cylinder (2) via screws; vertical rods (94) are provided on both sides of the shell (101), and the lower ends of the vertical rods (94) are connected to the stabilizing frame (12) via connecting sleeves (91); two horizontal fixing rods (93) stably clamp the shell (101) via arc-shaped clamping portions, and one end of the fixing rod (93) away from the shell (101) is a threaded rod, which passes through the vertical rod (94), and an adjusting nut (92) is installed on the threaded rod extending from the vertical rod (94) to adjust the positions of the two fixing rods (93).

5. The combined determination method of the device for determining the maximum dry density and bearing ratio of rock and soil according to claim 1, characterized in that: The following steps are involved: S1: Take a number of rock and soil samples and air-dry them to constant weight, then test the moisture content of the air-dried rock and soil samples; then spray the air-dried rock and soil samples with different water contents, including rock and soil samples with moisture contents above and below the plastic limit; S2: Apply a corresponding weight (84) to the force-applying end of the lever (81) to lift the hammer (6) to the height position limited by the limit plate (7); place the rock and soil sample processed in S2 into the compaction cylinder (2), and then place the positioning sleeve (4) onto the upper surface of the uncompacted rock and soil sample; remove the weight (84), and the hammer (6) falls simultaneously along the positioning channel (41), completing one compaction; S3: A weight (84) of corresponding weight is applied to the force-applying end of the lever (81) to lift the hammer (6) to the initial height position limited by the limit plate (7), and the rotating disk (5) is rotated to adjust the position of the hammer (6) to be located directly above another positioning channel (41), and the above-mentioned hammer-dropping process is repeated; S4: compacting the rock and soil sample until it is level with the top surface of the compaction cylinder (2) of the second layer, thus completing the compaction of the first layer of rock and soil sample; repeating the above compaction process to complete the compaction of multiple layers of rock and soil sample; S5: After the rock and soil sample is compacted under a certain compaction work, the compaction cylinder (2) and the formed specimen are taken out from the device, demoulded, and the height h, diameter D and mass m of the specimen are measured. The mass m of the water in the seepage tray is weighed. 渗出水 , a probe-type moisture sensor was used to measure the moisture content of the specimen; Calculate dry density; S6: Repeat the above compaction and calculation steps to obtain the moisture content and dry density of multiple groups of rock and soil samples; take the moisture content w as the horizontal axis and the dry density ρ as the horizontal axis. d As the vertical coordinate, draw the dry density-water content relationship curve. The horizontal and vertical coordinates of the highest point in the curve are the optimal water content and maximum dry density of the rock and soil sample. S7: Prepare the test sample according to the optimal moisture content, complete the compaction of the rock and soil sample under a certain compaction work, take out the compaction cylinder (2) and the formed test piece, flatten the top of the test piece, and weigh the mass m2 of the test piece; S8: Remove the broken filter paper on the top of the specimen, replace it with a complete filter paper, and install an adjustable porous plate on it. Add several load weights (84) to the porous plate to make the surface of the specimen as flat as possible during the soaking and expansion process; measure the volume of the specimen before soaking; S9: Place the specimen in a container, add water until the water level covers the top of the specimen, soak it in water, pour out the water on the top, and let it stand to drain; measure the volume of the specimen after expansion and calculate the expansion amount; weigh the weight m3 of the specimen after soaking in water and calculate the changes in the humidity and density of the specimen; S10: Fix the penetration device above the test piece, align the probe (103) so that it is in full contact with the top surface of the test piece; rotate the rocker (105), adjust the pointers of the force measuring pressure gauge (104) to integers, and record the initial reading; rotate the rocker (105) so that the penetration rod (102) is pressed into the test piece at a speed of 1 to 1.25 mm / min, and simultaneously record the reading of the pressure gauge (104); record the rotation amount of the rocker (105) when the pressure gauge (104) is an integer, and calculate the penetration amount by the number of rotations of the rocker (105): l = l r ×R; where l is the penetration; l r is the extension and contraction of the penetration rod when the rocking plate rotates one circle, and R is the number of rotations of the rocking plate; S11: Use unit pressure p as the abscissa, i.e., the penetration load; and penetration l as the ordinate to draw a pl relationship curve. If the initial segment of the curve is concave, it needs to be corrected. To do this, draw a tangent line at the point of variable curvature, and intersect the ordinate at point o', which is the corrected origin. S12: Calculate the material bearing ratio CBR based on the unit pressure and the standard pressure.

6. The combined determination method of the device for determining the maximum dry density and bearing ratio of rock and soil according to claim 5, characterized in that: The dry density is calculated according to the following formula: Among them, ρ d is the dry density of the sample; m is the mass of the sample; m 渗出水 is the mass of water discharged during the compaction process; w is the moisture content of the sample; h is the height of the sample; and D is the diameter of the sample.

7. The combined determination method of the device for determining the maximum dry density and bearing ratio of rock and soil according to claim 5, characterized in that: During the compaction process in S5 or S7, part of the hammers (6) fall 1-2 times, that is, the central hammer (6) does not fall, and only the outer three hammers (6) fall to complete the compaction; or only the central hammer (6) falls to complete the compaction, and the outer three hammers (6) do not fall.

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