Sand and gravel stratum drilling model test platform for drilling tool selection and use method

Abstract

The application provides a sand-pebble stratum drilling model test platform for drill selection and a use method, which comprises a tamping assembly, a driving mechanism, a drilling mechanism, a drill, a drill pipe and a jacking mechanism; the driving mechanism is used for driving the tamping assembly to tamping the sample at high frequency, so that the sample reaches a dense state under the set pressure and vibration conditions; the drilling mechanism is used for controlling the rotation of the drill pipe and the drill; the drill pipe and the drill are arranged directly above the sample; the jacking mechanism is used for forcing the drill to move close to or away from the sample, and then drilling the dense sample; the pressure sensor located below the sample barrel in the model test device of the application excludes the influence of the frictional force of the guiding column on the monitoring in the guiding movement, and since the sample barrel does not move and rotate, the measurement value of the pressure sensor is more stable than that of the traditional pull and pressure sensor which moves together with the lifting platform.

Description

Technical Field

[0001] This invention relates to the field of engineering construction technology, and in particular to a drilling model test platform for sand and gravel formations for drill bit selection and its usage method. Background Technology

[0002] Currently, pile drilling rigs are widely used in the construction engineering field. Their technical characteristics include the ability to excavate large-diameter, long pile holes using rotary drilling, serving foundation treatment, cutoff walls, and foundation pit support projects. When drilling into gravel and sandy strata, due to the high compressive strength of these strata, drilling tools encounter difficulties and significant wear during drilling. Therefore, there is an urgent need to determine the appropriate drilling tools for these strata through tool selection. However, there are tens of thousands of possible combinations of drilling tool structural parameters, and manufacturing and testing all of them is not economically feasible. Model testing primarily functions to study the drilling patterns of drilling tools by drilling in simulated strata using scaled-down tools. This is a relatively economical method for conducting drill tool selection. However, in practical operation, the experimental data obtained from model testing has a large dispersion, making it difficult to achieve the precision needed to distinguish the differences in drilling efficiency among various drilling tools. Specifically, this manifests in the following three shortcomings:

[0003] (1) Inhomogeneity and non-reproducibility of sample preparation. In model tests, sand and gravel are generally used to simulate sand and pebble strata. The test material is evenly sprinkled into the model box and then compacted manually or with a handheld electric tamper. Due to the randomness of human operation, it is impossible to guarantee that the density of the test material in different locations in the model box is consistent, and it is also impossible to ensure that the density of different batches of test material is roughly the same. This results in a large dispersion of the physical and mechanical properties of the prepared samples. The results of this test can reflect that the drilling effect of the prototype drilling tool is roughly consistent with that of the prototype drilling tool, such as the shape of the settlement trough and the soil squeezing effect. However, in the selection of drilling tools, it is necessary to compare the subtle differences in drilling efficiency of various different drilling tools. This requires that the physical and mechanical properties of the samples prepared each time are basically the same, and the physical and mechanical properties of each test at each location are basically the same. Obviously, manual compaction and handheld electric tamping cannot prepare multiple samples with basically the same physical and mechanical properties and good uniformity.

[0004] (2) Discrepancy in drilling pressure monitoring results: Drilling model tests typically use tension / compression sensors placed on top of a rotary motor to monitor pressure. The motor and its supporting platform are heavy, generally exceeding 100 kg, thus requiring a large-range monitoring sensor. However, large-range sensors have relatively low accuracy. The drilling process requires a guide rail for guidance, and sliding friction exists between the guide hole and the guide rail. This sliding friction exhibits a degree of randomness and dispersion. The monitoring value of the tension / compression sensor is the resultant force of the weight of the motor, its supporting platform, the drilling tools, the resistance generated during the pressure test, and the sliding friction between the guide rail and the supporting platform. The randomness of the sliding friction value during drilling leads to instability in the tension / compression sensor monitoring values, affecting the estimation of drilling pressure values.

[0005] (3) Model tests are generally dry drilling without soil removal, which is significantly different from the mud wall protection and soil removal drilling of the prototype drilling tool. This results in a loose soil column forming above the drilling tool after a period of drilling in the model test. The drilling tool needs to overcome the pressure of the soil column on the drilling tool to rotate, resulting in the monitored resistance torque being higher than the theoretical value. On the other hand, since the pressure of the soil column on the drilling tool is opposite to the resistance of the un-drilled strata on the drilling tool, the monitored drilling resistance is lower than the theoretical value. The inaccurate data makes it unusable for drilling tool comparison work. If the model test is designed to be the same as the prototype drilling tool with mud wall protection and soil removal drilling, the complexity of the model test design will be greatly increased. The complex test will have more influencing factors, so the stability of the test results will be greatly reduced. Summary of the Invention

[0006] The purpose of this invention is to provide a drilling model test platform for sand and gravel formations and a method for using it for drill bit selection, so as to solve the technical problems existing in the prior art.

[0007] To solve the above-mentioned technical problems, the present invention provides a drilling model test platform for sand and gravel formations for drill bit selection, which includes a sample preparation device;

[0008] The sample preparation device includes a support frame, and a compaction component, a hammer suspension mechanism, and a drive mechanism installed on the support frame;

[0009] The compaction assembly is positioned directly above the sample;

[0010] The hammer suspension mechanism is used to control the compaction component to move closer to or away from the sample;

[0011] The driving mechanism is used to drive the compaction component to perform high-frequency compaction of the sample, so that the sample reaches a dense state under the set pressure and vibration conditions.

[0012] Furthermore, it also includes a sample container located at the bottom of the support frame for holding the sample.

[0013] Furthermore, it also includes a limiting mechanism, which on the one hand guides the tamping component during its lifting and lowering process to prevent the tamping component from tilting, and on the other hand transfers the tamping energy to the sample to prevent air vibration.

[0014] Furthermore, it also includes a platform that can move longitudinally on the support frame for supporting the lifting and lowering of the limiting mechanism.

[0015] The combination of the compaction component and the driving mechanism is similar to a tamping structure. The driving mechanism drives the working surface of the compaction component to perform high-frequency compaction on the sample surface, and the driving mechanism generates periodic compression motion so that the loose sample achieves the effect of vibration compaction.

[0016] Preferably, the compaction assembly includes a tamping plate and a tamping hammer;

[0017] The tamping plate is positioned above the sample to ensure close contact with the loose sample.

[0018] The tamping hammer is positioned on the upper side of the tamping plate to control the close contact between the tamping plate and the sample, thereby enabling the sample to achieve a higher degree of compaction.

[0019] For samples of different depths and hardness, in order to ensure preparation efficiency, the bottom area of ​​the tamping hammer is increased (decreased) and the height of the tamping hammer is increased (decreased) to increase the impact energy per unit area under the same volume, so as to achieve the optimal vibration compaction effect.

[0020] Furthermore, the tamping plate is a disc structure with the same diameter as the inner diameter of the sample barrel. The tamping plate is in complete contact with the sample surface inside the sample barrel, and the pressure and vibration force borne by each position on the sample surface are basically the same. Therefore, the prepared sample has good uniformity. In addition, for different batches of loose samples with the same particle size distribution, since they are all compacted under the same pressure, vibration frequency, and vibration time conditions, the physical and mechanical properties of the samples produced by this method are basically the same.

[0021] Preferably, the limiting mechanism includes a limiting block, a slider, and a connecting rod;

[0022] The limiting block is disposed on the upper side of the platform, and a slot is provided inside the limiting block. A slider is slidably disposed in the slot of the limiting block.

[0023] The connecting rod is vertically arranged, with its bottom end connected to the drive mechanism and its top end passing through the platform and extending through the through hole inside the limiting block to the slot and connect with the slider. The connecting rod moves longitudinally within the limiting block through the sliding connection between the slider and the slot.

[0024] During operation, the hammer suspension mechanism drives the compaction assembly to descend into the sample barrel, ensuring that the tamping plate is firmly attached to the loose sample. The drive mechanism then drives the hammer to compact the sample at high frequency. As the sample is continuously compacted, the hammer descends continuously. To prevent the hammer from failing to vibrate the sample due to the connecting rod descending to the lowest point of the limit block, the hammer suspension mechanism continuously controls the platform to descend and moves the limit mechanism downward. Simultaneously, as the hammer descends, the connecting rod moves to the middle or upper part of the slot via the slider. This ensures that the energy of the drive mechanism is transferred to the sample to the maximum extent, improving the preparation efficiency of dense samples.

[0025] Furthermore, the hammer suspension mechanism includes a first motor and a first transmission mechanism;

[0026] The first transmission mechanism is existing technology, and a worm gear transmission pair is preferred.

[0027] Furthermore, the driving mechanism is existing technology, and is preferably a vibratory machine, vibrator, etc.

[0028] Furthermore, it also includes a top platform mounted on the support frame for the installation of the hammer suspension mechanism.

[0029] Furthermore, it also includes guide column support frames and guide columns disposed on both sides of the support frame, with the bottom of the guide column disposed on the guide column support frame and the top of the guide column connected to the top platform.

[0030] Furthermore, the platform has holes at both ends that match the guide posts, and the platform is slidably connected to the guide posts through these holes to guide the platform.

[0031] Furthermore, it also includes drilling equipment;

[0032] The drilling device includes a drilling mechanism, a drill string, a drill rod, and a jacking mechanism;

[0033] The drilling mechanism is used to control the rotation of the drill rod and drill string;

[0034] The drill rod and drill bit are positioned directly above the sample;

[0035] The jacking mechanism is used to force the drill bit to approach or move away from the sample, thereby performing drilling operations on the dense sample.

[0036] Furthermore, the jacking mechanism pushes the platform downward, causing the drill rod and drill bit to move into the sample barrel. The drilling mechanism is activated, controlling the rotation of the drill rod and drill bit. As the drill bit descends, the rotary drilling operation is completed.

[0037] Furthermore, it also includes a monitoring mechanism, which is located on the upper side of the drilling mechanism and the lower side of the sample barrel;

[0038] The monitoring mechanism includes a dynamic torque and speed sensor, a tension and compression sensor, and a pressure sensor.

[0039] The dynamic torque and speed sensor is disposed between the drilling mechanism and the drill rod to monitor the drill rod speed and torque.

[0040] The first tension and compression sensor is installed between the jacking mechanism and the drilling mechanism to monitor the combined force of the weight of the platform, the drilling mechanism, the dynamic torque and speed sensor, the drill rod, the drill tool, the resistance of the sample in the sample bucket to the drill tool, and the sliding friction force on both ends of the platform. By judging the change of the combined force, the change of the resistance of the sample in the sample bucket to the drill tool can be inferred.

[0041] The pressure sensor is located at the bottom of the sample barrel and is used to monitor the downward pressure exerted by the sample barrel on the pressure sensor, thereby allowing the resistance of the sample barrel to the drill bit to be inferred.

[0042] Since the sample bucket has no displacement, it remains in equilibrium vertically under the influence of gravity, the supporting force from the pressure sensor, and the downward pressure from the drill bit. The supporting force from the pressure sensor and the downward pressure from the sample bucket on the pressure sensor are an action-reaction pair, equal in magnitude and opposite in direction. Therefore, by monitoring the change in the downward pressure from the sample bucket on the pressure sensor, we can observe the change in the resistance of the sample inside the bucket to the drill bit, and measure the drilling resistance value using formula ①.

[0043] F 阻1 =F 支 -G 总1 ①

[0044] G 总1 =(M 桶 +M 样 )g (g=9.8N / kg) ②

[0045] In the formula:

[0046] F 阻1 The value representing the drilling resistance of this invention is the downward pressure exerted by the drill bit on the sample bucket, expressed in N.

[0047] F 支 This represents the value measured by the pressure sensor supporting the sample barrel during the drilling process of this invention, in N;

[0048] G 总1 This represents the total weight of the sample container and the sample, expressed in N.

[0049] M 桶 +M 样 The total mass of the sample container and the sample measured in steps S10-S70 is used to calculate G using formula ②. 总1 .

[0050] Preferably, the pressure sensor located below the sample barrel is more accurate in its calculation because it is not affected by the sliding friction of the moving platform. It can be mutually corrected by the changes in the monitoring values ​​of the tension and compression sensors and the pressure sensor to determine the change in the resistance value borne by the drill bit.

[0051] Furthermore, it also includes a wire-type displacement gauge mounted on a support frame, wherein the end of the monitoring line of the wire-type displacement gauge is connected to the platform for monitoring the displacement values ​​of the platform and the drilling tool.

[0052] Furthermore, the drilling mechanism includes a second motor and a second transmission mechanism;

[0053] The second transmission mechanism is existing technology, and is preferably a bevel gear transmission pair.

[0054] Furthermore, it also includes a counterweight set on the surface of the sample for pressurizing the sample, so that the sample can reach the same stress state as the prototype drill bit.

[0055] The counterweight also has a through hole in the middle to ensure that the drill can move downwards into the sample to complete the drilling work.

[0056] Furthermore, the output shaft of the dynamic torque-speed sensor is connected to the input shaft of the drill pipe.

[0057] Furthermore, the input shaft of the dynamic torque and speed sensor is connected to the output shaft of the drilling mechanism.

[0058] Furthermore, it also includes a first fixing frame, which is disposed at the bottom of the mobile platform;

[0059] The dynamic torque and speed sensor is fixedly installed inside the first mounting bracket.

[0060] Furthermore, it also includes a control system that can independently adjust the rotation and jacking of the drill bit. When the control system controls the jacking mechanism, it can start and stop the jacking and change the jacking speed at any time. When it controls the drilling mechanism of the drill bit, it can realize its forward (clockwise) and reverse (counterclockwise) rotation and stop, and can adjust its speed at any time.

[0061] Furthermore, the jacking mechanism has the same structure as the ramming hammer suspension mechanism.

[0062] Furthermore, it also includes a jack pad, a jack, and a jack top plate, wherein the jack pad is disposed above the compacted sample and is in close contact with it; the jack top plate is disposed on the top of the sample barrel; and several jacks are evenly distributed along the circumferential direction of the jack pad.

[0063] Furthermore, the jack is connected to a hydraulic pump, which provides the jack with a pushing force.

[0064] Furthermore, the top plate of the jack is fixed to the sample barrel by bolts, screws and other locking devices.

[0065] Furthermore, when higher test stress is required, the jack is pressurized in advance by a hydraulic pump. The jack plate above the jack restricts the upward pushing space of the jack. The jack pressurizes the sample by pushing the jack pad below it, so that the sample can reach the expected stress state of larger compressive stress.

[0066] Furthermore, it also includes a second tension / compression sensor, which is installed between the dynamic torque / speed sensor and the drill pipe to monitor the combined force of the weight of the drill pipe and drill string and the drilling resistance, thereby inferring the drilling resistance.

[0067] The force measured by the second tension / compression sensor is the resultant force of the drill pipe, drill string, and drilling resistance. Since the drill pipe and drill string are standard parts, their weight values ​​are fixed and will not change, calculated according to formula ④. The resistance value can be calculated according to formula ③.

[0068] F 阻2 =F 合 -G 总2 ③

[0069] G 总2 =(M 杆 +M 头 )g (g=9.8N / kg) ④

[0070] The F mentioned 阻2 The value represents the drilling resistance of this invention, expressed in N.

[0071] The F mentioned 合 The value measured by the No. 2 tension and compression sensor during the drilling process of this invention is the resultant force of the drill pipe, drill string, and drilling resistance, in N.

[0072] The G mentioned 总2 This is the sum of the weight of the drill pipe and drill string, expressed in N.

[0073] In addition, since there is no interference from the sliding friction force caused by the moving platform, the calculated value is more accurate. The changes in the resistance value borne by the drill bit can be determined by mutual correction through the monitoring values ​​of the No. 1 tension and compression sensor, the No. 2 tension and compression sensor, and the pressure sensor.

[0074] Furthermore, it also includes a second fixing frame, which is disposed below the first fixing frame and encloses the second tension / compression sensor inside.

[0075] The second fixing frame can be a separate component or it can be integrally formed with the first fixing frame.

[0076] Furthermore, it also includes a rotating conductive slip ring, which is disposed at the bottom of the second fixed frame and is a 360° rotating conductive device to prevent the data transmission line of the second tension and compression sensor from getting tangled on the drill rod.

[0077] Furthermore, the rotating conductive slip ring has a through hole in the center that is the same as the outer diameter of the drill rod, and the drill rod passes through the through hole;

[0078] Furthermore, the input shaft of the second tension / compression sensor is connected to the output shaft of the dynamic torque / speed sensor.

[0079] Furthermore, the output shaft of the second pressure sensor is connected to the input shaft of the drill rod.

[0080] Preferably, the rotating conductive slip ring comprises a stator and a rotor, wherein the stator is disposed on the outer ring and fixedly connected to the second fixed frame;

[0081] The stator only moves in the vertical direction, and its moving speed is the same as that of the platform.

[0082] The rotor is located in the inner ring and rotates in the direction of the drill rod about its central axis.

[0083] The data line inside the rotor is connected to the data transmission line of the second tension / compression sensor;

[0084] The data signal transmission between the data lines inside the rotor and the data lines inside the stator is accomplished through the sliding contact transmission of the conductive ring;

[0085] It also includes a data acquisition device, which is connected to the test platform and to the data lines inside the stator.

[0086] Furthermore, the method for using the sand and gravel formation drilling model test platform for drill bit selection includes a sample preparation method, specifically comprising the following steps:

[0087] Step S1: Measure the particle size distribution of the prototype drilling formation. The particle size model of the prototype drilling formation is a multiple of the set geometric similarity constant of the particle size used in the test. After preparing the corresponding particle aggregate sample required for the model test, divide the particle aggregate sample into three parts and measure and record the mass of the empty sample bucket.

[0088] Step S2: Slowly fill any sample into the sample container; smooth the sample surface, and then tap the sample container wall several times to make the sample sink.

[0089] Step S3: Place the sample container directly below the ramming plate and fix it in place;

[0090] Step S4: Start the jacking mechanism to move the vibratory motor, steel rammer, and rammer plate downwards, so that the rammer plate is in close contact with the sample. Close the jacking mechanism, vibrate for 6 minutes, and then start the jacking mechanism again to lift the vibratory motor.

[0091] Step S5: Repeat steps S2-S4 to vibrate and compact the second and third layers of the sample.

[0092] Step S6: Place the straight steel bar at the diameter position of the sample barrel, measure the height of the sample after vibration, record and calculate the sample height;

[0093] Step S7: Measure and record the mass of the sample container and the sample. Subtract the mass of the sample container to get the mass of the sample. Calculate the density of the dense sample.

[0094] Furthermore, it also includes a method of calculating the difference between the resistance torque and resistance by performing two consecutive drilling operations, which specifically includes the following steps:

[0095] Step S10: Using this test platform, the prepared compacted sample is drilled for the first time. The drilling mechanism controls the rotation of the drill rod and drill string, while the jacking mechanism controls its downward movement, allowing it to continuously drill into the compacted sample until it reaches the bottom. Then, the drill string is pulled up to the top of the sample. During this process, the resistance F at different drilling heights is recorded. 阻A and resistance torque T 转A The value;

[0096] Step S20: Conduct a second drilling test and record the resistance F at different drilling heights. 阻B and resistance torque T 转B The value;

[0097] Step S30: During the second drilling process, the drilled soil is a loose sample produced from the soil from the first drilling. The drill string also bears the pressure and resistance of the loose soil column above it. Formula ⑤ is used to calculate the difference between the drill string's torque and resistance during the first drilling at the same depth and the drill string's torque and resistance during the second drilling.

[0098] F 差 =F 阻A -F 阻B ⑤

[0099] T 差 =T 转A -T 转B ⑥

[0100] In the formula: F 差 This represents the difference in resistance between the two drilling operations;

[0101] T 差 This represents the difference in resistance torque between the two drilling processes;

[0102] F 阻A This represents the drilling resistance value during the first drilling operation, in N, calculated according to formula ① or formula ③.

[0103] F 阻B This represents the drilling resistance value during the second drilling operation, in N, calculated according to formula ① or formula ③.

[0104] T 转A The torque of the drill string during the first drilling operation is represented by N·m and is monitored by a dynamic torque-speed sensor.

[0105] T 转B The torque of the drill string during the second drilling operation is represented by N·m and is monitored by a dynamic torque-speed sensor.

[0106] Step S40: Since the resistance and torque caused by the overlying loose soil column are the same at the same location during both drilling operations, calculating the difference can offset the influence of the overlying loose soil column on the calculated drilling resistance and torque of the model test. This avoids inaccurate calculations caused by inconsistencies between the dry drilling and non-soil removal drilling methods of the model test and the mud circulation and soil removal drilling methods of the prototype drilling tool. This difference represents the additional resistance and torque required to drill a compacted sample relative to drilling a loose sample. This difference is consistent with the resistance and torque experienced by the drilling tool during mud circulation and soil removal drilling of the prototype drilling tool, and is used to compare the differences in resistance and torque required by different drilling tools to drill a compacted sample.

[0107] By adopting the above technical solution, the present invention has the following beneficial effects:

[0108] (1) The sample preparation device in this invention can precisely control the pressure, vibration frequency and amplitude through surface vibration compaction method, so that each prepared sample has the same physical and mechanical properties. Each sample has the same physical and mechanical properties at each position, which can be used to compare the drilling efficiency of different drilling tools.

[0109] (2) By setting a pressure sensor under the sample barrel in this invention, the influence of friction between the sample barrel and the guide column on the monitoring during the guide movement is eliminated. The sample barrel does not move or rotate, and the measurement value is more stable than that of the traditional tension and pressure sensor that moves together with the lifting platform.

[0110] (3) The method of calculating the resistance torque and resistance difference by drilling twice in succession in this invention can avoid the problem of inaccurate calculation caused by the inconsistency between the dry drilling and non-soil removal drilling method of the model test and the mud circulation and soil removal drilling method of the prototype drilling tool.

[0111] Because this invention can provide more accurate and stable values ​​of resistance torque and resistance during the drilling process, it is used for drill bit selection and comparison work where the stability of monitoring data is more important. Attached Figure Description

[0112] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0113] Figure 1 This is a front cross-sectional view of the sample preparation device provided in Embodiment 1 of the present invention;

[0114] Figure 2 This is a frontal cross-section of the sample preparation device provided in Embodiment 1 of the present invention when the sample preparation work is completed;

[0115] Figure 3 This is a frontal cross-section of the simulation test platform provided in Embodiment 2 of the present invention;

[0116] Figure 4 This is a front cross-sectional view of the drilling test apparatus provided in Embodiment 4 of the present invention;

[0117] Figure 5 This is a front cross-sectional view of the sample barrel of the drilling test device provided in Embodiment 3 of the present invention;

[0118] Figure 6 This is a top cross-sectional view of the rotating conductive slip ring of the drilling test apparatus provided in Embodiment 3 of the present invention;

[0119] Figure 7 This is a diagram illustrating the method of using the drilling test apparatus provided in Embodiment 1 of the present invention.

[0120] Figure label:

[0121] 1-Support frame, 2-Hammer suspension mechanism, 3-Drive mechanism, 4-Sample bucket, 5-Sample, 6-Platform, 7-Hammer plate, 8-Hammer, 9-Limiting block, 10-Slider, 11-Connecting rod, 12-Top platform, 13-Drilling mechanism, 14-Drill tool, 15-Drill rod, 16-Jumping mechanism, 17-Dynamic torque and speed sensor, 18-First tension and compression sensor, 19-Wire displacement gauge, 20-Counterweight, 21-Pressure sensor, 22-First fixed frame, 23-Jack pad, 24-Jack, 25-Jack top plate, 26-Hydraulic pump, 27-Second tension and compression sensor, 28-Second fixed frame, 29-Rotating conductive slip ring, 30-Stator, 31-Rotor. Detailed Implementation

[0122] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0123] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0124] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0125] The present invention will be further explained below with reference to specific embodiments.

[0126] Example 1

[0127] like Figure 1-2 As shown in the figure, the sand and gravel formation drilling model test platform for drill bit selection provided in this embodiment includes a sample preparation device;

[0128] The sample preparation device includes a support frame 1, and a compaction component, a hammer suspension mechanism 2, and a drive mechanism 3 installed on the support frame 1;

[0129] The compaction assembly is positioned directly above the sample 5;

[0130] The hammer suspension mechanism 2 is used to control the compaction component to move closer to or away from the sample 5;

[0131] The driving mechanism 3 is used to drive the compaction component to perform high-frequency compaction on the sample 5, so that the sample 5 reaches a dense state under the set pressure and vibration conditions.

[0132] More preferably, this embodiment also includes a limiting mechanism, which on the one hand guides the tamping component during the lifting process to prevent the tamping component from tilting, and on the other hand transfers the tamping energy to the sample 5 to prevent air vibration.

[0133] This embodiment also includes a sample bucket 4 located at the bottom of the support frame 1 for holding the sample 5.

[0134] Furthermore, it also includes a platform 6 that is longitudinally movable on the support frame 1, used for supporting the lifting and lowering of the limiting mechanism.

[0135] The combination of the compaction component and the drive mechanism 3 is similar to a tamping structure. The drive mechanism 3 drives the working surface of the compaction component to perform high-frequency compaction on the surface of the sample 5. The drive mechanism 3 generates periodic compression motion so that the loose sample achieves the effect of vibration compaction.

[0136] Preferably, the compaction assembly includes a tamping plate 7 and a tamping hammer 8;

[0137] The tamping plate 7 is positioned above the sample 5 and is used to closely adhere to the loose sample 5.

[0138] The tamping hammer 8 is disposed on the upper side of the tamping plate 7 and is used to control the tamping plate 7 to be in close contact with the sample 5, so that the sample 5 obtains a higher degree of compaction.

[0139] For samples of different depths and hardness, in order to ensure preparation efficiency, the bottom area of ​​the tamping hammer 8 is increased (decreased) and the height of the tamping hammer 8 is increased (decreased) to increase the impact energy per unit area under the same volume, so as to achieve the optimal vibration compaction effect.

[0140] Furthermore, the tamping plate 7 is a disc structure with the same diameter as the inner diameter of the sample barrel 4. The tamping plate 7 is completely in close contact with the sample surface inside the sample barrel 4, and the pressure and vibration force borne by each position on the sample surface are basically the same. Therefore, the prepared sample has good uniformity. In addition, for different batches of loose samples with the same particle size distribution, since they are all compacted under the same pressure, vibration frequency, and vibration time conditions, the physical and mechanical properties of the samples produced by this method are basically the same.

[0141] More preferably, the limiting mechanism includes a limiting block 9, a slider 10, and a connecting rod 11;

[0142] The limiting block 9 is disposed on the upper side of the platform 6. A slot is provided inside the limiting block 9, and a slider 10 is slidably disposed in the slot of the limiting block 9.

[0143] The connecting rod 11 is vertically arranged. The bottom end of the connecting rod 11 is connected to the driving mechanism 3. The top end of the connecting rod 11 passes through the platform 6 and extends through the through hole inside the limiting block 9 to the slot and connect with the slider 10. The connecting rod 11 moves longitudinally within the limiting block 9 through the sliding connection between the slider 10 and the slot.

[0144] Working principle: During operation, the hammer suspension mechanism 2 drives the compaction component to descend into the sample barrel 4, so that the tamping plate 7 and the loose sample 5 are firmly attached. The drive mechanism 3 drives the hammer 8 to compact the sample 5 at high frequency. As the sample 5 is continuously compacted, the sample 5 is compressed and the hammer 8 continues to descend. In order to prevent the connecting rod 11 from descending to the lowest point of the limit block 9, which would cause the hammer 8 to be unable to vibrate the sample and thus cause empty vibration, the hammer suspension mechanism 2 controls the platform 6 to descend at any time and drives the limit mechanism to move down. At the same time as the hammer 8 descends, the connecting rod 11 moves to the middle or upper part of the slot through the slider 10. This ensures that the energy of the drive mechanism 3 is transferred to the sample to the maximum extent, which improves the preparation efficiency of the dense sample.

[0145] Furthermore, the hammer suspension mechanism 2 includes a first motor and a first transmission mechanism;

[0146] The first transmission mechanism is existing technology, and a worm gear transmission pair is preferred.

[0147] Furthermore, the driving mechanism 3 is existing technology, and is preferably a vibratory machine, vibrator, etc.

[0148] Furthermore, it also includes a top platform 12 set on the support frame 1 for the installation of the hammer suspension mechanism 2.

[0149] Furthermore, it also includes guide column support frames and guide columns disposed on both sides of the support frame 1, with the bottom of the guide column disposed on the guide column support frame and the top of the guide column connected to the top platform.

[0150] Furthermore, the platform 6 has holes at both ends that match the guide posts. The platform is slidably connected to the guide posts through these holes, which serves to guide the platform 6.

[0151] Furthermore, the method of using the test platform includes a sample preparation method, specifically comprising the following steps:

[0152] Step S1: Measure the particle size distribution of the prototype drilling formation. The particle size model of the prototype drilling formation is a multiple of the set geometric similarity constant of the particle size used in the test. After preparing the corresponding particle aggregate sample required for the model test, divide the particle aggregate sample into three parts and measure and record the mass of the empty sample bucket.

[0153] Step S2: Slowly fill any sample into the sample container; smooth the sample surface, and then tap the sample container wall several times to make the sample sink.

[0154] Step S3: Place the sample container directly below the ramming plate and fix it in place;

[0155] Step S4: Start the jacking mechanism to move the vibratory motor, steel rammer, and rammer plate downwards, so that the rammer plate is in close contact with the sample. Close the jacking mechanism, vibrate for 6 minutes, and then start the jacking mechanism again to lift the vibratory motor.

[0156] Step S5: Repeat steps S2-S4 to vibrate and compact the second and third layers of the sample.

[0157] Step S6: Place the straight steel bar at the diameter position of the sample barrel, measure the height of the sample after vibration, record and calculate the sample height;

[0158] Step S7: Measure and record the mass of the sample container and the sample. Subtract the mass of the sample container to get the mass of the sample. Calculate the density of the dense sample.

[0159] The sample preparation device in this embodiment can precisely control the pressure, vibration frequency, and amplitude through surface vibration compaction, so that each prepared sample has basically the same physical and mechanical properties. Each sample has basically the same physical and mechanical properties at each position, which can be used to compare the drilling efficiency of different drilling tools.

[0160] Example 2

[0161] This embodiment is basically the same as embodiment 1, except that:

[0162] This embodiment also includes a drilling device;

[0163] The drilling device includes a drilling mechanism 13, a drill string 14, a drill rod 15, and a jacking mechanism 16;

[0164] The drilling mechanism 13 is used to control the rotation of the drill rod 15 and the drill string 14;

[0165] The drill rod 15 and drill tool 14 are positioned directly above the sample 5;

[0166] The jacking mechanism 16 is used to force the drill bit 14 to approach or move away from the sample 5, thereby drilling the dense sample.

[0167] Furthermore, the jacking mechanism 16 pushes the platform 6 downward, causing the drill rod 15 and drill bit 14 to move into the sample barrel 4. The drilling mechanism 3 is activated, controlling the rotation of the drill rod 15 and drill bit 14. The drill bit 14 descends while completing the rotary drilling operation.

[0168] More preferably, it also includes a monitoring mechanism, which is disposed on the upper side of the drilling mechanism and the lower side of the sample barrel 4;

[0169] The monitoring mechanism includes a dynamic torque and speed sensor 17, a tension and compression sensor 18, and a pressure sensor 21.

[0170] The dynamic torque and speed sensor 17 is disposed between the drilling mechanism 13 and the drill rod 15 to monitor the speed and torque of the drill rod 15.

[0171] The first tension and compression sensor 18 is located between the jacking mechanism 16 and the drilling mechanism 13. It is used to monitor the combined force of the weight of the platform 6, the drilling mechanism 13, the dynamic torque and speed sensor 17, the drill rod 15, the drill tool 14, the resistance of the sample 5 in the sample bucket 4 to the drill tool 14, and the sliding friction force at both ends of the platform 6. By judging the change of the combined force, the change of the resistance of the sample in the sample bucket 4 to the drill tool can be inferred.

[0172] The pressure sensor 21 is located at the bottom of the sample barrel 4 and is used to monitor the downward pressure of the sample barrel on the pressure sensor 21, thereby inferring the resistance of the sample barrel 4 to the drill bit 14.

[0173] Since the sample bucket 4 has no displacement, it remains in equilibrium vertically under the influence of gravity, the supporting force from the pressure sensor 21, and the downward pressure from the drill string 14. The supporting force from the pressure sensor 21 and the downward pressure from the sample bucket 4 on the pressure sensor 21 are an action-reaction pair, equal in magnitude and opposite in direction. Therefore, by monitoring the change in the downward pressure from the sample bucket 4 on the pressure sensor 21, the change in the resistance of the sample inside the sample bucket 4 to the drill string 14 can be observed, and the drilling resistance value can be measured using formula ①.

[0174] F 阻1 =F 支 -G 总1 ①

[0175] G 总1 =(M 桶 +M 样 )g (g=9.8N / kg) ②

[0176] In the formula:

[0177] F 阻1 The value representing the drilling resistance of this invention is the downward pressure exerted by the drill bit on the sample bucket, expressed in N.

[0178] F 支 This represents the value measured by the pressure sensor supporting the sample barrel during the drilling process of this invention, in N;

[0179] G 总1This represents the total weight of the sample container and the sample, expressed in N.

[0180] M 桶 +M 样 The total mass of the sample container and the sample measured in steps S10-S70 is used to calculate G using formula ②. 总1 .

[0181] Preferably, the pressure sensor 21 below the sample barrel 4 in the test platform of this embodiment eliminates the influence of friction with the guide column on the monitoring during the guide movement. Since the sample barrel 4 does not move or rotate, the measurement value is more stable than that of the traditional tension and pressure sensors that move together with the lifting platform. At the same time, the change in the resistance value borne by the drill bit 14 can be determined by mutual correction of the monitoring value changes of the first tension and pressure sensor 18 and the pressure sensor 21.

[0182] Furthermore, this embodiment also includes a wire displacement gauge 19 mounted on the support frame 1. The end of the monitoring line of the wire displacement gauge 19 is connected to the platform 6 and is used to monitor the displacement values ​​of the platform 6 and the drill bit 14.

[0183] Furthermore, the drilling mechanism 13 includes a second motor and a second transmission mechanism;

[0184] The second transmission mechanism is existing technology, and is preferably a bevel gear transmission pair.

[0185] Furthermore, this embodiment also includes a counterweight 20 disposed on the surface of the sample 5 for pressurizing the sample 5, so that the sample 5 can reach the same stress state as the prototype drill bit.

[0186] The counterweight 20 also has a through hole in the middle to ensure that the drill bit 14 can move downwards into the sample 4 to complete the drilling work.

[0187] Furthermore, the output shaft of the dynamic torque and speed sensor 17 is connected to the input shaft of the drill rod 15.

[0188] Furthermore, the input shaft of the dynamic torque and speed sensor 17 is connected to the output shaft of the drilling mechanism 13.

[0189] Furthermore, it also includes a first fixing frame 22, which is disposed at the bottom of the platform 6;

[0190] The dynamic torque and speed sensor 17 is fixedly installed inside the first fixing frame 22.

[0191] Furthermore, this embodiment also includes a control system that can independently adjust the rotation and jacking of the drill string 14. When the control system controls the hammer suspension mechanism 2 (jacking mechanism 16), it can start and stop the jacking and change the jacking speed at any time. When it controls the drilling mechanism 13 of the drill string 14, it can realize its forward (clockwise) and reverse (counterclockwise) rotation and stop, and can adjust its rotation speed at any time.

[0192] Furthermore, the jacking mechanism 16 has the same structure as the ram suspension mechanism 2.

[0193] Example 3

[0194] In the prototype drilling process, the drill bit uses mud slurry for wall protection and soil removal. This means that during drilling, loose soil generated during drilling is removed to the surface, while mud is injected into the borehole to generate hydrostatic pressure on the borehole wall, preventing collapse. The drilling resistance of the drill bit is mainly due to the resistance exerted by the hard strata below it; the mud only provides a small amount of buoyancy. In the model test, dry drilling without soil removal is generally used, meaning no mud is used and loose soil generated during drilling is not removed. This results in a loose soil column forming above the drill bit, requiring the drill bit to overcome the pressure of the soil column to rotate, leading to inconsistencies between the test results and the prototype drilling test results. Therefore, this embodiment provides a method for calculating the difference between the drag torque and resistance by performing two consecutive drilling operations. Please refer to [reference needed]. Figure 7 This solves the problem of inaccurate calculations caused by the inconsistency between the dry drilling and non-soil removal drilling methods in the model test and the mud circulation and soil removal drilling methods in the prototype drilling tool. Specifically, it includes the following steps:

[0195] Step S10: Using this test platform, the prepared compacted sample is drilled for the first time. The drilling mechanism controls the rotation of the drill rod and drill string, while the jacking mechanism controls its downward movement, allowing it to continuously drill into the compacted sample until it reaches the bottom. Then, the drill string is pulled up to the top of the sample. During this process, the resistance F at different drilling heights is recorded. 阻A and resistance torque T 转A The value;

[0196] Step S20: Conduct a second drilling test and record the resistance F at different drilling heights. 阻B and resistance torque T 转B The value;

[0197] Step S30: During the second drilling process, the drilled soil is a loose sample produced from the soil from the first drilling. The drill string also bears the pressure and resistance of the loose soil column above it. Formula ⑤ is used to calculate the difference between the drill string's torque and resistance during the first drilling at the same depth and the drill string's torque and resistance during the second drilling.

[0198] F差 =F 阻A -F 阻B ⑤

[0199] T 差 =T 转A -T 转B ⑥

[0200] In the formula: F 差 This represents the difference in resistance between the two drilling operations;

[0201] T 差 This represents the difference in resistance torque between the two drilling processes;

[0202] F 阻A This represents the drilling resistance value during the first drilling operation, in N, calculated according to formula ① or formula ③.

[0203] F 阻B This represents the drilling resistance value during the second drilling operation, in N, calculated according to formula ① or formula ③.

[0204] T 转A The torque of the drill string during the first drilling operation is represented by N·m and is monitored by the dynamic torque and speed sensor 7.

[0205] T 转B The torque of the drill string during the second drilling operation is represented by N·m and is monitored by the dynamic torque and speed sensor 7.

[0206] Step S40: Since the resistance and torque caused by the overlying loose soil column are the same at the same location during both drilling operations, calculating the difference can offset the influence of the overlying loose soil column on the calculated drilling resistance and torque of the model test. This avoids inaccurate calculations caused by inconsistencies between the dry drilling and non-soil removal drilling methods of the model test and the mud circulation and soil removal drilling methods of the prototype drilling tool. This difference represents the additional resistance and torque required to drill a compacted sample relative to drilling a loose sample. This difference is consistent with the resistance and torque experienced by the drilling tool during mud circulation and soil removal drilling of the prototype drilling tool, and is used to compare the differences in resistance and torque required by different drilling tools to drill a compacted sample.

[0207] Example 4

[0208] This embodiment is basically the same as embodiment 2, except that:

[0209] This embodiment is used for model tests with various similarity ratios. For some physical tests with high stress similarity ratios, when simulating drilling into deeper strata, the test specimen needs to withstand high compressive stress. However, the compressive stress that the counterweight can provide is relatively limited. Please refer to [the relevant documentation]. Figure 5This embodiment includes a jack pad 23, a jack 24, and a jack top plate 25. The jack pad 23 is placed above and in close contact with the compacted sample. The jack top plate 25 is placed on the top of the sample barrel 4. Several jacks 24 are evenly distributed along the circumferential direction of the jack pad 23.

[0210] Furthermore, the jack 24 is connected to the hydraulic pump 26, and the hydraulic pump 26 provides the jack 24 with a pushing force.

[0211] Furthermore, the jack top plate 25 is fixed to the sample barrel 4 by bolts, screws and other locking devices.

[0212] Furthermore, when a higher test stress is required, the hydraulic pump 26 pressurizes the jack 24 in advance. The jack plate 25 above the jack 24 restricts the upward pushing space of the jack 24. The jack 24 pressurizes the sample 5 by pushing the jack pad 23 below it, so that the sample can reach the expected stress state of larger compressive stress.

[0213] Example 5

[0214] This embodiment is basically the same as embodiment 2, except that:

[0215] Because the method of monitoring drill resistance via the pressure sensor 21 below the sample barrel is an indirect measurement method, its accuracy is not as good as direct measurement. Figure 4 As shown, this embodiment also includes a second tension / compression sensor 27, which is disposed between the dynamic torque / speed sensor 17 and the drill pipe 15. It is used to monitor the resultant force of the weight of the drill pipe 15 and the drill string 14 and the drilling resistance, and thereby infer the drilling resistance.

[0216] The force measured by the second tension / compression sensor 27 is the resultant force of the drill pipe, drill string, and drilling resistance. Since the drill pipe and drill string are standard parts, their weight values ​​are fixed and calculated according to formula ④, and will not change. The resistance value can be calculated according to formula ③.

[0217] F 阻2 =F 合 -G 总2 ③

[0218] G 总2 =(M 杆 +M 头 )g (g=9.8N / kg) ④

[0219] The F mentioned 阻2 The value represents the drilling resistance of this invention, expressed in N.

[0220] The F mentioned 合The value measured by the No. 2 tension and compression sensor during the drilling process of this invention is the resultant force of the drill pipe, drill string, and drilling resistance, in N.

[0221] The G mentioned 总2 This is the sum of the weight of the drill pipe and drill string, expressed in N.

[0222] In addition, since there is no interference from the platform on the sliding friction force, the calculated value is more accurate. The changes in the resistance value borne by the drill bit can be determined by mutual correction through the monitoring values ​​of the No. 1 tension and compression sensor, the No. 2 tension and compression sensor, and the pressure sensor.

[0223] This embodiment and Embodiment 4 provide two similarity ratio test schemes, which can basically ensure that all physical quantities meet the mechanical and kinematic similarity ratio criteria, and the calculated values ​​are more accurate.

[0224] Furthermore, this embodiment also includes a second fixing frame 28, which is disposed on the lower side of the first fixing frame 22, and the second fixing frame 28 encloses the second tension and compression sensor 27 inside.

[0225] The second fixing frame 28 can be an independent component or it can be integrally formed with the first fixing frame 22.

[0226] Preferably, this embodiment also includes a rotating conductive slip ring 29, which is disposed at the bottom of the second fixing frame 28 and is a 360° rotating conductive device to prevent the data transmission line of the second tension and compression sensor 27 from getting tangled on the drill rod 15.

[0227] Furthermore, the rotating conductive slip ring 29 has a through hole in the center with the same outer diameter as the drill rod 15, and the drill rod 15 passes through the through hole;

[0228] Furthermore, the input shaft of the second tension / compression sensor 27 is connected to the output shaft of the dynamic torque / speed sensor 17.

[0229] Furthermore, the output shaft of the second pressure sensor 27 is connected to the input shaft of the drill rod 15.

[0230] Preferably, please refer to Figure 6 The rotating conductive slip ring 29 includes two parts: a stator 30 and a rotor 31. The stator 30 is disposed on the outer ring and fixedly connected to the second fixed frame 28.

[0231] The stator 30 only moves in the vertical direction, and its moving speed is the same as that of the platform 6.

[0232] The rotor 31 is disposed in the inner ring and rotates with the drill rod 15 around its central axis.

[0233] The data line inside the rotor 31 is connected to the data transmission line of the second tension / compression sensor 27;

[0234] The data signal transmission between the data lines inside the rotor 31 and the data lines inside the stator is completed through the sliding contact transmission of the conductive ring.

[0235] This embodiment also includes a data acquisition device, which is connected to the test platform and to the data lines inside the stator.

[0236] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A drilling model test platform for gravel and sand formations used for drill bit selection, characterized in that, Includes sample preparation equipment; The sample preparation device includes a support frame, and a compaction component, a hammer suspension mechanism, and a drive mechanism installed on the support frame; The compaction assembly is positioned directly above the sample; The hammer suspension mechanism is used to control the compaction component to move closer to or away from the sample; The driving mechanism is used to drive the compaction component to perform high-frequency compaction of the sample, so that the sample reaches a dense state under the set pressure and vibration conditions. It also includes drilling equipment; The drilling device includes a drilling mechanism, a drill string, a drill rod, and a jacking mechanism; The drilling mechanism is used to control the rotation of the drill rod and drill string; The drill rod and drill bit are positioned directly above the sample; The jacking mechanism is used to force the drill bit to approach or move away from the sample, thereby drilling the dense sample. It also includes a pressure sensor, which is located at the bottom of the support frame and is used to monitor the downward pressure of the sample bucket on the pressure sensor, thereby inferring the resistance of the sample bucket to the drill bit. It also includes a dynamic torque and speed sensor, which is disposed between the drilling mechanism and the drill rod to monitor the drill rod speed and torque; It also includes a second tension and compression sensor, which is set between the dynamic torque and speed sensor and the drill pipe to monitor the resultant force of the weight of the drill pipe and drill string and the drilling resistance, and thereby infer the drilling resistance. It also includes a wire-type displacement gauge mounted on a support frame, wherein the end of the monitoring line of the wire-type displacement gauge is connected to the platform and is used to monitor the displacement values ​​of the platform and the drilling tool.

2. The sand and gravel formation drilling model test platform for drill bit selection according to claim 1, characterized in that, It also includes a limiting mechanism, which on the one hand guides the tamping component during the lifting process to prevent the tamping component from tilting, and on the other hand transfers the tamping energy to the sample to prevent air vibration. The limiting mechanism includes: a limiting block, a slider, and a connecting rod; The limiting block has a slot inside; The slider is slidably disposed within the slot of the limiting block; The connecting rod is vertically arranged, with its bottom end connected to the drive mechanism and its top end extending through the through hole inside the limiting block to the slot and connecting to the slider. The connecting rod moves longitudinally within the limiting block through the sliding connection between the slider and the slot.

3. The sand and gravel formation drilling model test platform for drill bit selection according to claim 1, characterized in that, The compaction assembly includes a tamping plate and a tamping hammer; The tamping plate is positioned above the sample to ensure close contact with the loose sample. The tamping hammer is positioned on the upper side of the tamping plate to control the close contact between the tamping plate and the sample, thereby enabling the sample to achieve a higher degree of compaction.

4. The sand and gravel formation drilling model test platform for drill bit selection according to claim 1, characterized in that, It also includes a counterweight block set on the surface of the sample to pressurize the sample so that the sample can reach the same stress state as the prototype drill bit. The counterweight also has a through hole in the middle to ensure that the drill can move downwards into the sample to complete the drilling work.

5. The sand and gravel formation drilling model test platform for drill bit selection according to claim 1, characterized in that, It also includes a rotating conductive slip ring, which is located at the bottom of the second fixed frame and is a 360° rotating conductive device to prevent the data transmission line of the second tension and compression sensor from getting tangled on the drill rod.

6. The method of using the sand and gravel formation drilling model test platform for drill bit selection as described in any one of claims 1-5, characterized in that, Includes the following steps: Step S1: Measure the particle size distribution of the prototype drilling formation. The particle size model of the prototype drilling formation is a multiple of the set geometric similarity constant of the particle size used in the test. After preparing the corresponding particle aggregate sample required for the model test, divide the particle aggregate sample into three parts and measure and record the mass of the empty sample bucket. Step S2: Slowly fill any sample into the sample container; smooth the sample surface, and then tap the sample container wall several times to make the sample sink. Step S3: Place the sample container directly below the ramming plate and fix it in place; Step S4: Start the jacking mechanism to move the vibratory motor, steel rammer, and rammer plate downwards, so that the rammer plate is in close contact with the sample. Close the jacking mechanism, vibrate for 6 minutes, and then start the jacking mechanism again to lift the vibratory motor. Step S5: Repeat steps S2-S4 to vibrate and compact the second and third layers of the sample. Step S6: Place the straight steel bar at the diameter position of the sample barrel, measure the height of the sample after vibration, record and calculate the sample height; Step S7: Measure and record the mass of the sample container and the sample. Subtract the mass of the sample container to get the mass of the sample. Calculate the density of the dense sample. It also includes a method that uses two consecutive drilling operations to calculate the difference between the resistance torque and the resistance, specifically including the following steps: Step S10: Perform the first drilling of the compacted sample. The drilling mechanism controls the rotation of the drill rod and drill string, while the jacking mechanism controls its downward movement, continuously drilling into the compacted sample until the bottom is reached. Then, the drill string is pulled up to the top of the sample. During this process, the resistance at different drilling heights is recorded. and resistive torque The value; Step S20: Conduct a second drilling test and record the resistance at different drilling heights. and resistive torque numerical value Step S30: During the second drilling process, the drilled soil is a loose sample produced from the soil from the first drilling. The drill string also bears the pressure and resistance of the loose soil column above it. Formula ⑤ is used to calculate the difference between the drill string's torque and resistance during the first drilling at the same depth and the drill string's torque and resistance during the second drilling. In the formula: This represents the difference in resistance between the two drilling operations; This represents the difference in resistance torque between the two drilling processes; This represents the resistance value during the first drilling attempt, expressed in N (N). This represents the drilling resistance value during the second drilling attempt, expressed in N (N). The torque of the drill string during the first drilling operation is represented by N·m and is monitored by a dynamic torque-speed sensor. The torque representing the resistance torque of the drill string during the second drilling operation is expressed in N·m and is monitored by a dynamic torque-speed sensor. Step S40: Since the resistance and torque caused by the overlying loose soil column are the same at the same location during the two drilling operations, the difference is calculated to offset the influence of the overlying loose soil column on the drilling resistance and torque of the model test. This avoids the problem of inaccurate calculations caused by the inconsistency between the dry drilling and non-soil removal drilling methods of the model test and the mud circulation and soil removal drilling methods of the prototype drilling tool. The difference is the additional resistance and torque required to drill a dense sample relative to drilling a loose sample. This difference is consistent with the resistance and torque experienced by the drilling tool during mud circulation and soil removal drilling of the prototype drilling tool, and is used to compare the differences in resistance and torque required by different drilling tools to drill dense samples.

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