Static cone penetration test apparatus and method for simultaneous sampling and determination of soft clay sensitivity

Abstract

This invention discloses a static cone penetration test apparatus for simultaneously sampling and determining the sensitivity of soft clay. It mainly includes a static cone penetration probe, a probe rod with a locking mechanism, a sampler, and a vane test device housed inside a large-diameter short probe rod. When the static cone penetration reaches a certain depth, the probe rod with the locking mechanism moves upwards along with the upper probe rod, while the sampler remains stationary under the friction of the surrounding soil. A spring lock secures the two components. When the upper probe rod penetrates downwards again, the sampler is simultaneously pressed into the soil to complete the undisturbed soil sampling. The retractable vane probe rod in the large-diameter short probe rod extends the vane head horizontally to measure the peak value and residual undrained shear strength of the soft clay, thereby determining the sensitivity. This invention utilizes the penetration device of a static cone penetration test, eliminating the need for a drilling rig, penetration device, and mud wall support, to obtain undisturbed soil samples and determine the undrained shear strength and sensitivity of soft clay at a certain depth.

Description

Technical Field

[0001] This invention belongs to the field of borehole sampling and in-situ testing in geotechnical engineering, and specifically relates to a test apparatus and method capable of borehole sampling, determining the sensitivity of soft clay, and conducting static cone penetration tests. Background Technology

[0002] Before designing and constructing various engineering projects, it is essential to determine the physical and mechanical properties of the foundation soil through laboratory or in-situ tests. Compared to laboratory tests, in-situ testing offers advantages such as reflecting the characteristics of soil and rock under natural stress, measuring a wider range of soil samples, and having a shorter testing cycle. The static cone penetration test (CPPT) utilizes quasi-static force to press a conical probe into the soil through a series of probes at a constant penetration rate. Based on the measured cone tip resistance, sidewall friction, and pore water pressure, soil layers can be divided, soil types can be classified, and soil physical and mechanical properties such as overconsolidation ratio, undrained shear strength, sand density, compression modulus, and consolidation coefficient can be estimated. Due to its advantages of continuous testing, abundant test data, high efficiency, speed, and economy, the static cone penetration test is currently the most widely used in-situ testing method in geotechnical engineering. However, the static cone penetration test cannot drill soil samples and cannot directly determine the undrained shear strength and sensitivity of soft clay.

[0003] When directly determining the physical and mechanical properties of soil through laboratory tests, undisturbed soil samples must first be collected on-site. Therefore, undisturbed soil sampling is a fundamental task in geotechnical engineering investigation. Currently, thin-walled samplers are commonly used for borehole sampling. Drilling equipment is used to rapidly and continuously penetrate the sampler into the soil using static pressure. Therefore, borehole sampling typically requires specialized drilling rigs and penetration devices, as well as the use of mud slurry for wall protection. Thus, it is necessary to combine a static cone penetration test (PCT) with a sampler. The PCT penetration device is used to penetrate the sampler to a certain depth in the soil, allowing for undisturbed soil sampling simultaneously with the static cone penetration test.

[0004] The sensitivity of soft clay refers to the ratio of the undisturbed shear strength of the original soil to that of its corresponding remolded soil. It can be used to evaluate the structural strength of clay and can be determined through the vane shear test. The vane shear test involves applying torque to the vane head inserted into the foundation soil, causing the vane head to twist at a constant speed in the soil to form a cylindrical failure surface. By measuring the resistance torque at failure and the final resistance torque, the peak and residual undisturbed shear strength of the soil can be obtained, and thus the sensitivity of soft clay can be calculated. However, conducting the vane shear test also requires drilling (pre-drilled or self-drilled). Therefore, it is necessary to combine a static cone penetration test (CPPT) with a vane shear tester. Using the penetration device of the CPPT, the vane shear tester is inserted into the soil to a certain depth, allowing the sensitivity of soft clay to be determined simultaneously with the CPPT test. Summary of the Invention

[0005] To address the aforementioned limitations of existing technologies, this invention provides a static cone penetration test (CPPT) apparatus and method capable of simultaneously sampling and determining the sensitivity of soft clay. The invention incorporates a sampler attached to the outside of the CPPT probe and a vane shear tester housed inside the probe, allowing for simultaneous undisturbed soil sampling and soft clay sensitivity determination during the CPPT test. Using this apparatus, the undisturbed soil sample at a specified depth can be obtained without the need for a drilling rig, penetration device, or mud wall support. Drilling using the CPPT eliminates the need for pre-drilling or self-drilling, enabling the determination of the undrained shear strength and sensitivity of soil at a certain depth. Therefore, this invention combines CPPT, drilling sampling, and vane shear testing, significantly improving the efficiency and reducing the cost of geotechnical engineering investigations, thus possessing significant practical engineering value.

[0006] To address the aforementioned technical problems, this invention proposes a static cone penetration test apparatus for simultaneously sampling and measuring the sensitivity of soft clay. The apparatus includes a probe rod and a sampler. The probe rod comprises a static cone penetration probe rod, a large-diameter short probe rod, a middle long probe rod, and a static cone penetration probe head, all coaxially connected from top to bottom. The outer diameter of the large-diameter short probe rod is the same as the outer diameter of the sampler, and the outer diameter of the sampler is larger than the diameter of the static cone penetration probe head.

[0007] The large-diameter short probe is provided with a radial groove for installing a vane shearing instrument. The radial groove contains a telescopic vane shearing instrument probe. The head of the telescopic vane shearing instrument is provided with a vane head. The opening of the radial groove is provided with a vane shearing instrument side cover. The upper end of the opening is provided with a shallow groove for the side cover.

[0008] The middle probe rod includes a rod body and a probe buckle disposed at the lower end of the rod body. The probe buckle is a cylindrical structure that is connected to and coaxial with the bottom outer periphery of the rod body. The inner edge of the top of the cylinder is provided with a buckle bevel, and the middle part of the cylinder is provided with a spring locking hole.

[0009] The sampler includes a cylindrical body and a sampler buckle located at the top inner opening, which engages with the probe buckle. The cylindrical body has ventilation holes. The axial dimension of the inner wall of the sampler buckle is the same as the cylindrical depth of the probe buckle. The inner wall thickness of the sampler buckle is the same as the pre-reserved gap between the cylinder and the rod body of the probe buckle. The outer wall of the sampler buckle has a pair of spring lock mounting slots. The cylindrical body of the sampler has an annular groove corresponding to the axial position of the spring lock mounting slots. The annular groove contains a spring lock mounting hole aligned with the spring lock mounting slot. After the spring lock mounting slot and spring lock mounting hole are aligned, a spring lock is installed within them. A detachable ring is located within the annular groove. The inner surface of the detachable ring has a boss aligned with the spring lock mounting slot. After the detachable ring is installed, the boss abuts against the spring lock.

[0010] The probe rod is provided with a cable channel that runs through the static cone penetration probe rod, the large-diameter short probe rod, and the middle long probe rod. The cable and data line of the static cone penetration probe are led out from the cable channel. The rear wall of the radial groove is provided with a through hole that runs through the cable channel. The cable and data line of the telescopic vane probe rod of the vane shearing instrument are led out from the cable channel after passing through the through hole in the rear wall of the radial groove.

[0011] Furthermore, in the static cone penetration test apparatus for simultaneously sampling and measuring the sensitivity of soft clay described in this invention, wherein:

[0012] The spring lock includes a lock head, a spring is provided on the inner side of the lock head, and a spring lock inclined surface is provided on the lower end face of the lock head, which matches the snap-fit ​​inclined surface of the probe buckle.

[0013] The upper and lower ends of the large-diameter short probe are welded to the static cone penetration probe and the middle long probe, respectively, and the connection between the static cone penetration probe and the middle long probe is a threaded connection.

[0014] The bottom surface of the large-diameter short probe is the sampler bearing surface, the top surface of the sampler is the sampler receiving surface, and the inner wall of the sampler cylinder and the outer wall of the middle long probe are in clearance fit; when assembling the sampler, the sampler receiving surface is pressed against the sampler bearing surface.

[0015] The detachable ring consists of two interlocking semicircular rings, referred to as semicircular ring A and semicircular ring B respectively. A screw is pre-installed on the open end face of semicircular ring A, and a threaded hole coaxial with the screw is provided on the open end face of semicircular ring B. When installing the detachable ring, align the protrusions on the inner surfaces of semicircular ring A and semicircular ring B with the spring lock, and then screw the screw into the opposite threaded hole.

[0016] The tests conducted using the static cone penetration test apparatus for simultaneously sampling and measuring the sensitivity of soft clay proposed in this invention include:

[0017] 1) Static cone penetration test: The probe is driven into the soil at a speed of 2 cm / s using a penetration device, and the cone tip resistance, side wall friction and pore water pressure of the soil at different depths are measured;

[0018] 2) Vane shear test: Move the probe upwards, open the side cover of the vane shear tester, extend the telescopic vane probe, and extend the vane head a certain distance horizontally; rotate the probe clockwise to generate torque at the vane head until the torque data collection system shows a peak torque, measure the peak torque, and calculate the peak undrained shear strength; continue to rotate the probe clockwise 6 times, measure the final torque, and calculate the residual undrained shear strength; the ratio of the peak torque to the residual undrained shear strength is the sensitivity of soft clay; after completing the test, shorten the telescopic vane probe, retract the vane head into the large-diameter short probe, and close the side cover of the vane shear tester;

[0019] 3) Drilling and Sampling: After the probe reaches the sampling depth, stop drilling and pull the probe upward. At this time, the sampler remains stationary due to the friction of the surrounding soil. When the probe's locking clip moves upward to the sampler's locking clip position, the probe and sampler are locked together. The probe is then driven downward again, carrying the sampler downward into the soil, and the soil sample gradually enters the sampler. After the soil has completely entered the sampler, the probe is moved upward and pulled upward together with the sampler. Under the action of the friction between the soil sample and the inner wall of the sampler and the negative pressure inside the sampler, the soil sample moves upward with the sampler, thus completing the sampling of undisturbed soil.

[0020] Furthermore, in the static penetration test, the large-diameter short probe rod serves to enlarge the hole and reduce the penetration force.

[0021] During the drilling sampling, the vent on the sampler allows the gas in the sampler to flow out, thus avoiding the generation of high gas pressure in the sampler.

[0022] The project combination for completing the experiment can be one of the following:

[0023] Only static cone penetration tests were conducted.

[0024] Perform static cone penetration tests and vane shear tests;

[0025] Conduct static cone penetration tests and borehole sampling;

[0026] Static cone penetration tests, vane shear tests, and borehole sampling were conducted.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] (1) Although static cone penetration tests can measure multiple data such as cone tip resistance, sidewall friction and pore water pressure, and then indirectly estimate the physical and mechanical parameters of the soil through empirical formulas, they cannot be used for borehole sampling. The device of this invention can obtain undisturbed soil samples during static cone penetration tests, which can be used for indoor tests to directly determine the physical and mechanical parameters of the soil.

[0029] (2) Although the static cone penetration test can indirectly estimate the undrained shear strength of the soil through the cone tip resistance, it cannot directly determine the undrained shear strength of the soil. The device of the present invention can perform vane shear test during the static cone penetration test, and directly determine the undrained shear strength of soft clay.

[0030] (3) Currently, drilling sampling usually requires a special drilling rig and penetration device, as well as mud wall protection. This invention proposes a sampler that can be attached to the outside of the static cone penetration test probe. The sampler is penetrated to a specified depth using the penetration device of the static cone penetration test. No drilling rig, penetration device and mud wall protection are required to obtain undisturbed soil samples at a specified depth.

[0031] (4) Currently, when conducting vane shear tests, it is necessary to first perform pre-drilling or self-drilling. This invention proposes a vane shear instrument that can be installed inside the static cone penetration test rod. By using static cone penetration test for drilling, it is not necessary to perform pre-drilling or self-drilling. The vane shear test can be performed at a specified depth to determine the undrained shear strength and sensitivity of soft clay.

[0032] (5) This invention innovatively combines a static cone penetrometer, a sampler, and a vane shear apparatus, which can obtain undisturbed soil samples during the static cone penetrometer test and directly determine the undrained shear strength and sensitivity of soft clay in situ. This can greatly improve the efficiency of geotechnical engineering investigation and reduce the cost of geotechnical engineering investigation. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the overall structure of the experimental device of the present invention;

[0034] Figure 2 yes Figure 1 A schematic diagram of the probe and probe rod shown in the figure;

[0035] Figure 3 yes Figure 1 A schematic diagram of the sampler shown;

[0036] Figure 4 yes Figure 1 A cross-sectional view of the large-diameter short probe shown;

[0037] Figure 5 yes Figure 4 The side view of the large-diameter short probe shown;

[0038] Figure 6 yes Figure 4 A cross-sectional view of the large-diameter short probe with the crosshead protruding.

[0039] Figure 7 yes Figure 6 The side view of the large-diameter short probe shown;

[0040] Figure 8 This is a front sectional view of the test device of the present invention in the unlocked state of the spring lock;

[0041] Figure 9 This is a front sectional view of the spring lock in the locked state of the test device of the present invention;

[0042] Figure 10 yes Figure 9 The top sectional view of the spring lock in the locked state;

[0043] Figure 11 yes Figure 10 A top sectional view of the semicircular ring A in the fixed ring shown;

[0044] Figure 12 yes Figure 11 Left view of the semicircular ring A shown;

[0045] Figure 13 yes Figure 10 A top sectional view of the semicircular ring B in the fixed ring shown;

[0046] Figure 14 yes Figure 13 The right view of the semicircular ring B shown;

[0047] Figure 15 This is the process of conducting an experiment using the experimental device of the present invention, wherein: (a) the experimental device is in the state of penetrating the soil, (b) the retaining cover 22 is in the state of being open, (c) the crosshead 7 is in the state of being extended, (d) the crosshead is in the state of being retracted, (e) the probe is pulled upwards, (f) the sampling tube and the probe are locked together, (g) the sampling tube is pressed into the soil, and (h) the soil enters the sampling tube.

[0048] In the picture:

[0049] 1-Large diameter short probe rod; 2-Middle length long probe rod; 3-Sampler; 4-Static cone penetration test probe.

[0050] 5-Cable channel; 6-Retractable cross-plate probe; 61-Through hole; 7-Cross-plate head

[0051] 71-Radial groove; 72-Side cover shallow groove; 8-Sampler bearing surface; 9-Probe buckle.

[0052] 10-Snap-on bevel; 11-Spring lock hole; 12-Reserved gap; 13-Sampling device force-bearing surface

[0053] 14-Spring lock 15-Sampler buckle 16-Spring lock bevel 17-Sampler buckle inner wall

[0054] 18-Lock head 19-Spring 20-Ventilation hole 21-Static cone penetration probe

[0055] 22-Side cover of the cross-plate shearer; 23-Removable ring; 231-Semi-circular ring A

[0056] 232-Semicircular ring B233-Screw 234-Threaded hole 235-Boss Detailed Implementation

[0057] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the following embodiments are by no means intended to limit the present invention.

[0058] like Figure 1 The present invention proposes a static cone penetration test device for simultaneously sampling and measuring the sensitivity of soft clay. The test device includes a probe rod and a sampler. The probe rod includes a static cone penetration probe rod 21, a large-diameter short probe rod 1, a middle long probe rod 2, and a static cone penetration probe 4, which are coaxially connected from top to bottom.

[0059] The upper and lower ends of the large-diameter short probe 1 are connected to the static cone penetration probe 21 and the middle long probe 2 by welding, respectively. The static cone penetration probe 4 is connected to the middle long probe 2 by thread.

[0060] like Figures 4 to 7 As shown, the large-diameter short probe 1 is provided with a radial groove 71 for installing a vane shear. The radial groove 71 is provided with a telescopic vane probe 6 of the vane shear. The head of the telescopic vane probe 6 is provided with a vane head 7. The groove opening of the radial groove 71 is provided with a vane shear side cover 22. The upper end of the groove opening is provided with a shallow groove 72 for the side cover. The rear part of the radial groove 71 is provided with a through hole 61 for passing through the vane shear cable and data cable.

[0061] In this embodiment, the telescopic vane probe 6 is composed of multiple sleeves of different diameters. When extended, the vane head 7 can be extended a certain distance in the horizontal direction, thereby measuring the peak value and residual undrained shear strength of soft clay at a certain depth, and thus determining the sensitivity of soft clay at that depth.

[0062] like Figure 2As shown, the middle probe 2 includes a rod body with the same diameter as the static penetration probe 21. A probe buckle 9 is provided at the lower end of the rod body. The probe buckle 9 can be interlocked with the sampler buckle 15. The probe buckle 9 is a cylindrical structure that is connected to the bottom outer periphery of the rod body and is coaxial. A buckle inclined surface 10 is provided on the inner edge of the top of the cylinder. A spring locking hole 11 is provided in the middle of the cylinder.

[0063] like Figure 1 and Figure 3 As shown, the sampler 3 includes a cylindrical body 31 and a sampler buckle 15 located at the top inner opening, which cooperates with the probe buckle 9. The cylindrical body has a vent hole 20. The axial dimension of the inner wall 17 of the sampler buckle 15 is consistent with the cylindrical depth of the probe buckle 9. The thickness of the inner wall 17 of the sampler buckle is consistent with the reserved gap 12 between the cylinder and the rod of the probe buckle 9. The outer wall of the sampler buckle 15 has a pair of spring lock mounting slots. The cylindrical body of the sampler 3 has an annular groove corresponding to the axial position of the spring lock mounting slots. The annular groove has a spring lock mounting hole aligned with the position of the spring lock mounting slot. After the lock mounting slot and spring lock mounting hole are aligned, a spring lock 14 is installed. The spring lock 14 includes a lock head 18, with a spring 19 inside the lock head 18. The lower end face of the lock head 18 has a spring lock bevel 16. The spring lock bevel 16 is aligned with and matches the snap-fit ​​bevel 10 of the probe snap-fit ​​9. When the spring lock bevel 16 and the snap-fit ​​bevel 10 come into contact, they horizontally compress the spring lock 14, compressing the spring 19 and causing the lock head 18 to move inward. The probe snap-fit ​​9 gradually enters the sampler snap-fit ​​15. When the spring lock hole 11 is at the same height as the lock head 18, the lock head 18 enters the spring lock hole 11, and the probe snap-fit ​​9 and the sampler snap-fit ​​15 are locked together. Figure 8 The spring lock in the experimental apparatus of the present invention is shown in an unlocked state. Figure 9 and Figure 10 The spring lock is shown in the locked state of the test apparatus of the present invention.

[0064] A detachable ring 23 is provided within the annular groove. The inner surface of the detachable ring 23 has a boss 235 aligned with the spring lock mounting groove. After the detachable ring 23 is installed, the boss 235 abuts against the spring lock 14. Figure 10 , Figure 11 and Figure 13 As shown, the detachable ring 23 is composed of two interlocking semicircular rings, denoted as semicircular ring A231 and semicircular ring B232 respectively. A screw 233 is pre-installed on the open end face of semicircular ring A231, as shown... Figure 11 and Figure 12 As shown; the open end face of the semi-circular ring B232 is provided with a threaded hole 234 coaxial with the screw 233, as shown. Figure 13 and Figure 14 As shown; when installing the detachable ring 23, align the bosses 235 on the inner surfaces of the semicircular rings A231 and B232 with the spring lock 14, and then screw the screw 233 into the opposite threaded hole 234 to fix the connection. After sampling, unscrew the screw 233 to remove the detachable ring 23 from the sampler 3, and then unlock the probe clip 9 from the sampler clip 15.

[0065] like Figure 1 , Figure 2 and Figure 3 As shown, the outer diameter of the sampler 3 is the same as the outer diameter of the large-diameter short probe 1. The bottom surface of the large-diameter short probe 1 is the sampler bearing surface 8, and the top surface of the sampler 3 is the sampler receiving surface 13. The inner wall of the sampler 3 cylinder and the outer wall of the middle long probe 2 are in clearance fit. When assembling the sampler 3, the sampler receiving surface 13 is pressed against the sampler bearing surface 8.

[0066] like Figure 1 and Figure 2 As shown, the probe rod is provided with a cable channel 5 that runs through the static cone penetration probe rod 21, the large-diameter short probe rod 1 and the middle long probe rod 2, and the cable of the static cone penetration probe 4 is led out from the cable channel 5.

[0067] During the static penetration test, the sampler 3 is attached to the outside of the middle long probe 2 with a buckle. The sampler force-bearing surface 13 is in contact with the sampler bearing surface 8 at the bottom of the large-diameter short probe 1. When the large-diameter short probe 1 penetrates downward, the sampler 3 follows the large-diameter short probe 1 and penetrates downward together. At the intended sampling depth, the large-diameter short probe 1 and the middle long probe 2 with a clip are pulled upwards. The sampler 3 remains stationary under the friction of the surrounding soil. When the probe clip 9 of the middle long probe 2 with a clip moves upwards to the position of the sampler clip 15, the probe clip 9 can interlock with the sampler clip 15. When the static penetration test is carried out downwards again, the sampler 3 moves downwards together with the middle long probe 2 with a clip, and the soil can gradually enter the sampler 3. After the soil sample has completely entered, the middle long probe 2 with a clip and the sampler 3 with the existing soil sample are pulled upwards out of the ground, thus completing the sampling of the undisturbed soil.

[0068] In this embodiment, the number of vent holes 20 provided on the sampler 3 cylinder is four evenly distributed along the same circumference. Specifically, four vent holes 20 are provided on the sampler 3 30cm below the sampler buckle 15. The vent holes 20 are constructed of a funnel-shaped membrane made of rubber. When the internal air pressure is high, it will expand and open, allowing gas to flow out, thereby avoiding the generation of high air pressure in the sampler 3 during sampling and preventing soil samples from entering the sampler 3. When the external air pressure is high, it will contract and close the opening, preventing external soil samples and air from entering the sampling cylinder. This creates a negative pressure in the sampling cylinder when the probe is pulled upward, which helps the soil sample move upward with the sampler 3.

[0069] In this invention, the retractable vane probe 6 and the vane head 7 are disposed in a radial groove 71 of the large-diameter short probe 1. During static penetration, the large-diameter short probe 1 penetrates downwards along with the static penetration probe 21. When the depth for determining the sensitivity of soft clay is reached, penetration is stopped, and the side cover 22 of the vane shearing instrument is pulled upwards along the shallow groove 72 of the side cover, thereby opening the side cover 22 of the vane shearing instrument, extending the retractable vane probe 6, and causing the vane head 7 at its end to extend out of the large-diameter short probe 1. Figure 6 As shown. Then, rotate the probe rod clockwise to generate torque at the vane head 7. The peak undrained shear strength can be calculated from the peak torque. Then, continue rotating clockwise for 6 more revolutions and measure the torque again to calculate the residual undrained shear strength. The ratio of the peak to the residual undrained shear strength is the sensitivity of soft clay. After the measurement is completed, shorten the telescopic vane probe rod 6, thereby driving the vane head 7 back into the large-diameter short probe rod 1. Close the side cover 22 of the vane shear apparatus, as shown. Figure 4 As shown.

[0070] This invention provides a flexible static cone penetration test (CPPT) for simultaneously sampling and determining the sensitivity of soft clay. It combines CPPT with borehole sampling and vane shear testing. Utilizing the penetration device of the CPPT, it eliminates the need for drilling rigs, penetration devices, and mud wall support to obtain undisturbed soil samples at a specific depth. Furthermore, it eliminates the need for pre-drilling or self-drilling to determine the undrained shear strength and sensitivity of soft clay at a designated depth. Therefore, this invention significantly improves the efficiency of engineering surveys and reduces their costs. The testing device of this invention can perform the following tests: 1) CPPT only; 2) simultaneous CPPT and vane shear testing; 3) simultaneous CPPT and borehole sampling; 4) simultaneous CPPT, vane shear testing, and borehole sampling. The steps for each test are as follows:

[0071] 1) Perform only static cone penetration tests, following these steps:

[0072] 1-1) The static cone penetration probe 4 is fixedly connected to the middle long probe rod 2 with a buckle by thread, and the large diameter short probe rod 1 is welded to the middle long probe rod 2; the static cone penetration probe rod 21 is welded to the large diameter short probe rod 1, and the sampler 3 is installed on the outside of the middle long probe rod 2.

[0073] 1-2) The static cone penetration test rod 21 is driven into the soil at a speed of 2 cm / s using a penetration tester, and the cone tip resistance, side wall friction and pore water pressure of the soil at different depths are measured.

[0074] 1-3) After the test is completed, pull out the static cone penetration test rod 21, the large-diameter short probe rod 1, the medium-length probe rod 2 and the static cone penetration test probe 4 together to end the entire test;

[0075] Although the above steps are basically the same as those of traditional static cone penetration tests, the outer diameter of the large-diameter short probe 1 in the test device of this invention is larger than that of the static cone penetration probe 21, which can play the role of enlarging the hole and help reduce the friction between the soil and the upper static cone penetration probe 21, thereby greatly reducing the penetration force.

[0076] 2) Simultaneously conduct static cone penetration tests and vane shear tests, following these steps:

[0077] 2-1) Perform a static cone penetration test as described in steps 1-1) and 1-2) above;

[0078] 2-2) The static cone penetration test rod 21 is driven into the soil at a speed of 2 cm / s using a penetration device. After reaching the specified depth, the penetration is stopped and a vane shear test is performed.

[0079] 2-3) Move the side cover 22 of the vane shear apparatus upwards to open it, extend the telescopic vane probe 6, and extend the vane head 7 a certain distance horizontally; rotate the probe clockwise to generate torque in the vane head 7 until the data collection system displays a peak torque, measure the peak torque, and calculate the peak undrained shear strength; continue rotating clockwise for 6 turns to determine the final torque and calculate the residual undrained shear strength. The ratio of the peak torque to the residual undrained shear strength is the sensitivity of the soft clay.

[0080] 2-4) After completing the depth measurement, shorten the telescopic vane probe rod 6, retract the vane head 7 into the large-diameter short probe rod 1, and close the side cover 22 of the vane shearing instrument.

[0081] 2-5) Repeat steps 2-2) to 2-4) above to obtain the static cone penetration test results, undrained shear strength and sensitivity of soil at different depths.

[0082] 2-6) After the test is completed, pull out the static cone penetration test rod 21, the large-diameter short probe rod 1, the probe rod with clip 2 and the static cone penetration test probe 4 together to end the entire test.

[0083] 3) Simultaneously conduct static cone penetration tests and borehole sampling, following these steps:

[0084] 3-1) Perform a static cone penetration test as described in steps 1-1) and 1-2) above;

[0085] 3-2) The static cone penetration test rod 21 is driven into the soil at a speed of 2 cm / s using a penetration tester. After reaching the specified depth, the penetration is stopped and borehole sampling is carried out.

[0086] 3-3) Pull the large-diameter short probe 1 and the probe 2 with the clip upwards. At this time, the sampler 3 remains stationary under the action of the friction of the surrounding soil.

[0087] 3-4) When the spring lock ramp 16 contacts the probe buckle ramp 10, the probe buckle 9 will horizontally push the lock head 18 and compress the spring 19. The probe buckle 9 will gradually enter the sampler buckle 15. When the probe buckle 9 is fully entered into the sampler buckle 15, the height of the spring lock hole 11 and the lock head 18 is exactly the same. The lock head 18 enters the spring lock hole 11, and the reserved gap 12 is completely fitted with the inner wall 17 of the sampler buckle. The probe buckle 9 and the gap in the sampler buckle 15 are completely fitted. At this time, the probe buckle 9 and the sampler buckle 15 are locked.

[0088] 3-5) Insert the probe 2 with the clip downwards again. At this time, the sampler 3 will also penetrate downwards into the soil, and the soil sample will gradually enter the sampler 3. When the soil sample enters the sampler 3, it will cause the sealed space inside the sampler 3 to decrease and the air pressure to increase. The vent 20 is constructed of a funnel-shaped membrane made of rubber. When the internal air pressure is high, it will expand and open, allowing gas to flow out. This inevitably leads to a high air pressure in the sampler, making it difficult for the soil sample to enter the sampler 3.

[0089] 3-6) After the soil has completely entered the sampler 3, pull the static cone penetration test rod 21, the large-diameter short probe rod 1, the probe rod with clip 2, and the sampler 3 together upwards.

[0090] 3-7) When the sampler 3 moves upward, the soil sample tends to move downward, which will increase the sealed space inside the sampler. The vent 20 is constructed of a funnel-shaped membrane made of rubber. When the external air pressure is high, it will contract to close the opening, preventing external soil sample and air from entering the sampling tube, thereby creating negative pressure inside the sampler 3.

[0091] 3-8) Under the action of friction and negative pressure between the soil sample and the inner wall of the sampler, the soil sample moves upward along with the sampler 3, thus completing the sampling of undisturbed soil. The total length of the sampler is about 1.3 m, and the length of the static cone penetrometer is about 0.3 m, so an undisturbed soil sample of about 1 m in length can be obtained.

[0092] 3-9) After sampling is completed, unscrew screw 24 and remove detachable ring 23 from sampler 3, so that probe clip 9 and sampler clip 15 can be unlocked.

[0093] 3-10) Repeat steps 3-1) to 3-9 above to obtain the static cone penetration test results of soil at different depths and obtain undisturbed soil samples of soil at different depths.

[0094] 4) Simultaneously conduct static cone penetration tests, vane shear tests, and borehole sampling, such as... Figure 15 As shown, the steps are as follows:

[0095] 4-1) Perform a static cone penetration test as described in steps 1-1) and 1-2) above;

[0096] 4-2) The static cone penetration test probe 21 is driven into the soil at a speed of 2 cm / s using a penetration tester. After reaching the specified depth, the penetration is stopped. Then, following the steps 2-2) to 2-5) above, the peak value and residual undrained shear strength of the soil at that depth are measured, and the sensitivity of the soil at that depth is calculated.

[0097] 4-3) Continue to penetrate downwards for static cone penetration tests. After reaching the next depth, conduct vane shear tests again to determine the sensitivity of the soft clay at that depth.

[0098] 4-4) After reaching the sampling depth, stop the penetration and pull out the large-diameter short probe 1 and the probe 2 with the buckle upward. At this time, the sampler 3 remains stationary under the action of the friction of the surrounding soil.

[0099] 4-5) When the probe clip 9 with the clip 2 moves upward to the position of the sampler clip 15, the probe clip 9 and the sampler clip 15 are locked together.

[0100] 4-6) Insert the snap-fit ​​probe 2 downwards again, and the sampler 3 will follow and penetrate the soil. The soil sample will gradually enter the sampler 3. The vent 20 allows gas to flow out, thus avoiding the generation of high air pressure in the sampler 3.

[0101] 4-7) After the soil has completely entered the sampler 3, pull the static cone penetration test rod 21, the large-diameter short probe rod 1, the probe rod with clip 2, and the sampler 3 together upwards.

[0102] 4-8) Under the action of friction between the soil sample and the inner wall of the sampler and the negative pressure inside the sampler, the soil sample moves upward along with the sampler 3, thus completing the sampling of the undisturbed soil.

[0103] 4-9) Repeat steps 4-1) to 4-8) above to obtain the static cone penetration test results, sensitivity and undisturbed soil samples of soil at different depths.

[0104] Although the present invention has been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many improvements and modifications under the guidance of the present invention without departing from the spirit of the present invention, such as changing the structure of the locking device between the sampler and the probe, changing the arrangement position and method of the vane shearing instrument, etc., all of which are within the protection scope of the present invention.

Claims

1. A static cone penetration test apparatus for simultaneously sampling and determining the sensitivity of soft clay, the apparatus comprising a probe and a sampler, characterized in that, The probe includes a static cone penetration probe (21), a large-diameter short probe (1), a middle long probe (2), and a static cone penetration probe (4) connected coaxially from top to bottom; the outer diameter of the large-diameter short probe (1) is the same as the outer diameter of the sampler (3), and the outer diameter of the sampler (3) is larger than the diameter of the static cone penetration probe (4); The large-diameter short probe (1) is provided with a radial groove for installing a vane shearing instrument. The radial groove (71) is provided with a telescopic vane probe (6) of the vane shearing instrument. The head of the telescopic vane probe (6) is provided with a vane head (7). The groove opening of the radial groove (71) is provided with a vane shearing instrument side cover (22). The upper end of the groove opening is provided with a side cover shallow groove (72). The middle probe (2) includes a rod body and a probe buckle (9) provided at the lower end of the rod body. The probe buckle (9) is a cylindrical structure that is connected to the bottom outer periphery of the rod body and is coaxial. The inner edge of the top of the cylindrical structure is provided with a buckle slope (10), and the middle part of the cylinder is provided with a spring locking hole (11). The sampler (3) includes a cylindrical body and a sampler buckle (15) located at the top inner opening, which cooperates with the probe buckle (9). The cylindrical body has a vent hole (20). The axial dimension of the inner wall (17) of the sampler buckle (15) is consistent with the cylindrical depth of the probe buckle (9). The thickness of the inner wall (17) of the sampler buckle is consistent with the reserved gap (12) between the cylinder and the probe body of the probe buckle (9). The outer wall of the sampler buckle (15) has a pair of spring lock mounting slots. 3) The cylinder body is provided with an annular groove corresponding to the axial position of the spring lock mounting groove. The annular groove is provided with a spring lock mounting hole aligned with the position of the spring lock mounting groove. After the spring lock mounting groove and the spring lock mounting hole are aligned, a spring lock (14) is installed in it. The annular groove is provided with a detachable ring (23). The inner surface of the detachable ring (23) is provided with a boss (235) aligned with the position of the spring lock mounting groove. After the detachable ring (23) is installed, the boss (235) abuts against the spring lock (14). The probe rod is provided with a cable channel that runs through the static cone penetration probe rod (21), the large-diameter short probe rod (1), and the middle long probe rod (2). The cable and data line of the static cone penetration probe (4) are led out from the cable channel. The rear wall of the radial groove (71) is provided with a through hole (61) that runs through the cable channel (5). The cable and data line of the telescopic cross plate probe rod (6) of the cross plate shearing instrument are led out from the cable channel (5) after passing through the through hole (61) on the rear wall of the radial groove.

2. The static cone penetration test apparatus for simultaneously sampling and measuring the sensitivity of soft clay according to claim 1, characterized in that, The spring lock (14) includes a lock head (18), a spring (19) is provided on the inner side of the lock head (18), and a spring lock inclined surface (16) is provided on the lower end face of the lock head (18). The spring lock inclined surface (16) matches the snap-fit ​​inclined surface (10) of the probe buckle (9).

3. The static cone penetration test apparatus for simultaneously sampling and measuring the sensitivity of soft clay according to claim 1, characterized in that, The upper and lower ends of the large-diameter short probe (1) are connected to the static cone penetration probe (21) and the middle long probe (2) by welding, respectively. The connection between the static cone penetration probe (4) and the middle long probe (2) is a threaded connection.

4. The static cone penetration test apparatus for simultaneously sampling and measuring the sensitivity of soft clay according to claim 1, characterized in that, The bottom surface of the large-diameter short probe (1) is the sampler bearing surface (8), and the top surface of the sampler (3) is the sampler receiving surface (13). The inner wall of the sampler (3) and the outer wall of the middle long probe (2) are in clearance fit. When assembling the sampler (3), the sampler receiving surface (13) is pressed against the sampler bearing surface (8).

5. The static cone penetration test apparatus for simultaneously sampling and measuring the sensitivity of soft clay according to claim 1, characterized in that, The detachable ring (23) is composed of two interlocking semicircular rings, which are respectively referred to as semicircular ring A (231) and semicircular ring B (232). A screw (233) is pre-set on the open end face of semicircular ring A (231), and a threaded hole (234) coaxial with the screw (233) is provided on the open end face of semicircular ring B (232). When installing the detachable ring (23), align the boss (235) on the inner surface of semicircular ring A (231) and semicircular ring B (232) with the spring lock (14), and then screw the screw (233) into the threaded hole (234) opposite to it.

6. The static cone penetration test apparatus for simultaneously sampling and measuring the sensitivity of soft clay according to claim 1, characterized in that, The number of the vent holes (20) set on the cylinder of the sampler (3) is four evenly distributed along the same circumference, and the vent holes (20) are funnel-shaped membranes made of rubber.

7. A static cone penetration test method for simultaneously sampling and determining the sensitivity of soft clay, characterized in that, Using the test apparatus as described in any one of claims 1 to 6, the cable and data line are connected to the monitoring equipment, and wherein: 1) Static cone penetration test: The probe was driven into the soil at a speed of 2 cm / s using a penetration tester, and the cone tip resistance, sidewall friction and pore water pressure of the soil at different depths were measured. 2) Vane shear test: Move the probe upwards, open the side cover (22) of the vane shear apparatus, extend the telescopic vane probe (6), and extend the vane head (7) a certain distance in the horizontal direction; rotate the probe clockwise to generate torque in the vane head (7) until the torque data collection system shows a peak torque, measure the peak torque, and calculate the peak undrained shear strength; continue to rotate the probe clockwise 6 times, measure the final torque, and calculate the residual undrained shear strength; the ratio of the peak value to the residual undrained shear strength is the sensitivity of the soft clay; after completing the measurement, shorten the telescopic vane probe (6), retract the vane head (7) into the large-diameter short probe (1), and close the side cover (22) of the vane shear apparatus. 3) Drilling and sampling: After the probe reaches the sampling depth, it stops penetrating and is pulled out upwards. At this time, the sampler (3) remains stationary under the action of the friction of the surrounding soil. When the probe clip (9) moves upwards to the position of the sampler clip (15), the probe and the sampler are locked together. The probe is then penetrated downwards again, carrying the sampler (3) into the soil. The soil sample gradually enters the sampler (3). After the soil has completely entered the sampler (3), the probe is moved upwards and pulled out upwards along with the sampler (3). Under the action of the friction between the soil sample and the inner wall of the sampler and the negative pressure inside the sampler, the soil sample moves upwards along with the sampler (3), thus completing the sampling of the original soil.

8. The test method according to claim 7, characterized in that, In the static penetration test, the large-diameter short probe (1) serves to enlarge the hole and reduce the penetration force.

9. The test method according to claim 7, characterized in that, During the drilling sampling, the vent (20) on the sampler (3) allows the gas in the sampler (3) to flow out, thus avoiding the generation of high gas pressure in the sampler (3).

10. The test method according to claim 7, characterized in that, The project combination for completing the experiment can be one of the following: 1) Static cone penetration test; 1) Static cone penetration test and 2) vane shear test; 1) Static cone penetration test and 3) Borehole sampling; 1) Static cone penetration test, 2) vane shear test, and 3) borehole sampling.

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