A simulated in-situ soil sampling disturbance device and disturbance evaluation method

Abstract

The present invention relates to the field of rock and soil mechanics and engineering technology, and in particular to a simulated in-situ soil sampling disturbance device and a disturbance evaluation method. The hydraulic jacking sampling system of the device is placed in an axial compression system, and a through hole for a screw to pass through is provided at the center of the hydraulic jacking sampling system and the axial compression system, and a sample cap is provided at the bottom end of the screw, and the sample cap is located at the top of the soil sample; copper electrodes are provided at the top and bottom ends of the soil sample in the high-strength insulating plastic, respectively, and the copper electrodes at the top and bottom ends are connected to a resistivity acquisition module through a wire, and the copper electrode at the bottom end is connected to a pore pressure sensor through a wire; the hydraulic jacking sampling system and the axial compression system drive the screw to apply pressure to the soil sample in the high-strength insulating plastic, so that the pore pressure sensor and the resistivity acquisition module obtain corresponding data. The disturbance caused by sampling the soil under pressure at different depths is simulated, which is of great reference significance for obtaining soil parameters in indoor experiments.

Description

Technical Field

[0001] The invention relates to the field of rock and soil mechanics and engineering technology, and in particular to a simulated in-situ soil sampling disturbance device and a disturbance evaluation method. Background Art

[0002] In the field of geotechnical engineering, relevant scientific research and technical personnel mainly obtain the engineering property parameters of soil through drilling sampling and indoor tests. There are problems such as large sampling disturbance, discontinuous sampling points, and low reliability of test data. How to evaluate the disturbance occurring during the sampling process is an urgent problem to be solved. At present, some scholars use indoor tests to evaluate the disturbance of soil. Most of them use the physical and mechanical indicators of soil obtained by consolidation tests to evaluate the degree of disturbance of sampling. The mechanical indicators of soil used include porosity, pore water pressure, structural yield stress, shear strain, etc. These methods do not consider the influence of soil cutting by soil samplers.

[0003] The resistivity method reflects the properties of soil by testing the resistivity of the soil. It is widely used because of its advantages such as speed and low cost. The resistivity method has been widely used in testing the moisture content and strength of soil. In the process of soil sampling, the water and pore volume in the sample are changed due to the cutting of the soil sampler, and the resistivity will also change. How to use the resistivity method to evaluate the disturbance degree of the soil is a technical problem that has not been solved so far. Summary of the invention

[0004] In view of the above-mentioned shortcomings, the present invention provides a simulated in-situ soil sampling disturbance device and a disturbance evaluation method, and utilizes the resistivity method to study the disturbance degree of the soil after soil sampling.

[0005] The present invention adopts the following technical solution:

[0006] The simulated in-situ soil sampling disturbance device of the present invention comprises a high-strength insulating plastic for containing soil samples, the high-strength insulating plastic is arranged on a base, a drainage pipe connected to the high-strength insulating plastic is arranged in the base, a hydraulic jacking sampling system and an axial compression system are arranged above the high-strength insulating plastic; the hydraulic jacking sampling system is placed in the axial compression system, a through hole for a screw to pass through is arranged at the center of the hydraulic jacking sampling system and the axial compression system, a sample cap is arranged at the bottom end of the screw, and the sample cap is located on the top of the soil sample; copper electrodes are respectively arranged at the top and bottom ends of the soil sample in the high-strength insulating plastic, the copper electrodes at the top and bottom ends are connected to a resistivity acquisition module through a wire, and the copper electrode at the bottom end is connected to a pore pressure sensor through a wire;

[0007] The hydraulic jacking sampling system and the axial compression system drive the screw rod to apply pressure to the soil sample in the high-strength insulating plastic, so that the pore pressure sensor and the resistivity acquisition module obtain corresponding data.

[0008] The simulated in-situ soil sampling disturbance device of the present invention, the axial compression system includes porous insulating permeable stone, a steel frame, a lever frame, a weight, and a stand;

[0009] The steel frame is arranged on the platform, and the steel frame is composed of two parallel vertical rods, a horizontal rod on the top of the vertical rods, and a lever frame at the bottom of the vertical rods to form a frame structure, and the bottom end of the vertical rod passes through the platform and is connected to the lever frame;

[0010] A tray for placing weights is provided on the lever frame, and the deadweight of the weights is used to move the steel frame downward, and drive the screw to drive the sample cap to apply pressure to the sample;

[0011] The top and bottom of the soil sample of the high-strength insulating plastic are respectively arranged with porous insulating permeable stones.

[0012] The simulated in-situ soil sampling disturbance device of the present invention, the hydraulic jacking sampling system includes a sampler, a vertical rigid support, a screw rod, a hydraulic jack, a transmission, a coupling, a controller, a clamp, a load platform, and a round nut;

[0013] The vertical rigid support is arranged outside the high-strength insulating plastic container, and the height of the vertical rigid support is greater than the height of the high-strength insulating plastic container;

[0014] The center of the sampler is consistent with the center of the vertical rigid support, the screw extends into the sampler, the sample cap is placed in the sampler, and the bottom of the sampler is placed on the outside of the sample cap;

[0015] The hydraulic jack is connected to the coupling through a transmission, the coupling is connected to the screw rod, a controller is provided at the top of the screw rod, and the hydraulic jack, the coupling, the screw rod and the controller are vertically erected;

[0016] Circular nuts are respectively arranged at both ends of the load platform, and the circular nuts and the spiral rod form a threaded rotating part; the clamp is arranged on the load platform, and the clamp is used to clamp the sampler.

[0017] The simulated in-situ soil sampling disturbance device described in the present invention is characterized in that the outer side of the high-strength insulating plastic is constrained by a steel guard ring, and the inner side of the high-strength insulating plastic is in contact with the soil through a rubber film; the bottom end of the rubber film package is wrapped around the base, and the top end of the rubber film package is wrapped to the outer side of the bottom end of the sampler.

[0018] The simulated in-situ soil sampling disturbance device of the present invention has a clamp on the drainage pipe.

[0019] The evaluation method of the simulated in-situ soil sampling disturbance device of the present invention comprises the following steps:

[0020] (1) Cut the original soil sample, place the porous insulating permeable stone, copper electrode, soil sample, copper electrode, porous insulating permeable stone and sample cap on the base in sequence; connect the resistivity acquisition module and the pore pressure sensor, align the bolts with the sample cap; use rubber rings to tighten the two ends of the rubber membrane to the base and the sample cap respectively. Lay high-strength insulating plastic around the sample and tighten it with a steel guard ring, adjust the bolts to press the sample cap and compact the soil sample;

[0021] (2) Apply different numbers of weights to simulate the compressive state of the soil at different depths, and loosen the drainage clamp to drain the water in the compressed soil;

[0022] (3) Observe the pore pressure sensor until the pore pressure of the soil sample is dissipated to zero, clamp the drain pipe and stop draining. Start the resistivity acquisition device and record the resistivity ρ1 of the soil sample;

[0023] (4) Start the hydraulic jack and transmission, and push the sampler connected to the fixture into the soil sample until the soil sample is completely cut;

[0024] (5) With the bolts supporting the sample cap, slowly lift the sampler until the soil sample is completely separated from the sampler 3;

[0025] (6) Start the resistivity acquisition device and record the resistivity ρ2 of the soil sample after it is cut. The disturbance degree of soil sampling is obtained through the changes in the resistivity twice. The disturbance degree is expressed as:

[0026]

[0027] The evaluation method of the simulated in-situ soil sampling disturbance device described in the present invention obtains the disturbance degree D of the soil sampling. When the disturbance degree D is ≥ 10%, the soil sample is considered to be significantly disturbed; when the disturbance degree D is < 10%, it is considered to be slightly disturbed.

[0028] Beneficial Effects

[0029] The present invention proposes a simulated in-situ soil sampling disturbance device and disturbance evaluation method, designs axial compression, lateral insulation support, hydraulic jacking sampling, drainage control system and resistivity acquisition system, realizes automatic monitoring and acquisition of data, and simulates the disturbance caused by soil sampling under pressure at different depths, which is of great reference significance for obtaining soil parameters in indoor experiments. The entire system device has strong controllability, strong functionality, and is easy to carry, operate and promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the structure of the disturbance device for simulating in-situ soil sampling;

[0031] Figure 2This is a schematic diagram of the top view of the fixture and specimen of the in-situ soil sampling disturbance device;

[0032] Figure 3 Schematic diagram of the fixture and load platform structure for simulating in-situ soil sampling disturbance device;

[0033] The figure shows screw 1, steel frame 2, sampler 3, porous insulating permeable stone 4, rubber membrane 5, high-strength insulating plastic 6, steel guard ring 7, resistivity acquisition module 8, drain pipe 9, weight 10, clamp 11, base 12, copper electrode 13, hydraulic jack 14, sample 15, transmission 16, coupling 17, controller 18, sample cap 19, screw rod 20, vertical rigid bracket 21, round nut 22, clamp 23, load platform 24, guide ring 25, lever frame 26, pore pressure sensor 27, stand 28, and slide rail 29. DETAILED DESCRIPTION

[0034] In order to make the purpose and technical solution of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] like Figure 1 As shown, an embodiment of the simulated in-situ soil sampling disturbance device and disturbance evaluation method of the present invention introduces the resistivity method to evaluate the sampling disturbance size, designs axial compression, lateral insulation support, hydraulic jacking sampling, drainage control system and resistivity acquisition system, realizes automatic monitoring and collection of data, and realizes the simulation of the disturbance caused by soil sampling under pressure at different depths.

[0036] The diameter of the soil sample used in this embodiment is slightly larger than the diameter of the sampler.

[0037] The axial compression system includes a base 12, a porous insulating permeable stone 4, a sample cap 19, a screw 1, a steel frame 2, a lever frame 26, a weight 10 and a pore pressure sensor 27; the porous insulating permeable stone 4 is placed on the upper and lower surfaces of the soil sample 15, and the upper part is provided with a sample cap 19 and a screw 1; the screw 1 is connected to the lever frame 26 and the weight 10 through the steel frame 2;

[0038] The lateral insulating support system includes a high-strength insulating plastic 6, which is restrained on the outside by a steel guard ring 7 and in contact with a soil sample 15 through a rubber membrane 5 on the inside;

[0039] The hydraulic jacking sampling system includes a vertical rigid support 21, a screw rod 20, a hydraulic jack 14, a transmission 16, a coupling 17, and a controller 18. The screw rod 20 is connected to the hydraulic jack 14 and the transmission 16 through the coupling 17 and is vertically erected in the vertical rigid support 21. The controller 18 is connected to the hydraulic jack 14 through a cable. The transmission 16 is installed between the screw rod 20 and the hydraulic jack 14. The center point of the vertical rigid support 21 passes through the movable bolt 1. The sampler 3 is locked in the load platform 24 through the clamp 23, and the movable pull rod can move up and down. The slide rail 29 for carrying the clamp 23 to slide is arranged in the load platform 24. The clamp 23 locks or releases the sampler 3 by sliding. In this structure, the slide rail 29 is below the load platform 24 or embedded in the load platform 24.

[0040] The drainage control system includes a rubber membrane 5, a drainage pipe 9 and a clamp 11. The rubber membrane 5 is sleeved over the sample, the bottom end of the rubber membrane 5 is wrapped around the base 12 and fastened, the top end of the rubber membrane 5 is wrapped around the clamp 23, and the drainage pipe 9 is embedded in the base 12; an openable clamp 11 is arranged on the drainage pipe 9.

[0041] The resistivity acquisition and processing system includes a copper electrode 13 and a resistivity acquisition module 8. The resistivity acquisition module 8 can test the resistivity of the soil sample between the electrodes before and after the sampler 3 is pushed in, and evaluate the disturbance degree of soil sampling through the resistivity change.

[0042] The simulated in-situ soil sampling disturbance device and disturbance evaluation method include the following steps:

[0043] (1) Cut the original soil sample, place the porous insulating permeable stone 4, copper electrode 13, soil sample 15, copper electrode 13, porous insulating permeable stone 4 and sample cap 19 on the base 12 in sequence, connect the resistivity acquisition module 8 and pore pressure sensor 27, and align the screw 1 with the sample cap 19. Use rubber rings to tighten the two ends of the rubber film 5 to the base 12 and the sample cap 19 respectively. Lay high-strength insulating plastic 6 around the sample and tighten it with a steel guard ring 7. Adjust the bolt 1 to press the sample cap 19 and press the soil sample 15;

[0044] (2) The original soil is composed of soil particles, water and air. Different numbers of weights 10 are applied to simulate the compressed state of the soil at different depths. Different pressures are applied by different numbers of weights 10 to the screw 1. Under pressure, water passes through the porous insulating permeable stone 4 and the connected drainage pipe 9. The clamp 11 of the drainage pipe 9 is loosened to discharge the water in the compressed soil.

[0045] (3) Observe the pore pressure sensor 27 until the pore pressure of the soil sample is dissipated to zero, and clamp the drainage pipe 9 to stop draining. Start the resistivity acquisition device 8 to record the resistivity ρ1 of the soil sample;

[0046] (4) starting the servo hydraulic system 14 and the transmission 16, and pushing the sampler connected to the clamp 23 into the soil sample until the soil sample is completely cut;

[0047] (5) With the bolts supporting the sample cap 19, slowly lift the sampler 3 until the soil sample is completely separated from the sampler 3;

[0048] (6) Start the resistivity acquisition device 8 and record the resistivity ρ2 of the soil sample after it is cut. The disturbance degree of soil sampling is obtained through the changes in the resistivity twice. The disturbance degree is expressed as:

[0049]

[0050] The evaluation method of the simulated in-situ soil sampling disturbance device is based on the disturbance degree D of the soil sampling. When the disturbance degree D ≥ 10%, the soil sample is regarded as being significantly disturbed; when the disturbance degree D < 10%, it is regarded as being slightly disturbed.

[0051] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A disturbance evaluation method using a simulated in-situ soil sampling disturbance device, the in-situ soil sampling disturbance device comprising a high-strength insulating plastic for containing soil samples, the high-strength insulating plastic being arranged on a base, a drainage pipe connected to the high-strength insulating plastic being arranged in the base, a hydraulic jacking sampling system and an axial compression system being arranged above the high-strength insulating plastic; the hydraulic jacking sampling system being arranged in the axial compression system, a through hole for a screw to pass through being arranged at the center of the hydraulic jacking sampling system and the axial compression system, a sample cap being arranged at the bottom end of the screw, and the sample cap being arranged at the top of the soil sample; copper electrodes being arranged at the top and bottom ends of the soil sample in the high-strength insulating plastic, respectively, the copper electrodes at the top and bottom ends being connected to a resistivity acquisition module through a wire, and the copper electrode at the bottom end being connected to a pore pressure sensor through a wire; The hydraulic jacking sampling system and the axial compression system drive the screw to apply pressure to the soil sample in the high-strength insulating plastic, so that the pore pressure sensor and the resistivity acquisition module obtain corresponding data; The axial compression system includes porous insulating permeable stone, steel frame, lever frame, weights, and a stand; The steel frame is arranged on the platform, and the steel frame is composed of two parallel vertical rods, a horizontal rod on the top of the vertical rods, and a lever frame at the bottom of the vertical rods to form a frame structure, and the bottom end of the vertical rod passes through the platform and is connected to the lever frame; A tray for placing weights is provided on the lever frame, and the deadweight of the weights is used to move the steel frame downward, and drive the screw to drive the sample cap to apply pressure to the sample; The top and bottom of the soil sample of the high-strength insulating plastic are respectively arranged with porous insulating permeable stones; The hydraulic jacking sampling system includes a sampler, a vertical rigid support, a screw rod, a hydraulic jack, a transmission, a coupling, a controller, a clamp, a load platform, and a round nut; The vertical rigid support is arranged outside the high-strength insulating plastic container, and the height of the vertical rigid support is greater than the height of the high-strength insulating plastic container; The center of the sampler is consistent with the center of the vertical rigid support, the screw extends into the sampler, the sample cap is placed in the sampler, and the bottom of the sampler is placed on the outside of the sample cap; The hydraulic jack is connected to the coupling through a transmission, the coupling is connected to the screw rod, a controller is provided at the top of the screw rod, and the hydraulic jack, the coupling, the screw rod and the controller are vertically erected; The two ends of the load platform are respectively provided with circular nuts, and the circular nuts and the spiral rod form a threaded rotating part; the clamp is arranged on the load platform, and the clamp is used to clamp the sampler; The outer side of the high-strength insulating plastic is provided with a steel guard ring for restraint, and the inner side of the high-strength insulating plastic is in contact with the soil through a rubber film; the bottom end of the rubber film is wrapped around the base, and the top end of the rubber film is wrapped to the outer side of the bottom end of the sampler; The drain pipe is provided with a clip; Features: The perturbation evaluation steps are as follows: (1) Cut the original soil sample, and place the porous insulating permeable stone, copper electrode, soil sample, copper electrode, porous insulating permeable stone and sample cap on the base in sequence; connect the resistivity acquisition module and the pore pressure sensor, and align the bolts with the sample cap; use rubber rings to tighten the two ends of the rubber membrane to the base and the sample cap respectively; High-strength insulating plastic is laid around the sample and tightened with a steel guard ring, and the sample cap is pressed by adjusting bolts to tighten the soil sample; (2) Apply different numbers of weights to simulate the compressive state of the soil at different depths, and loosen the drainage clamp to drain the water in the compressed soil; (3) Observe the pore pressure sensor until the pore pressure of the soil sample is dissipated to zero, clamp the drainage pipe and stop draining, start the resistivity acquisition device, and record the resistivity ρ1 of the soil sample; (4) Start the hydraulic jack and transmission, and push the sampler connected to the fixture into the soil sample until the soil sample is completely cut; (5) With the bolts supporting the sample cap, slowly lift the sampler until the soil sample is completely separated from the sampler; (6) Start the resistivity acquisition device and record the resistivity ρ2 of the soil sample after it is cut. The disturbance degree of soil sampling is obtained through the changes in the resistivity twice. The disturbance degree is expressed as:

2. The evaluation method using the simulated in-situ soil sampling disturbance device according to claim 1 is characterized in that: According to the disturbance degree D obtained from soil sampling, when the disturbance degree D ≥ 10%, the soil sample is considered to be significantly disturbed; when the disturbance degree D < 10%, it is considered to be slightly disturbed.

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