CN108663249B - A kind of preparation device and preparation method of cohesion-free soil sample for geotechnical test - Google Patents

Abstract

The invention discloses a preparation device and a preparation method of a cohesive soil sample for a geotechnical test. The device comprises a sample filling part, a sample compacting part, a sample pre-saturation part and a vacuum pumping part; the sample filling part includes The first split mold, the second split mold, the bottom collar, the top collar, two ring hoops, two rubber rings and the rubber film; the present invention makes the rubber film tightly attached to the first mold by vacuuming. The inner walls of the split mold and the second split mold help to reduce the defects on the side of the sample and ensure the uniformity of the side of the sample; the bottom collar improves the bottom stability of the sample loading part, and the top collar has It helps to reduce the loss of soil sample mass and the pollution to the geotechnical test device during the sample preparation process of the top sample; After determining the size of the solid part, it can be used for the preparation of non-cohesive soil samples for different precision geotechnical tests.

Description

A kind of preparation device and preparation method of cohesion-free soil sample for geotechnical test

technical field

The invention relates to the technical field of indoor geotechnical tests of geotechnical engineering, in particular to a device for preparing cohesive-free soil samples for geotechnical tests and a preparation method thereof.

Background technique

Indoor geotechnical testing is one of the main ways to reveal various physical and mechanical properties of soil, and it can provide a scientific basis for the determination of soil parameters in the process of engineering design, theory or numerical calculation.

Indoor geotechnical tests are carried out based on suitable soil unit samples. The undisturbed soil is sampled in situ and then cut. The samples required for the test can be obtained directly. In the case of large sampling disturbance, difficult sampling, or limited number of original samples, difficult to transport and store, etc., remolded soil is usually used for systematic and detailed indoor geotechnical test research.

Existing studies have shown that when remolded soil is used for indoor geotechnical tests, the sample preparation quality of soil unit samples has a significant impact on the results and accuracy of precision geotechnical tests, especially for the use of precision soil unit test devices ( Indoor geotechnical tests such as GDS advanced triaxial/dynamic triaxial test device, GDS resonance column test device, etc.). Because cohesive soils generally have relatively large cohesion, remolded soil samples have good overall stability, and the required cohesive soil sample preparation molds can be purchased directly, and obtained through mature consolidation or compaction techniques. Specimens required for soil testing. However, cohesionless soil (such as sand) has almost no cohesive force, and the soil has the characteristics of loose grains. If scientific sample preparation molds and effective sample preparation measures are not taken, it is difficult to obtain the cohesion required for indoor geotechnical tests. Cohesive soil samples. In addition, if the cohesionless soil sample is separated from the geotechnical sample device, it is very easy to cause different degrees of damage to the cohesionless soil sample, which will affect the quality of the sample preparation and the accuracy of the subsequent test. Therefore, it is recommended that the cohesionless soil The sample is directly prepared on the sample installation base of the geotechnical sample device.

At present, there is no universally recognized and unified cohesion-free soil sample preparation device. The cohesion-free soil sample preparation device in the existing literature and patents still has the following three shortcomings: (1) The double-lobe mold used is directly placed on the geotechnical test sample. On the sample installation base of the sampling device, no protection measures are taken for the connection between the double-lobe mold and the sample installation base, and it cannot be guaranteed that the impact of the double-lobe mold on the double-lobe mold and the compacted sample during the sample preparation process of non-cohesive soil will be guaranteed. The impact of the connection with the sample mounting base may affect the uniformity of the bottom of the prepared sample and the coincidence and connection of the central axis of the sample and the sample mounting base; (2) During the sample preparation process of non-cohesive soil, no auxiliary impact In other words, it cannot guarantee the consistent falling height of the compaction, nor can it locate the compaction area of the compaction hammer during each compaction (there may be eccentric compaction), which will have an adverse effect on the uniformity of sample preparation; (3) double The top of the flap mold is flush with the top of the sample, and no measures are taken to assist the top soil sample preparation. The height of the top soil filling exceeds the height of the double flap mold. On the one hand, the quality of the poured soil sample may be lost during the compaction process And pollute the geotechnical test device. On the other hand, in order to reduce the loss of sample quality, the soil on the top surface of the general sample will be poured in the top center area of the sample as much as possible, resulting in uneven soil density in the top layer of the sample. In fact, taking the GDS resonant column test as an example, the axial and radial displacement sensors of the sample are installed on the top area of the sample, and the sample preparation quality of the top layer of the sample will directly affect the test. In order to overcome the above shortcomings, it is necessary to develop a precise non-cohesive soil sample preparation device and a preparation method thereof that are effectively connected to the sample mounting base of the geotechnical sample device.

Contents of the invention

In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides a preparation device and test preparation method of cohesion-free soil samples for geotechnical tests.

The technical solution adopted by the present invention to solve the technical problems is: a preparation device for cohesive soil samples for geotechnical tests, including a sample filling part, a sample compaction part, a sample pre-saturation part and a vacuum pumping part; The sample filling part includes a first split mold, a second split mold, a bottom collar, a top collar, a first annular hoop, a second annular hoop, a first rubber ring, a second rubber ring, and a rubber film; The inner walls of the first pair of molds and the second pair of molds are provided with air guide grooves; the middle part of the second pair of molds is provided with air holes; 1. The second ring hoop is aligned and connected up and down, and the cross-section after the two are connected is a complete circle; after the first pair of molds and the second pair of molds are connected, they are vertically around the base of the soil unit sample through the bottom collar. Installed on the base of the geotechnical test instrument; the base of the geotechnical test instrument has a valve connected to the bottom of the sample; the top collar is installed on the top of the first split mold and the second split mold for sample filling connection between the part and the compacted part of the specimen;

The rubber film is flatly attached to the inner walls of the first split mold and the second split mold, one end is placed on the base of the soil unit sample and fixed by the first rubber ring, and the other end is placed on the first split mold And the outer wall of the top of the second split mold and fixed by the second rubber ring;

The sample compaction part includes a compaction sleeve, a compaction hammer and a compaction rod; the compaction sleeve has a compaction sleeve scale line, and the compaction rod has a compaction rod scale line; The zero scale line of the solid sleeve is located at the bottom of the scale line of the compaction sleeve, and the zero scale line of the compaction rod is located at the top of the scale line of the compaction rod; the bottom of the compaction sleeve is detachably connected with the top collar; The solid bar is orthogonally connected to the center of the compaction hammer; driven by the compaction bar, the compaction hammer can move up and down in the cavity formed by the compaction sleeve, the first pair of molds and the second pair of molds. The sample is compacted; the top cap of the soil unit sample is installed on the top surface of the compacted sample, and the top cap of the soil unit sample has a top cap through pipe;

The sample pre-saturation part is composed of a vacuum pre-saturation fitting, a water pre-saturation fitting and a carbon dioxide gas tank; the vacuum pre-saturation fitting includes a first plexiglass cylinder, a first plexiglass base, a first air inlet / water inlet valve, first negative pressure gauge, cap, vacuum valve, air vent; the first plexiglass cylinder is sealed and connected to the cap through a rubber ring; the bottom of the first plexiglass cylinder is connected to the first plexiglass base connection, the first plexiglass base is equipped with a first air inlet/water inlet valve and a first negative pressure gauge; the first air inlet/water inlet valve is connected to the top cap through pipe; the cap has a vent and is provided with a suction Vacuum valve;

The water pre-saturated accessories include a second plexiglass cylinder, a second plexiglass base, a second air intake/water inlet valve, and a second negative pressure gauge; the top of the second plexiglass cylinder is open ; The bottom of the second plexiglass cylinder is connected with the second plexiglass base; the second plexiglass base is equipped with a second air inlet/water inlet valve and a second negative pressure gauge; the second air inlet/water inlet valve passes through the pipeline Connect the valve connected to the bottom of the sample on the base of the geotechnical test instrument;

The carbon dioxide gas tank is connected to the valve at the bottom of the sample on the base of the geotechnical test instrument through a pipeline;

The vacuum part includes a vacuum pump with a vacuum pressure control valve, and the vacuum pump is respectively connected to the air guide grooves on the inner walls of the first split mold and the second split mold, and the vent on the cap.

Further, the cut surface at the junction of the first split mold and the second split mold is smooth, and the joint of the first split mold and the second split mold is smooth through the first annular hoop and the second annular hoop. Sealed connection; the first ring hoop is installed near the bottom 1/3 height of the first half mold and the second half mold; the second ring hoop is installed near the first half mold and the second half mold 1/3 of the height of the mold top.

Further, the material of the first split mold, the second split mold, the bottom collar and the top collar is wear-resistant metal, including stainless steel and aluminum alloy; the first ring hoop and the second ring hoop The material of the compacting sleeve is stainless steel; the material of the compacting sleeve is transparent organic glass; the material of the compacting hammer and the compacting rod is brass or stainless steel.

Further, the height of the first split mold and the second split mold is the sum of the height of the sample and the height of the soil unit sample base; the first split mold and the second split mold with rubber film after butt joint The inner diameter of the mold is equal to the diameter of the sample; the bottom of the first split die and the second split die has a notch to accommodate the soil unit sample base and the first rubber ring, and the notch size is determined by the thickness of the rubber film and The diameter of the first rubber ring is determined; the outer diameter of the first split mold and the second split mold near the top/height range is less than the outer diameter near the bottom 2/3 height range;

The inner diameter of the bottom collar is determined by the bottom outer diameter of the first split mold and the second split mold after butt joint; the opening diameter of the top collar is equal to the sample diameter; the inner diameter of the top collar is determined by the butt joint The outer diameter of the top of the first pair of molds and the second pair of molds, and the thickness of the rubber film are determined;

The inner diameter of the sleeve of the compaction sleeve is equal to the sample diameter; the inner diameter of the bottom ring of the compaction sleeve is equal to the outer diameter of the top collar; the inner height of the compaction sleeve is determined by the height of the sample, the compaction hammer The height and the drop distance of the compaction sample are determined; the top center of the compaction sleeve has a circular hole, and the diameter of the circular hole is determined by the diameter of the sample, the diameter of the compaction hammer and the diameter of the compaction rod; The diameter of the compaction hammer is determined by the diameter of the specimen.

Further, the air guide grooves on the inner walls of the first pair of open molds and the second pair of open molds have the following two types:

The first type of air guide grooves are annular air guide grooves arranged in parallel along the inner walls of the first split mold and the second split mold, and the annular air guide grooves communicate with the air holes through linear grooves.

The second type of air guiding groove is a helical air guiding groove along the inner walls of the first and second split molds, and the helical air guiding groove passes through the air hole.

A method for preparing a cohesive-free soil sample for a geotechnical test, the method comprising the following steps:

(1) After the first pair of open molds and the second pair of open molds are aligned up and down, the side walls are sealed and connected through the first ring hoop and the second ring hoop;

(2) Fix one end of the rubber membrane on the base of the soil unit sample through the first rubber ring; then, surround the soil unit sample with the butt-connected first and second split molds through the bottom collar The base is vertically installed on the base of the geotechnical test instrument; then straighten the rubber membrane so that the other end is placed on the outer wall of the top of the first pair of molds and the second pair of molds that have been docked; The way of vacuumizing the air guide groove on the inner wall of the second split mold makes the rubber membrane flatly adhere to the inner walls of the first split mold and the second split mold, and the other end of the rubber membrane is fixed on the second rubber ring. The outer wall of the top of the butted first pair of molds and the second pair of molds;

(3) Install the top collar horizontally on the top of the butted first half mold and the second half mold with rubber film, so that the top collar and the rubber film, the first half mold and the second half mold The outer wall of the sample is tightly connected to complete the installation of the sample filling part;

(4) Design test soil sample layered filling test plan: fill in n layers, the weight of the soil sample for each layer of filling m=M/n, the height of the soil sample for each layer of filling l=L/n, Among them, M is the total weight of the sample, L is the height of the sample;

(5) Install the compaction rod and the compaction sleeve with the compaction hammer in sequence to the sample loading part, read the scale reading _a1 of the compaction rod corresponding to the zero scale line of the compaction sleeve; remove the compaction sleeve in turn After the compaction rod with the compaction hammer, pour the first layer of soil sample with a weight of m into the sample loading part; install the compaction rod and the compaction sleeve with the compaction hammer again, so that the compaction sleeve The inner wall of the inner wall of the top collar opening is aligned with the inner walls of the butted first and second half molds with rubber membranes; the compaction hammer touches the top surface of the uncompacted first layer of filling soil , read the scale reading of the compaction rod corresponding to the zero scale line of the compaction sleeve as b _1+k , where k represents the number of compactions; take k=0 before compaction, that is, the compaction rod corresponding to the zero scale line of the compaction sleeve The scale reading of the solid rod is b ₁ ;

(6) Use a compaction rod with a compaction hammer to compact the first layer of filled soil, each time the compaction hammer falls at a distance of l ₀ , that is, the compaction rod corresponds to the zero scale line of the compaction sleeve The scale of the scale is (b _1+k +l ₀ ); during the first compaction, the compaction rod falls from the scale corresponding to the zero scale line of the compaction sleeve (b ₁ +l ₀ ); multiple compactions The final compaction height of the first layer of filled soil is l, that is, when the compaction hammer touches the top surface of the compacted first layer of filled soil, the scale of the compaction rod corresponding to the zero scale line of the compaction sleeve Reading a ₂ =a ₁ +l; ensure that the top surface of the filling soil layer is evenly leveled before and after each compaction;

(7) After scraping the surface of the first layer of filled soil with a bamboo stick, pour a second layer of soil sample with a weight of m into the sample filling part, and compact the second layer of filled soil. Reciprocate in this way until the compaction of the sample with a height of L is completed;

(8) After removing the compaction sleeve, the compaction rod with the compaction hammer, the top collar and the second rubber ring in turn, install the top cap of the soil unit sample on the top surface of the sample evenly and horizontally, so that the soil unit The central axis of the top cap of the body sample coincides with the line connecting the central axis of the sample; turn up the rubber film on the top outer wall of the first split mold and the second split mold and put it on the top cap and pass it through the second rubber ring fixed;

(9) Use the vacuum part and the vacuum pre-saturation accessories to assist the mold removal. First, close the valve on the base of the geotechnical test instrument connected to the bottom of the sample, and connect the first air/water inlet valve at the bottom of the vacuum pre-saturation accessories to the top cap. Connect the through pipe, and then connect the vent port on the top of the vacuum pre-saturation fitting to the vacuum pump with a vacuum pressure control valve; after injecting anaerobic water into the first plexiglass cylinder, connect the first plexiglass cylinder and the The cap is sealed and connected; close the vacuum pressure control valve, open the first air inlet/water inlet valve, the vacuum valve and the valve controlling the top cap through pipe, start the vacuum pump, and slowly adjust the vacuum pressure control valve until the vacuum pressure is stably maintained at - 20kPa; After the sample is vertically stabilized by the applied negative pressure, remove the first ring hoop and the second ring hoop, the first pair of molds and the second pair of molds, and the bottom collar respectively; controlled by the vacuum pressure control valve The vacuum pressure is stably maintained at -20kPa, so that the sample remains stable, and an unsaturated soil sample is obtained;

(10) Pre-saturation step: After connecting the control valve of the carbon dioxide gas tank to the valve connected to the bottom of the sample on the base of the geotechnical test instrument, open the control valve of the carbon dioxide gas tank and the valve connected to the bottom of the sample on the base of the geotechnical test instrument, Slowly inject carbon dioxide into the sample; adjust the control valve of the carbon dioxide gas tank to make the air bubbles in the first plexiglass cylinder uniform and slow; control the vacuum pressure at -20kPa through the vacuum pressure control valve, and continuously and slowly flow into the sample After passing the carbon dioxide gas for 30 minutes, close the valve connected to the bottom of the sample on the base of the geotechnical test instrument and the control valve of the carbon dioxide gas tank;

Close the second air/water inlet valve at the bottom of the water pre-saturation fitting, inject a sufficient amount of anaerobic water into the second plexiglass cylinder, remove the gas in the connecting conduit, and connect the base of the geotechnical test instrument through the connecting conduit. The valve at the bottom of the sample is connected to the second air inlet/water inlet valve; open the valve on the base of the geotechnical test instrument to connect the valve at the bottom of the sample with the second air inlet/water inlet valve, and under the action of vacuum pressure, the second plexiglass cylinder The air-free water in the sample will be slowly injected into the sample; the vacuum pressure is controlled at -20kPa by the vacuum pressure control valve, and the air-free water is continuously injected into the sample; until the air bubbles in the first plexiglass cylinder completely disappear Finally, close the valve connected to the bottom of the sample on the base of the geotechnical test instrument and the valve controlling the top hat through pipe, the first air/water inlet valve and the second air/water inlet valve, and the vacuum pump to obtain a saturated soil sample. .

Further, the rubber film is evacuated to the air guide grooves on the inner walls of the first split mold and the second split mold by a vacuum pump, so that it is flatly attached to the first split mold and the second split mold. Inner wall: During the layered filling process of the sample, the rubber film is continuously and flatly attached to the inner walls of the first split mold and the second split mold.

Further, during the soil sample compaction process, the central axis of each component of the sample filling part and the sample compaction part, the central axis of the sample and the central axis of the soil unit sample base are kept coincident; compaction of the sample.

Further, the formula for calculating the total mass of the sample is In the formula, d, L, e, ω and _ds are the diameter, height, void ratio, water content and soil particle weight of the sample respectively, and _ρw is the density of water; where the value of ω is determined by the sample preparation method, When preparing a saturated soil sample, if wet stamping method is used for sample preparation, ω is 5%; if (dry sand) falling sand method is used for sample preparation, ω is 0; when unsaturated soil sample is prepared, ω is the sample Actual moisture content.

Furthermore, when the scale reading of the compaction rod corresponding to the zero scale line of the compaction sleeve exceeds the maximum scale a _max of the compaction rod, that is, when the compaction hammer enters the compaction sleeve, the final The compaction height is based on the fact that when the compaction hammer touches the top surface of the compacted soil, the scale of the compaction sleeve corresponding to the maximum scale a _max of the compaction rod is (a _n+1 = a _n + la _max ), wherein, n represents the number of layered filling of the sample;

Each time the soil sample is compacted, the compaction rod falls from the position where the scale line of the compaction sleeve corresponding to the maximum scale a _max of the compaction rod is (b _1+k +l ₀ −a _max ).

Compared with prior art, the beneficial effect of the present invention:

1. In the present invention, the inner walls of the first pair of molds and the second pair of molds are provided with connected air guide grooves, and the rubber film is flatly attached to the first pair of molds and the second pair of molds by vacuuming. The inner wall helps to reduce the defects on the side of the sample, effectively ensuring the uniformity of the side of the sample.

2. The arrangement of the bottom collar in the present invention improves the bottom stability of the sample filling part, contributes to the tight connection between the double-lobe mold and the sample mounting base, and reduces the knocking of the double-lobe mold and the knocking on the non-cohesive soil sample preparation process. Realize the influence of the sample on the connection between the double-lobe mold and the sample mounting base, ensure the uniformity of the soil at the bottom of the sample, and keep the central axes of the sample and the sample mounting base coincident during the preparation process.

3. The top collar is set in the present invention, which is used for the connection of the sample filling part and the sample compacting part on the one hand; The quality loss of the soil sample and the pollution to the geotechnical test device during the sampling process ensure the uniformity and flatness of the soil in the top area of the sample, and improve the sample preparation quality in the top area of the sample; set the top collar, the bottom collar, and the second One pair of open molds and the second pair of open molds are designed with a variable cross-section near the top 1/3, which helps to improve the overall stability of the sample loading part.

4. The compacting sleeve, the scale line of the compacting sleeve and the scale line of the compacting rod in the compacting part of the present invention belong to auxiliary compaction measures, and the compacting sleeve is used to guide the compaction hammer and position the compaction hammer. In the solid area, the scale line of the compaction sleeve and the scale line of the compaction rod are used to determine the drop height of the compaction hammer, supplemented by the quincunx compaction method, which will effectively ensure the uniformity of sample preparation.

5. The pre-saturation step in the present invention helps to improve the sample preparation efficiency of the saturated soil sample, and will effectively shorten the time required for sample saturation in the test.

6. The pre-saturation part and the vacuum part in the present invention have versatility. After adjusting the size of the sample filling part and the sample compaction part according to the geotechnical test device and the sample size, it can be used for non-stickiness of different precision geotechnical tests. Soil samples.

Description of drawings

Fig. 1 (a) is the top view of the first pair of open molds;

Fig. 1 (b) is the front view of the first pair of open molds;

Fig. 1 (c) is the side view of the first pair of dies;

Fig. 2 (a) is the top view of the second pair of molds;

Fig. 2 (b) is the front view of the second pair of molds;

Fig. 2 (c) is the side view of the second pair of molds;

Fig. 3 is the schematic diagram of the first type of air guide groove;

Fig. 4 is the schematic diagram of the second type air guide groove;

Figure 5(a) is a top view of the bottom collar;

Figure 5(b) is a front view of the bottom collar;

Fig. 5 (c) is the A-A sectional view of the bottom collar;

Figure 6(a) is a top view of the top collar;

Figure 6(b) is a front view of the top collar;

Fig. 6 (c) is the B-B sectional view of top collar;

Fig. 7 is a schematic diagram of a compacting rod with a compacting hammer;

Figure 8(a) is a top view of the compaction sleeve;

Figure 8(b) is a front view of the compaction sleeve;

Figure 8(c) is a C-C sectional view of the compaction sleeve;

Fig. 9 (a) is the exploded schematic view of the vacuum pre-saturation accessories;

Figure 9 (b) is a front view of the vacuum pre-saturation fitting;

Figure 9(c) is a top view of the vacuum pre-saturation fitting;

Figure 10 (a) is a front view of the water pre-saturation fitting;

Figure 10(b) is a top view of the water pre-saturation fitting;

Figure 11(a) is a front view after the assembly of the sample filling part and the sample compacting part;

Figure 11(b) is a cross-sectional view of the assembly of the sample filling part and the sample compaction part;

Fig. 12 is a sample schematic diagram of installing the top cap of the soil unit sample before removing the formwork;

In the figure: sample loading part 1, first pair of molds 1-1, second pair of molds 1-2, circular air guide groove 1-2-1, linear groove 1-2-2, spiral wire guide Air groove 1-2-3, air hole 1-2-4, bottom collar 1-3, top collar 1-4, first ring hoop 1-5, second hoop 1-6, first rubber ring 1-7, second rubber ring 1-8, rubber film 1-9, sample compaction part 2, compaction sleeve 2-1, compaction sleeve scale line 2-2, compaction sleeve zero scale line 2-2-1, compaction hammer 2-3, compaction rod 2-4, compaction rod scale line 2-5, compaction rod zero scale line 2-5-1, vacuum pre-saturation accessories 3, the first Plexiglass cylinder 3-1, first plexiglass base 3-2, first air/water inlet valve 3-3, first negative pressure gauge 3-4, cap 3-5, vacuum valve 3-6, Air vent 3-7, water pre-saturation fitting 4, second plexiglass cylinder 4-1, second plexiglass base 4-2, second air/water inlet valve 4-3, second negative pressure gauge 4 -4. Soil unit sample base 5, soil unit sample top cap 6, top cap through pipe 6-1, geotechnical test instrument base 7.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

A preparation device for cohesion-free soil samples for geotechnical tests provided by the present invention comprises a sample filling part 1, a sample compacting part 2, a sample pre-saturation part and a vacuum pumping part; the sample filling part 1 includes a first One pair of open dies 1-1, second pair of open dies 1-2, bottom collar 1-3, top collar 1-4, first ring hoop 1-5, second ring hoop 1-6, first rubber Ring 1-7, second rubber ring 1-8, rubber film 1-9; as shown in Figure 1 (a)-Figure 1 (c), Figure 2 (a)-Figure 2 (c), the first The inner walls of the split mold 1-1 and the second split mold 1-2 are provided with air guide grooves; the middle part of the second split mold 1-2 is provided with air holes 1-2-4; the first split mold The mold 1-1 and the second split mold 1-2 are aligned and connected up and down through the first annular hoop 1-5 and the second annular hoop 1-6, and the section after the two join is a complete circle; the second A pair of split molds 1-1 and the second pair of split molds 1-2 are connected and installed vertically on the soil unit sample base 5 around the soil unit sample base 5 through the bottom collar 1-3, and the bottom collar 1-3 The structure of Fig. 5 (a)-shown in Fig. 5 (c); The valve that communicates with the bottom of the sample is arranged on the base 7 of the geotechnical test instrument; The top collar 1-4 is installed on the first split mold 1- 1 and the top of the second split mold 1-2, which are used to connect the sample filling part 1 and the sample compacting part 2, and the structure of the bottom collar 1-3 is shown in Figure 6(a)-Figure 6(c) shown.

The rubber membrane 1-9 is flatly attached to the inner walls of the first split mold 1-1 and the second split mold 1-2, and one end is set on the soil unit sample base 5 and passed through the first rubber ring 1 -7 is fixed, and the other end is sleeved on the outer wall of the first split mold 1-1 and the second split mold 1-2 top and is fixed by the second rubber ring 1-8.

The sample compaction part 2 includes a compaction sleeve 2-1, a compaction hammer 2-3 and a compaction rod 2-4; the compaction sleeve 2-1 has a compaction sleeve scale line 2- 2. The compacting rod 2-4 has a compacting rod scale line 2-5; the compacting sleeve zero scale line 2-2-1 is located at the bottom of the compacting sleeve scale line 2-2, and the compacting rod zero The scale line 2-5-1 is located at the top of the compaction rod scale line 2-5; the structure of the compaction sleeve 2-1 is shown in Figure 8(a)-Figure 8(c); the compaction sleeve 2 The bottom of -1 is detachably connected to the top collar 1-4; the compacting rod 2-4 is orthogonally connected to the center of the compacting hammer 2-3, as shown in Figure 7; the compacting hammer 2-3 Driven by the compacting rod 2-4, it can move up and down in the cavity formed by the compacting sleeve 2-1, the first split mold 1-1 and the second split mold 1-2, and compact the sample ; The structural diagram of the sample loading part 1 and the sample compaction part 2 after assembly is shown in Figure 11(a) and Figure 11(b). Install the top cap 6 of the soil unit sample on the top surface of the compacted sample, and the top cap 6 of the soil unit sample has a top cap through pipe 6-1, as shown in FIG. 12 .

The sample pre-saturation part is composed of a vacuum pre-saturation fitting 3, a water pre-saturation fitting 4 and a carbon dioxide gas tank; as shown in Figure 9(a)-Fig. 9(c), the vacuum pre-saturation fitting 3 Including the first plexiglass cylinder 3-1, the first plexiglass base 3-2, the first air/water inlet valve 3-3, the first negative pressure gauge 3-4, the cap 3-5, and the vacuum valve 3 -6. Air vent 3-7; the first plexiglass cylinder 3-1 is sealed and connected to the cap 3-5 through a rubber ring; the bottom of the first plexiglass cylinder 3-1 is connected to the first plexiglass base 3- 2 connection, the first plexiglass base 3-2 is equipped with the first air inlet/water inlet valve 3-3 and the first negative pressure gauge 3-4; the first air inlet/water inlet valve 3-3 is connected with the top hat 6-1 connection; the cap 3-5 has a vent 3-7 and is provided with a vacuum valve 3-6.

As shown in Figure 10(a) and Figure 10(b), the water pre-saturation fitting 4 includes a second plexiglass cylinder 4-1, a second plexiglass base 4-2, a second air/water inlet Valve 4-3, second negative pressure gauge 4-4; the top of the second plexiglass cylinder 4-1 is open; the bottom of the second plexiglass cylinder 4-1 is connected to the second plexiglass base 4 -2 connection; the second plexiglass base 4-2 is equipped with a second air inlet/water inlet valve 4-3 and a second negative pressure gauge 4-4; the second air inlet/water inlet valve 4-3 is connected by pipeline The valve on the base 7 of the geotechnical testing instrument communicates with the bottom of the sample.

The carbon dioxide tank is connected to the valve on the bottom of the sample on the base 7 of the geotechnical testing instrument through a pipeline.

The vacuum part includes a vacuum pump with a vacuum pressure control valve, and the vacuum pump is respectively connected to the air guide groove on the inner wall of the first split mold 1-1 and the second split mold 1-2, and the vent on the cap 3-5 3-7.

Further, the cut surface at the junction of the first split mold 1-1 and the second split mold 1-2 is smooth, and the first pair of ring hoops 1-5 and second ring hoops 1-6 make the The joint between the split mold 1-1 and the second split mold 1-2 is sealed; the first ring hoop 1-5 is installed near the first split mold 1-1 and the second split mold 1- 2 at the bottom 1/3 of the height; the second ring hoop 1-6 is installed near the top 1/3 of the first split mold 1-1 and the second split mold 1-2.

Further, the first split mold 1-1, the second split mold 1-2, the bottom collar 1-3, and the top collar 1-4 are made of wear-resistant metal, including stainless steel, aluminum alloy The material of the first annular hoop 1-5 and the second annular hoop 1-6 is stainless steel; the material of the compacting sleeve 2-1 is transparent plexiglass; the compacting hammer 2-3, compacting The solid rods 2-4 are made of brass or stainless steel.

Further, the height of the first split mold 1-1 and the second split mold 1-2 is the sum of the height of the sample and the height of the soil unit sample base 5; The inner diameter of the first split mold 1-1 and the second split mold 1-2 is equal to the diameter of the sample; the bottom of the first split mold 1-1 and the second split mold 1-2 has a soil unit The notch of the body sample base 5 and the first rubber ring 1-7, the size of the notch is determined by the thickness of the rubber film 1-9 and the diameter of the first rubber ring 1-7; the first split mold 1-1 And the outer diameter near the top 1/3 height range of the second split mold 1-2 is smaller than the outer diameter near the bottom 2/3 height range.

The inner diameter of the bottom collar 1-3 is determined by the bottom outer diameter of the first split mold 1-1 and the second split mold 1-2 after docking; the opening diameter of the top collar 1-4 is equal to the test sample diameter; the inner diameter of the top collar 1-4 is determined by the top outer diameter of the first split mold 1-1 and the second split mold 1-2 after butt joint, and the thickness of the rubber film 1-9.

The sleeve inner diameter of the compacting sleeve 2-1 is equal to the sample diameter; the inner diameter of the bottom ring of the compacting sleeve 2-1 is equal to the outer diameter of the top collar 1-4; the compacting sleeve 2- The internal height of 1 is determined by the height of the sample, the height of the compaction hammer 2-3 and the drop distance of the compacted sample; the top center of the compaction sleeve 2-1 has a circular hole 2-1-1, so The diameter of the circular hole 2-1-1 is determined by the diameter of the sample, the diameter of the compaction hammer 2-3 and the diameter of the compaction rod 2-4; the diameter of the compaction hammer 2-3 is determined by the diameter of the sample.

Further, the air guide grooves on the inner walls of the first split mold 1-1 and the second split mold 1-2 have the following two types:

As shown in Figure 3, the first type of air guiding groove is a circular air guiding groove 1-2-1 arranged in parallel along the inner walls of the first split mold 1-1 and the second split mold 1-2. The annular air guide groove 1-2-1 communicates with the air hole 1-2-4 through the linear groove 1-2-2.

As shown in Figure 4, the second type of air guide groove is a spiral air guide groove 1-2-3 along the inner wall of the first split mold 1-1 and the second split mold 1-2, and the spiral air guide groove Slot 1-2-3 passes through vent hole 1-2-4.

A method for preparing a cohesive-free soil sample for a geotechnical test, the method comprising the following steps:

(1) After the first pair of molds 1-1 and the second pair of molds 1-2 are aligned up and down, the side walls are sealed and connected through the first ring hoop 1-5 and the second ring hoop 1-6;

(2) One end of the rubber membrane 1-9 is fixed on the soil unit sample base 5 through the first rubber ring 1-7; 1-2 is vertically installed on the base of the geotechnical test instrument 7 around the soil unit sample base 5 through the bottom collar 1-3; then straighten the rubber membrane 1-9 so that the other end is placed on the first butt-connected pair On the outer wall of the top of the mold 1-1 and the second mold 1-2; the rubber is evacuated by a vacuum pump to the air guide grooves on the inner walls of the mold 1-1 and the mold 1-2 of the second mold After the membrane 1-9 is flatly attached to the inner walls of the first split mold 1-1 and the second split mold 1-2, the other end of the rubber membrane 1-9 is fixed on the butt joint by the second rubber ring 1-8. The outer wall of the top of the first split mold 1-1 and the second split mold 1-2;

(3) Install the top collar 1-4 horizontally on the top of the first split mold 1-1 and the second split mold 1-2 with rubber film 1-9 that have been joined together, so that the top collar 1-4 It is tightly connected with the outer wall of the rubber film 1-9, the first split mold 1-1 and the second split mold 1-2, and the installation of the sample filling part 1 is completed;

(4) Design test soil sample layered filling test plan: fill in n layers, the weight of the soil sample for each layer of filling m=M/n, the height of the soil sample for each layer of filling l=L/n, Among them, M is the total weight of the sample, L is the height of the sample, generally n=5;

(5) Install the compacting rod 2-4 and the compacting sleeve 2-1 with the compacting hammer 2-3 in sequence to the sample loading part 1, and read the corresponding value of the zero scale line 2-2-1 of the compacting sleeve. The scale reading a ₁ of the compaction rod 2-4; after removing the compaction sleeve 2-1 and the compaction rod 2-4 with the compaction hammer 2-3 in sequence, pour the sample with a weight of m into the sample filling part 1 The first layer of soil sample; Install the compacting rod 2-4 and the compacting sleeve 2-1 with the compacting hammer 2-3 again, so that the inner wall of the compacting sleeve 2-1 and the top collar 1-4 are open Align the inner walls of the butted first half mold 1-1 and the second half mold 1-2 with the rubber film 1-9; the compaction hammer 2-3 contacts the uncompacted first layer of filling On the top surface of the soil, read the scale reading of the compaction rod 2-4 corresponding to the zero scale line 2-2-1 of the compaction sleeve as b _1+k , where k represents the number of compactions; before compaction, take k= 0, that is, the scale reading of the compacting rod 2-4 corresponding to the zero scale line 2-2-1 of the compacting sleeve is _b1 ;

(6) Use the compaction rod 2-4 with the compaction hammer 2-3 to compact the first layer of filling soil, each time the compaction hammer 2-3 falls at a distance of l ₀ , that is, the compaction rod 2-4 falls from the zero scale line 2-2-1 of the compaction sleeve at (b _1+k +l ₀ ); during the first compaction, the compaction rod 2-4 falls from the zero line of the compaction sleeve. The scale line 2-2-1 corresponds to the drop at (b ₁ +l ₀ ); the final compaction height of the first layer of filled soil after multiple compactions is l, that is, the contact pressure of the compaction hammer 2-3 When filling the top surface of the first layer of solid soil, the scale reading of the compaction rod 2-4 corresponding to the zero scale line 2-2-1 of the compaction sleeve a ₂ =a ₁ +l; guarantee each compaction The top surfaces of the front and rear filling soil layers are uniform and level;

(7) After scraping the surface of the first layer of filled soil with a bamboo stick, pour the second layer of soil sample with a weight of m into the sample filling part 1, and compact the second layer of filled soil , reciprocating in this way until the compaction of the sample with a height of L is completed;

(8) After successively removing the compaction sleeve 2-1, the compaction rod 2-4 with the compaction hammer 2-3, the top collar 1-4 and the second rubber ring 1-8, the uniform level of the sample The soil unit sample top cap 6 is installed on the top surface so that the central axis of the soil unit sample top cap 6 coincides with the connection line of the sample central axis; the first pair of molds 1-1 and the second pair of The rubber film 1-9 on the top outer wall of mold opening 1-2 is flipped up and put on the top cap 6 and fixed by the second rubber ring 1-8;

(9) Use the vacuum part and the vacuum pre-saturation accessory 3 to assist in demoulding, first close the valve on the base 7 of the geotechnical test instrument connected to the bottom of the sample, and the first air/water inlet valve at the bottom of the vacuum pre-saturation accessory 3 3-3 is connected to the top hat through pipe 6-1, and then the vent 3-7 on the top of the vacuum pre-saturation fitting 3 is connected to the vacuum pump with a vacuum pressure control valve; inject in the first plexiglass cylinder 3-1 After air-free water, the first plexiglass cylinder 3-1 is sealed with the cap 3-5 through a rubber ring; the vacuum pressure control valve is closed, and the first air/water inlet valve 3-3 and vacuum valve 3 are opened -6 and control the valve of the top hat through pipe 6-1, start the vacuum pump, slowly adjust the vacuum pressure control valve until the vacuum pressure is stably maintained at -20kPa; after the sample is vertically stable by the applied negative pressure, remove the first One ring hoop 1-5 and the second ring hoop 1-6, the first split mold 1-1 and the second split mold 1-2, the bottom collar 1-3; the vacuum pressure is controlled stably by the vacuum pressure control valve Maintain at -20kPa, so that the sample remains stable, and an unsaturated soil sample with a water content of ω and a void ratio of e is prepared;

(10) Pre-saturation step: After connecting the control valve of the carbon dioxide gas tank to the valve connected to the bottom of the sample on the base 7 of the geotechnical test instrument, open the control valve of the carbon dioxide gas tank and the valve connected to the bottom of the sample on the base 7 of the geotechnical test instrument , slowly inject carbon dioxide into the sample; adjust the control valve of the carbon dioxide tank so that the bubbles in the first plexiglass cylinder 3-1 are uniform and slow; the vacuum pressure is controlled stably at -20kPa by the vacuum pressure control valve, and the continuous slow After passing carbon dioxide gas into the sample for 30 minutes, close the valve connected to the bottom of the sample and the control valve of the carbon dioxide gas tank on the base 7 of the geotechnical test instrument;

Close the second air/water inlet valve 4-3 at the bottom of the water pre-saturation fitting 4, inject a sufficient amount of anaerobic water into the second plexiglass cylinder 4-1, remove the gas in the connecting conduit, and pass through the connecting conduit Connect the valve connected to the bottom of the sample on the base 7 of the geotechnical test instrument with the second air intake/water inlet valve 4-3; open the valve connected to the bottom of the sample on the base 7 of the geotechnical test instrument and the second air inlet/water inlet valve 4 -3. Under the action of vacuum pressure, the air-free water in the second plexiglass cylinder 4-1 will be slowly injected into the sample; the vacuum pressure is controlled by the vacuum pressure control valve to maintain it stably at -20kPa, and continue to test Inject anaerobic water into the sample; after the air bubbles in the first plexiglass cylinder 3-1 completely disappear, close the valve connected to the bottom of the sample on the base 7 of the geotechnical test instrument and the valve controlling the top cap tube 6-1, the first One air inlet/water inlet valve 3-3 and the second air inlet/water inlet valve 4-3, vacuum pump to prepare a saturated soil sample with void ratio e.

Further, the rubber membrane 1-9 is evacuated to the air guide grooves on the inner walls of the first split mold 1-1 and the second split mold 1-2 through a vacuum pump, so that it is flatly attached to the first pair of split molds. The inner wall of the split mold 1-1 and the second split mold 1-2; during the layered filling process of the sample, the rubber film 1-9 is continuously and flatly attached to the first split mold 1-1 and the second split mold. Divide the inner wall of mold 1-2.

Further, during the soil sample compaction process, the central axis of each component of the sample filling part 1 and the sample compacting part 2, the central axis of the sample and the central axis of the soil unit sample base 5 are kept coincident ; The sample is compacted in a quincunx-shaped way.

Further, the formula for calculating the total mass of the sample is In the formula, d, L, e, ω and _ds are the diameter, height, void ratio, water content and soil particle weight of the sample respectively, and _ρw is the density of water; where the value of ω is determined by the sample preparation method, When preparing a saturated soil sample, if wet stamping method is used for sample preparation, ω is 5%; if (dry sand) falling sand method is used for sample preparation, ω is 0; when unsaturated soil sample is prepared, ω is the sample Actual moisture content.

Further, when the scale reading of the compaction rod 2-4 corresponding to the zero scale line 2-2-1 of the compaction sleeve exceeds the maximum scale a _max of the compaction rod 2-4, that is, the compaction hammer 2-3 enters the compaction When the sleeve 2-1 is used, the final compaction height of each layered soil mass is based on the compaction hammer 2-3 contacting the top surface of the compacted soil mass, the maximum compaction rod 2-4 The scale line scale of the compaction sleeve 2-1 corresponding to the scale a _max is determined by (a _n+1 = a _n + la _max ), where n represents the number of layered filling of the sample;

Each time the soil sample is compacted, the scale line scale of the compaction sleeve 2-1 corresponding to the maximum scale a _max of the compaction rod 2-4 from the compaction rod 2-4 is (b _1+k +l ₀ -a _max ) falls.

The above describes the technical principles of the present invention in conjunction with specific embodiments. These descriptions are only for explaining the principles of the present invention, and cannot be construed as limiting the protection scope of the present invention in any way. Based on the explanations herein, those skilled in the art can think of other specific implementation modes of the present invention without creative efforts, and these modes will all fall within the protection scope of the present invention.

Claims (8)

1. a preparation device for a cohesive soil sample for a geotechnical test, characterized in that: comprise a sample filling part (1), a sample compaction part (2), a sample presaturated part and a vacuum pumping part; The sample filling part (1) includes the first split mold (1-1), the second split mold (1-2), the bottom collar (1-3), the top collar (1-4), the first ring hoop (1-5), second annular hoop (1-6), first rubber ring (1-7), second rubber ring (1-8) and rubber membrane (1-9); said first pair The inner wall of the mold opening (1-1) and the second mold opening (1-2) is provided with an air guide groove; the middle part of the second mold opening (1-2) is provided with a ventilation hole (1-2-4) ; The first split mold (1-1) and the second split mold (1-2) are connected up and down by the first ring hoop (1-5) and the second ring hoop (1-6), both The cross-section after joining is a complete circle; the first split mold (1-1) and the second split mold (1-2) are connected and surround the soil unit body through the bottom collar (1-3) The sample base (5) is installed vertically on the base of the geotechnical test instrument (7); the valve of the bottom of the test sample is provided on the base of the geotechnical test instrument (7); the top collar (1-4) is installed on the A pair of open molds (1-1) and the top of the second pair of open molds (1-2), used for connecting the sample filling part (1) and the sample compacting part (2); The rubber film (1-9) is flatly attached to the inner walls of the first split mold (1-1) and the second split mold (1-2), and one end is sleeved on the soil unit sample base (5) and fixed by the first rubber ring (1-7), the other end is sleeved on the outer wall of the top of the first split mold (1-1) and the second split mold (1-2) and passed through the second rubber ring (1 -8) Fixed; The sample compaction part (2) comprises a compaction sleeve (2-1), a compaction hammer (2-3) and a compaction rod (2-4); the compaction sleeve (2-1) There is a compaction sleeve scale line (2-2) on the top, and the compaction rod (2-4) has a compaction rod scale line (2-5); the compaction sleeve zero scale line (2-2-1 ) is located at the bottom of the compaction sleeve scale line (2-2), and the compaction rod zero scale line (2-5-1) is located at the top of the compaction rod scale line (2-5); the compaction sleeve ( The bottom of 2-1) is detachably connected to the top collar (1-4); the compacting rod (2-4) is orthogonally connected to the center of the compacting hammer (2-3); the compacting hammer ( 2-3) Driven by the compacting rod (2-4), the compacting sleeve (2-1), the first split mold (1-1) and the second split mold (1-2) can form a move up and down in the cavity to compact the sample; the top cap (6) of the soil unit sample is installed on the top surface of the compacted sample, and the top cap (6) of the soil unit sample has a top cap through pipe (6-1); The sample pre-saturation part is composed of a vacuum pre-saturation fitting (3), a water pre-saturation fitting (4) and a carbon dioxide gas tank; the vacuum pre-saturation fitting (3) includes a first plexiglass cylinder (3 -1), the first plexiglass base (3-2), the first air/water inlet valve (3-3), the first negative pressure gauge (3-4), the cap (3-5), the vacuum valve (3-6) and air vent (3-7); Described first plexiglass cylinder (3-1) is sealed and connected with cap (3-5) by rubber ring; The first plexiglass cylinder (3-1 ) is connected with the first plexiglass base (3-2), and the first plexiglass base (3-2) is equipped with the first air inlet/water inlet valve (3-3) and the first negative pressure gauge (3- 4); the first air/water inlet valve (3-3) is connected to the top cap through pipe (6-1); the cap (3-5) has a vent (3-7) and is provided with a vacuum Valve (3-6); The water pre-saturation accessory (4) includes a second plexiglass cylinder (4-1), a second plexiglass base (4-2), a second air/water inlet valve (4-3) and a second Negative pressure gauge (4-4); The top of the second plexiglass cylinder (4-1) is open; the bottom of the second plexiglass cylinder (4-1) and the second plexiglass base (4 -2) connection; the second plexiglass base (4-2) is equipped with a second air inlet/water inlet valve (4-3) and a second negative pressure gauge (4-4); the second air inlet/water inlet valve (4-3) Connect the valve connected to the bottom of the sample on the base of the geotechnical test instrument (7) through a pipeline; The carbon dioxide gas tank is connected to the valve at the bottom of the sample on the base (7) of the geotechnical test instrument through a pipeline; The vacuum pumping part includes a vacuum pump with a vacuum pressure control valve, and the vacuum pump is respectively connected to the air guide groove and the cap (3- 5) the upper air vent (3-7); The cutting surface at the junction of the first split die (1-1) and the second split die (1-2) is smooth, and the first ring hoop (1-5), the second ring hoop (1-6) ) so that the junction of the first split mold (1-1) and the second split mold (1-2) is sealed; the first ring hoop (1-5) is installed near the first split mold (1-1) and the bottom 1/3 height of the second split mold (1-2); the second ring hoop (1-6) is installed near the first split mold (1-1) and the second At the top 1/3 height of the split mold (1-2); The height of the first split mold (1-1) and the second split mold (1-2) is the sum of the height of the sample and the height of the soil unit sample base (5); the belt rubber film ( 1-9) The inner diameter of the first pair of dies (1-1) and the second pair of dies (1-2) is equal to the diameter of the sample; the first pair of dies (1-1) and the second pair of dies The bottom of the mold opening (1-2) has a notch to accommodate the soil unit sample base (5) and the first rubber ring (1-7), and the size of the notch is determined by the thickness of the rubber film (1-9) and the first The diameter of the rubber ring (1-7) is determined; the outer diameter of the first split mold (1-1) and the second split mold (1-2) near the top 1/3 height range is smaller than the bottom 2/ 3 outside diameter within the height range; The inner diameter of the bottom collar (1-3) is determined by the bottom outer diameter of the first split mold (1-1) and the second split mold (1-2) after butt joint; the top collar (1 -4) the opening diameter is equal to the sample diameter; the inner diameter of the top collar (1-4) is formed by the top of the first split mold (1-1) and the second split mold (1-2) after butt joint The outer diameter and the thickness of the rubber film (1-9) are determined; The inner diameter of the sleeve of the compaction sleeve (2-1) is equal to the sample diameter; the inner diameter of the bottom ring of the compaction sleeve (2-1) is equal to the outer diameter of the top collar (1-4); the The internal height of the compaction sleeve (2-1) is determined by the height of the sample, the height of the compaction hammer (2-3) and the drop distance of the compacted sample; the top of the compaction sleeve (2-1) There is a circular hole (2-1-1) in the center, and the diameter of the circular hole (2-1-1) is determined by the diameter of the sample, the diameter of the compaction hammer (2-3) and the diameter of the compaction rod (2-4). Determine; the diameter of the compaction hammer (2-3) is determined by the diameter of the sample. 2. the preparation device of a kind of geotechnical test non-cohesive soil sample according to claim 1, is characterized in that: described first split mold (1-1), second split mold (1-2), The material of the bottom collar (1-3) and the top collar (1-4) is wear-resistant metal, including stainless steel and aluminum alloy; the first annular hoop (1-5), the second annular hoop (1 -6) is made of stainless steel; the material of the compacting sleeve (2-1) is transparent plexiglass; the material of the compacting hammer (2-3) and the compacting rod (2-4) is yellow Copper or stainless steel. 3. the preparation device of a kind of cohesionless soil sample for geotechnical test according to claim 1, is characterized in that: described first split mold (1-1) and the second split mold (1-2) inner wall The air guide groove has the following two types: The first type of air guide groove is an annular air guide groove (1-2-1) arranged in parallel along the inner walls of the first split mold (1-1) and the second split mold (1-2). The circular air guide groove (1-2-1) communicates with the air hole (1-2-4) through the linear groove (1-2-2); The second type of air guide groove is a helical air guide groove (1-2-3) along the inner walls of the first split mold (1-1) and the second split mold (1-2), and the spiral air guide groove The slots (1-2-3) pass through the vent holes (1-2-4). 4. a preparation method of cohesionless soil sample for geotechnical test, is characterized in that, the method may further comprise the steps: (1) After aligning the first pair of dies (1-1) and the second pair of dies (1-2) up and down, proceed through the first ring hoop (1-5) and the second ring hoop (1-6) Side wall seal connection; (2) One end of the rubber film (1-9) is fixed on the soil unit sample base (5) through the first rubber ring (1-7); 1) and the second split mold (1-2) are vertically installed on the soil test instrument base (7) around the soil unit sample base (5) through the bottom collar (1-3); then straighten the rubber film (1-9), make its other end be enclosed within on the outer wall of the first split mold (1-1) and the second split mold (1-2) top that butt; By vacuum pump to the first split mold ( 1-1) and the air guide groove on the inner wall of the second pair of molds (1-2) are vacuumed so that the rubber film (1-9) is flatly attached to the first pair of molds (1-1) and the second pair of molds After opening the inner wall of the mold (1-2), the other end of the rubber film (1-9) is fixed to the first butted mold (1-1) and the second mold by the second rubber ring (1-8). Split the outer wall of mold (1-2) top; (3) Install the top collar (1-4) horizontally on the top of the first split mold (1-1) and the second split mold (1-2) with the rubber film (1-9) connected , so that the top collar (1-4) is tightly connected with the rubber film (1-9), the outer walls of the first split mold (1-1) and the second split mold (1-2), and the sample filling is completed the installation of part (1); (4) Design test soil sample layered filling test plan: fill in n layers, the weight of the soil sample for each layer of filling m=M/n, the height of the soil sample for each layer of filling l=L/n, Among them, M is the total weight of the sample, L is the height of the sample; (5) Install the compaction rod (2-4) and the compaction sleeve (2-1) with the compaction hammer (2-3) in order to the sample loading part (1), and read the zero scale of the compaction sleeve The scale reading a ₁ of the compacting rod (2-4) corresponding to the line (2-2-1); remove the compacting sleeve (2-1) and the compacting rod (2-3) with the compacting hammer (2-3) in sequence After 2-4), pour the first layer of soil sample with a weight of m into the sample loading part (1); install the compaction rod (2-4) and the compaction hammer (2-3) with the compaction hammer (2-3) again Sleeve (2-1), so that the inner wall of the compacted sleeve (2-1), the inner wall of the opening of the top collar (1-4) and the butt jointed first split mold with rubber film (1-9) (1-1) is aligned with the inner wall of the second pair of molds (1-2); the compaction hammer (2-3) touches the top surface of the uncompacted first layer of filling soil, and reads the compaction sleeve The scale reading of the compaction rod (2-4) corresponding to the zero scale line (2-2-1) is b _1+k , k represents the number of compactions; take k=0 before compaction, that is, the compaction sleeve is zero The scale reading of the compacting rod (2-4) corresponding to the scale line (2-2-1) is _b1 ; (6) Adopt the compaction bar (2-4) of band compaction hammer (2-3) to compact the first layer of filling soil, every time compaction, the falling distance of compaction hammer (2-3) is l ₀ , that is, the compacting rod (2-4) falls from the zero scale line (2-2-1) of the compacting sleeve corresponding to b _1+k +l ₀ ; when compacting for the first time, the compacting rod ( 2-4) Drop from the zero scale line (2-2-1) of the compaction sleeve where the scale corresponding to b ₁ +l ₀ ; after multiple compactions, the final compaction height of the first layer of filled soil is l , that is, when the compaction hammer (2-3) touches the top surface of the first layer of compacted soil, the compaction rod (2-4) corresponding to the zero scale line (2-2-1) of the compaction sleeve The scale reading a ₂ =a ₁ +l; ensure that the top surface of the filling soil layer is evenly leveled before and after each compaction; (7) After scraping the surface of the first layer of filled soil with a bamboo stick, pour a second layer of soil sample with a weight of m into the sample filling part (1), and compact the second layer of filling Soil body, reciprocate in this way until the compaction of the sample with a height of L is completed; (8) Remove the compaction sleeve (2-1), compaction rod (2-4) with compaction hammer (2-3), top collar (1-4) and second rubber ring (1- 8) After that, install the top cap (6) of the soil unit sample on the top surface of the uniform sample, so that the central axis of the top cap (6) of the soil unit sample coincides with the line connecting the central axis of the sample; The rubber film (1-9) that is enclosed within the top outer wall of the first split mold (1-1) and the second split mold (1-2) turns up and is enclosed within on the top cap (6) and passes through the second rubber ring ( 1-8) fixed; (9) Use the vacuum part and the vacuum pre-saturation accessory (3) to assist in demolition. First, close the valve connected to the bottom of the sample on the base of the geotechnical test instrument (7), and place the first valve at the bottom of the vacuum pre-saturation accessory (3). The air inlet/water inlet valve (3-3) is connected to the top hat pipe (6-1), and then the air port (3-7) on the top of the vacuum presaturation fitting (3) is connected to the vacuum pump with a vacuum pressure control valve. Connection; after injecting airless water in the first plexiglass cylinder (3-1), the first plexiglass cylinder (3-1) is sealed and connected with the cap (3-5) by a rubber ring; the vacuum pressure is controlled The valve is closed, open the first air inlet/water inlet valve (3-3), the vacuum valve (3-6) and the valve controlling the top hat through pipe (6-1), start the vacuum pump, and slowly adjust the vacuum pressure control valve to The vacuum pressure is maintained stably at -20kPa; after the sample is vertically stabilized by the applied negative pressure, the first ring hoop (1-5) and the second ring hoop (1-6), the first half-open mold (1-1) and the second split mold (1-2), the bottom collar (1-3); through the vacuum pressure control valve, the vacuum pressure is stably maintained at -20kPa, so that the sample remains stable, and a non- Saturated soil samples; (10) Pre-saturation step: After connecting the control valve of the carbon dioxide gas tank to the valve connected to the bottom of the sample on the base of the geotechnical test instrument (7), open the control valve of the carbon dioxide gas tank and the base of the geotechnical test instrument (7) to connect the test sample. Slowly inject carbon dioxide into the sample through the valve at the bottom of the sample; adjust the control valve of the carbon dioxide gas tank to make the bubbles in the first plexiglass cylinder (3-1) uniform and slow; control the vacuum pressure through the vacuum pressure control valve to maintain stable At -20kPa, after continuously and slowly passing carbon dioxide gas into the sample for 30 minutes, close the valve connected to the bottom of the sample and the control valve of the carbon dioxide gas tank on the base of the geotechnical test instrument (7); Close the second air/water inlet valve (4-3) at the bottom of the water pre-saturation fitting (4), inject a sufficient amount of anaerobic water into the second plexiglass cylinder (4-1), and drain the connecting conduit Inner gas, connect the valve connected to the bottom of the sample on the base of the geotechnical test instrument (7) with the second air/water inlet valve (4-3) through the connecting conduit; open the base of the geotechnical test instrument (7) to connect to the bottom of the sample The valve and the second air inlet/water inlet valve (4-3), under the action of vacuum pressure, the air-free water in the second plexiglass cylinder (4-1) will be slowly injected into the sample; through the vacuum The pressure control valve controls the vacuum pressure to be stably maintained at -20kPa, and continuously injects anaerobic water into the sample; after the air bubbles in the first plexiglass cylinder (3-1) completely disappear, close the base of the geotechnical testing instrument (7) in sequence The valve connected to the bottom of the sample and the valve controlling the top hat through pipe (6-1), the first air/water inlet valve (3-3) and the second air/water inlet valve (4-3), vacuum pump , to prepare saturated soil samples. 5. the preparation method of a kind of geotechnical test non-cohesive soil sample according to claim 4, is characterized in that: described rubber film (1-9) is to the first pair of mold (1-1) by vacuum pump and The method of vacuumizing the air guide groove on the inner wall of the second split mold (1-2) makes it evenly close to the inner walls of the first split mold (1-1) and the second split mold (1-2); During the layered filling process of the sample, the rubber film (1-9) is continuously and flatly attached to the inner walls of the first split mold (1-1) and the second split mold (1-2). 6. the preparation method of a kind of geotechnical test non-cohesive soil sample according to claim 4 is characterized in that: in the soil sample compaction process, described sample filling part (1) and sample compaction part (2 ) keep coincident with the central axis of each component, the central axis of the sample, and the central axis of the soil unit sample base (5); the sample is compacted in a quincunx-shaped manner. 7. the preparation method of a kind of geotechnical test non-cohesive soil sample according to claim 4, is characterized in that: the calculation formula of sample gross mass is In the formula, d, L, e, ω and _ds are the diameter, height, void ratio, water content and soil particle weight of the sample respectively, and _ρw is the density of water; where the value of ω is determined by the sample preparation method, When preparing a saturated soil sample, ω is 5% if the wet stamping method is used for sample preparation; ω is 0 if the falling sand method is used for sample preparation; when preparing an unsaturated soil sample, ω is the actual water content of the sample. 8. the preparation method of a kind of geotechnical test cohesive-free soil sample according to claim 4, is characterized in that: when compaction sleeve zero scale line (2-2-1) corresponding compaction bar (2-4 ) scale reading exceeds the maximum scale a _max of the compaction rod (2-4), that is, when the compaction hammer (2-3) enters the compaction sleeve (2-1), the final The compaction height _is determined according to the compaction sleeve (2-1 ) is determined by a _n+1 = a _n + la _max , where n represents the number of layered fillings of the sample; When compacting the soil sample each time, the scale line scale of the compaction sleeve (2-1) corresponding to the maximum scale a _max of the compaction rod (2-4) from the compaction rod (2-4) is b _1+k +l ₀ -a _max drop.