CN105890961A - Sample preparation method and compaction device for immature soil base materials - Google Patents

Abstract

The invention discloses a sample preparation method of raw soil-based materials and a pressing device, comprising the steps of applying a layer of lubricating oil in a mold, layering the raw soil-based materials into the mold, laying each layer of raw soil-based materials, and pressing the raw soil-based materials by a jack. The raw soil-based material layer in the mold is compacted to obtain the sample to be tested; the compaction rate of the jack is 0.5mm/s, the compaction pressure of the jack is 18-19KN, and the compaction time of the jack is 3-5min; The device includes a test bench. The first platform and the second platform are arranged side by side along the horizontal direction from top to bottom in the test bench. On the second platform, jacks, gaskets, molds and pressure columns are coaxially arranged in sequence from bottom to top in the vertical direction. , the top of the pressure column is tightly pressed against the first platform. By comparing the traditional hammer test, press compaction test and jack compaction test, it can be seen that the compressive strength of the specimen compacted by the jack is higher than that of the other two test methods. The compressive strength of the solid specimen must be stable, the overall deformation of the specimen is better, and the specimen has better ductility under compression.

Description

A sample preparation method and pressing device for raw soil-based materials

technical field

The invention belongs to the field of building structures in the field of civil engineering, and specifically relates to a sample preparation method and a pressing device for raw soil materials.

Background technique

The compaction test is a method of hammering a soil sample to understand the compaction characteristics of the soil. This method is to use different compaction work (hammer weight × drop distance × hammering times) to hammer soil samples with different water contents, and measure the corresponding dry bulk density, so as to obtain the maximum dry bulk density and optimal water content, as Provide basis for design and construction of filling works. The traditional compaction test uses a cylindrical compaction bucket and a cylindrical gravity compaction hammer for layered compaction, but it is cumbersome to use, and human factors have a great influence on the test, and the efficiency is low.

Contents of the invention

In view of the defects and deficiencies in the prior art, the object of the present invention is to provide a sample preparation method and a pressing device for raw soil materials. The method and the mold improve the sample preparation efficiency of raw soil materials. control, reduce the influence of human factors on the sample preparation of raw soil materials, the degree of mechanization is higher, the use is simpler, and it is easy to promote.

In order to achieve the above object, the technical scheme that the present invention takes is:

A method for preparing samples of raw soil-based materials, comprising: applying a layer of lubricating oil in a mold, loading the raw soil-based materials into the mold in layers, laying each layer of raw soil-based materials, and lifting the raw soil-based materials in the mold by a jack The test sample is obtained by compacting the layers; the compaction rate of the jack is 0.5mm/s, the compaction pressure of the jack is 18-19KN, and the compaction time of the jack is 3-5min.

Further, let the prepared sample with the mold stand for a whole day and night before removing the mold, and the sample after the mold is removed is placed indoors for 28 days, the curing temperature is 20°C ± 5°C, and the curing humidity is 15% to 25%. .

Specifically, the sample shape of the prepared raw soil-based material is a cube.

The sample preparation method is realized by a pressing device, and the pressing device includes a test bench. The first platform and the second platform are arranged side by side along the horizontal direction from top to bottom in the test bench, and the second platform is vertically arranged from bottom to top on the second platform. A jack, a mold and a pressure column are arranged coaxially in sequence, and the top of the pressure column is tightly pressed against the first platform.

Further, a retaining hoop is arranged coaxially between the mold and the pressure column, the top end of the retaining hoop is sleeved outside the pressure column, the bottom end of the retaining hoop is sleeved outside the mould, and the pressure column passes through the retaining hoop to prevent the production in the mould. Soil base materials are compacted.

Specifically, the mold is a cube-shaped mold, the cross-section of the pressure column is square, and the cross-section of the retaining hoop is rectangular.

In detail, the length × width × height of the cube-shaped mold is 150 mm × 150 mm × 150 mm, the side length of the cross-section of the pressure column is 147 mm, and the length × width of the top cross-section of the retaining hoop is 180 mm × 150 mm. The length x width of the bottom cross section of the hoop is 200mm x 180mm.

Specifically, the manufacturing material of the pressure column and the retaining hoop is plexiglass, and the mold is a steel mold.

The pressing device for realizing the described sample preparation method includes a test bench. The first platform and the second platform are arranged side by side along the horizontal direction sequentially from top to bottom on the test bench, and are coaxial on the second platform vertically from bottom to top A jack, a mold and a pressure column are set, and the top of the pressure column is tightly pressed against the first platform.

The advantages of the present invention are:

(1) The sample preparation method of the raw soil-based material of the present invention uses a jack to compact every layer of the raw soil-based material layer in the mold to obtain the final sample, and through the compaction rate, compaction pressure and The research on the compaction time has obtained the preparation conditions that can ensure the overall performance of the final raw soil-based material sample is better, and by comparing the traditional hammer test, press compaction test and jack compression test, it can be seen that, The compressive strength of the specimen compacted by the jack is more stable than that of the specimens compacted by the other two test methods, the density of the specimen is good, and the cohesion between the soil particles is high. The data deviation of each specimen is the smallest. Comparing the peak displacement, it can be found that the overall deformation of the specimen compacted by the jack is better, and the specimen has better ductility when it is compressed;

(2) The pressing device for realizing the sample preparation method of the present invention includes a test bench, and the test bench is arranged side by side along the horizontal direction successively from top to bottom with a first platform and a second platform, and vertically from bottom to top on the second platform Set the jack, gasket, mold and pressure column coaxially in sequence. The top of the pressure column is pressed against the first platform, and the gasket and the mold are lifted up at a uniform speed by the jack, so that the pressure column at the top is pressed into the mold. The raw soil-based material in the sample is compacted to prepare the required sample, not only the production process is controllable, but also the production process is simple and easy to implement;

(3) because loose soil volume is bigger than the volume of compacted soil, so will be compacted into so big soil body of trial mold, when adding soil, there will be a part of soil body to expose outside trial mold, therefore, the present invention is compacted A retaining hoop is added between the column and the mold to hold the excess soil, which not only facilitates the sample preparation process, but also facilitates the accurate pressing of the column into the mold;

(4) The size of the top end of the retaining hoop of the present invention is different from the size of the bottom end, and the area of the bottom end is greater than the area of the top end, so that the bottom end is sleeved outside the mold and the top end is sleeved outside the pressure column, and the retaining hoop is a rectangular member. A certain gap can be left behind the square mold and the pressure column, and the air between the soil particles will be discharged during the compaction process, so that the compaction effect is better, and in order to prevent manufacturing deviation, ensure that the pressure column is pressed smoothly Into the retaining ring and mold;

(5) The production material of the pressure column and the retaining hoop of the present invention is plexiglass, the mold is a steel mold, and the gasket is a steel gasket. Utilizing the larger rigidity and better flatness of the plexiglass, the composition can be enclosed within The 150mm×150mm×150mm steel mould, which constrains the downward movement of the pressure column, has a smaller friction force between the plexiglass, and the plexiglass pressure column slides more smoothly in the plexiglass stop collar.

Description of drawings

Fig. 1 is the overall structure schematic diagram of the pressing device of raw earth-based material of the present invention;

Fig. 2 is the front view of the first baffle;

Fig. 3 is the right view of Fig. 2;

Fig. 4 is the top view of Fig. 2;

Fig. 5 is the front view of the second baffle;

Fig. 6 is the right view of Fig. 5;

Figure 7 is a top view of Figure 5;

The labels in the figure are represented as: 1-test bench, 11-first platform, 12-second platform, 13-anchor member, 2-jack, 3-mould, 4-block hoop, 41-first baffle plate, 42 -Second baffle, 5-pressure column;

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

detailed description

The sample preparation method of the raw soil-based material of the present invention comprises applying a layer of lubricating oil in the mould, packing the raw soil-based material into the mould, each layer of raw soil-based material is laid, and the raw soil-based material in the mold is lifted by a jack. The material layer is compacted; the compaction rate of the jack is 0.5mm/s, the compaction pressure of the jack is 18-19KN, and the compaction time of the jack is 3-5min. Let the prepared sample stand for a whole day and night before removing the mold. The sample after removing the mold is placed indoors for 28 days. The curing temperature is 20°C±5°C and the curing humidity is 15% to 25%. The sample shape of the prepared raw soil-based material is cubic.

In conjunction with Fig. 1, the pressing device for realizing the sample preparation method includes a test bench 1, the test bench 1 is provided with four columns perpendicular to the plane in four directions, and the test bench 1 is arranged side by side along the horizontal direction from top to bottom successively. First platform 11 and The second platform 12, the first platform 11 and the second platform 12 are respectively fixed on the four uprights by anchoring members 13, for example, the anchoring members 13 are bolts or flange members, on the second platform 12 vertically from bottom to top The jack 2, the mold 3 and the pressure column 5 are arranged coaxially in sequence, and the top of the pressure column 5 is pressed tightly against the first platform 11.

A retaining hoop 4 is coaxially arranged between the mold 3 and the pressure column 5, the top end of the retaining hoop 4 is sleeved outside the pressure column 5, the bottom end of the retaining hoop 4 is sleeved outside the mold 3, and the pressure column 5 passes through the retaining hoop 4. Compact the raw earth-based material in the mold 3.

The mold 4 is a cube-shaped mold, the cross-section of the pressure column 5 is square, and the cross-section of the retaining hoop 4 is rectangular. The length × width × height of the cube-shaped mold 3 is 150mm × 150mm × 150mm, the side length of the cross-section of the pressure column 5 is 147mm, the height of the pressure column 5 is 200mm, and the length × width of the top cross-section of the retaining hoop 4 is 180mm * 150mm, the length * width of the bottom cross-section of retaining hoop 4 is 200mm * 180mm.

The pressure column 5 and the retaining hoop 4 of the present invention are made of plexiglass material, and the plexiglass retaining hoop 4 is composed of four processed plexiglass baffles bonded to each other, as shown in Figure 2-7, the baffles include the first baffle The plate 41 and the second baffle 42, the bottom of the second baffle 42 is provided with a card slot, after assembly, the two first baffles 41 and the two second baffles 42 are inserted and fixed through the card slots; A space of 5mm is reserved at both ends along one direction between 5 and hoop 4, so that when the raw soil material is compacted, the air between the materials can be discharged from the gap, which is conducive to the compactness of the test piece. It is made of plexiglass with a thickness of about 15mm and a high rigidity. The height of retaining hoop 4 is just suitable for adding the amount of raw soil-based material for the last time, and should not be too high or too low, so that the quality of compaction can be maintained and materials can be saved.

Preferably, the present invention adopts the steel mold 3 of 150mm * 150mm * 150mm to carry out test research, and the structure of steel mold 3 is consistent with the structure of concrete test mold, adopts bolt to connect between coaming plate and base plate, in order to prevent mold expansion, relatively There is a card slot at the joint of the adjacent coaming plate; in order to facilitate the discharge of gas in the soil, there is a small gap at the joint between the coaming plate and the bottom plate. The jack adopted in the present invention is a manual hydraulic jack capable of measuring and displaying pressure, and can observe and adjust the compaction pressure.

Example 1:

As shown in Figure 1, taking a 150mm×150mm×150mm steel mold as an example, the pressing device for raw soil-based materials includes a test bench 1. The test bench 1 is provided with four columns perpendicular to the plane in four directions. The test bench 1 is from top to bottom. The first platform 11 and the second platform 12 are arranged side by side in the horizontal direction in turn, and the four columns pass through the first platform 11 and the second platform 12 and are respectively fixed by anchor members 13. The anchor members 13 are bolt members for tightening and fixing. On the second platform 12, a jack 2, a mold 3 and a pressure column 5 are coaxially arranged vertically from bottom to top in sequence, and the top of the pressure column 5 is tightly pressed against the first platform 11. A retaining hoop 4 is coaxially arranged between the mold 3 and the pressure column 5, the top end of the retaining hoop 4 is sleeved outside the pressure column 5, the bottom end of the retaining hoop 4 is sleeved outside the mold 3, and the pressure column 5 passes through the retaining hoop 4. Compact the raw earth-based material in the mold 3.

Mold 3 is a cube-shaped mold, and the plane area of its bottom surface is greater than the cross-section surrounded by side walls around. The cross-section of pressure column 5 is square, and the cross-section of retaining hoop 4 is rectangular. The side length of the cross-section of the pressure column 5 is 147mm, the height of the pressure column 5 is 200mm, the length × width of the top cross-section of the retaining hoop 4 is 180mm × 150mm, and the length × width of the bottom cross-section of the retaining hoop 4 is 200mm ×180mm.

The pressure column 5 and the retaining hoop 4 of this embodiment are made of plexiglass material, and the retaining hoop 4 is composed of four processed plexiglass baffles bonded to each other. See Figure 2-7 for details. The baffles include the first baffle 41 and the second baffle plate 42, the bottom end of the second baffle plate 42 is provided with a card slot, after assembly, the two first baffle plates 41 and the two second baffle plates 42 are inserted and fixed through the card slots; the pressure column 5 A space of 5 mm is reserved at both ends of the retaining hoop 4 along one direction. The retaining hoop 4 is bonded with a plexiglass with a thickness of about 15 mm and has a relatively high rigidity. The mold 3 is a steel mold or a plexiglass mould. , to meet the pressure requirements of the raw soil-based material compaction process.

Embodiment 2: the contrast of sample preparation method

Taking a cubic steel mold of 150mm×150mm×150mm as an example, the compressive strength of cubic raw soil-based material specimens prepared by three different manufacturing methods: traditional hammering method, press compaction method and jack compaction method Experimental analysis, study the size and appearance of the test piece after forming, the density of the test piece after forming, and the compressive strength of the test piece after 28 days. Observe the test failure form, the location of cracks, study the stress distribution state, and carry out statistical analysis and stability analysis on the data. Study the commonality and difference of the three production methods, and find out the more suitable production method of the cube specimen of raw soil material.

Traditional hammering method:

Put the cubic steel mold flat on a solid ground, install the casing, apply a thin layer of lubricating oil inside the cubic steel mold, compact the calculated soil volume three times, and pack the soil in layers For the light compaction test, the compaction work per unit volume is about 592.2kJ/m ³ , divided into three layers, and each layer is compacted 68 times. Ensure that the hammer falls freely and vertically in real time. The hammer traces must be evenly distributed on the surface of the soil sample. The sample of raw soil-based material is scraped flat;

Press compaction method:

Put the cubic steel mold flat on the platform of the pressure testing machine, the model of the pressure testing machine is MAS-500 servo actuator, manufactured by Hangzhou Weibang Electromechanical Control Engineering Co., Ltd., and coat a thin layer of For lubricating oil, load the calculated soil volume in three layers, each layer is 50mm. Put the mold filled with soil under the press, put the pressure column in the mold, and carry out geometric centering, then lower the pressure plate of the press, when the pressure plate and the plexiglass pressure column are just in contact, clear the press test range, and then start the test to let the press apply pressure downward at a rate of 0.1mm/s. The real-time pressure of the first lamination is about 27KN, the real-time pressure of the second lamination is about 32KN, and the real-time pressure of the third lamination is about It is 22KN. After one layer is pressed, let it stand still for 3 to 5 minutes, lift the pressing plate and take out the piston, roughen the contact surface of the soil sample in this layer, repeat the above steps to press, and after the compaction is completed, scrape the soil that exceeds the top of the mold test. Raw soil-based material samples.

Jack compaction method:

Utilize the pressing mold among the embodiment 1, apply one deck thinner lubricating oil in the cube steel mould, the soil amount calculated is divided into three layers and packs, and every layer of 50mm, after assembling the device, by jack with 0.5 Apply pressure at a constant rate of mm/s, and the compaction pressure of the jack is about 18-19KN. After one layer is pressed, stand still for 3-5 minutes, lower the jack, take out the test mold and roughen the contact surface of the soil sample in this layer, repeat Press the above steps, and after the compaction is completed, scrape off the soil that exceeds the height of the top form with a knife and smooth the surface to obtain a raw soil-based material sample.

The samples made by the above three methods were left to stand for a whole day and night, and then the steel mold was removed, and they were kept indoors for 28 days. The curing temperature was 20°C ± 5°C, and the curing humidity was 15% to 25%.

Put the sample that has been cured for 28 days under a 300KN press for a compression test. The compression test steps include:

(1) Test the sample in time after it is taken out from the curing place, and wipe the surface of the sample and the upper and lower pressure bearing plates with a dry towel;

(2) Place the test piece upright on the lower platen of the testing machine, adjust the position of the test piece so that its axis is aligned with the center of the lower platen;

(3) Start the testing machine, and when the upper pressing plate is close to the sample or the steel backing plate, make the contact balance and adjust the displacement to zero;

(4) The load should be applied continuously and evenly without impact, and the loading speed should be controlled at 1mm/min;

(5) Record the failure load and export the experimental data;

(6) Observe the damage state of the test piece, and take photos for archiving;

The obtained test data is processed, and the processing results are shown in Table 1 below.

Table 1 Results of compressive strength test

It can be seen from the data comparison that the compressive strength of the specimen compacted by the jack is higher than that of the specimen compacted by the press, but lower than that of the compacted specimen. It can be seen from the standard deviation that the compressive strength of the specimen compacted by the jack is more stable than that of the specimens compacted by the other two test methods, and the data deviation of the 10 specimens compacted by the jack is the smallest, compared with the peak displacement It can be found that the overall deformation of the specimen compacted by the jack is better, and the specimen has better ductility under compression.

Comparing the preparation method of the test piece, the test method and the test data, it is found that the jack compaction method is simpler to use, more efficient, better in compaction effect, and more conducive to promotion, and the compressive strength of the test piece compacted by the jack Higher, the strength is closer to the traditional compaction method, and the difference in compressive strength between the specimens is small, and the ductility is better.

Claims (10)

1. A sample preparation method of raw soil-based material, comprising smearing lubricating oil layer in the mould, raw soil-based material layered into the mould, it is characterized in that, every layer of raw soil-based material is paved, and the mold is pressed against the mold by a jack. The raw soil-based material layer inside is compacted to obtain the sample to be tested; the compaction rate of the jack is 0.5mm/s, the compaction pressure of the jack is 18-19KN, and the compaction time of the jack is 3-5min. 2. the sample preparation method of raw soil-based material as claimed in claim 1, is characterized in that, the sample with mold that will make leaves standstill one day and night and then removes mold, and the sample after removing mold is placed on indoor maintenance 28. day, the curing temperature is 20°C ± 5°C, and the curing humidity is 15% to 25%. 3. The sample preparation method of raw soil-based material according to claim 1 or 2, characterized in that, the shape of the sample of the prepared raw soil-based material is cubic. 4. the sample preparation method of raw earth-based material as claimed in claim 1 or 2, is characterized in that, this sample preparation method adopts pressing device to realize, and described pressing device comprises test stand (1), test stand (1) The first platform (11) and the second platform (12) are arranged side by side along the horizontal direction from top to bottom successively, and the jack (2) and the mold ( 3) and pressure column (5), the top of pressure column (5) is pressed against first platform (11). 5. the sample preparation method of raw soil-based material as claimed in claim 4, is characterized in that, between mold (3) and pressure post (5), also coaxially sets retaining collar (4), retaining collar (4) The top of the top is socketed outside the pressure column (5), the bottom end of the retaining hoop (4) is socketed outside the mold (3), and the pressure column (5) passes through the retaining hoop (4) against the raw soil in the mold (3). The base material is compacted. 6. the sample preparation method of raw earth-based material as claimed in claim 4, is characterized in that, described mold (3) is steel mold or plexiglass mold. 7. the sample preparation method of raw soil-based material as claimed in claim 5, is characterized in that, described mold (3) is the mold of cube shape, and the cross-section of pressure column (5) is square, and retaining hoop (4 ) is rectangular in cross-section. 8. the sample preparation method of raw soil-based material as claimed in claim 7, is characterized in that, the length * width * height of described cube-shaped mold (3) is 150mm * 150mm * 150mm, and pressure column (5) The side length of the cross-section is 148mm, and the length * width of the top cross-section of the retaining hoop (4) is 180mm * 150mm, and the length * width of the bottom cross-section of the retaining hoop (4) is 200mm * 180mm. 9. The sample preparation method of raw soil-based material as claimed in claim 5, characterized in that, the manufacturing material of the pressure column (5) and the retaining hoop (4) is plexiglass. 10. realize the pressing device of claim 1, 2 or 3 described sample preparation methods, it is characterized in that, comprise test stand (1), test stand (1) arranges first platform ( 11) and the second platform (12), the jack (2), the mold (3) and the pressure column (5) are arranged coaxially on the second platform (12) vertically from bottom to top, and the pressure column (5) The top of the top is tight with the first platform (11).