CN105181416A - High-visualization geotechnical triaxial test sample device and manufacturing method - Google Patents

Abstract

A highly visualized geotechnical triaxial test sample preparation device and a sample preparation method. The geotechnical triaxial test sample preparation device includes two parts: a double valve and a collar. The double valve is a tempered glass split cylinder with a scale, which is axially divided into two parts that can be tightly combined: split half-tube A and split half-tube B. After the split half tube A and the split half tube B are assembled, two connecting seams are formed, perpendicular to the connecting seam, and scale lines are set on both sides of the split half tube. A vacuum suction hole is provided on the split half tube A and a rubber suction catheter is connected, so that the rubber membrane covers and clings to the inner surface of the double valve. The collar is made of stainless steel and is provided with connecting bolts to tighten the double valve. The assembly of the sample device is convenient and fast. The height of the sample preparation can be precisely controlled through the scale line on the double valve, and the vacuum pumping makes the rubber membrane close to the inner side of the double valve to ensure that the diameter of the sample is consistent along the height. The sample density is relatively uniform, and more reliable geotechnical triaxial test data can be obtained.

Description

A highly visualized geotechnical triaxial test sample device and sample preparation method

technical field

The invention belongs to the technical field of civil engineering equipment, and relates to a sample preparation device for a geotechnical triaxial test and a method for preparing a sample for a geotechnical triaxial test.

Background technique

The four pillars of soil mechanics are theoretical soil mechanics, experimental soil mechanics, applied soil mechanics and computational soil mechanics. As the foundation of the development of soil mechanics, experimental soil mechanics is not only based on repetitive tests based on sampling, fabrication, and simulation of influencing factors, but must be closely integrated with theoretical soil mechanics. With the improvement of soil mechanics theory and geotechnical experiment technology, geotechnical triaxial test has become a commonly used method to measure soil mechanical parameters.

When conducting soil tests, the STDTTS standard stress path triaxial instrument produced by the British GDS company is widely used in various universities and scientific research institutions. However, GDS did not provide a unified sample preparation device, and different researchers developed different sample preparation devices according to the test requirements and purposes. Conventional soil sample preparation molds are straight and assembled. When making samples in the straight cylinder mold, pour the soil sample into the straight cylinder mold, and then compact it layer by layer to the required height of the sample, and then push the sample out with the help of external force. Assembled type is to disassemble the above-mentioned straight cylinder mold in the axial direction and divide it into several pieces for reassembly. When preparing the sample, the parts are spliced into a cylinder, and iron rings are used to fix it outside the cylinder, and the soil is layered and compacted. Then take off the iron ring and break off the mold.

However, during the sample preparation process, conventional sample preparation devices are made of metal materials, which cannot intuitively judge and control the sample loading height. For soil mechanics tests that require strict control of the diameter and height of the sample, the same sample can only be obtained through the repeated process of "sample loading-measurement-sample removal".

Therefore, it is very necessary to design a reasonable geotechnical triaxial test sample preparation device to prepare more standardized geotechnical triaxial test samples; at the same time, it has certain practical significance for the improvement of the complete set of triaxial test equipment. The invention has the beneficial effects that: the triaxial test sample preparation mold has a simple structure, is convenient and practical, can be quickly assembled and disassembled, has good integrity after assembly, and has a good sample preparation effect.

Contents of the invention

The object of the present invention is to provide a geotechnical triaxial test sample preparation device, which can accurately control the height of the sample and make a triaxial sample with relatively uniform compactness.

The object of the present invention is also to provide a preparation method of a geotechnical triaxial test sample.

In order to achieve the above purpose, the technical solution adopted in the present invention is a highly visualized geotechnical triaxial test sample device and sample preparation method, wherein, a geotechnical triaxial test sample preparation device includes two parts: a double valve and a collar, The double valve is used to control the sample, and the collar is used to adjust the compactness of the sample. The ring is placed on the outer surface of the double valve; the double valve is axially divided into two parts that can be tightly sealed: the split half tube A and Split half barrel B. The double valve is made of tempered glass. The double valve is divided into upper, middle and bottom three parts. The bottom of the double valve is the part where the double valve is combined with the test instrument base, and its height is consistent with the height of the instrument base. The middle part of the double valve is the part that forms the sample, and the height of the middle part of the double valve meets the requirement that the ratio of the height to the diameter of the prepared sample is 2.0-2.5. The upper part of the double valve is the part for placing and fixing the sample cap. In order to facilitate the fixation of the rubber membrane and the binding of the rubber band, the inner diameters of the bottom and upper parts of the double valve are larger than the inner diameters of the middle part, and the outer diameters of the upper part and the middle part are connected through a smooth transition.

The double valves are scaled and symmetrical to each other. The split half tube A and the split half tube B are assembled to form a connecting seam, the scale is perpendicular to the connecting seam, and the two sides of the split half tube A and the split half tube B are provided with scale lines (3) respectively. The zero point of the scale line (3) is located on the top of the permeable stone on the base of the pressure chamber, and its minimum value is 1mm.

In the middle of the double valve, a vacuum suction hole (1) made of tempered glass is arranged in the middle of the split half tube A and connected to a rubber suction catheter (2), so that the rubber membrane covers and clings to the inner surface of the double valve.

The collar is made of stainless steel, and the collar includes a collar body (4), a connecting bolt shank, and a connecting bolt (5); the collar body (4) is provided with a connecting bolt shank and a connecting bolt (5). Adjust the connecting bolt (5) to realize the locking degree of the connecting bolt rod.

A method for preparing a geotechnical triaxial test sample: the preparation method includes the following steps: step 1: assembling double valves; step 2: filling soil samples; step 3: removing double valves; specifically, this step includes the following detailed steps,

Step one, assemble the double valve. First put permeable stones and filter paper on the base of the pressure chamber in sequence, and fix one end of the rubber membrane on the base of the pressure chamber with a rubber band to ensure that the rubber membrane does not leak water or air. Place the split half tube A and the split half tube B on both sides of the pressure chamber base, and carry out docking assembly. Put the ring body (4) on the middle part of the cylinder of the double valve, tighten the connecting bolt (5), and tighten the double valve. Connect the rubber suction conduit (2) connected to the suction hole with the vacuum pump for pumping, so that the rubber film is close to the inner wall of the split cylinder.

Step 2: Fill the soil sample. Inject an appropriate amount of anaerobic water into the mold, fill the rubber membrane with boiled and cooled sand in water, and control the height of the sample through the scale line (3) on the double valve. Level the surface of the sample, put filter paper, permeable stone, sample cap in sequence, and tighten the rubber membrane.

Step 3: Remove the double valve. Apply a negative pressure of 10KPa to the inside of the sample to make the sample stand. Stop the vacuum pumping, remove the outer collar of the double valve cylinder, and then remove the double valve, and the sample preparation is completed.

The beneficial effects of the present invention are: the assembly of the sample device is convenient and fast, the sample preparation process is intuitive, the height of the sample preparation can be precisely controlled through the scale lines on the double valve, and the vacuum pumping ensures that the diameter of the sample remains consistent along the height, thereby making The compactness of the triaxial sample is relatively uniform, and more reliable geotechnical triaxial test data can be obtained.

Description of drawings

Fig. 1 is a schematic diagram of the structure of the split half tube A.

Fig. 2 is a schematic diagram of the structure of the split half tube B.

Fig. 3 is a schematic diagram of the bottom surface of the two-lobe mould.

Figure 4 is a schematic diagram of the scale line.

Fig. 5 is a schematic diagram of a vacuum suction hole and a rubber conduit.

Figure 6 is a schematic diagram of a collar.

In the figure: 1-vacuum pumping hole; 2-vacuum pumping conduit; 3-scale line; 4-collar body; 5-connecting bolts.

Detailed ways

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

The present invention is shown in Fig. 1 to Fig. 6, and this experimental device comprises two petal molds, collar, and two petal molds are axially divided into two parts that can be tightly combined: split half tube A and split half tube B; A collar that fits over the body of the split cylinder. The two-lobed mold is divided into upper, middle and bottom parts. The bottom is the part combined with the test instrument base, and its height should be consistent with the height of the instrument base. The middle part is the part that forms the sample, and its height should meet the requirement that the ratio of the height to diameter of the prepared sample is 2.0 to 2.5. The upper part is the part for placing and fixing the sample cap. In order to facilitate the fixing of the rubber membrane and the binding of the rubber bands, the inner diameters of the bottom and upper parts of the double valve are slightly larger than those of the middle part, and the outer diameters of the upper part and the middle part carry out a smooth transition.

The collar is made of stainless steel, with a thickness of 0.5mm, and tightens the two-lobed mold. There is a movable connecting bolt rod on it, which has the function of adjusting the tightness of the collar.

The preparation method of a geotechnical triaxial test sample provided by the invention can be used to precisely control the height of the sample and obtain relatively reliable geotechnical triaxial test data from individuals. It mainly includes the following four steps:

Step 1: Assemble the double valve. First put permeable stones and filter paper on the base of the pressure chamber in sequence, and fix one end of the rubber membrane on the base of the pressure chamber with a rubber band to ensure that the rubber membrane does not leak water or air. Place the split half tube A and the split half tube B on both sides of the pressure chamber base, and carry out docking assembly. Put the ring body (4) on the middle part of the cylinder of the double valve, tighten the connecting bolt (5), and tighten the double valve. Connect the rubber suction conduit (2) connected to the suction hole with the vacuum pump for pumping, so that the rubber film is close to the inner wall of the split cylinder.

Step 2: Fill the soil sample. Inject an appropriate amount of anaerobic water into the mold, fill the rubber membrane with boiled and cooled sand in water, and control the height of the sample through the scale line (3) on the double valve. Level the surface of the sample, put filter paper, permeable stone, sample cap in sequence, and tighten the rubber membrane.

Step 3: Remove the double valve. Apply a negative pressure of 10KPa to the inside of the sample to make the sample stand. Stop the vacuum pumping, remove the outer collar of the double valve cylinder, and then remove the double valve, and the sample preparation is completed.

The samples prepared by the invention are relatively uniform and the preparation effect is good, so that more reliable triaxial test data can be obtained.

Claims (3)

1. A highly visualized geotechnical triaxial test sample device is characterized in that: the device includes two parts, a double valve and a collar, the double valve is used to control the sample, and the collar is used to adjust the compactness of the sample, and the sleeve The ring is set on the outer surface of the double valve; the double valve is axially divided into two parts that can be tightly combined: the split half tube A and the split half tube B; the double valve is made of tempered glass; the double valve is divided into upper part, middle part, There are three parts at the bottom; the bottom of the double valve is the part where the double valve is combined with the base of the test instrument, and its height is consistent with the height of the instrument base; the middle part of the double valve is the part that forms the sample, and the height of the middle part of the double valve meets the height and diameter of the prepared sample The ratio is 2.0 to 2.5; the upper part of the double valve is the part where the sample cap is placed and fixed; in order to facilitate the fixing of the rubber membrane and the binding of the rubber band, the inner diameter of the bottom and upper part of the double valve is larger than the inner diameter of the middle part, and the upper part and the middle part The outer diameters are joined by a smooth transition; There are scales on the double valves and they are symmetrical to each other; the half-tube A and the half-tube B are assembled to form a connecting seam, the scale is perpendicular to the connecting seam, and the two sides of the half-tube A and the half-tube B are respectively set with Scale line (3); the zero point of the scale line (3) is located on the top of the permeable stone on the base of the pressure chamber, and its minimum value is 1mm; In the middle of the double valve, a vacuum suction hole (1) made of tempered glass is arranged in the middle of the split half tube A and connected to a rubber suction catheter (2), so that the rubber membrane covers and clings to the inner surface of the double valve. 2. A highly visualized geotechnical triaxial test sample device according to claim 1, characterized in that: the collar is made of stainless steel, and the collar includes a collar body (4), a connecting bolt rod, and a connecting bolt (5); the ring body (4) is provided with a connecting bolt rod and a connecting bolt (5), and the locking degree of the connecting bolt rod is realized by adjusting the connecting bolt (5). 3. A highly visualized geotechnical triaxial test sample preparation method, characterized in that: the preparation method comprises the following steps: step 1: assembling double valves; step 2: filling soil samples; step 3: removing double valves; specifically , the step includes the following detailed steps, Step 1: Assemble the double valve; first place permeable stones and filter paper on the base of the pressure chamber in sequence, and fix one end of the rubber membrane on the base of the pressure chamber with a rubber band to ensure that the rubber membrane does not leak water or air; Place the split half tube B on both sides of the base of the pressure chamber, and carry out docking assembly; put the ring body (4) in the middle of the cylinder of the double valve, tighten the connecting bolt (5), and tighten the double valve; The rubber air suction conduit (2) of the air hole is connected with the vacuum pump for air extraction, so that the rubber film is close to the inner wall of the open cylinder; Step 2: Fill the soil sample; inject an appropriate amount of anaerobic water into the mold, fill the sand after boiling and cooling in the water into the rubber film, and control the height of the sample through the scale line (3) on the double valve; leveling test On the surface of the sample, put filter paper, permeable stone, sample cap in turn, and tighten the rubber film; Step 3: Remove the double valve; apply a negative pressure of 10KPa to the inside of the sample to make the sample stand; stop the vacuum pumping, remove the outer collar of the double valve cylinder, and then remove the double valve, and the sample preparation is completed.