CN201974353U - Online pressure gradient soil granulometer - Google Patents

Abstract

The utility model belongs to soil particle analysis instruments, in particular to an online differential pressure soil particle size analyzer. The on-line differential pressure soil particle size analyzer includes a special measuring barrel containing the suspension of soil particles to be tested. A micro-probe pressure sensor is installed inside the special measuring barrel at a certain depth. The micro-probe pressure sensor passes through the special measuring barrel. The external signal line is connected to a photoelectric isolator, and the photoelectric isolator is connected to the microcomputer system; the microcomputer system obtains the soil pressure through data processing and analysis according to the change value of the static pressure of the soil particle suspension detected by the pressure sensor. The particle size and gradation of the particles are displayed and printed. The utility model has mature technology and reliable principle; the test operation is simple, and the online detection method is adopted, so that there is no human factor in the test process, and the measurement accuracy and sensitivity are high; the measured soil particle size range can be less than 0.075mm.

Description

An online differential pressure soil particle size analyzer

technical field

The utility model belongs to soil particle analysis instruments, in particular to an online differential pressure soil particle size analyzer.

Background technique

The composition of soil includes three aspects: particle size composition, mineral composition and chemical composition. Soil in nature, as the soil particles that make up the soil skeleton, has different sizes and properties. In engineering, the relationship between the various sizes of particles that make up the soil is often referred to as the particle size composition of the soil. The particle size composition of soil has a decisive influence on a series of engineering properties of soil, so it is one of the important contents of engineering properties research. In order to facilitate the study of the size of soil particles, the particle size section is usually divided according to the diameter of soil particles (abbreviated as particle size, in mm). The particles with similar size ratios and basically the same engineering properties included in each section are combined into groups, called particle groups. Generally, natural soil is composed of several granule groups, and the proportion of each granule group in the total mass of the soil is called particle size composition, also known as particle gradation. The test of determining the percentage of each particle group in the total mass in the soil by a specified method is called the particle analysis of soil.

At present, the commonly used soil particle size analysis methods at home and abroad mainly include sieving method, sedimentation method, ultrasonic measurement method, laser method and so on. Among them, the sieving method is difficult to measure particles with a particle size of less than 0.075mm. The sedimentation method includes the pipette method, the sedimentation balance method, and the specific gravity balance method. Although they are widely used, not only the measurement time is long, but the measurement results are often Depending on the technical level of the operator, online real-time control of the measurement cannot be realized. The ultrasonic measurement method and laser diffraction method also have high requirements on the working environment and sensors, and the probe device needs to be calibrated frequently, which brings difficulties to maintenance and other problems. In order to overcome the above problems, the differential pressure soil particle size analysis method can be used. At present, there is no instrument for the differential pressure analysis of the soil particle size.

Contents of the invention

The purpose of this utility model is to provide an online differential pressure soil particle size analyzer with simple operation, high measurement accuracy and sensitivity for the above-mentioned defects in the prior art.

The utility model achieves the above-mentioned purpose through the following technical scheme: the online differential pressure soil particle size analyzer includes a special measuring bucket for holding the suspension of soil particles to be tested, and the inside of the special measuring bucket at a certain depth A micro-probe pressure sensor is installed, and the micro-probe pressure sensor is connected to a photoelectric isolator through a signal line outside the special measuring barrel, and the photoelectric isolator is connected to the microcomputer system; The change value of the static pressure of the particle suspension, the particle size and gradation of the soil particles can be obtained through data processing and analysis, and displayed and printed.

More specifically, the height of the special measuring barrel is 800mm, and the inner diameter is 120mm; the pressure sensor is installed on the inner side 400mm away from the bottom of the barrel.

The working process and principle of the utility model are as follows: put a certain quality of air-dried tested soil particles into a special measuring bucket, inject distilled water and stir fully to make a suspension with a uniform concentration, add a dispersant, and then use the The pressure sensor in the barrel detects the relationship of the static pressure of the suspension at this place with time, and the magnitude of the static pressure is proportional to the weighted density value of the suspension above the place, so the weighted density value of the suspension above the place changes with time. The pressure signal is sent to the microcomputer system through the photoelectric isolator for data processing and analysis, and the data of soil particle size and gradation are obtained, which are displayed and printed on the screen.

The utility model has mature technology and reliable principle; the test operation is simple, the on-line detection method is adopted, the test process has no artificial factors, and the measurement accuracy and sensitivity are high. The range of soil particle size measured by the utility model can be less than 0.075mm, and the test time of each soil sample is 12 hours, and the calibration and detection of the instrument can be carried out at room temperature, so it has good promotion and use value.

Description of drawings

Fig. 1 is the structural representation of the utility model embodiment.

Detailed ways

Below in conjunction with accompanying drawing and embodiment the utility model is described in further detail.

Referring to Fig. 1, in the present embodiment, the height of the special-purpose measuring bucket 1 that holds the soil particle suspension to be tested is 800mm, and the inner diameter is 120mm; The inboard distance bucket bottom 400mm of special-purpose measuring bucket 1 is equipped with high precision and sensitivity The microprobe pressure sensor 2 is connected to the photoelectric isolator 3 through the signal line 5 outside the special measuring barrel, and the photoelectric isolator 3 is connected to the microcomputer system 4.

The differential pressure soil particle size analyzer must be calibrated in advance. Then put the sieved air-dried soil sample into the special measuring bucket 1, inject distilled water and an appropriate amount of dispersant and stir to make a suspension with uniform concentration, and the dispersant is hexametaphosphoric acid solution. Turn on the switch of the analyzer and start to detect the change of the static pressure of the suspension at the pressure sensor 2 in the special measuring bucket 1. During the settling process, it is detected that the static pressure of the suspension at the pressure sensor 2 gradually decreases. The pressure sensor 2 converts the pressure value into a 4~20mA current signal, sends it to the photoelectric isolator 3 through the signal line 5 to eliminate various interference and noise, and then sends it to the microcomputer system 4 for analysis and processing to convert it into a weighted density value of the suspension , so that the analyzer can record the change of the weighted density ρ of the above suspension with time t, and draw the measurement results as a ρ-t diagram. According to the Stokes principle and the standard of geotechnical test methods (GBT50123-1999), the microcomputer system 4 analyzes and processes the data to obtain the particle size and gradation of the soil particles, and display and print on the screen.

The particle size range of the soil particles measured by the utility model is less than 0.075mm, and the test time of each soil sample is 12 hours, and the instrument calibration and detection are all carried out at room temperature.

Claims (2)

1. An on-line differential pressure type soil particle size analyzer is characterized in that: it comprises a special-purpose measuring barrel for holding the suspension of soil particles to be measured, and a micro-probe pressure sensor is installed inside a certain degree of depth of the special-purpose measuring barrel. The micro-probe pressure sensor is connected to a photoelectric isolator through a signal line outside the special measuring barrel, and the photoelectric isolator is connected to the microcomputer system; the microcomputer system passes The particle size and gradation of soil particles are obtained through data processing and analysis, and displayed and printed out. 2. The online differential pressure soil particle size analyzer according to claim 1, characterized in that: the height of the special measuring barrel is 800 mm, and the inner diameter is 120 mm; the pressure sensor is installed on the inner side of the 400 mm away from the bottom of the barrel.

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