CN106840990B

CN106840990B - Osmotic device capable of realizing variable water pressure effect

Info

Publication number: CN106840990B
Application number: CN201611041567.9A
Authority: CN
Inventors: 王胤; 任玉宾; 杨庆
Original assignee: Dalian University of Technology
Current assignee: Dalian University of Technology
Priority date: 2016-11-21
Filing date: 2016-11-21
Publication date: 2023-07-14
Anticipated expiration: 2036-11-21
Also published as: CN106840990A

Abstract

The invention discloses a penetration device capable of realizing variable water pressure action, and belongs to the technical field of civil engineering. The penetrating device comprises a variable-frequency circulating water supply system and a test measurement system, the variable-frequency water pressure is provided by a water pump controlled by a PLC control cabinet and a frequency converter, and the circulating water supply function is realized by a water pipe, a tee joint and a ball valve. The test measurement system comprises a test section, a differential pressure transmitter, a flowmeter, a signal converter, a computer and the like, wherein a pressure taking point of the test device is positioned at an axis position and is designed into a sphere with a hole, and the differential pressure transmitter, the flowmeter, the signal converter and the computer are mutually connected and are used for automatically collecting water pressure difference and water flow. The invention realizes variable water pressure, adopts the differential pressure transmitter to automatically measure the water pressure difference, can ensure higher measurement precision and wider measurement range, overcomes the defects of larger error, water resource waste and the like of the traditional osmosis device, and has convenient and quick test process and reliable result.

Description

Osmotic device capable of realizing variable water pressure effect

Technical Field

The invention belongs to the technical field of civil engineering, and relates to a test device for researching the permeability characteristics of a porous medium under the action of variable water pressure.

Background

Porous media are widely available in nature and are solid polymers with rich pores. The permeability is an important physical and mechanical property of the porous medium, and refers to the property of the porous medium allowing fluid to flow through interconnected micro pores, the permeability coefficient represents the strength of the permeability of the porous medium, the calculation method is based on Darcy's law of seepage, namely that the seepage speed and the hydraulic gradient are in direct proportion v=ki, and the proportionality coefficient k is the permeability coefficient.

The osmotic coefficient of porous media is measured by an indoor experimental method, and a traditional osmotic device in civil engineering is mainly a constant head osmotic instrument such as TST-70 type. The penetrometer of the type can only meet the requirements of general engineering, but can not study the permeability of porous media when the variable hydraulic pressure acts on under dynamic load conditions such as waves, earthquakes and the like, meanwhile, the traditional penetrometer relies on manual measurement and reading of data, so that the test error is large, and the test process is time-consuming and labor-consuming. Therefore, aiming at the defects of the traditional penetrometer, a novel test device capable of researching the permeation characteristics of the porous medium under the action of variable water pressure is invented.

Disclosure of Invention

Aiming at the defects of the traditional osmosis device, the invention controls the water pump to provide periodically-changed water pressure through the PLC control cabinet and the frequency converter, adopts the water pipe, the tee joint and the ball valve to form a circulating water supply system, improves the design of a pressure point of a test section to more accurately measure the water pressure difference value of the section of a sample, and adopts the data acquisition system consisting of a differential pressure transmitter, a flowmeter, a signal converter and a computer to automatically measure and record the water pressure difference value and the water flow.

The technical scheme of the invention is as follows:

a penetration device capable of realizing the function of variable water pressure comprises a variable frequency circulating water supply system I and a test measurement system II;

the variable-frequency circulating water supply system I comprises a water tank 1, a water pump 2, a frequency converter 3, a PLC control cabinet 4, a ball valve 5, a water pipe and a tee joint, wherein the water tank 1, the water pump 2, the frequency converter 3 and the PLC control cabinet 4 are sequentially connected, the water tank 1 is used as a container for storing a water source, the water pump 2 provides power for circulating water, the frequency converter 3 and the PLC control cabinet 4 periodically change through control voltage, so that the rotation speed of an impeller of the water pump 2 periodically changes, and the water pressure of a water outlet of the water pump 2 periodically changes; the water outlet of the water pump 2 is connected with a water pipe, the water pipe is connected with a tee joint, one end of the tee joint is directly connected with a test device through the water pipe, and a first ball valve 5-1 and a flowmeter 7 are arranged on the water pipe; the other end of the tee joint is connected with the water tank 1 through a water pipe, and a second ball valve 5-2 is arranged on the water pipe; the water outlet of the test device flows back to the water tank 1 through a water pipe, and all the joints adopt a clamp and a raw rubber belt for leakage-proof treatment;

the test measurement system II comprises a test device, a differential pressure transmitter 6, a flowmeter 7, a signal converter 13 and a computer 14, wherein the main body of the test device is of a cylindrical structure made of organic glass, and the two ends of the test device are respectively provided with a left cover plate 15 and a right cover plate 20; the inside of the test device is divided into a left buffer section 16, a middle sample loading section 18 and a right buffer section 19 through two water permeable pore plates 17, a filter screen is stuck on one side of the water permeable pore plates 17, which is close to the sample loading section 18, and water rubber rings are connected through flanges; the left buffer section 16 and the right buffer section 19 are respectively provided with an exhaust hole 8, the exhaust holes 8 are connected with an exhaust pipe 11, and the exhaust pipe 11 is provided with a water stop clamp 10; the two ends of the sample loading section 18 are provided with pressure sampling points 9, the pressure sampling points 9 are in a sphere shape with tiny holes, and the pressure sampling points 9 are positioned at the axial line of the sample loading section 18 and are connected with the differential pressure transmitter 6 through the outer pressure guide pipe 12; differential pressure transmitter 6 and flowmeter 7 are connected to signal transducer 13, and signal transducer 13 is connected to computer 14.

The invention has the beneficial effects that: the device can realize the research of the permeability characteristics of the porous medium under the action of variable hydraulic pressure under dynamic load conditions such as sea waves, earthquakes and the like. The circulating water supply system can save water resources, the pressure sampling point is arranged in the middle of the sample, a more accurate pressure value can be obtained, the differential pressure transmitter can automatically measure the water pressure difference value, higher measurement precision and wider measurement range can be ensured, particularly, the measuring time can be greatly shortened for low-permeability materials such as rocks and silt by combining a variable-frequency pulse measuring method, the water flow can be automatically measured by the flowmeter, the instantaneous water pressure difference value and the water flow under the action of variable water pressure can be automatically acquired by the computer data acquisition system, and the defects that the traditional osmosis device increases test errors and wastes water resources by means of manual measurement and reading of data are overcome. The invention has the advantages of convenient and quick test process and reliable test result, and has multiple purposes of education and teaching, construction guidance, scientific research and the like.

Drawings

Fig. 1 is a schematic diagram of the system architecture of the present invention.

FIG. 2 is a cross-sectional view of the test apparatus of the present invention.

In the figure: i, a variable-frequency circulating water supply system; II, testing a measuring system; 1, a water tank; 2, a water pump; 3, a frequency converter; 4 a PLC control cabinet; 5-1 a first ball valve; 5-2 a second ball valve; a differential pressure transmitter; a flow meter 7; 8, an exhaust hole; 9, taking a pressure point; 10, a water stop clamp; 11 an exhaust pipe; 12 impulse pipes; 13 a signal converter; 14, a computer; 15 left cover plate; 16 left buffer segments; 17 water permeable orifice plate; 18, loading sample sections; 19 right buffer segment; 20 right cover plate.

Detailed Description

The following describes the embodiments of the present invention in detail with reference to the technical scheme and the accompanying drawings.

Examples

First, the variable frequency circulating water supply system I and the test measurement system II are assembled, inspected and tested. Distilled water is injected into the water tank 1, the first ball valve 5-1 is fully closed, the second ball valve 5-2 is fully opened, and the power supply of the water pump 2 is connected to check whether the water pump works normally. The first ball valve 5-1 is opened slowly, so that water slowly enters the test device, the water stop clamp 10 is opened to remove air in the test device, after the water flow in the test device is stable, air bubbles in the differential pressure transmitter 6 and the flowmeter 7 are removed, water is continuously introduced for a period of time, and water leakage points are checked and removed. The power supply of the differential pressure transmitter 6 and the flowmeter 7 is connected, and whether the data acquisition system 13 and the computer 14 work normally or not is checked. After each work inspection is completed, the power supply of the water pump 2, the differential pressure transmitter 6 and the flowmeter 7 is cut off, and the water in the test device is discharged.

Then, preliminary preparation work for the test is performed. The frequency of the frequency converter 3 is controlled by the PLC control cabinet 4 to realize periodic change, and the differential pressure transmitter 6 and the flowmeter 7 are checked and calibrated. The test device is disassembled, gravel is filled in the left buffer section 16 and the right buffer section 19, and test materials are uniformly filled in the sample filling section 18, so that a porous medium with a certain porosity is formed. After the sample is loaded, the power supply of the water pump 2 is connected, the first ball valve 5-1 is opened, the sample is slowly saturated, and residual bubbles in the test device, the differential pressure transmitter 6 and the flowmeter 7 are removed.

Finally, test measurement work is performed. Providing variable water pressure according to the variable frequency condition set by the PLC control cabinet 4, adjusting the first ball valve 5-1 to a certain opening degree, and recording the differential pressure value acquired by the differential pressure transmitter 6 and the flow value acquired by the flowmeter 7 by a computer 14 after the water flow speed is stable; the opening degree of the first ball valve 5-1 and the second ball valve 5-2 is regulated to gradually increase the water flow speed, and the measuring process is repeated until the test is finished; and converting the flow into an instantaneous water flow speed u flowing through the section of the sample, dividing the water pressure difference by the length of the seepage path to obtain an instantaneous hydraulic gradient i, and obtaining a seepage relation curve of the porous medium under the action of the variable water pressure.

Claims

1. The osmosis device capable of realizing the variable water pressure effect is characterized by comprising a variable-frequency circulating water supply system (I) and a test measurement system (II);

the variable-frequency circulating water supply system (I) comprises a water tank (1), a water pump (2), a frequency converter (3), a PLC control cabinet (4), a ball valve (5), a water pipe and a tee joint, wherein the water tank (1), the water pump (2), the frequency converter (3) and the PLC control cabinet (4) are sequentially connected, the water tank (1) is used as a container for storing water sources, the water pump (2) provides power for circulating water, the frequency converter (3) and the PLC control cabinet (4) periodically change through control voltage, so that the rotating speed of an impeller of the water pump (2) periodically changes, and the water pressure of a water outlet of the water pump (2) periodically changes; the water outlet of the water pump (2) is connected with a water pipe, the water pipe is connected with a tee joint, one end of the tee joint is directly connected with the test device through the water pipe, and a first ball valve (5-1) and a flowmeter (7) are arranged on the water pipe; the other end of the tee joint is connected with a water tank (1) through a water pipe, and a second ball valve (5-2) is arranged on the water pipe; the water outlet of the test device flows back to the water tank (1) through a water pipe, and the joints adopt a clamp and a raw rubber belt for leakage-proof treatment;

the test measurement system (II) comprises a test device, a differential pressure transmitter (6), a flowmeter (7), a signal converter (13) and a computer (14), wherein the main body of the test device is of a cylindrical structure made of organic glass, and the two ends of the test device are respectively provided with a left cover plate (15) and a right cover plate (20); the inside of the test device is divided into a left buffer section (16), a sample loading section (18) and a right buffer section (19) through two permeable pore plates (17), a filter screen is stuck on one side, close to the sample loading section (18), of the permeable pore plates (17), and the two permeable pore plates are connected through a flange by utilizing a water-stopping rubber ring; the left buffer section (16) and the right buffer section (19) are respectively provided with an exhaust hole (8), the exhaust holes (8) are connected with an exhaust pipe (11), and the exhaust pipe (11) is provided with a water stop clamp (10); the two ends of the sample loading section (18) are provided with pressure sampling points (9), the pressure sampling points (9) are in a sphere shape with tiny holes, and the pressure sampling points (9) are positioned at the axial line position of the sample loading section (18) and are connected with the differential pressure transmitter (6) through an outer pressure guide pipe (12); the differential pressure transmitter (6) and the flowmeter (7) are connected with a signal converter (13), and the signal converter (13) is connected with a computer (14).