CN112946244A

CN112946244A - Device for measuring plastic limit by using rubbing and rolling method in geotechnical test and using method

Info

Publication number: CN112946244A
Application number: CN202110262252.1A
Authority: CN
Inventors: 田丽霞; 周黎月; 李蕾; 余道洋; 杭荟旻
Original assignee: Shanghai Municipal Engineering Design Insitute Group Co Ltd
Current assignee: Shanghai Municipal Engineering Design Insitute Group Co Ltd
Priority date: 2021-03-10
Filing date: 2021-03-10
Publication date: 2021-06-11

Abstract

The invention discloses a test device for determining plastic limit by a rubbing and rolling method for geotechnical tests, which comprises a chassis and is characterized in that a ground glass plate and a control panel are arranged on the chassis, a heating resistance wire is arranged in the chassis below the ground glass plate, a measuring groove is carved on the upper end of the surface of the ground glass plate, a drying plate is embedded in the control panel, a drying resistance wire is arranged in the chassis below the drying plate, and a sponge groove is also arranged on the control panel and used for placing wet sponge. A heating resistance wire is arranged in a bottom disc below the ground glass plate, the ground glass plate can be heated to the temperature of the palm of a human body, when the ground glass plate is used for rolling the soil strips, the volatilization of water in the soil strips is accelerated, the rolling time is reduced, and the requirement of plastic limit water content is quickly met; the upper end of the surface of the ground glass plate is provided with the measuring groove, so that soil strips can be placed in the measuring groove at any time to determine whether the diameter of the soil strips meets the requirement, and the accuracy of the test result can be effectively improved. The test device is novel and unique, has a clear structure, is convenient to operate, saves time and labor, and has good innovation and practicability.

Description

Device for measuring plastic limit by using rubbing and rolling method in geotechnical test and using method

Technical Field

The invention relates to the field of geotechnical engineering investigation and geotechnical testing, in particular to a test device for determining plastic limit by a rubbing and rolling method in geotechnical testing and a using method thereof.

Technical Field

In geotechnical engineering investigation geotechnical test, limit water content of a soil sample needs to be measured, wherein plastic limit is one of main indexes of the limit water content, and related parameters such as plastic index and liquidity index of foundation soil can be obtained together with liquid limit. At present, the most common method for determining the plastic limit is a rubbing and rolling method, namely, a proper amount of representative soil sample is taken and kneaded to be non-sticky, or heating equipment such as a blower is used for blowing the soil sample to be non-sticky, then a proper amount of soil sample is taken and kneaded to be olive-shaped, the palm is used for rubbing and rolling back and forth on a ground glass plate, when the soil strip is rubbed to be 3mm, a crack is generated and begins to break, which indicates that the soil strip of the sample reaches the plastic limit, and boxing and drying can be carried out to determine the water content; when no crack is generated on the soil strip, the humidity of the soil sample is over-wet, and the soil sample needs to be dried and then is rubbed and rolled; when the soil strips are not rubbed to 3mm, the soil strips are broken, which indicates that the soil sample has low humidity and needs to be supplemented with water and then rubbed and rolled. The traditional rubbing and rolling method has the following defects that 1, the diameter of the rolled soil strips needs to be rubbed to 3mm, testers often visually measure whether the diameter of the soil strips meets the requirement by feeling, the diameter of the soil strips cannot be strictly controlled, and the accuracy of the test is influenced; 2. in the preparation process of the undisturbed sample, the undisturbed sample is dry or wet, the difference between the water content and the plastic limit water content is large, and the sample needs to be pretreated. If the water content of the sample is far larger than the plastic limit, air drying or auxiliary heating by a blower and the like is needed to enable the water content of the sample to be close to the plastic limit; if the water content of the sample is less than the plastic limit, water needs to be added to adjust the sample to be close to the plastic limit state, and the pretreatment stage of the process wastes time and labor; 3. the rubbing and rolling method adopts a palm to rub and roll on a ground glass plate, and due to the fact that a large temperature difference exists between the temperature of the palm and the ground glass plate, the upper temperature and the lower temperature of soil strips in the rubbing and rolling are inconsistent, volatile moisture is also uneven, and the efficiency and the quality of the rubbing and rolling are finally affected.

In conclusion, the test method for determining the plastic limit by the rolling method in the traditional geotechnical test is time-consuming and labor-consuming, the diameter error of the soil strips manually observed is large, the test quality is difficult to control, and in addition, the temperature and the humidity of the soil strips in the rolling process are not uniform due to the temperature difference between the palm temperature and the ground glass plate, so that the rolling efficiency and the rolling quality are influenced. The device is invented for improving the accuracy of plastic limit determination by a rubbing and rolling method, improving the working efficiency and saving the labor cost.

Disclosure of Invention

The invention aims to provide a test device for measuring the plastic limit by a rubbing and rolling method in a soil test, aiming at the defects in the measurement of the plastic limit by the traditional rubbing and rolling method.

In order to achieve the purpose, the technical scheme is that the test device for measuring the plastic limit by the geotechnical test rubbing and rolling method comprises a chassis and is characterized in that a ground glass plate and a control panel are arranged on the chassis, a heating resistance wire is arranged in the chassis below the ground glass plate, a measuring groove is carved in the upper end of the surface of the ground glass plate, a drying plate is embedded in the control panel, a drying resistance wire is arranged in the chassis below the drying plate, and a sponge groove is formed in the control panel and used for placing wet sponge.

Further, control panel is provided with stoving temperature controller and heating temperature controller, is used for controlling the heating resistor silk of adjusting ground glass board below and the stoving resistance silk of stoving board below respectively, through the temperature that sets up that shows on the temperature controller, and steerable resistance silk heats stoving board and ground glass board to reach experimental required temperature, promote experimental soil sample and soil strip moisture to volatilize fast, reduce the time of rolling by rubbing with the hands, improve test efficiency.

Furthermore, a ground glass plate is embedded on the right side of the chassis, a control panel is arranged on the left side of the chassis, 3 heating resistance wires are arranged in the chassis below the ground glass plate, and 3 measuring grooves with the diameter of 3mm are carved on the upper end of the surface of the ground glass plate; 3 drying resistance wires are arranged in a chassis at the lower part of the drying plate.

Furthermore, the drying plate is made of aluminum materials, so that heat can be transferred conveniently to quickly reach the required temperature.

The use method of the test device for determining the plastic limit by the geotechnical test rubbing and rolling method is characterized by comprising the following steps: switching on a power supply, placing wet sponge in the sponge groove, and heating the ground glass plate and the drying plate through the heating resistance wire and the drying resistance wire; when the required temperature is reached, taking a proper amount of soil sample for kneading, if the sample is sticky to hands during kneading, indicating that the water content is far larger than the plastic limit water content, placing the sample on a drying plate, heating the sample to quickly volatilize water, and when the sample is not sticky to hands, meeting the test requirement; if the sample is too dry or too hard during kneading, which indicates that the water content of the sample is far less than the plastic limit water content, the sample is placed on a wet sponge to dip a proper amount of water, the humidity of the sample is increased, and when the sample is softened and kneaded to be not sticky, the test requirement can be met; kneading a soil sample which is not sticky to hands into an olive shape, rolling and rubbing the soil sample on a ground glass plate back and forth, when the soil item is measured to be close to 3mm and a crack is generated to start to break, indicating that the water content of the soil strip is about to reach the plastic limit, quickly putting the rubbed soil strip into a measuring groove, and if the soil strip is just placed in the measuring groove, indicating that the humidity of the soil strip reaches the plastic limit, meeting the requirements, and quickly boxing and weighing; if the soil strips are placed in the measuring groove, the diameter is smaller, the humidity of the soil strips is lower, and the soil strips do not meet the test requirements, the soil samples need to be humidified, at the moment, a proper amount of soil samples are taken and placed in wet sponges to be dipped with a proper amount of water, the humidity of the soil samples is increased, and the soil samples are rolled on a ground glass plate after being kneaded again until the soil samples meet the requirements; if the soil strips are placed in the measuring groove, the diameter is larger, the humidity of the soil strips is higher, and the soil strips do not meet the test requirements, the soil samples need to be dried, at the moment, a proper amount of soil samples are taken and placed on a drying plate for heating and drying, the moisture of the soil samples is reduced, and the soil samples are rolled on a ground glass plate after being kneaded again until the soil samples meet the requirements.

A heating resistance wire is arranged in a bottom disc below the ground glass plate, the ground glass plate can be heated to the temperature of the palm of a human body, when the ground glass plate is used for rolling the soil strips, the volatilization of water in the soil strips is accelerated, the rolling time is reduced, and the requirement of plastic limit water content is quickly met; the upper end of the surface of the ground glass plate is provided with the measuring groove, so that soil strips can be placed in the measuring groove at any time to determine whether the diameter of the soil strips meets the requirement, and the accuracy of the test result can be effectively improved. A drying resistance wire is arranged in a chassis at the lower part of the drying plate, and a certain temperature can be set to heat the drying plate. In the test, if the soil sample is too wet, the soil sample can be flatly laid on a drying plate in advance, the temperature of the drying plate is adjusted, the sample is quickly heated to evaporate water, and the soil sample can be in a rolling and rubbing state as soon as possible so as to shorten the rubbing and rolling time. Control panel is provided with the sponge groove for place wet sponge, and is on the low side or comparatively dry harder when soil sample humidity, and is less than when moulding limit moisture content, or in the experiment soil strip does not rub to and just produce the crack fracture when 3mm, show that soil sample humidity is less than when moulding limit moisture content, need increase soil sample moisture. At the moment, the soil sample can be taken and dipped with a proper amount of water in the wet sponge, the humidity of the soil sample is increased, and the soil sample continues to be rubbed and rolled to reach the required humidity. The invention has the advantages of novel and unique test device, clear structure, convenient operation, time and labor saving, and good innovation and practicability.

Drawings

FIG. 1 is a front view of a test apparatus and method of use for determining plastic limit in a soil test using a rubbing and rolling method;

figure 2-a perspective view of a test apparatus and method of use for determining the plastic limit in a roll-to-roll method of soil testing.

The figure includes: 1-a ground glass plate; 2-measuring the groove; 3-drying the plate; 4-a control panel; 5-wet sponge; 6-drying the temperature controller; 7-heating the temperature controller; 8-a chassis; 9-drying the resistance wire; 10-heating resistance wire.

Detailed Description

The invention is described in detail below with reference to the figures and the specific examples of its implementation.

As shown in fig. 1 and 2, the schematic diagram of the device of the invention is shown, when the device is used, firstly, a power supply is switched on, a wet sponge 5 is placed, a heating temperature controller 7 and a drying temperature controller 6 are sequentially switched on to set to proper temperature, a ground glass plate 1 and a drying plate 3 are heated through a heating resistance wire 10 and a drying resistance wire 9, when the required temperature is reached, a proper amount of soil sample is kneaded, if the sample is sticky to the hand during kneading, which indicates that the moisture content is far greater than the plastic limit moisture content, the humidity of the sample needs to be reduced, the sample is placed on the drying plate 3, so that the sample is heated to rapidly volatilize moisture, and when the sample is not sticky to the hand, the test requirement can be met; if the sample is found to be too dry or too hard during kneading, the moisture content of the sample is far less than the moisture content of the plastic limit, the sample can be placed on a wet sponge 5 to dip in a proper amount of moisture, the humidity of the sample is increased, and when the sample is softened and kneaded to be not sticky, the test requirement can be met. Kneading a soil sample which is not sticky to hands into an olive shape, rolling and rubbing the soil sample on a ground glass plate 1 back and forth, when the soil item is measured to be close to 3mm and a crack is generated to start to break, indicating that the water content of the soil strip is about to reach the plastic limit, quickly putting the rubbed soil strip into a measuring groove 2, and if the soil strip is just placed in the measuring groove 2, indicating that the humidity of the soil strip reaches the plastic limit, meeting the requirements, and quickly boxing and weighing; if the soil strips are placed in the measuring groove 2, the diameter of the soil strips is smaller, which indicates that the humidity of the soil strips is lower and does not meet the test requirements, the soil samples need to be humidified, at the moment, a proper amount of soil samples are taken and placed in the wet sponge 5 to be dipped with a proper amount of water, the humidity of the soil samples is increased, and the soil samples are rolled on the ground glass plate 1 after being kneaded again until the soil samples meet the requirements; if the soil strips are placed in the measuring groove 2, the diameter of the soil strips is larger, the humidity of the soil strips is higher, and the soil strips do not meet the test requirements, the soil samples need to be dried, at the moment, a proper amount of soil samples are taken and placed on the drying plate 3 for heating and drying, the moisture of the soil samples is reduced, and the soil samples are rolled on the ground glass plate 1 after being kneaded again until the soil samples meet the requirements.

Claims

1. A test device for determining plastic limit by a rubbing and rolling method for geotechnical tests comprises a chassis and is characterized in that a ground glass plate and a control panel are arranged on the chassis, a heating resistance wire is arranged in the chassis below the ground glass plate, a measuring groove is carved in the upper end of the surface of the ground glass plate, a drying plate is embedded in the control panel, a drying resistance wire is arranged in the chassis below the drying plate, and a sponge groove is further formed in the control panel and used for placing wet sponge.

2. The test device for testing the plastic limit by the geotechnical test rubbing and rolling method according to claim 1, wherein the control panel is provided with a drying temperature controller and a heating temperature controller for controlling and adjusting the heating resistance wire below the ground glass plate and the drying resistance wire below the drying plate respectively.

3. The test device for testing the plastic limit by the geotechnical test rubbing and rolling method according to claim 1, wherein the ground glass plate is embedded on the right side of the chassis, the control panel is arranged on the left side of the chassis, 3 heating resistance wires are arranged in the chassis below the ground glass plate, and 3 measuring grooves with the diameter of 3mm are carved on the upper end of the surface of the ground glass plate; 3 drying resistance wires are arranged in a chassis at the lower part of the drying plate.

4. The test device for the plastic limit measurement by the soil test rolling method according to claim 1, wherein the drying plate is made of aluminum material.

5. The use method of the test device for determining the plastic limit by the geotechnical test rubbing and rolling method is characterized by comprising the following steps: switching on a power supply, placing wet sponge in the sponge groove, and heating the ground glass plate and the drying plate through the heating resistance wire and the drying resistance wire; when the required temperature is reached, taking a proper amount of soil sample for kneading, if the sample is sticky to hands during kneading, indicating that the water content is far larger than the plastic limit water content, placing the sample on a drying plate, heating the sample to quickly volatilize water, and when the sample is not sticky to hands, meeting the test requirement; if the sample is too dry or too hard during kneading, which indicates that the water content of the sample is far less than the plastic limit water content, the sample is placed on a wet sponge to dip a proper amount of water, the humidity of the sample is increased, and when the sample is softened and kneaded to be not sticky, the test requirement can be met; kneading a soil sample which is not sticky to hands into an olive shape, rolling and rubbing the soil sample on a ground glass plate back and forth, when the soil item is measured to be close to 3mm and a crack is generated to start to break, indicating that the water content of the soil strip is about to reach the plastic limit, quickly putting the rubbed soil strip into a measuring groove, and if the soil strip is just placed in the measuring groove, indicating that the humidity of the soil strip reaches the plastic limit, meeting the requirements, and quickly boxing and weighing; if the soil strips are placed in the measuring groove, the diameter is smaller, the humidity of the soil strips is lower, and the soil strips do not meet the test requirements, the soil samples need to be humidified, at the moment, a proper amount of soil samples are taken and placed in wet sponges to be dipped with a proper amount of water, the humidity of the soil samples is increased, and the soil samples are rolled on a ground glass plate after being kneaded again until the soil samples meet the requirements; if the soil strips are placed in the measuring groove, the diameter is larger, the humidity of the soil strips is higher, and the soil strips do not meet the test requirements, the soil samples need to be dried, at the moment, a proper amount of soil samples are taken and placed on a drying plate for heating and drying, the moisture of the soil samples is reduced, and the soil samples are rolled on a ground glass plate after being kneaded again until the soil samples meet the requirements.