CN102680377A - Test device for measuring rising heights and speeds of porous medium capillary water - Google Patents

Abstract

A test device for measuring the rising height and rate of capillary water in porous media, characterized in that the device includes a water tank (1), a downpipe (2), a downpipe switch (3), a three-way joint (4), and a three-way switch (5), pressure measuring tube (6), overflow pipe (7), overflow pipe switch (8), capillary tube (9), lower permeable stone (10), coarse sand (11), upper permeable stone (12), drainage Tracheal switch (13), exhaust pipe (14), soil sampling hole plug (15), sample (16), sample cylinder (17), plastic pipe (18), water supply pipe (19), water supply pipe switch (20). The instrument used in this measurement method is simple to manufacture, high in measurement accuracy, easy to use, and meets the control requirements of the capillary water rise height of the sample. It can directly measure parameters such as the capillary water rise height and rate of various porous media including sand, sandy soil, and silt. Indoor or on-site testing of parameters such as the height and rate of capillary water rise in various porous media encountered in civil engineering.

Description

A test device for measuring the rising height and rate of capillary water in porous media

technical field

The invention relates to a geotechnical testing device, which belongs to the technical field of civil engineering (geotechnical) engineering.

Background technique

Capillarity in porous media is ubiquitous in nature, and its internal two-phase flow, whether for the media itself or multiphase flow systems, has a wide range of engineering application backgrounds. Capillarity in soil is due to the mutual attraction between soil particles and water molecules and the surface tension of water. The capillary water rising height test can be used to calculate the rising height and rising speed of the capillary water in the soil, which is used to estimate whether some areas will become swamps or salinization when the groundwater level rises, and whether the buildings are soaked. Possibilities and other issues, and can be used to calculate the necessary depth to lower the groundwater table. At present, there are many methods for measuring the rising height of capillary water, and each method is aimed at different types of porous media, and the standardized operation has not yet been realized. The application is to invent a test device suitable for the measurement of the rising height and rate of capillary water in various porous media.

Contents of the invention

The purpose of the present invention is to provide a capillary water rise height measuring device suitable for porous media, which solves the problem of measuring the capillary water rise height and rate in sandy soil or silt.

The technical solution of the present invention is characterized in that a test device for measuring the rising height and rate of capillary water in porous media includes a water tank 1, a sewer pipe 2, a sewer pipe switch 3, a three-way joint 4, a three-way switch 5, a pressure measuring Pipe 6, overflow pipe 7, overflow pipe switch 8, capillary tube 9, lower permeable stone 10, coarse sand 11, upper permeable stone 12, exhaust pipe switch 13, exhaust pipe 14, soil-taking hole plug 15, sample 16, Sample cylinder 17, plastic pipe 18, water supply pipe 19, water supply pipe switch 20. The water tank 1 is connected to the piezometric tube 6 through the sewer pipe 2, the piezometric tube 6 is connected to the capillary tube 9 through the plastic tube 18, the sewer pipe 2 is connected to the piezometric tube 6 through the replenishment pipe 19, and the replenishment pipe 19 is controlled by the replenishment pipe switch 20, The downpipe 2 is equipped with a downpipe switch 3, the tee joint 4 is equipped with a tee switch 5, the pressure measuring tube 6 is connected with an overflow pipe 7, the overflow pipe 7 is controlled by the overflow pipe switch 8, and the lower permeable stone 10 is covered with coarse sand 11 , the upper permeable stone 12 is installed on the coarse sand 11, the surface of the upper permeable stone 12 is covered with filter paper, the sample 16 is installed on the filter paper, the sample cylinder 17 is connected to the exhaust pipe 14, and the exhaust pipe 14 is controlled by the exhaust pipe switch 13 , the sample cylinder 17 is equipped with a plurality of soil-taking hole plugs 15, the thickness of the sample cylinder 17 is greater than 0.5cm, and the inner diameter is greater than 3-4cm. Value top, and flush with upper permeable stone 12 top surfaces.

Advantage of the present invention:

The instrument is simple to manufacture, has high measurement accuracy, and is easy to use. It meets the requirements for control of the capillary water rise height of the sample, and can directly measure parameters such as the capillary water rise height and rate of various porous media including sand, sandy soil, and silt.

Scope of application of the present invention;

It can be used for indoor or on-site testing of parameters such as the height and rate of capillary water rise and rate in various porous media encountered in civil engineering.

Description of drawings:

Fig. 1 is a schematic structural diagram of a test device for measuring the rising height and velocity of capillary water in porous media. Among them are: water tank 1, downpipe 2, downpipe switch 3, tee joint 4, tee switch 5, pressure measuring tube 6, overflow pipe 7, overflow pipe switch 8, capillary tube 9, lower permeable stone 10, coarse sand 11 , Upper permeable stone 12, exhaust pipe switch 13, exhaust pipe 14, soil-taking hole plug 15, sample 16, sample cylinder 17, plastic pipe 18, water supply pipe 19, water supply pipe switch 20.

Detailed ways:

Embodiment: utilize this device to measure the test method of porous medium capillary water rising height as follows:

(1) Test method for the rise height of capillary water in sandy soil:

① Put the lower permeable stone 10 into the sample tube 17, spread 1 cm thick coarse sand 11 on the lower permeable stone 10, install the upper permeable stone 12 on the coarse sand 11, and spread a layer of filter paper on the upper permeable stone 12;

②Take 1.5kg of air-dried sand, disperse it into the sample tube 17, and tamp it lightly with a tamping rod to reach the required dry density. flush;

③ Turn off the water pipe switch 3, the three-way switch 5 and the replenishment pipe switch 20, open the overflow pipe switch 8 and the exhaust pipe switch 13, and fill the water tank 1 with water;

④ Turn on the downpipe switch 3 to allow water to slowly flow into the piezometric tube 6 and capillary tube 9, and after the upper permeable stone 12 is soaked in water to exhaust, turn off the exhaust pipe switch 13;

⑤ After the water begins to soak the bottom of the sample 16 and the overflow pipe 7 begins to overflow, turn off the downpipe switch 3 and start timing. After 5, 10, 20, 30, and 60 minutes, record the rising height of the capillary water. According to the degree of capillary water rise and the depth of the sand color, record it every few hours to obtain the capillary water rise height, draw the capillary water rise height and time curve, and obtain the capillary water rise rate;

⑥ During the test, when there is no water dripping from the overflow pipe 7, turn on the water replenishment pipe switch 20 repeatedly and intermittently, inject water into the piezometric pipe 6, and turn off the water replenishment pipe switch 20 when there is water dripping from the overflow pipe 7;

⑦ After the test, open the soil-boring hole plug 15 of the sample cylinder 17 from top to bottom, scoop out an appropriate amount of sample 16 with a small spoon, conduct a moisture content test, and draw the curve of the moisture content of the sample 16 and the rising height of capillary water.

(2) Test method for the rise height of silt capillary water:

① Put the lower permeable stone 10 into the sample tube 17, spread 1 cm thick coarse sand 11 on the lower permeable stone 10, install the upper permeable stone 12 on the coarse sand 11, and spread a layer of filter paper on the upper permeable stone 12;

②Take 1.5 kg of air-dried silty soil, disperse it into the sample tube 17, tamp it lightly with a tamping stick, and after reaching the required dry density, seal the contact parts around the sample 16 with the sample tube 17 with paraffin wax. The 0-point scale value on the top of the pressure measuring tube should be flush with the lower surface of sample 16;

③ When using the original silt sample, first measure the water content and density of the sample, then cut the silt sample diameter to the size of the inner diameter of the sample cylinder 17, and the sample height is twice the diameter, and slowly put the sample into the sample cylinder 17 Finally, the contact portion between the periphery of the sample 16 and the sample cylinder 17 is sealed with paraffin. At this time, the scale value at 0 o'clock on the top of the pressure measuring tube should be flush with the lower surface of the sample 16;

④ Turn off the downpipe switch 3, the three-way switch 5, the replenishment pipe switch 20 and the overflow pipe switch 8 in turn, turn on the exhaust pipe switch 13, and fill the water tank 1 with water;

⑤ Turn on the downpipe switch 3 to allow water to slowly flow into the piezometric tube 6 and the capillary 9, and after the water soaks the upper permeable stone 12 to exhaust, close the exhaust pipe switch 13;

⑥ Slowly disconnect or turn off the water pipe switch 3, so that the water slowly flows from bottom to top to saturate the sample 16, and when the surface of the sample 16 sees water, turn off the water pipe switch 3;

⑦ Slowly turn on the three-way switch 5 to make the water level of the piezometric tube 6 drop slowly and gradually. When the water level in the tube stops falling or starts to rise, write down the scale value of the water surface in the piezometric tube 6 at this time, which is the test sample Capillary rise height of 16;

⑧Repeat ⑤-⑦, take the arithmetic mean value of the two measurement results, which is the capillary water rise height of the sample 16;

⑨ After the test, open the soil-taking hole plug 15 of the sample cylinder 17 from top to bottom, scoop out an appropriate amount of sample 16 with a small spoon, conduct a moisture content test, and draw the curve of the moisture content of the sample 16 and the rising height of capillary water.

Claims (1)

1. A test device for measuring the rising height and rate of capillary water in porous media is characterized in that the device includes a water tank (1), a downpipe (2), a downpipe switch (3), a tee joint (4), three Through switch (5), pressure measuring tube (6), overflow pipe (7), overflow pipe switch (8), capillary tube (9), lower permeable stone (10), coarse sand (11), upper permeable stone (12) , exhaust pipe switch (13), exhaust pipe (14), soil-borrowing hole plug (15), sample (16), sample cylinder (17), plastic pipe (18), water supply pipe (19), water supply The pipe switch (20), the water tank (1) is connected with the pressure measuring tube (6) through the water pipe (2), the pressure measuring pipe (6) is connected with the capillary tube (9) through the plastic pipe (18), and the water pipe (2) passes through The replenishment pipe (19) is connected with the pressure measuring tube (6), the replenishment pipe (19) is controlled by the replenishment pipe switch (20), the sewer pipe (2) is equipped with a sewer switch (3), and the tee joint (4) is equipped with three Through the switch (5), the pressure measuring tube (6) is connected with the overflow pipe (7), the overflow pipe (7) is controlled by the overflow pipe switch (8), and the lower permeable stone (10) is covered with coarse sand (11). An upper permeable stone (12) is installed above the sand (11), and filter paper is laid on the surface of the upper permeable stone (12), and a sample (16) is installed on the filter paper, and the sample cylinder (17) is connected to the exhaust pipe (14), and the drain The trachea (14) is controlled by the exhaust pipe switch (13). The sample cylinder (17) is equipped with a plurality of soil-taking hole plugs (15). The thickness of the sample cylinder (17) is greater than 0.5cm, and the inner diameter is greater than 3-4cm. The outer wall of the pressure measuring tube (6) has a scale value, the minimum scale is 1mm, and the 0 point of the scale is located at the top of the scale value, and is flush with the top surface of the upper permeable stone (12).