Test device for salt expansion characteristic of salinized soil under rigidity constraint condition

Abstract

The invention relates to a test device for the salt expansion characteristic of salinized soil under the rigidity constraint condition. The test device comprises a temperature control box (1), a support frame (2), a sample barrel (3), a rigidity constraint mechanism, and a test data detection assembly, wherein the support frame (2) and the sample barrel (3) are arranged inside the temperature control box. With selection of different rigidity constraint mechanisms, different rigidity constraint changing environments are provided and the corresponding rigidity constraint condition is formed by cooperating with the movability of a mandril. The temperature control box adjusts the soil sample temperature to realize freeze-thaw cycle tesst under different rigidity constraints. Besides, a water injection port (27), a weighing device (11), a water adding asembly (17) and an air drying assembly and other parts are added, so that the dry-wet cycle tests and dry-wet freeze-thaw coupling tests under different rigidity constraint conditions are realized. The test device is operated simply and is assembled conveniently; the salt expansion amount and the salt expansion force in the salt expansionprocess of the sample can be measured simultaneously; the moisture content and temperature change of the sample are monitored; and the data are automatically collected.

Description

technical field [0001] The invention relates to the technical field of testing the salt expansion characteristics of saline soil, in particular to a test device for the salt expansion characteristics of saline soil under stiffness constraints. Background technique [0002] Saline soil is a general term for all kinds of salinized and alkalized soils. According to distribution, it is mainly divided into inland saline soil, coastal saline soil and plateau saline soil. my country's saline soil area is about 200,000 square kilometers, ranking fourth in the world. Na 2 SO 4 Saline soil is widely distributed in inland and plateau regions of my country, and salt swelling is one of its main disease types. Taking the Qinghai-Tibet Plateau as an example, the soil salinization in this area is serious, and the geographical environment of this area is special, with high altitude, large temperature difference, strong solar radiation, and severe freeze-thaw cycle. At the same time, wit...

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Problems solved by technology

In addition, the saline soil in the actual site is under complex periodic meteorological conditions such as dry-wet cycle and freeze-thaw cycle. The test results under a single test condition cannot truly reflect the actual salt expansion characteristics of the saline soil. Guidance for actual specific projects very limited

[0005] 2. The measurement parameters are single, and only the amount of salt swelling during the test can be measured. Since the salt swelling force in the test is always equal to the overlying load, it is impossible to monitor the evolution mechanism of the salt swelling force during the salt swelling process of the soil, and it is impossible to measure the salt swelling force. Carry out relevant research and analysis on swelling force, and the degree of automatic data collection is low

Air blowing from one side will lead to uneven distribution of moisture content of the sample. During the drying process, due to the low moisture content of the sample at the air inlet, the water and salt will continue to migrate to the air inlet, which will greatly cause the unevenness of the sample’s salt expansion, and This inhomogeneity increases as the experiment progresses

[0007] 4. Since the test soil is sulfuric acid saline soil, chlorine saline soil, etc., the humidity sensor used for moisture content monitoring is generally a TDR sensor based on the principle of time domain reflection, and its measurement results are greatly affected by soluble salt ions (especially SO 4 2- ), the error can reach more than ±5%. For the dry-wet cycle test, the moisture content measurement error should be within ±1%, which leads to extremely unreliable test results, and the TDR sensor is generally large, which will cause soil cause great disturbance

At the same time, due to the uneven distribution of the moisture content of the sample during the drying process, the humidity sensor can only monitor the moisture content of a certain area of ​​the soil sample, and cannot truly reflect the actual moisture content of the overall soil sample.

[0008] 5. The sample barrel is a barrel-in-barrel complex segmented structure, which is cumbersome to assemble and cannot realize the visualization of the sample barrel

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