Multifunctional road soil roadbed freezing and thawing circulating test device

Abstract

The invention discloses a multifunctional road soil roadbed freezing and thawing circulating test device. During a freezing and thawing circulating test, six samples are placed among six top plate heat exchangers and six bottom plate heat exchangers of a constant temperature system; the six top plate heat exchangers and the six bottom plate heat exchangers are respectively connected in parallel with a refrigeration circulating machine set; a moisture replenishment system is connected with the bottoms of six roadbed soil samples; a temperature sensor and a soil moisture sensor of a test systemare respectively buried in the six roadbed soil samples of the samples; a displacement sensor of the test system is in contact with the top of the top plate heat exchanger of a temperature control system; and the temperature sensor, the displacement sensor and the soil moisture sensor are connected with an acquisition channel of a data acquisition instrument of a data acquisition system. The multifunctional road soil roadbed freezing and thawing circulating test device has the advantages of simple structure, convenient use, high test precision and reliable result, can better complete the parallel test measurement of the engineering design parameters of roadbed soil modulus of resilience, CBR (Constants Bit Rate) intensity, and the like in a seasonal frost region under a least favorable state, which cannot be achieved by the traditional devices, and can directly provide necessary design parameters for engineering design.

Description

Technical field [0001] The invention relates to a technical field used for roadbed soil tests in seasonal frozen soil areas, and more specifically to a multifunctional road soil foundation freeze-thaw cycle test device, which is adapted to the complex temperature and moisture boundary conditions of roadbed soil tests in seasonal frozen areas And parallel test requirements, so as to realize the engineering design parameter determination of subgrade soil elastic modulus and CBR strength in the most unfavorable conditions. Background technique [0002] The distribution area of ​​seasonal frozen soil in my country is very wide, covering areas with latitude higher than 24°, and its distribution area is 5.137×10 6 km 2 , Accounting for 53.5% of the land area. The roadbeds or foundations of linear structures such as highways and railways in the seasonally frozen area all change with winter and summer, and the soil is frozen and melted. This phenomenon is called the freeze-thaw cycle. D...

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Problems solved by technology

[0007] The author conducted a survey on the domestic units engaged in frozen soil research and frozen soil engineering design. The current situation of freeze-thaw test equipment is as follows: The freeze-thaw test equipment represented by the Key Laboratory of Frozen Soil Engineering of the Chinese Academy of Sciences can only consider water migration in an open system. Only one soil sample test can be completed at a time, which cannot meet the requirements of a group of parallel tests of soil sample mechanical indicators; the main function of the test device introduced in the invention patent "Mechanical Parameters Test Machine for Subgrade Materials under Freeze-Thaw Cycles" introduced by Professor Liu Hanbing of Jilin University is to operate under dynamic loads. During the process of freezing and thawing, the dynamic characteristic parameters of subgrade materials, frost heave, and pavement deflection are tested, but the underground water supply cannot be considered, and the direct connection with the current standard elastic modulus and CBR test conditions cannot be completed, and parallel tests cannot be carried out at the same time. ; There are other universities or research institutes in China that directly put the soil column into the refrigerator for freeze-thaw cycle test. This method is not only completely different from the freezing mode of the soil column (temperature gradient state) and the freezing mode of subgrade soil in seasonally frozen areas, but also cannot simulate Moisture recharge and migration process in soil foundation during freeze-thaw process

[0008] At present, the existing test devices can not meet the mechanical index test requirements in the most unfavorable state of the seasonally frozen area. Therefore, the development can not only simulate the process of water replenishment and migration in the soil foundation during the freeze-thaw process, but also ensure the top and bottom plates of several soil samples. The temperature is the same and changes synchronously, so as to ensure that the initial state and temperature state of the repeatedly frozen-thawed soil sample are the same to meet the requirements of the "Highway Geotechnical Test Regulations" for parallel samples, and the sample size must be consistent with the elastic modulus and CBR test device It is very urgent to solve the problem of the direct docking test device to test the rebound modulus and strength parameters of subgrade soil in seasonally frozen regions under the most unfavorable conditions

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