Method for determining shear strength of chemically polluted soil and special full-automatic direct shear apparatus

Abstract

The invention discloses a method for determining the shear strength of chemically polluted soil and a special full-automatic direct shear apparatus. A chemical corrosion device is added for the direct shear apparatus compared with the prior art, infiltration holes are formed in the bottom of a shear box, and a notch groove is formed in the bottom of a container trough of the chemical corrosion device, so that when the method is adopted for determining, a chemical corrosion solution can be directly injected into the container trough to perform sealed maintenance; after maintenance is completed, vertical pressure loading is directly performed to complete a full-automatic direct shear test so that the pollutant corrosion situation of a soil body on site can be simulated, destroying-free maintenance of a tested soil sample is achieved, the influence of stress release in the sampling process is avoided, disturbance suffered by the soil body is reduced as far as possible, and the tested sample can be closer to the in-situ soil sample in property. In addition, due to the fact that the infiltration rate fluctuation of the chemical corrosion solution is smaller, a result is closer to the polluted situation of natural soil, corrosion distribution can be relatively uniform, the influence of local corrosion on the mechanical property determination of the soil sample is avoided, and the problem that a conventional direct shear apparatus cannot detect the shear strength and parameters of the chemically polluted soil is solved.

Description

technical field [0001] The invention belongs to the field of civil engineering instrument testing, and in particular relates to a method for measuring the shear strength of chemically polluted soil and a special automatic direct shear instrument. Background technique [0002] The foundation soil layers of most industrial factories are eroded and damaged by chemical pollutants to varying degrees, resulting in attenuation of soil strength and bearing capacity, which in turn leads to uneven settlement, deformation, instability and damage of superstructure structures. In view of the particularity of the boundary environment of the foundation soil layer in industrial factories, the corrosion of chemical solutions should be considered in the design process of the bearing capacity of the foundation soil layer, which is very important to reasonably determine the bearing capacity and strength parameters of the foundation soil layer. [0003] At present, in order to determine the bear...

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Problems solved by technology

In recent years, the soil has been more and more affected by the external environment, and the traditional direct shear instrument can no longer accurately obtain the basic parameters of the soil.

Although "a fully automatic digital large-scale frozen soil direct shear instrument" (CN102313673B), "frozen soil-structure direct shear instrument and its use method" (CN102252919B), "temperature-controlled direct shear instrument" (CN102230868B) and "large multi- "Functional Frozen Soil-Structure Contact Surface Cyclic Direct Shear Apparatus and Test Operation Method" (CN102798575B) have improved the traditional direct shear apparatus to adapt to the direct shear test of structural soil in complex environments. However, these devices only solve To solve the problems of complex soil shear test in civil engineering and traffic engineering design under cold conditions, the existing geotechnical direct shear instrument still cannot meet the requirements of direct shear test of soil samples under the coupling of chemical solution and load. The measurement method of the instrument will inevitably cause large deviations in the measurement results.

This is because, on the one hand, the existing geotechnical direct shear instruments usually measure the shear strength of the sample corroded by the chemical solution under a certain load, and it is impossible to realize the synchronization of the chemical solution and the load on the sample. Therefore, compared with the parameters required in actual engineering, there is a big difference, and the guiding significance is limited; The difference in the properties of the in-situ soil sample will have a great impact on the measurement of the mechanical properties of the soil sample, and will also cause deviations in the measured parameters

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