An In-Situ Shear Experiment Apparatus for Determination of Saturated Loess-mudstone Contact Surface

Abstract

An in-situ shear experimental instrument for measuring the contact surface of saturated loess-mudstone. The lower shear box is installed in the experimental foundation pit. The upper shear box is installed on the lower shear box. The upper shear box is connected to the inner wall of the experimental foundation pit. A horizontal hydraulic jack is set horizontally in the middle; a shear box pressure cover is installed on the top of the upper shear box. The shear box pressure cover is connected to the counterweight support plate through the axial hydraulic jack, and the counterweight support plate is equipped with a counterweight; in the experimental foundation pit The water container is also installed through the water container support rod, and the water container is connected to the water inlet hole on the upper part of the upper shear box through a water pipe, so that the injected water flows out from the lower part of the upper shear box. The in-situ shear tester provided by the present invention can truly reflect and keep the contact surface between loess and mudstone in a state of overhumidity, saturation and soft plastic for a long time in situ without disturbing the soil. The size of the test sample is large, which is an ideal way to obtain loess- An effective instrument for in-situ instantaneous shear strength and long-term creep shear strength parameters of "heterogeneous soil" at the mudstone contact surface.

Description

technical field [0001] The invention relates to the technical field of in-situ testing, in particular to an in-situ shear tester for measuring the contact surface of saturated loess-mudstone. Background technique [0002] The in-situ shear test is actually to measure the shear strength of the rock-soil body itself when the rock-soil body moves along the weak surface or the contact surface under the action of external force; measure the shear strength of the test object under different axial pressures, and obtain the soil strength. The shear strength index cohesion c and friction angle ψ can calculate the stability of geological bodies such as landslides. [0003] At present, in situ shear experiments are mostly experiments on the same rock and soil, such as pure loess, pure gravel soil, etc. For the "loess-mudstone contact surface" landslides that are widely developed in Northwest China, there are few studies on loess and mudstone. The in-situ shear experiment under the sat...

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Problems solved by technology

[0003] At present, in situ shear experiments are mostly experiments on the same rock and soil, such as pure loess, pure gravel soil, etc. For the "loess-mudstone contact surface" landslides that are widely developed in Northwest China, there are few studies on loess and mudstone. The in-situ shear experiment under the saturated state between the contact surfaces shows that the reason why this kind of loess-mudstone contact surface can cause disasters is that there is a large difference in water permeability between the upper and lower contact surfaces. The water permeability of loess is much greater than that of mudstone. After infiltration, it gathers at the rock-soil contact surface, making the loess on the contact surface saturated by water and staying in a state of over-saturated soft plastic for a long time, reducing the strength of the loess

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