Method for observing and calculating depth of newly-generated swelling shrinking deformation of excavation expansive soil slope surface

Abstract

The invention discloses a method for observing and calculating depth of newly-generated swelling shrinking deformation of an excavation expansive soil slope surface. The method comprises the following steps of: carrying tracking observation by embedding a displacement meter in a shallow shaft, carrying out time effect statistic analysis on an observation result based on assumption of linear attenuation of the swelling shrinking deformation along the depth of the slope surface, and calculating the depth of the swelling shrinking deformation of a slop surface soil body under the action of weather by utilizing a linear equation on the premise of reasonable linear assumption verified by observation data. The method for observing and calculating the depth of the newly-generated swelling shrinking deformation of the excavation expansive soil slope surface, disclosed by the invention, overcomes difficulty that a fixed point is hard to exactly arrange by a surface mark measurement method, also has the advantages of high precision of the observation data and small influence by personal factors compared with the surface mark measurement method, and is reasonable in calculating method and simple and convenient to calculation; and analysis parameters of a protection design matching conditions of local weather can be provided for a protective barrier of the excavation expansive soil slop surface through the results obtained by the observation and the calculation according to the method disclosed by the invention.

Description

technical field [0001] The invention relates to a protection method for highway expansive soil slopes, in particular to an observation and calculation method for the depth of new expansion and contraction deformation of excavated expansive soil slopes. Background technique [0002] Expansive soil is a special soil that contains montmorillonite minerals and has poor engineering properties of water absorption expansion and loss of water shrinkage. The excavation will change the soil mass of expansive soil slope from the relatively deep soil mass before excavation to the surface soil mass. The expansion and contraction deformation activities of the excavated expansive soil slope form a new expansion and contraction deformation activity zone on the excavated slope and induce slope cracking deformation and slide collapse of the expansive soil excavation slope. For this reason, it is necessary to accurately measure the new expansion and contraction deformation depth of the excava...

AI Technical Summary

Problems solved by technology

Since there are expansion-contraction deformation active zones in the non-excavation surface of the expansive soil area, it is very difficult to set the fixed point for observation, so it is difficult to accurately observe the new expansion-contraction deformation of the excavated slope by this method

At present, due to the lack of accurate observation and calculation methods for the depth of the new expansion and contraction deformation active zone on the excavated slope, the protection engineering design of excavated expansive soil slopes is often still designed according to the conventional protection depth (such as skeleton + grass protection, the general protection depth is 0.5 m~1.0m)

In fact, the new expansion and contraction deformation depth of the excavation slope is between 1.11m and 2.47m, which shows that the shallow protection depth is the main reason for the general failure of expansive soil excavation slope protection by conventional slope protection engineering

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