Raft foundation bottom soil body void deformation monitoring device

Abstract

The invention discloses a raft foundation bottom soil body void deformation monitoring device which comprises a steel plate located under a raft and arranged horizontally. An anchoring rod used for being anchored under the raft is arranged on the bottom face of the steel plate, an inner steel bar vertically arranged is fixed on the top face of the steel plate, a raft steel pipe vertically arranged and poured with the raft integrally is sleeved on the outside of the inner steel bar, the outer diameter of the inner steel bar is smaller than the inner diameter of the raft steel pipe, an outer protection pipe fixed on the inside of an embankment is sleeved on the outside of the raft steel pipe, and the outer diameter of the raft steel pipe is smaller than the inner diameter of the outer protection pipe. The monitoring device has the advantages of facilitating tests, being high in measuring accuracy, good in adaptability, good in long-term effectiveness and low in cost, and can be widely applied to the technical field of foundation deformation monitoring.

Description

technical field [0001] The invention relates to the technical field of foundation deformation monitoring, in particular to a monitoring device for void deformation monitoring of soil at the bottom of a raft foundation. Background technique [0002] Reinforced concrete pile-raft structure (pile-slab structure) can be used in projects such as deep and thick soft foundations, collapsible loess foundations, subgrade transition sections, and turnout area subgrades with strict settlement control. Due to its obvious advantages, it has been used in high-speed railway subgrades in recent years It has also been widely used in engineering. [0003] However, when the project site is of underconsolidated foundation soil, filling soil, loose soft soil, collapsible loess, saline soil and other types of foundation soil, with the occurrence of foundation soil settlement and deformation in the later stage, the foundation soil at the bottom of the raft will often appear The void phenomenon of...

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Problems solved by technology

[0003] However, when the project site is of underconsolidated foundation soil, filling soil, loose soft soil, collapsible loess, saline soil and other types of foundation soil, with the occurrence of foundation soil settlement and deformation in the later stage, the foundation soil at the bottom of the raft will often appear The void phenomenon of the raft slab causes the pile foundation under the raft slab to be exposed, which not only reduces the durability of the pile raft structure (pile slab structure), but also affects its mechanical characteristics under dynamic loads such as trains, which seriously reduces the effect of foundation reinforcement

[0004] At present, there are two main methods for testing the void deformation of the foundation soil under the raft slab: 1. By embedding an earth pressure cell to monitor the contact force between the soil between the piles at the bottom of the raft slab and the raft slab, to indirectly reflect whether there is a void in the foundation soil This method can only reflect whether there is a void at the bottom of the raft, but cannot reflect the degree and value of the void deformation, and the long-term effectiveness of the earth pressure cell is insufficient; 2. In the foundation soil and on the raft Set up the components for settlement deformation monitoring respectively, and use the difference between the two measured deformations to reflect whether there is a void phenomenon in the foundation soil, and measure the value of the void deformation

Usually, the deformation of the raft is monitored by embedding a settlement plate, and the monitoring accuracy of the settlement plate is generally about 1 mm, which is not enough; the settlement deformation of the foundation soil is generally measured by a single-point settlement meter, and the long-term effectiveness of the components is relatively low. hard to get guarantee

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