A deep replacement process using medium and low energy level dynamic compaction for flow-plastic to soft-plastic clay

Abstract

The invention provides a deep replacement process for fluid-plastic to soft-plastic clay using medium and low-level dynamic tamping, which belongs to the technical field of foundation treatment in construction engineering. On the premise of a thinner cushion layer of 50-80cm, a special rammer is used , and use medium and low energy level dynamic compaction to directly replace upwards from the deep layer; the special rammer includes the hook part connected from top to bottom as an integral structure, the anti-buried hammer extension part and the rammer body part, and the anti-buried hammer extended body The height of the part is more than 2.8 meters. The body of the tamper includes the upper trapezoidal circular platform structure and the lower cylinder structure. The outer wall of the tamper body is evenly distributed with a number of semicircular open air holes. The total height of the special rammer is 2 meters. The displacement depth required by the design. The process of the present invention is based on the flow-plastic to soft-plastic clay foundation dynamic compaction replacement special rammer for process change, which solves the "buried hammer" phenomenon and realizes the use of low-energy Level dynamic compaction (3000-4000KN.m) for deep replacement of 6 meters and above.

Description

technical field [0001] The invention belongs to the technical field of foundation treatment in construction engineering, and specifically discloses a deep replacement process for flow-plastic to soft-plastic clay by adopting middle and low energy level dynamic compaction. Background technique [0002] The dynamic compaction replacement method is a kind of foundation treatment technology in the dynamic compaction method. It refers to repeatedly raising the rammer to a high place, causing it to fall freely to form a ramming pit, and continuously backfilling the ramming pit with crushed stones, steel slag, construction waste and Other hard and coarse-grained materials with high strength and good water permeability form a dense pier in the weak foundation to improve the bearing capacity of the foundation and also have a drainage consolidation channel. [0003] In the conventional dynamic compaction replacement, the code stipulates: "The depth of the dynamic compaction replacemen...

AI Technical Summary

Problems solved by technology

[0004] When the replacement object of dynamic tamping is a fluid-plastic to soft-plastic clay foundation, during the free-fall process of the replacement tamper by dynamic ramming, because the fluidity and deformation of the fluid-plastic to soft-plastic clay can be reduced after the tamper is inserted into the deep layer The characteristics of this method are that the soil after the tamping will flow back quickly, and the "buried hammer" phenomenon will occur when the tamping hammer is deeply buried in the ground, resulting in the failure of the dynamic tamping replacement to continue to the designed replacement depth, thus affecting the environmental protection and the replacement of the dynamic tamping. Application of Inexpensive Technology

The traditional solution is to continuously add fillers during tamping to ensure that the hammer is not "buried", but a large amount of fillers prevents "buried hammers", which will form a hard shell of fillers in the shallow layer, making it impossible for medium and low energy level dynamic ram replacement. Penetrate the hard crust, so that the depth of medium and low energy level dynamic compaction replacement (4000KN. , due to the limitation of the lifting height, it is necessary to increase the weight of the tamper to achieve a high energy level; but because of the high water content and high viscosity of this kind of fluid-plastic to soft-plastic clay, the adsorption generated when the tamper is dropped and pulled out The force will be 3-4 times higher than the adsorption force of the general soil foundation when the hammer is drawn, which will cause damage or even damage to the common dynamic compaction equipment and door frames on the market, resulting in safety accidents or equipment damage, which is also impossible to implement.

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