Construction method of grating conjoined cement soil in karst foundation

Abstract

The invention discloses a construction method of grating conjoined cemented soil in a karst foundation, which comprises the following steps: constructing grating conjoined stiff composite piles, in the grating conjoined stiff composite piles, the pile ends of most of the stiff composite piles are positioned above a karst cave and abut against a karst top plate, and the pile ends of the most stiff composite piles are positioned above the karst cave and abut against the karst top plate; the cement soil peripheral piles of a small part of the stiff composite piles are located above a karst top plate, and core piles penetrate through a karst cave to abut against a karst bottom plate. The foundation is stable, and the pile foundation performance is reliable.

Description

Technical Field

[0001] The invention relates to a construction method of grid-connected cement soil in a karst foundation. Background Art

[0002] In the construction of piles in karst foundations, generally only the pile end is placed above the karst roof. For some places where the karst roof is weak, the pile will sink, affecting the performance of the pile foundation. Summary of the invention

[0003] The purpose of the present invention is to provide a construction method of grid-connected cement soil in karst foundation with reliable pile foundation performance.

[0004] The technical solution of the present invention is: A construction method of grid-connected cement-soil in karst foundation includes construction of grid-connected rigid composite piles, and is characterized in that: among the grid-connected rigid composite piles, the pile ends of most of the rigid composite piles are located above the karst cave and are on top of the karst top plate, and the cement-soil peripheral piles of a small part of the rigid composite piles are located above the karst top plate, and the core piles pass through the karst cave and are on the karst bottom plate.

[0005] The grid-connected rigid composite piles and the underground continuous wall supporting the foundation pit form an overall underground integrated structure.

[0006] In the grid-connected cement soil, overload stabilization and ultra-high strength thickened pipe piles are used to verify the strength of the karst roof.

[0007] Construction of cement-soil outer piles of rigid composite piles: high-pressure blasting and splitting, high-speed mixing and drilling rod shaking, and spiral blade back pressure expansion for densification and softening; construction of core piles of rigid composite piles: rapid pressing of pipe piles in the flow plastic and soft plastic state of cement soil; regulation of cement soil properties in different parts: plastic upper part, re-mixing and re-spraying of cement aggregate in the lower bearing layer, and back pressure expansion to form hard plastic, so as to achieve the ultimate compaction of cement soil, soil around piles, and soil at pile ends by overloading, high energy, and steady pressure.

[0008] When the outer cement soil is in a plastic state, the core pile of the overloaded pressure-stabilizing rigid composite pile is penetrated with a core weight of 500-800 tons to reach the pile end, verifying that the karst top plate and the soil layer above have a certain thickness, strength and stability. At the same time, CT and acoustic electromagnetic geophysical radar are used to explore the location and distribution range of the cave to see whether the pile end resistance of 500-800 tons can be met. If the 500-800 ton end resistance cannot be balanced, the core pile will pass through the upper cave and reach the position where it can achieve balance.

[0009] The invention has a stable foundation and reliable pile foundation performance.

[0010] The present invention will be further described below in conjunction with the embodiments. DETAILED DESCRIPTION

[0011] A construction method of grid-connected cement-soil in a karst foundation comprises the construction of grid-connected rigid composite piles, wherein the pile ends of most of the rigid composite piles are located above a karst cave and are on top of a karst top plate, and the cement-soil peripheral piles of a small part of the rigid composite piles are located above the karst top plate, and the core piles pass through the karst cave and are on top of a karst bottom plate.

[0012] When the outer cement soil is in a plastic state, the core pile of the overloaded pressure-stabilizing rigid composite pile is penetrated with a core weight of 500-800 tons to reach the pile end, verifying that the karst top plate and the soil layer above have a certain thickness, strength and stability. At the same time, CT and acoustic electromagnetic geophysical radar are used to explore the location and distribution range of the cave to see whether the pile end resistance of 500-800 tons can be met. If the 500-800 ton end resistance cannot be balanced, the core pile will pass through the upper cave and reach the position where it can achieve balance.

[0013] The grid-connected rigid composite piles and the underground continuous (SMW, bored cast-in-place piles, rigid composite piles and other supports, using quantitative analysis to determine whether to construct long piles) walls of the foundation pit support form an overall underground integrated structure.

[0014] In the grid-connected cement soil, overload pressure stabilization and ultra-high strength thickened pipe piles are used to verify the strength of the karst roof (the pressure stabilization value when the roof is reached).

[0015] Construction of cement-soil outer piles of rigid composite piles: high-pressure blasting and splitting, high-speed mixing and drilling rod shaking, spiral blade back pressure expansion for densification and softening; construction of core piles of rigid composite piles: rapid pressing of pipe piles in the flow plastic and soft plastic state of cement soil; regulation of cement soil properties in different parts: plastic upper part, re-mixing and re-spraying of cement aggregate in the lower bearing layer, back pressure expansion to form hard plastic, to achieve the ultimate compaction of cement soil, soil around piles, and soil at pile ends (large range of stress bubbles and high energy, full-domain dynamic response) with overload (greater than the limit value), high energy (equivalent to prestress), and steady pressure (steady pressure value is mainly the resistance of pile bottom) to achieve the ultimate compaction of cement soil, soil around piles, and soil at pile ends (large range of stress bubbles and high energy, full-domain dynamic response).

Claims

1. A construction method of grid-connected cement soil in karst foundation, comprising the construction of grid-connected rigid composite piles, characterized in that: Among the grid-connected rigid composite piles, the pile ends of most of the rigid composite piles are located above the karst cave and are on top of the karst roof. For a small number of rigid composite piles, the cement-soil outer piles are located above the karst roof, and the core piles pass through the karst cave and are on the karst bottom plate.

2. The construction method of grid-connected cement soil in karst foundation according to claim 1 is characterized by: The grid-connected rigid composite piles and the underground continuous wall supporting the foundation pit form an overall underground integrated structure.

3. The construction method of grid-connected cement soil in karst foundation according to claim 1 or 2, characterized in that: In the grid-connected cement soil, overload stabilization and ultra-high strength thickened pipe piles are used to verify the strength of the karst roof.

4. The construction method of grid-connected cement soil in karst foundation according to claim 1 or 2, characterized in that: Construction of cement soil peripheral piles for rigid composite piles: high-pressure blasting and splitting, high-speed mixing drill rod shaking, spiral blade back pressure expansion, densification, and softening; construction of core piles for rigid composite piles: quickly press the pipe piles into the cement soil in the fluid plastic and soft plastic state; Regulate the properties of cement soil in different parts: the upper part is plastic, the lower bearing layer is repeatedly mixed and sprayed with cement aggregate, and the back pressure is used to expand the diameter to form hard plastic, so as to achieve the limit of pile-soil compaction of cement soil, soil around the pile, and soil at the pile end by overloading, high energy, and steady pressure.

5. The construction method of grid-connected cement soil in karst foundation according to claim 1 or 2, characterized in that: When the outer cement soil is in a plastic state, the core pile of the overloaded pressure-stabilizing rigid composite pile is penetrated with a core weight of 500-800 tons to reach the pile end, verifying that the karst top plate and the soil layer above have a certain thickness, strength and stability. At the same time, CT and acoustic electromagnetic geophysical radar are used to explore the location and distribution range of the cave to see whether the pile end resistance of 500-800 tons can be met. If the 500-800 ton end resistance cannot be balanced, the core pile will pass through the upper cave and push to a position where it can achieve balance.