CN113006048A

CN113006048A - Construction method of long spiral drilling retaining wall for soil-squeezing pile

Info

Publication number: CN113006048A
Application number: CN202110206967.5A
Authority: CN
Inventors: 王吉良; 贾君; 童修富; 王宇; 孙权; 姜曦; 曹兴明; 曹宇; 崔伟婷
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-02-24
Filing date: 2021-02-24
Publication date: 2021-06-22

Abstract

The invention discloses a construction method of a long spiral drilling retaining wall for a soil-squeezing pile, which utilizes the characteristic that the forward and reverse rotation soil return directions of a spiral blade of a drilling machine are opposite, forward rotation drilling is carried out, part of residual soil is returned upwards until the drilling is stopped at a preset depth, reverse rotation lifting drilling is carried out, loose soil on a drill rod is filled back to the retaining wall in a hole, and then the soil-squeezing pile is constructed. The method has the advantages of simplicity, practicability, easy popularization, low cost and wide market prospect, can ensure both the side friction resistance and the end resistance of the pile, can be constructed by using a common long spiral drilling machine, and fills the blank of the construction of the soil-squeezing pile.

Description

Construction method of long spiral drilling retaining wall for soil-squeezing pile

Technical Field

The invention relates to the field of soil-squeezing pile construction methods, in particular to a long spiral drilling retaining wall used for a soil-squeezing pile construction method.

Background

The prior art of soil-squeezing piles in the construction market is called 'semi-screw pile and pile-forming method' patent number: ZL 031128265.2, according to "building pile foundation technical specification" call for crowded soil stake, the problem that this invention exists is: when a hard soil layer cannot be drilled and the depth of the hard soil layer cannot reach the design requirement, a long spiral drilling machine is generally adopted to drill a hole firstly, and the part with higher soil body strength is taken out to carry out half-screw pile construction, and the method has two disadvantages: firstly, the side friction resistance (higher) calculated according to the soil-squeezing pile is designed, the soil in the hole is returned to the ground by drilling the hole through the long auger drilling machine, the pile forming property of the soil-squeezing pile in the original design is changed into a non-soil-squeezing cast-in-place pile, and the side friction resistance of the pile is greatly reduced, so that the requirement of the vertical bearing capacity of a single pile cannot be met. And secondly, when the underground water soil layer construction is drilled to the designed depth and the drill is lifted, the underground water flows into the hole under the action of the underground water to drive the soil body of the hole wall to collapse, the original soil layer on the hole wall is disturbed, the lateral resistance of the pile is seriously influenced, and the requirement of the designed bearing capacity cannot be met.

Further, patent No.: 20111073430X "crowded native pile pine soil technology" provides a stake, if the adoption when meeting high strength soil body is short spiral drilling machine drilling, this model only has the drill bit to take helical blade resistance little so be favorable to drilling, step one in this patent specification states that the drill bit diameter ratio is driven 1cm to 5cm big by the rig (polished rod), this step has violated the design principle of "building pile foundation technical specification" JGJ94-2008, surpassed the original state that design stake footpath 1cm to 5cm destroyed the pore wall, serious influence stake side frictional resistance. And secondly, the process of the soil-squeezing pile does not have the process of squeezing the soil of the wall of the pile hole, the calculation theory of designing the soil-squeezing pile is changed, the process is actually changed into a non-soil-squeezing cast-in-place pile process, and the requirements of technical Specifications for building pile foundations, JGJ94-2008 are violated. And step two, the drilling machine drives the drill bit to reversely drill and exit the foundation soil, and the forward rotation speed of the drill bit is 2 times to 3 times of the reverse rotation speed. Understanding 1: the purpose of the drill bit rotating 2-3 times of the forward rotation speed after exiting the ground is to throw off the residual soil on the leaves of the short spiral drill bit by centrifugal force, which is not significant for soil squeezing piles. Understanding 2: the centrifugal force inevitably generated when the drilling machine drives the drill bit to reversely drill and withdraw in the hole at the speed 2-3 times of the forward rotation speed enables the pile diameter larger than the original diameter by 1-5 cm to seriously damage the side frictional resistance of the original soil layer of the hole wall, and the design regulation of the soil-squeezing pile in the technical Specification of building pile foundations JGJ94-2008 is violated.

An effective solution to the problems in the related art has not been proposed yet.

Disclosure of Invention

The invention aims to provide a construction method for a soil-extruding pile by using a long spiral drilling retaining wall, which solves the problems that the pile can reach a final pressure value or hammering penetration degree according to design requirements, but does not influence the design elevation, and how to reduce the soil body strength, not influence the side friction resistance and end resistance of the pile, and smoothly hammering or pressing the pile to the design elevation.

In order to achieve the purpose, the invention provides the following technical scheme: the long spiral drilling protecting wall is used for the construction method of the soil-extruding pile, when the soil layer is hard and has no underground water, a long spiral drilling machine is adopted to drill forward and return part of the residual soil upwards, when the drill is lifted to a preset depth, the residual soil on a drill rod returns to the protecting wall in the backfilling hole during the backward drilling, the diameter of the drilled hole is smaller than the designed pile diameter, and the original soil layer on the side of the pile is not disturbed according to the strength value of the soil layer.

Furthermore, the construction method adopts a long spiral drilling machine to drill forwards until the distance from the pile end is reserved with the thickness of a bearing layer, the soil layer of the cohesive soil is not less than 2d, d is the diameter of the pile, the sandy soil is not less than 1.5d, and the soil of the gravel is not less than 1 d.

Compared with the prior art, the construction method of the long spiral drilling retaining wall for the soil-extruding pile is an incomplete soil-discharging drilling method, the bearing capacity of the pile is not affected even if partial residual soil is discharged, and the requirement of double control of the soil-extruding pile can be completely met. The advantages are that:

1. the diameter of the drilled hole can be reduced under the condition of not influencing the side frictional resistance according to the soil layer strength, and the diameter and the side frictional resistance of the pile cannot be influenced when the hole is loosened through drilling.

2. The method is suitable for the soil layer with or without water, when the drill is lifted, the reverse drill can effectively backfill the loosened soil into the hole, and the specific gravity of the drilled loosened soil is generally far greater than the inward tension of the soil on the side wall of the hole at about 1.6, so that the effect of protecting the wall is effectively achieved, and the strength of the soil body is reduced to a limited extent.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

Fig. 1 is a construction schematic view of a long auger drilling retaining wall for an earth-extruding pile construction method according to an embodiment of the invention.

Detailed Description

The invention is further described with reference to the following drawings and detailed description:

example (b):

the long spiral drilling retaining wall is used for the construction method of the soil-squeezing pile, a long spiral drilling machine is used for drilling before the construction of the soil-squeezing pile, the diameter of the drilled hole is smaller than the designed diameter of the pile, the thickness of a reserved bearing layer is determined according to the strength of a soil body, the thickness of a general cohesive soil layer is not smaller than 2d (d is the diameter of the pile), sandy soil is not smaller than 1.5d, and gravel soil is not smaller than 1 d. When the soil layer strength is higher, the reserved soil layer is thinner, and the original soil layer state designed and used at the pile side and the pile end is not disturbed, please refer to fig. 1. The construction sequence is as follows:

1. positioning a drilling machine;

2. drilling in a forward rotation mode until the thickness of the soil layer at the side and the end of the reserved pile is reached;

3. the residual soil on the drill rod is returned into the hole for wall protection while the drill rod is lifted in a reverse rotating mode;

4. and (5) constructing a soil-extruding pile.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art will understand that various changes, modifications and substitutions can be made without departing from the spirit and scope of the invention as defined by the appended claims. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The long spiral drilling protecting wall is used for the construction method of the soil-extruding pile, and is characterized in that when the soil layer is hard and has no underground water, a long spiral drilling machine is adopted to drill forward and return part of residual soil upwards, when the drill is lifted to a preset depth and the drill is reversely drilled, the residual soil on a drill rod returns to the protecting wall in a backfilling hole, the diameter of the drilled hole is smaller than the designed pile diameter, and the original soil layer on the side of the pile is taken as the standard according to the strength value of the soil layer without disturbance.

2. The long auger drilling retaining wall for soil-extruding pile construction method according to claim 1, wherein the construction method is characterized in that a retaining layer thickness is reserved when a long auger drilling machine is adopted to drill forwards to a distance from the pile end, the soil layer of the cohesive soil is not less than 2d, d is the diameter of the pile, the sandy soil is not less than 1.5d, and the soil of crushed stone is not less than 1 d.