Structure for lowering, reinforcing, lifting and leveling the pile foundation platform structure and construction methods for it

Abstract

Structure for lowering, reinforcing, raising, and leveling the pile foundation platform structure, comprising a platform and several pile foundations rigidly connected to the lower part of the platform; characterized in that the structure further comprises: a soft soil reinforcement layer below the platform, wherein the platform is located above the soft soil reinforcement layer below the platform; and wherein several first injection holes are provided in the soft soil reinforcement layer below the platform, and wherein the first injection holes are connected to the outside through the platform;and wherein the first injection holes are used to perform an initial injection for the interior of the soft soil reinforcement layer below the platform in order to complete the reinforcement for the soft soil reinforcement layer below the platform, and wherein an upward reaction force is generated by means of the injection pressure to slowly raise the platform to the permissible deviation range; a pile tip support layer located below the soft soil reinforcement layer below the platform, wherein several second injection holes are provided on the pile tip support layer, and wherein the second injection holes are connected to the exterior by passing through the platform and the soft soil reinforcement layer below the platform;and wherein the second injection holes are used to carry out a second injection for the interior of the support layer of the pile tip in order to form a composite foundation to support the pile foundation.;

Description

TECHNICAL FIELD

[0001] The present invention relates to the technical field of building facilities, particularly to a structure for lowering, reinforcing, raising and leveling the pile foundation platform structure and a construction method thereof. STATE OF THE ART

[0002] In residential and industrial construction, the backfill soil layer or soft foundation is treated prior to construction. Under the condition that there is no natural foundation, piles are driven as the foundation for most buildings, and then the superstructure is constructed. In the field of bridges, the pile foundation platform structure is also the main form of the bridge foundation. Due to the lack of impermeability of the foundation, the foundation soil layer has greater compressibility and the foundation bearing capacity is insufficient.When the groundwater drainage conditions change, groundwater erosion occurs, resulting in a reduction of the foundation bearing capacity; or due to the existence of a weak interlayer between the pile tip and the bedrock or too large slope of the rock surface, the depth of the pile tip protruding into the rock is insufficient, resulting in side slip; or the loose soil layer around the pile and the low friction coefficient and other factors cause uneven subsidence of the pile foundation.Therefore, the platform needs to be lifted and leveled, and the pile tip support layer needs to be grouted and reinforced to meet the foundation load-bearing capacity requirements and the design allowable settlement range, reduce the height difference between the pile foundations of the building, and ensure the structural safety of the factory building, house, or bridge.

[0003] Document CN 2 07 228 186 U proposes a composite foundation for strengthening and correcting buildings, including a pile foundation beneath the bedding layer, a foundation stabilization platform, and a column. The bedding layer is formed from a reinforcement layer consisting of the original bedding layer and the hardened mortar, and slurry is injected into the original bedding layer through the injection holes for bedding reinforcement. CONTENT OF THE PRESENT INVENTION

[0004] The present invention provides a structure for lowering, reinforcing, lifting, and leveling the pile foundation platform structure and a construction method therefor. The present invention uses the following technical solution: a structure for lowering, strengthening, raising and leveling the pile foundation platform structure, comprising: a platform and several pile foundations that are firmly connected to the lower part of the platform; a soft soil reinforcement layer below the platform, the platform being located above the soft soil reinforcement layer below the platform; and wherein a plurality of first injection holes are provided on the soft soil reinforcement layer below the platform, and wherein the first injection holes are connected to the outside through the platform; and wherein the first injection holes are used to perform initial injection for the interior of the soft soil reinforcement layer below the platform to complete the reinforcement for the soft soil reinforcement layer below the platform, and wherein an upward reaction force is generated by means of the injection pressure to slowly raise the platform to the allowable deviation range; a pile-topping support layer located below the soft soil reinforcement layer below the platform, wherein a plurality of second injection holes are provided on the pile-topping support layer, and wherein the second injection holes are connected to the exterior through the platform and the soft soil reinforcement layer below the platform; and wherein the second injection holes are used to perform a second injection for the interior of the pile-topping support layer to form a composite foundation for supporting the pile foundation.

[0005] Preferably, the plurality of first injection holes and the plurality of second injection holes are each arranged uniformly symmetrically.

[0006] Preferably, the hole diameter of the first injection holes and the second injection holes is 42 mm each.

[0007] Preferably, the liquid mortar used for the first injection and the second injection is a liquid mortar with two components, wherein the liquid mortar with different components is pressed and combined into the soil body at the outlet of the injection pipe and reacts and sets, and wherein the initial setting time is 5-60 s.

[0008] A structural construction method for lowering, strengthening, lifting and leveling the pile foundation platform structure, comprising the following steps: Determining the hole positions and the number of injection holes; wherein the hole positions are provided on the two sides of the pile foundation and are distributed symmetrically; and wherein the number of injection holes is more than 1; drilling at all hole positions using a drilling machine to form a plurality of first injection holes; using an integrated drilling and injection machine after the formation of the plurality of first injection holes to simultaneously perform initial injection for the soft soil reinforcement layer below the platform through the plurality of first injection holes, respectively, using a segmented drilling and injection method, so that the platform is smoothly and slowly raised to the allowable deviation range; After the platform has become stable, all integrated drilling and injection machines continue to drill down to the bottom of the pile foundation, after which several second injection holes are formed; each using an integrated drilling and injection machine after the formation of the plurality of second injection holes to simultaneously perform a second injection for the pile head support layer through the plurality of second injection holes each with a segmented drilling and injection method until the pile head support layer forms a U-shaped composite foundation for supporting the pile foundation.

[0009] Preferably, the segmented injection used for the initial injection comprises a first injection segment, a second injection segment, a third injection segment and a fourth injection segment, wherein the first injection segment has a depth of 2 m, and wherein the second injection segment, the third injection segment and the fourth injection segment each have a depth of 1 m.

[0010] Preferably, the initial setting time of the liquid composite injection mortar used for the initial injection is 10-20 s, with the diffusion radius of the liquid mortar being 1.5-2.0 m.

[0011] The injection pressure during the first injection is preferably 0.8-1.5 MPa.

[0012] Preferably, the initial setting time of the liquid composite injection mortar used for the second injection is 20-40 s, with the diffusion radius of the liquid mortar being 2.0-3.0 m.

[0013] The injection pressure for the second injection is preferably 0.6-1.2 MPa.

[0014] The present invention has the following advantages: The construction is carried out using a reinforcement and lifting method, in particular, the novel technologies and processes such as "platform lifting and leveling" and "pile head support layer strengthening" are comprehensively adopted, whereby an enlarged composite foundation beam is formed at the bottom of the platform and the strength of the pile head support layer is improved, so that the load of the upper part is evenly transferred to the support layer. With this solution, the goal of lowering and lifting and leveling of the pile foundation platform structure is successfully achieved, so as to meet the requirements of the foundation bearing capacity and the design settlement deviation range. There are the advantages of small construction work area, trouble-free construction, and can improve the foundation bearing capacity and the dual effect of lifting and leveling.

[0015] Of course, any product according to the present invention may not necessarily achieve all of the mentioned advantages at the same time. SHORT DESCRIPTION OF THE DRAWING

[0016] In order to more clearly explain the embodiments of the present invention or the technical solutions of the prior art, the figures to be used in the explanation of the embodiment will be briefly introduced below. Obviously, the figures described below represent only some embodiments of the present invention. Those of ordinary skill in the art can obtain other figures based on the figures without requiring creative work. Fig. 1 shows a schematic structural view of a structure for lowering, reinforcing, lifting and leveling the pile foundation platform structure in an embodiment of the present invention. Fig. 2 shows a plan view of a structure for lowering, reinforcing, lifting and leveling the pile foundation platform structure in one embodiment of the present invention. List of reference symbols 1 platform 2 pile foundation 3 Reinforcement layer for soft ground below the platform 4 First injection hole 5 Support layer of the pile tip 6 Second injection hole DETAILED DESCRIPTION

[0017] In conjunction with figures in the embodiment of the present invention, the technical solutions in the embodiment of the present invention will be explained clearly and completely below. Obviously, the explained embodiments do not represent all embodiments, but only a part of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention should be considered to be covered by the scope of the present invention. Example

[0018] As in Fig. 1 and Fig.2, a structure for lowering, reinforcing, raising, and leveling the pile foundation platform structure in one embodiment of the present invention, comprising a platform 1 and a plurality of pile foundations 2 fixedly connected to the bottom of the platform 1; a soft soil reinforcing layer below the platform 3, wherein the platform 1 is located above the soft soil reinforcing layer below the platform 3; and wherein a plurality of first injection holes 4 are provided on the soft soil reinforcing layer below the platform 3, and wherein the first injection holes 4 are connected to the outside through the platform 1;and wherein the first injection holes 4 are used to perform initial injection for the interior of the soft soil reinforcement layer below the platform 3 to complete the reinforcement for the soft soil reinforcement layer below the platform 3, and wherein an upward reaction force is generated to slowly raise the platform 1 to the allowable deviation range; a pile tip support layer 5 located below the soft soil reinforcement layer below the platform 3, wherein a plurality of second injection holes 6 are provided on the pile tip support layer 5, and wherein the second injection holes 6 are connected to the exterior through the soft soil reinforcement layer below the platform 3 and the platform 1;and wherein the second injection holes are used to perform a second injection for the interior of the support layer of the pile tip 5 to form a U-shaped composite foundation for supporting the pile foundation 2;

[0019] Preferably, the plurality of first injection holes and the plurality of second injection holes are each arranged uniformly and symmetrically. The hole diameter of the first injection holes and the second injection holes is 42 mm each. The liquid mortar used for compaction injection, as well as for injecting mortar and reinforcing, is a liquid mortar with two components. The liquid mortar with different components is pressed into the soil body at the outlet of the injection pipe, combined, and reacts and sets, and the initial setting time is 5-60 seconds.

[0020] An embodiment of the present application may further provide a structural construction method for lowering, strengthening, lifting and leveling the pile foundation platform structure, the method comprising the following steps: Determining the hole positions and the number of injection holes; wherein the hole positions are provided on the two sides of the pile foundation and are distributed symmetrically; and wherein the number of injection holes is more than 1, and wherein the specific number is selected in accordance with the size of the platform and can be 2-4; when used for the bridge platform, especially for the high-speed rail bridge platform, the number of injection holes can be increased accordingly to 10-20; Drilling at all hole positions using a specific drilling machine to form a plurality of first injection holes; using an integrated drilling and injection machine after the formation of the plurality of first injection holes, simultaneously performing initial injection for the soft soil reinforcement layer beneath the platform through each of the plurality of first injection holes using a segmented drilling and injection method, so that the platform is smoothly and slowly lifted to the allowable deviation range; controlling the lifting and leveling elevation of the platform: setting the relative reference elevation line according to the lifting standard, monitoring the elevation according to the relative reference elevation line, and performing real-time monitoring using a high-precision laser leveling and leveling instrument, wherein the lifting standard has a deviation from the required lifting height of ±10mm; After the platform has become stable, all integrated drilling and injection machines continue to drill down to the bottom of the pile foundation, after which several second injection holes are formed; After forming the plurality of second injection holes, using an integrated drilling and grouting machine to simultaneously perform a second injection for the pile head support layer through the plurality of second injection holes, respectively, using a segmented drilling and grouting method, until the pile head support layer forms a composite foundation to support the pile foundation; Observing the verticality of frame columns or piers of factory buildings: During the platform lifting, leveling, and strengthening process, a precision theodolite is used to observe the verticality of frame columns or piers in real time from two directions to avoid the occurrence of a tilt phenomenon.

[0021] Preferably, the segmented injection used for the initial injection comprises a first injection segment, a second injection segment, a third injection segment, and a fourth injection segment, wherein the first injection segment has a depth of 1-2 m, and wherein the second injection segment, the third injection segment, and the fourth injection segment each have a depth of approximately 1 m. The initial setting time of the liquid mortar used for the initial injection is 10-20 s, and the diffusion radius of the liquid mortar is 1.5-2.0 m. The injection pressure during the initial injection is 0.8-1.5 MPa.

[0022] Preferably, the initial setting time of the liquid mortar used for the second injection is 20-40 s, with the diffusion radius of the liquid mortar being 2.0-3.0 m. The injection pressure for the first injection is 0.6-1.2 MPa.

[0023] The liquid mortar used for the initial injection and the second injection can be any state-of-the-art mortar as long as it meets the initial setting time requirement and has better permeability.

[0024] Preferably, a liquid composite mortar with two components can be used, namely a liquid mortar A and a liquid mortar B, in order to avoid setting of the liquid mortar in the pipe, wherein the two mortars each reach the outlet of the injection pipe from different passages of the drill rod and are pressed into the soil body in the environment at the outlet, and wherein the mortars have a chemical reaction after being brought together in the soil body and complete the initial setting in a short period of time.

[0025] One of the following recipes of the liquid mortar is available: the liquid mortar A is formed by the raw materials with the following parts by weight: 70-90 parts of metal oxide and / or metal hydroxide, 0.5-1.2 parts of the bond retarder, 0.5-0.7 parts of the water reducing agent, 0.7-1.5 parts of the acid-base buffer agent, 3-5 parts of the bond stabilizer and 0.5-1.5 parts of the bond surfactant.The metal oxide may be a combination of any two of magnesium oxide, aluminum oxide, and magnesium phosphate; the composite retarder is at least two of urea, borax, and sodium tripolyphosphate; the water reducing agent may be a polycarboxylic acid water reducing agent or a naphthalene water reducing agent; the acid-base buffering agent is magnesium carbonate or potassium hydroxide; the composite stabilizer is at least two of hydroxymethylcellulose, n-alkyl cetyl alcohol, starch ether, and cellulose ether; the composite surfactant is at least two of alkyl polyoxyethylene ether, benzylphenol polyoxyethylene ether, and alkyl sulfonate.If two or more than two different materials are to be used in a above separate component, they can be prepared according to the order of magnitude, the two settings are mainly to prevent one of them from failing, so that the whole effect of the liquid composite mortar is made more stable.

[0026] Liquid mortar B is made from raw materials with the following weight ratios: 30-40 parts of phosphate and 0.2-1 parts of defoamer. The phosphate can be diammonium hydrogen phosphate or potassium dihydrogen phosphate; the defoamer can be an organic silicone defoamer or a polyether defoamer.

[0027] The liquid mortar A and the liquid mortar B are each mixed and stirred with water at a weight ratio of 100:40-50 to form a liquid mortar, whereby the liquid mortar is pressed into the injection pipe through different pipes and merged at the outlet, and reacts and hardens in the soil body.

[0028] The different initial setting time of the liquid composite mortar is mainly realized by adjusting the specific gravity of the retarder.

[0029] The solution of the present application aims to provide a sinking, strengthening, lifting, and leveling technology for the pile foundation of the building in view of the uneven subsidence of the platform-equipped pile foundation of the existing building. The construction is carried out with a strengthening and lifting method, in particular, the novel technologies and processes such as "platform lifting and leveling" and "pile tip support layer strengthening", etc.In summary, an enlarged composite foundation beam is formed at the bottom of the platform and the strength of the pile tip support layer is improved, so that the load of the upper part is evenly transferred to the support layer; with this solution, the goal of lowering and lifting and leveling the pile foundation platform in industrial factory buildings or bridges is successfully achieved to meet the requirements of the foundation bearing capacity and the design settlement deviation range.

[0030] It should be noted that prior art reinforcement by mortar injection involves a long initial setting time. This is because, after mortar injection, the soil body at the bottom and in the vicinity of the platform and pile foundation softens, causing the platform and pile foundation to subside more rapidly before the injected liquid mortar sets. The technical solution of the present invention effectively prevents platform subsidence during the injection process thanks to the rapid setting properties of the injected liquid mortar and improved permeability.When the platform is raised during the initial injection of mortar, as the liquid mortar, which sets quickly, is continuously injected into the soil layer, the soil body in the surrounding area is pressed, with the course of the continuous injection and setting of the liquid mortar, a lifting of the platform is realized.

[0031] The solution of the present application is realized by the following technical solution: 1. Platform lifting and leveling: First, compaction injection and reinforcement are performed for the soft soil layer below the pile foundation platform. By filling and compacting the liquid mortar, the density and strength of the soft soil layer are improved to increase the gripping force of the soil layer around the piles. Then, the injection pressure is appropriately increased to form an upward reaction force. Subsequently, the pile foundation platform is evenly and slowly raised to the reliable deviation range. 2.Grouting and reinforcement of the pile head support layer: after lifting and leveling the platform, a soft intermediate layer exists between the pile head and the pile head support layer. After the composite foundation of the platform has hardened and formed strength, drilling continues down to the pile head support layer. Grouting and reinforcement of the pile head support layer are carried out to prevent further subsidence of the pile foundation; this achieves the goal of lifting, leveling, and stabilizing the foundation.

[0032] The solution of the present application is realized through the following steps: 1. Using a reinforced concrete detector, the distribution situation of the platform's steel bars is mainly detected. When opening the holes, the steel bars are avoided to prevent damage to the steel bars during the opening of the holes; 2. On both sides of the pile foundation, the holes (2-4 hole positions) are symmetrically provided. The holes are opened using a specific drilling machine, which can be a water drill, and the hole diameter is 42 mm; 3. After opening the holes, an integrated drilling and injection machine is used to drill and inject mortar for the soft soil layer below the platform, so that the platform is raised evenly and slowly to the reliable deviation range; 4.After the platform has become stable, drilling continues downwards to the inside of the pile tip, for the pile tip support layer, grouting and reinforcement are carried out in order to improve the bearing capacity of the pile tip support layer.

[0033] In the entire construction method of the solution according to the present application, a layered forward grouting with integrated drilling and grouting is used to realize reinforcement and lifting. The reinforcement depth increases layer by layer downward. In the first injection segment, the depth is 1.0-2.0 m, in this segment, a higher pressure is used to lift and level the platform; in the second to fourth injection segments, the depth is each about 1.0 m, in these segments, the soft soil layer around the piles is mainly reinforced to stabilize the platform and increase the grip force of the soil layer around the piles for the pile foundation.Finally, the machine drills into the pile head support layer to inject mortar and reinforce the soft interlayer between the pile head and the support layer, thus improving the bearing capacity of the pile head support layer. After the completion of the first injection segment, layered drilling and injection are continued, descending in segments to complete the reinforcement, lifting, and leveling of the entire pile foundation. In the solution of the present application, the hole positions are symmetrical, and drilling and injection are performed simultaneously to avoid uneven injection force during compression and the resulting deviation of the pile foundation.

[0034] In the solution of the present application, the hole diameter of the drilling is 42 mm, the small hole diameter brings little damage which can be easily restored, and the construction work area is small, thus not affecting the normal operation, so as to improve the bearing capacity of the foundation and the dual effect of lifting and leveling.

[0035] It should be noted that relational terms such as "first," "second," etc., in the description only serve to distinguish one object or act from another, and do not necessarily require or imply that such an actual relationship or sequence exists between the objects or acts. Furthermore, the terms "comprising," "having," or other variations cover non-exclusive having, so that a process, method, object, or device comprising a series of elements includes both such elements and other elements not clearly listed or innate to that process, method, object, or device. If no further restrictions apply, a process characterized by the phrase "comprising a..."' does not exclude the possibility that other identical elements may exist in a process, procedure, object or device comprising that element.

[0036] The detailed embodiments are merely illustrative of the present invention, rather than limiting the present invention. Those skilled in the art, after reading this specification, can modify the present embodiment as desired without creative input. However, the modification will be protected by patent law if it falls within the scope of the claims of the present invention.

Claims

[1] Structure for lowering, strengthening, lifting and leveling the pile foundation platform structure, comprising a platform and a plurality of pile foundations firmly connected to the base of the platform; characterized bythat the structure further comprises: a soft soil reinforcement layer below the platform, wherein the platform is located above the soft soil reinforcement layer below the platform; and wherein a plurality of first injection holes are provided on the soft soil reinforcement layer below the platform, and wherein the first injection holes are connected to the outside through the platform; and wherein the first injection holes are used to perform an initial injection for the interior of the soft soil reinforcement layer below the platform to complete the reinforcement for the soft soil reinforcement layer below the platform, and wherein an upward reaction force is generated by means of the injection pressure to slowly raise the platform to the allowable deviation range;a pile-head support layer located below the soft soil reinforcement layer below the platform, wherein a plurality of second injection holes are provided on the pile-head support layer, and wherein the second injection holes are connected to the exterior through the platform and the soft soil reinforcement layer below the platform; and wherein the second injection holes are used to perform a second injection for the interior of the pile-head support layer to form a composite foundation for supporting the pile foundation. [2] Structure for lowering, strengthening, lifting and leveling the pile foundation platform structure according to claim 1, characterized by that the plurality of first injection holes and the plurality of second injection holes are each arranged uniformly symmetrically. [3] Structure for lowering, strengthening, lifting and leveling the pile foundation platform structure according to claim 2, characterized by that the hole diameter of the first injection holes and the second injection holes is 42 mm each. [4] Structure for lowering, strengthening, lifting and leveling the pile foundation platform structure according to claim 1, characterized by that the liquid mortar used for the first injection and the second injection is a liquid mortar with two components, wherein the liquid mortar with different components is pressed and combined into the soil body at the outlet of the injection pipe and reacts and sets, and wherein the initial setting time is 5-60 s. [5] A method of constructing a structure for lowering, strengthening, lifting and leveling the pile foundation platform structure according to any one of claims 1 to 4, characterized bythat the method comprises the following steps: determining the hole positions and the number of injection holes; wherein the hole positions are provided on the two sides of the pile foundation and are distributed symmetrically; and wherein the number of injection holes is more than 1; respectively drilling at all hole positions using a drilling machine to form a plurality of first injection holes; respectively using an integrated drilling and injection machine after the formation of the plurality of first injection holes to simultaneously perform an initial injection for the soft soil reinforcement layer below the platform through the plurality of first injection holes respectively using a segmented drilling and injection method, so that the platform is evenly slowly raised to the allowable deviation range;After the platform has become stable, each integrated drilling and injection machine further drills down to the bottom of the pile foundation, after which a plurality of second injection holes are formed; after the formation of the plurality of second injection holes, each integrated drilling and injection machine simultaneously uses a segmented drilling and injection method to perform a second injection for the pile head support layer through the plurality of second injection holes, until the pile head support layer forms a U-shaped composite foundation to support the pile foundation. [6] A method of constructing a structure for lowering, strengthening, lifting and leveling the pile foundation platform structure according to claim 5, characterized bythat the segmented injection used for the initial injection comprises a first injection segment, a second injection segment, a third injection segment and a fourth injection segment, wherein the first injection segment has a depth of 2 m, and wherein the second injection segment, the third injection segment and the fourth injection segment each have a depth of 1 m. [7] A method of constructing a structure for lowering, strengthening, lifting and leveling the pile foundation platform structure according to claim 6, characterized by that the initial setting time of the liquid composite injection mortar used for the initial injection is 10-20 s, with the diffusion radius of the liquid mortar being 1.5-2.0 m. [8] A method of constructing a structure for lowering, strengthening, lifting and leveling the pile foundation platform structure according to claim 7, characterized bythat the injection pressure during the first injection is 0.8-1.5 MPa. [9] A method of constructing a structure for lowering, strengthening, lifting and leveling the pile foundation platform structure according to claim 5, characterized by that the initial setting time of the liquid composite injection mortar used for the second injection is 20-40 s, with the diffusion radius of the liquid mortar being 2.0-3.0 m. [10] A method of constructing a structure for lowering, strengthening, lifting and leveling the pile foundation platform structure according to claim 9, characterized by that the injection pressure during the second injection is 0.6-1.2 MPa.

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