Ground surface settlement prevention and control method based on mold bag grouting

Abstract

The invention discloses a ground surface settlement prevention and control method based on mold bag grouting. The ground surface settlement prevention and control method comprises the following steps that geological investigation is conducted, and pile positions are arranged; drilling at the pile position to form a pile hole; the method further comprises the following steps that the main grouting pipe and the geotextile bag on the main grouting pipe are placed into the pile hole together, and backfilling is conducted between the pile hole and the main grouting pipe; pressure grouting is conducted in the main grouting pipe, the grout in the main grouting pipe rises gradually, meanwhile, the grout in the main grouting pipe is pressed into the geotextile mold bag through the secondary grouting pipe, and the geotextile mold bag expands gradually in the radial direction and extrudes the surrounding soil body; and grouting is stopped, and after the grout in the main grouting pipe and the soil engineering mold bag is hardened, the main grouting pipe and the soil engineering mold bag jointly form a mold bag pile body. The construction method has the beneficial effects that the grouting pipes are arranged underground, the expandable mold bags are installed at the preset positions of the grouting pipes, after grout is injected, the mold bags expand directionally and evenly extrude the surrounding soil body, and therefore active compaction of the soil body is achieved, and the rigidity and integrity of a foundation are remarkably improved.

Description

Technical Field

[0001] This application belongs to the field of surface construction technology, specifically relating to a surface settlement control method based on geotextile bag grouting, which achieves surface settlement control through grouting reinforcement. Background Technology

[0002] With the continuous development of urban construction, surface settlement is a common problem during the construction of subway tunnels and other projects. This disturbance of the underground soil disrupts the original stress balance, leading to surface settlement. If settlement is not properly controlled, it can endanger the safety of surface buildings, roads, pipelines, and other municipal facilities, causing serious economic losses. Therefore, how to effectively prevent and control surface settlement is a key issue of long-term concern. Currently, the commonly used technologies for preventing and controlling surface settlement mainly fall into two categories: grouting reinforcement and pile foundation reinforcement.

[0003] Traditional grouting technology mainly involves injecting cement grout or chemical grout into the soil through drilling, filling the soil pores to improve soil strength. However, it has the following shortcomings: First, it is difficult to control the diffusion range and flow direction of the grout, often resulting in disorderly grout loss and affecting the reinforcement effect; second, in strata with poor permeability, the grout is difficult to diffuse effectively, limiting the reinforcement effect; third, traditional grouting mainly relies on filling action, with insufficient compression effect on the soil.

[0004] Pile foundation reinforcement technologies, such as precast piles and bored piles, reduce settlement by transferring the load to the deep bearing layer. These technologies are highly reliable, but they also have drawbacks such as high construction costs, long construction periods, and significant environmental disturbance.

[0005] To overcome the shortcomings of traditional grouting methods, geotextile bag grouting technology has been proposed. This method involves delivering a geotextile bag to a predetermined underground location via a grouting pipe, then injecting grout into the bag, causing the grout to expand directionally under the constraint of the bag. Existing geotextile bag grouting is mostly used to form regular pile bodies, prevent grout loss, or perform segmented grouting (such as published patent CN119913890A), which can improve grouting efficiency and reduce costs.

[0006] However, existing methods for using geotextile bags for grouting have limitations. While they can serve to reinforce piles and prevent grout leakage, they fail to fully utilize the squeezing effect on the surrounding soil during the expansion of the geotextile bags, nor do they increase the overall integrity of the soil layer. Furthermore, current technology has not yet proposed a systematic arrangement method to enable the geotextile bags and the squeezed soil between them to work synergistically, thereby constructing a composite foundation with a group-pile effect and overall bearing capacity.

[0007] In summary, there is an urgent need in this field for a new technical solution that can inherit the controllability advantages of geotextile grouting and innovatively make full use of the pile group effect, thereby significantly improving the overall foundation stability and reducing the risk of surface settlement. Summary of the Invention

[0008] The purpose of this application is to address the problems of uncontrollable grout diffusion, limited reinforcement effect, and inadequate utilization of the group pile effect in existing technologies. This application provides a surface settlement control method based on geotextile bag grouting. By laying grouting pipes underground and setting up expansion geotextile bags, the geotextile bags expand during the grouting process and compress the soil, thereby forming a "group pile effect", avoiding uneven settlement and effectively controlling surface settlement.

[0009] The objective of this application is achieved through the following technical solution: A method for controlling surface settlement based on geotextile bag grouting includes the following steps: S1, geological survey and pile location arrangement; S2, drilling holes at the pile locations to form pile holes; and further includes the following steps: S3, placing the main grouting pipe and the geotextile bag attached to the main grouting pipe into the pile hole, and backfilling the space between the pile hole and the main grouting pipe; S4, pressure grouting into the main grouting pipe, the grout in the main grouting pipe gradually rises, and at the same time, the grout in the main grouting pipe is pressed into the geotextile bag through the secondary grouting pipe, the geotextile bag gradually expands radially and squeezes the surrounding soil; S5, stopping grouting, and waiting for the grout in the main grouting pipe and the geotextile bag to harden, the main grouting pipe and the geotextile bag together form a geotextile bag pile.

[0010] Furthermore, in S1, the pile positions of the pile group are arranged; in S4, grouting operations are carried out on all pile positions simultaneously; in S5, all the formwork piles and the compressed soil together form an integral composite foundation.

[0011] Furthermore, in S1, the piles are arranged in a grid pattern with alternating horizontal and vertical axes.

[0012] Furthermore, in S3, at least two sections of geotextile bags are arranged along the upper and lower edges of the main grouting pipe.

[0013] Furthermore, in S3, the geotextile bag includes an inner pressure-bearing permeable layer and an outer impermeable isolation layer; in S4, grout seeps out from the pressure-bearing permeable layer to form a cementing layer between the pressure-bearing permeable layer and the impermeable isolation layer.

[0014] Furthermore, the pressure-bearing permeable layer is a permeable non-woven fabric, and the seepage-proof isolation layer is a tear-resistant nylon fabric.

[0015] Furthermore, in S3, the geotextile bag has a ring-shaped structure.

[0016] Furthermore, in S3, both the upper and lower ends of the geotextile bag are fixed to the main grouting pipe by mechanical clamps.

[0017] Furthermore, in S3, the top of the geotextile bag is connected to the exhaust pipe.

[0018] Furthermore, in S4, the grout is pressurized in stages. In the initial stage, low-pressure grouting is used to allow the geotextile bag to slowly unfold and fit into the soil. Subsequently, the grouting pressure is increased to allow the geotextile bag to fully expand and compress the soil.

[0019] The function achieved by this application is as follows: after drilling, grouting pipes are laid at a predetermined depth underground, and two-section high-strength geotextile bags are set up. After all the grouting pipes and geotextile bags are placed, the grouting pump is turned on to inject grout into the grouting pipes. Through pressure grouting, the geotextile bags are expanded into piles of a predetermined shape. The surrounding soil is squeezed under the expansion of the geotextile bags. While squeezing and densifying the surrounding soil, the numerous piles and the compacted soil together form an integral composite foundation. The group pile effect is used to greatly improve the stiffness and integrity of the foundation and reduce uneven settlement.

[0020] The beneficial effects of this application are: (1) By laying grouting pipes underground and installing expandable mold bags at their predetermined positions, the mold bags expand in a directional manner after the grout is injected, and the surrounding soil is uniformly squeezed, thereby achieving active compaction of the soil and significantly improving the rigidity and integrity of the foundation.

[0021] (2) The geotextile bag structure can effectively constrain the grout, prevent its disorderly diffusion and loss, and improve the utilization rate of grouting. After multiple geotextile bags are arranged in a regular manner, they interact with each other to form a composite foundation structure similar to a pile group, which further enhances the overall deformation resistance and realizes the active prevention and control of surface settlement.

[0022] (3) The construction process of the geotextile bag is simple and highly adaptable, and has good prospects for engineering application.

[0023] The aforementioned main solution and its various further alternatives can be freely combined to form multiple solutions, all of which are solutions that can be adopted and are claimed in this application; furthermore, the (non-conflicting alternatives) can also be freely combined with each other and with other alternatives. Those skilled in the art, after understanding the solution of this application, will realize from the prior art and common general knowledge that there are many combinations, all of which are technical solutions to be protected by this application, and will not be exhaustively listed here. Attached Figure Description

[0024] Figure 1 This is a structural diagram of this application.

[0025] Figure 2 This is a schematic diagram illustrating the effect of the mold bag in this application.

[0026] Figure 3 This is a schematic diagram of the planar layout of the molded bag in this application.

[0027] In the diagram: 1-Ground surface, 2-Main grouting pipe, 3-Mechanical clamp, 4-Secondary grouting pipe, 5-Confined permeable layer, 6-Squeezed soil, 7-Imperible isolation layer, 8-Exhaust pipe, 9-Geotextile bag, 10-Grouting, 11-Pile hole, 12-Geotextile bag influence area. Detailed Implementation

[0028] The following non-limiting embodiments are used to illustrate this application.

[0029] Example 1 refer to Figures 1-3 As shown, a ground settlement control method based on geotextile grouting requires, before implementing this control method, obtaining soil layer distribution, physical and mechanical properties and groundwater level data of the area to be controlled based on the survey report, and carrying out reinforcement design in combination with the superstructure load conditions, allowable settlement and soil characteristics.

[0030] The prevention and control method includes the following steps: S1, geological survey and pile location arrangement, based on the engineering geological survey report, determine the physical and mechanical parameters of the soil and the settlement risk, and design the target depth of the pile hole.

[0031] S2, Drill holes at the pile location to form pile hole 11. The drilling layout is determined based on the location of the larger settlement. The lifting range and lifting height are determined based on the field test. The specific layout is dynamically adjusted according to the test data. Drill holes below the ground surface 1 to the predetermined depth at the designed pile location.

[0032] S3. Place the main grouting pipe 2 and the geotextile formwork bag 9 attached to it into the pile hole 11, and backfill the space between the pile hole 11 and the main grouting pipe 2. After connecting the folded formwork bag to the main grouting pipe and the secondary grouting pipe, place them together into the pile hole, ensuring that the formwork bag reaches the designed position. After installation, backfill the gap between the pile hole and the main grouting pipe with undisturbed soil, and compact it in layers to restore the original stress state of the soil around the hole.

[0033] The main grouting pipe 2 is a steel pipe or a composite material pipe, with several grout outlets along its depth direction on the pipe wall. The geotextile bag 9 includes an inner pressure-bearing permeable layer 5 and an outer impermeable isolation layer 7, which can remain stable during high-pressure grouting. Preferably, the pressure-bearing permeable layer 5 is made of permeable non-woven fabric, and the impermeable isolation layer 7 is made of tear-resistant nylon fabric.

[0034] At least two sections of geotextile formwork bags 9 are arranged along the upper and lower edges of the main grouting pipe 2 to ensure uniform and stable grouting effect. The upper formwork bags are placed 0.5m away from the bottom layer of key structures. The geotextile formwork bags 9 have a loop-like structure, which allows them to be installed on the main grouting pipe 2. The loop shape means that the formwork bag is wrapped around the main grouting pipe 2. Both the upper and lower ends of the geotextile formwork bags 9 are fixed to the main grouting pipe 2 by mechanical clamps 3 to seal the openings at both ends of the geotextile formwork bags 9. In conjunction with rubber sealing rings, the sealing performance is improved.

[0035] The top of the geotextile formwork bag 9 is connected to the exhaust pipe 8. An exhaust pipe is installed outside the formwork bag, which is close to the outer wall of the formwork bag, made of polyethylene material, and fixed with plastic strips to release the air present in the formwork bag during the initial stage of grouting.

[0036] S4, pressure grouting is performed into the main grouting pipe 2. The grout 10 in the main grouting pipe 2 gradually rises. At the same time, the grout 10 in the main grouting pipe 2 is pressed into the geotextile bag 9 through the secondary grouting pipe 4. The geotextile bag 9 gradually expands radially and squeezes the surrounding soil.

[0037] The grouting pump is started, injecting grout into the main grouting pipe 2, which then enters the geotextile formwork 9 and gradually expands. By controlling the grouting sequence and pressure, the grout first enters the deepest part of the formwork, gradually increasing upwards to form segmented reinforcement. After grouting, the formwork, under the pressure of the grout, overcomes the resistance of the surrounding soil and expands radially and uniformly. During the expansion process, the formwork exerts a radial compression effect on the surrounding soil, reducing the void ratio and increasing the soil density, thereby increasing the overall integrity of the foundation.

[0038] The grout 10 is applied using staged pressurization. In the initial stage, low-pressure grouting is used to slowly expand the geotextile bag 9 and allow it to conform to the soil. Subsequently, the grouting pressure is increased to allow the geotextile bag 9 to fully expand and compress the soil. The grout initially uses ordinary single-component cement grout, which provides a slow and controllable grouting process. If the single-component grouting does not provide significant grouting or the pressure build-up is slow, a cement-water glass two-component grout can be used.

[0039] The grout, prepared according to the design ratio, is injected into the formwork bag through a secondary grouting pipe. Under the pressure of the grout, the formwork bag gradually expands, uniformly and radially compressing the surrounding soil, significantly increasing its density. By controlling the grouting pressure and volume, the final expansion diameter and compaction range of the formwork bag can be precisely controlled. A monitoring system, including pressure sensors and flow meters, should be installed during the grouting process to monitor the grouting effect in real time.

[0040] Grout enters the geotextile bag 9, and grout 10 (water and cement) seeps out from the confined permeable layer 5, forming a cementing layer between the confined permeable layer 5 and the impermeable isolation layer 7. This cementing layer is used to form a cementing layer when there is a small amount of grout seepage during the grouting process, thereby enhancing the bonding effect between the geotextile bag and the soil.

[0041] S5, stop grouting, wait for the grout 10 in the main grouting pipe 2 and the geotextile bag 9 to harden, and the main grouting pipe 2 and the geotextile bag 9 together form a high-strength, regularly shaped geotextile bag pile.

[0042] In S1, the specific locations of the pile groups are arranged, and the layout pattern, spacing, row spacing, and target depth of the pile groups are designed. The pile groups are arranged in a grid pattern with alternating horizontal and vertical directions. In S4, grouting is carried out on all pile locations simultaneously. In S5, all the geotextile piles and the compressed soil 6 together form an integral composite foundation.

[0043] Throughout the area to be reinforced, the main grouting pipes 2 are laid out in a rectangular grid pattern, with multiple manhole covers arranged regularly on the plane. After grouting and expansion, the effective ranges of the manhole covers overlap, forming the manhole cover influence zone 12, which together with the soil between the piles forms a composite foundation. The numerous manhole cover piles and the compacted soil between the piles together constitute a unified composite foundation. This composite foundation works synergistically, increasing the stiffness and integrity of the soil layer, effectively dispersing the upper load, and reducing uneven settlement.

[0044] Through the above-described embodiments, this application can fully utilize the constraint and expansion compression effects of the geotextile bags, enabling the soil to achieve active compaction during the grouting process. Multiple geotextile bags work together to form a group pile effect, significantly improving the overall stability and anti-settlement capacity of the foundation, thereby achieving an economical, efficient, and reliable surface settlement prevention effect.

[0045] The foregoing basic examples and their further alternative examples can be freely combined to form multiple embodiments, all of which are embodiments that can be adopted and claimed in this application. In the scheme of this application, each alternative example can be arbitrarily combined with any other basic example and alternative example.

[0046] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A ground surface settlement prevention and control method based on mold bag grouting, comprising the following steps: S1, geological survey and arrangement of pile position; S2, drilling a hole at the pile position to form a pile hole (11); characterized in that Further comprising the following steps: S3, placing a main grouting pipe (2) and a geotechnical mold bag (9) on the main grouting pipe (2) into the pile hole (11) together, and backfilling between the pile hole (11) and the main grouting pipe (2); S4, pressure grouting into the main grouting pipe (2), the slurry (10) in the main grouting pipe (2) gradually rises, at the same time, the slurry (10) in the main grouting pipe (2) is pressed into the geotechnical mold bag (9) through the secondary grouting pipe (4), the geotechnical mold bag (9) gradually expands radially and extrudes the surrounding soil body; S5, stop grouting, and wait for the slurry (10) in the main grouting pipe (2) and the geotechnical mold bag (9) to harden, the main grouting pipe (2) and the geotechnical mold bag (9) form a mold bag pile body together.

2. The method for preventing and controlling ground settlement based on mold-bag grouting according to claim 1, characterized in that: In the S1, the pile positions of group piles are arranged; in the S4, grouting operations are performed on all pile positions at the same time; in the S5, all mold bag pile bodies and extruded soil bodies (6) form an integral composite foundation together.

3. The method for preventing and controlling ground settlement based on mold-bag grouting according to claim 2, characterized in that: In the S1, the group piles are arranged in a grid shape with horizontal and vertical staggered arrangement.

4. The ground settlement prevention and control method based on mold-bag grouting according to claim 1, 2 or 3, characterized in that: In the S3, the geotechnical mold bag (9) is arranged on the main grouting pipe (2) in at least two sections from top to bottom.

5. The method for ground settlement prevention and control based on mold-bag grouting according to claim 1, 2 or 3, characterized in that: In the S3, the geotechnical mold bag (9) comprises an inner pressure-bearing water-permeable layer (5) and an outer anti-seepage isolation layer (7); in the S4, the slurry (10) seeps out from the pressure-bearing water-permeable layer (5), and a cementing layer is formed between the pressure-bearing water-permeable layer (5) and the anti-seepage isolation layer (7).

6. The method for ground settlement prevention and control based on mold-bag grouting according to claim 5, characterized in that: The pressure-bearing water-permeable layer (5) is a water-permeable non-woven fabric, and the anti-seepage isolation layer (7) is a tear-resistant nylon fabric.

7. The method for ground settlement prevention and control based on mold-bag grouting according to claim 1, 2 or 3, characterized in that: In the S3, the geotechnical mold bag (9) has a sleeve ring structure.

8. The method for ground settlement prevention and control based on mold-bag grouting according to claim 7, characterized in that: In the S3, the upper and lower ends of the geotechnical mold bag (9) are fixed on the main grouting pipe (2) by mechanical clamps (3).

9. The method for ground settlement prevention and control based on mold-bag grouting according to claim 1, 2 or 3, characterized in that: In the S3, the top of the geotechnical mold bag (9) is communicated with an exhaust pipe (8).

10. The method for ground settlement prevention and control based on mold-bag grouting according to claim 1, 2 or 3, characterized in that: In the S4, the slurry (10) is subjected to staged pressurization, low-pressure grouting is used in the initial stage to slowly unfold the geotechnical mold bag (9) and make it fit the soil body, and then the grouting pressure is increased to fully expand the geotechnical mold bag (9) and extrude the soil body.

Images