CN116537159A - Pipeline reinforcement anti-sedimentation method adjacent to foundation pit - Google Patents

Abstract

The invention discloses a pipeline reinforcement and sedimentation prevention method adjacent to a foundation pit, wherein a side, close to the foundation pit, of a pipeline is reinforced by adopting a back-type grouting method, a plurality of reinforcement supports are formed by grouting reinforcement from the top of a pipeline of a section to be reinforced, and the depth from the ground surface to the bottom of a reinforcement area is not lower than the depth of the foundation pit. The back grouting method is reinforced by a back grouting method of a grouting pipeline, and grout is injected into a stratum in the modes of extrusion, penetration and splitting, so that the strength and elastic deformation modulus of soil are improved. Grouting adopts the mode of adopting sodium silicate and grout to consolidate the soil body below the pipeline, can effectively reduce the pipeline subsidence, guarantees foundation ditch construction smoothly simultaneously, and is effectual, and the influence is little, with low costs. The invention solves the problem that the pipeline is easy to subside in the construction process of the newly-built foundation pit when the newly-built foundation pit is adjacent to the pipeline.

Description

Pipeline reinforcement and anti-subsidence method near foundation pit

technical field

The invention relates to the technical field of building construction, in particular to a method for reinforcing and preventing settlement of pipelines adjacent to foundation pits.

Background technique

At present, construction in urban areas often faces the situation that the new foundation pit is adjacent to the pipeline. During the excavation of a new foundation pit, the pipeline may often settle, and if the settlement is too large, it will easily cause damage to the pipeline.

The information disclosed in this Background section is only for enhancing the understanding of the general background of the present invention and should not be taken as an acknowledgment or any form of suggestion that the information constitutes the prior art that is already known to those skilled in the art.

Contents of the invention

In order to overcome the defects of the existing technology, a method for strengthening and preventing settlement of pipelines adjacent to foundation pits is provided to solve the problem that pipelines are prone to subsidence during the construction process of new foundation pits adjacent to pipelines.

In order to achieve the above purpose, a pipeline reinforcement anti-settlement method near a foundation pit is provided, which includes the following steps:

Determine the position of the section to be reinforced near the foundation pit of the pipeline;

Find out the physical and mechanical property indicators such as the distribution range, water content, particle gradation of soil, groundwater and porosity of the soil layer where the section to be reinforced is located;

Grouting and consolidating in the soil below the section to be reinforced to form a plurality of reinforcement supports, the upper part of the reinforcement supports covers the section to be reinforced, and the covering soil above the reinforcement supports The thickness is greater than 2m. The grout for grouting includes cement, water glass and water. The water-cement ratio of the grout is 1:1, and the mass ratio of the water to the water glass is 4:1. When forming the reinforced support body, the soil layer where the section to be reinforced is located is divided into multiple grouting sections, and each grouting section is grouted from top to bottom, and each grouting section is constructed using Grouting is carried out by a retreating grouting method, and the bottom elevation of the reinforced support body is lower than the bottom elevation of the adjacent foundation pit.

Further, a plurality of reinforcing supports are arranged at intervals along the length direction of the section to be reinforced.

Further, the distance between two adjacent reinforcement supports is 2.5m.

Further, during the grouting process, when the soil body of the soil layer is sandy soil, the grouting pressure is 0.2-0.5 MPa.

Further, during the grouting process, when the soil body of the soil layer is cohesive soil, the grouting pressure is 0.2-0.3 MPa.

The beneficial effect of the present invention is that, in the pipeline reinforcement and anti-settlement method near the foundation pit of the present invention, the side of the pipeline close to the foundation pit is reinforced by the backward grouting method, and the grouting reinforcement is started from the top of the pipe in the section to be reinforced to form multiple Reinforce the support body, the depth from the ground surface to the bottom of the reinforced area shall not be lower than the depth of the foundation pit. The retreating grouting method is reinforced by the retreating grouting method of the grouting pipe, and the grout is injected into the formation in the form of extrusion, penetration, and splitting, so as to improve the strength and elastic deformation modulus of the soil. The grouting uses water glass and cement slurry to reinforce the soil below the pipeline, which can effectively reduce the settlement of the pipeline and ensure the smooth construction of the foundation pit. The effect is good, the impact is small, and the cost is low.

Description of drawings

Other characteristics, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

Fig. 1 is a schematic diagram of pipeline reinforcement near a foundation pit according to an embodiment of the present invention.

Detailed ways

The application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain related inventions, rather than to limit the invention. It should also be noted that, for ease of description, only parts related to the invention are shown in the drawings.

It should be noted that, in the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and embodiments.

Referring to Fig. 1, the present invention provides a pipeline reinforcement anti-settlement method near a foundation pit, comprising the following steps:

S1: Determine the position of the section 1 to be reinforced near the foundation pit A of the pipeline.

Determine the length of the section to be reinforced by surveying the position of the section to be reinforced near the foundation pit of the pipeline.

S2: Find out the physical and mechanical property indicators such as the distribution range, water content, particle gradation of soil, groundwater and porosity of the soil layer where the section 1 to be reinforced is located.

Before determining the grouting reinforcement scheme, find out the physical and mechanical properties of the soil such as the distribution range, water content, soil particle gradation, groundwater, and porosity of the soil layer to be reinforced. At the same time, the effective range of grouting, the selection of grouting materials, the initial setting time, the amount and pressure of grouting, the arrangement of grouting holes and the sequence of grouting must be determined through investigation and research.

S3: Grouting and consolidation in the soil below the section to be reinforced 1 to form a plurality of reinforcement supports 2, the upper part of the reinforcement supports 2 is covered on the section 1 to be reinforced, and the thickness of the covering soil above the reinforcement support 2 If it is larger than 2m, the grout for grouting includes cement, water glass and water. The water-cement ratio of the grout is 1:1, and the mass ratio of water to water glass is 4:1. When the grouting is consolidated to form a reinforced support body 2, the The soil layer where the section to be reinforced 1 is located is divided into multiple grouting sections, each grouting section is grouted from top to bottom, and the retreat grouting method is used for grouting during the construction of each grouting section to reinforce the support The bottom elevation of the body 2 is lower than that of the adjacent foundation pit A.

In this embodiment, after the length of the section to be reinforced is confirmed, the number of reinforcement supports may be determined based on the length of the section to be reinforced.

As a preferred embodiment, a plurality of reinforcement supports 2 are arranged at intervals along the length direction of the section 1 to be reinforced. Further, the distance between two adjacent reinforcement supports 2 is 2.5m.

During the grouting process, when the soil body of the soil layer is sandy soil, the grouting pressure is 0.2-0.5MPa.

During the grouting process, when the soil layer is cohesive soil, the grouting pressure is 0.2-0.3MPa.

The grouting process and effective range should be determined according to the different requirements of the project, and must fully meet the purposes of anti-seepage and plugging, improving soil strength and modulus, filling voids and underpinning. The covering soil at the grouting point should be greater than 2m.

The design of the selected grout and its ratio must consider the purpose of grouting, geological conditions, pore size of the foundation soil, and the state of groundwater, and select the best ratio within the scope of meeting the required purpose.

The grout material for grouting treatment of soft soil can be a suspension with cement as the main agent.

The grouting fluid used to improve the strength of the soil can be a suspension with cement as the main agent.

The initial setting time must be determined according to the soil condition of the foundation and the purpose of grouting. In sandy foundation grouting, the initial setting time of the grout generally used is 5 to 20 minutes, and in the splitting grouting of cohesive soil, the general grouting initial setting time is 1 to 2 hours.

The amount of grouting depends on factors such as the nature of the foundation soil and the permeability of the grout. In the process of large-scale grouting construction, it is advisable to carry out experimental grouting on the construction site to determine the amount of grouting. Generally, the grouting rate in cohesive soil is 15-20%.

The grouting pressure mainly depends on the consistency of the grout material, the grouting depth and the properties of the soil layer. Generally, the sandy soil is 0.2-0.5MPa, and the clayey soil is 0.2-0.3MPa.

The layout principle of the grouting hole should be able to make the soil to be reinforced integrated into a whole in plane and depth.

The grouting sequence must be carried out in accordance with the foundation soil conditions, site environment and grouting purpose. Generally, it is carried out by skipping rows and holes at intervals to prevent grouting and improve the strength and restraint of the grout in the grouting holes. For the special case of underground dynamic water flow, the migration effect under dynamic water flow should be considered, and the grout should be injected from the end with high water head.

When grouting, the construction method of the periphery first and then the interior should be adopted. When there are boundary constraints outside the grouting range, the method of grouting from the inside to the outside in sequence can also be used.

When cement slurry is used for grouting, it is advisable to use ordinary Portland cement with a grade of not less than 425.

The raw materials used for grouting and the prepared slurry shall meet the following requirements:

The prepared slurry should be able to solidify within the time required by the design and have a certain strength, and its own impermeability and durability should meet the design requirements.

After solidification, the volume of the slurry should not have a large shrinkage rate, generally less than 3‰.

The prepared slurry does not undergo water separation within one hour.

The steps of grouting construction are as follows:

The deviation of the hole position shall not be greater than 6cm, and the deviation of the verticality shall be less than 1%. When the grouting hole has a design angle, the deviation of the inclination angle shall not be greater than 5°.

Grouting Prepare the grout according to the design requirements, and control the grouting according to the designed grouting pressure, grouting flow rate, grouting volume per meter, pipe lifting speed, and other parameters.

After the grouting is finished, clean the grouting pipe.

The preparatory work before grouting includes inspection of mechanical appliances, instruments, pipelines, grouting materials, water, electricity, etc. and necessary tests.

Operational control and requirements of the intubation process:

Configure the grouting pipe before intubation. Generally, a 1-inch galvanized pipe with a diameter of 1-5m or a steel pipe with a diameter greater than 30mm is used. The grouting pipe used must be checked in advance whether there is any debris in the pipe and whether the thread is intact Whether the plug at the bottom of the grouting pipe is flexible, and whether the rubber on the flower pipe is tight or not.

When using mechanical equipment to drill holes, the diameter of the drill bit should be Φ56 alloy drill bit. After intubation, care should be taken to seal the hole well.

Use a vibrator for intubation and use a dead plug. The depth of the intubation should exceed the design hole depth by 10-20cm. After the depth of the intubation hole is in place, the grouting pipe should be pulled up by 10-20cm immediately to make the plug fall off.

After intubation, the mouth of the nozzle should be sealed to prevent debris from falling into the pipe and blocking the grouting pipe.

Operation control and requirements of grouting process:

The main materials for grouting are cement and water glass, and grouting is performed at the same time with equal proportions of grout. The water-cement ratio is 1:1, and the water: water glass is 4:1.

The grouting flow rate is generally 7-10L/min. For filling type grouting, the flow rate can be appropriately accelerated but should not be greater than 20L/min.

In order to ensure that the grouting section eats grout evenly, the grouting pipe should be pulled up according to the designed grouting amount per meter, and the height of each pull-up is 330mm when the grout is discharged through the end of the grouting pipe, and the grout is discharged through a 50cm long flower pipe When it is 500mm.

During the grouting process, deformation monitoring of the ground surface and nearby buildings (structures) should be carried out.

During the grouting process, when it is found that the grouting pressure suddenly drops and the flow rate suddenly increases, the injection should be stopped immediately to check whether the grout is leaking or running out. When the grouting and running out occur, the following measures should be taken:

a. Stop grouting for plugging;

b. Reduce the pressure, thicken the slurry or use intermittent grouting;

c. Use water glass and cement slurry for alternate grouting to make the injected grout quick-set.

When the grouting is interrupted for a long time or the double-liquid grouting is interrupted, the pump and pipeline should be flushed in time.

When alternate grouting is used, the alternate amount and frequency of grouting should be strictly controlled according to the design.

During the grouting process, the flow rate, pressure and injection volume of adjacent grouting holes should be compared frequently to analyze the problems existing in the grouting and solve them in time.

After the grouting end standard is reached, the double liquid grouting should press water regularly according to the amount of grout in the pipeline. After the grouting is completed, the orifice valve should be closed temporarily, and the pump and pipeline should be flushed in time. After the internal pressure of the hole is released, the grouting pipe should be pulled out. After the grouting of the whole hole, the hole should be sealed with grouting liquid or cement mortar.

During the construction process, do a good job of detailed construction records, analysis and arrangement.

Grouting construction sequence control

The grouting construction should follow the principle of sequential densification. When grouting multiple rows of holes, the principle of rowing at the side first and then the middle row should be followed in order; for curtains composed of multiple rows of holes, it is advisable to perform grouting on the upstream row first, and then on the downstream row; The grouting holes on the top should be grouted in interval jumping or three sequential grouting.

Holes in the same sequence can be constructed at the same time, and holes in different sequences should be carried out in accordance with the specified sequence.

When the foundation of the existing building is reinforced, the construction sequence with large intervals and jumps should be adopted.

(4) Quality control of grouting construction

Inspection methods for reinforcement grouting should be adopted: excavation, drilling, penetrating, standard penetration, load test, settlement observation, sampling strength inspection, etc. Load test should be done for important projects. The contour of the reinforced body can be inspected by the penetrating sounding method, and the strength of the reinforced body should be tested by taking a test block for infinite compression, or it can be evaluated by the penetrating sounding method or the standard penetration method.

The inspection hole shall be sealed with grout or cement slurry.

The pipeline reinforcement and anti-subsidence method near the foundation pit of the present invention adopts a retreating grouting method on the side of the pipeline close to the foundation pit, and starts grouting from the top of the pipe to be reinforced to form a plurality of reinforcement supports, from the surface to the reinforcement. The depth of the bottom of the area shall not be lower than the depth of the foundation pit. The retreating grouting method is reinforced by the retreating grouting method of the grouting pipe, and the grout is injected into the formation in the form of extrusion, penetration, and splitting, so as to improve the strength and elastic deformation modulus of the soil. The grouting uses water glass and cement slurry to reinforce the soil below the pipeline, which can effectively reduce the settlement of the pipeline and ensure the smooth construction of the foundation pit. The effect is good, the impact is small, and the cost is low.

The above description is only a preferred embodiment of the present application and an illustration of the applied technical principle. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to the technical solution formed by the specific combination of the above-mentioned technical features, but should also cover the technical solution formed by the above-mentioned technical features without departing from the inventive concept. Other technical solutions formed by any combination of or equivalent features thereof. For example, a technical solution formed by replacing the above-mentioned features with technical features with similar functions disclosed in (but not limited to) this application.

Claims (5)

1. The pipeline reinforcement sedimentation prevention method adjacent to the foundation pit is characterized by comprising the following steps of:

determining the position of a section of the pipeline adjacent to the foundation pit to be reinforced;

ascertaining physical and mechanical property indexes such as distribution range, water content, grain composition of soil, groundwater and porosity of a soil layer where the section to be reinforced is positioned;

grouting consolidation is performed in soil below the section to be reinforced to form a plurality of reinforced supports, the upper portions of the reinforced supports are coated on the section to be reinforced, the thickness of the covering soil above the reinforced supports is greater than 2m, grouting slurry comprises cement, water glass and water, and the water-cement ratio of the slurry is 1:1, the mass ratio of the water to the water glass is 4:1, when grouting consolidation is carried out to form the reinforced support body, dividing a soil layer where the section to be reinforced is positioned into a plurality of grouting sections, grouting each grouting section from top to bottom, grouting by adopting a back grouting method when constructing each grouting section, and enabling the bottom elevation of the reinforced support body to be lower than the pit bottom elevation of the adjacent foundation pit.

2. The method of claim 1, wherein a plurality of the reinforcing supports are disposed at intervals along the length of the section to be reinforced.

3. A method of reinforcing a pipe against sedimentation adjacent to a foundation pit as set forth in claim 2, wherein the spacing between adjacent ones of the reinforcing supports is 2.5m.

4. The method for reinforcing and preventing sedimentation of a pipe adjacent to a foundation pit according to claim 1, wherein in the grouting process, when the soil body of the soil layer is sandy soil, the grouting pressure is 0.2-0.5 MPa.

5. The method for reinforcing and preventing sedimentation of a pipe adjacent to a foundation pit according to claim 4, wherein in grouting, when the soil body of the soil layer is clay, grouting pressure is 0.2-0.3 MPa.