Layered moistening method for collapsible loess stratum

Abstract

The present application belongs to the technical field of civil engineering, and discloses a layered moistening method for collapsible loess stratum, which comprises the following steps: arranging a flower pipe in a drill hole in the collapsible loess stratum; filling sand particles into the flower pipe and arranging a water-resisting layer when the sand particles are filled to a preset position to obtain a sand well, wherein the sand well comprises a plurality of water-resisting layers, and the plurality of water-resisting layers divide the sand well into a plurality of water injection parts; determining a moistening area of each water injection part, and determining the natural water content and volume of the soil in the moistening area; determining the total water injection amount of each water injection part according to the target water content, the natural water content and the volume; inserting a water injection pipe into each water injection part, and injecting water into the corresponding water injection part through the water injection pipe at a preset water injection rate until the total water injection amount of the water injection part is reached. The present application can realize uniform and controllable moistening of different depths of loess stratum by means of the sand well, the multi-water-resisting layer partition, the accurate calculation of the water injection amount of each layer and the control of the water injection rate.

Description

Technical Field

[0001] This invention belongs to the field of civil engineering technology, and specifically discloses a method for layered moistening of collapsible loess strata. Background Technology

[0002] Collapsible loess is a special type of soil that undergoes significant deformation until it stabilizes under certain pressure and full immersion in water. When undisturbed, collapsible loess generally exhibits high strength and low compressibility. However, upon immersion in water, its structure rapidly deteriorates, its strength decreases, and its compressibility increases, resulting in pronounced collapsibility and subsequent additional settlement, posing a serious threat to the safety and stability of structures. Therefore, when undertaking engineering construction in collapsible loess areas, the characteristics of collapsible loess should be fully considered, and humidification measures should be implemented for foundation treatment to ensure the safety and stability of the project.

[0003] For moistening collapsible loess, commonly used engineering methods include pre-soaking and water injection. Pre-soaking is suitable for sites with thick layers of collapsible loess and significant self-weight subsidence. However, this method requires a large amount of water and has a long construction period. Traditional water injection methods result in uneven water distribution, leading to some areas experiencing greater subsidence while others experience less. This uneven subsidence can introduce additional stress and deformation into the engineering structure. Summary of the Invention

[0004] The purpose of this invention is to provide a layered humidification method for collapsible loess strata, so as to solve the technical problem of uneven water injection in existing humidification methods, which leads to additional stress and deformation of engineering structures.

[0005] This invention provides a method for stratified moistening of collapsible loess strata, comprising:

[0006] Step 1: Install perforated pipes in the boreholes of collapsible loess strata;

[0007] Step 2: Fill the flower tube with sand and set a water-proof layer when it is filled to a preset position to obtain a sand well; the sand well includes multiple water-proof layers, which divide the sand well into multiple water injection sections;

[0008] Step 3: Determine the intended humidification area for each water injection section, and determine the natural moisture content and volume of the soil within the intended humidification area. Based on the target moisture content, the natural moisture content, and the volume, determine the total water injection volume for each water injection section.

[0009] Step 4: Insert a water injection pipe into each water injection section and inject water into the corresponding water injection section through the water injection pipe at a preset water injection rate until the total water volume of the water injection section is reached.

[0010] Preferably, the total water injection volume for each injection section is determined based on the target moisture content, the natural moisture content, and the volume, specifically as follows:

[0011] The mass of the soil is determined based on the volume and average density of the soil within the intended humidification area of ​​each water injection section;

[0012] The water shortage is determined based on the difference between the target moisture content and the natural moisture content;

[0013] Determine the water loss coefficient, and determine the total water injection volume for each injection unit based on the product of the mass, the water shortage, and the water loss coefficient.

[0014] Preferably, the water loss coefficient is 1.05 to 1.15.

[0015] Preferably, after step 4, the method further includes:

[0016] Step 5: After water injection is completed, cement slurry is injected into the corresponding water injection section using the water injection pipe.

[0017] Preferably, the water injection pipe has a water injection hole on the pipe body into which it is inserted.

[0018] Preferably, the outer wall of the water injection pipe is covered with a geotextile filter.

[0019] Preferably, the waterproof layer is made of clay.

[0020] Preferably, multiple water supply branch pipes are arranged around the outer wall of the sand well, and each water supply branch pipe is arranged horizontally.

[0021] Preferably, the lengths of adjacent water supply branch pipes are different.

[0022] The layered wetting method for collapsible loess strata of the present invention has the following advantages compared with the prior art:

[0023] This invention utilizes multiple impermeable layers to divide sand wells into independent water injection sections, avoiding the problem of rapid vertical water flow during traditional whole-well water injection, and achieving independent and uniform water injection into loess strata at different depths. The method of this invention can flexibly adjust the water injection volume and rate of each injection section according to the collapsibility level of loess at different depths, adapting to complex loess strata with uneven thickness and significant differences in collapsibility distribution along depth, avoiding ineffective water injection waste. Simultaneously, this invention determines the water injection volume of a single injection section through quantitative calculations of natural water content, soil volume, and target water content, significantly reducing the deviation in water content after wetting of each soil layer. Attached Figure Description

[0024] Figure 1 This is a flowchart of a method for stratifying and moisturizing collapsible loess strata according to an embodiment of the present invention.

[0025] Figure 2 This is a schematic diagram of the system corresponding to the layered humidification method for collapsible loess strata in an embodiment of the present invention.

[0026] In the diagram: 1 is a sand well; 2 is a waterproof layer; 3 is a water injection pipe; 4 is a water supply branch pipe; 5 is a main pipe; and 6 is a control valve. Detailed Implementation

[0027] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0028] This invention provides a method for stratified moistening of collapsible loess strata, such as... Figure 1 and Figure 2 As shown, it includes:

[0029] Step 1: Install perforated pipes in the boreholes of collapsible loess strata.

[0030] Step 2: Fill the pipe with sand and set a water-proof layer 2 when it is filled to a preset position to obtain a sand well; the sand well in this embodiment of the invention includes multiple water-proof layers 2, which divide the sand well 1 into multiple water injection sections.

[0031] Step 3: Determine the intended humidification area for each water injection section, and determine the natural moisture content and volume of the soil within the intended humidification area. Based on the target moisture content, natural moisture content, and volume, determine the total water injection volume for each water injection section.

[0032] Step 4: Insert water injection pipe 3 into each water injection section, and inject water into the corresponding water injection section through water injection pipe 3 at a preset water injection rate until the total water volume of the water injection section is reached.

[0033] In this embodiment of the invention, multiple water injection pipes 3 can be connected and controlled by the same main pipe 5 and multiple control valves 6.

[0034] This invention utilizes multiple impermeable layers 2 to divide the sand well 1 into independent water injection sections, avoiding the problem of rapid vertical water flow during traditional whole-well water injection, and achieving independent and uniform water injection into loess strata at different depths. The method of this invention can flexibly adjust the water injection volume and rate of each injection section according to the collapsibility level of loess at different depths, adapting to complex loess strata with uneven thickness and significant differences in collapsibility distribution along depth, avoiding ineffective water injection waste. Simultaneously, this invention determines the water injection volume of a single injection section through quantitative calculations of natural water content, soil volume, and target water content, significantly reducing the deviation in water content after wetting of each loess layer.

[0035] To achieve precise water injection control, thereby reducing water consumption while ensuring humidification effect, the total water injection volume for each injection section is determined in this embodiment of the invention based on the target moisture content, natural moisture content, and volume. Specifically, the total water injection volume is determined based on the volume of the soil within the intended humidification area of ​​each injection section. and average density Determine the quality of the soil; based on the target moisture content With natural water content The difference determines the amount of water shortage; the water loss coefficient is determined. And based on quality, water shortage and water loss coefficient The product determines the total water injection volume of each injection unit. Specifically, as shown in formula (1):

[0036] (1)

[0037] For example, the water loss coefficient is 1.05 to 1.15.

[0038] To improve the uniformity of water injection, the water injection pipe 3 of this embodiment is inserted into the lower middle part of the water injection section, and the water injection pipe 3 is provided with a water injection hole on the pipe body into the water injection section, so that water can flow out simultaneously from the outlet of the water injection pipe 3 and the water injection hole on the pipe body.

[0039] To prevent sand particles in the sand well 1 from clogging the water injection holes on the water injection pipe 3, this embodiment of the invention has a geotextile filter screen wrapped around the outer wall of the water injection pipe 3.

[0040] In this embodiment of the invention, clay is used to prepare the waterproof layer 2. The compacted clay has an extremely low permeability coefficient, which can effectively block the crossflow and infiltration of water between the sand wells 1, realize the isolation of water injection sections at different depths in the layered water injection process, and prevent the upper layer water from infiltrating prematurely and interfering with the treatment effect of the lower layer of subsidence.

[0041] To further improve the uniformity of humidification in collapsible loess strata, this embodiment of the invention provides multiple water supply branch pipes 4 arranged around the outer wall of the sand well 1, with each branch pipe 4 horizontally positioned. Preferably, adjacent water supply branch pipes 4 have different lengths. For example, the length of one water supply branch pipe 4 is 1 / 3 of the length from the well wall of the sand well 1 to the outer boundary of the area to be humidified; the length of the adjacent water supply branch pipe 4 is 2 / 3 of the length from the well wall of the sand well 1 to the outer boundary of the area to be humidified. By using two different lengths of water supply branch pipes 4, this invention ensures uniform water supply to the entire soil mass from the well wall of the sand well 1 to the outer boundary of the area to be humidified, avoiding the problem of uneven wetting and drying, where the area near the well is overly wet and the area further from the well is under-watered. Simultaneously, the horizontally arranged pipelines reduce head loss during water supply and are adaptable to the soil humidification and consolidation conditions around the sand well 1, significantly improving the uniformity of soil moisture content throughout the entire area to be humidified.

[0042] In this embodiment of the invention, after water injection and humidification, a moisture content test is required. Once the moisture content meets the standard and the soil is stable against collapsibility, to prevent the borehole from becoming a seepage channel, cement grout is injected into the corresponding water injection section using water injection pipe 3. Water injection pipe 3 also serves as a grouting pipe, resulting in water and energy savings and significant environmental benefits. Post-grouting monitoring is also required for a certain period. Regular checks of soil moisture content and collapsibility are necessary to ensure the stability and safety of the engineering structure. This invention can lay the foundation for compaction, compaction, and composite foundation treatment of collapsible loess strata.

[0043] The above descriptions are merely a few embodiments of the present invention and are not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any modifications or alterations made by those skilled in the art without departing from the scope of the technical solution of the present invention using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for layered moistening of collapsible loess strata, characterized in that, include: Step 1: Install perforated pipes in the boreholes of collapsible loess strata; Step 2: Fill the flower tube with sand and set a water-proof layer when it is filled to a preset position to obtain a sand well; the sand well includes multiple water-proof layers, which divide the sand well into multiple water injection sections; Step 3: Determine the intended humidification area for each water injection section, and determine the natural moisture content and volume of the soil within the intended humidification area. Based on the target moisture content, the natural moisture content, and the volume, determine the total water injection volume for each water injection section. Step 4: Insert a water injection pipe into each water injection section and inject water into the corresponding water injection section through the water injection pipe at a preset water injection rate until the total water volume of the water injection section is reached.

2. The method for layered moistening of collapsible loess strata according to claim 1, characterized in that, The total water injection volume for each injection section is determined based on the target moisture content, the natural moisture content, and the volume, specifically as follows: The mass of the soil is determined based on the volume and average density of the soil within the intended humidification area of ​​each water injection section; The water shortage is determined based on the difference between the target moisture content and the natural moisture content; Determine the water loss coefficient, and determine the total water injection volume for each injection unit based on the product of the mass, the water shortage, and the water loss coefficient.

3. The method for layered moistening of collapsible loess strata according to claim 2, characterized in that, The water loss coefficient is 1.05~1.

15.

4. The method for layered moistening of collapsible loess strata according to claim 1, characterized in that, Following step 4, the following is also included: Step 5: After water injection is completed, cement slurry is injected into the corresponding water injection section using the water injection pipe.

5. The method for layered moistening of collapsible loess strata according to claim 1, characterized in that, The water injection pipe is inserted into the water injection section and has a water injection hole.

6. The method for layered moistening of collapsible loess strata according to claim 5, characterized in that, The outer wall of the water injection pipe is covered with a geotextile filter.

7. The method for layered moistening of collapsible loess strata according to claim 1, characterized in that, The waterproof layer is made of clay.

8. The method for layered moistening of collapsible loess strata according to claim 1, characterized in that, Multiple water supply branch pipes are installed around the outer wall of the sand well, and each water supply branch pipe is installed horizontally.

9. The method for layered moistening of collapsible loess strata according to claim 8, characterized in that, The lengths of adjacent water supply branch pipes are different.

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