In-situ solidification construction method for pipeline trench free-support excavation in soft soil area

Abstract

The application discloses a kind of soft soil area pipeline trench exempt from support excavation in-situ solidification construction method, comprising the following steps: according to the trench design excavation position of the pipeline to be constructed, determine the in-situ solidification area, and the in-situ solidification area is divided into side wall forming area, base forming area and excavation area;The side wall forming area and base forming area are in-situ mixing and solidification, to form side wall solidification body and base solidification body, and adjust the solidification parameters of excavation area according to the soil body condition of excavation area, so that the excavation area at least meets the construction equipment traffic requirement and soil excavation requirement;After the side wall solidification body and base solidification body reach the design strength, the excavation area is excavated, so that the side wall solidification body forms the trench side wall, and the base solidification body forms the trench base;Pipeline foundation construction is carried out on the trench base, and pipeline laying and trench backfilling are completed, and the construction efficiency is improved by the above construction method.

Description

Technical Field

[0001] This invention relates to the field of building construction technology, and in particular to an in-situ solidification construction method for pipeline trenches in soft soil areas without the need for support during excavation. Background Technology

[0002] In existing technologies, when excavating pipeline trenches in soft soil areas, steel sheet piles are typically used in conjunction with steel pipe supports, along with dewatering and drainage construction. After the trench excavation is completed, separate foundation treatment is required for the trench base. This construction method has several problems: complex construction procedures, long construction period, and high cost; significant deformation of the foundation pit during the excavation process, posing a risk of localized compression deformation and collapse; and the separate implementation of trench excavation and foundation treatment requires secondary construction, further extending the construction period.

[0003] To address the aforementioned issues, some existing solutions employ a construction approach of in-situ solidification before excavation. This involves solidifying the soft soil within the excavation area as a whole, allowing it to gain sufficient self-supporting capacity before excavation. However, this approach, while uniformly solidifying the soil across the entire excavation area, still requires the removal of a significant amount of solidified soil after excavation, resulting in material waste. Other solutions utilize in-situ solidification at the pit bottom combined with external support piles. This involves establishing a support system using support piles and water-stop piles, followed by solidification at the pit bottom. However, this method still relies on traditional support pile systems and fails to achieve support-free construction. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects of the prior art and provide an in-situ solidification construction method for pipeline trench excavation without support in soft soil areas. By dividing the in-situ solidification area into a sidewall formation area, a base formation area, and an excavation area and performing differentiated solidification in each area, the sidewall formation area and the base formation area constitute a continuous solidification area. The solidified body itself forms the support structure and base structure of the trench, thereby achieving supportless excavation, improving construction efficiency, and reducing construction costs.

[0005] To achieve the above objectives, the technical solution adopted in this invention is an in-situ solidification construction method for pipeline trench excavation without support in soft soil areas, comprising the following steps: Step 1: Determine the in-situ curing area based on the trench design and excavation location of the pipeline to be constructed, and divide the in-situ curing area into the sidewall formation area, the base formation area, and the excavation area; Step 2: In-situ mixing and solidification are carried out on the sidewall formation area and the base formation area to form a solidified sidewall body and a solidified base body. The solidification parameters of the excavation area are adjusted according to the soil conditions of the excavation area so that the excavation area at least meets the requirements for the passage of construction equipment and the requirements for soil excavation. Step 3: After the solidified sidewall and solidified base have reached their designed strength, the excavation area is excavated so that the solidified sidewall forms the trench sidewall and the solidified base forms the trench base. Step 4: Construct the pipe foundation on the trench base, and complete the pipe laying and trench backfilling.

[0006] The further improvement of the in-situ curing construction method for unsupported excavation of pipeline trenches in soft soil areas of the present invention is that the sidewall forming area is located on both sides of the excavation area, the base forming area is located below the excavation area, and the sidewall forming area and the base forming area are connected to form a continuous curing area.

[0007] A further improvement of the in-situ curing construction method for unsupported excavation of pipeline trenches in soft soil areas of the present invention is that the cross-section of the continuously cured area is U-shaped, and the sidewall forming area extends obliquely from top to bottom toward the excavation area.

[0008] A further improvement of the in-situ solidification construction method for pipeline trench excavation without support in soft soil areas of the present invention is that, when performing step 1 above, the slope of the sidewall formation area is first determined according to the soil conditions of the in-situ solidification area.

[0009] The further improvement of the in-situ solidification construction method for pipeline trench excavation without support in soft soil areas of the present invention is that, after performing step 1 and before performing step 2, surface interception and drainage treatment is carried out on the in-situ solidification area to form a surface slope towards the outside of the in-situ solidification area, and drainage ditches are excavated around the in-situ solidification area.

[0010] The further improvement of the in-situ curing construction method for pipeline trench excavation without support in soft soil areas of the present invention is that, in step 2, the in-situ curing area is divided into multiple construction sections along the length of the trench, and each construction section is mixed and cured in situ in sequence. The curing areas of adjacent construction sections overlap each other to form a sidewall curing body and a base curing body that are continuously set along the length of the trench.

[0011] A further improvement of the in-situ curing construction method for unsupported excavation of pipeline trenches in soft soil areas of the present invention is that, when performing step 2 above, the boundary area between the sidewall formation area and the base formation area is reinforced and cured.

[0012] A further improvement of the in-situ solidification construction method for unsupported excavation of pipeline trenches in soft soil areas of the present invention is that, when performing step 3 above, the excavation area is excavated in layers.

[0013] The further improvement of the in-situ solidification construction method for pipeline trench excavation without support in soft soil areas of the present invention is that, after performing step 3 and before performing step 4, the bearing capacity of the trench base is tested, and step 4 is performed after the test results meet the design requirements.

[0014] A further improvement of the in-situ solidification construction method for pipeline trench excavation without support in soft soil areas of the present invention is that, when performing step 4 above, after the pipeline is laid, the two sides of the trench are backfilled in layers simultaneously to reduce the displacement caused by uneven stress on the pipeline.

[0015] Compared with the prior art, the advantages of the present invention are: 1. By dividing the in-situ solidification area into a sidewall formation area, a foundation formation area, and an excavation area, and implementing differentiated solidification for each zone, the sidewall formation area is reinforced according to the retaining wall standard, and the foundation formation area is reinforced according to the foundation bearing capacity standard, thus achieving simultaneous foundation treatment. This avoids the construction of a large number of steel sheet pile support systems and the costs of dewatering and drainage in water-rich areas, significantly shortening the construction period and reducing costs.

[0016] 2. By performing low-intensity solidification on the excavation area to meet the requirements for the passage of construction equipment and soil excavation, the normal operation of construction equipment in soft soil areas is guaranteed, while avoiding material waste caused by uniform solidification, thus achieving full and rational utilization of resources. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the partitioning and reinforcement of the in-situ curing area of ​​the present invention.

[0019] Figure 2 This is a schematic diagram of the construction equipment used for in-situ mixing and curing according to the present invention.

[0020] 1. Tracked planetary jet sprayer; 2. Liquid storage container; 3. Sidewall formation zone; 4. Foundation formation zone; 5. Excavation zone. Detailed Implementation

[0021] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0022] The following description, in conjunction with the accompanying drawings and specific embodiments, provides a more detailed explanation of the in-situ solidification construction method for unsupported excavation of pipeline trenches in soft soil areas according to the present invention.

[0023] Please see Figures 1-2 As shown, the in-situ solidification construction method for pipeline trenches in soft soil areas without support excavation includes the following steps: Step 1: Determine the in-situ curing area based on the trench design and excavation location of the pipeline to be constructed, and divide the in-situ curing area into sidewall formation area 3, base formation area 4 and excavation area 5; Step 2: In-situ mixing and solidification are carried out on the side wall forming area 3 and the base forming area 4 to form a solidified side wall body and a solidified base body. The solidification parameters of the excavation area 5 are adjusted according to the soil conditions of the excavation area 5 so that the excavation area 5 at least meets the requirements for the passage of construction equipment and the requirements for soil excavation. Step 3: After the solidified sidewall and the solidified base have reached the design strength, the excavation area 5 is excavated so that the solidified sidewall forms the trench sidewall and the solidified base forms the trench base. Step 4: Construct the pipe foundation on the trench base, and complete the pipe laying and trench backfilling.

[0024] Specifically, when performing step 2 above, a tracked planetary jet 1 is provided for in-situ mixing and solidification. The tracked planetary jet 1 includes a walking mechanism, a mixing arm, and a planetary jet nozzle located at the end of the mixing arm. It is used to inject reinforcement slurry while cutting the soil to mix and reinforce the soil with the reinforcement slurry. The tracked planetary jet 1 is externally connected to a liquid storage container 2, which is equipped with a mixing device. The liquid storage container 2 is used to continuously transport the reinforcement slurry.

[0025] In-situ mixing and solidification are achieved by using a tracked planetary mixer 1. The planetary mixer head cuts the soil while injecting and mixing the reinforcing slurry, ensuring that the reinforcing slurry and soil are fully and evenly mixed. At the same time, the tracked walking mechanism allows the equipment to move freely in soft soil without the need for an additional working platform. The external liquid storage container 2 can continuously supply slurry, avoiding the need for mid-process stoppages for material replenishment, thus ensuring the continuity and high efficiency of the solidification operation.

[0026] Specifically, the curing parameters include at least one of the following: curing agent dosage, stirring depth, number of stirring cycles, and stirring speed.

[0027] Specifically, the solidification parameters of excavation zone 5 are determined based on the soil moisture content, fluidity, and bearing capacity of excavation zone 5. When the soil bearing capacity meets the requirements for the passage of construction equipment, the amount of solidifying agent in excavation zone 5 is reduced or the solidification range is narrowed. When the soil bearing capacity is insufficient, the amount of solidifying agent in excavation zone 5 is increased or the solidification range is expanded.

[0028] By adjusting the curing parameters as needed according to the soil conditions of excavation zone 5, adaptive curing of excavation zone 5 can be achieved, reducing the amount of curing agent used and improving material utilization while meeting construction requirements.

[0029] Specifically, when the bearing capacity of the foundation in the in-situ solidification area cannot meet the passage requirements of the tracked planetary mixer 1, a bearing pad is laid on the walking path of the tracked planetary mixer 1 to improve the stability of the equipment; or a tracked planetary mixer 1 with a floating box structure is used for in-situ mixing and solidification.

[0030] By modifying the structure by setting up load-bearing pads or floating boxes, the stability of construction equipment on soft soil foundations is improved, so that excavation zone 5 does not need to meet the load-bearing structure requirements, which can further reduce the degree of solidification of excavation zone 5 and reduce the consumption of solidification materials.

[0031] Specifically, when performing step 2 above, if there is miscellaneous fill, pond slag or other impurities that affect the uniformity of mixing in the in-situ solidification area, it should be cleaned first before in-situ mixing and solidification is carried out; if there are many impurities in the soil in the in-situ solidification area or the in-situ mixing requirements cannot be met, the soil in the in-situ solidification area should be excavated, impurities removed, and then fully mixed with the reinforcement slurry before being backfilled into the in-situ solidification area.

[0032] By removing impurities that affect the uniformity of mixing or by pre-treating special soil types, the uniformity and molding quality of the solidified soil can be improved.

[0033] Preferably, the sidewall forming area 3 is located on both sides of the excavation area 5, the base forming area 4 is located below the excavation area 5, and the sidewall forming area 3 and the base forming area 4 are connected to form a continuous solidification area.

[0034] Specifically, the sidewall solidified body and the base solidified body are interconnected to form a continuous solidified structure. The sidewall solidified body is used to bear the soil pressure on the trench sidewall, and the base solidified body is used to improve the bearing capacity of the trench base. Together, they form a stable support system during the trench excavation process, so that the trench can remain stable without the need to install steel sheet piles, steel internal bracing or other temporary support structures during the excavation process.

[0035] Preferably, the cross-section of the continuously solidified area is U-shaped, and the sidewall forming area 3 extends obliquely from top to bottom toward the excavation area 5.

[0036] By setting the continuous curing area as a U-shaped structure, the sidewall curing body and the base curing body form a continuous support structure, and the inclined sidewall curing body is used to improve the constraint capacity on the outer soil, thereby improving the sidewall stability during trench excavation.

[0037] Preferably, when performing step 1 above, the slope of the sidewall forming zone 3 is first determined based on the soil conditions of the in-situ solidification area.

[0038] Specifically, in step 1, the soil in and around the in-situ solidification area is surveyed and sampled to obtain soil conditions, and the corresponding soil mechanics parameters are determined based on these conditions. The solidified sidewall and the solidified base are used as retaining structures to establish soil mechanics calculation models. Stability analysis is performed based on the lateral earth pressure exerted on the retaining structure by the soil outside the trench and the construction load. Based on the analysis results, the design slope, design solidification range, and design solidification depth of the sidewall formation area 3, as well as the design solidification range and design solidification depth of the base formation area 4, are determined.

[0039] By combining soil conditions and stress analysis, the design parameters of the sidewall formation zone 3 and the base formation zone 4 are determined, so that the solidified structure matches the actual stress requirements, improves the stability during trench excavation, and avoids material waste caused by over-solidification.

[0040] Specifically, when performing step 2 above, the actual curing range and the actual curing depth are both greater than the design values.

[0041] By ensuring that the actual curing range and depth are greater than the design values, a margin is reserved for construction deviations, ensuring that the formed cured body meets the design requirements and improving the reliability of the cured structure.

[0042] The selection of pit wall slope under unsupported foundation conditions is shown in the table below: Specifically, in step 2, lines are laid out on the ground according to the inclined boundary of the sidewall forming area 3 to determine the projection positions of the top and bottom boundary lines of the sidewall forming area 3 on the ground. During construction, the planetary nozzle of the tracked planetary grouting machine 1 is controlled to penetrate underground to the design depth from the position corresponding to the bottom boundary line. Then, it is lifted while grouting, mixing and lifting along the inclined direction of the sidewall forming area 3 until it is lifted to the ground from the position corresponding to the top boundary line to form a solidified sidewall with a design slope. The lifting trajectory of the planetary nozzle is consistent with the design inclined slope of the sidewall forming area 3.

[0043] By adopting a mixing and lifting trajectory that matches the design slope of the sidewall forming zone 3, the inclined sidewall solidified body can be formed in one step, avoiding subsequent adjustments and improving construction efficiency and forming quality.

[0044] Specifically, depth markings are set on the mixing arms of the tracked planetary agitator 1 according to the designed curing depth to control the in-situ mixing depth of each zone.

[0045] By setting depth markers, accurate control of in-situ mixing depth can be achieved, improving the consistency of curing depth and curing quality in each zone.

[0046] Preferably, after performing step 1 and before performing step 2, surface interception and drainage treatment is carried out on the in-situ solidified area to form a surface slope towards the outside of the in-situ solidified area, and drainage ditches are excavated around the in-situ solidified area.

[0047] Specifically, after performing step 1, the soil around the in-situ solidification area is excavated to make the surface elevation of the in-situ solidification area at least 300mm higher than the surrounding surface; then, a drainage ditch is excavated along the perimeter of the in-situ solidification area to allow surface water to flow into the drainage ditch and be discharged from the construction area.

[0048] By raising the surface elevation of the in-situ solidification area higher than the surrounding surface and excavating drainage ditches along the perimeter, surface water is allowed to naturally flow into the drainage ditches and drain out, preventing surface water from flowing into the solidification area and further soaking the soft soil, thus ensuring the quality of the solidification construction.

[0049] Preferably, when performing step 2, the in-situ curing area is divided into multiple construction sections along the length of the trench, and each construction section is mixed and cured in situ in sequence. The curing areas of adjacent construction sections overlap each other to form a sidewall curing body and a base curing body that are continuously set along the length of the trench.

[0050] By constructing in sections and overlapping adjacent sections, a continuous curing structure is formed along the length of the trench, improving the integrity of the sidewall curing body and the base curing body.

[0051] Specifically, the overlap length between adjacent construction sections shall not be less than 20cm.

[0052] Preferably, during step 2 above, the boundary area between the sidewall forming area 3 and the base forming area 4 is reinforced and solidified.

[0053] Specifically, after the in-situ mixing and curing of the sidewall forming area 3 and the substrate forming area 4 are completed, the interface area between the two is subjected to secondary mixing and curing to improve the overall connection strength between the sidewall solidified body and the substrate solidified body.

[0054] By performing secondary mixing and curing on the interface area between the sidewall forming area 3 and the substrate forming area 4, the problem of uneven curing or weak bonding that may exist at the interface is eliminated, the overall connection strength between the solidified sidewall body and the solidified substrate body is improved, and the two are ensured to work together to bear the force, thus avoiding structural damage due to insufficient strength in the interface area.

[0055] Preferably, when performing step 3 above, the excavation area 5 is excavated in layers.

[0056] By excavating the excavation zone 5 in layers, soil disturbance during the excavation process is reduced, and the stability of the trench excavation process is improved.

[0057] Preferably, after performing step 3 and before performing step 4, the bearing capacity of the trench base is tested, and step 4 is performed after the test results meet the design requirements.

[0058] Specifically, the bearing capacity of the trench base is tested by at least one of the following methods: plate load test, light dynamic penetration test, or static penetration test. Pipeline foundation construction is carried out after the test results meet the design requirements.

[0059] By employing at least one of the following methods—plate load test, light dynamic penetration test, or static penetration test—to test the bearing capacity of the trench foundation, appropriate testing methods can be flexibly selected according to different soil conditions. This ensures the accuracy and applicability of the test results. Pipeline foundation construction can only proceed after confirming that the foundation bearing capacity meets the design requirements, thus avoiding uneven settlement of the pipeline foundation due to insufficient foundation bearing capacity and ensuring the long-term safety of the pipeline structure.

[0060] Preferably, when performing step 4 above, after the pipeline is laid, the trench is backfilled in layers on both sides simultaneously to reduce displacement caused by uneven stress on the pipeline.

[0061] By simultaneously backfilling both sides of the trench in layers, the stress difference between the two sides of the pipeline is reduced, the risk of pipeline displacement is decreased, and the stability of pipeline laying is improved.

[0062] It should be noted that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding and reading. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0063] The above description is merely a preferred embodiment of the present invention and is 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 person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for in-situ solidification construction of pipeline trenches in soft soil areas without support during excavation, characterized in that, Including the following steps: Step 1: Determine the in-situ curing area based on the trench design and excavation location of the pipeline to be constructed, and divide the in-situ curing area into the sidewall formation area, the base formation area, and the excavation area; Step 2: In-situ mixing and solidification are carried out on the sidewall formation area and the base formation area to form a solidified sidewall body and a solidified base body. The solidification parameters of the excavation area are adjusted according to the soil conditions of the excavation area so that the excavation area at least meets the requirements for the passage of construction equipment and the requirements for soil excavation. Step 3: After the solidified sidewall and solidified base have reached their designed strength, the excavation area is excavated so that the solidified sidewall forms the trench sidewall and the solidified base forms the trench base. Step 4: Construct the pipe foundation on the trench base, and complete the pipe laying and trench backfilling.

2. The in-situ solidification construction method for unsupported excavation of pipeline trenches in soft soil areas as described in claim 1, characterized in that, The sidewall forming area is located on both sides of the excavation area, the base forming area is located below the excavation area, and the sidewall forming area and the base forming area are connected to form a continuous solidification area.

3. The in-situ solidification construction method for unsupported excavation of pipeline trenches in soft soil areas as described in claim 2, characterized in that, The cross-section of the continuously cured area is U-shaped, and the sidewall forming area extends obliquely from top to bottom toward the excavation area.

4. The in-situ solidification construction method for unsupported excavation of pipeline trenches in soft soil areas as described in claim 3, characterized in that, When performing step 1 above, the slope of the sidewall formation area is first determined based on the soil conditions of the in-situ solidification area.

5. The in-situ solidification construction method for unsupported excavation of pipeline trenches in soft soil areas as described in claim 1, characterized in that, After performing step 1 and before performing step 2, surface interception and drainage treatment is carried out on the in-situ solidified area to form a surface slope towards the outside of the in-situ solidified area, and drainage ditches are excavated around the in-situ solidified area.

6. The in-situ solidification construction method for unsupported excavation of pipeline trenches in soft soil areas as described in claim 1, characterized in that, In step 2, the in-situ curing area is divided into multiple construction sections along the length of the trench, and each construction section is mixed and cured in situ in sequence. The curing areas of adjacent construction sections overlap each other to form a sidewall curing body and a base curing body that are continuously set along the length of the trench.

7. The in-situ solidification construction method for unsupported excavation of pipeline trenches in soft soil areas as described in claim 1, characterized in that, When performing step 2 above, the boundary area between the sidewall forming area and the base forming area is reinforced and solidified.

8. The in-situ solidification construction method for unsupported excavation of pipeline trenches in soft soil areas as described in claim 1, characterized in that, When performing step 3 above, the excavation area is excavated in layers.

9. The in-situ solidification construction method for unsupported excavation of pipeline trenches in soft soil areas as described in claim 1, characterized in that, After performing step 3 and before performing step 4, the bearing capacity of the trench base is tested. Step 4 is performed after the test results meet the design requirements.

10. The in-situ solidification construction method for unsupported excavation of pipeline trenches in soft soil areas as described in claim 1, characterized in that, When performing step 4 above, after the pipeline is laid, the trench is backfilled in layers on both sides simultaneously to reduce the displacement caused by uneven stress on the pipeline.

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