Complex geological reinforcement method for soft foundation tamping
By combining vacuum prepression and deep-stacking methods, the complex geology of marine silt packages was reinforced, which solved the problem of reinforcement in the surrounding areas of silt packages, achieved uniform reinforcement and efficient construction of the foundation, and reduced costs and environmental pollution.
Patent Information
- Application Number
- CN202411432876.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-15
- Publication Date
- 2024-12-13
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
In the complex geology of silt-packing formed by marine backfill, it is difficult for a single process to achieve uniform reinforcement and deep treatment of the foundation, especially the 'upper stone and lower mud' structure in the surrounding areas of silt-packing leads to poor reinforcement effect, and the existing methods are costly, Low efficiency and high environmental pollution.
Combined with vacuum pre-pressure and deep-stacking method technology, the silt pack and surrounding areas are comprehensively processed through drainage plate setting, gravel cover hole introduction, deep-stacking reinforcement and vibration rolling, etc., to ensure the reinforcement depth. and uniformity.
The uniform reinforcement of the foundation is achieved, the bearing capacity and compression modulus are improved, the settlement deformation is reduced, the construction cost and environmental pollution are reduced, and the construction efficiency and economic benefits are improved.
Smart Images
Figure CN119121899A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of foundation treatment construction, and in particular to a complex geological reinforcement method for tamping a soft foundation. Background Art
[0002] With the continuous development of economic construction, land reclamation in coastal areas has become a construction trend. Under the conditions of direct backfilling to form land in coastal areas, the silt is often squeezed and bulged upward to form silt bags due to improper backfilling sequence or excessive thickness of the underlying silt. Due to the complex geological structure of the silt bag, it is difficult to achieve good reinforcement by a single process. Especially in the area surrounding the silt bag, its unique "upper stone and lower mud" structure is a difficult problem to deal with. Its geological characteristics are that the center of the silt bag is silt, and the area surrounding the silt bag, that is, the transition zone, is silt in the lower layer and mountain stone in the upper layer, and the cross section is "triangular". This geology cannot meet the design requirements by vacuum preloading technology alone. Especially for the treatment of the transition zone, if it is directly treated by strong tamping and other processes, a mud-stone mixed layer will be formed, which will cause long-term excessive settlement. How to ensure uniform bearing capacity of the foundation after reinforcement, high overall construction efficiency and low process cost is a process problem that needs to be solved urgently.
[0003] The Chinese invention patent (application number CN201711317659.X) discloses a construction method for punched cast-in-place piles on partially buried silt bags. This method provides a construction method for punched cast-in-place piles on partially buried silt bags in reclamation areas, solving the problem that the existing punched cast-in-place piles cannot be constructed normally due to serious shrinkage and collapse when encountering buried silt bags. However, this method is only applicable to cast-in-place pile technology, and the cost of large-scale construction is too high and it cannot meet the problem of rigid transition of bearing capacity after treatment of different geological conditions, i.e. the surrounding areas of silt bags.
[0004] China's invention patent CN103031836A, a method for quickly building a road on a newly blown silt foundation, discloses the following steps for construction: (1) setting up a working layer; (2) laying a sand cushion layer on the working layer; (3) setting up a vertical drainage body; (4) setting up a horizontal drainage channel in the sand cushion layer and connecting it to a pumping and drainage device; (5) performing graded loading construction in the area to be reinforced; (6) the construction machinery walks on the surface of the area to be reinforced to apply a dynamic load, and uses the pile load as a static load for preloading, while starting the pumping and drainage device to drain water and reinforce the foundation; (7) after the preloading is completed, the pumping and drainage device is removed and the horizontal drainage channel is blocked. Although this method reinforces the foundation through preloading and drainage, it does not specifically reinforce the complex geology of the silt bag formed by offshore backfilling, and may not be able to ensure the uniformity and depth of the reinforcement, thereby affecting the overall bearing capacity and stability of the foundation.
[0005] China's invention patent CN102296591A, a method for rapid drainage and consolidation of soft soil foundation, discloses that (1) the silt is excavated to 2-3m below the completion elevation, the first layer of sand is backfilled to 0.8-1.2m below the completion elevation while excavating, a plastic drainage board is inserted to a depth of 8m below the completion elevation, a second sand cushion layer is covered to 0.5-1.5m above the completion elevation, and a drainage system is set up to continuously pump water; (2) the first dynamic load is started 12-18 days after the backfill is in place, with an energy of 500-650 kJ , the depth of the tamping pit does not exceed 1.5m; (3) 5-8 days later, the second dynamic load, the energy is 700-900 kJ, the depth of the tamping pit does not exceed 1.5m, (4) 5-8 days later, the third dynamic load, the energy is 1100-1500 kJ, the depth of the tamping pit does not exceed 1.5m; (5) 5-8 days later, the fourth dynamic load, the energy is 1800-2200 kJ, the depth of the tamping pit does not exceed 1.5m; (6) 5-8 days later, the excess filler is excavated and transported, and the whole site is dynamically loaded with 600 kJ, and the project is leveled and completed twice. This method uses multiple dynamic loads to strengthen the foundation. Although it can improve the density of the foundation, each dynamic load consumes a lot of energy and the construction efficiency is relatively low, which increases the construction cost and time. Despite multiple dynamic load treatments, the tamping pit depth of each dynamic load is strictly controlled (no more than 1.5m), which may not be able to effectively treat deeper silt layers, affecting the reinforcement depth. Furthermore, multiple dynamic loads may cause significant vibrations to the surrounding environment, affecting the safety of surrounding buildings or facilities.
[0006] China's invention patent for silt surface solidification treatment process CN101476317A discloses inserting a drain board on the silt surface by a plate inserting machine; connecting the drain board to the drain board connection pipeline by using the drain board; and discharging the water vapor in the silt surface through the drain board connection pipeline under the action of vacuum negative pressure. This method mainly uses the drain board for drainage treatment. Although it can effectively reduce the water content of the silt, it lacks other reinforcement measures, which may lead to a single reinforcement effect and is insufficient to meet the foundation reinforcement needs under complex geological conditions. Summary of the invention
[0007] In order to solve the problem of difficult foundation treatment in the area around the silt bag with its unique "upper stone and lower mud" structure, the present invention provides a reinforcement method for the complex geology of the silt bag formed by offshore backfilling. Under the premise of ensuring the reinforcement treatment depth, vacuum preloading and deep in-hole tamping process are combined to treat the silt bag and its surrounding areas, which is expected to have a strong compaction effect, a large and uniform foundation reinforcement treatment depth, a high compression modulus of the composite foundation, small settlement deformation, and good bearing properties.
[0008] The technical solution adopted by the present invention to solve the above problems is: a reinforcement method for complex geology of silt packs formed by offshore backfilling, comprising the following steps: S1: Construction preparation, geological and topographic survey of the silt bag, drawing of cross-section diagram, cleaning and leveling of the top of the silt bag; S2: Install drainage boards. Install vertical drainage boards at the silt packs and install oblique drainage boards at the triangular areas of the silt packs, so that the triangular areas of the silt packs under the gravel cover layer also have drainage channels. The drainage boards should penetrate the silt layer and enter the soft soil layer 0.5m; S3: Vacuum drainage and consolidation of silt bag soil, the construction sequence is fixing the drainage board, filling sand to fix the board, digging the sealing film pressing trench, laying the sealing film, vacuum drainage, and vacuum unloading; S4: Drilling holes in the gravel overburden around the silt pack. Drilling holes include direct impact drilling and rotary drilling. If the gravel overburden around the silt pack is ≤5m thick, direct impact drilling is used. If the gravel overburden is >5m thick, rotary drilling is used. The drilling holes should pass through the gravel overburden. S5: Deep tamping reinforcement of the silt bag triangle area, fill the rated crushed stone filling into the lead hole, and use the tamping hammer to hit the filling several times after each filling, until each filling is firmly tamped, and circulate the filling and tamping to the top of the pile hole, and the replacement pile construction is completed; S6: General tamping construction. After vacuum preloading and deep tamping reinforcement in the hole are completed, the silt bag foundation treatment area is leveled and then measured and laid out, and general tamping construction is carried out; S7: Vibration compaction. Finally, a vibration press is used to vibrate and compact the sludge bag until it is firm.
[0009] The present invention is applicable to soft foundations such as silt and river channels, and complex geological structures where the backfill material squeezes the underlying silt to form silt bags. The silt is drained and consolidated, and after the silt is drained and consolidated, the silt overlying the quarrying rock in the transition zone around the silt bag is treated with deep tamping to solve the problem of difficult treatment of the silt bag and the mud-rock interface around the silt bag. It has the following advantages: (1) Comprehensive treatment process, highly targeted: The present invention combines a variety of reinforcement methods, including drainage board installation, vacuum preloading drainage consolidation, gravel cover layer drilling, deep layer tamping reinforcement, general tamping construction and vibration rolling, etc., and conducts comprehensive and targeted treatment for different geological conditions, especially the complex structure of silt packs and their surroundings with "stone above and mud below". This comprehensive treatment method can effectively solve problems that are difficult to handle with a single process and improve the overall reinforcement effect.
[0010] (2) Strong adaptability and flexible construction: Different drilling techniques are used to drill holes, including direct impact drilling and rotary drilling composite drilling techniques to adapt to gravel covering layers of different thicknesses. In order to reduce mutual interference during construction and ensure the quality of drilling, the drilling is carried out in sequence using an interval skipping method.
[0011] (3) Reduce construction costs and improve economic benefits: The present invention avoids the high cost problem caused by single process treatment by optimizing the construction process and adopting reasonable composite reinforcement means. It is not a simple superposition of single processes, but a combination of multiple single processes such as drainage, hole drawing, and strong tamping, and innovative technologies such as deep rotary drilling and shallow direct impact hole drawing, two different hole-making methods, are innovatively composited to form the comprehensive treatment process of the present invention, which not only improves the construction efficiency and shortens the construction period, thereby reducing the overall project cost and improving the economic benefits.
[0012] (4) Environmental protection and energy saving, reducing environmental pollution: In the reinforcement process, the present invention mainly uses physical methods such as drainage, consolidation, and strong tamping to treat the foundation, which reduces the use of chemical reinforcement materials and reduces environmental pollution. At the same time, by optimizing the construction process, energy consumption is reduced, reflecting the concept of environmental protection and energy saving.
[0013] (5) High construction efficiency and short construction period: The reinforcement method provided by the present invention has clear steps and is easy to operate, and can quickly and effectively reinforce the complex geology of the silt pack. In particular, in the treatment of the area surrounding the silt pack, by reasonably arranging the construction sequence and selecting appropriate reinforcement means, the construction efficiency is significantly improved and the construction period is shortened. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 It is a construction flow chart; The construction foundation of the dynamic compaction method and the vacuum preloading method was improved, and deep foundation treatment was effectively carried out for different construction conditions under the construction conditions of soft foundation and complex geology. After the treatment, the foundation bearing capacity of the silt bag and the surrounding area met the design requirements, and the rigid transition was good, which provided experience for the construction of other similar projects in the future.
[0015] The present invention is described above by way of example. It should be noted that, without departing from the core of the present invention, any simple deformation, modification or other equivalent replacement that can be made by those skilled in the art without inventive effort falls within the protection scope of the present invention.
Claims
1. A complex geological reinforcement method for soft foundation tamping, characterized in that: The following steps are involved: S1: Construction preparation, geological and topographic survey of the silt bag, drawing of cross-section diagram, cleaning and leveling of the top of the silt bag; S2: Install drainage boards. Install vertical drainage boards at the silt packs and install oblique drainage boards at the triangular areas of the silt packs, so that the triangular areas of the silt packs under the gravel cover layer also have drainage channels. The drainage boards should penetrate the silt layer and enter the soft soil layer 0.5m; S3: Vacuum drainage and consolidation of silt bag soil, the construction sequence is fixing the drainage board, filling sand to fix the board, digging the sealing film pressing trench, laying the sealing film, vacuum drainage, and vacuum unloading; S4: Drilling holes in the gravel overburden around the silt pack. Drilling holes include direct impact drilling and rotary drilling. If the gravel overburden around the silt pack is ≤5m thick, direct impact drilling is used. If the gravel overburden is >5m thick, rotary drilling is used. The drilling holes should pass through the gravel overburden. S5: Deep tamping reinforcement of the silt bag triangle area, fill the rated crushed stone filling into the lead hole, and use the tamping hammer to hit the filling several times after each filling, until each filling is firmly tamped, and circulate the filling and tamping to the top of the pile hole, and the replacement pile construction is completed; S6: General tamping construction. After vacuum preloading and deep tamping reinforcement in the hole are completed, the silt bag foundation treatment area is leveled and then measured and laid out, and general tamping construction is carried out; S7: Vibration compaction. Finally, a vibration press is used to vibrate and compact the sludge bag until it is firm.
2. A complex geological reinforcement method for soft foundation tamping according to claim 1, characterized in that: The S2 oblique drainage board determines the cross-sectional shape of the sludge bag and the slope of the oblique drainage board according to the geological survey of the sludge bag.
3. A complex geological reinforcement method for soft foundation tamping according to claim 1, characterized in that: The pile frame of the board inserting machine used in the drainage board installed by S2 has an angle adjustment function, and its adjustment angle is not less than 30 degrees.
4. A complex geological reinforcement method for soft foundation tamping according to claim 1, characterized in that: The S301 drainage board pipeline connection in the S3, the connection between the vacuum branch filter pipes and between the vacuum branch filter pipes and the main filter pipe adopts matching straight-through and three-way joints. The joints are firmly sealed, and a wire rubber hose flexible joint is provided every 25m-30m along the length direction for the connection of the vacuum main pipe; S302 is backfilled with sand cushion layer, and the laying thickness of the medium-coarse sand drainage cushion layer is 0.3m; during the vacuum pumping process, the normal operation of the jet pump must be maintained, the circulating water in the jet box must be continuously replenished, the water pump and motor must be regularly repaired and maintained, and a certain number of spare water pumps and motors must be provided. After constant load, the designed vacuum pressure is guaranteed to be reached during the vacuum pumping process to ensure a 100% pump start-up rate.