A cofferdam preloading and consolidation device for soft soil foundation

Abstract

This utility model discloses a cofferdam preloading reinforcement device for soft soil foundations, comprising a cofferdam, a sealing membrane, a vacuum device, a surcharge soil layer, a sand cushion layer, and a longitudinal drainage board. The cofferdam is fixed around the soft soil foundation and is ring-shaped. The sealing membrane is laid inside the cofferdam and at least completely covers the soft soil foundation within the cofferdam. The sand cushion layer is laid on the soft soil foundation within the cofferdam, and the surcharge soil layer is laid on the soft soil foundation within the cofferdam, with the sand cushion layer located below the surcharge soil layer. The sealing membrane is laid between or below the sand cushion layer and the surcharge soil layer. The vacuum device is connected to the longitudinal drainage board and is located outside the cofferdam. The longitudinal drainage board is vertically inserted into the soft soil foundation within the cofferdam and is located below the sand cushion layer. This utility model accelerates the drainage and consolidation process of the soft soil foundation, shortens the reinforcement time, and achieves better preloading effect.

Description

Technical Field

[0001] This utility model relates to the technical field of soft soil foundation reinforcement devices, specifically a cofferdam preloading reinforcement device for soft soil foundations. Background Technology

[0002] In projects such as ports, airports, sluice gate foundations, and roads, it is often necessary to reinforce soft soil foundations over large areas. This requires the use of specialized soft soil foundation reinforcement devices. Existing soft soil foundation reinforcement devices generally employ a single reinforcement method, such as using water-filled bags to gradually drain and consolidate the soft soil foundation during loading (increasing the load). This bag-loading method requires filling the bags with fill material, making the operation more cumbersome. Furthermore, this method suffers from problems such as easy damage at stress concentration points, uneven loading, and difficulty in controlling the water bag's seal. Additionally, existing reinforcement devices may employ vacuum preloading. Vacuum preloading can typically achieve a load of no more than 80-100 kPa, equivalent to a 4-5m surcharge. For scenarios requiring reinforcement of soft soil foundations thicker than 5m or with a bearing capacity greater than 100 kPa, simple vacuum preloading cannot achieve the desired effect. Utility Model Content

[0003] In view of the shortcomings of the prior art, the purpose of this utility model is to provide a cofferdam surcharge preloading reinforcement device for soft soil foundation, which can solve the problems described in the background art.

[0004] The technical solution to achieve the purpose of this utility model is as follows: a cofferdam preloading reinforcement device for soft soil foundation, comprising a cofferdam, a sealing membrane, a vacuum pumping device, a surcharge soil layer, a sand cushion layer, and a longitudinal drainage board. The cofferdam is fixed around the soft soil foundation and is ring-shaped. The sealing membrane is laid inside the cofferdam and at least completely covers the soft soil foundation inside the cofferdam. The sand cushion layer is laid on the soft soil foundation inside the cofferdam.

[0005] The surcharge soil layer is laid on the soft soil foundation inside the cofferdam, and the sand cushion layer is located below the surcharge soil layer.

[0006] The sealing membrane is laid between the sand cushion layer and the surcharge soil layer or below the sand cushion layer.

[0007] The vacuum pumping device is connected to the longitudinal drainage board. The vacuum pumping device is located outside the cofferdam, and the longitudinal drainage board is vertically inserted into the soft soil foundation inside the cofferdam. The longitudinal drainage board is located below the sand cushion layer.

[0008] Furthermore, the sand cushion layer is made of sand or gravel, with a thickness of 300 mm, and the slab soil layer has a thickness of 500 mm and a unit weight of 16 kN / m³. 3 .

[0009] Furthermore, it includes a geogrid laid on a sand cushion layer, and a surcharge layer laid on the geogrid.

[0010] Furthermore, the sealing membrane includes a first sealing membrane and a second sealing membrane, the first sealing membrane being located between the sand cushion layer and the surcharge soil layer, and the second sealing membrane being located below the sand cushion layer.

[0011] Furthermore, the longitudinal drainage board is long enough to be inserted into the silt or clay layer within the soft soil foundation, with the clay layer being deeper than the silt layer.

[0012] Furthermore, the longitudinal drainage board is a plastic drainage board or a sand well, with a width of 100 mm and a thickness of 3.5 mm, and the interval between two adjacent longitudinal drainage boards is set to 1 m.

[0013] Furthermore, water is stored within the cofferdam to form a sump water pool, which is located above the sump soil.

[0014] Furthermore, it also includes foam boards, which float on the surface of the sump water tank.

[0015] Furthermore, it also includes a drainage pipe, which is laid horizontally on the soft soil foundation within the cofferdam. The drainage pipe is located below the sand cushion layer, and the longitudinal drainage board is connected to the drainage pipe. The end of the drainage pipe is connected to a vacuum pumping device.

[0016] Furthermore, the cofferdam includes several splicing components, which are fixed to the soft soil foundation and sequentially spliced ​​together to form a ring, thereby enabling the splicing components and the soft soil foundation to jointly form a cofferdam.

[0017] The splicing component includes a latch, a rib, an inverted T-shaped plate, and a groove. One end of the inverted T-shaped plate is embedded in the groove, and the other end of the inverted T-shaped plate extends out of the groove. A latch is provided at the end of the inverted T-shaped plate that extends out of the groove, and a latch is also provided on the groove. The two ends of the rib are respectively fastened to the two latches.

[0018] The beneficial effects of this invention are as follows: This invention combines vacuum and surcharge preloading, employing both soil and water tank surcharge preloading to accelerate the drainage and consolidation process of soft soil foundations, shorten reinforcement time, and achieve better preloading results. Furthermore, the spliced ​​components are easy to construct, and the construction of cofferdams is more efficient. The spliced ​​components are reusable, energy-saving and environmentally friendly, eliminating the need for bagged surcharge preloading such as water bags, thus improving economic efficiency. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of this utility model;

[0020] Figure 2 This is a schematic diagram of the cofferdam structure;

[0021] In the diagram, 1-cofferdam, 101-locking buckle, 102-rib plate, 103-inverted T-shaped plate, 104-groove, 2-vacuum pumping device, 3-seepage barrier board, 4-soil layer, 5-geogrid, 6-first sealing membrane, 7-drainage pipe, 8-second sealing membrane, 9-sand cushion layer, 10-longitudinal drainage board, 11-foam board. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0023] like Figures 1-2 As shown, a cofferdam 1 for preloading and reinforcing a soft soil foundation includes a cofferdam 1, a sealing membrane, a vacuum device 2, a slack soil layer 4, a sand cushion layer 9, and a longitudinal drainage board 10. The cofferdam 1 is fixed around the soft soil foundation and is ring-shaped, with the soft soil foundation being the bottom of the cofferdam 1. The sealing membrane is laid inside the cofferdam 1 and extends at least to the inner side wall of the cofferdam 1, so that the sealing membrane can at least completely cover the soft soil foundation inside the cofferdam 1. For example, the sealing membrane is laid on the soft soil foundation inside the cofferdam 1 and extends to the outer side of the cofferdam 1, thereby completely sealing and covering the soft soil foundation inside the cofferdam 1. The sand cushion layer 9 is laid on the soft soil foundation inside the cofferdam 1. The sand cushion layer 9 can be made of sand or gravel with good permeability. The thickness of the sand cushion layer 9 is 300 mm. The sand cushion layer 9 completely covers the soft soil foundation. The function of the sand cushion layer 9 is to provide drainage channels for the drainage of the pumped pore water. That is, there are gaps between the sand or gravel on the sand cushion layer 9. These gaps form drainage channels. The drainage channels are set horizontally to ensure smooth drainage.

[0024] Understandably, the sand cushion layer 9 can be adjusted according to the actual situation to form sand cushion layer 9 of other thicknesses, such as 200 mm or 400 mm or other thicknesses.

[0025] The surcharge soil layer 4 is laid on the soft soil foundation within the cofferdam 1, and the sand cushion layer 9 is located below the surcharge soil layer 4, that is, the surcharge soil layer 4 is laid on the sand cushion layer 9. The surcharge soil layer 4 has a thickness of 500 mm and a unit weight of 16 kN / m³. 3 The function of the surcharge soil layer 4 is to generate vertical pressure on the soft soil foundation through its own weight (its own gravity), so as to promote the discharge of pore water in the soft soil foundation, that is, the pore water flows out from the soft soil foundation. At the same time, it also serves to ensure the stability of the surcharge water pool inside the cofferdam 1, and to provide a working platform for subsequent construction operations.

[0026] Understandably, the thickness and unit weight of the surcharge soil layer 4 can be adjusted according to the actual situation, and surcharge soil layers 4 with other thicknesses and unit weights can be formed, for example, forming a surcharge soil layer 4 with a thickness of 400 mm or 600 mm, forming a 14 kN / m³ surcharge soil layer.3 or 20kN / m 3 Heavy load soil layer 4.

[0027] For example, it also includes a geogrid 5, which is laid on the sand cushion layer 9, and the slack soil layer 4 is laid on the geogrid 5. The geogrid 5 can prevent sharp objects such as gravel in the slack soil layer 4 from puncturing the sealing membrane.

[0028] The sealing membrane is laid between the sand cushion layer 9 and the slack soil layer 4 or below the sand cushion layer 9. When the sealing membrane is laid below the sand cushion layer 9, that is, when the sealing membrane is laid on the surface of the soft soil foundation, the sand cushion layer 9 is then laid on the sealing membrane.

[0029] For example, the sealing membrane includes a first sealing membrane 6 and a second sealing membrane 8, the first sealing membrane 6 being located between the sand cushion layer 9 and the slack soil layer 4, and the second sealing membrane 8 being located below the sand cushion layer 9.

[0030] The sealing membrane is made of plastic film material with good airtightness and aging resistance to seal the entire surface of the soft soil foundation. The density of the sealing membrane is set to maintain the vacuum level during the subsequent vacuum preloading process.

[0031] The vacuum pumping device 2 is connected to the longitudinal drainage board 10 and is located outside the cofferdam 1. The longitudinal drainage board 10 is vertically inserted into the soft soil foundation within the cofferdam 1, and is located below the sand cushion layer 9. The function of the longitudinal drainage board 10 is to shorten the drainage path of pore water in the soft soil foundation, thereby accelerating the drainage and consolidation process. Multiple longitudinal drainage boards 10 are provided, and each longitudinal drainage board 10 is arranged in parallel and spaced apart within the soft soil foundation; for example, they can be inserted into the soft soil foundation at equal intervals.

[0032] The longitudinal drainage board 10 is long enough to be inserted into the silt or clay layer within the soft soil foundation, with the clay layer being deeper than the silt layer, meaning the clay layer is located below the silt layer. The specific length and insertion depth of the longitudinal drainage board 10 within the soft soil foundation can be determined based on the required reinforcement depth of the soft soil foundation.

[0033] It is understood that the longitudinal drainage board 10 can be a plastic drainage board or a sand well. The longitudinal drainage board 10 has a width of 100 mm and a thickness of 3.5 mm, and the interval between two adjacent longitudinal drainage boards 10 is generally set to 1 m.

[0034] For example, the cofferdam 1 also stores water to form a surcharge water pool, which is located above the surcharge soil. The water depth of the surcharge water pool is generally 2-2.5 m. By injecting water into the cofferdam 1 to form the surcharge water pool, the surcharge water pool acts as a liquid phase load, so that the generated water pressure acts on the soft soil foundation, further promoting the discharge of pore water and accelerating the consolidation of the soft soil foundation. The surcharge water pool and the surcharge soil layer 4 together generate a load on the soft soil foundation, realizing the discharge of pore water and the consolidation of the soft soil foundation.

[0035] For example, it also includes a foam board 11, which floats on the surface of the water in the surcharge tank. The foam board 11 can effectively prevent the water in the surcharge tank from evaporating too quickly. When the water level in the surcharge tank changes significantly and deviates severely from the preset water level, it can be restored to the preset water level by timely water injection.

[0036] For example, it also includes a drainage pipe 7, which is laid horizontally on the soft soil foundation within the cofferdam 1. The drainage pipe 7 is located below the sand cushion layer 9, that is, between the sand cushion layer 9 and the surface of the soft soil foundation. The longitudinal drainage board 10 is connected to the drainage pipe 7, and the end of the drainage pipe 7 is connected to the vacuum pumping device 2.

[0037] For example, multiple vacuum pumping devices 2 are provided, each vacuum pumping device 2 is arranged around the cofferdam 1 and is located outside the cofferdam 1. Correspondingly, multiple drainage pipes 7 are also provided, and the two ends of the same drainage pipe 7 are respectively connected to a vacuum pumping device 2.

[0038] For example, the cofferdam 1 includes several splicing components, which are fixed to the soft soil foundation and sequentially spliced ​​together to form a ring, thereby enabling the splicing components and the soft soil foundation to jointly enclose a cofferdam 1. Each splicing component includes a latch 101, a rib 102, an inverted T-shaped plate 103, and a groove 104. One end of the inverted T-shaped plate 103 is embedded in the groove 104, and the other end extends out of the groove 104. A latch 101 is provided at the end of the inverted T-shaped plate 103 extending out of the groove 104, and a latch 101 is also provided on the groove 104. Both ends of the rib 102 are respectively fastened to two latches 101. The grooves 104 of each splicing component connect the various splicing components together through splicing. The splicing of the grooves 104 can be achieved through a convex-concave latch 101 structure. The groove 104 can be a plastic structural component with a groove 104.

[0039] The rib plate 102 enhances the stability of the cofferdam 1, thereby enhancing the stability of the surcharge pool within the cofferdam 1. The sidewall of the groove 104 and one end of the inverted T-shaped plate 103 extending out of the groove 104 together form the sidewall of the groove 104. The sealing membrane extends to the outside of the end of the inverted T-shaped plate 103 extending out of the groove 104, thus extending the sealing membrane to the outside of the groove 104.

[0040] For example, it also includes a seepage barrier 3, which is connected to the lower end of the groove 104 and inserted into the soft soil foundation, that is, one end of the seepage barrier 3 is inserted into the soft soil foundation outside the cofferdam. The insertion depth of the seepage barrier 3 is 150-200 mm, so as to press the edge of the sealing membrane extending outside the groove into the sealing trench, and backfill and compact it with clay to prevent air leakage. The sealing trench is located outside the cofferdam.

[0041] In actual use, the air in the soft soil foundation can be extracted by the vacuum device 2 to form a vacuum pressure, which causes the pore water to flow out from the soft soil foundation and then to the longitudinal drainage plate 10. The pore water flows along the longitudinal drainage plate 10 to the drainage pipe 7. Figure 1 The arrows indicate the direction of pore water flow. The vacuum pressure created by the vacuum pump 2 accelerates the consolidation of the soft soil foundation. Simultaneously, the surcharge preloading through the surcharge soil layer 4 and the surcharge water tank also accelerates the consolidation. Thus, vacuum preloading and surcharge preloading work synergistically to reinforce the soft soil foundation, resulting in a better reinforcement effect compared to traditional single reinforcement methods. Furthermore, unlike the bagged method, this application does not require bags; it only requires laying the surcharge soil layer 4, avoiding the shortcomings of traditional bagged surcharge methods.

[0042] An example of the cofferdam 1 surcharge preloading reinforcement device applied to the soft soil foundation is from a deep soft soil foundation reinforcement project in a port project in the coastal area of ​​South China. First, a 30 cm thick horizontal sandy drainage layer, serving as sand cushion layer 9, is laid on the surface of the soft soil foundation. Then, plastic drainage boards, spaced 1.2 meters apart and inserted to a depth of 25 meters, serve as longitudinal drainage boards 10. After the longitudinal drainage boards 10 are laid, a sealing membrane is laid and a sealing trench is set, with a depth of 1.5 meters. Next, a 60 cm thick sand layer is laid on the sealing membrane, serving as surcharge soil layer 4, with a sand unit weight of 16 kN / m³. Then, self-stabilizing plastic boards are arranged on the sand layer to form cofferdam 1, with the self-stabilizing plastic boards serving as the connecting components. The water depth inside cofferdam 1 is 2.5 meters to form a water pool within cofferdam 1. Finally, a vacuum pumping device 2 is connected and activated to maintain a vacuum level of 82 kPa. During the preloading process, real-time monitoring was conducted using pore water pressure gauges at different depths in the soft soil foundation, surface and deep settlement observation points, and inclinometers. Based on the monitoring data, in the initial stage of preloading, due to the rapid dissipation of pore water pressure, the water injection volume in the water tank was appropriately increased to maintain a higher liquid phase load pressure. In the middle stage of preloading, when the settlement rate of the soft soil foundation was found to have slowed down, the vacuum degree was slightly increased to further promote the discharge of pore water. In the later stage of preloading, based on the test results of the physical and mechanical properties of the soft soil foundation, the loads of each phase (the loads formed by the surcharge water tank and surcharge soil layer 4) were gradually reduced until the reinforcement effect met the engineering design requirements. The entire preloading reinforcement process lasted for 90 days, and all indicators of the reinforced foundation soil met the requirements for port engineering construction.

[0043] This invention combines vacuum and surcharge preloading, employing both soil and water tank surcharge preloading to accelerate the drainage and consolidation process of soft soil foundations, shorten reinforcement time, and achieve better preloading results. Furthermore, the spliced ​​components are easy to construct, and the construction of the cofferdam 1 is more efficient. The spliced ​​components are reusable, energy-saving and environmentally friendly, eliminating the need for bagged surcharge preloading such as water bags, thus improving economic efficiency.

[0044] The embodiments disclosed in this specification are merely illustrative of one aspect of the features of this utility model. The protection scope of this utility model is not limited to this embodiment, and any other functionally equivalent embodiments fall within the protection scope of this utility model. Those skilled in the art can make various other corresponding changes and modifications based on the technical solutions and concepts described above, and all such changes and modifications should fall within the protection scope of the claims of this utility model.

Claims

1. A cofferdam preloading reinforcement device for soft soil foundations, characterized in that, The system includes a cofferdam, a sealing membrane, a vacuum pump, a surcharge soil layer, a sand cushion layer, and longitudinal drainage boards. The cofferdam is fixed around and fixed to the soft soil foundation. The cofferdam is ring-shaped. The sealing membrane is laid inside the cofferdam and at least completely covers the soft soil foundation within the cofferdam. The sand cushion layer is laid on the soft soil foundation within the cofferdam. The surcharge soil layer is laid on the soft soil foundation inside the cofferdam, and the sand cushion layer is located below the surcharge soil layer. The sealing membrane is laid between the sand cushion layer and the surcharge soil layer or below the sand cushion layer. The vacuum pumping device is connected to the longitudinal drainage board. The vacuum pumping device is located outside the cofferdam, and the longitudinal drainage board is vertically inserted into the soft soil foundation inside the cofferdam. The longitudinal drainage board is located below the sand cushion layer.

2. The cofferdam preloading reinforcement device for soft soil foundation according to claim 1, characterized in that, The sand cushion layer is made of sand or gravel, with a thickness of 300 mm, and the slab soil layer has a thickness of 500 mm and a unit weight of 16 kN / m³. 3 .

3. The cofferdam preloading reinforcement device for soft soil foundation according to claim 1, characterized in that, It includes a geogrid, which is laid on a sand cushion layer and a saturated soil layer is laid on the geogrid.

4. The cofferdam preloading reinforcement device for soft soil foundation according to claim 1, characterized in that, The sealing membrane includes a first sealing membrane and a second sealing membrane. The first sealing membrane is located between the sand cushion layer and the surcharge soil layer, and the second sealing membrane is located below the sand cushion layer.

5. The cofferdam preloading reinforcement device for soft soil foundation according to claim 1, characterized in that, The longitudinal drainage board is long enough to be inserted into the silt or clay layer in the soft soil foundation, with the clay layer being deeper than the silt layer.

6. The cofferdam preloading reinforcement device for soft soil foundation according to claim 1, characterized in that, The longitudinal drainage board is made of plastic or sand. The width of the longitudinal drainage board is 100 mm and the thickness is 3.5 mm. The interval between two adjacent longitudinal drainage boards is set to 1 m.

7. The cofferdam preloading reinforcement device for soft soil foundation according to claim 1, characterized in that, The cofferdam also stores water to form a sump water pool, which is located above the sump soil.

8. The cofferdam preloading reinforcement device for soft soil foundation according to claim 7, characterized in that, It also includes foam boards, which float on the surface of the sump water tank.

9. The cofferdam preloading reinforcement device for soft soil foundation according to claim 1, characterized in that, It also includes a drainage pipe, which is laid horizontally on the soft soil foundation inside the cofferdam. The drainage pipe is located below the sand cushion layer. The longitudinal drainage board is connected to the drainage pipe, and the end of the drainage pipe is connected to a vacuum pumping device.

10. The cofferdam preloading reinforcement device for soft soil foundation according to any one of claims 1-9, characterized in that, The cofferdam comprises several interlocking components, which are fixed to the soft soil foundation and sequentially assembled to form a ring, thereby enabling the interlocking components and the soft soil foundation to jointly enclose a cofferdam. The splicing component includes a latch, a rib, an inverted T-shaped plate, and a groove. One end of the inverted T-shaped plate is embedded in the groove, and the other end of the inverted T-shaped plate extends out of the groove. A latch is provided at the end of the inverted T-shaped plate that extends out of the groove, and a latch is also provided on the groove. The two ends of the rib are respectively fastened to the two latches.

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