Basement bottom plate pressure reducing device

Abstract

The utility model discloses a basement bottom plate pressure reducing device, which is characterized in that a permeable layer, a filter layer and a drainage pipe network are arranged below a basement bottom plate and are combined, and a water collecting well and a water pumping and drainage system are arranged at the end part or the corner position, so that continuous and effective drainage of a high-water-level area below the bottom plate is realized. The permeable layer is composed of gravels or pebbles, the two sides and the top of the permeable layer are covered with geotechnical cloth to prevent sediment deposition, drainage pipelines are laid according to a certain gradient and connected into the water collecting well, a double-pump redundant automatic drainage system is arranged in the water collecting well, and a liquid level monitoring device is used for controlling start and stop of water pumps. The underground water level can be kept far lower than the elevation of the bottom plate under the unattended condition; the water outlet pipe is connected with a municipal drainage pipe network or a rainwater pipe network, and a check valve is additionally arranged to prevent backflow.

Description

Technical Field

[0001] This utility model relates to the technical field of building construction, specifically to a pressure reducing device applied to the basement floor slab. Background Technology

[0002] With increasing urban development and land scarcity, underground space development is becoming increasingly common in modern construction projects. Basement floors are typically located in soil layers with high water tables or abundant water content. Subjected to the buoyancy and seepage pressure of groundwater, failure to drain water promptly or effectively prevent waterproofing can easily lead to structural leakage, uplift, or even severe damage. Therefore, how to quickly and effectively remove groundwater or reduce hydrostatic pressure beneath basement floors has always been a crucial research direction in this field.

[0003] Currently, common pressure reduction methods used in basement engineering practice include:

[0004] 1. A simple thick cushion layer or self-draining layer, by setting a layer of sand or gravel under the foundation, allows some groundwater to naturally collect in a relatively low-lying sump. However, this method depends on the permeability of the soil and the drainage capacity of the drainage medium, and its effect on high water levels or large-area seepage is limited.

[0005] 2. A combination of blind drains and drainage ditches with pumping wells is used. Blind drains are installed in or around the foundation layer to collect water and direct it to a collection well, from which it is then pumped out. This method is widely applicable, but in situations with large groundwater volumes, it can easily lead to blockages in the drainage pipes or insufficient burial depth, resulting in reduced drainage efficiency.

[0006] 3. Combining anti-buoyancy anchors or anti-uplift piles for structural anti-buoyancy: Some projects use "structural anti-buoyancy" to resist the buoyancy of groundwater, rather than relying primarily on drainage. However, this method has high requirements for the cost of the structure itself and the difficulty of construction. If the groundwater level rises further in the future, there are still risks of leakage or safety.

[0007] However, existing technologies still have the following shortcomings in reducing pressure on basement floor slabs:

[0008] Poor drainage or easy blockage: Some traditional blind drains or simple drainage layers are easily blocked by mud and impurities during use, resulting in a decrease in drainage efficiency and making it difficult to guarantee long-term effectiveness.

[0009] The centralized drainage system has a low degree of automation: many projects rely on manual observation or simple float switches. Once the water pump fails or the power is interrupted, drainage cannot be carried out in time, which can lead to a rise in the groundwater level and pose potential safety hazards.

[0010] Waterproofing layers are susceptible to erosion and difficult to maintain: If only the waterproofing layer or self-waterproofing concrete is relied upon without effective drainage and pressure reduction, long-term high water pressure will accelerate the aging of the waterproofing layer or the generation of micro-cracks in the structure. In addition, it is difficult to carry out large-scale excavation and maintenance in the basement area, resulting in high repair costs in the later stage.

[0011] Insufficient applicability and reliability: In complex geological conditions or with high water levels and large flow rates, traditional drainage methods often lack multiple safeguards (such as backup pumps and backflow protection). Once continuous rainfall or extreme conditions occur, the risk of basement water seepage or even floating increases.

[0012] Based on the above problems, how to construct an efficient and reliable pressure-reducing device in the lower part of the basement floor slab or subbase layer, so as to achieve smooth water collection and centralized discharge, and reduce the impact of siltation and water pump shutdown on the overall drainage system, has become a technical problem that urgently needs to be solved in this field. Utility Model Content

[0013] To address the aforementioned issues, this utility model provides a basement floor pressure reduction device. By optimizing the structure and improving the functions of the drainage layer, filter layer, water collection well, and pumping and drainage system, it achieves continuous control of the water pressure below the floor, thereby improving pressure reduction efficiency, reducing maintenance costs, and effectively ensuring the safety and durability of the basement structure.

[0014] Basement floor pressure reduction device, the device comprising:

[0015] A drainage layer, laid below the basement floor slab, is used to collect groundwater from beneath the floor slab.

[0016] A filter layer or geotextile is placed between the drainage layer and the soil to prevent sediment from entering the drainage layer.

[0017] A drainage network, laid within or below the drainage layer, includes several interconnected drainage pipes used to collect and divert groundwater to a predetermined location.

[0018] A water collection well, connected to the drainage pipe network, is used to collect groundwater collected by the drainage pipe network;

[0019] A drainage system, installed in or connected to the collection well, is used to discharge the groundwater to a predetermined discharge channel outside the well, thereby reducing the water pressure below the basement floor.

[0020] In one specific embodiment, the drainage layer is composed of a crushed stone layer or a pebble layer, the drainage layer thickness is 200-300 mm, and geotextile is laid on the top and bottom of the drainage layer.

[0021] In one specific embodiment, the drainage network includes several parallel drainage pipes, each with an installation slope of 0.3% to 0.5%, for guiding groundwater to automatically flow into the collection well.

[0022] In one specific embodiment, a submersible pump with automatic start-stop control is installed at the bottom of the water collection well. The submersible pump monitors the liquid level and performs automatic drainage operations through a float switch or a liquid level sensor.

[0023] In one specific embodiment, the water collection well is equipped with a dual-pump system with one pump in use and one on standby, and is connected to an emergency power supply in case of power failure or sudden accident to ensure continuous drainage.

[0024] In one specific embodiment, a check valve or backflow preventer is installed between the drainage network and the municipal stormwater pipe or nearby water body to prevent backflow of external water.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] 1. To improve drainage flow and reduce the risk of siltation, this technical solution arranges a filter layer or geotextile between the drainage layer and the soil, and improves the material and layout of the drainage pipes. This ensures smooth water flow into the pipe network while effectively preventing silt and fine particles from entering the drainage layer and pipes, significantly reducing the risk of blockage in traditional blind drains or simple drainage layers, and extending the service life of the system.

[0027] 2. To enhance the pressure reduction efficiency under the basement floor slab, multiple parallel or ring-shaped drainage pipes are strategically installed, combined with sump pits and water pumps for centralized drainage. This rapidly reduces the static water pressure beneath the basement floor slab, preventing long-term high water head damage to the slab or waterproofing layer. Compared to existing technologies that rely solely on thick bedding layers or partial drainage ditches, this solution provides a more stable and continuous pressure reduction capability under high water levels or high flow rates.

[0028] 3. Automated and redundant design ensures system reliability. A liquid level sensor or float switch combined with a control device enables automatic start / stop control of the water pump, reducing the burden of manual monitoring. Furthermore, by configuring a dual-pump system (one in operation and one in standby), a backup power supply, or check valves, the drainage system's fault tolerance in the event of pump failure or sudden power outages can be enhanced, ensuring the long-term safety of the basement.

[0029] 4. Effectively protects the base slab structure and waterproof layer, forming a dual protection of "active drainage and pressure reduction + waterproof isolation" below the base slab: on the one hand, it continuously reduces the buoyancy and erosion effect of groundwater on the base slab; on the other hand, it reduces the chance of long-term immersion and penetration of water, thereby delaying or avoiding cracking and seepage problems in the base slab and waterproof layer, significantly improving the service life and safety performance of the basement structure. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the device structure of this utility model.

[0031] 1—Basement floor slab;

[0032] 2—Water collection well;

[0033] 3—First layer of geotextile;

[0034] 4—Gravel layer;

[0035] 5—Second layer of geotextile;

[0036] 6—Drainage layer;

[0037] 7—Drainage pipes;

[0038] 8—Monitor the water pump. Detailed Implementation

[0039] To further illustrate the principle and effects of this utility model, the embodiments of this utility model are described below with reference to the accompanying drawings (but are not limited thereto):

[0040] The following section uses a basement level two project of a comprehensive office building as an example to introduce the specific implementation process and related technical indicators of this technical solution.

[0041] The project occupies a total area of ​​approximately 2,000 square meters, with a basement excavation depth of about 8.5 meters. Geological conditions indicate that the groundwater level is consistently at a depth of about 1.0 to 1.5 meters, and the soil layers are mainly clay and silty sand, with a permeability coefficient of approximately 5.0 × 10⁻⁶. -4 ~8.0×10 -4 cm / s. Due to the high groundwater level, the base slab is highly susceptible to buoyancy and seepage pressure. Therefore, in this embodiment, a special permeable layer and drainage system are installed below the basement base slab 1. The long-term effective control of groundwater is achieved through the coordinated operation of the water collection well 2 and the pumping and drainage equipment.

[0042] During construction, the foundation pit is first excavated to the design elevation, and temporary drainage is maintained within the pit to prevent significant water accumulation at the base. Then, the subgrade or cushion layer is leveled and compacted, followed by the laying of the first layer of geotextile 3, ensuring it is smooth and wrinkle-free with an overlap width of approximately 200 mm or more. Next, a layer of approximately 30 cm thick crushed stone 4 (crushed stone particle size 20-40 mm, mud content not exceeding 1%) is backfilled in layers. During backfilling and light vibration, care is taken to maintain internal voids to ensure good permeability. After backfilling, a second layer of geotextile 5 is placed on top of the crushed stone layer 4, and the overlaps are securely joined using heat fusion or bonding methods. This forms a closed system of "filter layer-crushed stone permeable layer-filter layer" on both the upper and lower sides, maximizing the prevention of surrounding cohesive soil and fine particles from entering the drainage layer 6.

[0043] While laying the drainage layer 6, several drainage pipes 7 are buried on or at the bottom of this layer according to the designed slope. The branch pipes have a diameter of DN100, and the main pipes have a diameter of DN150 or DN200. The pipes are spaced approximately 6 meters apart, and the slope is maintained between 0.3% and 0.5% to facilitate gravity flow. An inspection port or manhole is buried every 15-20 meters for future pipe maintenance operations such as ball flushing or high-pressure cleaning. Two collection wells 2 are located at the confluence of the main drainage pipes, on either side of the basement. Each collection well 2 is cast-in-place reinforced concrete, with an internal net dimension of approximately 1.2 meters × 1.2 meters. Its depth is 10-15 centimeters lower than the elevation of the drainage pipes 7, and a pump pit platform (approximately 0.3 meters above the bottom of the well) is reserved inside the well for installing a submersible pump and for future dredging operations. The outlet pipe is connected to the outdoor rainwater network or municipal drainage network, and a check valve is installed at the interface to prevent backflow of external water.

[0044] In each collection well 2, two submersible pumps with a rated flow rate of approximately 15 cubic meters per hour and a head of 15 meters are placed, one for operation and one for standby. The pump sets are equipped with an automatic float (or level sensor) monitoring system. When the water level in the well reaches the set high water level (usually around 0.6 meters deep), drainage automatically starts, and when the water level drops to the low water level (approximately 0.3 meters deep), the pump automatically stops. In the event of a mains power outage or a main pump failure, the standby pump and emergency power supply can be activated to ensure uninterrupted pumping. Each submersible pump has overcurrent and overheat protection functions and can be linked with the building automation system to trigger a high water level alarm, ensuring timely detection of problems and manual intervention.

[0045] After completing the construction of the drainage layer and sump 2, the concrete foundation layer below the base slab, reinforcement, and waterproof membrane are laid, followed by the final pouring of the basement base slab concrete. During the base slab construction phase, the pre-embedded drainage pipes and sump locations need to be protected to ensure that the well openings and inspection ports are unobstructed, facilitating subsequent commissioning. After the overall system is completed, a 24-48 hour water test is conducted to monitor the automatic start-stop status of pump 8 and the unobstructed flow of the drainage pipeline, and to observe whether the water level in the sump remains stable between high and low levels. Actual testing shows that this solution can maintain the water level in the well at approximately 1 meter below the base slab elevation for an extended period, effectively reducing the risk of the basement base slab floating. The drainage efficiency and automation level are significantly superior to previous methods relying solely on blind drains or simple drainage ditches.

[0046] In subsequent daily use, the project management team can periodically check the pump operation status, maintenance well condition, and surface settlement of the gravel layer as needed, and conduct focused inspections during the rainy season or when water levels are high, turning on the backup pump and clearing debris or silt as necessary. Thanks to the double-layer geotextile protection beneath the permeable layer, silt is unlikely to clog the pipe network over a large area, maintaining good drainage efficiency and saving on later maintenance costs. Overall, by constructing such a complete pressure-reducing device under the basement floor slab—comprising a filter layer, gravel layer, drainage pipe, collection well, and pumping system—not only is the long-term threat of water head to the floor structure reduced, but it also allows for rapid drainage of seepage during high water levels or sudden heavy rainfall, ensuring the safe use of the basement while reducing leakage risks and maintenance pressure.

[0047] In summary, this utility model has broad application prospects in projects involving high groundwater levels and deep foundation basements. The above embodiments are merely illustrative and not intended to limit the scope of this utility model. Those skilled in the art can make equivalent substitutions and improvements without departing from its core principles, and all such modifications are considered to fall within the protection scope of this utility model. Accordingly, the protection scope of this utility model is determined by the claims, and the above description should not be considered a limitation of the claims.

Claims

1. A basement floor depressurization device, characterized by, The device comprises: a drainage layer laid below the basement floor for collecting underground water below the floor; a filter layer or geotextile arranged between the drainage layer and the soil to prevent silt from entering the drainage layer; a drainage pipe network arranged in or below the drainage layer, comprising a plurality of interconnected drainage pipes for collecting and draining underground water to a predetermined location; a water collection well connected to the drainage pipe network for collecting underground water collected by the drainage pipe network; a water pumping system arranged in or connected to the water collection well for pumping the underground water to a predetermined discharge channel outside the well, thereby reducing the water pressure below the basement floor.

2. The basement floor depressurization apparatus according to claim 1, characterized by The drainage layer is composed of a gravel layer or a pebble layer, and the thickness of the drainage layer is 200-300 mm, and geotextile is laid above and below the drainage layer.

3. The basement floor depressurization apparatus according to claim 1 or 2, characterized by, The drainage pipe network comprises a plurality of parallel drainage pipes, and each drainage pipe has an installation slope of 0.3%-0.5% for guiding the automatic flow of underground water into the water collection well.

4. The basement floor depressurization apparatus according to claim 3, characterized by The bottom of the water collection well is provided with an automatically started and stopped submersible pump, and the submersible pump is monitored by a float switch or a liquid level sensor for automatic water pumping operation.

5. The basement floor depressurization apparatus according to claim 4, characterized by A dual-pump system with one main pump and one standby pump is arranged in the water collection well, and an emergency power supply is connected in the case of power failure or sudden accidents to ensure continuous water pumping.

6. The basement floor depressurization apparatus according to claim 5, characterized by A check valve or backflow preventer is arranged between the drainage pipe network and the municipal rainwater pipe or the nearby water body to prevent external water from flowing back.

Images