Dam foundation seepage distributed automatic monitoring device based on artificial heat source

Abstract

The invention relates to a dam foundation seepage distributed automatic monitoring device based on an artificial heat source, which comprises a vertical monitoring pipe, a double-cavity temperature control water tank and circulation control module and a data acquisition and early warning module, the vertical monitoring pipe is vertically arranged, and the double-cavity temperature control water tank and circulation control module is used for periodically heating water in the water tank; a distributed optical fiber temperature sensor of the data acquisition and early warning module is used for measuring the temperature in the vertical monitoring pipe in real time and transmitting the acquired temperature data to the data processing module; the data processing module is used for receiving and storing the temperature data collected from the distributed optical fiber temperature sensor and automatically calculating the seepage velocity according to the cooling curve of the vertical monitoring pipe; the alarm module issues alarm information. According to the invention, automatic monitoring and early warning of seepage of the dam foundation of the earth and rockfill dam with the deep covering layer can be realized, and the construction and maintenance cost is reduced.

Description

Technical Field

[0001] The invention relates to a distributed automatic monitoring device for dam foundation seepage based on an artificial heat source. Background Art

[0002] Dam projects often face challenges of complex geological conditions such as deep overburden, especially in southwest my country, where deep overburden foundations are common. Deep overburden usually refers to loose Quaternary sediments with a thickness of more than 30 meters, which have loose structure, discontinuous lithology, and high permeability. During the operation of the dam, seepage is not limited to the inside of the dam body, but the seepage in the dam foundation soil also needs to be paid great attention.

[0003] When planning and building a dam on a deep overburden, earth-rock dams are often the preferred dam type because they are less affected by geological conditions and are widely used. At present, dam seepage monitoring mainly focuses on the dam body, which is mainly attributed to two points: first, the dam foundation is often directly located on hard bedrock, and the seepage volume at the dam foundation is extremely small; second, the dam foundation is usually treated with anti-seepage treatment, which further reduces the possibility of abnormal seepage. However, when encountering a deep overburden and the excavation cost is high, and the dam foundation cannot be directly located on the bedrock, the risk of seepage damage to the dam foundation caused by the deep overburden must be fully considered. For earth-rock dams built on deep overburden, dam foundation seepage monitoring is crucial.

[0004] Traditional methods for monitoring dam seepage include measuring water head with pressure tubes, measuring seepage flow with water weirs, piezometers, and water level holes. In recent years, with the continuous advancement of technology, non-destructive detection methods have gradually been applied in actual engineering, such as resistivity method, natural electric field method, transient electromagnetic method, ground penetrating radar method, isotope tracer method, and temperature tracer method. Among them, the temperature tracer method has attracted much attention in the field of seepage monitoring due to its unique advantages. This method is based on the coupling principle of seepage field and temperature field, and obtains the seepage state by measuring temperature and combining it with the corresponding mathematical model.

[0005] In the early days, the temperature tracing method mainly measured the temperature by burying a large number of thermistors at the location to be measured. In recent years, optical fiber temperature measurement technology, as an emerging monitoring technology, has been increasingly widely used in the field of rock and soil seepage monitoring due to its advantages such as corrosion resistance, anti-electromagnetic interference, low cost, long-distance distributed measurement and good durability. In particular, the distributed optical fiber temperature sensing system (DTS system for short), as a sensing system that can measure the distribution of spatial temperature field in real time, uses optical fiber as both a sensor and a signal transmission channel. The theory and technical system of using the DTS system for dam leakage monitoring are relatively mature.

[0006] The invention patent with publication number CN109856032B discloses a point heat source mobile distributed seepage monitoring system and its monitoring method, which combines optical fiber temperature sensors with point heat sources for seepage monitoring. Its principle is: insert the series point sensing heating elements into the horizontal monitoring tube; set a suitable voltage to implement heating, and when the temperature rises to the required temperature, stop heating and collect the cooling time data of each measuring point; drag the measuring point and implement multiple measurements until the entire monitoring line is covered; finally, based on the measured cooling time data and the optical fiber sensor wavelength time curve, the seepage state is identified. It has the following disadvantages:

[0007] (1) The monitoring pipe is arranged horizontally along the axial direction, which makes the construction difficult. For example, for the seepage monitoring of completed projects or deep overburden, the excavation must be carried out to the required depth before the monitoring pipe can be arranged. The burial cost is too high and the applicability is low.

[0008] (2) During the monitoring process, the heating module needs to heat the surrounding soil to a certain temperature. Since the heat generated by the heating module is continuously carried away by the seepage water or diffused to the surrounding during the heating process, in order to heat the soil to the required temperature in a short time, the heating module needs to meet a certain heating power. If there are too many sensors connected in series at this time, the required total heating power will be too high, which places high requirements on the power of the power supply system and the cable carrying capacity.

[0009] (3) The intervals between measuring points are large. If the entire monitoring line is to be covered, the measuring points need to be manually dragged and multiple measurements need to be performed. Therefore, during the monitoring process, this technology is time-consuming and difficult to achieve distributed monitoring.

[0010] (4) The gap between the sensing heating unit and the monitoring tube is filled with a liquid with good thermal conductivity. Although it can improve the heat exchange efficiency between the seepage water and the heat source, it will cause interference heat transfer between adjacent measuring points and affect the monitoring accuracy.

[0011] (5) The degree of automation is low, and automated measurement, analysis, and early warning cannot be achieved. Summary of the invention

[0012] In order to solve the problems existing in the above-mentioned background technology, the present invention proposes a distributed automatic monitoring device for dam foundation seepage based on artificial heat source, which is a quantitative analysis technology suitable for the seepage state of thick covering layers, realizes automatic monitoring and early warning of seepage of earth-rock dam foundation with thick covering layers, and reduces construction and maintenance costs.

[0013] The technical solution of the present invention to solve the above problems is: a distributed automatic monitoring device for dam foundation seepage based on artificial heat source, which is special in that:

[0014] It includes a vertical monitoring tube, a double-chamber temperature-controlled water tank, a circulation control module, and a data acquisition and early warning module.

[0015] The vertical monitoring pipe is a circular pipe with a closed bottom and an open top. The monitoring pipe is arranged vertically. In actual engineering, the monitoring pipe is arranged vertically and buried in the covering layer of soil of the dam foundation by hammering.

[0016] The dual-chamber temperature-controlled water tank and the circulation control module are used to periodically heat the water in the water tank and circulate it with the water in the vertical monitoring pipe.

[0017] The data acquisition and early warning module consists of three parts: a distributed optical fiber temperature sensor, a data processing module and an early warning module; the distributed optical fiber temperature sensor is used to measure the temperature inside the vertical monitoring tube in real time, and transmit the collected temperature data to the data processing module; the data processing module is used to receive and store the temperature data collected from the distributed optical fiber temperature sensor, and automatically calculate the seepage velocity according to the cooling curve of the vertical monitoring tube; in addition, the module includes an early warning function: when the flow velocity or cooling rate changes beyond the set threshold, a graded early warning is performed, and the early warning signal is transmitted to the alarm module, and the alarm module issues an alarm message.

[0018] Furthermore, the vertical monitoring pipe is made of a circular steel pipe.

[0019] Furthermore, in order to facilitate driving into the soil covering the dam foundation, the bottom of the vertical monitoring pipe is processed into a cone shape.

[0020] Furthermore, the above-mentioned distributed optical fiber temperature sensor includes a temperature measuring host and a temperature measuring optical fiber. The end of the temperature measuring optical fiber is inserted into the bottom of the vertical monitoring tube to collect temperature data in the monitoring tube in real time, and the other end is connected to the temperature measuring host. The temperature measuring host transmits the collected temperature data to the data processing module.

[0021] Furthermore, the data processing module includes a small computer and a corresponding data processing algorithm. The small computer receives and stores the temperature data collected from the distributed optical fiber temperature sensor, and automatically calculates the seepage velocity according to the cooling curve of the monitoring tube.

[0022] Furthermore, the alarm module includes a text message transceiver, which issues alarm information to corresponding personnel when receiving the early warning signal from the data processing module, so as to implement corresponding plans in time.

[0023] Furthermore, the above-mentioned dual-chamber temperature-controlled water tank and circulation control module includes a dual-chamber temperature-controlled water tank and a water circulation control component; the dual-chamber temperature-controlled water tank includes two water tanks, each of which is equipped with a heating device, and the heating temperature can be set as needed; the water circulation control component includes a pipeline and a two-way water pump, the upper end of the pipeline is connected to the water tank, and the lower end is connected to the bottom of the vertical monitoring tube, and a two-way water pump is arranged in the middle, which is used to inject hot water in the water tank into the vertical monitoring tube, or to draw cold water after cooling in the vertical monitoring tube into the water tank.

[0024] Furthermore, the water circulation control component further includes an electromagnetic three-way valve, which is arranged between the water tank and the water pump to control the water passage.

[0025] Furthermore, a heat-insulating layer is provided outside the water bin to prevent heat dissipation in the bin.

[0026] Advantages of the present invention:

[0027] 1. The device provided by the present invention realizes the distributed seepage monitoring of earth-rock dam projects on thick overburden. The monitoring pipe is arranged vertically and can be directly driven in by hammering, without the need for excavation. The construction is convenient and the cost is low. The device has a simple structure and is easy to maintain later.

[0028] 2. The device provided by the present invention uses a double-chamber temperature-controlled water tank to heat water in a cyclic cycle, which requires low heating power and low requirements for the power supply system. The temperature-controlled water tank is in a closed state, and the energy loss during the heating process is low; the heated water can be quickly injected into the monitoring tube in a short time, and the heat source control accuracy is high and the monitoring accuracy is good;

[0029] 3. The device provided by the present invention can realize automatic monitoring of seepage and broadcast of early warning information. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic diagram of the overall arrangement of the monitoring device provided by the present invention;

[0031] Figure 2 A schematic diagram of a data acquisition and early warning module in the monitoring device provided by the present invention;

[0032] Figure 3 This is a schematic diagram of a dual-chamber temperature-controlled water tank and a circulation control module in the monitoring device provided by the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention.

[0034] The present invention proposes an automatic monitoring device for dam foundation flow velocity based on artificial heat source, the basic structure and arrangement of which are as follows: Figure 1 As shown, the device mainly includes: a vertical monitoring tube, a double-chamber temperature-controlled water tank and a circulation control module and a data acquisition and early warning module. The vertical monitoring tube is a round tube with a closed bottom and an open top, and the monitoring tube is arranged vertically.

[0035] In some embodiments provided by the present invention, specifically, the vertical monitoring tube is made of a round (e.g., 8 cm in diameter) steel tube with a closed bottom and an open top. Figure 1 In actual engineering, the monitoring pipe is arranged vertically and buried in the covering layer of the dam foundation by hammering.

[0036] In order to facilitate insertion, the bottom of the monitoring pipe should be processed into a cone shape. The length of the monitoring pipe needs to be determined according to the monitoring depth required by the actual project. In earth-rock dam projects with deep coverage, the dam foundation seepage monitoring pipe can be arranged in the coverage layer on the downstream side of the dam body to monitor the seepage status of key parts of the dam foundation.

[0037] See also Figure 2 The data acquisition and early warning module includes three parts: a distributed optical fiber temperature sensor, a data processing module and an early warning module.

[0038] The distributed optical fiber temperature sensor comprises a temperature measuring host and a temperature measuring optical fiber, which is used to measure the temperature inside the monitoring tube in real time and transmit the collected temperature data to the data processing module.

[0039] In some embodiments provided by the present invention, specifically, the end of the temperature measuring optical fiber is inserted into the bottom of the monitoring tube to collect temperature data in the monitoring tube in real time, and the other end is connected to a temperature measuring host, and the temperature measuring host transmits the collected temperature data to a data processing module.

[0040] The data processing module is composed of a small computer and a corresponding data processing algorithm. It is used to receive and store the temperature data collected from the distributed optical fiber temperature sensor, and automatically calculate the seepage velocity according to the cooling curve of the monitoring tube. In addition, the module includes an early warning function: when the flow velocity (or cooling rate) changes beyond the set threshold, a graded early warning is issued, and the early warning signal is transmitted to the alarm module.

[0041] In some embodiments provided by the present invention, the alarm module is mainly composed of a short message transceiver. When a warning signal from a data processing module is obtained, an alarm message is issued to corresponding personnel so that corresponding plans can be implemented in a timely manner.

[0042] In some embodiments provided by the present invention, Figure 3 As shown, the dual-chamber temperature-controlled water tank and circulation control module includes two parts: a dual-chamber temperature-controlled water tank and a water circulation control component, which are used to periodically heat the water in the water tank and circulate it with the water in the monitoring tube.

[0043] Specifically, the dual-chamber temperature-controlled water tank contains two water tanks, denoted as tank A and tank B. Each tank is equipped with a heating device, and the heating temperature can be set as needed (such as 60°C); the volume of each tank must be greater than the volume of water required to fill the monitoring tube. For example, when the diameter of the monitoring tube is 8cm and the monitoring depth is 20m, the water tank capacity needs to be 0.1m 3 about.

[0044] As a preferred embodiment, a heat-insulating layer is provided outside the water bin to prevent heat dissipation in the bin.

[0045] Specifically, the water circulation control component includes a pipeline, a two-way water pump and an electromagnetic three-way valve. The upper end of the pipeline is connected to the water tank, and the lower end is connected to the bottom of the monitoring tube. A two-way water pump is arranged in the middle to inject the hot water in the water tank into the monitoring tube, or to extract the cooled cold water in the monitoring tube into the water tank. In addition, an electromagnetic three-way valve is arranged between the A tank, the B tank and the water pump to control the water passage, such as connecting "A tank-monitoring tube" or "B tank-monitoring tube". This component can automatically operate according to the required time interval (such as 6h), start the water pump, and perform water pumping and water injection circulation between the two water tanks and the monitoring tube.

[0046] A complete pumping and filling cycle is as follows:

[0047] Warehouse A is filled with water and heated to the required temperature. The electromagnetic three-way valve is controlled to connect "Warehouse A-Monitoring Tube". The water pump is started to inject the hot water in warehouse A into the monitoring tube, and the cooling process of the water in the monitoring tube is measured; after the preset time interval is reached, the water pump is started to pump the cold water in the monitoring tube back to warehouse A. After the extraction is completed, warehouse A starts heating, and switches the valve to connect "Warehouse B-Monitoring Tube", and injects the hot water in warehouse B into the monitoring tube to monitor the cooling curve. After the preset time interval is reached, the cold water in the monitoring tube is pumped back to warehouse B; warehouse B starts heating, and switches the valve to connect "Warehouse A-Monitoring Tube" for the next cycle.

[0048] The working mechanism of the dam foundation flow velocity automatic monitoring device based on artificial heat source proposed in the present invention is as follows:

[0049] In the earth-rock dam project on the deep overburden, the monitoring location and monitoring depth are selected, the prefabricated cone-head bottom-sealed monitoring tube is vertically driven into the soil layer, and the temperature measuring optical fiber and water pipe are respectively inserted into the monitoring tube. Figure 1 As shown, the optical fiber and water pipes are connected to the "data processing and early warning module" and the "double-chamber temperature-controlled water tank and circulation control module" respectively, and the automatic seepage monitoring can be started by starting the device.

[0050] The testing principle of this device is based on the coupling of seepage field and temperature field. The seepage state of the soil is quantitatively judged by measuring the temperature inside the temperature measuring tube and combining it with the theoretical model. There is a temperature difference between the hot water in the monitoring tube and the surrounding soil. Under the action of seepage in the soil, the heat in the monitoring tube will be transferred to the surrounding by heat conduction and heat convection, and the water temperature in the tube will gradually decrease. When there is no seepage in the soil or the seepage rate is low, the temperature drop rate in the tube is slow; as the seepage rate in the soil increases, the temperature drop rate in the tube changes. Based on this principle, abnormal seepage conditions can be judged, and the seepage rate in the soil can be quantitatively evaluated according to the cooling curve.

[0051] This device uses the above principle to periodically inject hot water into the monitoring pipe according to a predetermined program, uses a distributed optical fiber temperature sensor to record the cooling process of the water in the pipe, and then determines the seepage state and calculates the seepage velocity based on the cooling curve. When abnormal seepage occurs, the alarm module is activated and the monitoring warning information is sent to relevant personnel to achieve early warning.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art can still adjust the technical solutions described in the above embodiments or replace some of the technical features by equivalents. Therefore, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A distributed automatic monitoring device for dam foundation seepage based on artificial heat source, characterized in that: It includes vertical monitoring tube, double-chamber temperature-controlled water tank, circulation control module and data acquisition and early warning module; The vertical monitoring tube is a round tube with a closed bottom and an open top, and the monitoring tube is arranged vertically; The dual-chamber temperature-controlled water tank and the circulation control module are used to periodically heat the water in the water tank and circulate it with the water in the vertical monitoring tube; The data acquisition and early warning module consists of three parts: a distributed optical fiber temperature sensor, a data processing module and an early warning module; The distributed optical fiber temperature sensor is used to measure the temperature inside the vertical monitoring tube in real time and transmit the collected temperature data to the data processing module; The data processing module is used to receive and store temperature data collected from distributed optical fiber temperature sensors, and automatically calculate the seepage velocity based on the cooling curve of the vertical monitoring tube; in addition, the module includes an early warning function: when the flow velocity or cooling rate changes beyond a set threshold, a graded early warning is performed, and the early warning signal is transmitted to the alarm module, which issues an alarm message.

2. The distributed automatic monitoring device for dam foundation seepage based on artificial heat source according to claim 1 is characterized by: The vertical monitoring pipe is made of a circular steel pipe.

3. The distributed automatic monitoring device for dam foundation seepage based on artificial heat source according to claim 2 is characterized by: The bottom of the vertical monitoring pipe is processed into a cone shape.

4. A distributed automatic monitoring device for dam foundation seepage based on artificial heat source according to any one of claims 1 to 3, characterized in that: The distributed optical fiber temperature sensor includes a temperature measuring host and a temperature measuring optical fiber. The end of the temperature measuring optical fiber is inserted into the bottom of a vertical monitoring tube to collect temperature data in the monitoring tube in real time. The other end is connected to the temperature measuring host, and the temperature measuring host transmits the collected temperature data to a data processing module.

5. The distributed automatic monitoring device for dam foundation seepage based on artificial heat source according to claim 4 is characterized by: The data processing module includes a small computer and a corresponding data processing algorithm.

6. The distributed automatic monitoring device for dam foundation seepage based on artificial heat source according to claim 5 is characterized by: The alarm module includes a short message transceiver, and when the early warning signal from the data processing module is obtained, the alarm information is issued.

7. The distributed automatic monitoring device for dam foundation seepage based on artificial heat source according to claim 6 is characterized by: The dual-chamber temperature-controlled water tank and circulation control module includes a dual-chamber temperature-controlled water tank and a water circulation control component; The dual-chamber temperature-controlled water tank includes two water tanks, each of which is equipped with a heating device, and the heating temperature can be set as required; The water circulation control component includes a pipeline and a two-way water pump. The upper end of the pipeline is connected to the water tank, and the lower end is connected to the bottom of the vertical monitoring tube. A two-way water pump is arranged in the middle to inject the hot water in the water tank into the vertical monitoring tube, or to extract the cooled cold water in the vertical monitoring tube into the water tank.

8. The distributed automatic monitoring device for dam foundation seepage based on artificial heat source according to claim 7 is characterized by: The water circulation control component also includes an electromagnetic three-way valve, which is arranged between the water tank and the water pump and is used to control the water passage.

9. The distributed automatic monitoring device for dam foundation seepage based on artificial heat source according to claim 8, characterized in that: A heat preservation layer is arranged outside the water bin to prevent heat dissipation in the bin.

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