On-line monitoring device and method for sand content of effluent of precipitation well based on laser scattering

Abstract

The invention relates to the technical field of foundation pit dewatering, and particularly discloses a dewatering well effluent sand content online monitoring device and method based on laser scattering, the dewatering well effluent sand content online monitoring device comprises a test bin provided with a water inlet and a water outlet, a monitoring probe located in the test bin and a control unit connected with the monitoring probe, and the water inlet is communicated with a dewatering well through a water delivery branch pipe; the monitoring probe is used for monitoring water flow entering the testing bin and transmitting monitoring data to the control unit, and the controller is used for calculating the sand content of the water flow; the device can integrate dynamic sampling, online analysis and intelligent calibration, so as to solve the technical problems of high precision, wide range (0.001%-10%) and collaborative optimization of anti-interference capability. The light-proof design of the test bin is matched with a dustproof sealing ring, so that the interference of ambient light is thoroughly eliminated, the test bin adapts to the severe environment of dust raising of a foundation pit, and the test precision is greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of foundation pit dewatering technology, and more specifically, to an on-line monitoring device and method for the sand content rate of the water discharged from a dewatering well based on laser scattering. Background Art

[0002] In the foundation pit dewatering project, the precise control of the sand content in the water discharged from the dewatering well is the core link to ensure the safety of the project. If the sand content exceeds the design threshold, it may cause problems such as differential foundation settlement and attenuation of dewatering efficiency, which will further threaten the structural stability of adjacent structures. Therefore, the real-time monitoring of the sand content rate is not only used to evaluate the impact of groundwater pumping on the stratum, but also provides key data support for dynamically adjusting the dewatering plan to avoid the risk of clogging of the seepage channel or soil erosion caused by the migration of sand particles.

[0003] At present, the commonly used sand content rate detection technologies in engineering have significant limitations:

[0004] Although the volumetric method is easy to operate, it relies on manual sampling and static separation. In the low sand content rate range (such as one in one hundred thousand to one in two hundred thousand), limited by the sample volume and separation efficiency, it is difficult to achieve high-precision continuous monitoring; the gravimetric method requires the use of precise laboratory instruments, has a long measurement period and cannot adapt to complex on-site working conditions, especially the sensitivity to micro sand particles (<0.01%) is insufficient; the specific gravity method is easily interfered by the ion composition and colloidal substances in groundwater, and the error increases significantly when there is more hard water or fine particle suspensions, making it difficult to meet the real-time feedback requirements of the project.

[0005] The existing technologies generally have the defects of offline detection lag and insufficient on-site adaptability, resulting in difficulty in timely detecting abnormal fluctuations (such as sudden increase or sudden decrease) of the sand content rate during the construction process and being unable to effectively warn of potential risks. Therefore, there is an urgent need for an on-line monitoring device and method for the sand content rate of the water discharged from a dewatering well based on laser scattering, which can integrate a detection device with dynamic sampling, on-line analysis and intelligent calibration to solve the technical problems of coordinated optimization of high precision, wide range (0.001% - 10%) and anti-interference ability. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an on-line monitoring device and method for the sand content rate of the water discharged from a dewatering well based on laser scattering;

[0007] The solution adopted by the present invention to solve the technical problem is:

[0008] An on-line monitoring device for the sand content rate of the water discharged from a dewatering well based on laser scattering, comprising a test chamber provided with an inlet and an outlet, a monitoring probe located in the test chamber, and a control unit connected to the monitoring probe, wherein the inlet is communicated with the dewatering well through a water delivery branch pipe;

[0009] The monitoring probe monitors the water flow entering the test chamber and transmits the monitoring data to the control unit, and the controller calculates the sand content rate of the water flow.

[0010] A laser emitter and a laser receiver, which are respectively connected to the control unit, are arranged in the monitoring probe.

[0011] In some possible implementation manners, a flowmeter for detecting the water flow rate in the water delivery branch pipe and a control valve for controlling the water flow rate are arranged on the water delivery branch pipe.

[0012] In some possible implementation manners, the test chamber is cylindrical, the water inlet is arranged at the top of the test chamber and its axis is coaxial with the axis of the test chamber; the laser beam emitted by the monitoring probe is perpendicular to the axis of the test chamber.

[0013] In some possible implementation manners, the water outlet is arranged at the bottom of the test chamber, and a precipitation well is provided with a main drain pipe, and the main drain pipe is respectively communicated with the water delivery branch pipe and the water outlet.

[0014] In some possible implementation manners, the test chamber is made of light-tight materials, and an observation window for observing the water flow condition is arranged on the test chamber.

[0015] In some possible implementation manners, the laser emitter is a 650nm semiconductor laser, the laser receiver is a 120° wide-angle scattered light receiver, the light source power is 10mW, and the detection accuracy is ±0.5% FS.

[0016] In some possible implementation manners, a support frame for supporting the test chamber is further included.

[0017] In some possible implementation manners, it specifically includes the following steps:

[0018] Step S1: Control the water flow rate in the water delivery branch pipe to be 1 - 3 L / min and flow into the test chamber through the water inlet;

[0019] Step S2: The monitoring probe emits a laser beam to penetrate the water flow, interacts with the sand and / or clay in the water flow, generates a scattering phenomenon, and the scattered light is transmitted to the control unit through the laser receiving end;

[0020] Step S3: The control unit obtains the sand content rate through the particle concentration, the scattered light intensity, and the particle size.

[0021] In some possible implementation manners, step S3 specifically includes the following steps:

[0022] Step S31: The control unit converts the scattered light optical signal into an electric current signal and measures the scattered light intensity and the scattering angle of the suspended particles:

[0023] Step S32: Invert the particle size distribution using the Tikhonov regularization algorithm;

[0024] Step S33: Calculate the sand content rate in combination with the reference density; the reference density is 2.65 g / cm3.

[0025] In some possible implementation manners, the sand content rate adopts a piecewise calculation formula:

[0026] When d < 0.075 mm: S = 0.22C·d -0.35 ;

[0027] When d ≥ 0.075 mm: S = 0.17C·d 0.41 ;

[0028] Wherein, S is the sand content rate, C is the particle concentration, and d is the median particle size.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] The present invention can integrate a detection device for dynamic sampling, on-line analysis and intelligent calibration to solve the technical problems of collaborative optimization of high precision, wide measurement range (0.001% - 10%) and anti-interference ability;

[0031] The light-tight design of the test chamber of the present invention is combined with a dust-proof sealing ring to completely eliminate the interference of ambient light, adapt to the harsh environment of foundation pit dust, and greatly improve the test accuracy; avoid the excessive drainage of sand grains from causing formation settlement. Brief Description of the Drawings

[0032] Figure 1 It is a structural schematic diagram of the present invention;

[0033] Wherein: 1. Test chamber; 2. Monitoring probe; 3. Water delivery branch pipe; 31. Control valve; 32. Flowmeter; 4. Support frame; 5. Control module; 6. Power supply module; 7. Probe support; 71. PVC pipe; 10. Main drain pipe. Detailed Embodiments

[0034] In the present invention, unless otherwise clearly specified and defined, terms such as "installation", "connection", "linkage", "fixation" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two components or the interaction relationship between two components. The "first", "second" and similar words mentioned in this application do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "a" or "one" do not indicate a quantity limitation, but indicate that there is at least one. In the implementation of this application, "and / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In the description of the embodiments of this application, unless otherwise stated, the meaning of "a plurality" refers to two or more. For example, a plurality of positioning posts means two or more positioning posts. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] The present invention will be described in detail below.

[0036] As Figure 1 shown, an on-line monitoring device for the sand content rate of the water discharged from a precipitation well based on laser scattering includes a test chamber 1 provided with a water inlet and a water outlet, a monitoring probe 2 located in the test chamber 1, and a control unit connected to the monitoring probe 2. The water inlet is communicated with the precipitation well through a water delivery branch pipe 3;

[0037] The monitoring probe 2 monitors the water flow entering the test chamber 1 and transmits the monitoring data to the control unit, and the controller calculates the sand content rate of the water flow;

[0038] A laser transmitter and a laser receiver respectively connected to the control unit are arranged in the monitoring probe 2;

[0039] The control unit includes a control module 5, an early warning module and a communication module connected to the control module 5; the control module 5 is respectively connected to the laser transmitter and the laser receiver; the communication module is externally connected to a terminal; the early warning module triggers an early warning reminder when the sand content rate does not meet the requirements; the control module 5 is externally connected to a power supply module 6 and is powered through the power supply module 6. The power supply module 6 includes a solar panel and an energy storage system connected to the solar panel;

[0040] Preferably, the controller integrates an STM32 microprocessor and is built-in with a dynamic calibration algorithm based on Mie scattering theory, supporting the detection of the sand content rate in the range of 0.001% to 10%;

[0041] The communication module is equipped with 4G / NB-IoT dual-mode communication, which uploads data to the cloud platform in real time and supports threshold warning (such as sand content > 0.001% triggers an alarm).

[0042] The solar panel is a 100W monocrystalline silicon component with an adjustable tilt angle and a daily power generation of ≥500Wh; the energy storage system is a 12V / 200Ah colloid battery pack equipped with a charge and discharge controller, supporting wide-temperature operation from -20°C to 60°C;

[0043] Power management module: realizes automatic switching between solar and mains dual-power supply to ensure the system runs uninterruptedly for 7×24 hours;

[0044] When the power supply module 6 uses grid power supply, it also includes a power management module to realize automatic switching between solar and mains dual-power supply to ensure the system runs uninterruptedly for 7×24 hours.

[0045] In some possible implementation manners, a flow meter 32 for detecting the water flow rate in the water delivery branch pipe 3 and a control valve 31 for controlling the water flow rate are provided on the water delivery branch pipe 3.

[0046] When detecting the sand content of the water flow, the water flow enters the test chamber 1 through the water delivery branch pipe 3 and flows downward under the action of gravity in the test chamber 1; the flow rate of the water flow in the test chamber 1 is monitored through the settings of the flow meter 32 and the control valve 31; the test accuracy is higher; specifically, the inlet and outlet are externally connected with DN400 pipes; the water flow rate in the water delivery branch pipe 3 is 1 - 3L / min, so that the water flow is stable without bubbles; the influence of bubbles on the test accuracy is reduced;

[0047] In some possible implementation manners, the test chamber 1 is cylindrical, the inlet is arranged at the top of the test chamber 1 and its axis is coaxial with the axis of the test chamber 1; the laser beam emitted by the monitoring probe 2 is perpendicular to the axis of the test chamber 1; a probe support 7 for installing the probe is arranged outside the test chamber 1; the probe support 7 includes a support body located outside the test chamber 1 and a PVC wire pipe vertically arranged and connected to the support body; one end of the PVC pipe 71 passes through the top of the test chamber 1 and is located inside the test chamber 1; the detection probe is installed at one end of the PVC pipe 71 extending into the test chamber 1; the PVC pipe 71 is in sealed cooperation with the test chamber 1;

[0048] According to the Mie scattering principle, when the incidence is perpendicular, the scattering angle is set to 120°, which is convenient for standardizing the calculation of the particle size distribution and concentration. The probe support 7 is fixed on the central axis of the test chamber 1 and is perpendicular to the incidence, so that the angle deviation compensation does not need to be considered during the calibration process, reducing the operation complexity; the perpendicular incidence avoids the possible particle motion blur effect (such as the optical path change caused by the water flow velocity of the particles) when the laser beam is parallel to the water flow direction, ensuring the stability of the scattering signal.

[0049] In some possible embodiments, the test chamber 1 is provided at the bottom of the water outlet, and the precipitation well is provided with a main drain pipe 10, and the main drain pipe 10 is respectively communicated with the water delivery branch pipe 3 and the water outlet; with this setting, the water flows through the water delivery branch pipe 3 and flows vertically downward under gravity from top to bottom. The monitoring probe 2 is located in the middle of the test chamber 1. When the water flow passes through the monitoring probe 2, the laser beam emitted by the monitoring probe 2 will pass through the water flow and interact with the particulate matter in the water flow, generating a scattering phenomenon.

[0050] In some possible embodiments, the test chamber 1 is made of a light-tight material. Preferably, black ABS engineering plastic is used to isolate the influence of external light interference on the detection accuracy; an observation window for observing the water flow condition is provided on the test chamber 1.

[0051] In some possible embodiments, the laser emitter is a 650 nm semiconductor laser, the laser receiver is a 120° wide-angle scattered light receiver, the light source power is 10 mW, and the detection accuracy is ±0.5% FS.

[0052] In some possible embodiments, a support frame 4 for supporting the test chamber 1 is further included.

[0053] The monitoring method of the on-line sand content monitoring device for the precipitation well water outlet based on laser scattering specifically includes the following steps:

[0054] Control the water flow rate in the water delivery branch pipe 3 to be 1 - 3 L / min and flow into the test chamber 1 through the water inlet.

[0055] The monitoring probe 2 emits a laser beam to penetrate the water flow and interact with the sand and / or clay in the water flow, generating a scattering phenomenon. The scattered light is transmitted to the control unit through the laser receiving end.

[0056] The scattering follows the Mie scattering theory, and the scattered light intensity satisfies a functional relationship with the particle size, the incident laser wavelength, and the particle concentration.

[0057] Among them, I(θ) is the scattered light intensity, θ is the scattering angle, the function f characterizes the influence characteristics of the particle size distribution on the spatial distribution of the scattered light, C is the concentration, and λ is the incident laser wavelength.

[0058] The control unit obtains the sand content rate based on the particle concentration, scattered light intensity, and particle size; specifically, it includes the following steps:

[0059] The control unit converts the scattered light optical signal into an electric current signal, measures the scattered light intensity of suspended particles and the scattering angle: uses the Tikhonov regularization algorithm to invert the particle size distribution;

[0060] Combined with the reference density to calculate the sand content rate; the reference density is 2.65 g / cm3.

[0061] The sand content rate adopts a piecewise calculation formula:

[0062] When d < 0.075 mm: S = 0.22C·d -0.35 ;

[0063] When d ≥ 0.075 mm: S = 0.17C·d 0.41 ;

[0064] Wherein, S is the sand content rate, C is the particle concentration, and d is the median particle size.

[0065] Step S4: The control module 5 transmits the sand content rate data to the terminal and determines whether the sand content rate meets the requirements. If not, the control module 5 controls the warning module to give a warning reminder; for example, when the sand content rate > 0.001%, the control module 5 controls the warning module to trigger an alarm.

[0066] This device has a millisecond-level response speed and supports continuous monitoring of the circulating water flow of the dynamic sampling unit. And the laser scattering module has been widely used in industrial water quality monitoring (such as sewage treatment), with mature technology and controllable costs. The measurement principle of this device is simple, which can effectively improve the measurement efficiency of the sand content rate, save time and energy. After being calibrated with ISO12103 - A2 standard sand samples, it can directly output the sand content rate monitoring data that meets the requirements of the "Technical Specification for Building Foundation Pit Support" JGJ120 - 2012.

[0067] The present invention is not limited to the foregoing specific embodiments. The present invention extends to any new feature or any new combination disclosed in this specification, as well as any new method or process step or any new combination disclosed.

Claims

1. An on-line monitoring device for sand content in the water discharged from a precipitation well based on laser scattering, characterized in that, It includes a test chamber provided with a water inlet and a water outlet, a monitoring probe located inside the test chamber, and a control unit connected to the monitoring probe. The water inlet is communicated with a precipitation well through a water conveyance branch pipe. The monitoring probe monitors the water flow entering the test chamber and transmits the monitoring data to the control unit. The controller calculates the sand content rate of the water flow. A laser emitter and a laser receiver, which are respectively connected to the control unit, are arranged inside the monitoring probe.

2. The on-line monitoring device for sand content in the water discharged from a precipitation well based on laser scattering according to claim 1, characterized in that A flowmeter for detecting the water flow rate in the water conveyance branch pipe and a control valve for controlling the water flow rate are arranged on the water conveyance branch pipe.

3. The on-line monitoring device for sand content in the water discharged from a precipitation well based on laser scattering according to claim 1, characterized in that, The test chamber is cylindrical. The water inlet is arranged at the top of the test chamber and its axis is coaxial with the axis of the test chamber. The laser beam emitted by the monitoring probe is perpendicular to the axis of the test chamber.

4. The on-line monitoring device for sand content in the water discharged from a precipitation well based on laser scattering according to claim 3, wherein The water outlet is arranged at the bottom of the test chamber. The precipitation well is provided with a main drainage pipe, and the main drainage pipe is communicated with the water conveyance branch pipe and the water outlet respectively.

5. The on-line monitoring device for sand content in the water discharged from a precipitation well based on laser scattering according to claim 1, characterized in that The test chamber is made of light-proof material, and an observation window for observing the water flow condition is arranged on the test chamber.

6. The online monitoring device for sand content in the water discharged from a precipitation well based on laser scattering according to claim 1, characterized in that, The laser emitter is a 650nm semiconductor laser, the laser receiver is a 120° wide-angle scattered light receiver, the light source power is 10mW, and the detection accuracy is ±0.5%FS.

7. The on-line monitoring device for sand content in the water discharged from a precipitation well based on laser scattering according to any one of claims 1-6, characterized in that, It also includes a support frame for supporting the test chamber.

8. A monitoring method for an on-line monitoring device of the sand content in the water discharged from a precipitation well based on laser scattering according to any one of claims 1-7, characterized in that, Specifically, it includes the following steps: Step S1: Control the water flow rate in the water conveyance branch pipe to be 1 - 3L / min and flow into the test chamber through the water inlet. Step S2: The monitoring probe emits a laser beam to penetrate the water flow, interact with sand and / or clay in the water flow, generate a scattering phenomenon, and the scattered light is transmitted to the control unit through the laser receiving end. Step S3: The control unit obtains the sand content rate through the particle concentration, scattered light intensity, and particle size.

9. The method of the online monitoring device for the sand content rate of the water output of a precipitation well based on laser scattering according to claim 8, wherein, The specific steps of Step S3 are as follows: Step S31: The control unit converts the scattered light optical signal into an electric current signal and measures the scattered light intensity of the suspended particles and the scattering angle. Step S32: Invert the particle size distribution by using the Tikhonov regularization algorithm. Step S33: Calculate the sand content rate in combination with the reference density; the reference density is 2.65g / cm3.

10. The method of the online monitoring device for the sand content rate of the water discharged from the precipitation well based on laser scattering according to claim 9, characterized in that, The sand content rate adopts a segmented calculation formula: When d < 0.075 mm: S = 0.22C·d -0.35 ; When d ≥ 0.075 mm: S = 0.17C·d 0.41 ; Among them, S is the sand content rate, C is the particle concentration, and d is the median particle size.

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