A monitoring and early warning system for soil-bentonite diaphragm walls

Abstract

The application relates to the technical field of underground pollution prevention and control construction, and discloses a monitoring and early warning system for a soil-bentonite isolation wall. The system comprises a support frame, a monitoring device and a data processing module. The support frame comprises a first vertical pipe and a second vertical pipe, which are respectively arranged inside the isolation wall and on the side of the isolation wall away from the pollutants. The monitoring device comprises a main monitoring module arranged on the first vertical pipe and an auxiliary monitoring module arranged on the second vertical pipe. The main monitoring module is used for collecting the strain and pore pressure of each monitoring point inside the isolation wall in real time during the construction of the isolation wall, and is also used for collecting the resistivity and water content of each monitoring point inside the isolation wall in real time after the construction of the isolation wall is completed. The auxiliary monitoring module is used for collecting the water level on the outflow side of the isolation wall and the TDS value of each monitoring point in real time after the construction of the isolation wall is completed. The data processing module is used for early warning analysis of the isolation wall according to the collected data. The application can provide real-time monitoring and timely early warning for the isolation wall.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of underground pollution prevention and control construction, and particularly relates to a monitoring and early warning system for a soil-bentonite system isolation wall. BACKGROUND

[0002] When developing mineral resources, tailings generated in the smelting process can be stored in a tailings pond, but the tailings pond will pollute groundwater and the surrounding environment. The pollution range of these sites is large, and the form of pollutants is complex. Vertical isolation wall technology is widely used in various underground pollution prevention and control projects due to its strong site adaptability and excellent pollution prevention and control performance. At present, according to the different types of materials, the common isolation walls can be divided into soil-bentonite system isolation wall, plastic concrete isolation wall, cement-bentonite system isolation wall, ordinary concrete isolation wall, geomembrane-bentonite composite isolation wall, artificial frozen soil, steel sheet pile isolation wall, etc. Among them, the soil-bentonite system vertical isolation wall is one of the most common types of vertical isolation walls in underground pollution prevention and control projects due to its simple construction and low cost.

[0003] Since the degradation of pollutants in the natural state is very slow, when the isolation wall blocks the pollutants in situ, it is required to have a long service life. The Chinese invention patent with the application number 202111209281.8 discloses a structure and construction method of an activated carbon improved soil-bentonite vertical pollution prevention isolation wall. The structural strength and pollution prevention performance of the soil-bentonite vertical pollution prevention isolation wall are improved by improving the isolation material, thereby prolonging the service life thereof. However, in actual engineering applications, the improved soil-bentonite system vertical isolation wall still has the problem of weak corrosion resistance. Long-term exposure to chemical effects can easily lead to performance degradation. At the same time, affected by external factors such as complex geological conditions and construction quality, the service time of the isolation wall obtained by theoretical calculation still has uncertainty, which will directly affect the quality and safety of the surrounding water and soil environment. Therefore, how to monitor the performance state of the isolation wall in real time and provide timely early warning is an urgent problem to be solved in the service process of the soil-bentonite system isolation wall. SUMMARY

[0004] To solve the technical problem that it is difficult to provide real-time monitoring and timely early warning for the soil-bentonite system isolation wall in the service process in the prior art, the present application provides a monitoring and early warning system for a soil-bentonite system isolation wall.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0006] The present application discloses a monitoring and early warning system for a soil-bentonite system isolation wall, which comprises a support frame, a monitoring device and a data processing module.

[0007] The support frame comprises a first vertical pipe and a second vertical pipe; the first vertical pipe is arranged at the central axis position inside the isolation wall, and the second vertical pipe is arranged at the side of the isolation wall away from the pollution source, i.e. the outflow side; the first vertical pipe and the second vertical pipe are both provided with a plurality of monitoring points along the depth direction, and the monitoring points on the two vertical pipes are one-to-one corresponding and have the same depth.

[0008] The monitoring device comprises a main monitoring module arranged on the first vertical pipe and an auxiliary monitoring module arranged on the second vertical pipe; the main monitoring module is used for collecting the strain and pore pressure of each monitoring point inside in real time during the construction of the isolation wall, and is also used for collecting the resistivity and water content of each monitoring point inside in real time after the construction of the isolation wall is completed; the auxiliary monitoring module is used for collecting the water level of the outflow side of the isolation wall and the TDS value of each monitoring point in real time after the construction of the isolation wall is completed.

[0009] The data processing module is used for: a. sending the strain and pore pressure of each monitoring point inside during the construction of the isolation wall to an interactive terminal for feedback to adjust the on-site environmental conditions during the construction; b. calculating the resistivity change ratio according to the real-time resistivity of each monitoring point, and generating a first early warning signal when the resistivity change ratio of any monitoring point exceeds a preset first change ratio threshold; c. correcting the wall permeability coefficient according to the real-time water content of each monitoring point, and calculating the permeability coefficient change ratio, and generating a second early warning signal when the permeability coefficient change ratio of any monitoring point exceeds a preset second change ratio threshold; d. judging whether the water level of the outflow side of the isolation wall exceeds a preset water level threshold, and generating a third early warning signal if yes; e. calculating the TDS value change ratio according to the real-time TDS value of each monitoring point when the change amplitude of the water level per unit time exceeds the fluctuation range of the background value of the underground water level of the site, and generating a fourth early warning signal when the TDS value change ratio of any monitoring point exceeds a preset third change ratio threshold.

[0010] As a further improvement of the above-mentioned scheme, the main monitoring module comprises a plurality of groups of first data acquisition components distributed along the depth direction, and the auxiliary monitoring module comprises a plurality of groups of second data acquisition components distributed along the depth direction; the number of the first data acquisition components and the second data acquisition components corresponds one-to-one and is respectively arranged at the corresponding monitoring points; each group of first data acquisition components comprises a strain sensor, a pore pressure sensor, a resistivity probe and a TDR sensor, which are respectively used for collecting the strain, pore pressure, resistivity and water content of the corresponding monitoring point; each group of second data acquisition components comprises a TDS sensor for collecting the TDS value of the corresponding monitoring point; the auxiliary monitoring module further comprises a water level monitoring float for collecting the water level of the outflow side of the isolation wall.

[0011] As a further improvement of the above-mentioned scheme, the calculation formula of the resistivity change ratio according to the real-time resistivity of each monitoring point is:

[0012] N1 = | p0 - p i | / p0

[0013] In the formula, N1 is the resistivity variation ratio of a monitoring point; p0 is the resistivity reference value collected by the resistivity probe at the monitoring point within a preset period after the completion of the construction of the isolation wall; p is the real-time resistivity collected by the resistivity probe at the monitoring point. i

[0014] As a further improvement of the above scheme, the calculation formula of the wall permeability coefficient according to the real-time water content of each monitoring point is:

[0015]

[0016] In the formula, k is the permeability coefficient; FSI is the free swelling coefficient; e is the porosity; ω is the real-time water content of a monitoring point; A and B are constants fitted according to the bentonite material.

[0017] The calculation formula of the permeability coefficient variation ratio is:

[0018] M1 = | k0 - k i | / k0

[0019] In the formula, M1 is the permeability coefficient variation ratio of a monitoring point; ω0 is the water content reference value collected by the TDR sensor at the monitoring point within a preset period after the completion of the construction of the isolation wall; k0 is the wall permeability coefficient corrected by ω0; k is the wall permeability coefficient corrected by the real-time water content of the monitoring point. i

[0020] As a further improvement of the above scheme, the calculation formula of the TDS value variation ratio according to the real-time TDS value of each monitoring point is:

[0021] P1 = | C0 - C i | / C0

[0022] In the formula, P1 is the TDS value variation ratio of a monitoring point; C0 is the TDS value reference value collected by the TDS sensor at the monitoring point within a preset period after the completion of the construction of the isolation wall; C is the real-time TDS value collected by the TDS sensor at the monitoring point. i

[0023] ​​​As a further improvement of the above scheme, at each monitoring point of the first vertical pipe, the strain sensor, the pore pressure sensor, the resistivity probe and the TDR sensor are circumferentially distributed in the same horizontal plane and fixedly connected with the outer edge of the first vertical pipe; the second vertical pipe comprises an outer pipe and an inner pipe coaxially arranged and forming a sandwich, and the water level monitoring float is arranged in the sandwich, the outer pipe is uniformly provided with a plurality of through holes in communication with the sandwich, and the outer pipe is wrapped with geotextile on the outside, and at each monitoring point of the second vertical pipe, the TDS sensor is fixedly connected with the geotextile on the outside of the second vertical pipe.

[0024] As a further improvement of the above scheme, the support frame further comprises a horizontal pipe; the horizontal pipe is horizontally arranged at the top of the guide wall on both sides of the isolation wall, and the top of the first vertical pipe and the top of the second vertical pipe are fixedly connected with the horizontal pipe and form a T-shaped structure perpendicular to the construction direction of the isolation wall.

[0025] As a further improvement of the above scheme, the bottom of the first vertical pipe and the bottom of the second vertical pipe are anchor ends, and the depth of the anchor end is greater than the depth of the bottom of the isolation wall.

[0026] As a further improvement of the above scheme, a plurality of groups of support frames are provided, and the plurality of groups of support frames are sequentially distributed along the construction direction of the isolation wall; the number of monitoring devices is the same as and one-to-one corresponds to the number of support frames.

[0027] As a further improvement of the above scheme, the number of monitoring points in each group of monitoring devices is not less than five, the spacing between adjacent monitoring points increases with the increase of the depth, and a monitoring point is arranged at the interface between the permeable layer and the impermeable layer in the soil; when the construction direction of the isolation wall is a straight line, the number of support frames is not less than three, and the horizontal spacing between adjacent support frames is not greater than 15m; when the construction direction of the isolation wall is not a straight line, a support frame is arranged at the turning point, and the support frames at other straight lines still refer to the setting principle of the straight line construction direction.

[0028] Compared with the prior art, the beneficial effects of the present application are:

[0029] The present application sets up a support frame capable of installing a monitoring device inside and on the outflow side of the soil-bentonite isolation wall, and uses a remotely set data processing module to collect, process and transmit the data reflecting multiple indexes of the isolation wall. On the one hand, by monitoring the condition of the isolation wall during construction, the operating personnel can adjust the environmental conditions such as temperature, humidity and wind speed to meet the construction requirements, provide basis and intervention for the construction of the isolation wall, and ensure the construction quality. On the other hand, by evaluating the performance state of the isolation wall during service, a warning signal is generated in time, which is helpful for timely analyzing the causes of the phenomenon and formulating corresponding treatment measures, and has important engineering significance. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The monitoring and early warning system architecture diagram of the soil-bentonite type isolation wall in the embodiment 1 of the present application.

[0031] Figure 2 The cross-sectional view of the monitoring and early warning system installation in the soil-bentonite type isolation wall in the embodiment 1 of the present application (the arrow in the figure is the flow direction of the underground water).

[0032] Figure 3 The perspective structure diagram of the support frame in the embodiment 1 of the present application. Figure 2

[0033] Figure 4 The top view installation diagram of the first vertical pipe and the first data acquisition assembly in the embodiment 1 of the present application.

[0034] Figure 5 The top view installation diagram of the second vertical pipe and the second data acquisition assembly in the embodiment 1 of the present application.

[0035] Figure 6 The top view distribution diagram of the support frame when the construction direction of the isolation wall is right angle in the embodiment 2 of the present application.

[0036] In the figure: 1, support frame; 11, first vertical pipe; 12, second vertical pipe; 13, horizontal pipe; 2, monitoring device; 21, first data acquisition assembly; 211, strain sensor; 212, pore pressure sensor; 213, resistivity probe; 214, TDR sensor; 22, second data acquisition assembly; 221, TDS sensor; 23, water level monitoring float; 3, isolation wall; 4, guide wall; 5, permeable layer; 6, impermeable layer; 7, overburden layer; 8, underground water. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0038] Embodiment 1

[0039] Please refer to Figures 1-5 , the present embodiment provides a monitoring and early warning system of soil-bentonite type isolation wall, comprising: support frame 1, monitoring device 2 and data processing module.

[0040] ​The support frame 1 comprises a first vertical pipe 11 and a second vertical pipe 12, and can further comprise a horizontal pipe 13; the first vertical pipe 11 is arranged at a central axis position inside the isolation wall 3, and the second vertical pipe 12 is arranged at a side of the isolation wall 3 away from the pollution source, i.e. an outflow side; the first vertical pipe 11 and the second vertical pipe 12 are both provided with a plurality of monitoring points in the depth direction, and the monitoring points on the two vertical pipes correspond one by one and have the same depth. The horizontal pipe 13 is horizontally arranged at the top of the guide wall 4 on both sides of the isolation wall 3, and the top of the first vertical pipe 11 and the top of the second vertical pipe 12 are fixedly connected with the horizontal pipe 13, and form a “T” shaped structure whose plane is perpendicular to the construction direction of the isolation wall 3. The bottom of the first vertical pipe 11 and the bottom of the second vertical pipe 12 are both anchor ends, and the depth of the anchor end is greater than the depth of the bottom of the isolation wall 3. It should be noted that the support frame 1 can be designed to be thin and narrow to reduce the influence on the flowability of the isolation wall 3.

[0041] A plurality of support frames 1 are arranged, and the plurality of support frames 1 are sequentially distributed along the construction direction of the isolation wall 3; the number of the monitoring devices 2 is the same as that of the support frames 1 and corresponds one by one.

[0042] The construction direction of the isolation wall 3 can be a straight line, the support frame 1 is provided with not less than three groups, and the horizontal spacing between adjacent support frames 1 is not greater than 15 m. The number of monitoring points in each group of monitoring devices 2 is not less than five, the spacing between adjacent monitoring points increases with the increase of the depth, and a monitoring point is arranged at the interface between the water-permeable layer 5 and the water-resistant layer 6 in the soil. In this embodiment, the construction thickness of the isolation wall 3 is 0.6 m, the total length is 50 m, the depth of the water-permeable layer 5 reaches 19 m, and a total of seven vertical points are arranged. The seven groups of data acquisition modules 211 of each monitoring assembly 21 are arranged at depths of 0 m, 1 m, 3 m, 6 m, 9 m, 14 m and 19 m underground, respectively, and the horizontal spacing between adjacent support devices 1 is 10 m.

[0043] The monitoring device 2 comprises a main monitoring module arranged on the first vertical pipe 11 and an auxiliary monitoring module arranged on the second vertical pipe 12.

[0044] The main monitoring module is used for real-time acquisition of the strain and pore pressure of each monitoring point inside the isolation wall 3 during construction of the isolation wall 3, and is also used for real-time acquisition of the resistivity and water content of each monitoring point inside the isolation wall 3 after construction of the isolation wall 3 is completed. The strain refers to the stress change at a certain position inside the isolation wall 3; the pore pressure refers to the water pressure at a certain pore inside the isolation wall 3; the resistivity refers to the resistance value at a certain position inside the isolation wall 3; and the water content refers to the volume water content at a certain position inside the isolation wall 3, and the water content can be obtained by conversion.

[0045] The auxiliary monitoring module is used to collect the water level of the outflow side of the isolation wall 3 and the TDS value of each monitoring point in real time after the construction of the isolation wall 3 is completed. The TDS (Total Dissolved Solids) refers to the total amount of dissolved substances in water, including calcium, magnesium, sodium, potassium ions and some organic and inorganic substances. These substances exist in the form of ions or molecules in water and affect the taste, color and turbidity of water. Generally, high TDS may be an indication of water pollution, which may include heavy metals, organic matter, chemicals and the like.

[0046] In this embodiment, the main monitoring module includes a plurality of groups of first data acquisition components 21 distributed along the depth direction, and the auxiliary monitoring module includes a plurality of groups of second data acquisition components 22 distributed along the depth direction; the first data acquisition components 21 and the second data acquisition components 22 are one-to-one corresponding and are respectively arranged at the corresponding monitoring points; each group of first data acquisition components 21 includes a strain sensor 211, a pore pressure sensor 212, a resistivity probe 213 and a TDR sensor 214, which are respectively used to collect the strain, pore pressure, resistivity and water content of the corresponding monitoring point; each group of second data acquisition components 22 includes a TDS sensor 221, which is used to collect the TDS value of the corresponding monitoring point; the auxiliary monitoring module further includes a water level monitoring float 23, which is used to collect the water level of the outflow side of the isolation wall 3.

[0047] In this embodiment, at each monitoring point of the first vertical pipe 11, the strain sensor 211, the pore pressure sensor 212, the resistivity probe 213 and the TDR sensor 214 are circumferentially distributed in the same horizontal plane and are fixedly connected with the outer edge of the first vertical pipe 11.

[0048] The second vertical pipe 12 includes an outer pipe and an inner pipe coaxially arranged and forming a sandwich, and the water level monitoring float 23 is arranged in the sandwich, the outer pipe has a plurality of through holes uniformly arranged on the pipe wall and communicating with the sandwich, and the outer pipe is wrapped with geotextile, which can prevent large particles from entering the through holes while allowing water to enter, thereby ensuring that the underground water 8 can enter the sandwich to provide the water level monitoring float 23 with real-time monitoring of the water level of the outflow side of the isolation wall 3. At each monitoring point of the second vertical pipe 12, the TDS sensor 221 is fixedly connected with the geotextile on the outer side of the second vertical pipe 12.

[0049] The data processing module is used to: a, send the strain and pore pressure of each monitoring point inside the isolation wall 3 during construction to an interactive terminal for feedback to adjust the on-site environmental conditions during construction, such as adjusting the environmental conditions such as temperature, humidity, wind speed and the like to meet the construction requirements.

[0050] The data processing module is further configured to:b. calculate a resistivity change ratio according to the real-time resistivity of each monitoring point, and generate a first early warning signal when the resistivity change ratio of any monitoring point exceeds a preset first change ratio threshold.

[0051] N1 = | p0-p i | / p0

[0052] In the formula, N1 is the resistivity change ratio of a monitoring point; p0 is a resistivity reference value collected by the resistivity probe 213 at the monitoring point within a preset time period after the completion of the construction of the isolation wall 3; p i is the real-time resistivity collected by the resistivity probe 213 at the monitoring point.

[0053] The data processing module is further configured to:c. correct the wall permeability coefficient according to the real-time water content of each monitoring point, and calculate a permeability coefficient change ratio, and generate a second early warning signal when the permeability coefficient change ratio of any monitoring point exceeds a preset second change ratio threshold. In the formula, k is the permeability coefficient; FSI is the free swelling coefficient; e is the porosity; w is the real-time water content of a monitoring point; A and B are constants fitted according to the properties of different bentonite materials, and the values of different materials are different.

[0054]

[0055] In the formula, k is the permeability coefficient; FSI is the free swelling coefficient; e is the porosity; w is the real-time water content of a monitoring point; A and B are constants fitted according to the properties of different bentonite materials, and the values of different materials are different.

[0056] The calculation formula of the permeability coefficient change ratio is:

[0057] M1 = | k0-k i | / k0

[0058] In the formula, M1 is the permeability coefficient change ratio of a monitoring point; w0 is the water content reference value collected by the TDR sensor 214 at the monitoring point within a preset time period after the completion of the construction of the isolation wall 3; k0 is the wall permeability coefficient corrected by w0; k i is the wall permeability coefficient corrected by the real-time water content of the monitoring point.

[0059] In the present application, the significance of the first and second early warning signals is that when the resistivity change exceeds the threshold value or the permeability coefficient predicted by the water content changes by an order of magnitude, it can be used as the main basis for judging whether the isolation wall 3 is broken.

[0060] The data processing module is further configured to:d. judge whether the water level on the outflow side of the isolation wall 3 exceeds a preset water level threshold, and if so, generate a third early warning signal.

[0061] The data processing module is further configured to: e. when the change range of the water level per unit time exceeds the fluctuation range of the background value of the underground water level of the site, calculate a TDS value change ratio according to the real-time TDS value of each monitoring point, and when the TDS value change ratio of any monitoring point exceeds a preset third change ratio threshold, generate a fourth early warning signal. The calculation formula for calculating the TDS value change ratio according to the real-time TDS value of each monitoring point is:

[0062] P1 = |C0-C i | / C0

[0063] In the formula, P1 is the TDS value change ratio of a monitoring point, C0 is the TDS value reference value collected by the TDS sensor 221 at the monitoring point within a preset time period after the completion of the construction of the isolation wall 3, and C i is the real-time TDS value collected by the TDS sensor 221 at the monitoring point.

[0064] It should be noted that the backfill material of the isolation wall 3 will ensure its fluidity when designing the water content. The change of the water level of the underground water 8 over a long period of time may cause the isolation wall 3 to experience dry-wet cycles, but the heavy metal erosion is a convection and diffusion process rather than in dry conditions. At this time, it is not necessary to consider the possibility of breaking through the isolation wall, and it is not necessary to consider the monitoring and early warning of the change of the pollutant concentration. When the water level increases significantly over time, the TDS sensor is turned on to start monitoring the TDS value of the monitoring point, and if the TDS value changes by a multiple (which can be customized), it can be judged that the isolation wall is broken through.

[0065] The above-mentioned a-e operations of the data processing module can be operated at regular intervals, for example, once every 1 hour, and the operation interval can be reasonably set according to the demand for early warning and timeliness. The data processing module generates one or more of the above-mentioned first, second, third and fourth early warning signals, and sends the early warning signal to the interactive terminal, reminding the operation and maintenance personnel of the isolation wall 3, so as to serve as an auxiliary means to judge whether the isolation wall 3 has the risk of being broken through, and to take timely repair measures.

[0066] Embodiment 2

[0067] Please refer to Figure 6 , the embodiment provides a soil-bentonite isolation wall monitoring and early warning system, which is different from the monitoring and early warning system in embodiment 1 in that the construction direction of the isolation wall 3 is not a straight line, that is, a right angle is formed by two straight lines. Of course, in other embodiments, other turning angles can also be set, and the number of turns can also be increased. In this embodiment, a support frame 1 is arranged at the turning position, and the support frames 1 and the vertical distribution points on the other straight lines still refer to the setting principles of the straight line construction direction.

[0068] Specifically, the construction thickness of the isolation wall 3 in the embodiment is 0.6 m, the total length is 50 m, and the isolation wall 3 is divided into a 25-m transverse straight construction part and a 25-m longitudinal straight construction part, and the turning point is at the middle. The monitoring point design still follows the principle that the shallow layer is closely spaced and the deep layer is loosely spaced, and ensures that the interface depth of the water permeable layer 5 and the aquiclude 6 has a point. The horizontal spacing of adjacent support frames 1 does not need to be completely the same, but the spacing should be close to ensure the accuracy of the point data measurement.

[0069] Embodiment 3

[0070] The embodiment provides a construction and monitoring method of the soil-bentonite isolation wall in the embodiment 1 or the embodiment 2, and the method comprises the following steps.

[0071] S1, building a guide wall 4: according to the construction design drawing, marking the construction position of the isolation wall 3, determining the excavation area of the guide wall 4 on both sides, pouring concrete after excavation, forming the guide wall 4, and setting the curing time. The design thickness of the guide wall 4 is 0.3 m, the excavation depth is 0.5 m, and the top of the guide wall 4 is 0.2 m above the ground; the curing time is 7-14 days; in step S2, the specified depth of the aquiclude 6 is 2 m.

[0072] S2, excavating a trench: excavating downward at the site of the proposed isolation wall 3, first penetrating the water permeable layer 5 of the soil, then excavating to the specified depth of the aquiclude 6 at the bottom of the water permeable layer 5 to form a trench, and removing the soil residue at the bottom of the trench.

[0073] S3, building a monitoring and early warning system; wherein the monitoring device 2 is installed on the support frame 1 according to the point design, the breakthrough direction of the pollutant is judged according to the flow direction of the underground water 8, so that the main monitoring module on the support frame 1 is arranged inside the proposed isolation wall 3, and the auxiliary monitoring module on the support frame 1 is arranged on the side of the proposed isolation wall 3 away from the pollution source.

[0074] S4, backfilling the wall material: using the wall material obtained by uniformly mixing silty clay and composite modified bentonite slurry to protect the wall of the trench, and then filling the excavated trench to form the isolation wall 3.

[0075] S5, capping: laying in-situ foundation soil on the top of the isolation wall 3 and the guide wall 4 to form the overburden layer 7 and compacting.

[0076] S6, using the data processing module to receive the monitoring data collected by the monitoring device 2, and regularly performing early warning analysis on the isolation wall 3.

[0077] The above merely describes preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art, according to the technical solution and inventive concept of the present application, makes equivalent replacement or change within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A monitoring and early warning system for earth-bentonite diaphragm walls, characterized by, The application relates to a monitoring device for a diaphragm wall, which comprises the following parts: a support frame (1) comprising a first vertical pipe (11) and a second vertical pipe (12); the first vertical pipe (11) is arranged at the central axis position inside the diaphragm wall (3), and the second vertical pipe (12) is arranged at the side of the diaphragm wall (3) facing away from the pollution source, that is, the outflow side; the first vertical pipe (11) and the second vertical pipe (12) are both provided with a plurality of monitoring points along the depth direction, and the monitoring points on the two vertical pipes are one-to-one corresponding and have the same depth; a monitoring device (2) comprising a main monitoring module arranged on the first vertical pipe (11) and an auxiliary monitoring module arranged on the second vertical pipe (12); the main monitoring module is used for collecting the strain and pore pressure of each monitoring point inside the diaphragm wall (3) in real time during construction of the diaphragm wall (3), and is also used for collecting the resistivity and moisture content of each monitoring point inside the diaphragm wall (3) in real time after the construction of the diaphragm wall (3) is completed; the auxiliary monitoring module is used for collecting the water level of the outflow side of the diaphragm wall (3) and the TDS value of each monitoring point in real time after the construction of the diaphragm wall (3) is completed; a data processing module, which is used for: a, sending the strain and pore pressure of each monitoring point inside the diaphragm wall (3) during construction of the diaphragm wall (3) to an interactive terminal to feedback and adjust the field environment condition during construction; b, calculating the resistivity change ratio according to the real-time resistivity of each monitoring point, and generating a first early warning signal when the resistivity change ratio of any monitoring point exceeds a preset first change ratio threshold; c, correcting the wall permeability coefficient according to the real-time moisture content of each monitoring point, and calculating the permeability coefficient change ratio, and generating a second early warning signal when the permeability coefficient change ratio of any monitoring point exceeds a preset second change ratio threshold; d, judging whether the water level of the outflow side of the diaphragm wall (3) exceeds a preset water level threshold, and generating a third early warning signal if yes; e, calculating the TDS value change ratio according to the real-time TDS value of each monitoring point when the change amplitude of the water level per unit time exceeds the fluctuation range of the underground water level background value of the site, and generating a fourth early warning signal when the TDS value change ratio of any monitoring point exceeds a preset third change ratio threshold.

2. The monitoring and early warning system for earth-bentonite diaphragm walls according to claim 1, characterized in that, The main monitoring module comprises a plurality of groups of first data acquisition components (21) distributed along the depth direction, and the auxiliary monitoring module comprises a plurality of groups of second data acquisition components (22) distributed along the depth direction; the number of the first data acquisition components (21) and the second data acquisition components (22) is one-to-one corresponding and is respectively arranged at the corresponding monitoring points; each group of first data acquisition components (21) comprises a strain sensor (211), a pore pressure sensor (212), a resistivity probe (213) and a TDR sensor (214), which are respectively used for collecting the strain, pore pressure, resistivity and moisture content of the corresponding monitoring point; each group of second data acquisition components (22) comprises a TDS sensor (221) used for collecting the TDS value of the corresponding monitoring point; the auxiliary monitoring module further comprises a water level monitoring float (23) used for collecting the water level of the outflow side of the diaphragm wall (3).

3. The monitoring and early warning system for earth-bentonite diaphragm walls according to claim 2, characterized in that, The calculation formula of the resistivity change ratio according to the real-time resistivity of each monitoring point is: N1 = | p0 - p i | / p0 In the formula, N1 is a resistivity variation ratio of a monitoring point; p0 is a resistivity reference value collected by the resistivity probe (213) at the monitoring point within a preset period after the completion of the construction of the isolation wall (3); p is a real-time resistivity collected by the resistivity probe (213) at the monitoring point. i In the formula, N1 is a resistivity variation ratio of a monitoring point; p0 is a resistivity reference value collected by the resistivity probe (213) at the monitoring point within a preset period after the completion of the construction of the isolation wall (3); p is a real-time resistivity collected by the resistivity probe (213) at the monitoring point.

4. The monitoring and early warning system for earth-bentonite wall according to claim 2, characterized in that, The calculation formula of the wall permeability coefficient is corrected according to the real-time water content of each monitoring point, and is as follows: In the formula, k is the permeability coefficient; FSI is the free swelling coefficient; e is the porosity; ω is the real-time water content of a monitoring point; A and B are constants fitted according to the bentonite material; The calculation formula of the permeability coefficient change ratio is as follows: M1 = |k0 - k i | / k0 In the formula, M1 is a monitoring point permeability coefficient variation ratio; the TDR sensor (214) collects a moisture content reference value ω0 at the monitoring point within a preset period after the construction of the isolation wall (3) is completed; k0 is the wall permeability coefficient corrected by ω0; k i is the wall permeability coefficient corrected by the real-time moisture content at the monitoring point.

5. The monitoring and early warning system for earth-bentonite wall according to claim 2, characterized in that, The calculation formula of the TDS value change ratio is calculated according to the real-time TDS value of each monitoring point, and is as follows: P1 = |C0 - C i | / C0 In the formula, P1 is a TDS value change ratio of a monitoring point; C0 is a TDS value reference value collected by the TDS sensor (221) at the monitoring point within a preset period after the completion of the construction of the isolation wall (3); C i is a real-time TDS value collected by the TDS sensor (221) at the monitoring point.

6. The monitoring and early warning system for earth-clay diaphragm walls according to claim 2, characterized in that, At each monitoring point of the first vertical pipe (11), the strain sensor (211), the pore pressure sensor (212), the resistivity probe (213) and the TDR sensor (214) are circumferentially distributed in the same horizontal plane and fixedly connected with the outer edge circumference of the first vertical pipe (11); the second vertical pipe (12) comprises an outer pipe and an inner pipe coaxially arranged and forming a sandwich layer, and the water level monitoring float (23) is arranged in the sandwich layer; the pipe wall of the outer pipe is uniformly provided with a plurality of through holes in communication with the sandwich layer, and the outer side of the outer pipe is wrapped with geotextile; at each monitoring point of the second vertical pipe (12), the TDS sensor (221) is fixedly connected with the geotextile on the outer side of the second vertical pipe (12).

7. The monitoring and early warning system for earth-bentonite diaphragm walls according to any of claims 2 to 6, characterized in that, The support frame (1) further comprises a horizontal pipe (13); the horizontal pipe (13) is horizontally arranged at the top of the guide wall (4) on both sides of the isolation wall (3), and the top of the first vertical pipe (11) and the second vertical pipe (12) are fixedly connected with the horizontal pipe (13) and form a "T" shaped structure with the plane perpendicular to the construction direction of the isolation wall (3).

8. The monitoring and early warning system for earth-bentonite wall according to claim 7, characterized in that, The bottom of the first vertical pipe (11) and the second vertical pipe (12) is an anchor end, and the depth of the anchor end is greater than the bottom depth of the isolation wall (3).

9. The monitoring and early warning system for earth-bentonite diaphragm walls according to claim 8, characterized in that, A plurality of support frames (1) are arranged, and the plurality of support frames (1) are sequentially distributed along the construction direction of the isolation wall (3); the number of monitoring devices (2) is the same as and corresponds to the number of support frames (1).

10. The monitoring and early warning system for earth-bentonite diaphragm walls according to claim 9, characterized in that, The number of monitoring points in each group of monitoring devices (2) is not less than five, the distance between adjacent monitoring points increases with the increase of the depth, and a monitoring point is arranged at the interface between the permeable layer (5) and the impermeable layer (6) in the soil; when the construction direction of the isolation wall (3) is a straight line, the number of support frames (1) is not less than three, and the horizontal distance between adjacent support frames (1) is not greater than 15m; when the construction direction of the isolation wall (3) is not a straight line, a support frame (1) is arranged at the turning point, and the support frames (1) at other straight lines still refer to the setting principle of the straight line construction direction.

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