An in-situ test method for calculating the catchment area of ​​a tunnel

Abstract

The present invention provides an in-situ test method for solving the drainage area of ​​an adit. The entire adit and the overlying rock mass are taken as the research objects. While regularly monitoring the water output of the adit, rainfall data in the study area is continuously collected. The method aims to establish a mathematical relationship between rainfall and adit seepage on a macro scale, which can more accurately analyze the permeability characteristics of granite.

Description

Technical Field

[0001] The invention relates to the technical field of hydrological exploration, and in particular to an in-situ test method for calculating the catchment area of ​​an adit. Background Art

[0002] The permeability characteristics of rock and soil are an important indicator parameter in geotechnical investigation. In the rock mass, there is a weak layer structure sandwiched between relatively hard rocks at the upper and lower parts. Its mechanical properties are poor, the structure is broken, and it is easy to become muddy when it comes into contact with water, which poses a serious threat to engineering construction. Studying its permeability characteristics is of great significance to the design and calculation of engineering anti-seepage. Indoor permeability tests for poor geological bodies are to remove samples with poor geological bodies from the rock mass and transport them back to the indoor test. The sampling and transportation process causes significant disturbance to the sample structure and cannot accurately reflect the permeability characteristics of the rock and soil. In contrast, in-situ permeability tests are tests conducted in the actual environment of the rock mass, which can maintain the original state to the greatest extent and more realistically reflect the permeability characteristics of the poor geological body.

[0003] An adit is a horizontal tunnel with a direct entrance to the surface, also known as a flat tunnel or flat tunnel. It is used for transporting ore, waste rock, materials, equipment, as well as for ventilation and pedestrian access. An adit has an arched cross-section, typically a triangular arch or circular arch. The adit's catchment area influences the flow within the adit, but currently, no technology exists to calculate this area.

[0004] The information disclosed in the background technology section of this application is only intended to deepen the understanding of the general background technology of this application, and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art. Summary of the Invention

[0005] Based on this, it is necessary to provide an in-situ test method for solving the water catchment area of ​​the adit, in order to address the current problem of no solution to the water catchment area of ​​the adit.

[0006] The above purpose is achieved through the following technical solutions:

[0007] An in-situ test method for calculating the catchment area of ​​an adit, comprising:

[0008] A water channel is set up in the adit, and a water collection well is set up at the adit entrance. The water flow in the adit is introduced into the water collection well through the channel, and the water flow rate is measured;

[0009] Obtain the rainfall characteristics of the area where the adit is located;

[0010] According to the statistics of the adit joints and the actual water seepage situation, the adit is divided into multiple sections, and the water flow rate at the connection between two adjacent sections is counted;

[0011] Analyze rainfall characteristics and water flow in each section to determine the development status of leakage channels in each section of the adit;

[0012] A mathematical model was constructed based on the water balance method and input into the MATLAB CURVE FITTING tool to obtain the catchment area parameters.

[0013] In one embodiment, a water channel is provided in the adit, a water collection well is provided at the adit entrance, water flow in the adit is introduced into the water collection well through the water channel, and the water flow rate is measured, including:

[0014] A 50cm×50cm×50cm square water collection well is dug at the entrance of the adit, and a ruler is placed on the inner wall of the water collection well; the water discharged from the adit is discharged into the water collection well through the dug canal, and a branch channel is set in front of the water collection well for drainage.

[0015] In one embodiment, a water channel is provided in the adit, a water collection well is provided at the adit entrance, water flow in the adit is introduced into the water collection well through the water channel, and the water flow rate is measured, including:

[0016] Clean up debris in the water collection well;

[0017] Open the ditch on the side that flows to the water collection well, and seal the ditch on the side that discharges water;

[0018] Wait for the water to become clear and stable;

[0019] When the water flow is stable and clear, start timing and record the water level at this time;

[0020] After the measurement is completed, the canal will be diverted to open the drainage channel side and the canal flowing to the collection well side will be closed.

[0021] In one embodiment, after the water flow is stable and clear, starting to time and recording the water level at that time includes:

[0022] The current water level is recorded after each preset time interval.

[0023] In one embodiment, after the water flow is stable and clear, starting to time and recording the water level at that time includes:

[0024] After each preset scale interval, record the time required for the preset scale to change.

[0025] In one embodiment, obtaining the rainfall characteristics of the area where the adit is located includes:

[0026] Place rain gauges at target locations and obtain rainfall characteristics.

[0027] In one embodiment, obtaining the rainfall characteristics of the area where the adit is located includes:

[0028] Obtain rainfall characteristics through the meteorological monitoring agency at the target location.

[0029] In one embodiment, based on the statistics of the adit joints and the actual water seepage situation, the adit is divided into multiple sections, and the water flow rate at the connection between two adjacent sections is counted, including:

[0030] Cement water retaining dams are piled up at the connection between two adjacent sections, and two water meters are installed at each water retaining dam to record the water flow.

[0031] In one embodiment, analyzing rainfall characteristics and water flow in each section to determine the development status of leakage channels in each section of the adit includes:

[0032] The time node with the highest daily precipitation was selected to observe the changes in drainage in each section of the adit.

[0033] In one embodiment, analyzing rainfall characteristics and water flow in each section to determine the development status of leakage channels in each section of the adit includes:

[0034] According to the rate of change of water seepage after rain, the development status of leakage channels in each section of the adit is determined.

[0035] The beneficial effects of the present invention are:

[0036] The present invention provides an in-situ test method for solving the drainage area of ​​an adit. The entire adit and the overlying rock mass are taken as the research objects. While regularly monitoring the water output of the adit, rainfall data in the study area is continuously collected. The method aims to establish a mathematical relationship between rainfall and adit seepage on a macro scale, which can more accurately analyze the permeability characteristics of granite. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the adit water seepage test in the present invention;

[0038] Figure 2 This is a scene diagram for recording the amount of seepage water in the present invention;

[0039] Figure 3 This is a statistical chart of concentrated rainfall in the study area from June to August 2020;

[0040] Figure 4 This is a curve diagram of water seepage in the adit in the present invention;

[0041] Figure 5 This is a trend diagram of the water seepage and rainfall in the adit in the present invention;

[0042] Figure 6 The figure is a scatter plot of the normalized seepage volume and rainfall of the adit in the present invention;

[0043] Figure 7 This is a flow rate change trend diagram of the adit segment in the present invention;

[0044] Figure 8 This is the flow distribution diagram of each section of the adit from June 29 to July 1 in the present invention;

[0045] Figure 9 This is a trend chart of flow and rainfall changes in section A of the adit from July 12 to August 3 in the present invention;

[0046] Figure 10 This is a trend chart of flow and rainfall changes in the adit A+B section from July 12 to August 3 in the present invention;

[0047] Figure 11 This is a trend diagram of flow and rainfall changes in the A+B+C section of the adit from July 12 to August 3 in the present invention;

[0048] Figure 12 This is a schematic diagram of the water balance calculation for the adit section in the present invention;

[0049] Figure 13 This is the water seepage table of each section of the adit from June 29 to July 1 in the present invention;

[0050] Figure 14 is the water balance equation for each section of the adit in the present invention;

[0051] Figure 15 This is the water balance model for each section of the adit in the present invention;

[0052] Figure 16 This is a table of water balance calculation results for each section of the adit in the present invention. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0054] The serial numbers of the components herein, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in this application, unless otherwise specified, include direct and indirect connections (couplings). In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc. are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0055] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0056] The embodiment of the present invention provides an in-situ test method for solving the drainage area of ​​the adit, taking the entire adit and the overlying rock mass as the research object ( Figure 1 ), the adit was divided into three sections based on its structural characteristics, connected by a water meter. While regularly monitoring the adit's water output, rainfall data for the study area was continuously collected. The goal was to establish a macroscopic mathematical relationship between rainfall and adit seepage to analyze the permeability characteristics of granite. Specifically, the process included the following steps:

[0057] 1. Design of adit water seepage monitoring scheme

[0058] Based on preliminary statistical results, a 50cm×50cm×50cm square water collection well was dug at the entrance of the adit, and a ruler was placed on the inner wall of the water collection well. The water discharged from the adit was discharged into the water collection well through the dug canal. The canal was set up in front of the water collection well for drainage. The measurement steps are as follows:

[0059] (1) Clean up mud, stones and other debris in the water collection well.

[0060] (2) Open the ditch on the side that flows to the water collection well and seal the ditch on the side that discharges water.

[0061] (3) Wait for the water to become clear and stable. On the one hand, due to the diversion of the ditch, the initial water flow may be mixed with sediment; on the other hand, the diversion will make the water flow unstable.

[0062] (4) When the water flow is stable and clear, start timing and record the water level at that time. After that, record the water level once a minute within ten minutes; record the water level once every two minutes from ten to thirty minutes; record the water level once every five minutes from thirty minutes to one hour; and record the water level once every ten minutes for more than one hour. When the water flow is too fast, you can start timing from a specific scale and set a fixed scale interval according to the specific situation, such as 5cm, 10cm, etc. to record the time ( Figure 2 ).

[0063] (5) After the measurement is completed, divert the water channel to the open drainage channel and close the channel flowing to the water collection well. Use a tool such as a scoop to drain the water and debris from the water collection well. Note that it is not necessary to drain all the water; just ensure that there is enough space for the next test.

[0064] 2. Analysis of the relationship between rainfall and adit water seepage

[0065] (1) Rainfall characteristics

[0066] In this experiment, rain gauges were placed on the roofs of houses next to the reservoir. In addition, data from nearby monitoring stations were collected. According to the precipitation data from the Qinglong River Wuyue Station, there were 16 rainy days in June 2020, with a cumulative rainfall of 422.7 mm and a maximum daily rainfall of 120.1 mm; there were 22 rainy days in July, with a cumulative rainfall of 499.2 mm and a maximum daily rainfall of 144.0 mm; there were 6 rainy days in August, with a cumulative rainfall of 55.5 mm and a maximum daily rainfall of 20.4 mm. Since June, there have been 7 concentrated precipitation processes in the study area, namely June 11-15, 27-30, July 1-5, 10-18, 19-21, 24-26, and August 7-8 ( Figure 3 ), among which, the precipitation exceeded 100 mm on June 27 and July 8.

[0067] (2) Monitoring of water seepage in adit

[0068] Taking into account the statistical results of the adit's joints and the actual seepage conditions, the adit was divided into three sections for flow observation: Section C from 0 to 25.7 m, Section B from 25.7 to 63.8 m, and Section A from 63.8 to 80.0 m. Cement retaining weirs were built at 4 m, 25.7 m, and 63.8 m in depth, and two water meters were installed at each weir to record the water flow.

[0069] 1) Analysis of the trend of water seepage in the adit

[0070] Since mid-June 2020, a 50cm×50cm×50cm water collection well was dug at the entrance of the adit to conduct on-site monitoring of the water seepage in the adit for about two months. The monitoring results are shown in the figure below. Figure 4 .

[0071] According to the rainfall data provided by the Qinglong River Wuyue Station, the changing trends of rainfall and adit water seepage were compared ( Figure 5 ), the amount of water seepage in the adit and rainfall showed a certain correlation and obvious hysteresis ( Figure 6 ).

[0072] During the observation period, rainfall was primarily concentrated in June and July, with a significant decrease beginning in August. Adit seepage showed a fluctuating downward trend, stabilizing after August. During the seven periods of concentrated rainfall, rainfall peaked on June 22, June 27, July 2, July 18, July 21, and August 8, with corresponding flow rates reaching peaks on June 22, June 29, July 3, July 22, July 25, July 28, and August 9. This indicates that adit seepage generally peaks between 0 and 48 hours after the concentrated rainfall, exhibiting a significant lag.

[0073] 2) Analysis of water seepage trend in each section of the adit

[0074] The water seepage of each section of the adit is as follows Figure 7 shown.

[0075] During the concentrated rainfall period from June 27 to June 30, the maximum daily rainfall reached 107.0 mm, and the highest value of the adit water seepage occurred during this period. This rainfall concentrated period was selected to observe the changes in drainage volume in each section of the adit ( Figure 13 、 Figure 8 ).

[0076] Depend on Figure 8 Analysis shows that:

[0077] ① The amount of water seepage in section A gradually decreases over time, but its proportion in the total water seepage increases steadily;

[0078] ② The amount of seepage in Section B shows a slow growth trend over a short period of time, and its proportion in the total drainage volume gradually increases;

[0079] ③The seepage volume of section C shows a clear decreasing trend over time, and its proportion in the total drainage volume also decreases rapidly.

[0080] Combined with the joint and fissure data, seepage in Section A gradually decreases after rain, with a small decrease, indicating moderate joint and fissure development. Similarly, Section C experiences a rapid decrease in seepage after rain, indicating a significant and rapid impact of rainfall. This suggests that leakage pathways are more developed within this section. Section B is unique, with seepage increasing slowly over time within a certain period after rain. Joints and fissures are more developed, suggesting a more complex distribution of leakage pathways within this area.

[0081] The water seepage volume of each section in the adit from mid-July to early August was recorded by setting up water meters at the intersection of each section. Figures 9 to 11 .

[0082] Based on actual observations, there is a certain correlation between the seepage volume in Section A and changes in rainfall. During the observation period, the seepage volume in this area remained above 0, indicating that Section A was constantly flooded. After each concentrated rainfall, the accumulated water was not drained in time before the next rainfall arrived. It wasn't until late July and early August, when there was little or no rainfall for several consecutive days, that Section A finally drained all of the accumulated water. This phenomenon also confirms that Section A of the adit has few joints and fissures, and the leakage channels are generally well developed. On July 31st, during on-site recording, a water meter was found to be partially clogged, and dredging work was carried out, which is why it can be seen that the seepage volume peaked on August 1st.

[0083] Section B: From July 18th to July 28th, the discharge volume in this section closely tracked the precipitation, with the peak discharge occurring after the peak rainfall. Rainfall was low on July 26th, and the previous rainfall in this section had not yet fully drained. This indicates that the seepage volume in Section B continued to decrease around the 27th, but the rate of decrease was decreasing. Unlike Section A, the seepage volumes in Sections A and B matched that of Section A on July 28th, with a flow rate of approximately 0.1 L / s, indicating that Section B had reached a balance between recharge and discharge at that time. After the water meter was cleared on July 31st, Section B reached its peak discharge volume on August 2nd and then rapidly declined. This is because, after the clearing of meter A, rainwater accumulated in Section A flowed through Section B, partially draining through infiltration and partially flowing into Section C, reaching its peak discharge volume. Subsequently, the rainwater accumulated in Section A gradually drained away, and the water flowing into Section B was discharged solely through infiltration.

[0084] Section C: When the weir and water meter were first installed, there was no water in the cave, the water flow was not obvious, and the joints and fissures in Section C were developed, so the drainage was mainly from seepage. Therefore, the data recorded by water meters 5 and 6 for Section C were larger than those for the water meter 6. Figure 15 、 Figure 16The recorded discharge into Section C is smaller. Subsequent rainfall, due to the weirs, gradually accumulated water in each section. The discharge from Section C consisted of both infiltration and drainage through pipes. The discharge flow trend was similar to that of Section B, showing a certain correlation with rainfall trends. From July 28th to 31st, the discharge into Section C was consistently lower than the discharge into Section C, indicating that the infiltration into Section C during this period exceeded the recharge flow by approximately 0.4 L / s. Compared to Section B, infiltration in Section C dominated for a longer period and with higher values, indicating more intense infiltration in Section C and more developed leakage pathways.

[0085] Observation and analysis of the adit flow rate show that permeability is strong at the entrance, relatively strong in the middle but exhibits some hysteresis, and average at the end of the adit. This suggests that the adit leakage channels primarily develop in sections B and C, with stronger development towards the outer edges.

[0086] 3. Function Model Construction

[0087] (1) Mathematical model

[0088] The establishment of this model is based on the water balance method. Studies have shown that the water balance method has good results in small-scale hydrological units with simple groundwater formation conditions. According to the water balance principle, for this monitoring, the difference between the input and output of each section of the adit from July 18 to July 28 is equal to the water storage capacity of the test section. The total water inflow of the test section is mainly rainfall infiltration, and the total consumption includes drainage, infiltration, etc. The humidity in the adit is high, the temperature is low, and there is no sunlight, so evaporation can be ignored. The simplified water balance calculation diagram is as follows Figure 12 shown.

[0089] In the figure, R1, R2, and R3 represent the rainfall infiltration of sections A, B, and C of the adit respectively; I1, I2, and I3 represent the water infiltration of sections A, B, and C of the adit respectively; Q1, Q2, and Q3 represent the water flow rate discharged from sections A, B, and C to the next section (or discharged), respectively. The water balance equations for each section of the adit are as follows: Figure 14 .

[0090] In the formula, the rainfall infiltration R is represented by the rainfall, rainfall infiltration coefficient, and catchment area, and the drainage Q is obtained through water meter monitoring data. The three-parameter model of each section of the adit is established for fitting as follows: Figure 15 .

[0091] (2) Data Analysis

[0092] Input the model into MATLAB CURVE FITTINGTOOL to obtain relevant parameters. MATLAB CURVE FITTINGTOOL is a curve fitting tool based on the least squares method. The fitting results are as follows: Figure 16 .

[0093] The fitting results show that the rainfall infiltration coefficient of section A of the adit is 0.1281, the rainfall infiltration coefficient of section B is 0.1971, and the rainfall infiltration coefficient of section C is 0.2305. The ability to accept rainfall infiltration recharge gradually decreases from the inside to the outside, which is consistent with the preliminary analysis results. Among them, the recharge capacity of sections B and C is relatively close. However, due to the large span of section B, the rock mass in some areas is relatively intact, and local joints and fissures are clayed and chloritized, making its rainfall infiltration coefficient lower than that of section C. The rock mass structure of section A is relatively complete, and its ability to accept rainfall infiltration recharge is the weakest. The catchment areas of sections A, B, and C are relatively consistent, with an average of 0.835×10 -3 km 2 .

[0094] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0095] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that a person of ordinary skill in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of this application. Therefore, the scope of protection of this application shall be determined by the appended claims.

Claims

1. An in-situ test method for calculating the catchment area of ​​an adit, characterized in that: include: A water channel is set up in the adit, and a water collection well is set up at the adit entrance. The water flow in the adit is introduced into the water collection well through the channel, and the water flow rate is measured; Obtain the rainfall characteristics of the area where the adit is located; According to the statistics of the adit joints and the actual water seepage situation, the adit is divided into multiple sections, and the water flow rate at the connection between two adjacent sections is counted; Analyze rainfall characteristics and water flow in each section to determine the development status of leakage channels in each section of the adit; A mathematical model was constructed based on the water balance method and input into the MATLAB CURVE FITTING tool to obtain the catchment area parameters; The water balance equations for sections A, B, and C of the adit are R1-I1=Q1, R2-I2=Q2-Q1, and R3-I3=Q3-Q2 respectively; Among them, R1, R2, and R3 represent the rainfall infiltration of sections A, B, and C of the adit respectively; I1, I2, and I3 represent the infiltration of accumulated water in sections A, B, and C of the adit respectively; Q1, Q2, and Q3 represent the flow rate of water discharged from sections A, B, and C to the next section or discharged respectively; The rainfall infiltration water R1, R2, R3 of the adit sections A, B, C are represented by the rainfall p, the rainfall infiltration coefficients a1, a2, a3 of the adit sections A, B, C, and the catchment areas s1, s2, s3 of the adit sections A, B, C. A three-parameter model of each adit section is established for fitting. The three-parameter models of the adit sections A, B, and C are a1s1p-I1=Q1, a2s2p-I2=Q2-Q1, and a3s3p-I3=Q3-Q2, respectively.

2. The in-situ test method for calculating the catchment area of ​​an adit according to claim 1, characterized in that: A water channel is set up in the adit, and a water collection well is set up at the adit entrance. The water flow in the adit is introduced into the water collection well through the channel, and the water flow rate is measured, including: A square water collection well of 50cm×50cm×50cm is dug at the entrance of the adit, and a ruler is placed on the inner wall of the water collection well; the water discharged from the adit is discharged into the water collection well through the dug canal, and a branch channel is set in front of the water collection well for drainage.

3. The in-situ test method for calculating the catchment area of ​​an adit according to claim 1, characterized in that: A water channel is set up in the adit, and a water collection well is set up at the adit entrance. The water flow in the adit is introduced into the water collection well through the channel, and the water flow rate is measured, including: Clean up debris in the water collection well; Open the ditch on the side that flows to the water collection well, and seal the ditch on the side that discharges water; Wait for the water to become clear and stable; When the water flow is stable and clear, start timing and record the water level at this time; After the measurement is completed, the canal will be diverted to open the drainage channel side and the canal flowing to the collection well side will be closed.

4. The in-situ test method for determining the catchment area of ​​an adit according to claim 3, characterized in that: When the water flow is stable and clear, start timing and record the water level at this time: The current water level is recorded after each preset time interval.

5. The in-situ test method for calculating the catchment area of ​​an adit according to claim 3, characterized in that: When the water flow is stable and clear, start timing and record the water level at this time: After each preset scale interval, record the time required for the preset scale to change.

6. The in-situ test method for calculating the catchment area of ​​an adit according to claim 1, characterized in that: Obtaining rainfall characteristics of the area where the adit is located includes: Place rain gauges at target locations and obtain rainfall characteristics.

7. The in-situ test method for calculating the catchment area of ​​an adit according to claim 1, characterized in that: Obtaining rainfall characteristics of the area where the adit is located includes: Obtain rainfall characteristics through the meteorological monitoring agency at the target location.

8. The in-situ test method for calculating the catchment area of ​​an adit according to claim 1, characterized in that: According to the statistics of the adit joints and the actual water seepage situation, the adit is divided into multiple sections, and the water flow at the connection between two adjacent sections is statistically analyzed, including: Cement water retaining dams are piled up at the connection between two adjacent sections, and two water meters are installed at each water retaining dam to record the water flow.

9. The in-situ test method for calculating the catchment area of ​​an adit according to claim 1, characterized in that: By analyzing the rainfall characteristics and water flow in each section, the development status of leakage channels in each section of the adit was determined, including: The time node with the highest daily precipitation was selected to observe the changes in drainage in each section of the adit.

10. The in-situ test method for calculating the catchment area of ​​an adit according to claim 1, characterized in that: By analyzing the rainfall characteristics and water flow in each section, the development status of leakage channels in each section of the adit was determined, including: According to the rate of change of water seepage after rain, the development status of leakage channels in each section of the adit is determined.

Images