CN109238229B - Temperature compensation method for surface subsidence value based on hydrostatic level monitoring - Google Patents

Abstract

The invention belongs to the technical field of engineering monitoring, and in particular relates to a temperature compensation method based on a surface settlement value monitored by a static level. The steps are as follows: The first step is to determine the geological conditions. The second step is to determine the plan for arranging the static level at the surface settlement measuring points. The third step calculates the cumulative settlement value. Step 4: Arrange a temperature sensor on each static level to monitor the change of ambient temperature with time. The fifth step determines the delay time t. The sixth step is to determine the error value of temperature on surface deformation. The seventh step is to perform temperature compensation on the settlement value. According to the third step, the accumulated settlement value of the N _i measuring point at time t _x is calculated, and the accumulated settlement value is subtracted from the error value to realize the temperature compensation for the accumulated settlement value of the N _i measuring point. The invention can provide a temperature compensation method based on the surface subsidence value monitored by the static level, which greatly improves the monitoring accuracy of the surface subsidence value monitored by the static level.

Description

A Temperature Compensation Method for Surface Subsidence Monitored by Static Level

technical field

The invention belongs to the technical field of engineering monitoring, and in particular relates to a temperature compensation method based on a surface settlement value monitored by a static level.

Background technique

With the rapid development of science and technology and the continuous acceleration of my country's modernization process, all kinds of high-rise buildings, important buildings and structures in cities are increasing day by day. Abnormal vertical displacement of building (structure) itself or old goaf is often a precursor to instability and accident. Therefore, vertical displacement monitoring is particularly important. At present, the main methods of vertical displacement measurement include static level, theodolite, rangefinder and so on. Theodolites generally have a higher unit price and are easily affected by the environment, so they are not suitable for large-scale long-term monitoring, while rangefinders require manual measurement and cannot achieve uninterrupted monitoring. Compared with traditional vertical displacement monitoring equipment, the static level has a unit price. It can be deployed on a large scale, and has many advantages of overcoming harsh environments. It is widely used in the construction industry and underground space engineering industry.

The hydrostatic leveling system is to inject a certain amount of liquid into the container connected by the pipeline, and the liquid in all the containers will flow freely in the pipeline. Measure the relative change of the liquid level in the container at each measuring point, and then calculate the relative settlement of each point relative to the base point.

The accuracy of the static level measurement system will be affected by both external factors and instruments. The measurement error of the hydrostatic level monitoring system is mainly influenced by external factors, such as temperature, air pressure and other factors; the influence of the structure of the instrument itself, such as liquid volatilization, stability of electronic components, equipment installation errors, etc. The main accuracy factors of the static level measurement system are temperature and delay effects. For example, the increase in temperature at a certain point causes the liquid volume to increase and the liquid level to rise, but in fact no settlement deformation occurs at this point. It is obviously wrong to conclude that "settling has occurred at this point"; at the same time, when there is a lot of liquid in the container and when the external temperature changes, it will take a while for the liquid to absorb or release heat. Causes the liquid temperature to be out of sync with the outside temperature. It is precisely because of the existence of this delay effect that the temperature value monitored at a certain time is not the real liquid temperature value. In order to reduce this error, further delay effect correction is required. Therefore, there is an urgent need for a temperature compensation method based on the surface subsidence value monitored by the static level, which can improve the accuracy of the static level monitoring, ensure the safety of the monitored project, and improve the benefits of the enterprise.

SUMMARY OF THE INVENTION

What the present invention aims to solve is the problem that the surface settlement value monitored by the static level is greatly affected by temperature, and the present invention provides a temperature compensation method based on the surface settlement value monitored by the static level, so as to provide the The precision of the subsidence value.

The technical scheme of the present invention is as follows:

A temperature compensation method based on the surface subsidence value monitored by a static level, comprising the following steps:

The first step: determine the scope of the shallow goaf and the engineering geological conditions of the overlying rock strata by means of geophysical prospecting and drilling.

Step 2: According to the scope of the shallow goaf and the engineering geological conditions of the overlying strata, determine the plan for arranging the static level at the surface subsidence measuring points. According to the monitoring accuracy and monitoring range, choose a static level. According to the temperature change range of the monitoring area throughout the year, select the connecting fluid to prevent the connecting fluid from freezing in winter.

Connecting pipes are arranged in two adjacent static levels, one side of the first static level is connected with the liquid storage pipe, and the other side is connected with the adjacent static level, wherein the liquid storage tank is communicated with the atmosphere to form a connector.

Pour the connecting liquid into the reservoir until the connecting liquid fills all the connecting pipes and the static level, then close the end of the last static level.

A four-core cable is used to connect the adjacent static level, and the static level is connected in series to the data acquisition terminal through the four-core cable. Among them, two of the four-core cables are used for power supply, and the other two are used to transmit the data collected by the static level to the data acquisition terminal.

The data acquisition terminal has two functions. First, it transforms the external 220V power supply into the power supply voltage of the static level; second, it transmits the data information of the static level to the cloud platform through the 4G network for viewing and processing.

Further, in the present invention, 12 static level gauges are arranged on the roof of the goaf, and the monitored goaf has a length of 250-260 m and a width of 100-110 m.

In the present invention, the SD-226 type static level instrument is selected, and the monitoring accuracy is 0.2 mm; the 55% ethylene glycol aqueous solution with the freezing point of -45° C. is selected as the communication liquid.

Step 3: After the installation of the static level is completed, record the first liquid level reading of each static level as the initial value. The data acquisition terminal collects data every T minutes, and the previous liquid level reading is subtracted from the liquid level collected this time. The surface reading is the instant settlement value, and the cumulative summation of the instant settlement value is the cumulative settlement value.

At the temperature of T1, point N1 is the arrangement point _of the _first static level, as the reference point, _N2 to Ni are the measuring points, _i =2, 3, . . . , j, . . .

将这些压力值转化为4℃时对应的水面标高，此时水面标高即为静力水准仪监测到各个测点的初始读数，分别为

在初始状态，N_i测点相对于N₁的高度

The pressures monitored by the N ₁ to N _i static level gauges are respectively

These pressure values are converted into the corresponding water surface elevation at 4°C. At this time, the water surface elevation is the initial reading of each measuring point monitored by the static level, respectively:

In the initial state, the height of N _i measuring point relative to N ₁

由于N₁点为第一个静力水准仪的布置点，测点未发生沉降。在此状态下，N_i测点相对于N₁的高度

N_i测点发生的即时沉降值为

_The temperature changes from the temperature of T1 to the temperature of T2. When the settlement of the measuring points from _N2 to _Ni occurs, the readings of each measuring point monitored by the static level are as follows _:

Since point N ₁ is the arrangement point of the first static level, the measuring point does not settle. In this state, the height of N _i measuring point relative to N ₁

The immediate subsidence value of the _Ni measuring point is

在此状态，N_i测点相对于N₁低

N_i测点发生的即时沉降值为

The temperature changes from T ₂ temperature to T ₃ temperature. When the settlement of N ₂ to _Ni measuring points occurs again, the readings of each measuring point monitored by the static level are as follows:

In this state, the N _i measuring point is low relative to N ₁

The immediate subsidence value of the _Ni measuring point is

_The temperature changes from T1 temperature to T3 temperature, and the accumulated sedimentation value _{of Ni} measuring point is

为在T_i温度时储液罐中的液面相对于第j个液压水准仪的高度。where ρ ₀ is the density of the connected liquid at 4°C, ρ _Ti is the density of the connected liquid at temperature _Ti ,

is the height of the liquid level in the liquid storage tank relative to the _jth hydraulic level at the temperature Ti.

Step 4: Select a temperature sensor, arrange a temperature sensor on each static level, monitor the change of ambient temperature with time, set the sampling frequency of the temperature sensor to be collected once every T minutes, and the temperature sensor will monitor the temperature data. Upload to the cloud platform for viewing and processing.

Further, the present invention adopts NTC type thermistor temperature sensor, and arranges 12 temperature sensors on 12 static level gauges.

Step 5: Determine the delay time t. Due to the transmission process of hydraulic pressure, the influence of temperature on the surface subsidence value monitored based on the static level has a delayed effect.

According to the temperature data monitored by the temperature sensor, take the monitoring time interval T as the unit, and list the temperature changing curve with time. Select the _Ni measuring point, and list the variation curve of accumulated sedimentation value with time and the variation curve of temperature with time in one day. Find the sedimentation peak in the curve of cumulative sedimentation value changing with time in one day, and determine the time corresponding to the sedimentation peak. Find the temperature peak in the temperature change curve with time in one day, and determine the time corresponding to the temperature peak. The absolute value of the difference between the time corresponding to the settlement peak and the time corresponding to the temperature peak is the delay time t of the N _i measuring point.

Step 6: Determine the error value of the temperature on the surface deformation according to the influence law of temperature on the density of the connected fluid and the sensor reading in the initial state.

When the temperature changes from T1 temperature to _T3 temperature, the cumulative sedimentation value _{of Ni} measuring point is:

When the temperature _of T1 changes to the temperature _of T3, the surface subsidence does not occur, that is:

_At this time, the accumulated sedimentation value _of the _Ni measuring point is the error caused by the temperature change from T1 temperature to T3 temperature, and the error value is:

为初始状态下，N₁相对于N_i测点的高度。in,

is the height of N ₁ relative to the N _i measuring point in the initial state.

为正表示温度导致测点的累积沉降值向下波动，误差为负表示温度导致测点的累积沉降值向上波动。difference

A positive value means that the temperature causes the accumulated settlement value of the measuring point to fluctuate downward, and a negative error means that the temperature causes the accumulated settlement value of the measuring point to fluctuate upward.

Step 7: Perform temperature compensation on the settlement value.

其中，t_x为任意时刻，

为在T_x温度时储液罐中的液面相对于第i个液压水准仪的高度。The temperature in the initial state is set as T ₁ , and the temperature at T ₁ is used as the reference temperature. At (t _x -t) the temperature is T _x , and the error of the _Ni measuring point due to the temperature is

Among them, t _x is any time,

is the height of the liquid level in the liquid storage tank relative to the _i -th hydraulic level at the Tx temperature.

即实现了对N_i测点的累积沉降值进行温度补偿。According to the third step, the accumulated settlement value of the measuring point _Ni at time t _x is calculated, and the accumulated settlement value is subtracted from the accumulated settlement value.

That is, the temperature compensation of the accumulated settlement value of the _Ni measuring point is realized.

Beneficial effects of the present invention:

The invention can provide a temperature compensation method based on the surface subsidence value monitored by the static level, which greatly improves the monitoring accuracy of the surface subsidence value monitored by the static level.

Description of drawings

Figure 1 is the temperature change state of the surface subsidence monitoring system based on the static level.

Figure 2 compares the variation trend of surface subsidence value with time and the variation trend of temperature with time.

Figure 3 shows the trend of the daily average sedimentation data and temperature data of the measuring points with the date.

Figure 4 shows the temperature compensation method based on the surface subsidence value monitored by the static level.

Figure 5 is the layout of the measuring points of the surface subsidence monitoring system based on the static level.

Fig. 6 is the density change curve of 55% ethylene glycol aqueous solution with temperature.

Detailed ways

The technical solutions of the present invention will be described clearly and completely below with reference to the implementation examples.

The invention discloses a temperature compensation method based on the surface subsidence value monitored by a static level. The method is now fully described through an implementation case of surface subsidence monitoring in a goaf of an open-pit iron ore. The specific steps are as follows:

Step 1: Use the CMS three-dimensional laser scanner to detect the shallow goaf of an open-pit iron mine, determine the location range and general shape of the shallow goaf, and use the BHCTV borehole imaging according to the location range of the shallow goaf. The instrument carries out borehole camera detection on the roof of the open area, and determines the engineering geological conditions of the overlying strata in the shallow open area.

Step 2: According to the scope of the shallow goaf obtained from the detection and the engineering geological conditions of the overlying rock strata, it is determined that 12 static levels are arranged on the roof of the goaf (see Figure 5). The length of the monitored goaf is about 250m, the width is about 100m, and the required monitoring accuracy is 0.2mm. According to the above requirements, the SD-226 static level is selected. The goaf is located in the alpine region of Northeast China, and the minimum temperature in winter can reach -30°C. Therefore, a 55% ethylene glycol aqueous solution with a freezing point of -45°C is selected as the connecting fluid to prevent freezing in winter. Connecting pipelines, one side of the first static level is connected with the liquid storage pipe, and one side is connected with the adjacent static level, wherein the liquid storage tank is the same as the atmosphere, forming a communication device. Pour the connecting liquid into the reservoir until the connecting liquid fills all the connecting pipes and the static level, then close the end of the last static level. A four-core cable is used to connect two adjacent static levels, two are used for power supply, and the other two are used to transmit the data collected by the static level. The acquisition frequency was once every five minutes. The data acquisition terminal has two functions. First, it transforms the external 220V power supply to a suitable voltage to supply power to the static level; second, it transmits the static level to the cloud platform with 4G network for viewing and processing.

Step 3: After the static level is installed, record the first liquid level reading of each static level as the initial value. The data acquisition terminal collects data every five minutes, and the previous liquid level reading is subtracted from the one collected this time. The liquid level reading is the instant settlement value, and the cumulative summation of the instant settlement value is the cumulative settlement value.

Step 4: According to the needs of the site, select the NTC thermistor temperature sensor, arrange the 12 temperature sensors at the 12 static level gauges, monitor the change of the ambient temperature with time, and adjust the sampling frequency of the temperature sensor to every five Collect once a minute, and upload the monitored temperature data to the cloud platform through the temperature monitoring system for viewing and processing.

The fifth step: with reference to the density change curve of 55% ethylene glycol aqueous solution with temperature (Fig. 6), find out the density change of 55% ethylene glycol aqueous solution and the readings of the initial state reference point and each measuring point, using the temperature compensation formula Temperature compensation is performed based on the settlement value monitored by the static level.

Claims (5)

1. a temperature compensation method based on the surface subsidence value monitored by static level, is characterized in that, comprises the following steps: The first step: determine the scope of the shallow goaf and the engineering geological conditions of the overlying strata by means of geophysical prospecting and drilling; Step 2: According to the scope of the shallow goaf and the engineering geological conditions of the overlying strata, determine the plan for arranging the static level at the surface subsidence measuring point; select the static level according to the monitoring accuracy and monitoring range; according to the monitoring area According to the temperature change range of the four seasons of the year, select the connecting liquid to prevent the connecting liquid from freezing in winter; Connecting pipes are arranged in two adjacent static levels, one side of the first static level is connected with the liquid storage pipe, and the other side is connected with the adjacent static level, wherein the liquid storage tank is communicated with the atmosphere to form a connector; Pour the connecting liquid into the liquid storage tank until the connecting liquid fills all the connecting pipes and the static level, and then close the end of the last static level; Four-core cables are used to connect the adjacent static levels, and after the static levels are connected in series, the data acquisition terminals are connected through four-core cables; two of the four-core cables are used for power supply, and the other two are used to transmit the data collected by the static level. The data is transmitted to the data acquisition terminal; Step 3: After the installation of the static level is completed, record the first liquid level reading of each static level as the initial value. The data acquisition terminal collects data every T minutes, and the previous liquid level reading is subtracted from the liquid level collected this time. The surface reading is the instant settlement value, and the cumulative summation of the instant settlement value is the cumulative settlement value; At the temperature of T1, point N1 is the arrangement point _of the _first static level, as the reference point, _N2 to Ni are the measuring points, _i =2,3,...,j,...; The pressures monitored by the N ₁ to N _i static level gauges are respectively

These pressure values are converted into the corresponding water surface elevation at 4°C. At this time, the water surface elevation is the initial reading of each measuring point monitored by the static level, respectively:

In the initial state, the height of N _i measuring point relative to N ₁

_The temperature changes from the temperature of T1 to the temperature of T2. When the settlement of the measuring points from _N2 to _Ni occurs, the readings of each measuring point monitored by the static level are as follows _:

Since point N ₁ is the arrangement point of the first static level, the measuring point does not settle; in this state, the height of measuring point N _i relative to N ₁

The immediate subsidence value of the _Ni measuring point is

The temperature changes from T ₂ temperature to T ₃ temperature. When the settlement of N ₂ to _Ni measuring points occurs again, the readings of each measuring point monitored by the static level are as follows:

In this state, the N _i measuring point is low relative to N ₁

The immediate subsidence value of the _Ni measuring point is

_The temperature changes from T1 temperature to T3 temperature, and the accumulated sedimentation value _{of Ni} measuring point is

where ρ ₀ is the density of the connected liquid at 4°C, ρ _Ti is the density of the connected liquid at temperature _Ti ,

is the height of the liquid level in the liquid storage tank relative to the i-th hydraulic level at the temperature of T _x ; Step 4: Select a temperature sensor, arrange a temperature sensor on each static level, monitor the change of ambient temperature with time, set the sampling frequency of the temperature sensor to be collected once every T minutes, and the temperature sensor will monitor the temperature data. Upload to the cloud platform for viewing and processing; Step 5: Determine the delay time t; According to the temperature data monitored by the temperature sensor, take the monitoring time interval T as the unit, list the change curve of temperature with time; select the N _i measurement point, list the change curve of accumulated sedimentation value with time and the change of temperature with time in one day curve; find the settlement peak value in the curve of the cumulative sedimentation value over time in one day, and determine the time corresponding to the sedimentation peak value; find the temperature peak value in the temperature change curve with time in one day, and determine the time corresponding to the temperature peak value; The absolute value of the difference between the time and the time corresponding to the peak temperature is the delay time t of the N _i measuring point; Step 6: Determine the error value of the temperature on the surface deformation according to the influence law of temperature on the density of the connected liquid and the sensor reading in the initial state; When the temperature changes from T1 temperature to _T3 temperature, the cumulative sedimentation value _{of Ni} measuring point is:

When the temperature _of T1 changes to the temperature _of T3, the surface subsidence does not occur, that is:

_At this time, the accumulated sedimentation value _of the _Ni measuring point is the error caused by the temperature change from T1 temperature to T3 temperature, and the error value is:

in,

is the height of N ₁ relative to the N _i measuring point in the initial state; difference

If it is positive, it means that the temperature causes the accumulated settlement value of the measuring point to fluctuate downward, and if the error is negative, it means that the temperature causes the accumulated settlement value of the measuring point to fluctuate upward; Step 7: Perform temperature compensation on the settlement value; Let the temperature in the initial state be T ₁ , and take the temperature of T ₁ as the reference temperature; at the time of (t _x -t), the temperature is T _x , and the error caused by the temperature of the _Ni measuring point is

Among them, t _x is any time,

is the height of the liquid level in the liquid storage tank relative to the i-th hydraulic level at the temperature of T _x ; According to the third step, the accumulated settlement value of the measuring point _Ni at time t _x is calculated, and the accumulated settlement value is subtracted from the accumulated settlement value.

That is, the temperature compensation of the accumulated settlement value of the _Ni measuring point is realized. 2. The temperature compensation method for surface subsidence value as claimed in claim 1, characterized in that, in the second step, 12 static levels are arranged on the roof of the goaf, and the length of the monitored goaf is 250-260m, The width is 100-110m, and the static level is SD-226 type static level, and the monitoring accuracy is 0.2mm. 3. The temperature compensation method for the surface subsidence value according to claim 1 or 2, characterized in that, in the fourth step, the temperature sensor adopts an NTC type thermistor temperature sensor, and the temperature sensor is arranged on the static level. 4. The temperature compensation method for the surface subsidence value according to claim 1 or 2, wherein in the second step, a 55% ethylene glycol aqueous solution with a freezing point of -45°C is selected as the communication liquid. 5 . The temperature compensation method for the surface subsidence value according to claim 3 , wherein, in the second step, a 55% ethylene glycol aqueous solution with a freezing point of -45° C. is selected as the communication liquid. 6 .

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