CN105674955B - Manual inflation's method controls the field testing procedure and device of surface subsidence - Google Patents

Abstract

The present invention relates to a test method and technical field for controlling land subsidence. It aims to provide a field test method for controlling land subsidence by using compressed air instead of fresh water recharged into an underground aquifer, which can solve the waste of water resources in previous methods of controlling land subsidence. , time-consuming, labor-intensive, high cost and other issues, and will not cause secondary pollution to the underground environment. The technical scheme adopted by the present invention is a field test method and device for controlling ground subsidence by artificial aeration method, including the following parts: (1) an aeration well and a monitoring well (2) an aeration system (3) a control system (4) an acquisition system. The invention is mainly applied to the test occasion of controlling ground subsidence.

Description

Field Test Method and Device for Controlling Land Subsidence by Artificial Inflating Method

technical field

The invention relates to a test method and technical field for controlling ground subsidence, in particular to an on-site test method and device for controlling ground subsidence by an artificial inflation method.

Background technique

Land subsidence is a kind of slow-changing geological disaster caused by the reduction of regional ground elevation due to the compression of the crust and surface soil under the action of natural and human factors, and it is an irreparable permanent loss of environment and resources. my country's land subsidence is mainly concentrated in the central and eastern coastal cities, which is extremely harmful to these areas of rapid economic development. Judging from the characteristics of land subsidence in our country, the over-exploitation of groundwater is the main reason, and it also includes natural factors such as geological deformation. From the basic situation of land subsidence, the area of land subsidence is large and the process is relatively slow, so it is difficult to find the problem of subsidence in the early stage, and it has a great impact on people's life, becoming a serious environmental geological disaster. Therefore, it is of great practical significance to carry out exploration research on controlling land subsidence.

At present, the control of land subsidence mainly consists of strengthening monitoring and prediction, combining comprehensive prevention and control with regional prevention and control, limiting or reducing the amount of groundwater exploitation, adjusting the level of groundwater exploitation, rationally controlling the exploitation time, artificial recharge of groundwater, and increasing publicity and education on land subsidence prevention and control. Start with strength and so on. Reducing the amount of groundwater extraction may exacerbate the contradiction between water supply and demand; artificial recharging requires a large amount of water resources, and for water-scarce areas, water conservancy projects need to be built, which will inevitably increase costs; publicity and education have little contribution to subsidence control; in short, these disasters Treatment measures, monitoring and research measures, and administrative regulations cannot effectively control land subsidence. Therefore, this requires trying new experimental methods to explore and study the problem of land subsidence, so as to achieve the purpose of effectively controlling land subsidence.

Contents of the invention

In order to overcome the deficiencies in the prior art, the present invention aims to provide a field test method for controlling land subsidence by using compressed air instead of fresh water to recharge into the underground aquifer, which can solve the problems of wasting water resources and time-consuming problems in previous methods of controlling land subsidence. Laborious, high cost and other problems, and will not cause secondary pollution to the underground environment.

The technical scheme that the present invention adopts is, the field test device that artificial inflation method controls ground subsidence, comprises the following parts:

(1) Inflatable wells and monitoring wells

Including 1 aeration well, several monitoring wells are set up according to the needs, and the monitoring wells are arranged along the periphery of the aeration well;

(2) Inflatable system

The air filling process is realized by the air compressor. The working pressure of the air compressor depends on the depth of the air well. The greater the depth, the greater the working pressure requirement. , the greater the compressed air flow rate of the air compressor is required;

(3) Control system

It consists of a primary pressure reducing valve, a filter, a high precision pressure reducing valve and a digital pressure gauge, where the filter includes an oil removal filter and/or a dry filter;

(4) Acquisition system

Set up TDR, soil pressure cell, and piezometer in each monitoring well, and also include: use 8-channel soil moisture monitoring and acquisition instrument to collect soil volumetric water content and soil temperature data, and use 16-channel strain acquisition instrument to collect soil pressure values and pore water pressure values, the elevation value is obtained by using a level gauge with leveling observation piles.

The high-pressure air generated by the air compressor is introduced into the ground through the air-supply steel pipe in the inflatable well, and the air-supply steel pipe is made into a screen hole in the air-supply section of the air-supply steel pipe, and the air-supply steel pipe is fixed underground to prevent it from moving during the inflation process.

Depth layout requirements for monitoring wells: the depth of monitoring wells in the south and north directions should be greater than the depth of the upper end of the aerated section; the depth of monitoring wells in the northeast and southwest directions should be located in the middle of the first soil layer adjacent to the upper part of the aerated aquifer ; The depth positions of the monitoring wells in the four directions of due east, due west, southeast and northwest should be in the middle of the second soil layer above the aerated aquifer. The specific depth of the monitoring well is determined according to the soil layer distribution.

Depth layout requirements for monitoring wells: the depth of monitoring wells in the two directions of due south and due north should be greater than the depth of the upper end of the aeration outlet in the aerated well; The depth of monitoring wells in the four directions of due east, due west, southeast and northwest should be in the middle of the second soil layer in the upper part of the aerated aquifer; the specific depth value of the monitoring well is determined according to the distribution of soil layers.

The field test method for controlling land subsidence by artificial inflation method includes the following steps:

1) One aeration well is set up, and several monitoring wells are set up as required, and the monitoring wells are arranged along the periphery of the aeration well;

2) Use an air compressor to realize the inflation process. The working pressure of the air compressor depends on the depth of the aeration well. The greater the depth, the greater the working pressure requirement; The larger the value, the greater the compressed air flow rate of the air compressor is required;

3) Use the primary pressure reducing valve, filter, high-precision pressure reducing valve and digital pressure gauge to guide the gas generated by the air compressor into the aeration well, wherein the filter includes an oil removal filter and/or a dry filter;

Use TDR, soil pressure cell, and piezometer to measure data, use 8-channel soil moisture monitoring and acquisition instrument to collect soil volumetric water content and soil temperature data, and use 16-channel strain acquisition instrument to collect soil pressure and pore water pressure values , use the level gauge with the leveling observation pile to obtain the elevation value.

During the use of the air compressor, the pressure should be increased step by step, and the pressure must not be reversed.

The location layout principle of the aeration section in the aeration well is that it should be located in the soil layer with better permeability, the soil layer with better permeability is silt or silt layer, and there are relatively impermeable layers with lower permeability above and below the gas injection section; The principle of depth arrangement of monitoring wells is to meet the data acquisition near the inflatable section and the upper part of the inflatable section. Similarly, monitoring wells with large radial distances have reduced depths and are located at different depths between the upper part of the aerated section and the groundwater table.

Features and beneficial effects of the present invention are:

Compared with existing technologies such as artificial fresh water recharge, the present invention saves precious fresh water resources and does not cause pollution to the underground environment; the present invention uses more mature sensors and collectors to obtain real-time synchronous data in the experimental area, and is easy to operate It is fast and can be carried out for a long time; the present invention uses air instead of fresh water to recharge into the underground aquifer, which is a cost-saving and efficient exploration and research.

Description of drawings:

Figure 1 is a schematic diagram of the section layout of the gas-filled well and the observation well;

Figure 2 is a schematic diagram of the plane layout of the gas-filled well and the observation well;

Fig. 3 is an electric mobile air compressor;

Fig. 4 is a pressure regulation control panel;

Figure 5 is a partial data curve collected;

Figure 6 is a partial data list collected;

Figure 7 is a schematic diagram of the complete device.

Detailed ways

The present invention is realized through the following technical solutions.

A field test method for controlling ground subsidence by artificial inflation method, comprising the following parts:

(1) Inflatable wells and monitoring wells

The present invention includes one gas-filled well, and several monitoring wells can be installed as required. See attached drawing 1 for a schematic diagram of a section layout, and see attached drawing 2 for a schematic diagram of a plane layout.

(2) Inflatable system

The inflation process is realized by the air compressor, because it is suitable to use a mobile type in the field, as shown in Figure 3, the working pressure of the air compressor depends on the depth of the inflation well, the greater the depth, the greater the working pressure requirement; The compressed air flow rate of the air compressor is selected according to the aperture size of the inflatable well. The larger the aperture, the larger the compressed air flow rate of the air compressor is required.

(3) Control system

It is composed of a primary pressure reducing valve, a filter, a high precision pressure reducing valve and a digital pressure gauge. The compressed air from the air compressor passes through the above devices in sequence. Among them, the primary pressure reducing valve is a valve that reduces the inlet pressure to a certain required outlet pressure through adjustment, and relies on the energy of the medium itself to keep the outlet pressure automatically stable; the filter is to remove a small amount of oil, water, and Dust and other substances. When compressed air is filtered through the first-stage cylindrical mesh, a coalescing effect occurs, larger particles will be adsorbed on the filter material, and moisture will condense into larger water droplets. When entering the separation, the compressed air speed slows down, so that the particles gather again, and the water mist falls on a honeycomb water trap. The water flows along the bottom to the drain, where it is removed through an automatic or manual drain valve. At this time, more than 95% of water droplets, oil droplets and large particles in the compressed air have been filtered out by the first filter element, and the compressed air filtered by the first stage enters the second stage filter element. When the compressed air passes through the second-stage fiber filter made of special materials, thousands of small vortices will be generated, and the compressed air will be accelerated dozens of times to form a vacuum state, which is not filtered out in the first filter The water droplets are vaporized, converted, and filtered out again, and at the same time, particles as small as 5 microns are completely removed by the second filter; the high-precision pressure reducing valve works the same as the primary pressure reducing valve, but the pressure adjustment accuracy is higher ;The digital pressure gauge is based on the Magnus effect, and can display flow, pressure, temperature and other indicators on the instrument panel. The instrument has a built-in differential pressure sensor, which can record pressure and flow in real time by connecting with a computer. data. The schematic diagram of the control panel is shown in Figure 4.

(4) Acquisition system

Including the collection of data measured by TDR, soil pressure cell, piezometer and elevation data, the present invention adopts 8-channel soil moisture monitoring and acquisition instrument to collect soil volume moisture content and soil temperature data, and adopts 16-channel strain acquisition instrument The soil pressure value and pore water pressure value are collected, and the level is used to cooperate with the leveling observation pile to obtain the elevation value. Some schematic diagrams of the collected data are shown in Figures 5 and 6.

The present invention will be further described in detail below in conjunction with specific embodiments. The schematic diagram of the complete device in this example is shown in Figure 7.

(1) Site selection

Field tests should be carried out in areas with known stratum data and good permeability soil layers as much as possible, which saves the cost of early tests. This field test was selected in the Vegetable Research Institute of Tianjin Kerun Agricultural Technology Co., Ltd., No. 3, Haitai Development Road, Tianjin High-tech Development Zone.

(2) Layout of inflatable wells and monitoring wells

In this field test, one gas-filled well and eight monitoring wells were set up. The cross-sectional and plane layout diagrams are shown in attached drawings 1 and 2, respectively. The depth of the specific well is determined according to the known on-site geological survey. The principle of the position layout of the gas-filled section in the gas-filled well is that it should be located in a soil layer with good permeability, such as silt, silt layer, etc., and there is seepage above and below the gas injection section. Relatively impermeable layer with a small rate; the principle of depth arrangement of monitoring wells is to meet the data acquisition near the aeration section and the upper part of the aeration section, and the principle of radial distance arrangement between monitoring wells and aeration wells is that monitoring wells with smaller distances Deep and similar to the depth of the middle part of the aerated section, the depth of the monitoring well with a large radial distance decreases, and is located at different depths between the upper part of the aerated section and the groundwater table.

The effective diameter of the inflatable well in this field experiment is 20cm, the depth of the inflatable well reaches the relatively impermeable layer below the aerated layer, and the length of the gas injection section is 1.5m.

The high-pressure air is introduced into the ground by installing an air-supply steel pipe in the center of the borehole, and a screen hole is made in the inflatable section (1.5m long). The whole steel pipe should be able to withstand the air pressure of 1.5bar; Therefore, it is necessary to install a threaded conversion joint at the ground outlet section. The inner diameter of the converted pipe is 1 inch, and the joint should be sealed to prevent air leakage; the underground section of the air supply pipe should be fixed to prevent movement during the inflation process. .

The pore treatment method between the borehole of the aeration well and the air supply steel pipe should be appropriate. Fill the pores of the aeration section with sand and gravel filter material, and fill the pores above the aeration section with sealing materials, such as clay or concrete.

There are 8 monitoring wells in total, the diameter of which is not less than 100mm, and they are respectively located in the radial direction of 8 equal parts of the circle with the gas-filled well as the center (i.e. due north, due south, due east, due west, northeast, southeast, northwest, southwest Direction), the radial distance between the monitoring wells in the south, the north, the east and the west is 1.0m from the gas-inflation well, and the radial distance between the monitoring wells in the other four directions and the gas-inflation well is 2.0m.

Depth layout requirements for monitoring wells: the depth of monitoring wells in the south and north directions should be greater than the depth of the upper end of the aerated section; the depth of monitoring wells in the northeast and southwest directions should be located in the middle of the first soil layer adjacent to the upper part of the aerated aquifer ; The depth positions of the monitoring wells in the four directions of due east, due west, southeast and northwest should be in the middle of the second soil layer above the aerated aquifer. The specific depth of the monitoring well is determined according to the soil layer distribution.

Three kinds of monitoring probes are installed at the bottom of each monitoring well, including TDR (diameter 5cm, length 15cm), earth pressure cell (diameter 2.8cm, thickness 1.0cm), piezometer (diameter 2.8cm, thickness 1.7cm). Firstly, the welded steel frame is used to fix the three kinds of probes. The data lines of the monitoring probes are protected to reach the ground through steel pipes with a diameter of 40mm. For sandy soil, test whether the monitoring probe can work normally. After the test is normal, use sealing material or undisturbed soil to backfill the gap between the monitoring borehole and the steel pipe. Try to prevent the high-pressure air filled into the ground from moving up along the monitoring well wall and steel pipe. happened.

(3) Inflatable system

In this example, an electric mobile air compressor is used to provide compressed air. The rated working pressure of this air compressor is 7.0 bar, the displacement is 4.2m ³ /min, and the diameter of the outlet pipe after conversion is 1 inch. During the use of the air compressor, the pressure should be increased step by step, and the pressure must not be reversed. The purpose is to prevent the pressure value from being too large to form an air leakage channel, which will cause the test to fail; at the same time, the pressure value should not be too small, otherwise the inflation effect will not be achieved. Therefore, the pressure value is required to increase step by step within a certain range.

(4) Control system

In this example, the control elements are all mounted on one panel. It consists of a primary pressure reducing valve, a filter, a high precision pressure reducing valve and a digital pressure gauge. According to the function, the filter can be divided into oil removal filter and dry filter. The invention only needs the oil removal filter. The control panel can achieve the purpose of filtering oil from compressed air, and can realize the primary decompression and high-precision adjustment of pressure, so that a series of pressure values can be obtained, and at the same time, the continuous actual pressure into the ground at different times and at various times can be measured. The size of the aquifer pressure.

(5) Acquisition system

Three monitoring probes were installed at the bottom of each monitoring well, including TDR (diameter 5cm, length 15cm), earth pressure cell (diameter 2.8cm, thickness 1.0cm), piezometer (diameter 2.8cm, thickness 1.7cm). First, the welded steel frame is used to fix the three kinds of probes. The data line of the monitoring probe is protected to the ground through a steel pipe with a diameter of 40mm, and the outlet of the steel pipe is sealed with a threaded joint; For sandy soil, test whether the monitoring probe can work normally. After the test is normal, use sealing material or undisturbed soil to backfill the gap between the monitoring borehole and the steel pipe, and prevent the high-pressure air filled underground from moving up along the monitoring well wall and steel pipe. A certain number of elevation observation piles are arranged within a certain range of the test area.

The TDR sensor is connected to the 8-channel soil moisture monitoring acquisition instrument through the signal transmission cable, and then the acquisition instrument is connected to the computer, so that the soil volumetric moisture content and soil temperature data can be obtained on the computer side; the soil pressure box and the piezometer pass through In the same connection mode, first connect the 16-channel strain acquisition instrument, and then connect the acquisition instrument to the computer to obtain the earth pressure value and pore water pressure value; for the acquisition of the elevation value, this embodiment uses the level instrument to cooperate with the elevation observation pile to obtain elevation value.

Claims (6)

1. a kind of field test device of manual inflation's method control surface subsidence, characterized in that including with lower part:

(1) well and monitoring well are inflated

Including 1 mouthful of inflation well, is arranged as required to several mouthfuls of monitoring wells, monitoring well is along inflation well periphery arrangement；

(2) inflation system

Gas replenishment process is realized by air compressor, for the operating pressure of air compressor depending on the depth of inflation well, depth is bigger, Operating pressure requires bigger；The compressed air require of air compressor is selected according to the pore size of inflation well, and aperture is bigger, Ask the compressed air require of air compressor bigger；

(3) control system

It is made of Primary relief valve, filter, high limit relay and digital pressure gauge, wherein filter includes oil removal filter And/or device for drying and filtering；

(4) acquisition system

TDR, soil pressure cell, osmometer are set in each monitoring well, further include：Using the monitoring soil moisture Acquisition Instrument in 8 channels Soil volumetric water content and soil temperature data are acquired, soil pressure force value and pore water are acquired using the strain acquirement instrument in 16 channels Pressure value obtains height value using spirit level cooperation leveling observation stake.

2. the field test device of manual inflation's method control surface subsidence as described in claim 1, characterized in that air compresses The pressure-air that machine generates is by inflating supplying gas steel pipe and import underground in well, and supplying gas, steel pipe inflation section is fabricated to sieve pore, Steel pipe of supplying gas is fixed in underground, prevents it from being moved during inflation.

3. the field test device of manual inflation's method control surface subsidence as described in claim 1, characterized in that monitoring well depth Degree arrangement requires：The depth of the monitoring well of due south and due north both direction should be greater than the depth of inflation section upper end；Northeast and southwest The monitoring well depth of both direction should be located close in the middle part of first soil layer on inflation water-bearing layer top；Due east, due west, the southeast and The monitoring well depth location of northwest four direction should be in the middle part of second soil layer on inflation water-bearing layer top, the specific depth of monitoring well Degree is determined according to clay distribution.

4. a kind of field testing procedure of manual inflation's method control surface subsidence, characterized in that include the following steps：

1) 1 mouthful of inflation well is set, is arranged as required to several mouthfuls of monitoring wells, monitoring well is along inflation well periphery arrangement；

2) air compressor is utilized to realize gas replenishment process, the operating pressure of air compressor is depending on the depth of inflation well, depth Bigger, operating pressure requires bigger；The compressed air require of air compressor is selected according to the pore size of inflation well, and aperture is got over Greatly, it is desirable that the compressed air require of air compressor is bigger；

3) gas that air compressor generates is led using Primary relief valve, filter, high limit relay and digital pressure gauge Enter and inflate underground, wherein filter includes oil removal filter and/or device for drying and filtering；

Data are measured using TDR, soil pressure cell, osmotic pressure, soil mass is acquired using the monitoring soil moisture Acquisition Instrument in 8 channels Product water content and soil temperature data acquire soil pressure force value and pore water pressure force value using the strain acquirement instrument in 16 channels, use Spirit level coordinates leveling observation stake to obtain height value.

5. the field testing procedure of manual inflation's method control surface subsidence as claimed in claim 4, characterized in that in inflation well Inflation section location arrangements principle be should be located at the preferable soil layer of permeability, the preferable soil layer of permeability be silt or silty sand ground, And inflating section, there are the smaller opposite aquicludes of permeability up and down；The depth arrangement principle of monitoring well should be met to inflation Nearby and the data acquisition on inflation section top, monitoring well and the radial distance arrangement principle of inflation well are apart from smaller monitoring to section Well is relatively deep, and close with the depth in the middle part of inflation section, and the depth of the big monitoring well of radial distance reduces, and positioned at inflation section At different depth between top and level of ground water.

6. the field testing procedure of manual inflation's method control surface subsidence as claimed in claim 4, characterized in that in air pressure During contracting machine use, pressure should increase step by step, cannot inversely apply pressure.