CN111255439A - Self-heating optical fiber device and method for judging sealing quality of clay ball on side wall of pressure reduction well - Google Patents

Abstract

The invention relates to a self-heating optical fiber device and a self-heating optical fiber method for judging clay ball sealing quality of a side wall of a depressurization well. Compared with the prior art, the method can conveniently and quickly evaluate the quality of the clay ball hole sealing in the well forming process of each pressure reduction well by using an optical fiber temperature measurement technology before the foundation pit descends, and can quickly locate the defect position if the clay ball hole sealing has a seepage defect so as to guide the pressure reduction well to carry out seepage treatment on the confined water.

Description

Self-heating optical fiber device and method for judging the sealing quality of clay balls on the sidewall of pressure-relief wells

technical field

The invention belongs to the technical fields of geological engineering, geotechnical engineering and foundation pit engineering, and relates to wellbore leakage monitoring, in particular to a self-heating optical fiber device and method for judging the sealing quality of clay balls on the sidewall of a depressurization well.

Background technique

In the construction environment with high groundwater level, well point dewatering is an important technical measure in the construction of earthwork, foundation and foundation engineering. It can reduce the lateral displacement and settlement of the soil on the slope, stabilize the slope, eliminate the quicksand, and reduce the uplift of the base soil, so that the foundation and foundation engineering construction under the natural groundwater can avoid the influence of groundwater, provide relatively dry construction conditions, and also It can reduce the amount of earthwork, shorten the construction period, improve the quality of the project and ensure the safety of construction. However, due to the limitation of construction conditions in the process of depressurization well formation, the sealing quality of clay balls is often not ideal, resulting in the leakage of confined water at the bottom of the well pipe through the clay balls to the surface through the pipe wall, and long-term seepage may even cause the well to leak. It becomes a seepage channel and cannot play a role in reducing blood pressure. At present, the detection method for the sealing quality of the clay ball is not considered in the construction process of the pressure-reducing well. After the clay ball is sealed and the well is cleaned, the pump tube can be installed to test pumping water. It is urgent to determine the location of the defect caused by the sealing of the clay ball. , and deal with the defects in time to prevent the failure of the depressurization well to carry out research.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a self-heating optical fiber device and method for judging the sealing quality of the clay ball on the sidewall of the depressurization well in order to overcome the above-mentioned defects of the prior art. The self-heating optical cable is used to judge the sealing quality of the clay ball on the sidewall of the pressure-reduction well by measuring the abnormal temperature change of the optical cable laid on the sidewall of the pressure-reduction well.

The object of the present invention can be realized through the following technical solutions:

The first aspect of the present invention provides a self-heating optical fiber device for judging the sealing quality of the clay ball on the sidewall of the depressurization well, including a heating type armored temperature measuring optical cable and a distributed optical fiber temperature sensing system (DTS). The armored temperature-measuring optical cable surrounds the side wall of the depressurization well in a spiral shape from bottom to top, and the top is exposed on the surface and is connected to the distributed optical fiber temperature sensing system. The DTS system can realize real-time temperature monitoring and high/low temperature alarms.

Preferably, along the length direction from the bottom end of the depressurization well, each time a preset length increases, the heating type armored temperature measuring optical cable surrounds the outer circumference of the sidewall of the depressurization well.

Preferably, the heating type armored temperature measuring optical cable has a flat oval cross section, and is composed of a central bundle tube, a sensing optical fiber built in the central bundle tube and a water blocking filler, an insulating layer surrounding the central bundle tube, and a surrounding It is composed of an outer sheath that is outside the insulating layer and is embedded with a heating copper wire reinforcement.

Preferably, the heating type armored temperature measuring optical cable is fixed outside the side wall of the depressurization well by iron wires or iron sheets, and the iron wires or iron sheets are directly welded on the side wall of the depressurization well.

A second aspect of the present invention provides a method for judging the sealing quality of clay balls on the sidewall of a pressure-reducing well, using the device, and the pressure-reducing well is composed of a plurality of butt-jointed well pipes, and the method includes the following steps:

S1: Arrange the heated armored temperature measuring optical cable on a section of the well pipe at the bottom, and reserve the length that can be connected to the surface, and reel the reserved optical cable on the top of the well pipe;

S2: When this section of well pipe is hoisted into the dewatering well, after the two sections of well pipe are connected, the reserved optical cable is fixed on the pipe wall of this section of well pipe in a spiral shape when the next section of well pipe is hoisted, and the operation is repeated until Well pipe hoisting is completed;

S3: When the depressurization well is running, in the process of pumping and depressurizing, the heating type armored temperature measurement optical cable is energized and heated up, and the exposed heating type armored temperature measurement optical cable is connected to the distributed optical fiber temperature sensing system to detect the heating According to the abnormal temperature rise of the armored temperature measuring optical cable at different positions of the pressure-reduction well, the seepage position of the outer wall of the well pipe is determined according to the abnormal temperature, and then the sealing quality of the clay ball on the side wall of the pressure-reduction well is judged.

Preferably, the pressure-reducing well is a pressure-reducing well that has been used in engineering, the wellhead is 0.5m above the bottom surface, the water filter pipe of the confined water layer is provided with externally filled gravel, and other positions are provided with fillers outside the well wall Clay ball seal.

Preferably, along the length direction from the bottom of the depressurization well, for each additional meter of length, the heating type armored temperature measuring optical cable surrounds the outer circumference of the sidewall of the depressurization well. From the mouth of the well pipe, the length of the optical cable corresponds to the position of the well pipe. The relationship is:

Among them: L represents the length of the optical cable from the nozzle of the well pipe; H represents the length of the well pipe from the nozzle of the well pipe; R represents the actual radius of the well pipe.

Preferably, in step S3, during the process of pumping and depressurizing, the heating type armored temperature measuring optical cable is connected to 50-150V alternating current, and the temperature of the optical cable is raised to 30-70°C after the power is turned on.

Compared with the prior art, the present invention has the following beneficial effects:

The invention can use the optical fiber temperature measurement technology to easily and quickly evaluate the quality of the clay ball sealing during the well completion process of each pressure-reducing well before the foundation pit is dewatered. Pressurized water leakage disposal work. When the foundation pit is dewatered, it is necessary for the excavation of the foundation pit to lower the water level below the excavation surface. The introduction and installation of a self-heating optical cable measuring device in the construction process of the depressurization well can greatly facilitate the observation of the sealing quality of the clay ball, and can provide new ideas for the construction process of foundation pit dewatering.

Description of drawings

Fig. 1 is the schematic diagram of the self-heating optical fiber device of the present invention;

FIG. 2 is a schematic cross-sectional view of the heating-type armored temperature-measuring optical cable of the present invention.

In the figure, 1 is the decompression well, 2 is the heated armored temperature measuring optical cable, 3 is the iron sheet, 4 is filled with clay balls, 5 is filled with gravel, 6 is the distributed optical fiber temperature sensing system, and 7 is the sensing fiber , 8 is the central bundle tube, 9 heating copper wire reinforcement, 10 insulating layer, 11 outer sheath.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

Example 1

A self-heating optical fiber device for judging the sealing quality of the clay ball on the sidewall of the depressurization well, as shown in Figure 1, includes a heated armored temperature measurement optical cable 2 and a distributed optical fiber temperature sensing system 6, and the heated armored temperature measurement The optical cable 2 spirally surrounds the side wall of the depressurization well 1 from bottom to top, and the top end is exposed on the surface and is connected to a distributed optical fiber temperature sensing system 6 (DTS in the prior art). DTS system can realize real-time temperature monitoring and high/low temperature alarm

In this embodiment, the depressurization well 1 adopts the depressurization well 1 that has been used in engineering. The specific well pipe size and length are comprehensively considered according to factors such as the actual pressure-bearing water head and precipitation on the site, and the actual construction design scheme shall prevail. It should be 0.50m above the ground to prevent surface sewage from seeping into the well. Filled gravel 5 is arranged outside the water filter pipe of the confined water layer, and filled clay balls 4 are arranged outside the well wall at other positions for sealing.

The heating type armored temperature measuring optical cable 2 (self-heating optical cable) has a flat oval cross section, and consists of a central bundle tube 8 (preferably a seamless steel pipe), a sensing optical fiber 7 built into the central bundle tube 8 and a water blocking filler , an insulating layer 10 surrounding the central bundle tube 8 and an outer sheath 11 (preferably made of PE material) surrounding the insulating layer 10 and embedded with a heating copper wire reinforcement 9. The optical cable has good bending resistance, scratch resistance and signal transmission performance, and can be widely used in engineering inspection. The self-heating optical cable is arranged in a spiral shape from the bottom of the well tube around the outer wall of the well tube of the depressurization well. Along the length direction, the heating-type armored temperature-measuring optical cable 2 surrounds the outer circumference of the side wall of the depressurization well 1 every time a preset length is added. It is further preferred that from the bottom of the depressurization well along the length direction, each time the length increases by one meter, the heating type armored temperature measuring optical cable surrounds the outer circumference of the sidewall of the depressurization well, and the corresponding relationship between the length of the optical cable and the position of the well tube is calculated from the mouth of the well pipe. for:

Among them: L represents the length of the optical cable from the nozzle of the well pipe; H represents the length of the well pipe from the nozzle of the well pipe; R represents the actual radius of the well pipe.

In this embodiment, the heating-type armored temperature measuring optical cable 2 is preferably fixed outside the side wall of the depressurization well 1 through iron wires or iron sheets 3, which play a fixing role, and the iron wires or iron sheets 3 are directly welded on the side wall of the depressurization well 1.

A method for judging the sealing quality of the clay ball on the sidewall of a pressure-reducing well, using the above device, the design depth of the pressure-reducing well 1 is determined according to the depth of the underground confined water aquifer in the actual project site, and the depth of the pressure-reducing well 1 will generally reach several tens of meters. When hoisting and hoisting the well pipe, it needs to be hoisted in sections. During the hoisting and hoisting process of the well pipe, it is welded at the sectional position, and the optical cable is fixed on the side wall of the well pipe during the hoisting and hoisting process of the well pipe.

The method includes the following steps:

S1: Arrange the heated armored temperature measuring optical cable on a section of the well pipe at the bottom, and reserve the length that can be connected to the surface, and reel the reserved optical cable on the top of the well pipe;

S2: When this section of well pipe is hoisted into the dewatering well, after the two sections of well pipe are connected, the reserved optical cable is fixed on the pipe wall of this section of well pipe in a spiral shape when the next section of well pipe is hoisted, and the operation is repeated until Well pipe hoisting is completed;

S3: When the depressurization well is running, in the process of pumping and depressurizing, the heating type armored temperature measurement optical cable is energized and heated up, and the exposed heating type armored temperature measurement optical cable is connected to the distributed optical fiber temperature sensing system to detect the heating According to the abnormal temperature rise of the armored temperature measuring optical cable at different positions of the pressure-reduction well, the seepage position of the outer wall of the well pipe is determined according to the abnormal temperature, and then the sealing quality of the clay ball on the side wall of the pressure-reduction well is judged.

In the preferred step S3 in this embodiment, the heating type armored temperature measuring optical cable is connected to 50-150V alternating current (the specific voltage is determined according to the actual length of the self-heating optical cable) during the pumping and depressurization process, and the temperature of the optical cable rises to 30- 70°C.

During the entire optical cable laying process, attention should be paid to avoid the optical cable being stretched or being squeezed by the well wall to cause the optical cable to break.

The invention can use the optical fiber temperature measurement technology to easily and quickly evaluate the quality of the clay ball sealing during the well completion process of each pressure-reducing well before the foundation pit is dewatered. Pressurized water leakage disposal work. When the foundation pit is dewatered, it is necessary for the excavation of the foundation pit to lower the water level below the excavation surface. The introduction and installation of a self-heating optical cable measuring device in the construction process of the depressurization well can greatly facilitate the observation of the sealing quality of the clay ball, and can provide new ideas for the construction process of foundation pit dewatering.

The foregoing description of the embodiments is provided to facilitate understanding and use of the invention by those of ordinary skill in the art. It will be apparent to those skilled in the art that various modifications to these embodiments can be readily made, and the generic principles described herein can be applied to other embodiments without inventive step. Therefore, the present invention is not limited to the above-mentioned embodiments, and improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should all fall within the protection scope of the present invention.

Claims (8)

1. The self-heating optical fiber device for judging the clay ball sealing quality of the side wall of the depressurization well is characterized by comprising a heating type armored temperature measuring optical cable (2) and a distributed optical fiber temperature sensing system (6), wherein the heating type armored temperature measuring optical cable (2) spirally surrounds the side wall of the depressurization well (1) from bottom to top, and the top end of the heating type armored temperature measuring optical cable is exposed out of the ground and is connected with the distributed optical fiber temperature sensing system (6).

2. The self-heating optical fiber device for judging the sealing quality of the clay ball on the side wall of the depressurization well according to claim 1, wherein the heating type armored temperature measuring optical cable (2) surrounds the outer circumference of the side wall of the depressurization well (1) every time a preset length is added along the length direction from the bottom end of the depressurization well (1).

3. The self-heating optical fiber device for judging clay ball sealing quality of the side wall of a depressurization well according to claim 1, wherein the cross section of the heating type armored temperature measuring optical cable (2) is in a flat ellipse shape and comprises a central beam tube (8), a sensing optical fiber (7) and a water-blocking filler which are arranged in the central beam tube (8), an insulating layer (10) surrounding the central beam tube (8) and an outer sheath (11) surrounding the insulating layer (10) and embedded with a heating copper wire reinforcement (9).

4. The self-heating optical fiber device for judging the clay ball sealing quality of the side wall of the depressurization well according to claim 1, wherein the heating type armored temperature measuring optical cable (2) is fixed outside the side wall of the depressurization well (1) through an iron wire or an iron sheet (3), and the iron wire or the iron sheet (3) is directly welded on the side wall of the depressurization well (1).

5. A method for judging clay ball sealing quality of a side wall of a depressurization well, which is characterized in that the device of any one of claims 1 to 4 is adopted, and the depressurization well (1) is composed of a plurality of butted well pipes, and the method comprises the following steps:

s1: arranging a heating type armored temperature measuring optical cable on a section of well pipe at the bottom end, reserving the length which can be connected to the ground surface, and coiling the reserved optical cable on the top end of the section of well pipe;

s2: after the section of well pipe is hoisted and placed into the dewatering well and two sections of well pipes are butted, fixing the reserved optical cable on the pipe wall of the section of well pipe in a spiral shape along with the next section of well pipe during hoisting and placing, and repeating the operation until the hoisting and placing of the well pipe are completed;

s3: when the pressure reducing well operates, in the process of pumping water and reducing pressure, the heating type armored temperature measuring optical cable is electrified to be heated, the heating type armored temperature measuring optical cable exposed out of the ground surface is connected with the distributed optical fiber temperature sensing system, the heating abnormality of the heating type armored temperature measuring optical cable at different positions of the pressure reducing well is detected, the seepage position of the outer wall of the well pipe is determined according to the heating abnormality, and then the sealing quality of clay balls on the side wall of the pressure reducing well is judged.

6. The method for judging the clay ball sealing quality of the side wall of the pressure reducing well according to claim 5, wherein the pressure reducing well which is started to be used in engineering is used, the well mouth is 0.5m higher than the bottom surface, gravel filling materials are arranged outside a water filtering pipe of a pressure-bearing water layer, and clay ball sealing is arranged outside the well wall at other positions.

7. The method for judging clay ball sealing quality of a sidewall of a depressurization well according to claim 5, wherein for every one meter of increase in length along the length direction from the bottom end of the depressurization well, the heating type armored temperature measuring optical cable surrounds the outer circumference of the sidewall of the depressurization well, and the corresponding relation between the optical cable length and the well pipe position is as follows from the mouth of the well pipe:

wherein: l represents the cable length from the wellhead; h represents the length of the well pipe from the mouth of the well pipe; r represents the actual well pipe radius.

8. The method for judging the clay ball sealing quality of the sidewall of the depressurization well according to claim 5, wherein in the step S3, the heating type armored temperature measuring optical cable is electrified with an alternating current of 50-150V in the process of pumping water and depressurizing, and the temperature of the optical cable is raised to 30-70 ℃ after the alternating current is electrified.

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