CN101787702A - Strong vacuum dewatering method - Google Patents

Abstract

The invention relates to a powerful vacuum dewatering dewatering method, which relates to the technical field of underground engineering dewatering, and solves the technical problems of small influence radius and low water yield of pumping in the prior art. The method is characterized in that: a filter is sleeved on the pipe wall of the bottom section of the well pipe of the dewatering well, and a water inlet connected to the filter is opened on the pipe wall of the bottom section of the well pipe; a water pump is installed in the well pipe , and make the water inlet higher than the water inlet of the well pipe; a liquid level controller is built into the well pipe to control the operation of the pump; the top of the well pipe is sealed with a well cover to prevent leakage, and a vacuum pump is installed on the ground, and a vacuum pump is installed on the well cover. A vacuum tube connecting the suction port of the vacuum pump and the inner cavity of the well pipe; the through holes on the well cover are sealed with anti-leakage; then the well pipe is pumped by the vacuum pump, so that the well pipe presents a high vacuum and negative pressure state. The method provided by the invention can shorten the pumping operation period and improve the water yield.

Description

Powerful vacuum dewatering precipitation method

technical field

The invention relates to the technology of underground engineering dewatering, in particular to the technology of a powerful vacuum dewatering method.

Background technique

In the process of underground engineering construction in high water level areas, the method of precipitation is often used to reduce the water content of the soil layer, thereby improving the consolidation strength of the soil, reducing the supporting force of the confined water, and ensuring the construction safety of the underground engineering. Among them, tube well dewatering is the most widely used dewatering method. It has the characteristics ^of large precipitation ^depth and ^wide application in formations. Various strata in the order of 10 ³ m ³ /d.

Traditional tube well dewatering relies on gravity to make groundwater collect into the tube well, and the water collected in the tube well is discharged through the pump. This precipitation method does not have the effect of freeing bound water from the gravitational force of soil particles, and can only pump out a small amount of gravity water, which has a poor precipitation effect on clay, silty clay, and clayey silt layers with low permeability coefficients. With the development of technology, the tube well dewatering has introduced the auxiliary means of vacuum negative pressure, which accelerates the collection of groundwater into the well, and improves the drainage efficiency and precipitation effect.

However, in the existing vacuum dewatering method, due to the difficulty in ensuring the tightness of the tube well structure, there are obvious technical weaknesses in the tube well structure, and a strong negative pressure gravitational relationship cannot be formed and always maintained between the well tube inner cavity and the dewatering target layer , the vacuum negative pressure in the well pipe is only about 0.06MPa in the early stage of the precipitation operation, and can only be maintained at 0.04MPa or lower in the middle and late stages of the precipitation operation. Therefore, the gravity of the vacuum negative pressure is not enough to get rid of the difficult-to-pump bound water Soil particles, the water outlet effect is still unsatisfactory; for example, a concentric double-casing vacuum deep well point disclosed in the patent No. ZL200610118379.1 has the above defects, especially for the main object of dewatering and precipitation— - Saturated cohesive soil layer and silty soil layer, the tube well precipitation water yield rate of the invention is not high, the influence radius of pumping is small, the pumping operation period is long, and the water content of the precipitation target layer cannot be greatly reduced for the purpose of dewatering and precipitation. Target.

Contents of the invention

In view of the defects existing in the above-mentioned prior art, the technical problem to be solved by the present invention is to provide a pumping pump with a large influence radius, a short pumping operation period, and high water yield in saturated cohesive soil layers and powdery soil layers with small permeability coefficients. High-efficiency powerful vacuum dewatering precipitation method.

In order to solve the above technical problems, a powerful vacuum dewatering precipitation method provided by the present invention is characterized in that the specific steps are as follows:

1) Set a filter on the wall of the bottom section of the well pipe of the dewatering well, and open a water inlet connected to the filter on the wall of the bottom section of the well pipe;

2) Drill and set the precipitation hole on the ground, and the diameter of the hole is larger than the designed outer diameter of the filter;

3) Hoist the bottom section of the well pipe into the drilled hole slot, and place it in the center of the hole slot, and then add well pipe joints to the bottom section of the well pipe one by one until the well pipe The bottom reaches the set hole bottom elevation;

Wherein, a tube well backwash hole is provided on the pipe wall of the top section of the well pipe, and the tube well backwash hole is sealed with a valve to prevent leakage;

4) Fill the filter material between the well pipe and the wall of the hole, and between the filter and the wall of the hole;

5) Install a water pump in the well pipe, and make its suction port higher than the water inlet of the well pipe;

6) A liquid level controller is built into the well pipe, and the control liquid level of the liquid level controller is set according to the height of the suction port of the pump;

7) Seal the top of the well pipe with a well cover to prevent leakage, and open a through hole on the well cover to lead out the power cord of the liquid level controller, the cable of the pump and the drain pipe connected to the drain of the pump, and install a vacuum pump on the ground. A vacuum tube connected to the inner cavity of the well pipe is installed on the well cover;

Among them, the through holes on the well cover are sealed with anti-leakage;

Among them, the power line of the liquid level controller is connected with the automatic switch of the pump;

8) Carry out the well flushing operation through the backwash hole of the tube well. After the well flushing operation is completed, close the valve of the backwash hole of the tube well, and fill water-proof clay or clay balls above the filter material;

9) Connect the vacuum tube to the suction port of the vacuum pump;

10) Turn on the vacuum pump to evacuate the well pipe, so that the well pipe presents a state of high vacuum and negative pressure;

11) When the water level in the well pipe rises to the set high water level, the liquid level controller controls the pump to turn on, pumps the collected water in the well pipe out of the well pipe, and when the water level in the well pipe drops to the set low water level, the liquid level controller controls the water pump Close; repeat this step until the precipitation operation is completed.

Further, in step 1, an upper extension filter is sheathed on the wall of the well pipe above the filter.

Further, in the step 1, an upper extension vacuum tube is added inside the upper extension filter, and at least one sealable air inlet is provided at the bottom end of the upper extension vacuum tube.

Further, in the step 9, the vacuum tube of the upper extension section is also connected to the suction port of the vacuum pump.

Further, in step 7, a vacuum gauge is also installed on the vacuum tube on the well cover.

Further, in step 11, when the filter material is silted up, inject high-pressure water into the well pipe through the backwash hole of the tube well to clean the filter material, or inject high-pressure air into the well pipe to clean the filter material when the clear water level in the well pipe meets the conditions.

In the powerful vacuum dewatering method provided by the present invention, the top of the well pipe of the dewatering well is sealed with a well cover to prevent leakage, and a vacuum tube is installed on the well cover. Vacuum and negative pressure state, thus generating a strong gravitational force to force the bound water to get rid of the binding force of soil particles, so that the bound water and gravity water can quickly collect into the tube well; Created conditions, and can always maintain a vacuum negative pressure of not less than 0.08MPa during the whole process of dewatering and precipitation, which not only accelerates the collection of gravity water into the tube well, but also has a good separation of bound water with strong binding force with soil particles capacity, thereby improving the water yield and efficiency of the soil layer, especially in the saturated cohesive soil layer and silty soil layer with a small permeability coefficient, the water yield rate can be increased by 5 to 20 times; in addition, it also significantly expands the structure of the tube well. The influence radius of pumping; on the premise of reducing the water content index of the precipitation target layer, the construction period of pumping operation is shortened.

Description of drawings

Fig. 1 is a schematic diagram of a powerful vacuum dewatering and dewatering method according to an embodiment of the present invention.

Detailed ways

The embodiments of the present invention will be described in further detail below in conjunction with the accompanying drawings, but the present embodiments are not intended to limit the present invention, and any similar structures and similar changes of the present invention should be included in the protection scope of the present invention.

As shown in Figure 1, a powerful vacuum dewatering precipitation method provided by the embodiment of the present invention is characterized in that,

Specific steps are as follows:

1) Set a filter 2 on the wall of the bottom section of the well pipe 1 of the dewatering well, and open a water inlet 3 connected to the filter 2 on the wall of the bottom section of the well pipe 1;

Among them, according to the anti-seepage environment of the boundary of the foundation pit project and the limited time of pre-pumping before excavation of the foundation pit, an upper extension filter can also be set on the well pipe wall above the filter 2, and the upper extension section Add an upper extension vacuum tube to the inside of the filter;

Wherein, the bottom end of the vacuum tube of the upper extension section is provided with at least one air inlet hole which can be closed;

Among them, the type of filter 2 can be selected according to the physical characteristic index of the precipitation soil layer, such as a round hole filter tube filter with a net, a bridge filter tube filter with a net, or a wire wrapped filter with a round hole with a net, etc. ;

2) Drilling and setting the precipitation hole on the ground, the hole diameter of the hole is larger than the design outer diameter of the filter 2 or more than 300mm, and the quality control standard of the hole should meet the requirements of the design document;

3) Hoist the bottom pipe joint of the well pipe 1 into the drilled hole, and place it in the center of the hole with the help of a centering device, and then add well pipes to the bottom pipe joint of the well pipe 1 one by one Pipe joints until the bottom of the well pipe reaches the set hole bottom elevation;

Wherein, a tube well backwashing hole is provided on the pipe wall of the top section of the well pipe 1, and the tube well backwashing hole is sealed with a valve to prevent leakage;

4) Fill the filter material between the well pipe 1 and the wall of the hole, and between the filter 2 and the wall of the hole;

5) Install a water pump 5 in the well pipe 1, and make its water intake higher than the water inlet 3 of the well pipe 1;

6) A liquid level controller 6 is built into the well pipe 1, and the control liquid level of the liquid level controller 6 is set according to the height of the suction port of the water pump 5;

7) Seal the top of the well pipe 1 with a well cover to prevent leakage, and open a through hole on the well cover to lead out the power cord of the liquid level controller 6, the cable of the water pump 5 and the drain pipe connected to the water outlet of the water pump 5, and install it on the ground. A vacuum pump, a vacuum tube 7 connected to the inner cavity of the well pipe is installed on the well cover, and a vacuum gauge is installed on the vacuum tube 7;

Among them, the through holes on the well cover are sealed with anti-leakage;

Wherein, the power line of liquid level controller 6 is connected with the automatic switch of water pump 5;

8) Carry out the well flushing operation through the backwash hole of the tube well. After the well flushing operation is completed, close the valve of the backwash hole of the tube well, and fill water-proof clay or clay balls above the filter material;

9) Connect the vacuum tube 7 to the suction port of the vacuum pump. If the upper extension vacuum tube is selected, connect the upper extension vacuum tube to the suction port of the vacuum pump;

10) Turn on the vacuum pump to pump air into the well pipe 1, so that the inside of the well pipe is in a state of high vacuum and negative pressure, thereby generating a strong gravitational force to force the bound water to break away from the binding force of the soil particles, so that the bound water together with the gravity water can quickly collect into the well pipe;

Among them, the pressure in the well pipe is displayed by the vacuum gauge. When the pressure in the well pipe displayed by the vacuum gauge rises to the set negative pressure value within a short period of time, it means that the vacuum system including the well pipe is in good condition;

11) When the water level in the well pipe 1 rises to the set high water level, the liquid level controller 6 controls the pump 5 to turn on, and pumps the collected water in the well pipe 1 out of the well pipe. When the water level in the well pipe 1 drops to the set low water level At the same time, the liquid level controller 6 controls the water pump 5 to close; repeat this step until the dewatering operation is completed;

In step 11 of the embodiment of the present invention, when the filter material is silted up, inject high-pressure water into the well pipe to clean the filter material through the backwash hole of the tube well, or inject high-pressure air into the well pipe to clean the filter material when the clean water level in the well pipe meets the conditions.

In the embodiment of the present invention, if the water yield is significantly greater than that of the traditional tube well structure at the initial stage of operation, it is confirmed that the seepage between the groundwater in the dewatering target layer and the well pipe is in a smooth state, and the negative pressure in the well pipe has an impact on the groundwater body in the formation. Negative pressure gravitational effect has been produced; if the vacuum gauge continues to show a high degree of vacuum in the early stage of precipitation operation, and the amount of water collected in the well pipe is large, it can be judged that the precipitation effect of the tube well has appeared; in the early stage of precipitation operation, although the well pipe is still Maintain a high vacuum negative pressure state, but the amount of water collected in the well pipe will gradually decrease, indicating that the water content of the soil in the precipitation target layer has gradually decreased, which is a normal phenomenon.

In the embodiment of the present invention, the dynamic water level curve in the surrounding soil layer with the well pipe as the center is gentler than the dynamic water level curve of the traditional vacuum tube well dewatering method.

Claims (6)

1. effective vacuum dewatering method is characterized in that concrete steps are as follows:

1) sheathed strainer on the end of precipitation well well casing section tube coupling tube wall, and on the end of well casing section tube coupling tube wall, offer the water inlet that is communicated with strainer;

2) be drilled with the precipitation hole slot on ground, the drilling diameter of hole slot is greater than the design external diameter of strainer;

3) end section tube coupling with well casing lifts in the hole slot that is drilled with, and is placed on the hole slot center, adjunction well casing tube coupling one by one on the end of well casing section tube coupling then, until the well casing bottom arrive set the hole at the bottom of absolute altitude;

Wherein, the top section tube coupling tube wall of well casing is provided with pipe well recoil hole flushing, and this pipe well recoil hole flushing is with a Valve leakageproofing hermetic seal;

4) between well casing and the hole slot wall, insert filtrate between strainer and the hole slot wall;

5) suction pump is installed in well casing, and is made its water sucking mouth be higher than the water inlet of well casing;

6) in well casing, insert fluid level controller, and the control liquid level of fluid level controller is set according to the height of suction pump water sucking mouth;

7) the well casing top is sealed with a well lid anti-gas-leak, on well lid, offer the gutter that through hole is drawn the cable of the power line of fluid level controller, suction pump and connected the suction pump outfall, at floor mounted one vacuum pump, the vacuum tube of a connected well tube cavity is installed on well lid;

Wherein, the through hole on the well lid all adopts the anti-gas-leak sealing;

Wherein, the power line of fluid level controller is connected with the automatic switch of suction pump;

8) carry out clean-out service by pipe well recoil hole flushing, the valve sealing of hole flushing that after clean-out service finishes pipe well recoiled, and above filtrate, insert roof clay or clay ball;

9) air entry of vacuum tube and vacuum pump is connected;

10) open vacuum pump well casing is bled, make to present the condition of high vacuum degree negative pressure state in the well casing;

11) open when water level in the well casing rises to when setting high water level fluid level controller control suction pump, extract the water that compiles in the well casing out well casing, reduce to when setting low water stage fluid level controller control suction pump when water level in the well casing and close; Repeat this step, finish until the precipitation operation.

2. method according to claim 1 is characterized in that: in the described step 1, and the section of prolonging strainer on also sheathed on the well casing tube wall above the strainer.

3. method according to claim 2 is characterized in that: in the described step 1, the bottom of the section of prolonging vacuum tube is provided with at least one closed air inlet on setting up the section of prolonging vacuum tube, be described in the inboard of the last section of prolonging strainer.

4. method according to claim 3 is characterized in that: in the described step 9, with on the air entry of the section of prolonging vacuum tube and vacuum pump also connect in the lump.

5. method according to claim 1 is characterized in that: in the described step 7, a vacuum meter is installed also on the vacuum tube on the well lid.

6. method according to claim 1, it is characterized in that: in the described step 11, when the filtrate silting, in well casing, injects water under high pressure by pipe well recoil hole flushing and clean filtrate, or the clear water water level in well casing injects pressure-air cleaning filtrate when eligible in well casing.

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