CN107165181A - It is a kind of that there is the subway foundation pit dewatering well for monitoring depressurization - Google Patents

Abstract

The invention discloses a subway foundation pit dewatering well with the function of monitoring decompression, which comprises two parts, an upper water supply layer and a lower water filtration layer, and a steel cage is arranged in the well to penetrate the water supply layer and the water filtration layer from top to bottom; the water supply layer A steel pipe is arranged inside the reinforcement cage, and clay is filled outside the reinforcement cage; the water filter layer is provided with a reinforcement water filter pipe inside the reinforcement cage, and double-layer nylon cloth is arranged outside the reinforcement cage and filled with filter material. The dewatering well device of the present invention not only realizes the real-time monitoring of groundwater changes, but also provides protection for emergency measures such as water recharge in the pit during the excavation of the foundation pit, avoiding uplift damage during the excavation of the foundation pit, and reducing the surrounding ground. , traffic and buildings, etc., to protect the safety of the surrounding environment and avoid unnecessary losses.

Description

A subway foundation pit dewatering well with monitoring and decompression function

technical field

The invention relates to the field of groundwater safety in the excavation of subway foundation pits, in particular to a dewatering well device for emergency monitoring of groundwater during the excavation of large foundation pits with high pressure water depth, in particular to a dewatering well device for subway foundation pits with the function of monitoring decompression Wells are used to detect changes in groundwater levels and deduce the stability of foundation pit excavation.

Background technique

At present, for deep and large foundation pits with highly confined water, the conventional measures are mainly to construct dewatering wells within the excavation range, and to pump groundwater before excavation of the foundation pit to solve the problem. This method has the disadvantage of wasting a large amount of groundwater resources, especially for water-scarce cities in the north represented by Beijing, which has great constraints.

In view of this, a method of excavating a foundation pit with water under the condition of no precipitation came into being. The real-time monitoring of the groundwater level during construction, the balance of the water level difference between the inside and outside of the foundation pit, and decompression and recharge in emergency situations have become It is the key to measure the stability of the foundation pit during the excavation process. This is a new problem arising in the construction of the new subway foundation pit excavation process. It is necessary to find a treatment method with short construction period, comprehensive functions, low cost, and safety and reliability. Problems that urgently need to be solved during the excavation process.

Contents of the invention

The purpose of the invention is to overcome the deficiencies in the prior art, and provide a subway foundation pit dewatering well with the function of monitoring decompression. The purpose of the present invention is achieved through the following technical solutions:

A subway foundation pit dewatering well with the function of monitoring decompression, comprising two parts: an upper water supply layer and a lower water filter layer, and a steel cage is arranged in the well to run through the water supply layer and the water filter layer from top to bottom; A steel pipe is arranged inside the cage, and clay is filled outside the steel cage; the water filter layer is provided with a steel filter pipe inside the steel cage, and a double-layer nylon cloth is arranged outside the steel cage and filled with filter material.

Further, the dewatering well is set above the groundwater level.

Further, the bottom of the precipitation well is 8.11~11.51m away from the groundwater level.

Further, the bottom of the precipitation well is 0.01-8.11m away from the groundwater level.

Further, the steel pipe of the water supply layer adopts Φ480 type, and the clay filled outside the reinforcement cage is closed and compacted.

Further, the reinforced water filter pipe of the water filter layer adopts a Φ508 type, and the double-layer nylon cloth is 40 mesh.

Further, the reinforcement cage includes longitudinal main ribs and transverse reinforcing ribs, the guiding ring of the reinforcing ribs is welded on the main ribs, the main ribs are of 9Φ14 type, and the reinforcing ribs are of Φ12@250 type.

Further, bamboo strips are bound outside the reinforcement cage on the filter layer, and the bamboo strips are distributed between every two main reinforcements.

Further, a filter screen is arranged between the reinforcement cage of the filter layer and the double-layer nylon cloth, the double-layer nylon cloth is wound outside the filter screen, and the filter material is filled outside the double-layer nylon cloth.

Further, the filter material is sand and gravel filter material, and the sand and gravel are graded gravel, and the mass ratio of the gradation is: gravel of 7 mm to 12 mm: gravel of 3 mm to 7 mm: sand = 45:25:30.

Beneficial effects of the present invention:

The subway foundation pit dewatering well with monitoring and decompression function of the present invention not only realizes real-time monitoring of groundwater changes by using the dewatering well device, but also provides guarantee for emergency measures such as water recharge in the pit during the excavation process of the foundation pit, avoiding It causes the uplift damage during the excavation of the foundation pit, thereby reducing the settlement impact of the surrounding ground, traffic and buildings, protecting the safety of the surrounding environment and avoiding unnecessary losses.

The invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

Description of drawings

Fig. 1 is a schematic diagram of the structure of the subway foundation pit dewatering well of the present invention (penetrating the water-resisting layer);

Fig. 2 is a schematic diagram of the structure of the subway foundation pit dewatering well of the present invention (does not penetrate the water-resistant layer);

Fig. 3 is the structural representation of reinforcement cage among the present invention;

Fig. 4 is A-A sectional view of Fig. 3;

Fig. 5 is a B-B sectional view of Fig. 3 .

Symbol Description:

1. Steel pipe; 2. Clay; 3. Reinforced water filter pipe; 4. Double-layer nylon cloth and filter material;

Soil distribution in strata: Ⅰ. House dregs; Ⅱ. Silt-fine sand; Ⅲ. Silty clay; Ⅳ. Pebbles.

detailed description

Example 1

As shown in Figure 1, a subway foundation pit dewatering well with monitoring and decompression functions includes two parts: the upper water supply layer and the lower water filter layer, and a steel cage 6 is installed in the well to run through the water supply layer and the water filter layer from top to bottom ; The water supply layer is provided with a steel pipe 1 inside the reinforcement cage 6, and clay 2 is filled outside the reinforcement cage; Cloth and filter material 4.

The dewatering well is set above the groundwater level, and the bottom of the dewatering well is 8.11-11.51m away from the groundwater level; the bottom of the dewatering well penetrates the underground aquifer 5 (8.11-11.51m away from the groundwater level).

In this example:

The steel pipe 1 of the water supply layer adopts Φ480 type, and the clay 2 filled outside the steel cage 6 is closed and compacted. The steel bar filter pipe 3 of water filter layer adopts Φ 508 type, and double-layer nylon cloth is 40 orders.

As shown in Figures 3 to 5, the reinforcement cage 6 includes longitudinal main ribs 8 and transverse reinforcing ribs 7, the guiding ring of the reinforcing ribs 7 is welded on the main ribs 8, the main ribs are 9Φ14 type, and the reinforcing ribs are Φ12@250 type .

Bamboo strips are bound outside the reinforcement cage on the filter layer, and the bamboo strips are distributed between every two main reinforcements. The bamboo strips are fixed on the reinforcing ribs by binding wires. After the reinforcement cage is covered with bamboo strips, a Φ50 pvc flower tube is installed on the outside, which is firmly fixed with the reinforcement cage. A filter mesh is arranged between the reinforcement cage of the filter layer and the double-layer nylon cloth, the double-layer nylon cloth is wound outside the filter mesh, and the filter material is filled outside the double-layer nylon mesh.

The filter material is sand and gravel filter material, and the sand and gravel are graded sand and gravel, and the mass ratio of the gradation is: gravel of 7 mm to 12 mm: gravel of 3 mm to 7 mm: sand = 45:25:30. The filter material should be round or sub-round. It is forbidden to use flaky or needle-shaped gravel. The mud content of the gravel (including stone powder) should be ≤3%. The gravel should be manually filled into the ring between the well pipe and the well hole. In the gap, the filling speed in all directions should be uniform, keep continuous, uniform and sufficient filling, and other sundries are strictly prohibited during the filling process, the allowable deviation of the filling amount is ±10%, and the filter material should be replenished in time after the well is washed. For filter material, the actual amount of filler is not less than 95% of the theoretically calculated amount.

Example 2

As shown in Figure 2, only the depth of the dewatering well in this embodiment is different from embodiment 1, and other features are the same as in embodiment 1. The bottom of the dewatering well is 0.01 ~ 8.11m away from the groundwater level line; Permeable underground water-resisting layer 5 (8.11~11.51m away from the groundwater level).

During the process of the project, the construction personnel used the water gauge to measure the water level in the dewatering well. According to the principle of the connector, the water level in the foundation pit is consistent with the water level in the dewatering well. Based on this, it can be judged whether the water level in the foundation pit exceeds the standard. Once it is found that the water level in the foundation pit exceeds the reasonable calculation value, the construction personnel will use the pump to pump the water out of the dewatering well in time, the water level in the dewatering well will drop, and the water pressure in the foundation pit will continuously squeeze the water in the foundation pit into the dewatering well and then be pumped out In this way, the water level in the foundation pit drops to the water level required by the project and the pumping is stopped, ensuring that the water pressure in the foundation pit remains within a reasonable range, avoiding the uplift damage of the foundation pit, and reducing the settlement of the surrounding ground, traffic and buildings. Played a role in protecting the environment and construction safety.

Claims (10)

1. A subway foundation pit dewatering well with monitoring decompression effect, is characterized in that: comprise two parts of the water supply layer of upper strata and the water filter layer of lower floor, in the well, reinforcement cage is set to run through water supply layer and water filter layer from top to bottom; The water supply layer is provided with a steel pipe inside the steel cage, and clay is filled outside the steel cage; the water filter layer is provided with a steel filter pipe inside the steel cage, and is provided with double-layer nylon cloth and filled with filter material outside the steel cage. 2. The subway foundation pit dewatering well according to claim 1, characterized in that: the dewatering well is arranged above the groundwater level. 3. The subway foundation pit dewatering well according to claim 2, characterized in that: the bottom of the dewatering well is 8.11-11.51m away from the groundwater level. 4. The subway foundation pit dewatering well according to claim 2, characterized in that: the bottom of the dewatering well is 0.01-8.11m away from the groundwater level. 5. The subway foundation pit dewatering well according to claim 1, characterized in that: the steel pipe of the water supply layer adopts Φ480 type, and the clay filled outside the reinforcement cage is closed and compacted. 6. The subway foundation pit dewatering well according to claim 1, characterized in that: the steel filter pipe of the filter layer adopts Φ508 type, and the double-layer nylon cloth is 40 mesh. 7. The subway foundation pit dewatering well according to claim 1, characterized in that: the reinforcement cage includes longitudinal main reinforcement and transverse reinforcement, the reinforcement guide ring is welded on the main reinforcement, the main reinforcement adopts 9Φ14 type, the The reinforcing rib mentioned above adopts Φ12@250 type. 8. The subway foundation pit dewatering well according to claim 7, characterized in that bamboo strips are bound outside the reinforcement cage located in the filter layer, and the bamboo strips are distributed between every two main reinforcements. 9. The subway foundation pit dewatering well according to claim 1, characterized in that: a filter screen is arranged between the steel cage of the filter layer and the double-layer nylon cloth, the double-layer nylon cloth is wound on the outside of the filter screen, and the filter material is filled in Double layer nylon mesh exterior. 10. The subway foundation pit dewatering well according to claim 1, characterized in that: the filter material is a sand filter material, and the gradation mass ratio is 7mm-12mm gravel: 3mm-7mm gravel: sand = 45:25:30.