Seepage control system for in-situ test wells in deep overburden layers

Abstract

The present invention relates to the field of geotechnical engineering, in particular to a seepage control system for an in-situ test well in a deep overburden layer, which effectively solves the seepage control during the excavation and test stages of a large in-situ test well in a deep overburden layer. The seepage control system includes an undisturbed test sampling area, and a diaphragm wall structure is arranged around the periphery of the undisturbed test sampling area. It includes at least one dewatering well, and the dewatering well is arranged between the diaphragm wall structure and the undisturbed test sampling area. The dewatering well includes an outer pipe with water inlet holes arranged on the wall surface, a deep well pump arranged in the outer pipe, and a water level monitoring system. The deep well pump is connected to the outside through pipelines. The present invention is particularly applicable to the in-situ test well test in a deep overburden layer.

Description

Technical Field

[0001] The present invention relates to the field of geotechnical engineering, and in particular to a seepage control system for an in-situ test well in a deep overburden layer. Background Art

[0002] Deep soil mechanics is currently a difficult point in geotechnical engineering research. There are large differences in the physical and mechanical parameters of soil obtained by different conventional test methods, and the applicability of in-situ tests is poor. By using a large in-situ test well with a diameter exceeding 9m, the soil can be directly excavated, and in-situ tests and undisturbed sampling can be carried out in the well to accurately obtain the physical and mechanical parameters of deep soil. However, while safely excavating the large in-situ test well, it is necessary to ensure the seepage stability and relative undisturbedness of the soil in the well, the hydraulic gradient of the soil in the well does not exceed the critical hydraulic gradient, and avoid structural damage to the soil. The water level in the well is dynamically adjusted according to the excavation depth and is close to the elevation of the excavation surface to ensure that the water content of the soil below the excavation surface remains relatively unchanged. At the same time, the seepage control measures should minimize the disturbance to the test soil. Therefore, the large in-situ test well has extremely high requirements for seepage control, especially in a deep overburden layer mainly composed of sand. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a seepage control system for an in-situ test well in a deep overburden layer that effectively solves the seepage control during the excavation and test stages of a large in-situ test well in a deep overburden layer.

[0004] The technical solution adopted by the present invention to solve its technical problems is: a seepage control system for an in-situ test well in a deep overburden layer, including an undisturbed test sampling area, a diaphragm wall structure is circumferentially arranged around the undisturbed test sampling area, including at least one precipitation well, the precipitation well is arranged between the diaphragm wall structure and the undisturbed test sampling area, the precipitation well includes an outer pipe with water inlet holes arranged on the wall surface, a deep well pump arranged in the outer pipe, and a water level monitoring system, and the deep well pump is connected to the outside through a pipeline.

[0005] Further, the water level monitoring system includes a water level monitoring sensor for defining the lowest water level and a limiter for defining the highest water level.

[0006] Further, the precipitation well is arranged at the diaphragm wall joint of the diaphragm wall structure.

[0007] Further, a filter screen is arranged at the water inlet hole of the outer pipe.

[0008] Further, the filter screen is sleeved on the outer wall surface of the outer pipe.

[0009] Further, reinforcing bars are arranged between the filter screen and the outer wall surface of the outer pipe.

[0010] Further, galvanized aluminum wire is wound around the outside of the filter screen.

[0011] Furthermore, the precipitation well is arranged in the borehole.

[0012] Furthermore, the water level monitoring system and the deep well pump are connected to the automatic control system.

[0013] Furthermore, the precipitation wells are evenly arranged around the undisturbed test sampling area.

[0014] The beneficial effects of the present invention are as follows: during actual use, since a water level monitoring system is provided in the precipitation well, when the seepage of the soil mass is excessive, the deep well pump is started to pump water to reduce the seepage water accumulation; when the seepage of the soil mass approaches the bottom critical value, the operation of the deep well pump is stopped, so as to ensure precise seepage control and ensure the reduction of the disturbance of the seepage to the test soil mass. The present invention is particularly applicable to the in-situ test well test in deep overburden layers. Description of the Drawings

[0015] Figure 1 is the top view of the present invention.

[0016] Figure 2 is the side cross-sectional view of the present invention.

[0017] Figure 3 is the schematic diagram of the positional relationship between the precipitation well and its surroundings of the present invention.

[0018] Figure 4 is the cross-sectional view of the precipitation well of the present invention.

[0019] Figure 5 is the cross-sectional view of the precipitation well of the present invention.

[0020] The labels in the figure are: precipitation well 1, borehole 11, gravel 12, water level monitoring sensor 13, deep well pump 14, water pipe 15, limiter 16, manifold interface 17, water surface 18, water inlet hole 111, galvanized aluminum wire 112, mat reinforcement 113, filter screen 114, outer pipe 115, undisturbed test sampling area 2, diaphragm wall structure 3, diaphragm wall joint 31, soil outside the well 4, phreatic line 5, pipeline 6, manifold 61, circuit 611, water pipe 612, frequency converter 62, control system 63, sump 64, electromagnetic flowmeter 65. Detailed Embodiments

[0021] The present invention will be further described below with reference to the drawings.

[0022] As Figures 1 to 5The seepage control system of the in-situ test well with deep overburden layer shown in the figure includes an undisturbed test sampling area 2, and a diaphragm wall structure 3 is arranged around the periphery of the undisturbed test sampling area 2. It includes at least one precipitation well 1, and the precipitation well 1 is arranged between the diaphragm wall structure 3 and the undisturbed test sampling area 2. The precipitation well 1 includes an outer pipe 115 with water inlet holes 111 arranged on the wall surface, a deep well pump 14 arranged in the outer pipe 115, and a water level monitoring system. The deep well pump 14 is connected to the outside through a pipeline 6. In order to better control the water level range, it is preferred that the precipitation wells 1 are evenly arranged around the undisturbed test sampling area 2.

[0023] As Figure 2 shown, through the dynamic control of the deep well pump 14 and the water level monitoring system, it is ensured that the soil seepage is within a reasonable range, thereby reducing the disturbance of the seepage to the test soil and ensuring the accuracy of the test. Generally, in order to accurately control the upper and lower limits of the water level, it is preferred that the water level monitoring system includes a water level monitoring sensor 13 for defining the lowest water level and a limiter 16 for defining the highest water level. In actual setting, it is preferred that the precipitation well 1 is arranged at the diaphragm wall joint 31 of the diaphragm wall structure 3. In addition, the depth and number of the precipitation wells 1 are obtained by seepage calculation, and the diameter should not be too large to avoid using rotary drilling rig construction. The selection of the deep well pump 14 should consider the flow rate and head, and it is preferably placed at the bottom of the precipitation well 1. The water level monitoring device is preferably placed at the bottom of the precipitation well 1 and staggered from the deep well pump 14 by a certain distance to improve the accuracy of the data. Corresponding to the system, a frequency converter 62, a control system 63, a sump 64, and an electromagnetic flowmeter 65 are also provided. As Figure 1 shown, after passing through the distributor 61, a circuit 611 and a water pipe 612 are separated. Among them, the circuit 611 is connected to the frequency converter 62 and the control system 63, and the water pipe 612 is connected to the electromagnetic flowmeter 65 and the sump 64. Among them, the diameter of the distributor 61 should meet the requirements of the calculated flow rate. The electromagnetic flowmeter 65 is connected to the control system and can directly collect data. When the system is running abnormally, the water level may exceed or be lower than the warning water level. At this time, the control system needs to give an alarm, and at least two methods of on-site buzzer alarm and network push alarm are adopted.

[0024] To prevent the soil from clogging the water inlet hole 111, it is preferred that a filter screen 114 is provided at the water inlet hole 111 of the outer pipe 115, so as to ensure the normal function of the water inlet hole 111. Generally, it is preferred that the filter screen 114 is sleeved on the outer wall surface of the outer pipe 115, and the selection of the filter screen 114 is calculated according to the particle size distribution of the soil layer. To ensure that the filter screen obtains sufficient support and prevent the soil from damaging the filter screen, it is preferred that a reinforcing pad 113 is provided between the filter screen and the outer wall surface of the outer pipe 115. Further, it is preferred that a galvanized aluminum wire 112 is wound around the outside of the filter screen 114. Generally, it is preferred that the dewatering well 1 is arranged in the borehole 11. The water level monitoring system and the deep well pump 14 are connected to the automatic control system to achieve dynamic control.

[0025] In actual use, the test is generally carried out according to the following steps: a. Implement multiple dewatering wells in the well through a drilling rig, and the dewatering wells are arranged at the joints of the diaphragm wall of the in-situ test well; b. Insert a steel perforated pipe wrapped with a filter screen into the borehole; c. Install a submersible deep well pump at the bottom of the steel perforated pipe; d. Connect the limiter and the frequency converter to the deep well pump to control the start-stop and operating power of the deep well pump, and connect them to the control system; e. Install a water level monitoring device in the well and connect it to the control system; f. Connect the distributor to each water pump and uniformly connect them to the sump, and install an electromagnetic flowmeter connected to the control system at the pipe orifice; g. Set the starting water level and warning water level of the limiter according to the dynamic change of the excavation depth; h. The control system adjusts the limiter and the frequency converter according to the data fed back by the water level monitoring sensor and the electromagnetic flowmeter, adjusts the water level by starting and stopping the water pump through the limiter, controls the dewatering rate of the water pump through the frequency converter, and the control system issues an alarm when the actual water level exceeds or is lower than the warning water level. The present invention conducts dewatering by installing submersible deep well pumps in multiple steel perforated pipe dewatering wells wrapped with filter screens, and realizes precise control of the water level of the large-scale in-situ test well by setting up a control system integrating a limiter, a frequency converter, an electromagnetic flowmeter, a water level monitoring device and a warning device, providing necessary guarantees for the safe excavation of the in-situ test well, the seepage stability of the soil in the well and the relative in-situ state.

Claims

1. The seepage control system of the in-situ test well in deep overburden layer, including the undisturbed test sampling area (2), is characterized in that a diaphragm wall structure (3) is arranged around the periphery of the undisturbed test sampling area (2). Comprising at least one dewatering well (1), the dewatering well (1) is arranged between the diaphragm wall structure (3) and the undisturbed test sampling area (2), the dewatering well (1) includes an outer pipe (115) with water inlet holes (111) provided on the wall surface, a deep well pump (14) arranged inside the outer pipe (115), and a water level monitoring system, and the deep well pump (14) is communicated with the outside through a pipeline (6); the water level monitoring system includes a water level monitoring sensor (13) for defining the lowest water level and a stopper (16) for defining the highest water level, the dewatering well (1) is arranged at the diaphragm wall joint (31) of the diaphragm wall structure (3), a filter screen (114) is arranged at the water inlet hole (111) of the outer pipe (115), the filter screen (114) is sleeved on the outer wall surface of the outer pipe (115), a spacer bar (113) is arranged between the filter screen and the outer wall surface of the outer pipe (115), a galvanized aluminum wire (112) is wound around the filter screen (114), and the dewatering wells (1) are uniformly arranged around the undisturbed test sampling area (2).

2. The seepage control system of the in-situ test well for deep overburden layer according to claim 1, characterized in that: The dewatering well (1) is arranged in a borehole (11).

3. The seepage control system of the in-situ test well for deep overburden layer as described in claim 1, characterized in that: The water level monitoring system and the deep well pump (14) are communicated with an automatic control system.

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