CN106368165B - The dykes and dams seepage failure simulation test device of defect containing top and its construction method - Google Patents

Abstract

The invention relates to a dam seepage damage simulation test device with an upper defect and a construction method thereof. The device includes a model tank and a dam model arranged therein. The upper part of the dam model is provided with an arched simulated ant tunnel; the dam model is close to the downstream A spherical area is set near the simulated ant tunnel on the slope of the dam, and an artificial rainfall device is installed on the upper part of the model tank; multiple groups of monitoring sensors are buried near the simulated ant tunnel in the embankment model. The construction method of the device is as follows: firstly, clay is made into a soil sample, and an arched thin tube is buried on the upper part of the embankment model, and the soil sample is filled until it is higher than the thin tube, and then compacted, and then the soil sample around the thin tube is excavated into a spherical shape, and then backfilled The excavated soil sample makes the clay layer in the spherical area looser as it gets closer to the thin tube. After the filling is completed, the pre-buried thin tube is extracted to form a simulated ant tunnel, and multiple sets of monitoring sensors are set along the simulated ant tunnel. The invention can be used to study the dominant flow effect of the defect on the upper part of the homogeneous dam and the disaster mechanism of induced seepage damage.

Description

Seepage failure simulation test device and construction method of embankment with upper defect

technical field

The invention relates to a dam seepage failure simulation test device and a construction method thereof, belonging to the technical field of reservoir dam protection.

Background technique

According to statistics, 80.53% of the failed dams in my country are homogeneous earth dams, and 88% of the dams are less than 30m in height, and 40% of them are caused by engineering quality problems, aging and disrepair, and hidden dangers of biological damage. For example, the dam of Qinghaigou Reservoir broke due to reservoir water immersing into the extremely strong permeable layer connecting the upper and lower parts of the dam, causing seepage damage and bursting; The dam collapsed due to seepage damage caused by termite caves. The danger of the hidden danger defect in the upper part is that it is not easy to be detected by daily inspection and instrument monitoring, but its existence opens up a channel for the infiltration of reservoir water under the high reservoir water level, which can easily cause concentrated seepage damage, induce landslides and even dam failures.

The ancients said that "the harm caused by ants is difficult to detect hidden dangers", "a dike of a thousand miles collapses in an ant's nest". The catastrophic flood in the middle and lower reaches of the Yangtze River in 1998 caused 6,181 dangerous situations such as embankment piping and loose flooding in Hubei Province alone. After investigation, 80% of the dangerous hidden dangers were caused by termite tunnels. The ant tunnel is arched, with a diameter of about 10cm and a bottom width of about 8cm. into an embankment accident.

Model test research has the advantages of various environments and boundary conditions, simple operation, and high repeatability, and has become an important means of research on the failure mechanism of reservoir dams and river embankments. Generally speaking, the concentrated seepage induced by hidden danger defects shows the effect of unbalanced dominant flow, which in turn causes significant spatio-temporal changes in the seepage field of dams; The qualitative test of seepage is difficult to reflect the actual seepage behavior and its evolution and catastrophe process of dams with defects.

Contents of the invention

The technical problem to be solved by the present invention is: to provide a kind of seepage failure test device and construction method of a dam with an upper defect for studying the dominant flow effect of the upper defect of a homogeneous dam and its induced seepage damage mechanism and its construction method, so as to reveal the Predominant flow effect, spatiotemporal evolution of seepage field and seepage failure mechanism of lower homogeneous dams.

In order to solve the above-mentioned technical problems, one of the technical proposals proposed by the present invention is: a dam seepage failure simulation test device with upper defects, including a model tank made of transparent organic glass and a model tank made of clay layer. The dam model formed, the dam model is reduced in proportion to the dam to be simulated; the dam model includes the storage plate, the upstream dam slope, the dam crest and the downstream dam slope connected in sequence, and the upper part of the dam model is provided with a through dam The simulated ant tunnel of the upstream dam slope and the downstream dam slope, the dam model is provided with a weak area surrounding the simulated ant tunnel, and the clay layer in the weak area is closer to the simulated ant tunnel, the looser it is; the section of the simulated ant tunnel is Arched, with a diameter of less than 10 cm and a bottom width of less than 8 cm; the dam model is located near the simulated ant tunnel at the downstream dam slope and has a spherical area, and the clay layer in the spherical area is looser closer to the simulated ant tunnel , and the clay layer in the spherical area is also looser than the clay layer in the weaker area; the upper part of the model tank is provided with an artificial rainfall device, and the model tank is provided with a drainpipe for discharging the accumulated water on the downstream dam slope. The drainage pipe is higher than the slope toe of the downstream dam slope; multiple groups of monitoring sensors are buried near the simulated ant tunnel in the dam model, and each group of monitoring sensors includes a matrix suction sensor, a soil sample moisture content sensor and a pore water pressure sensor.

The test device of the present invention can simulate the osmotic damage caused by the dominant flow effect of the dam defect under complex hydraulic conditions, and form the upper defect by setting an arched simulated ant tunnel on the upper part of the dam model. When in use, the transparent plexiglass model tank can be used Real-time observation of the external deformation of the test dam model. The artificial rainfall device can control the rising process of the reservoir water level through the rainfall intensity according to the predetermined reservoir water level control conditions. The monitoring sensor group can monitor the volumetric moisture content of the soil samples inside the dam body and the defect in real time. , matric suction, pore water pressure change and hydraulic gradient distribution characteristics. Among them, the embankment model is filled according to the original soil density and water content, and the upper part of the defect is arranged and formed at the set position according to the set range and orientation according to the test requirements, and the enlarged weak area is set locally, so as to simulate the ant tunnel more realistically and more accurately. Accurately reflect the dangers and accidents caused by ant tunnels escaping from the backwater slope, such as loose leaching, piping, and landslides.

Preferably, the clay layer is made of clay excavated on-site for the dam to be simulated, and the particle size distribution and initial moisture content of the clay are the same as those of the undisturbed soil.

A further improvement of one of the above technical solutions is: a geotextile is pasted on the inner side of the side plate of the model groove at the downstream end of the embankment. In this way, when the drainage pipe discharges the accumulated water on the downstream dam slope, the soil layer on the downstream dam slope can be prevented from being carried away by the water flow.

A further improvement of one of the above technical solutions is: multiple pore water pressure sensors are embedded in the upstream dam slope.

A further improvement of one of the above technical solutions is: a camera is arranged on the upper part of the downstream dam slope. The process of seepage damage and external deformation of the downstream dam slope can be recorded by the camera for reference in subsequent research.

In order to solve the above-mentioned technical problems, the second technical solution proposed by the present invention is: a construction method of a dam seepage failure simulation test device containing upper defects. After filling the foundation and the bottom of the embankment model with this soil sample, tamp it tightly, and bury a thin tube with an arched cross-section at the preset position on the upper part of the embankment model, with a diameter of less than 10 cm and a bottom width of less than 8 cm; After the narrow tube reaches the predetermined height, compact it, then excavate the soil samples around the thin tube, expand the excavated area near the downstream dam slope to make the excavated area a spherical area, and refill the excavated soil sample, but reduce the number of tamping to make the spherical area The closer the clay layer in the area is to the thin tube, the looser it is, and then continue to fill the soil samples and tamp them to the design elevation, so that the dam model is scaled down according to the dam to be simulated; finally, the pre-buried thin tube is extracted to generate a simulated ant tunnel, and A weak area is generated around the simulated ant tunnel; during the embankment model filling process, multiple groups of monitoring sensors are set along the simulated ant tunnel, and each group of monitoring sensors includes a matrix suction sensor, a soil sample moisture content sensor and a pore water pressure sensor sensor.

Preferably, the center elevation of the simulated ant tunnel is 1/3 of the dam height from the dam crest.

Preferably, a geotextile is pasted on the inner side of the side plate of the model groove at the downstream end of the embankment.

Preferably, the clay is excavated from the site of the dam to be simulated, and then the clay is dried in a constant temperature oven, and a soil sample is prepared according to the particle gradation and initial moisture content of the undisturbed soil.

The beneficial effects brought by the present invention are as follows:

1) The present invention is a simulation test for seepage damage of homogeneous dams with upper defects (simulated ant tunnels). By pre-burying the arched thin tubes, the area around the arched thin tubes is excavated and backfilled, and the number of times of compaction is reduced. After the overall filling The arched thin tube is removed to form the upper defect of the embankment. In order to further increase the probability of seepage damage and instability, combined with the spatial distribution of the defect caused by biological erosion, the defect is set at a certain angle towards the downstream dam slope, and the defect is set on the side close to the downstream dam slope. Partially increase the weak area around the arch to form a spherical enlarged peripheral weak area, so that the test can effectively simulate the weak layer of penetrating defects upstream and downstream of the dam body, ant tunnels caused by biological invasion, and main nests, etc., so as to be stable and effective. Ground simulation of the dominant flow effect and its induced dam body seepage failure and dam slope instability can reveal the dominant flow effect of a homogeneous dam with an upper defect, the spatiotemporal evolution of seepage field and the mechanism of seepage failure. The calculation model of the whole process of non-equilibrium seepage in homogeneous dams with defects (loose leaching-predominant flow effect-piping-collapse of the upper part of the dam body and landslide of the downstream dam slope) is of great value.

2) The present invention is based on the wrecked projects (Qinghaigou Reservoir, Sichuan Dalugou Reservoir, typical dikes in the middle and lower reaches of the Yangtze River), and according to the similarity theory, soil samples are configured, and the upper defects are arranged according to the defect simulation method described to ensure the success rate of the test and the adaptability of the results; in order to increase the hydraulic head of the weak layer to increase the osmotic pressure in its vicinity, and prevent the reservoir water or river water from overflowing, the center of the defective layer is about 1/3 of the dam height from the dam crest; the plexiglass The drainage pipe on the right side of the model trough is slightly higher than the downstream toe to simulate the water level behind the dam or ponding behind the embankment.

3) The present invention quantitatively obtains the multi-scale seepage behavior parameter changes of local dam hidden dangers and the whole dam body by including multiple sets of monitoring sensors including high-sensitivity matrix suction sensor, soil sample water content sensor and pore water pressure sensor, among which pore water pressure Meters, matrix suction meters, and volumetric water content meters are densely arranged in the area near the upper defect, so as to grasp the seepage status inside the dam body and the local defect in real time, and obtain its evolution law.

4) The present invention has the advantages of simple principle, convenient operation, quick monitoring, multiple utilization, and high test error tolerance rate.

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing.

Fig. 1 is a schematic structural diagram of a dam seepage failure simulation test device with an upper defect in an embodiment of the present invention.

Fig. 2 is a schematic cross-sectional view of the simulated ant tunnel in the embodiment of the present invention.

Detailed ways

Embodiment one

This embodiment relates to the dam seepage failure simulation test device with upper defects, as shown in Figure 1 and Figure 2, the device includes a model tank 1 made of transparent plexiglass and a dam set in the model tank 1 and made of a clay layer Model 12, the dam model 12 is scaled down with the dam to be simulated; the dam model 12 includes the reservoir plate AB, the upstream dam slope BC, the dam crest CD and the downstream dam slope DE that are connected in sequence, and the upper part of the dam model 12 is provided with a penetrating dam upstream The simulated ant tunnel 6 of the dam slope CD and the downstream dam slope DE, the embankment model 12 is provided with a weak area 7 surrounding the simulated ant tunnel 6, and the clay layer of the weak area 7 is looser closer to the simulated ant tunnel 6; The section is arched; the embankment model 12 is provided with a spherical area 8 near the simulated ant tunnel 6 at the downstream dam slope DE, the clay layer of the spherical area 8 is looser closer to the simulated ant tunnel 6, and the spherical area 8 The clay layer is also looser than the clay layer in the weak area 7, thereby forming a partially enlarged weak area for simulating the main nest in the ant tunnel 6.

Model groove 1 is made of front, rear, left, right and base plate five plexiglass plates among the present embodiment, and front and back two plexiglass plates are identical, thickness 5cm, length 300cm, height 120cm, left and right two plexiglass plates are identical, The thickness is 5cm, the length is 150cm, and the height is 120cm. The thickness of the plexiglass bottom plate is 5cm, the length is 300cm, and the width is 160cm; The thickness of the soil sample below the surface is 20cm, the center of the simulated ant tunnel 6 is 25cm above the dam crest, the bottom of the simulated ant tunnel 6 is 6cm wide, and the sides are 2cm high.

The upper part of the model tank 1 is provided with an artificial rainfall device 2, and the artificial rainfall device 2 includes a water supply tank 3 and a nozzle 13 communicated with the water supply tank 3 through a pipeline, and is controlled on and off by a valve. The pipeline connecting the water supply tank 3 and the nozzle 13 is provided with a flow meter 14 for accurately controlling the amount of rainfall, and the intensity of the rainfall is adjusted through a pressurized water pump 15 and a valve.

The model tank 1 is provided with a drainage pipe 4 for discharging accumulated water on the downstream dam slope DE. The drainage pipe 4 is higher than the foot of the downstream dam slope and can simulate the water level behind the dam or the accumulated water behind the embankment.

Multiple groups of monitoring sensors are buried near the simulated ant tunnel 6 in the dam model 12 , and each group of monitoring sensors includes a matrix suction sensor 11 , a soil sample water content sensor 9 and a pore water pressure sensor 10 . In this embodiment, there are ten groups of monitoring sensors, among which seven groups of monitoring sensors are buried equidistantly along the simulated ant tunnel 6; and three groups of monitoring sensors are equidistantly arranged along the downstream dam slope DE. In addition, one pore water pressure sensor 10 is respectively embedded in the dam heel and the middle part of the upstream dam slope BC.

This embodiment can also be improved as follows:

1) The clay layer is made of clay excavated on-site for the embankment to be simulated, and the particle size distribution and initial water content of the clay are the same as those of the undisturbed soil. This can more truly reflect the real situation of the dam to be simulated.

2) The inner side of the side plate of the model groove at the downstream end of the embankment is pasted with a geotextile. In this way, when the drainage pipe discharges the accumulated water on the downstream dam slope, the soil layer on the downstream dam slope can be prevented from being carried away by the water flow.

3) Cameras are arranged on the upper part of the downstream dam slope DE. The process of seepage damage and external deformation of the downstream dam slope can be recorded by the camera for reference in subsequent research.

In this embodiment, the embankment with upper defects can be more realistically simulated through the above settings, and the above embankment can be tested by simulating rainfall. During the test, multiple sets of monitoring sensors can be used to detect the parameter evolution process of the embankment, and the dangers such as loose leaching, piping, and landslides caused by the escape of ant tunnels from the backwater slope can be visually observed, providing a basis for follow-up research.

The test process of this embodiment is as follows:

1) Fill the water supply tank 3 with water, open the valve and the self-metering flowmeter 14, start the pressurized water pump 15, record the reading of the flowmeter 14, and control the amount of rainfall until the set rainfall amount is reached, start to rain, and record The initial value of the flowmeter, and open the valve 5 of the drain pipe 4 to remove the accumulated water on the downstream dam slope DE, and stop the rain when the water level of the reservoir reaches 1/3 of the dam height;

2) Record the readings of twelve micro-pore water pressure sensors, ten soil sample moisture content sensors, and ten matrix suction sensors at intervals of 30 minutes. At the same time, the external high-definition camera continuously records the changes of the upstream dam slope until the end of the test ;

3) Wait for 2 days, fill the water supply tank 3 with water, start the artificial rainfall device 2 again, adjust the amount of rainfall, and keep the rainfall intensity at the BC surface upstream of the dam slope. Count the readings of 14, continue to rain until the water level reaches the top of the defect inlet, reduce the rainfall intensity, and keep the water level rising slowly, but not to the top;

4) Record the readings of each sensor at intervals of 10 minutes until seepage damage or landslide damage occurs on the downstream dam slope, then stop the rainfall, record the readings of each sensor again, and the test ends.

Embodiment two

This example is the construction method of the dam seepage failure simulation test device with upper defects in Example 1. First, clay is made into a soil sample, and the soil sample is used to fill the foundation of the dam model in a model tank made of transparent plexiglass. and the bottom after tamping, bury a thin tube with an arched cross-section at the preset position on the upper part of the embankment model, the diameter of which is less than 10 cm, and the bottom width is less than 8 cm; continue to fill the soil sample until it is higher than the predetermined height of the thin tube, then tamp it, and then dig Remove the soil samples around the thin tube, expand the excavated area near the downstream dam slope to make the excavated area a spherical area, and refill the excavated soil samples, but reduce the number of times of compaction so that the closer the clay layer in the spherical area is to the thin tube, the more After loosening, continue to fill the soil samples and compact them to the design elevation, so that the dam model is scaled down according to the dam to be simulated; finally, the pre-buried thin tubes are extracted to generate simulated ant tunnels, and at the same time, the nearby soil Such activities create weak areas around the simulated ant tunnel; during the embankment model filling process, multiple groups of monitoring sensors are set along the simulated ant tunnel, each group of monitoring sensors includes a matrix suction sensor, a soil moisture content sensor and A pore water pressure sensor.

In this embodiment, the clay is preferably excavated from the dam to be simulated on site, and then the clay is dried in a constant temperature oven, and a soil sample is prepared according to the particle gradation and initial moisture content of the undisturbed soil.

The central elevation of the simulated ant tunnel is preferably 1/3 of the dam height from the dam crest, and a geotextile is pasted inside the side plate of the model groove at the downstream end of the dam.

The present invention is not limited to the specific technical solutions described in the above embodiments. Besides the above embodiments, the present invention can also have other implementation modes. All technical solutions formed by equivalent replacement are within the scope of protection required by the present invention.

Claims (9)

1. a kind of dam seepage damage simulation test device containing upper defect, it is characterized in that: comprise the model groove that transparent plexiglass is made and be arranged in described model groove and adopt the embankment model that clay layer is made, described embankment model and The dam to be simulated is scaled down; the dam model includes successively connected reservoirs, upstream dam slopes, dam crests and downstream dam slopes, and the upper part of the dam model is provided with a simulation ant that runs through the dam upstream dam slope and the downstream dam slope. The dam model is provided with a weak area surrounding the simulated ant tunnel, and the clay layer in the weak area is looser closer to the simulated ant tunnel; the section of the simulated ant tunnel is arched, and its diameter is less than 10 cm. Width is less than 8 centimetres; Described embankment model is positioned at the simulated ant tunnel place near the downstream dam slope and is provided with a spherical area, and the clay layer of this spherical area is looser closer to this simulated ant tunnel, and the clay layer of this spherical area is also relatively The clay layer in the weak area is looser; the upper part of the model tank is provided with an artificial rainfall device, and the model tank is provided with a drainage pipe for discharging the accumulated water of the downstream dam slope, and the drainage pipe is higher than the slope foot of the downstream dam slope; Multiple groups of monitoring sensors are buried near the simulated ant tunnel in the dam model, and each group of monitoring sensors includes a matrix suction sensor, a soil sample water content sensor and a pore water pressure sensor. 2 . The device for simulating seepage failure of a dam with upper defects according to claim 1 , wherein a geotextile is pasted on the inner side of the side plate of the model groove at the downstream end of the dam. 3 . 3. The seepage damage simulation test device for a dam with an upper defect according to claim 1, wherein a plurality of pore water pressure sensors are embedded in the upstream dam slope. 4. The device for simulating seepage failure of a dam with an upper part defect according to claim 1, characterized in that a camera is arranged on the upper part of the downstream dam slope. 5. according to claim 1, contain the upper defect embankment seepage damage simulation test device, it is characterized in that: described clay layer adopts the clay excavated on-site of the embankment to be simulated to make, and the particle gradation and initial water content of described clay The particle size distribution and initial water content of the undisturbed soil are the same. 6. a construction method containing the top defect embankment seepage damage simulation test device of claim 1, is characterized in that: Make a soil sample from clay, use the soil sample to fill the foundation and bottom of the dam model in the model tank made of transparent plexiglass, and tamp it down, and bury a thin tube with an arched cross section at the preset position on the upper part of the dam model. Its caliber is less than 10 cm and its base width is less than 8 cm; Continue to fill the soil samples to a predetermined height higher than the thin tube, then tamp them down, then excavate the soil samples around the thin tube, expand the excavated area near the downstream dam slope to make the excavated area a spherical area, and refill the excavated soil sample. However, reducing the number of times of compaction makes the clay layer in the spherical area looser as it gets closer to the thin tube, and then continues to fill the soil samples and tamp them to the design elevation, so that the dam model is scaled down according to the dam to be simulated; finally, the pre-buried thin tube is extracted to generate Simulate an ant tunnel, and generate a weak area around the simulated ant tunnel; During the filling process of the embankment model, multiple groups of monitoring sensors are set along the simulated ant tunnel, and each group of monitoring sensors includes a matrix suction sensor, a soil sample moisture content sensor and a pore water pressure sensor. 7. The construction method of the seepage damage simulation test device for dams with upper defects according to claim 6, characterized in that: the central elevation of the simulated ant tunnel is 1/3 of the dam height from the dam crest. 8 . The method for constructing a simulation test device for seepage failure of a dam with upper defects according to claim 6 , wherein a geotextile is pasted on the inner side of the side plate of the model groove at the downstream end of the dam. 9 . 9. The construction method of the embankment seepage failure simulation test device containing the upper defect according to claim 6, characterized in that: the clay is excavated from the embankment site to be simulated, and then the clay is dried in a constant temperature box, according to Particle gradation and initial moisture content of undisturbed soil Preparation of soil samples.