CN-122016604-A - Ultra-large vertical compression horizontal seepage erosion experiment box device and experiment method

CN122016604ACN 122016604 ACN122016604 ACN 122016604ACN-122016604-A

Abstract

The invention discloses an ultra-large vertical compression horizontal seepage erosion experiment box device and an experiment method, and belongs to the field of civil engineering and hydraulic engineering. The device body is a high-strength test box body, the internal dimension of a sample bin is 1000mm multiplied by 1000mm, the maximum vertical load reaches 10MPa, a top cover is provided with a peripheral air bag and an impermeable strip, self-adaptive sealing under ultrahigh pressure is realized, 64 pressure sensors are arranged in a three-dimensional layered array in the sample, and a wireless-wired cooperative fine monitoring layout is formed by matching with wired sensors of a side wall and a water inlet and outlet bin. The test method eliminates the size effect and the side wall effect by combining a multi-index system such as a hydraulic gradient, a hydraulic gradient non-uniformity coefficient, a water head distribution uniformity index and the like through the standard steps of sample loading, sealing, loading, saturation, gradually increasing hydraulic gradient, data acquisition and test ending, accurately simulates the actual stress and seepage state of a soil body, realizes the perception and visualization of the progressive erosion process in the sample caused by seepage, and provides a high-efficiency and scientific device and method for researching the seepage characteristics of the soil body of a deep and thick coverage layer.

Inventors

WANG GANG
LI HAN
JIN WEI

Assignees

重庆大学
中国电建集团成都勘测设计研究院有限公司

Dates

Publication Date: 20260512
Application Date: 20260313

Claims (10)

1. The ultra-large vertical compression horizontal seepage erosion experiment box device is characterized in that the main body of the device is a high-strength experiment box body, the high-strength experiment box body is of a steel structure with the maximum vertical load of 10MPa, a sample bin used for placing detection samples is arranged in the high-strength experiment box body, the internal size of the sample bin is 1000mm multiplied by 1000mm, one side of the sample bin is provided with an upstream water inlet bin, the other side of the sample bin is provided with a downstream water outlet bin, the upstream water inlet bin is provided with a water inlet, the downstream water outlet bin is provided with a water outlet funnel used for collecting fine particle soil samples, the top of the sample bin is provided with a top cover, an adaptive sealing structure used for inhibiting leakage after high-pressure deformation is arranged between the top cover and the box body, a plurality of wireless micro pressure sensors are arranged in an array, the wireless micro pressure sensors are used for monitoring pore water pressure changes at different positions in a soil body, the sensing and visualizing the progressive development process of seepage flow sensors in the soil body, the upstream water inlet bin is provided with a water outlet, and the water outlet is provided with a water outlet.
2. The ultra-large vertical compression horizontal seepage erosion experiment box device according to claim 1, wherein the self-adaptive sealing structure comprises a peripheral air bag arranged on the periphery of a top cover, an air bag groove for fixing the peripheral air bag and an air inlet for inflating the peripheral air bag are arranged at the bottom of the top cover, the peripheral air bag is inflated through the air inlet, and the peripheral air bag is tightly contacted with the inner wall of a sample bin, the top cover and the upper surface of the sample after being inflated, so that sealing is realized and leakage of the sample box after high-pressure deformation is inhibited.
3. The ultra-large vertical compression horizontal seepage erosion experiment box device according to claim 1, wherein a seepage inhibition wall for inhibiting dominant seepage is arranged between the sample bin and the upstream water bin and between the sample bin and the downstream water bin, the seepage inhibition wall is two side walls through which inflow water in the sample bin passes, and transparent resin air bags for inhibiting side wall seepage are fixedly arranged on the two side walls.
4. The ultra-large vertical compression horizontal seepage erosion experiment box device according to claim 1, wherein a first retaining plate and a second retaining plate are arranged between an upstream water bin and a downstream water bin in the sample bin, and the first retaining plate and the second retaining plate are porous mesh plates which are parallel and perpendicular to the water flow direction.
5. The ultra-large vertical compression horizontal seepage erosion experiment box device is characterized in that a plurality of wireless miniature pressure sensors are wireless miniature piezoresistive pore water pressure sensors and are packaged in a high-strength metal shell with a water permeable hole so as to be embedded into a sample in a three-dimensional layered array mode of a water inlet end section, a middle section and a water outlet end section.
6. The ultra-large vertical compression horizontal seepage erosion experiment box device according to claim 1, wherein the wireless micro piezoresistive pore water pressure sensor is integrally used as coarse particles in a soil sample, embedded in the soil sample according to the arrangement mode of the coarse particles of the soil body, and directly participates in the construction of a soil body framework.
7. A test method based on the ultra-large vertical compression horizontal seepage erosion experimental box device according to any one of claims 1 to 6, which is characterized by comprising the following steps: (1) Before the test starts, soil samples are layered and loaded into sample bins according to a test scheme, each layer of loaded samples is provided with a wireless miniature piezoresistive pore water pressure sensor according to a set mode, and the wireless miniature piezoresistive pore water pressure sensor is coordinately embedded into a soil sample to be used as coarse particles to participate in a seepage test; (2) Placing the top cover above the sample, and inflating the peripheral air bags on the top cover through the air port to enable the air bags to be in close contact with the side wall of the sample bin and the soil sample; (3) Connecting the sample box with a water supply system, supplying water into the sample bin through the water supply system, stopping supplying water after the water in the sample bin is full, loading the sample through a vertical loading system, stabilizing the load after the load reaches a preset value, and waiting for the saturation of the soil sample; (4) After the soil sample is saturated, adding a sedimentation flocculant into a sedimentation tank, and connecting a water outlet funnel at the downstream of the sample box with the sedimentation tank; (5) Opening a wireless miniature piezoresistive pore water pressure sensor, a side wall pore water pressure sensor, a water inlet pore water pressure sensor and a water outlet pore water pressure sensor, starting a test after waiting for 100 pore pressure meter readings to be stable, gradually increasing hydraulic ramp down through a water supply system, recording the change of the pore pressure meter readings in each stage, monitoring the permeation development of a sample through data inversion, and stopping increasing the hydraulic ramp down after the hydraulic ramp down of a test scheme is reached or a soil sample is damaged; (6) After the test is finished, stopping supplying water, unloading, removing the top cover after the water in the sample bin is completely discharged, photographing the sample, recording, and then removing the sample.
8. The method of claim 7, wherein the hydraulic gradient is calculated by inverting the seepage development in the soil body through the change of the indication of the pore water pressure sensor: In the method, i is hydraulic gradient, delta H is the indication difference of the coaxial two-hole pressure gauge and L is the distance between the coaxial two-hole pressure gauge.
9. The test method according to claim 7, wherein the non-uniformity coefficient is determined by a hydraulic gradient And head distribution uniformity index Determining the seepage uniformity, wherein: Is the maximum hydraulic gradient in the cross section, As the average hydraulic gradient of the section, the judgment standard is as follows: less than or equal to 1.2, even seepage and no dominant seepage, 1.2< <1.5, The seepage is substantially uniform, the local dominant seepage; not less than 1.5, remarkably uneven seepage and dominant seepage development; The water head is actually measured by a jth pore pressure meter in the section, The average water head of the section is obtained, and n is the number of the section inner pore pressure gauges; The judgment standard is as follows: <3%, even water head distribution, stable seepage and less than or equal to 3% Less than or equal to 8 percent, more uniform water head distribution and general seepage stability; 8%, the water head distribution is seriously uneven, and dominant seepage is obvious.
10. The method according to claim 7, wherein the dominant seepage channel development intensity is quantified by the dominant seepage channel development degree D: to correspond to the cross-sectional average hydraulic gradient, The hydraulic gradient at the measuring point is determined as follows: Less than or equal to 10% of D is an unoccupied seepage channel, 10% < D less than or equal to 30% is the preliminary development of the dominant seepage channel, and D >30% is the complete penetration of the dominant seepage channel; By a variation function Analyzing the spatial correlation of the hydraulic gradient, judging the spatial distribution characteristics of dominant seepage, In order to be a spatial distance from each other, For the hydraulic gradient at the position xi, The method is characterized in that the method is a sample logarithm with a distance h, if a variation function rapidly tends to be stable along with the increase of the distance, the spatial correlation of a seepage field is strong, seepage is uniform, and if fluctuation is severe and irregular, the dominant seepage is proved to develop randomly and the spatial distribution is uneven.

Description

Ultra-large vertical compression horizontal seepage erosion experiment box device and experiment method Technical Field The invention belongs to the technical field of civil engineering and hydraulic engineering, and particularly relates to an ultra-large vertical compression horizontal seepage erosion experiment box device and a test method, which are suitable for testing the seepage characteristics of a deep coverage soil body under different stress conditions and exploring the evolution rule of soil body seepage erosion and particle loss. Background Along with the deep advancement of the construction of the water conservancy and hydropower engineering in China to the west, a large number of heavy and large projects need to be built on a deep and thick covering layer with a complex hierarchy. The deep-thickness coverage soil body is easy to generate phenomena of infiltration erosion, particle loss and the like under the long-term seepage effect, and the safety and stability of a dam foundation and the whole engineering are directly threatened, so that the system research is carried out on the infiltration characteristics of the deep-thickness coverage soil body, and the method is a key premise for guaranteeing the safety construction and long-term operation of the engineering. At present, students at home and abroad design various seepage corrosion test devices capable of providing high-overburden stress conditions, which are used for exploring the seepage corrosion characteristics of the soil body of the deep overburden layer, but the existing devices still have obvious defects, and are difficult to meet the actual test requirements of engineering; secondly, the existing device can provide limited overlying pressure, the actual stress state of the deep-thickness coverage soil body in the natural environment cannot be accurately simulated, and the infiltration erosion evolution rule of the soil body under the deep-thickness stress condition is difficult to truly reflect; thirdly, the sample top cover of a part of test device is sealed by adopting a traditional rubber strip, the deformation of the sample box is easy to cause sealing failure under ultrahigh pressure, and the progressive development process of the concentrated dominant leakage channel in the sample can not be observed, so that the treatment effect on sidewall seepage and dominant seepage is poor. Chinese patent CN110907329A discloses a large scale corrosion test system and a test method thereof, and although the hydraulic gradient can be regulated by adjusting the height of a water tank, the problems of sealing failure, incapability of observing the development of internal seepage, and poor side wall seepage and dominant seepage treatment still exist. Therefore, an ultra-large vertical compression horizontal seepage erosion experimental device capable of solving the defects of the existing device is developed, and the experimental device has important engineering practical value and theoretical research significance. Disclosure of Invention The invention aims to overcome the defects of the existing seepage corrosion test device, provides an ultra-large vertical compression horizontal seepage corrosion test box device and a test method, realizes self-adaptive sealing after deformation of a test box under ultra-high pressure, effectively inhibits side wall seepage and dominant seepage, can more accurately and intuitively sense and visualize the progressive development process of seepage corrosion in a soil body, simulates the actual stress state of the soil body of a deep covering layer, and avoids the influence of size effect on test results. In order to achieve the above purpose, one of the technical schemes adopted by the invention is as follows: The ultra-large vertical compression horizontal seepage erosion experiment box device is characterized in that the main body of the device is a high-strength experiment box body, the high-strength experiment box body is of a steel structure with the maximum vertical load of 10MPa, a sample bin used for placing detection samples is arranged in the high-strength experiment box body, the internal size of the sample bin is 1000mm multiplied by 1000mm, one side of the sample bin is provided with an upstream water inlet bin, the other side of the sample bin is provided with a downstream water outlet bin, the upstream water inlet bin is provided with a water inlet, the downstream water outlet bin is provided with a water outlet funnel used for collecting fine particle soil samples, the top of the sample bin is provided with a top cover, an adaptive sealing structure used for inhibiting dominant seepage from occurring is arranged between the top cover and the box body, a plurality of wireless miniature pressure sensors are arranged in an array and used for monitoring pore water pressure space-time changes of different positions inside a soil body, perception and visualization of a progressive seepage force