CN-121540572-B - Triaxial test method for simulating cyclic accumulated deformation of dam-building rock-fill material under reciprocating water storage effect

CN121540572BCN 121540572 BCN121540572 BCN 121540572BCN-121540572-B

Abstract

A triaxial test method for simulating cyclic accumulation deformation of a rockfill material for a dam under the action of reciprocating water storage belongs to the technical field of cyclic triaxial test methods, and comprises the steps of firstly, carrying out a rheological test under a full storage-state stress state, secondly, continuously carrying out a triaxial cyclic test under the action of water cyclic load after the rheological test is finished, thirdly, repeating the first two steps to determine a frequency threshold, fourthly, carrying out the rheological test under the condition that full storage falls back to the lowest stress state of a water level, fifth, carrying out the triaxial cyclic test under the consolidation standard, and sixthly, removing the rheological deformation to obtain cyclic accumulation deformation of the rockfill material under the action of water cyclic load. The invention provides a test consolidation standard, a loading frequency threshold value and a rheological deformation separation method, which can obviously reduce test deviation caused by a rate effect and a rheological effect, improve the accuracy of long-term deformation simulation of piled stones, shorten test time consumption and greatly improve test efficiency.

Inventors

ZOU DEGAO
Han Musen
LIU JINGMAO
ZHANG DAN
WANG XIAODONG
NING FANWEI
WANG XIAOAN
ZHOU CHENGUANG
CHEN JIAQI

Assignees

大连理工大学
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: 20260122

Claims (9)

1. The triaxial test method for simulating the cyclic accumulated deformation of the rockfill material of the dam under the action of reciprocating water storage is characterized by comprising the following steps of: Step S1, carrying out a rheological test under full storage-state stress state by using a sample 1, determining the stress state of the heap and stones when the reservoir water level is full storage, and carrying out a triaxial rheological test under full storage-state stress state of the heap and stones to obtain a rheological deformation value of the sample 1; step S2, after the triaxial rheological test of the step S1 is finished, continuing to use the sample 1 to develop a triaxial circulation test under the action of water circulation load to obtain a circulating accumulated deformation value of the sample 1; Step S3, repeating the processes of the step S1 and the step S2 to obtain two samples capable of determining the frequency threshold value, and finally determining the frequency threshold value, wherein the steps are as follows: Step S31, when the triaxial rheological test in the step S1 is repeated by using the sample 2, developing the triaxial rheological test in a stress state of the heap and the rock material in a full storage state to obtain a rheological deformation value of the sample 2; Step S32, continuously using the sample 2, and obtaining a cyclic accumulated deformation value of the sample 2 when the triaxial cyclic test in the step S2 is repeated; Step S33, repeating the steps S1 and S2, and sequentially sorting the sample names according to sample 1, sample 2, sample 3, & gt, and sample N, specifically: In the step S1, a triaxial rheological test is carried out in a stress state when a sample 3 full storage is in a state, so as to obtain a rheological deformation value of the sample 3; In the step S2, a triaxial cyclic test is carried out by using the sample 3, and the loading frequency is reduced by ten times every time the triaxial cyclic test is repeated, and the like until the difference between the cyclic cumulative deformation values of two adjacent samples is less than 0.03% after the cyclic loading is carried out for 100 times between the adjacent two different loading frequencies; Step S34, after the difference between the cyclic accumulated deformation values of two adjacent samples in the step S33 is less than 0.03%, taking the larger of the two loading frequencies as a frequency threshold; Step S4, defining the samples with the determined frequency threshold as new samples, namely a new sample 1 and a new sample 2 respectively, taking the new sample 1, carrying out a triaxial rheological test under the lowest stress state from full storage to the water level, determining the stress state of the heap rock when the water level of the reservoir is from full storage to the lowest water level, carrying out the triaxial rheological test under the stress state of the heap rock when the water level of the reservoir is from full storage to the lowest water level, and obtaining the rheological deformation value of the new sample 1; step S5, taking a new sample 2 to carry out a triaxial circulation test under a consolidation standard, and carrying out the triaxial circulation test by taking the frequency threshold in the step S3 as a loading frequency to obtain a circulation accumulated deformation value of the new sample 2; s6, eliminating the rheological deformation value to obtain the cyclic accumulated deformation of the rock-fill material under the action of the water cyclic load; According to the rheological deformation value of the sample 1 in the step S1 and the rheological deformation value of the new sample 1 in the step S4, converting time into cyclic loading times to obtain data of the rheological deformation value and the cyclic loading times, obtaining the rheological deformation value to be removed based on the rheological deformation value of the sample 1 in the full storage state and the rheological deformation value of the new sample 1 when the rheological deformation value falls from full storage to the lowest water level, and finally subtracting the rheological deformation value to be removed from the cyclic accumulated deformation value of the new sample 2 in the step S5 to obtain cyclic accumulated deformation.
2. The triaxial test method for simulating the cyclic cumulative deformation of the rockfill material for dam building under the action of reciprocating water storage according to claim 1, wherein in the step S1, stress states comprise confining pressure and bias stress, and when the triaxial rheological test is carried out, the triaxial rheological test ending standard is that the axial deformation rate is less than 0.01%/12 h.
3. The triaxial test method for simulating cyclic cumulative deformation of a rockfill material for dam building under a reciprocating water storage effect according to claim 1, wherein in the triaxial cyclic test in the step S2, the loading frequency 1 is selected to be 0.1Hz, and the cyclic loading times are not less than 100 times.
4. The triaxial test method for simulating cyclic cumulative deformation of rockfill material for dam construction under the action of reciprocating water storage according to claim 1, wherein in the triaxial cyclic test in the step S33, the first repetition loading frequency 2 is 0.01Hz, the second repetition loading frequency 3 is 0.001Hz, the third repetition loading frequency 4 is 0.0001Hz, and so on.
5. The triaxial test method for simulating cyclic cumulative deformation of a rockfill material for dam construction under a reciprocating water storage effect according to claim 4, wherein in the step S32, the loading frequency is selected to be 0.01Hz, and the cyclic loading times are not less than 100 times.
6. The triaxial test method for simulating cyclic cumulative deformation of rockfill material for dam construction under a reciprocating water storage action according to claim 4, wherein in the step S33, a new sample is used each time the steps S1 and S2 are repeated.
7. The triaxial test method for simulating cyclic cumulative deformation of a rockfill material for dam building under a reciprocating water storage effect according to claim 1, wherein in the triaxial rheological test in the step S4, the axial deformation rate is less than 0.01%/12h as a triaxial rheological test ending standard.
8. The triaxial test method for simulating cyclic cumulative deformation of rockfill material for dam construction under the action of reciprocating water storage according to claim 1, wherein in the triaxial cyclic test in the step S5, the axial deformation rate is less than 0.01%/0.5h as the consolidation standard.
9. The triaxial test method for simulating cyclic cumulative deformation of a rockfill material for dam building under a reciprocating water storage effect according to claim 1, wherein in step S6, specifically: Converting time into cyclic loading times through a formula (1) to obtain rheological deformation value and cyclic loading times data by using the rheological deformation value of the triaxial rheological test of the sample 1 in the step S1 in full storage state and the rheological deformation value obtained by the triaxial rheological test of the new sample 1 in the step S4 when full storage falls back to the lowest water level; T=1/f (1) wherein T is the time for which the rheological test is performed, and f is the loading frequency; Processing the rheological deformation value of the triaxial rheological test sample 1 in full storage state and the rheological deformation value of the new sample 1 when full storage falls to the lowest water level according to a formula (2) to obtain a rheological deformation value epsilon cre to be removed; ε cre =（ε cre, Full storage A +ε cre, Dead water level )/2 (2) Wherein ε cre is the deformation of the fluid to be removed, ε cre, Full storage A is the deformation of full storage, ε cre, Dead water level is the deformation of fluid from full storage to the lowest water level.

Description

Triaxial test method for simulating cyclic accumulated deformation of dam-building rock-fill material under reciprocating water storage effect Technical Field The invention belongs to the technical field of circulating triaxial test methods, and relates to a triaxial test method for simulating circulating accumulated deformation of a dam-building rock-fill material under the action of reciprocating water storage. Background At present, the hydroelectric engineering is used as a core support of a novel energy system, and has wide development prospect. The rock-fill dam has become the core dam of pumped storage power stations and hydraulic junction engineering by virtue of the advantages of strong adaptability of the dam building materials, high construction efficiency and remarkable economy, and a plurality of rock-fill dam projects with leading technical level in the world have been built in China. However, the problem of long-term deformation of the rock-fill dam is always a core concern in engineering design, construction and operation, and long-term deformation easily causes diseases such as extrusion damage of an impermeable body, water stop failure of a joint and the like, and seriously threatens the durability and the overall operation safety of an impermeable system of the dam. The prior study shows that the reciprocating water storage is one of the key factors influencing the long-term deformation of the rock-fill dam. Compared with the conventional hydraulic junction engineering, the pumped storage power station has higher water level circulation frequency and larger amplitude due to the operation requirement of pumping energy storage-draining power generation, and the annual amplitude of the water level is quite remarkable even in the conventional hydraulic junction engineering. The long-term monitoring data show that the deformation of the dam body presents continuous accumulation characteristics along with the periodic fluctuation of the water level of the reservoir, but the deformation mechanism and accumulation rule of the dam body are not fully revealed. Although the influence of water circulation load on the long-term deformation of the rock-fill dam is primarily known, the related indoor experimental simulation and mechanism research still face serious challenges, and the core difficulty is that the water circulation load and the earthquake load have great differences in loading frequency. The existing research on the cyclic deformation test of the stacking material focuses on the earthquake load, the water cyclic load belongs to the low-frequency and long-period load, and the frequency difference between the two loads can reach 10 4 orders of magnitude. The large difference in loading frequency may cause cyclic cumulative deformations of the heap in the laboratory test to be affected by rheological and rate effects. At present, as a core means for researching the mechanical properties of the rock-fill material, the indoor triaxial test is still difficult to effectively simulate the low-frequency and long-period characteristics of the water circulation load, on one hand, the existing test mostly adopts a test scheme suitable for high-frequency load, and the influence of a specific effect under low-frequency load is not fully considered, so that the deviation between a test result and an actual engineering deformation rule is larger; on the other hand, the low-frequency and long-period test requirement puts higher requirements on stability, test precision and test period control of test equipment, and the deep development of related researches is limited. Although the related patent of the prior disclosed triaxial test realizes technical breakthrough in a specific scene, the technical blank cannot be filled by designing a test scheme aiming at low-frequency long-period water circulation load caused by reciprocating water storage, for example, the China patent application No. CN202311071434.6 provides a triaxial test system and a triaxial test method for saturated or unsaturated circulation under the freeze thawing action, the mechanical property influence of the focused freeze thawing circulation on saturated/unsaturated soil is focused, and the core is that the temperature change is simulated through a constant-temperature cold bath bin and a frost heaving bin, the low-frequency characteristic of the water circulation load is not involved, and the interference of the rate effect and the rheological effect on the circulating accumulated deformation of piled stones is not considered. The Chinese patent (application number CN 201810604040.5) provides an all-in-one machine suitable for a mudstone dry-wet cycle test and a triaxial test, and realizes the integration of the mudstone dry-wet cycle test and the triaxial test, and introduces CT scanning to monitor crack development, but the test object is the mudstone, the loading condition is designed around 'dry-wet alternation', the control standa