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"Water damage"
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Progressive Failure Analysis of Slope Water Damage Based on Improved Green-Ampt Infiltration Model
In order to get the law of rainwater infiltration and the law of progressive water damage, the slope of Tianshang bridge foundation in Yunnan Province of China is taken as the engineering basis. The site investigation of the damaged slope is carried out. The traditional Green-Ampt model is improved by considering the ponding effect of dynamic water flow on the slope surface. Based on the variation characteristics of wetting front obtained by the improved infiltration model, the progressive failure process of slope with continuous infiltration is simulated by FLAC3D software. The results show that the water damage of Tianshang bridge slope is mainly caused by the slope absorbing a lot of rainwater in a short time, which has obvious time discontinuity characteristics in time, and shows obvious multi-layer progressive failure characteristics in failure space. The wetting front characteristics obtained by the improved Green-Ampt infiltration model are more consistent with the engineering practice. The water accumulation effect of surface water gradually weakens with the increase of the wet front depth. The slope failure develops gradually from the toe to the top and from shallow to deep. The intermittent failure characteristics provide surplus time for the engineering treatment, the gravel soil slope should be treated after a small-scale water damage occurs.
Journal Article
Mapping of the susceptibility of China‒Russia crude oil pipelines to water damage in permafrost regions in Northeast China
In permafrost regions, climate warming and extreme precipitation events, combined with rugged local terrains, pose considerable threats of water damage to buried crude oil pipelines. However, the susceptibility to water damage in these areas has received limited attention and research. Aiming to evaluate the susceptibility to water damage (STWD) of the China‒Russia Crude Oil Pipelines (CRCOPs) I and II, random forest (RF) algorithms, correlation analysis of influencing factors and on-site surveys were employed. The assessment, based on RF algorithms, field survey data from 2019 to 2022 and 14 geographically related factors, reveals that approximately 14.5% of the study area demonstrates high STWD, indicating a generally low risk of STWD across most segments of the CRCOPs. The pipeline segments between Wu’erqi–Jagdaqi and Jingsong–Xinlin display the highest STWD. Areas with high STWD typically experience ample precipitation, flow accumulation in flat, low-lying terrains, low surface roughness, over unconsolidated deposits and warm (>−1 °C) Xing’an (hemiboreal) permafrost and proximity to rivers. This study not only enhances theoretical understanding of mitigating water damage to pipeline foundations in cold regions but also offers important technical insights for the sustainable operation of these lifeline infrastructures. Future research should focus on continuous monitoring of pipeline foundation soil safety, improving numerical models for pipeline river crossing evaluations and refining water damage risks assessment through deep learning-based models.
Journal Article
Laboratory Investigation of the Water Damage Resistance of Tuff Asphalt Mixture Modified with Additives
To improve the water damage resistance performance of a tuff asphalt mixture, a tuff mixture with cement and a liquid anti-stripping agent was used as the research object, and limestone and tuff mixtures without additives were selected as contrast samples. Through an improved boiling test and a water stability test before and after aging, the modification effect of the tuff mixture with additives of different types and contents on water damage resistance was evaluated to obtain the appropriate type and content of additives. On this basis, the other road performance measures of the selected mixture were further evaluated by immersion rutting and beam bending tests to verify the modification effect of the additive on the tuff mixture. Results showed that adding the appropriate cement content to the tuff mixture provided excellent resistance to the water damage effect. An optimal content of 2% cement additive in the mixture was obtained, and its high-temperature anti-rutting and low-temperature bending performance were also verified. Adhesion between tuff aggregates and asphalt polymer under water conditions was significantly improved and close to that of limestone aggregates. The modification effect of water stability after mixture aging was better than that of the anti-stripping agent. The residual stability and freeze–thaw splitting strength ratio of 2% cement content mixture were increased by about 21.5% and 16.7%, respectively, compared with those of the tuff mixture control.
Journal Article
Water Damage Resistance of Tuff Asphalt Mixtures with Admixtures Based on Surface Energy Theory
At present, tuff aggregates as asphalt pavement mixtures have insufficient water damage resistance; hence, modifying and evaluating the related properties of tuff asphalt mixtures are necessary. In this study, cement and a liquid antistripping agent were selected as admixtures, and tuff and limestone mixtures without admixtures were selected as control. The surface energy for the SBS-modified asphalt polymers and aggregates in the mixtures was evaluated by using surface energy theory. The adhesion work and the spalling work of the polymer–aggregate interface was calculated, and a factor k was proposed to predict the water damage resistance of the tuff mixture with admixtures. The prediction values were compared with those of the macroscopic water stability test for the mixture. The results of this research showed that the factor k after adding admixtures was improved, and the increase range was from 7.14% to 47.62%. The admixture scheme with the best improvement was that with 2% cement content, in which the k value increased by 21.57% and 47.62% compared with that of the limestone and tuff mixtures without admixtures, respectively. The tested water stability indexes and the predicted factor k under different admixture schemes exhibited a good positive correlation, and the correlation equations were obtained by linear fitting. Thus, it was feasible to use the factor k characterizing the water damage resistance of tuff mixtures using surface energy theory.
Journal Article
Simulation analysis of water resource damage feature and development degree of mining-induced fracture at ecologically fragile mining area
Mining-induced water damage has become one of wide concerned issues in contemporary society. Knowing the main causes to water resource damage (especially the superficial aquifer damage) as well as the damage mode is the basis for realizing water conservation. In this paper, the mining height and position of aquifuge are regarded as the main influencing factors in analyzing the change of aquifer. Taking the geological conditions of Yili No. 4 coal mine as an example, a total of 18 numerical analysis models with different mining heights (3, 5, 8, 10, 15, 20 m) and different positions of aquifuge (upper, middle and bottom) as changing conditions were established using universal distinct element code discrete element simulation software. The variation characteristics of water resources in aquifers after disturbance were studied. The variation of water pressure with mining height and position of aquifuge was analyzed. The variation of water pressure in aquifer was proposed as a novel criterion for distinguishing the development degree of mining-induced fracture. The criterion for determining the failure of aquifer was established based on the ratio of water pressure change and mining height (P/H), which is a pioneering research on the relationship between mining-induced fracture and aquifer failure. This study provides a reference for evaluating the development degree of mining-induced fracture and provides theoretical basis for analyzing the coupling relationship between mining and water resource change in aquifer and for water conservation at ecologically fragile mining area.
Journal Article
Analysis of the Interfacial Interaction between Wood Tar-Rejuvenated Asphalt and Aggregate Based on Molecular Dynamics Simulation
This study utilized molecular dynamics simulation to investigate the adhesion process between wood tar-rejuvenated asphalt and acid/alkaline aggregate. Initially, various indicators including the contact area, cohesion coefficient, and interaction energy were employed to assess the adhesion effect under dry conditions. This revealed the action mechanism of the wood tar-rejuvenator in enhancing the adhesion performance between aged asphalt and aggregate. Subsequently, an asphalt–water–aggregate interface model was developed to simulate the water damage process of the asphalt mixture. This aimed to unveil the damage mechanism of water intrusion on the adhesion performance of the asphalt–aggregate interface and evaluate the water damage resistance of wood tar-rejuvenated asphalt through adhesion energy, stripping work, and the energy ratio. The findings indicate that wood tar-rejuvenated asphalt exhibits favorable adhesion properties with both acid and alkaline aggregates. The addition of wood tar-rejuvenated asphalt increased the interaction energy between aged asphalt and acid and alkali aggregates by 67.75 kJ/mol and 97.3 kJ/mol, respectively. The addition of a wood tar rejuvenator enhances the interaction energy between aged asphalt and aggregate, thereby increasing mutual attraction and enlarging the contact area. The adhesion between asphalt and aggregates hinges on the interaction between asphaltene and aggregates, and the wood tar rejuvenator reduces the diffusion ability of asphaltene in the attractive state of the aggregate, resulting in stable aggregation. Moisture intrusion increased the aggregation distance between asphaltene and aggregate by 14.1% and decreased the degree of aggregation by 24.0%, thereby reducing the interaction energy. The extent of damage caused by water intrusion is linked to the aggregation distance, with greater distances leading to deeper damage. Under wet conditions, the interaction energy of wood tar-rejuvenated asphalt increased by 78.2% in the acidic aggregate system and 98.1% in the basic aggregate system compared with aged asphalt. Meanwhile, wood tar-based rejuvenated asphalt improves the adhesion between aged asphalt and aggregate and reduces the stripping function of asphalt affected by water replacement, which results in the ER value of wood tar-rejuvenated asphalt being higher than that of the original asphalt by 0.12 and 0.22 in the acidic and alkaline environments, respectively, thus showing excellent resistance to water damage. This study provides new criteria for the selection of rejuvenators for waste asphalt, which will help in the future selection of superior rejuvenators for aged asphalt and reduce the possibility of choosing the wrong rejuvenator.
Journal Article
Study on the Performance Improvement of Straw Fiber Modified Asphalt by Vegetable Oil
As a plasticizer, vegetable oil can improve the compatibility between straw fibers and an asphalt matrix and promote the uniform dispersion of fibers, thereby improving the viscoelastic properties of the composite material. This paper selected three vegetable oils: tall oil, rapeseed oil, and palm wax. Through dynamic shear rheology tests, low-temperature bending beam rheology tests, contact angle tests, and infrared spectroscopy tests, the vegetable-oil-reinforced straw fiber modification was analyzed from different points of view. The research results show that palm wax significantly improves the high-temperature rheological properties of straw-fiber-modified asphalt but has a negative impact on low-temperature properties. Tall oil can most significantly improve the low-temperature rheological properties of straw-fiber-modified asphalt. Rapeseed oil has the most obvious effect in improving the adhesion and water damage resistance of straw-fiber-modified asphalt. In addition, the research shows that all three vegetable oils exist in the modified asphalt in adsorbed form, and no new compounds are generated. These research results provide theoretical guidance value for the application of straw-fiber-modified asphalt pavement in different environments.
Journal Article
Moisture Sensitivity Evaluation of the Asphalt Mortar-Aggregate Filler Interface Using Pull-Out Testing and 3-D Structural Imaging
Moisture damage is one of the undesired distresses occurring in flexible asphalt pavements, mostly through water intrusion that weakens and ultimately degrades the asphalt mortar-aggregate interfacial bond. One method to mitigate this distress is using anti-stripping or anti-spalling filler materials that, however, require a systematic quantification of their interfacial bonding potential and moisture tolerance properties prior to wide-scale field use. With this background, this study was conducted to comparatively evaluate and quantitatively characterize the moisture sensitivity and water damage resistance of the interfacial bonding between the asphalt mortar and aggregate fillers. Using an in-house custom developed water-temperature coupling setup, numerous laboratory pull-out tests were carried out on the asphalt mortar with four different filler materials, namely limestone mineral powder, cement, slaked (hydrated) lime, and waste brake pad powder, respectively. In the study, the effects of moisture wet-curing conditions, temperature, and filler types were comparatively evaluated to quantify the water damage resistance of the asphalt mortar-aggregate filler interface. For interfacial microscopic characterization, the Image-Pro Plus software, 3-D digital imaging, and scanning electron microscope (SEM) were jointly used to measure the spalling rate and the surface micromorphology of the asphalt mortar and aggregate filler before and after water saturation, respectively. In general, the pull-out tensile force exhibited a decreasing response trend with more water damage and interfacial bonding decay as the moisture wet-curing temperature and time were increased. Overall, the results indicated superiority for slaked (hydrated) lime over the other filler materials with respect to enhancing and optimizing the asphalt mortar-aggregate interfacial bonding strength, moisture tolerance, and water damage resistance, respectively—with limestone mineral powder being the poorest performer.
Journal Article
Experimental Investigation of Reservoir Fluid Interlayer Crossflow Through Fracture During the Drainage Stage of Coal Measure Gas Well
Coal measure gas (CMG) development is effective to increase gas production of coalbed methane wells. However, the reservoir fluid migration law during CMG development is different from that of single-layer development and it remains to be identified. In this work, self-developed devices were used to study fluid interlayer crossflow (IC) law through fractures in the single-phase liquid flow and gas–liquid two-phase flow stages during CMG well drainage. The results showed that, in the single-phase flow stage, liquid flowed from the medium- and low-permeability samples to the high-permeability sample, changing the fluid pressure and flow rate of each sample, and promoting total liquid production. In the two-phase flow stage, the gas IC caused total gas production capacity to increase, but the liquid IC was inhibited, which made the liquid production capacity to increase firstly and then decrease. Also, the irreducible liquid saturation of the medium- and low-permeability samples increased, aggravating the water blocking damage. However, by adding the surfactant AN, the liquid surface tension and pore capillary pressure were decreased, and the irreducible liquid saturation of each sample before and after the fluid IC was reduced. Thus, the water blocking damage of each sample was mitigated, including the damage aggravated by the fluid IC, promoting the desorption and migration of coalbed methane, as well as the CMG efficient development. This study is helpful to clarify the CMG migration law, and provides fundamental supports for the optimization of CMG development technology.
Journal Article