Deep Underground Science and Engineering最新文献_第2页

Development of an optimization model for a monitoring point in tunnel stress deduction using a machine learning algorithm 利用机器学习算法开发隧道应力推导监测点优化模型

Deep Underground Science and Engineering Pub Date : 2024-03-03 DOI: 10.1002/dug2.12076

X. Tan, Weizhong Chen, Lu-yu Wang, Wei Ye

{"title":"Development of an optimization model for a monitoring point in tunnel stress deduction using a machine learning algorithm","authors":"X. Tan, Weizhong Chen, Lu-yu Wang, Wei Ye","doi":"10.1002/dug2.12076","DOIUrl":"https://doi.org/10.1002/dug2.12076","url":null,"abstract":"Monitoring of the mechanical behavior of underwater shield tunnels is vital for ensuring their long‐term structural stability. Typically determined by empirical or semi‐empirical methods, the limited number of monitoring points and coarse monitoring schemes pose huge challenges in terms of capturing the complete mechanical state of the entire structure. Therefore, with the aim of optimizing the monitoring scheme, this study introduces a spatial deduction model for the stress distribution of the overall structure using a machine learning algorithm. Initially, clustering experiments were performed on a numerical data set to determine the typical positions of structural mechanical responses. Subsequently, supervised learning methods were applied to derive the data information across the entire surface by using the data from these typical positions, which allows flexibility in the number and combinations of these points. According to the evaluation results of the model under various conditions, the optimized number of monitoring points and their locations are determined. Experimental findings suggest that an excessive number of monitoring points results in information redundancy, thus diminishing the deduction capability. The primary positions for monitoring points are determined as the spandrel and hance of the tunnel structure, with the arch crown and inch arch serving as additional positions to enhance the monitoring network. Compared with common methods, the proposed model shows significantly improved characterization abilities, establishing its reliability for optimizing the monitoring scheme.","PeriodicalId":505870,"journal":{"name":"Deep Underground Science and Engineering","volume":"8 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140267177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Experimental study on the influence of content and fineness of fly ash on the mechanical properties of grouting slurries 粉煤灰含量和细度对灌浆泥浆机械性能影响的实验研究

Deep Underground Science and Engineering Pub Date : 2024-02-26 DOI: 10.1002/dug2.12070

Hua Jiang, Handong Zhang, Xiaoyan Zhang, Jinxun Zhang, Yusheng Jiang

{"title":"Experimental study on the influence of content and fineness of fly ash on the mechanical properties of grouting slurries","authors":"Hua Jiang, Handong Zhang, Xiaoyan Zhang, Jinxun Zhang, Yusheng Jiang","doi":"10.1002/dug2.12070","DOIUrl":"https://doi.org/10.1002/dug2.12070","url":null,"abstract":"Excavation gaps around the front shield can be generated during shield construction, resulting in significant ground settlement. Traditional synchronous grouting slurries are unsuitable for filling these gaps during tunneling under existing subway lines. To address this issue, experiments are conducted on mix characteristics and hardening properties of slurries with variations in fineness and contents of fly ash. The experimental and computed tomography scan results yield the following findings: (1) fly ash with high fineness can effectively reduce the early strength of slurries and enhance their injectability. This improves the filling effect on micropores in the slurry and ultimately enhances the final hardening strength. (2) Fineness of fly ash controls the process of slurry hydration. The higher the fineness of fly ash, the more visible the exothermic hydration of slurry and the earlier the highest temperature peak appears. (3) Fly ash with high fineness can effectively increase the density and consolidation rate of slurries, resulting in greater improvement in slurry strength, particularly when the ratio of fly ash to cement (mf/mc) is 0.75. (4) Fly ash with high fineness can effectively decrease the likelihood of appearance of pores in the slurry, optimize the pore structure, and enhance the strength of slurries after consolidation.","PeriodicalId":505870,"journal":{"name":"Deep Underground Science and Engineering","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140430530","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A meso‐damage‐based constitutive model for yellow sandstone under dry–wet cycles 干湿循环条件下基于中观损伤的黄砂岩构成模型

Deep Underground Science and Engineering Pub Date : 2024-02-25 DOI: 10.1002/dug2.12071

Zhe Qin, Runchang Zhang, Weizheng Mao, Jihuan Han, Zhiwen Li, Sunhao Zhang

{"title":"A meso‐damage‐based constitutive model for yellow sandstone under dry–wet cycles","authors":"Zhe Qin, Runchang Zhang, Weizheng Mao, Jihuan Han, Zhiwen Li, Sunhao Zhang","doi":"10.1002/dug2.12071","DOIUrl":"https://doi.org/10.1002/dug2.12071","url":null,"abstract":"The mechanical properties of rocks weaken under dry–wet cycles. This weakening may significantly modify the safety reserve of underground caverns or reservoir bank slopes. However, meso‐damage has not been carefully studied based on micromechanical observations and analyses. Therefore, in this study, meso‐damage of a yellow sandstone is investigated and a meso‐damage‐based constitutive model for dry–wet cycles is proposed. First, computed tomography scanning and uniaxial compression tests were conducted on yellow sandstones under different dry–wet cycles. Second, the evolution of rock mesostructures and the damage mechanism subjected to dry–wet cycles were simulated using the discrete element method with Particle Flow Code in 2 Dimensions (PFC2D) software. Third, a constitutive model was proposed based on the meso‐statistical theory and damage mechanics. Finally, this constitutive model was verified with the experimental results to check its prediction capability. It is found that the radius and number of pore throats in the sandstone increase gradually with the number of dry–wet cycles, and the pore structure connectivity is also improved. The contact force of sandstone interparticle cementation decreases approximately linearly and the continuity of the particle contact network is continuously broken. The meso‐deformation and strength parameters show similar declining patterns to the modulus of elasticity and peak strength of the rock sample, respectively. This meso‐damage‐based constitutive model can describe well the rock deformation in the initial pressure density stage and the damage stage under the coupling effect of dry–wet cycles and loads.","PeriodicalId":505870,"journal":{"name":"Deep Underground Science and Engineering","volume":"29 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140432071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Effects of elevated ground temperatures on properties of cement grouts for deep rock grouting 地温升高对用于深层岩石灌浆的水泥灌浆料性能的影响

Deep Underground Science and Engineering Pub Date : 2024-02-04 DOI: 10.1002/dug2.12073

Zhipeng Xu, Jianping Sun, Runguo Li, Lei He, Changwu Liu

{"title":"Effects of elevated ground temperatures on properties of cement grouts for deep rock grouting","authors":"Zhipeng Xu, Jianping Sun, Runguo Li, Lei He, Changwu Liu","doi":"10.1002/dug2.12073","DOIUrl":"https://doi.org/10.1002/dug2.12073","url":null,"abstract":"Appropriate determination of the mix ratios of cement grouts is of vital importance to the quality of rock grouting and the risk reduction of groundwater inflow. The behavior of grout, often highly temperature dependent, is likely to be affected by the elevated ground temperature in deep rock masses. This paper aims to experimentally gain insights into the effects of elevated ground temperatures on the properties of cement grout in fresh and hardened states in deep rock grouting. The results revealed that a temperature of 35°C is crucial for changes in the properties of thick cement grout with a water–cement ratio of less than 0.8. When the temperature is up to 35°C, there can be significant improvements in rheological parameters, acceleration of grout setting, and increase in the rheological time dependence of thick cement grout; however, there may also be a slight impact on the initial grout flowability and the nature of shear thinning. The high temperature may still improve the stability of fresh cement grout and also improve the porosity and creep deformation of hardened cement grout considerably. The proposed constitutive model that couples the Burgers model with a fractional derivative‐based Abel dashpot in the series can be used to characterize the creep behavior of hardened cement grout appropriately. The paper provides a valuable reference for optimization of mixture design of cement grouts, thus enhancing deep rock grouting quality and improving safety.","PeriodicalId":505870,"journal":{"name":"Deep Underground Science and Engineering","volume":"565 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139806786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Effects of elevated ground temperatures on properties of cement grouts for deep rock grouting 地温升高对用于深层岩石灌浆的水泥灌浆料性能的影响

Deep Underground Science and Engineering Pub Date : 2024-02-04 DOI: 10.1002/dug2.12073

Zhipeng Xu, Jianping Sun, Runguo Li, Lei He, Changwu Liu

{"title":"Effects of elevated ground temperatures on properties of cement grouts for deep rock grouting","authors":"Zhipeng Xu, Jianping Sun, Runguo Li, Lei He, Changwu Liu","doi":"10.1002/dug2.12073","DOIUrl":"https://doi.org/10.1002/dug2.12073","url":null,"abstract":"Appropriate determination of the mix ratios of cement grouts is of vital importance to the quality of rock grouting and the risk reduction of groundwater inflow. The behavior of grout, often highly temperature dependent, is likely to be affected by the elevated ground temperature in deep rock masses. This paper aims to experimentally gain insights into the effects of elevated ground temperatures on the properties of cement grout in fresh and hardened states in deep rock grouting. The results revealed that a temperature of 35°C is crucial for changes in the properties of thick cement grout with a water–cement ratio of less than 0.8. When the temperature is up to 35°C, there can be significant improvements in rheological parameters, acceleration of grout setting, and increase in the rheological time dependence of thick cement grout; however, there may also be a slight impact on the initial grout flowability and the nature of shear thinning. The high temperature may still improve the stability of fresh cement grout and also improve the porosity and creep deformation of hardened cement grout considerably. The proposed constitutive model that couples the Burgers model with a fractional derivative‐based Abel dashpot in the series can be used to characterize the creep behavior of hardened cement grout appropriately. The paper provides a valuable reference for optimization of mixture design of cement grouts, thus enhancing deep rock grouting quality and improving safety.","PeriodicalId":505870,"journal":{"name":"Deep Underground Science and Engineering","volume":"10 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139866473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Flow field analysis and particle erosion of tunnel‐slope systems under coupling between runoff and fast (slow) seepage 径流与快（慢）渗流耦合条件下隧道斜坡系统的流场分析与颗粒侵蚀

Deep Underground Science and Engineering Pub Date : 2023-12-19 DOI: 10.1002/dug2.12062

Shuai Zhang, Danqing Song, Ruiliang Zhang, Kai Zhang, Qi Zhao, Suraksha Sharma

{"title":"Flow field analysis and particle erosion of tunnel‐slope systems under coupling between runoff and fast (slow) seepage","authors":"Shuai Zhang, Danqing Song, Ruiliang Zhang, Kai Zhang, Qi Zhao, Suraksha Sharma","doi":"10.1002/dug2.12062","DOIUrl":"https://doi.org/10.1002/dug2.12062","url":null,"abstract":"The presence of particles on the surface of a tunnel slope renders it susceptible to erosion by water flow, which is a major cause of soil and water loss. In this study, a nonlinear mathematical model and a mechanical equilibrium model are developed to investigate the distribution of flow fields and particle motion characteristics of tunnel slopes, respectively. The mathematical model of flow fields comprises three parts: a runoff region, a highly permeable soil layer, and a weakly permeable soil layer. The Navier‒Stokes equation controls fluid motion in the runoff region, while the Brinkman‐extended Darcy equation governs fast and slow seepage in the highly and weakly permeable soil layers, respectively. Analytical solutions are derived for the velocity profile and shear stress expression of the model flow field under the boundary condition of continuous transition of velocity and stress at the fluid‒solid interface. The shear stress distribution shows that the shear stress at the tunnel‐slope surface is the largest, followed by the shear stress of the soil interface, indicating that particles in these two locations are most vulnerable to erosion. A mechanical equilibrium model of sliding and rolling of single particles is established at the fluid‒solid interface, and the safety factor of particle motion (sliding and rolling) is derived. Sensitivity analysis shows that by increasing the runoff depth, slope angle, and soil permeability, the erosion of soil particles will be aggravated on the tunnel‐slope surface, but by increasing the particle diameter, particle‐specific gravity, and particle stacking angle, the erosion resistance ability of the tunnel‐slope surface particles will be enhanced. This study can serve as a reference for the analysis of surface soil and water loss in tunnel‐slope systems.","PeriodicalId":505870,"journal":{"name":"Deep Underground Science and Engineering","volume":"29 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139172422","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0