\r郑 刚¹，哈 达¹，程雪松¹，曾超峰²，曹剑然\r¹\r
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AuthorsHTML:\r郑 刚¹，哈 达¹，程雪松¹，曾超峰²，曹剑然\r¹\r
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AuthorsListE:\rZheng Gang¹，Ha Da¹，Cheng Xuesong¹，Zeng Chaofeng²，Cao Jianran\r¹\r
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AuthorsHTMLE:\rZheng Gang¹，Ha Da¹，Cheng Xuesong¹，Zeng Chaofeng²，Cao Jianran\r¹\r
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Unit:\r1. 滨海土木工程结构与安全教育部重点实验室(天津大学)，天津 300354；
2. 湖南科技大学岩土工程稳定控制与健康监测湖南省重点实验室，湘潭 411201\r
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Unit_EngLish:\r1. Key Laboratory of Coast Civil Structure Safety of Ministry of Education(Tianjin University)，Tianjin 300354，China；
2. Hunan Provincial Key Laboratory of Geotechnical Engineering for Stability Control and Health Monitoring，Hunan University of Science and Technology，Xiangtan 411201，China\r
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Abstract_Chinese:\r\r在天津、上海等沿海地区基坑工程中，由于地下水位较高且含水层分布广泛，当基坑抗突涌稳定安全系数不足时，需对承压含水层减压抽水．根据有效应力原则，减压抽水可导致有效应力上升，加剧基坑外沉降．在基坑施工期间，可使用回灌作为有效的沉降控制措施来保护基坑周围的重要建筑物．工程实践表明，在长时间减压抽水后回灌，仅能保证沉降不再发展，很难使沉降完全恢复．针对此问题，采用三维流固耦合有限元模型，对比分析减压井和回灌井在先灌后抽、同灌同抽、先抽后灌\r3\r种方案下土体应力应变特征．研究表明，回灌井与减压井开启顺序对地表沉降影响显著，先抽后灌造成地表沉降最大，沉降值与回灌前抽水时间呈正相关．造成沉降差异的主要原因是上覆弱透水层在不同方案下应力路径不同，从而导致塑性压缩变形不同．在先抽后灌方案中，上覆弱透水层有效应力先升后降，受前期固结压力与回弹模量影响，上覆弱透水层可产生较高的压缩变形．因此，在实际工程中应尽量保证同抽同灌．同时，当抽水量恒定时，相邻弱透水层渗透系数也会改变土体竖向变形分布，下卧弱透水层渗透性越强，地表沉降越小，而上覆弱透水层的渗透性对地表沉降影响较小．\r\r
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Abstract_English:\r\rFor excavation engineering in Tianjin, Shanghai and other coastal areas, owing to the high head of aquifers and their wide distribution, when the safety coefficient of an excavation’s anti-uprush is lacking, confined aquifers need dewatering and relief from pore pressure. Based on the principle of effective stress, decreasing pore pressure can lead to increased effective stress, which could, in turn, increase surface subsidence. If settlement around an excavation is strictly controlled, an artificial recharge will be a utility method. After an extended period of continuous pumping, artificial recharge can only arrest the current level of settlement. Aiming at this problem, using a three-dimensional fluid-solid coupling numerical model, a comparative analysis was conducted of the different features of stress-strain under three conditions: recharge before pressure relief, simultaneous pressure relief and recharge, and pressure relief before recharge. The results of this study showed that the sequencing of opening a recharge well and a pressure relief well has a significant impact on ground settlement. Pressure relief before recharge was found to cause the most ground settlement. Meanwhile, ground settlement increased with the time of pressure relief before recharge wells opened. Through calculation, the main reason for the difference in the ground settlement was the overlying aquitard causing different compressive deformations in different stress paths. For example, under pressure relief before recharge, due to preloading and rebound moduli, effective stress of the overlying aquitard first increased, then gradually decreased, and the overlying aquitard caused more compressive deformation than under the other condition. With a specific quantity of recharge rate and pressure-relief rate, the overlying and underlying aquitard’s conductivity can change the stress-strain of soil. Ground settlement decreases an increase in the underlying aquitard’s conductivity. However, the overlying aquitard’s conductivity will have less effect on ground settlement.\r\r
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Keyword_Chinese:回灌；沉降控制；有限元分析；土体变形\r

Keywords_English:artificial recharge；settlement control；finite element analysis；soil deformation\r


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