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承压水作用下,内撑式深基坑的突涌稳定状态与围护墙水平位移、土压力分布及坑底回弹变形等因素密切相关。建立了深基坑突涌稳定的数值分析模型,分析不同承压水位作用下的坑底突涌破坏机制、稳定性及相应的基坑变形性状,并与已有分析方法作对比。分析结果表明,承压水作用下,基坑围护墙内侧隔水层表面剪切应变最大,是突涌破坏的最危险位置。随着坑底承压水位的升高,隔水层内的剪切应变增量逐渐变大并向下部土层发展,最终在隔水层与承压含水层界面处产生楔裂破坏,隔水层整体顶升破坏。同时,基坑变形状态表现为,围护墙弯矩和水平位移逐渐增大,被动侧土压力逐渐减小,最终围护墙发生踢脚破坏,坑底土体大量隆起回弹。相对于压力平衡法和均质连续梁板法等理论方法,数值分析方法可以分析坑底土体的突涌渐进发展过程,较好地反应内撑式基坑抗突涌稳定性与围护墙及土体变形性状的相互影响,计算结果更为符合工程实际。
Under the action of confined water, the inrush stability of the deep foundation pit with internal support is closely related to the horizontal displacement of the retaining wall, the distribution of earth pressure and the rebound deformation of the bottom. The numerical analysis model for the inrushing and inrush of deep foundation pit is established. The mechanism and stability of the underburst surge under pitfall and the corresponding deformation characteristics of the foundation pit under different pressure water levels are analyzed and compared with the existing analysis methods. The results show that under the action of confined water, the maximum shear strain of the aqueduct inside the retaining wall of the foundation pit is the most dangerous position for sudden surge damage. As the pressure level at the bottom of the pit increases, the shear strain increment in the aquitard gradually becomes larger and develops toward the lower soil layer, eventually resulting in wedge cracking at the interface between the aquitard and the confined aquifer, The overall rise and destruction of the layer. At the same time, the deformation state of the foundation pit shows that the bending moment and horizontal displacement of the retaining wall gradually increase, and the earth pressure on the passive side gradually decreases. Finally, the kick wall of the retaining wall breaks down and a large amount of spring soil rebounds. Compared with the pressure equilibrium method and the homogeneous continuous beam method, the numerical analysis method can analyze the gradual development of the inrush of the soil at the bottom of the pit and better reflect the surge inburst stability of retaining foundation pit and the wall and soil The mutual influence of the deformation of the body, the calculation results more in line with the actual project.