考虑地连墙槽段接缝影响的竖井应力和变形规律研究

Stress and Deformation Patterns of Vertical Shafts Considering the Effect of Grooved Section Joints of Diaphragm Walls

由地下连续墙(简称“地连墙”)筑成的圆形围护结构径向变形小,在竖井工程中得到广泛应用,但在计算中如何合理考虑其环向效应是亟待解决的科学问题。为揭示地连墙槽段接缝泥皮对圆形超深竖井应力变形的影响,在某输水隧洞超深竖井数值分析中,采用实体单元模拟地连墙Ⅰ、Ⅱ槽段接缝泥皮,并在地连墙-岩土、混凝土衬砌-地连墙、地连墙-缝间填充物之间均设置接触面,对泥皮缝宽、材料特性进行了参数敏感性研究,获得了竖井支护结构的受力特征。结果表明:地连墙受力以竖向应力与竖向弯矩为主,随缝宽的减小或者缝模量的提高,地连墙的径向位移、竖向弯矩与竖向压力均减小,而环向压力增大;在开挖至土岩交界面时地连墙径向位移与竖向弯矩最大,开挖至坑底时环向弯矩最大。圆形衬砌受力以环向为主,其与地连墙受力方向互补,弥补了地连墙槽段接缝泥皮的环向削弱作用。研究成果可为竖井的设计优化与施工提供技术支撑。

Circular enclosure structures made of diaphragm walls are widely used in shaft construction due to their low radial deformation.However,it remains an urgent scientific problem to reasonably consider its loop effects in calculations.This study aims to reveal the influence of the joint skin of the groove section of the diaphragm wall on the stress and deformation of circular ultra-deep shaft.A solid unit was employed to simulate the joint skin of Ⅰ and Ⅱ groove sections of the diaphragm wall in the numerical analysis of an ultra-deep shaft in a water conveyance tunnel.Moreover,contact surfaces were established between diaphragm wall and rock and soil,concrete lining and diaphragm wall,and also between diaphragm wall and interseam fll.A parametric sensitivity study was conducted to investigate the width of mudskin seams and material properties.Numerical modeling results show that the stress and bending moment of the diaphragm wall are mainly in vertical direction.As excavation progresses to the soil-rock inter-face,the diaphragm wall experiences the largest radial displacement and vertical bending moment.At the pit bottom,the circumferential bending moment reaches peak value.The load direction of circular lining in the top-down method is in the circumferential direction,which is complementary to the stress direction of the diaphragm wall,compensating for the circumferential weakening effect caused by the joint mud skin in the trench section of the diaphragm wall.The research results provide technical support for optimizing the design and construction of ultra deep shafts.