外基坑宽度对坑中坑条件下被动土压力的影响  

Influence of external pit width on passive earth pressure under pit-in-pit condition

作　　者：潘静杰 朱春柏 刘伟 房凯[4] 刘念武[1] Pan Jingjie;Zhu Chunbai;Liu Wei;Fang Kai;Liu Nianwu(School of Civil Engineering and Architecture,Zhejiang Sci-Tech University,Hangzhou 310000;Crrc Construction Engrg,Co.Ltd.,Beijing 100078,China;Suzhou Crrc Construction Engrg,Co.Ltd.,Suzhou Jiangsu 215008,China;College of Energy and Mining Engineering,Shandong University of Science and Technology,Qingdao Shandong 266000,China)

机构地区：[1]浙江理工大学建筑工程学院,杭州310000 [2]中车建设工程有限公司,北京100078 [3]苏州中车建设工程有限公司,江苏苏州215008 [4]山东科技大学能源与矿业工程学院,山东青岛266000

出　　处：《地质科技通报》2023年第1期62-69,共8页Bulletin of Geological Science and Technology

基　　金：国家自然科学基金项目(52078466)。

摘　　要：工程实践表明,外基坑宽度和坑中坑会影响基坑坑底滑裂面的形成方式,因此,经典朗肯土压力理论的假设建立在半无限空间土体的基础上不再适用。基于极限平衡理论和微分体受力平衡方法,考虑土体黏聚力和围护结构与滑动土体摩阻力,推导了宽基坑和窄基坑坑中坑的被动土压力理论计算公式。通过具体算例对比了宽基坑与窄基坑在坑中坑条件下被动土压力大小的变化趋势。结果表明,考虑摩擦力条件下的被动土压力大于未考虑摩擦力的被动土压力;无论宽基坑还是窄基坑,有内坑的被动土压力小于无内坑时的被动土压力;无内坑时,外基坑宽度的增加导致被动土压力减小,而在有内坑的情况下,外基坑宽度的增加,反而增大被动土压力;在窄基坑中,随着内坑位置的移动,土压力先变小后增大,且内坑平面尺寸的增大导致土压力逐渐减小。因此,内坑的存在将降低坑中坑基坑的外坑被动土压力,工程中应注意内坑的存在。Engineering practice shows that the width of the external foundation pit and the pit in the pit will have a influence on the ways of formation process of the slip surface at the bottom of the foundation pit.Thus, Rankine earth pressure theory based on conventional semi-infinite space is not applicable for calculating the earth pressure acting on the retaining structure for pit-in-pit excavations.Based on the limit equilibrium theory and the fractional force equilibrium method, the theoretical formulas for calculating the passive earth pressure of wide pit and narrow pit are derived, considering the cohesive force of soil and the friction resistance between the retaining structure and sliding soil.For example, the variation trends of passive earth pressure of wide pit and narrow pit in pit condition are compared.The results show that the passive earth pressure considering friction is larger than the passive earth pressure without friction.For both wide and narrow foundation pits, the passive earth pressure with the inner pit is less than that without the inner pit.When there is no inner pit, the increase of the width of the outer foundation pit leads to the decrease of the passive earth pressure, while when there is an inner pit, the increase of the width of the outer foundation pit increases the passive earth pressure.In the narrow foundation pit, the earth pressure decreases first and then increases with the movement of the pit position, and the increase of the pit in the pitplane dimension leads to the gradual decrease of the earth pressure.Thus, the existence of the inner pit will greatly reduce the passive pressure of outer one, and attention should be paid to the existence of inner pits in engineering.

关 键 词：基坑宽度 坑中坑 有限土体 被动土压力 滑裂面 

分 类 号：P642.11[天文地球—工程地质学]