土工基础

›› 2019, Vol. 33 ›› Issue (4): 492-494.

• 工程实录 • 上一篇    下一篇

黏性土深基坑侧向卸荷变形特征研究

陶阳平，侯德军   

  1. （深圳市工勘岩土集团有限公司，广东深圳 518054）
  • 收稿日期:2019-06-18 修回日期:2019-06-26 出版日期:2019-08-20 发布日期:2019-08-16
  • 作者简介:陶阳平（1983-），女，工程师，研究方向为基坑支护设计和监测。

Lateral Unloading Deformation Characteristics of Deep Excavation in Cohesive Soils

TAO Yangping,  HOU Dejun   

  1. (Shenzhen Geokey Group Co. Ltd., Shenzhen 518054)
  • Received:2019-06-18 Revised:2019-06-26 Online:2019-08-20 Published:2019-08-16

摘要： 由于基坑侧向卸荷状态下的破坏特征和加载有很大的不同，其产生的安全问题一直是设计施工重中之重。依托于深圳某深基坑工程，开展了一系列K0状态下原状土的固结不排水三轴试验，对基坑开挖过程中，侧向土体的变形特征进行了分析。结果表明：卸荷应力路径下的原状土表现为轴向压缩，但其破坏应变最大仅为2.6%，远远小于常规三轴试验，且不同土样的临界卸荷比相差不大，利用正态分布分析得到所有黏性土的临界卸荷比分布区间为0.14～0.27。分析其本构关系时，发现若使用固结平均压力作为归一化因子，该地区土体具有良好的归一化特征，为该区域卸荷土体的变形及本构关系研究提供参考。

关键词: 深基坑, 黏土, 粉质黏土, 临界卸荷比

Abstract: Under lateral unloading conditions, the failure mode of deep excavations is significant different from that of under loading conditions. In the deep excavation supporting design and foundation construction, the paramount important issue is the safety. A series of undrained triaxial shear tests on undisturbed soil samples under K0 conditions were performed to evaluate the lateral deformation properties of cohesive soils. The test results indicate that, under the unloading stress path, the undisturbed soil samples were under axial compression at the failure state with a maximum axial strain of 2.6%, which is much less that at of in the conventional triaxial shear test on the same soil type. The critical unloading ratios of different soil types are similar, and the ratios demonstrate the normal distribution between 0.14 and 0.27. It is also found that the soil sample demonstrates a good relationship with the average consolidation pressures.

Key words: Deep excavations, cohesive soils, silty clay, critical unloading ratio