富水砂层深基坑支护结构模拟分析与优化

SIMULATION ANALYSIS AND OPTIMIZATION OF DEEP FOUNDATION PIT SUPPORTING STRUCTURE IN WATER-RICH SAND LAYER

基于北京市通州区某深基坑工程,依据降水开挖及支护方案,使用midas GTS NX软件建模研究了在土钉墙-桩锚联合支护下,不同锚杆条件对富水砂层深基坑开挖变形特征的影响,并基于实际施工方案进行支护结构优化。结果表明,桩锚支护中预应力锚杆能够有效加固深层土体,约束其水平位移,显著改善基坑稳定性,相较于无锚杆情况,坡顶和桩顶的水平位移最大值分别减少了60.9%和75.4%;桩锚支护情况下,桩身侧移随桩直径的增大先减小后增大,存在最优桩直径范围,且该范围受到锚杆预应力大小的影响。

Based on a deep foundation pit project in Tongzhou,Beijing,according to the dewatering excavation and supporting scheme,midas GTS NX software was used to model and study the influence of different anchor conditions on the excavation deformation characteristics of deep foundation pit in water-rich sand layer under the combined support of soil nailing wall and pile-anchor,and the supporting structure was optimized based on the actual construction scheme.The results show that the prestressed anchor bolt in pile-anchor support can effectively strengthen the deep soil,restrain its horizontal displacement and significantly improve the stability of foundation pit.Compared with the condition without anchor bolt,the maximum horizontal displacement of slope top and pile top are reduced by 60.9% and 75.4% respectively.In the case of pile-anchor support,with the increase of pile diameter,the lateral displacement of pile decreases first and then increases,and there is an optimal pile diameter range,which is affected by the prestress of anchor bolt.