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Interaction between Overpass Bridge Foundation and Deep Foundation Pit in Adjacent Construction
DOI: 10.12677/HJCE.2022.117095, PDF, HTML, XML, 下载: 98  浏览: 138

Abstract: In order to reduce the interaction between overpass foundation and deep foundation pit in adjacent construction, a common solution is to reinforce the surrounding soil of bridge foundation in practicle projects. This paper carried out a numerical simulation method with Midas GTS NX by adapting the soil around the pile foundation with different soil properties and different reinforcement ranges, so as to find out the influence pattern of reinforcement parameters in interaction between bridge foundation and foundation pit. The results show that, before increasing the soil property parameters of the reinforced soil by 1 time, for every 50% increase of the soil property parameters, the surface settlement of the foundation pit will be reduced by about 5%; after the critical value is exceeded, the control effect of the foundation pit deformation is not significantly improved by continuing to increase the soil property parameters. When the reinforcement range is expanded to 14 m laterally from the bridge abutment, and within 12 m longitudinally from the bridge abutment, expanding the reinforcement range can effectively reduce the surface settlement of the foundation pit. After this range is exceeded, the reinforcement effect is almost unchanged; the lateral deformation of the underground diaphragm wall will increase slightly, but it is not obvious; the longitudinal settlement of the bridge foundation shows a trend of small on both sides and large in the middle. Improving the reinforcement parameters of the soil can reduce the settlement of the bridge foundation to a certain extent.

1. 引言

2. 工程概况

Table 1. Soil layer parameters

3. 计算模型与计算工况

3.1. 计算模型

Figure 1. Cross-section of bridge foundation and foundation pit

Figure 2. Numerical calculation model

3.2. 工况模拟

4. 土体加固参数影响分析

4.1. 土性加固的影响

1) 基坑地表沉降

Figure 3. Pit deformation of soil around bridge foundation with different reinforcement parameters

Figure 4. Surface settlement of foundation pit before and after reinforcement of soil around bridge foundation

2) 地连墙侧向变形

Figure 5. Lateral displacement of diaphragm wall before and after reinforcing soil around bridge foundation

3) 高架桥桥基沉降

Figure 6. Displacement of bridge foundation before and after reinforcement of bridge foundation

Figure 7. Foundation pit surface displacement of II-II’ section

4.2. 加固范围的影响

Figure 8. Reinforcement area partition diagram

Figure 9. Foundation pit settlement with different reinforcement areas

Figure 10. Settlement of foundation pit in mid-span cross-section with different reinforcement areas

2) 地下连续墙

Figure 11. Lateral displacement of diaphragm wall with different reinforcement areas

3) 高架桥桥基沉降变形

5. 结论

Figure 12. Pile foundation settlement with different reinforcement areas

Figure 13. Surface settlement in II-II’ section with different reinforcement areas

1) 对桥基周围土体进行加固，以提高土体的工程性质，可减小基坑地表沉降和桥基沉降。在提高加固体压缩模量1倍以前，每提高压缩模量50%，基坑地表最大沉降约减小5%，但在提高1倍以后，提高压缩模量产生的加固效果逐渐减弱。

2) 基坑地表沉降还与桥基四周加固范围有关，在加固范围扩大至横向距离桥台14 m，纵向距离桥台12 m以内时，加固效果与加固范围成正比。但超过该范围后，扩大加固范围并不能提高加固效果。因此需要根据工程容许沉降，选择加固范围2以内，既可以减少施工的相互影响，又可以降低工程施工投资。

3) 数值分析结果发现桥基施工并不会引起明显地连墙侧移，并且土体加固的挤压作用还会使地连墙侧移有所增加，但增加并不明显，不会影响地下连续墙的槽壁稳定性。

4) 基坑开挖后，桥基纵向的地表沉降呈现出两边小，中间大的盆形曲线。加固范围小于加固范围2时，扩大加固范围可以有效减小桥基沉降；一旦超过该范围后，继续扩大加固范围对减小桥基沉降并无太大作用，因此应该对桥基中心处着重加固和监测。

NOTES

*通讯作者。

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