西安饱和软黄土隧道变形控制及其适用性
康佐魏琪
Deformation Control and Applicability of Xi’an Saturated Soft Loess Tunnel
KANG ZuoWEI Qi
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作者信息:西安市轨道交通集团有限公司， 710018， 西安
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Affiliation:Xi’an Rail Transit Group Co., Ltd., 710018, Xi’an, China
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关键词:
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Key words:
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DOI:10.16037/j.1007-869x.2023.09.007
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中图分类号/CLCN:U455.4
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栏目/Col:研究报告
摘要:
西安地区有大量的饱和软黄土，其具有承载力差、压缩性强和工程性质较差等特点，因此需针对饱和软黄土特殊的物理力学性质，研究西安饱和软黄土隧道变形控制及其适用性。方法：以西安地铁4号线穿越饱和软黄土工程为例，对比分析了止水与降水措施对隧道施工结构及土层变形的控制效果。结果及结论：研究结果表明：① 在饱和软黄土的影响下，隧道变形以竖向变形为主，拱顶处的最大沉降值为63 mm，拱底处的最大隆起量为68 mm，最大水平位移为18 mm。② 当采用台阶法施工时，地面中心点沉降值最大；当采用CRD(中隔墙加台阶)法施工时，地面中心点沉降值次之；当采用盾构法施工时，地面中心点沉降值最小,盾构施工对地层的扰动相对较小。③ 降水和止水措施均可有效降低土层含水率；当采用降水措施时，地面和建筑物的沉降总量较大，但两者间的差异沉降较小，沉降曲线呈台阶式分布；当采用止水措施时，地面和建筑物的沉降总量较小，整体呈平缓递增的趋势。现场监测结果表明：① WSS(无收缩双液)注浆后，开挖轮廓外2 m范围内的土体强度达到了12 MPa，开挖范围内的土体强度达到了06 MPa；② 与降水措施相比，WSS注浆后的地面沉降量减少了65%，拱顶处的沉降量减少了50%；③ 数值模拟结果与现场监测数据相吻合，验证了数值模拟的准确性。
Abstracts:
In Xi’an, there is a large amount of saturated soft loess, exhibiting characteristics such as poor bearing capacity, strong compressibility, and unfavorable engineering properties. Therefore, it is necessary to study the deformation control and applicability of Xi’an saturated soft loess tunnel construction, considering its unique physical and mechanical properties.Method: Taking the construction of Xi′an Metro Line 4 through saturated soft loess engineering as example, the control effects of water stoppage and dewatering measures on tunnel construction structure and soil deformation are mainly compared and analyzed.Result & Conclusion: The research results show that: (1) Under the influence of saturated soft loess, vertical deformation dominates in tunnel deformation. The maximum settlement at arch crown is 6.3 mm, the maximum heave at arch bottom is 6.8 mm, and the maximum horizontal displacement is 1.8 mm. (2) When using the stepped excavation method, the maximum land subsidence occurs at ground center. When using the CRD (center cross diaphragm) construction with stepped method, the land subsidence at ground center is second to the maximum. When using shield method, the land subsidence at ground center is the least, indicating relatively less disturbance to stratum. (3) Both dewatering and water stoppage measures can effectively reduce the soil moisture content. When dewatering measures are used, the total subsidence and settlement of land and building is significant, but the difference in settlement between them is small, resulting in a stepped distribution of settlement curve. When water stoppage measures are used, the total subsidence and settlement of land and building is small, showing a trend of gradual increase. Fieldmonitored results show that: (1) After WSS (double slurry grouting) injection, the soil strength within 2 m outside the excavation contour reaches 1.2 MPa, and the soil strength within the excavation range reaches 0.6 Mpa. (2) Compared to dewatering measures, the land subsidence amount is reduced by 65% and the settlement at arch crown is reduced by 50% after WSS grouting. (3) Numerical simulation results agree with the fieldmonitored data, confirming the accuracy of the numerical simulation.
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