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摘要: 为有效加固铁路软弱基床, 保证列车安全运营, 运用Marc软件对土工格室加固基床的工程性状开展了有限元分析, 分别选择34cm×10cm、40cm×10cm、34cm×15cm和40cm×15cm(焊距×高度)4种规格的土工格室, 应用平板载荷试验方法进行了土工格室加固的软弱基床承载力足尺模型试验, 同时采用土工格室加固方法, 对阳安铁路K241+450~550段的软弱基床进行了处治。结果表明土工格室可有效约束软弱基床的侧向位移和扩散应力, 最大侧向位移可减少17%, 最大竖向应力减少9.3%, 且使应力分布更加均匀; 加固后的基床承载力达180kPa以上, 降低加固费用6%~12%;加固地段6a累计最大沉降为28mm, 最小沉降为13mm, 达到了加固铁路软弱基床的目的。Abstract: In order to reinforce the soft subgrade of railway effectually, guarantee train safety, the engineering mechanism of railway subgrade reinforced by geocell was analyzed by using Marc program, a full-scale load-bearing test of soft subgrade reinforced by 4 types of geocells was carried out, by using flat load-test method. The different types of geocells are 34 cm×10 cm, (40 cm)×10 cm, 34 cm×15 cm and 40 cm×15 cm. The subgrade disease in the site of K241+(450~)550 of Yang'an railway was treated by using geocell. The result shows that geocell can restrict the lateral replacement and diffuse stress of railway subgrade effectively, its maximum lateral replacement is decreased by 17%, its maximum vertical stress is decreased by 9.3%, its stress is well-distributed by using geocell, its bearing capacity can reach more than 180 kPa, the cost of reinforced subgrade by using geocell is decreased by 9.3%. On-the-spot observation in 6 a shows that its maximum settlement is 28 mm, its minimum settlement is 13 mm. This engineering practice proved that the method of using geocell to reinforcing railway subgrade is effective.
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表 1 土工格室材料性能指标
Table 1. Geocell indices
环境应力开裂时间/h 低温脆化温度/℃ 高温软化温度/℃ 拉伸屈服强度/MPa 拉伸模量/MPa 焊缝处抗拉强度/(N·cm-1) 边缘联接处抗拉强度/(N·cm-1) 中间联接处抗拉强度/(N·cm-1) 1000 -60 124 24 650 106 260 162 表 2 计算参数
Table 2. Computational parameters
容重/(kN·m-3) 粘聚力/kPa 摩擦角/(°) 弹性模量/MPa 砂砾层 20.0 0 45 72.0 土工格室层 19.0 190 45 90.0 软基层 17.5 15 20 2.0 正常土层 19.0 40 40 30.0 表 3 模型试验用砂砾筛分结果
Table 3. Screening sand-gravel result of model test
编号 筛孔(mm)通过量/% 40.0 30.0 20.0 10.0 5.0 2.5 1.2 0.6 1 96.2 77.3 27.9 12.7 7.4 6.6 6.2 1.4 2 97.2 80.4 20.6 8.9 6.8 6.4 6.2 1.8 平均 96.7 78.8 24.2 10.8 7.1 6.5 6.2 1.6 表 4 试验用砂筛分结果
Table 4. Screening sand result of test
编号 筛孔(mm)通过量/% 0.600 0.300 0.150 0.074 1 93.2 52.1 19.7 2.1 2 91.3 49.6 17.3 1.7 平均 92.2 50.8 18.5 1.9 表 5 现场观测数据
Table 5. Observation settlement data /mm
测点位置 观测时间 1997-1-26 1997-5-8 1997-10-18 1998-5-10 1998-10-20 1999-5-6 1999-10-25 2000-5-10 2000-10-24 2001-5-15 2001-10-21 2002-5-12 2002-10-28 K241+455 右轨下 8.766 8.760 8.752 8.751 8.747 8.746 8.744 8.744 8.742 8.742 8.742 8.742 8.742 左轨下 8.765 8.761 8.753 8.751 8.748 8.748 8.745 8.744 8.744 8.744 8.740 8.740 8.740 道心 8.765 8.762 8.755 8.754 8.750 8.749 8.748 8.748 8.748 8.748 8.748 8.748 8.748 右路肩 8.763 8.761 8.757 8.756 8.754 8.754 8.753 8.753 8.752 8.752 8.750 8.750 8.750 左路肩 8.763 8.762 8.756 8.756 8.755 8.755 8.752 8.752 8.748 8.748 8.748 8.748 8.748 K241+475 右轨下 8.768 8.762 8.758 8.754 8.749 8.748 8.745 8.745 8.741 8.741 8.741 8.741 8.741 左轨下 8.769 8.764 8.758 8.755 8.751 8.751 8.747 8.747 8.744 8.744 8.742 8.742 8.742 道心 8.767 8.763 8.759 8.757 8.753 8.752 8.750 8.749 8.749 8.749 8.749 8.749 8.749 右路肩 8.765 8.762 8.757 8.755 8.753 8.753 8.752 8.752 8.752 8.751 8.751 8.751 8.751 左路肩 8.765 8.761 8.756 8.755 8.755 8.755 8.753 8.752 8.750 8.750 8.750 8.750 8.750 K241+495 右轨下 8.766 8.761 8.753 8.752 8.751 8.747 8.743 8.743 8.740 8.740 8.738 8.738 8.738 左轨下 8.768 8.762 8.755 8.753 8.751 8.748 8.742 8.742 8.740 8.740 8.740 8.740 8.740 道心 8.768 8.763 8.760 8.757 8.753 8.750 8.747 8.747 8.747 8.747 8.747 8.747 8.747 右路肩 8.764 8.761 8.757 8.755 8.752 8.752 8.750 8.750 8.748 8.758 8.748 8.748 8.748 左路肩 8.764 8.762 8.755 8.753 8.753 8.752 8.751 8.750 8.750 8.750 8.750 8.750 8.750 注: 表中高程为相对高程, 基点设为10.000 m。 -
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