软岩隧道大变形预测模型及支护措施

Large Deformation Prediction Model and Supporting Measures of Soft Rock Tunnel

针对软岩隧道拱顶、拱肩、拱腰等部位的大变形,基于灰色理论对其进行预测,结合锚杆支护,在最大预测值(S_(max))处设计支护,并通过数值模拟分析不同锚杆、间距(d)、长度(L)对围岩最大位移(ν_(max))、最大应力(σ_(max))的控制效果。研究发现:灰色模型预测精度较高,预测最佳时长为一周,最大误差仅为3.01%;随着间距的缩小,树脂锚杆支护较砂浆锚杆支护而言,ν_(max)、σ_(max)分别降低70.69%、58.81%,支护效果显著;随着长度的增加,对围岩变形的约束效果,树脂锚杆较砂浆锚杆更明显,ν_(max)、σ_(max)分别降低57.89%、40.23%;当4.0 m<L<6.0 m,0.5 m<d<1.0 m时,宜采用树脂锚杆支护,其他范围砂浆锚杆支护或树脂锚杆支护控制围岩变形的显著性差异较小。

In view of the large deformation of the vault,arch shoulder,arch waist and other parts of the soft rock tunnel,predicttion was conducted based on the grey theory.Combined with bolt support,the support was designed at the position with the maximum predicted value(S_(max)).And numerical simulation was carried out to analyze the control effects of different bolts,spacing(d)and length(L)on the maximum displacement(ν_(max))and the maximum stress(σ_(max))of surrounding rocks.Researchs indicate that,the grey model has a high prediction accuracy,the best prediction duration is one week,and the maximum error is only 3.01%.With the decrease of spacing,resin bolt support has a better supporting effect compared with mortar bolt support,andνmax andσmaxare reduced by 70.69%and 58.81%respectively.As length of the bolt increases,compared with the mortar bolt support,the resin bolt support has a more obvious restraining effect on the surrounding rock deformation,andνmax andσmax are reduced by 57.89%and 40.23%respectively.When 4.5 m<L<6.0 m and 0.6 m<d<0.7 m,resin bolt support should be adopted,in other conditions,mortar bolt support or resin bolt support has less significant difference in controlling surrounding rock deformation.