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从现场勘查、室内试验和数值计算的角度对某厂房出露的B类角砾岩的岩体特性、力学性质与开挖卸荷后围岩稳定性做系统的分析。室内试验结果表明,0~15 MPa围压下B类角砾岩表现典型的弹脆塑性;饱水试样在相对较高围压下加载时,试样的变形趋于均匀化,此时弹性模量不再随围压增大而增大。峰值强度的离散性较大,这是由于试样中方解石含量不同,随方解石含量增大,试样峰值强度增大;饱水状态试样较天然状态内摩擦角小而黏聚力大,体现水对角砾岩黏结强度的提高和内摩擦因数的弱化作用;利用角砾岩区域的三维数值模型计算得到开挖卸荷条件下B类角砾岩区域围岩的基本力学响应。计算结果与现场监测数据吻合较好。经过对B类角砾岩出露区域系统地加强支护,确保了施工期角砾岩区域的稳定性。
Based on field investigation, laboratory test and numerical calculation, the rock mass characteristics and mechanical properties of Class B breccia exposed from a factory are systematically analyzed. The results of laboratory tests show that the type B breccia under 0 ~ 15 MPa confining pressure shows typical brittleness and plasticity. When the saturated sample is loaded at a relatively high confining pressure, the deformation of the sample tends to be uniform. At this time, the elasticity Modulus no longer increases with increasing confining pressure. The dispersion of the peak intensity is larger, which is due to the different calcite content in the sample. With the increase of calcite content, the peak intensity of the sample increases. Compared with the natural state, the saturated friction coefficient is small and the cohesion is large And the weakened effect of the internal friction factor. The basic mechanical response of surrounding rock in the B class breccia area under the condition of excavation and unloading is calculated by using the three-dimensional numerical model of breccia area. The calculated results are in good agreement with the on-site monitoring data. After the type B breccia exposed areas to strengthen the support system to ensure the stability of the breccia area during construction.